1.6.2 Saran - Laboratorium Pengujian Bahan

Kelompok xx
Latar Belakang Pengujian
BAB I
LATAR BELAKANG PENGUJIAN
Seperti kita ketahui bahwa dalam bidang industri permesinan tidak terlepas dari
ilmu logam terutama menyangkut masalah – masalah yang ada hubungannya dengan
pemilihan kualitas bahan, cara – cara pengerjaannya, dan untuk penekanan biaya
produksi.
Percobaan yang dilakukan di Laboratorium Pengujian Bahan Fakultas Teknik
Universitas Brawijaya, merupakan salah satu inspeksi untuk mengetahui kualitas logam,
hal ini perlu sekali karena berkaitan dengan produk yang akan dihasilkan. Sebelum
memproduksi suatu bahan kita harus mengetahui spesifikasi bahan tersebut. Dengan
demikian kita akan mengetahui langkah apa yang perlu diambil dalam proses
pengerjaan dan sekaligus dapat kita ketahui bahan yang kita gunakan memenuhi syarat
untuk produk yang telah ditargetkan baik mutu maupun dimensinya.
Dengan mengetahui spesifikasi bahan, langkah – langkah proses pengerjaan dan
mutu yang ditargetkan akan mencapai hasil yang tepat. Dari sini biaya produksi dapat
dipilih, tentunya digunakan biaya yang paling murah. Jadi, apabila kita ingin
memproduksi suatu bahan yang berkualitas baik, maka kita harus mengetahui
spesifikasi bahan yang digunakan. Spesifikasi suatu bahan dapat diketahui dengan
melakukan pengujian – pengujian yang kita lakukan di laboratorium. Oleh karena itu
dilakukan pengujian untuk mengetahui sifat mekanik suatu material di Laboratorium
Pengujian Bahan Fakultas Teknik Universitas Brawijaya.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
1
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
BAB II
PENGUJIAN KEKERASAN DAN MIKROSTRUKTUR
2.1 Tujuan Pengujian
1.
Mengetahui angka kekerasan suatu bahan.
2.
Mengetahui pengaruh perlakuan panas terhadap kekerasan bahan.
3.
Mengetahui salah satu cara pengukuran kekerasan.
4.
Mengetahui perubahan struktur pada setiap perlakuan.
2.2 Definisi Kekerasan
........................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
2.3 Pelaksanaan Pengujian
2.3.1 Alat dan Bahan yang Digunakan
Untuk Uji Kekerasan
1.
Rockwell Type Hardness Tester
Digunakan untuk mengukur kekerasan pada spesimen.

Merk
: CV 600A

Indentor bola Rockwell
: 1/16"

Indentor intan
: 120

Buatan
: Jerman

Skala pembebanan
: HRA = 588 N
HRB = 980 N
HRC = 1471 N
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
2
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Gambar 2.1 Rockwell Type Hardness Test
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
2.
Centrifugal Sand Paper Machine
Digunakan untuk menghaluskan benda kerja.

Merk
: SAPHIR 330

Buatan
: Jerman

Diameter
: 15 cm

Putaran
: 120 rpm

Daya
: 0.55 kW

Tegangan
: 220
Gambar 2.2 Centrifugal Sand Paper Machine
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
3.
Dapur Listrik
Dapur ini digunakan untuk proses pemanasan (heating), penahanan
(holding), dan pendinginan (cooling) dalam dapur.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
3
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Spesifikasi dapur listrik yang digunakan adalah :

Merk
: OPENBAU HOFMANN

Tipe
: E / 90

Voltage
: 220 volt

Daya
: 3,3 kW

Suhu max
: 1100oC

Buatan
: Austria
Gambar 2.3 Dapur Listrik
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
4.
Tang penjepit
Digunakan untuk mengambil benda uji dari dapur listrik pada proses
perlakuan panas.
Gambar 2.4 Tang Penjepit
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
5.
Bak pendingin
Digunakan sebagai tempat media pendingin spesimen pada perlakuan panas
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
4
Kelompok xx
6.
Pengujian Kekerasan dan Mikrostruktur
Stopwatch
Digunakan untuk mengukur waktu holding
Gambar 2.6 Stopwatch
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
7.
Kertas Gosok
Digunakan untuk membersihkan spesimen dari terak dan kotoran.
Gambar 2.7 Kertas Gosok
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
8.
Jangka Sorong
Digunakan untuk mengukur dimensi spesimen
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
5
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Gambar 2.8 Jangka Sorong
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
9.
Penggaris
Digunakan untuk mengukur dimensi spesimen
Gambar 2.9 Penggaris
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
Untuk Mikrostruktur
1.
Mikroskop Logam
Digunakan untuk melihat mikrostruktur specimen, Dalam pengujian ini
digunakan pembesaran 450 kali.
Spesifikasi mikroskop logam yang digunakan :

Merk
: Nikon

Buatan
: Jepang
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
6
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Gambar 2.10 Mikroskop Logam
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
2.
Kamera
3.
Etsa
Digunakan untuk memperjelas penampakan struktur mikro spesimen. Etsa
berupa cairan kimia yang akan bereaksi dengan atom tertentu pada logam,
terutama atom – atom yang tidak stabil, misalnya atom pada batas butir. Etsa
yang digunakan pada pengujian ini adalah nital, yang merupakan campuran 1 – 5
ml white nitric acid dalam 100 ml ethyl / methyl alcohol 95 – 100 %. Nital akan
menggelapkan perlit, menampakkan batas butir cementite.
Gambar 2.11 Etsa
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
4.
Metal polish
Digunakan untuk menghaluskan dan mengkilapkan permukaan spesimen.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
7
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Gambar 2.12 Metal Polish
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
9.
Kain flanel
Digunakan untuk menghaluskan dan membersihkan spesimen dari metal
polish yang tersisa.
Gambar 2.13 Kain Flanel
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)

Komposisi Kimia Spesimen
- Spesimen : Bohler Special K
- Komposisi :
:
C =2%
Mn = 0,3 %
Si = 0,2 %
Cr = 12 %
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
8
Kelompok xx

Pengujian Kekerasan dan Mikrostruktur
Pergeseran Titik Eutectoid
Tabel 2.1 Komposisi Kimia
Unsur
Komposisi
No
Paduan
(%)
1
C
2
2
Mn
0.3
3
Si
0.2
4
Cr
12
Suhu Eutectoid
%C
Sumber : Dokumentasi Pribadi (2016)
10x10 cm
Gambar 2.14 Grafik Pegeseran Titik Eutectoid
Sumber : Dokumentasi Pribadi (2016)

Bentuk dan Dimensi Spesimen
(LAMPIRAN)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
9
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
2.3.2 Prosedur Pengujian
Uji Kekerasan
1.
Permukaan benda uji dibersihkan dari kotoran dan terak dengan kertas gosok.
2.
Spesimen dipanaskan dan di-holding dengan suhu dan waktu tertentu.
3.
Spesimen dipindahkan dari dapur listrik ke bak pendingin untuk proses
pendinginan pada media tertentu
4.
Siapkan permukaan benda kerja:
a. Ratakan kedua permukaan benda kerja menggunakan amplas kasar, sehingga
kedua bidang permukaan tersebut sejajar.
b. Haluskan permukaan benda kerja menggunakan centrifugal sand paper
machine sampai betul – betul rata dan halus dan siap diuji.
5.
Siapkan perangkat uji kekerasan Rockwell C pada Universal Hardness Tester:
a. Memasang bandul beban (1471 N).
b. Memasang indentor intan.
c. Memasang benda kerja pada landasan
d. Atur tuas pada posisi Unloading
4. Putar turn wheel searah jarum jam secara perlahan hingga benda kerja
menyentuh indentor tanpa mengalami impact, sampai jarum besar berputar
sebanyak tiga kali pada skala C dan jarum kecil bergerak dari titik hitam
menunju pada titik merah.
5. Dorong tuas pembebanan ke arah loading secara perlahan – lahan. Tunggu hingga
jarum besar pada skala berhenti dengan sendirinya.
6.
Tunggu selama 10 detik dari saat berhentinya jarum, kemudian gerakkan tuas ke
unloading secara perlahan-lahan sampai maksimal. Dengan naiknya tuas, jarum
ikut berputar searah putaran jarum jam sampai akhirnya berhenti.
7.
Baca harga kekerasan HRC pada saat jarum telah berhenti. Bacalah pada skala C
yang berwarna hitam.
8.
Ulangi langkah 5 – 7 sampai didapatkan 10 nilai kekerasan dari spesimen
tersebut.
Uji Mikrostruktur
1.
Permukaan spesimen yang akan difoto diratakan dan haluskan dengan
centrifugal sand paper machine.
2.
Permukaan spesimen dihaluskan dengan metal polish dan digosok dengan kain
flanel samapi benar – benar mengkilap dan halus.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
10
Kelompok xx
3.
Pengujian Kekerasan dan Mikrostruktur
Permukaan spesimen yang sudah mengkilap dibersihkan dengan alkohol,
kemudian ditetesi cairan etsa.
4.
Spesimen diletakkan pada mikroskop logam, kemudian fokus diatur sampai
didapatkan gambar yang jelas dengan pembesaran 450 kali.
5.
Dilakukan pemotretan dengan kamera, kemudian hasilnya dicetak.
2.4 Pengolahan Data
2.4.1 Analisa Mikrostruktur

Mikrostruktur Tanpa Perlakuan Panas
Kertas Foto
10 x 4 cm
Gambar 2.15 Mikrostruktur Material Tanpa Perlakuan
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
Dari hasil foto mikrostruktur tersebut diambil sepuluh sampel untuk
dihitung presentase warna hitam dan putih.
Tabel 2.1 Mikrostruktur Material Tanpa Perlakuan
1
2
3
4
5
6
7
8
9
10
Sumber : Dokumentasi Pribadi (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
11
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Dari sepuluh sampel tersebut dapat diperoleh data sebagai berikut :
Tabel 2.2 Presentase Putih - Hitam
No.
Putih (%)
Hitam (%)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
∑
Sumber : Dokumentasi Pribadi (2016)
Proporsi dari sampel (p1) :
n1 = 10 x 100 = 1000
p1 =
= ……….=………
standar deviasi sampel (δ1)
q1 = 1 - p1 = 1 - …….. = ………
δ1 =
=………..= ………
Dari tabel distribusi standar dengan α = 5% maka diperoleh nilai Z(α/2) = ±………
interval penduga rata-rata proporsi warna putih :
p1 – Z(α/2).δ1 < p < p1 + Z(α/2). δ1
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
12
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Jadi proporsi warna putih untuk foto mikrostruktur logam tanpa perlakuan
panas berkisar antara ………. sampai ………. dengan tingkat keyakinan 95%

Mikrostruktur dengan Perlakuan Panas
Kertas Foto
10 x 4 cm
Gambar 2.16 Mikrostruktur Material dengan Perlakuan ……
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
Dari hasil foto mikrostruktur tersebut diambil sepuluh sampel untuk
dihitung presentase warna hitam dan putih.
Tabel 2.3 Mikrostruktur Material dengan Perlakuan ……
1
2
3
4
5
6
7
8
9
10
Sumber : Dokumentasi Pribadi (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
13
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Dari sepuluh sampel tersebut dapat diperoleh data sebagai berikut :
Tabel 2.2 Presentase Putih - Hitam
No.
Putih (%)
Hitam (%)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
∑
Sumber : Dokumentasi Pribadi (2016)
Proporsi dari sampel (p1) :
n1 = 10 x 100 = 1000
p1 =
= ……….=………
standar deviasi sampel (δ1)
q1 = 1 - p1 = 1 - …….. = ………
δ1 =
=………..= ………
Dari tabel distribusi standar dengan α = 5% maka diperoleh nilai Z(α/2) =
±……….. interval penduga rata-rata proporsi warna putih :
p1 – Z(α/2).δ1 < p < p1 + Z(α/2). δ1
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
14
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Jadi proporsi warna putih untuk foto mikrostruktur logam tanpa perlakuan
panas berkisar antara ………. sampai …….. dengan tingkat keyakinan 95%

Uji Beda Dua Proporsi
Untuk mengetahui perbedaan antara proporsi warna putih spesimen tanpa
perlakuan panas dan spesimen dengan perlakuan panas dilakukan pengujian dua
proporsi
Hipotesa : H0 : p1 = p2
H1 : p1 ≠ p2
Data untuk menghitung Zhitung
n1=1000
p1=………
q1=………
n2=1000
p2=………
q2=………
perhitungan Zhitung :
Zhitung =
=
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
Kedudukan Zhitung pada kurva normal adalah sebagai berikut :
Milimeter Block
5 x 12 cm
Grafik 2.1 Kurva uji Z
Sumber : Dokumentasi Pribadi (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
15
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
...................................................................................................................................
...................................................................................................................................
..................................................................................................................................
...................................................................................................................................
...................................................................................................................................
2.4.2 Data Kelompok

Data Spesimen Tanpa Perlakuan Panas
Tabel 2.5 Data Spesimen Tanpa Perlakuan
No
X
[ X – 𝑋]
[ X – 𝑋]2
1
2
3
4
5
6
7
8
9
10
Σ
Sumber : Dokumentasi Pribadi (2016)
Kekerasan rata-rata
𝑋=
= ……….=……….
Standar deviasi
𝛿=
= ………........=………….
Standar deviasi rata-rata
 

=………........=………….
n
Db = n - 1 = 10 – 1 = 9
Dengan nilai α = 5 % maka nilai t tabel = t(α/2;db) = t (...........; 9) = ...............
Interval penduga kekerasan spesimen tanpa perlakuan panas.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
16
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
Milimeter Block
5 x 12 cm
Grafik 2.2 Uji Tanpa Perlakuan
Sumber : Dokumentasi Pribadi (2016)
Jadi kekerasan rata-rata spesimen tanpa perlakuan panas berkisar antara
……….. sampai ……….. dengan tingkat keyakinan 95%

Data Spesimen dengan perlakuan panas
Tabel 2.6 Data Spesimen dengan Perlakuan ……
No.
X
[ X – 𝑋]
[ X – 𝑋]2
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Σ
Sumber : Dokumentasi Pribadi (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
17
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
Kekerasan rata-rata
𝑋=
= …….=…….
Standar deviasi
𝛿=
= ………........=………….
Standar deviasi rata-rata
 

=………........=………….
n
Db = n-1 = 10 – 1 = 9
Dengan nilai α = 5% maka nilai t tabel = t(α/2;db) = = t ( ......... ; 9) = ..........
Interval penduga kekerasan spesimen tanpa perlakuan panas
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
...................................................................................................................................
Milimeter Block
5 x 12 cm
Grafik 2.2 Uji dengan Perlakuan ……
Sumber : Dokumentasi Pribadi (2016)
Jadi kekerasan rata-rata spesimen tanpa perlakuan panas berkisar antara
…………sampai ………… dengan tingkat keyakinan 95 %
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
18
Kelompok xx

Pengujian Kekerasan dan Mikrostruktur
Uji Beda Dua Rata – Rata
Untuk mengetahui ada tidaknya perbedaan kekerasan pada spesimen
tanpa perlakuan dan dengan perlakuan panas dilakukan uji beda dua rata- rata
dengan uji standart.
Hipotesa : Ho : μ1 =μ2
H1 : μ1 ≠μ2
Digunakan pengujian dua arah dengan
α = 5 % dan db = (n1 – 1) + ( n2 – 1 )
= ( 10 – 1 ) + ( 10 – 1 ) = 18
Maka nilai t tabel → t ( ......... ; 18 ) = ± ........
Perhitungan thitung
thitung =
=
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
Kedudukan thitung pada kurva distribusi t adalah sebagai berikut :
Milimeter Block
5 x 12 cm
Grafik 2.4 thitung pada kurva distribusi t
Sumber : Dokumentasi Pribadi (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
19
Kelompok xx
Pengujian Kekerasan dan Mikrostruktur
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
20
Kelompok xx
Pengujian Kekuatan Kejut
Grafik Cetak
19.5 x 11.5
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik 2.5 Hubungan Tingkat Kekerasan Perlakuan Panas dan Tanpa Perlakuan
2.5 Pembahasan
21
Kelompok xx
Pengujian Kekuatan Kejut
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
22
Kelompok xx
Pengujian Kekuatan Kejut
2.6 Kesimpulan dan Saran
2.6.1 Kesimpulan
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
1.6.2
Saran
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
23
Kelompok xx
Pengujian Kekuatan Kejut
BAB III
PENGUJIAN KEKUATAN KEJUT
3.1 Tujuan Pengujian
1. Mengetahui daya tahan suatu logam terhadap beban dinamis yang menyebabkan
terjadinya patahan.
2. Mengetahui bentuk patahan.
3. Mengetahui pengaruh perlakuan panas terhadap kekuatan kejut logam.
4. Mengetahui cara pengujian kekuatan kejut.
3.2 Definisi Kekuatan Kejut
........................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
3.3 Pelaksanaan Pengujian
3.3.1 Alat dan Bahan yang Digunakan
1.
Charpy Impact Testing Machine.
Digunakan untuk mengukur kekuatan kejut.
 Berat pendulum
: 24 Kgf
 Radius lengan
: 60 cm
 Sudut lengan
: 90°
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
24
Kelompok xx
Pengujian Kekuatan Kejut
Gambar 3.1 Charpy Impact Testing Machine
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
Keterangan Gambar:
2.
1.
Pendulum.
2.
Lengan pengikat
3.
Jarum penunjuk derajat
4.
Pemutar lengan
5.
Tuas sabuk rem
6.
Sabuk rem
7.
Tombol pengunci
Dapur Listrik
Dapur ini digunakan untuk proses pemanasan (heating), penahanan (holding),
dan pendinginan (cooling) dalam dapur. Seperti ditunjukkan pada gambar 2.3
3.
Tang penjepit
Digunakan untuk mengambil benda uji dari dapur listrik pada proses perlakuan
panas. Seperti ditunjukkan pada gambar 2.4.
4.
Bak pendingin
Digunakan sebagai tempat media pendingin spesimen pada perlakuan panas
5.
Stopwatch
Digunakan untuk mengukur waktu holding. Seperti ditunjukkan pada gambar 2.5
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
25
Kelompok xx
6.
Pengujian Kekuatan Kejut
Jangka Sorong
Digunakan untuk mengukur dimensi spesimen. Seperti ditunjukkan pada gambar
2.7.
7.
Kertas Gosok
Digunakan untuk membersihkan spesimen dari terak dan kotoran. Seperti
ditunjukkan pada gambar 2.6.
8.
Penggaris
Digunakan untuk mengukur dimensi spesimen. Seperti ditunjukkan pada gambar
2.8.

Komposisi Kimia Spesimen
- Spesimen : Bohler Special K
- Komposisi :
:
C =2%
Mn = 0,3 %
Si = 0,2 %
Cr = 12 %

Pergeseran Titik Eutectoid
Tabel 3.1 Komposisi Kimia
Unsur
Komposisi
No
Paduan
(%)
1
C
2
2
Mn
0.3
3
Si
0.2
4
Cr
12
Suhu Eutectoid
%C
Sumber: Dokumentasi Pribadi (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
26
Kelompok xx
Pengujian Kekuatan Kejut
Milimeter Block
10 x 10
Gambar 3.4 Grafik Pegeseran Titik Eutectoid
Sumber : Dokumentasi Pribadi (2016)

Bentuk dan Dimensi Spesimen
(LAMPIRAN)
3.3.2 Prosedur Pengujian
1.
Permukaan benda uji dibersihkan dari kotoran dan terak dengan kertas gosok.
2.
Spesimen dipanaskan dan di-holding dengan suhu dan waktu tertentu.
3.
Spesimen dipindahkan dari dapur listrik untuk proses pendinginan pada media
tertentu
4.
Spesimen dibersihkan dari kotoran dan terak.
5.
Dilakukan dry run test sebagai berikut:
 Pendulum alat uji Charpy diatur agar benar – benar menggantung bebas dan
dalam keadaan diam.
 Kedua jarum penunjuk diatur pada posisi vertikal.
 Lengan pengikat diturunkan dengan roda pemutar.
 Tombol pengunci ditekan selanjutnya jika kedudukan lengan pengikat sudah
tepat terhadap pendulum, pengunci dapat dilepas tanpa menggesar kedudukan
pendulum.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
27
Kelompok xx
Pengujian Kekuatan Kejut
 Pendulum beserta lengannya diangkat dengan roda pemutar sehingga jarum
luar menunjukkan skala yang sesuai dengan kedudukan pendulum dalam
posisi horizontal (90o).
 Dilakukan dry run test untuk mengetahui energi yang dilepas mesin karena
kerugian mekanik. Dilakukan pencatatan sudut yang ditunjuk oleh jarum.
6.
Dilakukan pengujian sebagai berikut :
 Spesimen diletakkan pada tempatnya sehingga bagian punggung takik tepat
pada posisi jatuhnya pendulum.
 Dilakukan pengujian seperti pada dry run test.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
28
Kelompok xx
Pengujian Kekuatan Kejut
3.4 Pengolahan Data
3.4.1 Data Kelompok
 Spesimen Tanpa Perlakuan
Radius lintasan ( R )
=………...
Berat pendulum ( G )
=………...
Luas penampang ( F 0 )
=………...
Sudut awal ( β )
=………...
Sudut dry run ( α0 )
=………...
Sudut akhir ( α₁ )
=…………
a. Energi yang Diperlukan Secara Ideal
A0= G x R x {cos (90° - α10) – cos β0}
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
b. Kerugian Energi Pada Alat
f = G x R x {cos (90° - α0°) – cos β° }
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
c. Energi Aktual yang Diperlukan
A = A0 – f
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
d. Energi yang Diperlukan Untuk Mematahkan Spesimen Tiap Satuan Luas
Penampang
Ak = A / F0
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
29
Kelompok xx
Pengujian Kekuatan Kejut
 Spesimen dengan Perlakuan ……
Radius lintasan ( R )
=………...
Berat pendulum ( G )
=………...
Luas penampang ( F 0 ) =………...
Sudut awal ( β )
=………...
Sudut dry run ( α0 )
=………...
Sudut akhir ( α₁ )
=…………
a. Energi yang Diperlukan Secara Ideal
A0= G x R x {cos (90° - α10) – cos β0}
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
b. Kerugian Energi Pada Alat
f = G x R x {cos (90° - α0°) – cos β° }
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
c. Energi Aktual yang Diperlukan
A = A0 – f
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
d. Energi yang Diperlukan untuk Mematahkan Spesimen Tiap Satuan Luas
Penampang.
Ak = A / F0
.............................................................................................................................
.............................................................................................................................
.............................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
30
Kelompok xx
Pengujian Kekuatan Kejut
Grafik Cetak
19.5 x 11.5
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik 3.1 Perbandingan Energi Patah dengan Tanpa Perlakuan dan Perlakuan ………
3.5 Pembahasan
31
Kelompok xx
Pengujian Kekuatan Kejut
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
32
Kelompok xx
Pengujian Kekuatan Kejut
3.6 Kesimpulan dan Saran
3.6.1 Kesimpulan
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
3.6.2 Saran
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
33
Kelompok xx
Pengujian Kekuatan Tarik
BAB IV
PENGUJIAN KEKUATAN TARIK
4.1
Tujuan Pengujian
1.
Mengetahui tegangan yield, tegangan ultimate, regangan dan kontraksi suatu
bahan.
2.
Mengetahui pengaruh perlakuan panas terhadap parameter di atas.
3.
Mengetahui cara pengujian tarik.
4.2
Definisi Kekuatan Tarik
................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
4.3
Pelaksanaan Pengujian
4.3.1 Alat yang Digunakan Dalam Pengujian
1.
Mesin Uji Tarik
Alat ini digunakan untuk memberikan beban tarik kepada spesimen.
Spesifikasi Mesin Uji Tarik:
Merk
: MFL Piuf – Und Me Bysteme GmbH D 6800 Mannheim
Kapasitas
: 100 kN
Tipe
: U PD 10
Tahun
: 1982
Mesin ini memiliki tiga skala pengukuran beban, yaitu :
A
: 0 – 20 kN
A+B
: 0 – 50 kN
A+B+C
: 0 – 100 kN
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
34
Kelompok xx
Pengujian Kekuatan Tarik
Keterangan Gambar :
1. Skala ukur pembebanan
2. Jarum pembebanan
3. Crane pengunci fluida
4. Crane pengatur
kecepatan tarik
5. Chuck lever
6. Chuck
7. Pengukur pertambahan
panjang specimen
Gambar 4.1 Mesin Uji Tarik
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
2.
Dapur listrik
Dapur ini digunakan untuk proses pemanasan (heating), penahanan (holding),
dan pendinginan (cooling) dalam dapur. Seperti ditunjukkan pada gambar 2.3.
3.
Tang penjepit
Digunakan untuk mengambil benda uji dari dapur listrik pada proses perlakuan
panas. Seperti ditunjukkan pada gambar 2.4.
4.
Bak pendingin
Digunakan sebagai tempat media pendingin spesimen pada perlakuan panas.
Seperti ditunjukkan pada gambar 2.5.
5.
Spidol
Digunakan untuk menandai spesimen.
Gambar 4.2 Spidol
Sumber : Laboratorium Pengujian Bahan Teknik Mesin Fakultas Teknik Universitas
Brawijaya (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
35
Kelompok xx
6.
Pengujian Kekuatan Tarik
Stopwatch
Digunakan untuk mengukur waktu holding. Seperti ditunjukkan pada gambar 2.5.
7.
Jangka Sorong
Digunakan untuk mengukur dimensi spesimen. Seperti ditunjukkan pada gambar
2.7
8.
Kertas Gosok
Digunakan untuk membersihkan spesimen dari terak dan kotoran. Seperti
ditunjukkan pada gambar 2.6.
9.
Penggaris
Digunakan untuk mengukur dimensi spesimen. Seperti ditunjukkan pada gambar
2.8.

Komposisi Kimia Spesimen
- Spesimen : Baja Esser (St - 37)
Komposisi :

C
= 0,16%
Mn
= 0,40%
Si
= 0,35%
P
= 0,035%
S
= 0,03%
Al
= 0,20%
Pergeseran Titik Eutectoid
Tabel 4.1 Komposisi Kimia
Unsur
Komposisi
No
Paduan
(%)
Suhu Eutectoid
%C
1
2
Sumber: Dokumentasi Pribadi (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
36
Kelompok xx
Pengujian Kekuatan Tarik
Milimeter Block
10 x 10 cm
Gambar 4.3 Grafik Pegeseran Titik Eutectoid
Sumber : Dokumentasi Pribadi (2016)

Bentuk dan Dimensi Spesimen
(LAMPIRAN)
4.3.2 Prosedur Pengujian
1. Permukaan benda uji dibersihkan dari kotoran dan terak dengan kertas gosok.
2. Spesimen dipanaskan dan di-holding dengan suhu dan waktu tertentu.
3. Spesimen dipindahkan dari dapur listrik ke bejana pendingin untuk proses
pendinginan pada media tertentu
4. Spesimen dibersihkan dari kotoran dan terak.
5. Dilakukan pengukuran dimensi spesimen, meliputi diameter awal dan panjang
awal. Kemudian spesimen dibagi ke dalam segmen – segmen dengan panjang
masing – masing 5 mm.
6. Spesimen dipasang dengan erat pada alat uji.
7. Alat uji diatur pada kecepatan angkat 1,8 liter / menit, dengan pembebanan pada
posisi A + B , skala pertambahan panjang 0 mm, dan jarum beban pada posisi nol.
8. Mesin dinyalakan, dan dilakukan pengamatan dengan teliti terhadap beban,
pertambahan panjang, dan perubahan diameter sampai spesimen patah.
9. Setelah patah, dilakukan pengukuran dimensi akhir spesimen.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
37
Kelompok xx
Pengujian Kekuatan Tarik
4.4 Pengolahan Data
4.4.1 Data Kelompok
a.
Spesimen Tanpa Perlakuan
Tabel 4.2 Data Hasil Pengujian Spesimen
Tanpa Perlakuan
ΔL
D
Beban
No.
(mm)
(mm)
(kN)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Sumber : Dokumentasi Pribadi (2016)
Tabel 4.3 Diameter Tiap Segmen Sebelum dan Sesudah Pengujian pada Spesimen
Tanpa Perlakuan
Sebelum Patah (mm)
Sesudah Patah (mm)
Sumber : Dokumentasi Pribadi (2016)
 Keterangan :
-
Diameter awal (Do)
= ….......
-
Diameter Ultimate (Du)
= ………
-
Diameter patah (Df)
= ………
-
Beban Yield (Py)
= ………
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
38
Kelompok xx
Pengujian Kekuatan Tarik
-
Beban Ultimate (Pu)
= ………
-
Beban patah (Pf)
= ………
-
Panjang awal (lo)
= ………
-
Panjang Ultimate (lu)
=………
-
Panjang akhir (lf)
= ………
 Perhitungan dan Pengolahan Data :
1. Luas Penampang
a. Luas penampang awal (Ao)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
b. Luas penampang Ultimate (Au)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
c. Luas penampang saat patah (Af)
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………….
……………………………………………………………………………
……………………………………………………………………………
2. Regangan
a. Regangan Ultimate rekayasa (ɛu)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
39
Kelompok xx
Pengujian Kekuatan Tarik
b. Regangan Ultimate sejati (ɛu’)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………..
…………………………………………………………………………..
c. Regangan patah rekayasa (ɛf )
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………..
…………………………………………………………………………..
……………………………………………………………………………
d. Regangan patah Sejati (ɛf’)
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………..
…………………………………………………………………………..
…………………………………………………………………………..
e. Regangan yield (ɛy)
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………..
…………………………………………………………………………..
…………………………………………………………………………..
3. Tegangan
a. Tegangan Ultimate rekayasa (σu)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
40
Kelompok xx
Pengujian Kekuatan Tarik
b. Tegangan Ultimate sejati (σu’)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
c. Tegangan patah rekayasa (σf)
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
d. Tegangan patah Sejati (σf’)
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
e. Tegangan yield (σy)
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
………………………………………………………………………
4. Kontraksi (Q)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
5. Modulus Elastisitas (E)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
41
Kelompok xx
Pengujian Kekuatan Tarik
……………………………………………………………………………
……………………………………………………………………………
Tabel 4.4 Hasil Pengolahan Data Spesimen Tanpa Perlakuan
No.
Panjang
(mm)
Beban
(N)
Diameter
(mm)
Luas
(mm²)
Teg.
Rekayasa
(N/mm²)
Teg.
Sejati
(N/mm²)
Reg.
Rekayasa
(%)
Reg.
Sejati
(%)
Kontraksi
(%)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Sumber : Dokumentasi Pribadi (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
42
Kelompok xx
Pengujian Kekuatan Tarik
b. Spesimen dengan Perlakuan ……
Tabel 4.5 Data Hasil Pengujian Spesimen
dengan Perlakuan ......
ΔL
D
Beban
No.
(mm)
(mm)
(kN)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Sumber : Dokumentasi Pribadi (2016)
Tabel 4.6 Diameter Tiap Segmen Sebelum dan Sesudah Pengujian dengan
Perlakuan….
Sebelum Patah
(mm)
Sesudah Patah
(mm)
Sumber : Dokumentasi Pribadi (2016)
 Keterangan :
- Diameter awal (Do)
= ….......
- Diameter Ultimate (Du)
= ………
- Diameter patah (Df)
= ………
- Beban Yield (Py)
= ………
- Beban Ultimate (Pu)
= ………
- Beban patah (Pf)
= ………
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
43
Kelompok xx
Pengujian Kekuatan Tarik
- Panjang awal (lo)
= ………
- Panjang Ultimate (lu)
=………
-
= ………
Panjang akhir (lf)
 Perhitungan dan Pengolahan Data :
1. Luas Penampang
a. Luas penampang awal (Ao)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
b. Luas penampang Ultimate (Au)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
c. Luas penampang saat patah (Af)
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………….
……………………………………………………………………………
……………………………………………………………………………
2. Regangan
a. Regangan Ultimate rekayasa (ɛu)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
44
Kelompok xx
Pengujian Kekuatan Tarik
b. Regangan Ultimate sejati (ɛu’)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………..
…………………………………………………………………………..
c. Regangan patah rekayasa (ɛf )
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………..
…………………………………………………………………………..
……………………………………………………………………………
d. Regangan patah Sejati (ɛf’)
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………..
…………………………………………………………………………..
…………………………………………………………………………..
e. Regangan yield (ɛy)
……………………………………………………………………………
……………………………………………………………………………
…………………………………………………………………………..
…………………………………………………………………………..
………………………………………………………………………
3. Tegangan
f. Tegangan Ultimate rekayasa (σu)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
45
Kelompok xx
Pengujian Kekuatan Tarik
g. Tegangan Ultimate sejati (σu’)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
h. Tegangan patah rekayasa (σf)
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
i. Tegangan patah Sejati (σf’)
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
j. Tegangan yield (σy)
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
…………………………………………………………………………
………………………………………………………………………
4. Kontraksi (Q)
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
5. Modulus Elastisitas (E)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
46
Kelompok xx
Pengujian Kekuatan Tarik
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
……………………………………………………………………………
Tabel 4.7 Hasil Pengolahan Data Spesimen Dengan Perlakuan …....
No.
Panjang
(mm)
Beban
(N)
Diameter
(mm)
Luas
(mm2)
Teg.
Rekayasa
(N/ mm2)
Teg.
sejati
(N/ mm2)
Reg.
Rekayasa
(%)
Reg.
Sejati
(%)
Kontraksi
(%)
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
Sumber : Dokumentasi Pribadi (2016)
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
47
Kelompok xx
Pengujian Kekuatan Tarik
4.5 Pembahasan
A. Grafik Hubungan Tegangan (rekayasa + Sejati) – regangan (rekayasa) dengan
Grafik Cetak
19.5 x 11.5 cm
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik 4.1 Tegangan (Rekayasa+sejati)-Regangan Spesimen Uji tanpa perlakuan
Spesimen Uji Tanpa Perlakuan
48
Kelompok xx
Pengujian Kekuatan Tarik
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
…………………………………………………………………………………………
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
49
Kelompok xx
Grafik Hubungan Tegangan (rekayasa + Sejati) – Regangan (rekayasa)
dengan Spesimen Uji dengan Perlakuan ……..
Grafik Cetak
19.5 x 11.5 cm
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik4.2 Hubungan Tegangan (rekayasa + Sejati) – Regangan (rekayasa) dengan Spesimen Uji Perlakuan ….
B.
Pengujian Kekuatan Tarik
50
Kelompok xx
Pengujian Kekuatan Tarik
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
………………………………………………………………………………………….
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
51
Kelompok xx
Pengujian Kekuatan Tarik
C. Grafik Hubungan Regangan (rekayasa + Sejati) – Kontraksi dengan Spesimen
Grafik Cetak
19.5 x 11.5 cm
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik 4.3 Hubungan Regangan (rekayasa + Sejati) –Kontraksi dengan spesimen Uji Tanpa perlakuan
Uji Tanpa perlakuan
52
Kelompok xx
Pengujian Kekuatan Tarik
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
………………………………………………………………………………………….
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
53
Kelompok xx
Pengujian Kekuatan Tarik
D. Grafik Hubungan Regangan (rekayasa + Sejati) – Kontraksi dengan Spesimen
Grafik Cetak
19.5 x 11.5 cm
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik 4.4 Hubungan Regangan (rekayasa + Sejati) – Kontraksi pada Spesimen Uji dengan Perlakuan ………
Uji dengan Perlakuan ………..
54
Kelompok xx
Pengujian Kekuatan Tarik
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
…………………………………………………………………………………………
………………………………………………………………………………………….
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
55
Kelompok xx
Pengujian Kekuatan Tarik
E. Grafik Hubungan Tegangan (rekayasa + Sejati) – Kontraksi dengan Spesimen
Grafik Cetak
19.5 x 11.5 cm
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik 4.5 Hubungan Tegangan (rekayasa + Sejati) – Kontraksi pada Spesimen Uji Tanpa perlakuan
Uji Tanpa Perlakuan
56
Kelompok xx
Pengujian Kekuatan Tarik
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.......................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
………………………………………………………………………………………….
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
57
Kelompok xx
Pengujian Kekuatan Tarik
F. Grafik Hubungan Tegangan (rekayasa + Sejati) – Kontraksi Spesimen
Grafik Cetak
19.5 x 11.5 cm
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik 4.6 Hubungan Tegangan (rekayasa + Sejati) – Kontraksi pada Spesimen Uji dengan Perlakuan ….
Perlakuan …….
58
Kelompok xx
Pengujian Kekuatan Tarik
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
………………………………………………………………………………………….
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
59
Kelompok xx
Pengujian Kekuatan Tarik
G. Diagram Pengukuran Besar Diameter Spesimen Sebelum dan Sesudah
Grafik Cetak
19.5 x 11.5 cm
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik 4.7 Hasil pengukuran besar diameter spesimen sebelum dan sesudah pengujian pada spsesimen tanpa
perlakuan
Pengujian pada Spesimen Tanpa Perlakuan
60
Kelompok xx
Pengujian Kekuatan Tarik
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
………………………………………………………………………………………….
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
61
Kelompok xx
Pengujian Kekuatan Tarik
Grafik
GrafikCetak
Cetak
19.5
19.5xx11.5
11.5cm
cm
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
Grafik 4.8 Hasil pengukuran besar diameter spesimen sebelum dan sesudah pengujian pada spesimen dengan
Perlakuan………
H. Diagram Pengukuran Besar Diameter Spesimen Sebelum dan Sesudah Pengujian
pada Spesimen dengan Perlakuan .......
62
Kelompok xx
Pengujian Kekuatan Tarik
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
………………………………………………………………………………………….
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
63
Kelompok xx
Pengujian Kekuatan Tarik
4.6 Kesimpulan dan Saran
4.6.1 Kesimpulan
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
4.6.2 Saran
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
64
Kelompok xx
Pengujian Kemampukerasan
BAB V
PENGUJIAN KEMAMPUKERASAN
5.1 Tujuan Penelitian
1.
Mengetahui kemampukerasan suatu bahan
2.
Mengetahui pengaruh suhu pemanasan terhadap kemampukerasan suatu bahan
3.
Mengetahui pengaruh waktu penahanan terhadap kemampukerasan suatu bahan
4.
Mengetahui cara menentukan kemapukerasan bahan
5.2 Sifat Kemampukerasan Baja
......................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
.........................................................................................................................................
5.3 Pelaksanaan Pengujian
5.3.1 Alat dan Bahan yang Digunakan
1.
Bejana pendingin (jominy)
Digunakan untuk mendinginkan benda uji dengan menyemprotkan air pada salah
satu ujung benda uji.
Keterangan Gambar
1. Penutup bejana Jominy
2. Kran aliran media pendingin
3. Pipa alir media pendingin
4. Saluran penyemprot
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
65
Kelompok xx
2.
Pengujian Kemampukerasan
Dapur listrik
Digunakan untuk memberikan perlakuan panas (heat treatment) pada benda uji.
Seperti ditunjukkan pada gambar 2.3.
3.
Kertas gosok
Digunakan untuk menghilangkan kotoran dan terak pada benda uji. Seperti
ditunjukkan pada gambar 2.6.
Tang penjepit
Digunakan untuk memindahkan benda uji setelah pemanasan dalam dapur listrik.
Seperti ditunjukkan pada gambar 2.4.
4.
Centrifugal Sand Paper Machine
Digunakan untuk menghaluskan benda kerja. Seperti ditunjukkan pada gambar
2.2.
6.
Rockwell Type Hardness Tester
Digunakan untuk mengukur kekerasan. Seperti ditunjukkan pada gambar 2.1.
7.
Stopwatch
Digunakan untuk mengukur waktu holding. Seperti ditunjukkan pada gambar 2.5.
8.
Jangka Sorong
Digunakan untuk mengukur dimensi spesimen. Seperti ditunjukkan pada gambar
2.7.
9.
Penggaris
Digunakan untuk mengukur dimensi spesimen. Seperti ditunjukkan pada gambar
2.8.
10. Spidol
Digunakan untuk menandai spesimen. Seperti ditunjukkan pada gambar 4.2

Komposisi Kimia Spesimen
- Spesimen
: Baja Assab 760
- Komposisi
:
C
= 0,50 %
Mn = 0,50 %
Si = 0,25 %
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
66
Kelompok xx

Pengujian Kemampukerasan
Pergeseran Titik Eutectoid
Tabel 2.1 Komposisi Kimia
Unsur
Komposisi
No
Paduan
(%)
1
C
0.50
2
Mn
0.50
3
Si
0.25
Suhu Eutectoid
%C
Sumber : Dokumentasi Pribadi (2016)
Milimeter Block
10 x 10
Gambar 2.7 Grafik Pegeseran Titik Eutectoid
Sumber : Dokumentasi Pribadi (2016)

Bentuk dan Dimensi Spesimen
(LAMPIRAN)
5.3.2 Prosedur Pengujian
1.
Permukaan benda uji dibersihkan dari kotoran dan terak dengan kertas gosok.
2.
Spesimen dipanaskan dan di-holding dengan suhu dan waktu tertentu.
3.
Spesimen dipindahkan dari dapur listrik ke bejana pendingin untuk proses
pendinginan. Pendinginan dimulai dari salah satu ujung batang.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
67
Kelompok xx
Pengujian Kemampukerasan
4.
Setelah pendinginan selesai, spesimen dibersihkan dengan kertas gosok.
5.
Haluskan permukaan benda kerja menggunakan centrifugal sand paper machine
sampai betul – betul rata dan halus dan siap diuji.
6.
Spesimen dibagi menjadi 10 bagian dengan jarak – jarak 2; 4; 6; 8; 10; 15; 20;
30; 40; 60 mm dari ujung yang disemprot dan ditandai menggunakan spidol.
7.
Kekerasan spesimen diukur dengan Rockwell Type Hardness Tester pada jarak –
jarak tersebut.
8.
Siapkan perangkat uji kekerasan Rockwell C pada Universal Hardness Tester:
a. Memasang bandul beban (1471 N).
b. Memasang indentor intan.
c. Memasang benda kerja pada landasan
d. Atur tuas pada posisi Unloading
9.
Putar turn wheel searah jarum jam secara perlahan hingga benda kerja
menyentuh indentor tanpa mengalami impact, sampai jarum besar berputar
sebanyak tiga kali pada skala C dan jarum kecil bergerak dari titik hitam
menunju pada titik merah.
10. Dorong tuas pembebanan ke arah loading secara perlahan – lahan. Tunggu
hingga jarum besar pada skala berhenti dengan sendirinya.
11. Tunggu selama 10 detik dari saat berhentinya jarum, kemudian gerakkan tuas ke
unloading secara perlahan-lahan sampai maksimal. Dengan naiknya tuas, jarum
ikut berputar searah putaran jarum jam sampai akhirnya berhenti.
12. Baca harga kekerasan HRC pada saat jarum telah berhenti. Bacalah pada skala C
yang berwarna hitam.
13. Ulangi langkah 8-12 sampai didapat nilai kekerasan dari 10 bagian spesimen
sesuai dengan jarak yang ditentukan.
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
68
Kelompok 15
Pengujian Kemampukerasan
5.4 Pengolahan Data
5.4.1 Data Kelompok
A. Spesimen Tanpa Perlakuan
Tabel 5.2 Data Tanpa Perlakuan
No
Xi
yi
(mm)
Ln Yi
Xi²
Xi LnYi
(HRC)
1
2
3
4
5
6
7
8
9
10
∑
Sumber : Dokumentasi Pribadi (2016)
Contoh Perhitungan
Persamaan:

Xi Ln Yi – a ∑Xi2 – b ∑Xi = 0
……a – …..b = …………

∑ Ln Yi – a∑ Xi – nb = 0
….a – …. b = ……….
Eliminasi
…..a – ……b = ……….
b
= ……..
a
= ………
Tabel 5.3 Data Tanpa Perlakuan
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
69
Kelompok 15
Pengujian Kemampukerasan
No
Xi
Yi
(mm)
= e ax + b
1
2
3
4
5
6
7
8
9
10
∑
Sumber : Dokumentasi Pribadi (2016)
Perhitungan
1. Ln Yn
= aXn + b
Ln Y1
= aX1+ b
Ln Y1
= ……..
Y1
= ……..
Persamaan:

Xi Ln Yi – a ∑ Xi²– b ∑Xi = 0
..................................................................................................................................

∑ Ln Yi – a∑ Xi – nb = 0
...................................................................................................................................
Eliminasi
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.........................................................................................................................
Jumlah Kuadran Deviasinya
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
70
Kelompok 15
δ
Pengujian Kemampukerasan
= [ ln Y1 – ( ax1 + b ) ]2 + [ ln Y2 – ( ax2 + b ) ]2 + … + [ ln Y10 – ( ax10 + b)]2
.............................................................................................................................................
.............................................................................................................................................
.................................................................................................................................
B. Spesimen dengan Perlakuan ……
Tabel 5.4 Data Spesimen dengan Perlakuan ……
No
yi
Xi
Ln Yi
Xi²
(HRC)
Xi LnYi
(mm)
1
2
3
4
5
6
7
8
9
10
∑
Sumber : Dokumentasi Pribadi (2016)
Contoh Perhitungan
Persamaan:

Xi Ln Yi – a ∑Xi2 – b ∑Xi = 0
……a – ……..b = ………….

∑ Ln Yi – a∑ Xi – nb = 0
…..a – …… b = ………..
Eliminasi
…..a – ……b = ……….
b
= ……..
a
= ………
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
71
Kelompok 15
Pengujian Kemampukerasan
Tabel 5.5 Data Tanpa Perlakuan
No
Xi
Yi
(mm)
1
2
3
4
5
6
7
8
9
10
∑
Sumber : Dokumentasi Pribadi (2016)
Perhitungan
2. Ln Yn
= aXn + b
Ln Y1
= aX1+ b
Ln Y1
= ………… + ………..
Ln Y1
= …………..
Y1
= …………….
Persamaan:

Xi Ln Yi – a ∑ Xi²– b ∑Xi = 0
..................................................................................................................................

∑ Ln Yi – a∑ Xi – nb = 0
..................................................................................................................................
Eliminasi
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
72
Kelompok 15
Pengujian Kemampukerasan
.............................................................................................................................................
..........................................................................................................................................
Jumlah Kuadran Deviasinya
δ
= [ ln Y1 – ( ax1 + b ) ]2 + [ ln Y2 – ( ax2 + b ) ]2 + … + [ ln Y10 – ( ax10 + b)]2
.............................................................................................................................................
.............................................................................................................................................
...........................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
73
Kelompok 15
Pengujian Kemampukerasan
5.5 Pembahasan
A. Hubungan Antara Jarak Penyemprotan dan Kekerasan pada Spesimen Tanpa
Grafik 5.1 Hubungan Antara Jarak Penyemprotan dan Kekerasan Spesimen Tanpa Perlakuan
Perlakuan
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
74
Kelompok 15
Pengujian Kemampukerasan
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.....................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
..........................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
75
Kelompok 15
Pengujian Kemampukerasan
5.6 Kesimpulan dan Saran
5.6.1 Kesimpulan
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.....................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................
.........................................................................................................................................
5.6.2 Saran
.............................................................................................................................................
.............................................................................................................................................
..................................................................................................................................……..
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................
.............................................................................................................................................
............................................................................................................................................
LABORATORIUM PENGUJIAN BAHAN
Laporan Semester Genap 2015/2016
76