This is my Lab Report of Tensile Test when I was conducting engineering material lab in Sampoerna University. Feel free to download for a reference. I know it is not a good report, but I hope this share might help you to find something you need. Thank you.

1. 0
Lab Report
Engineering Materials Lab
Module A: Tensile Test
Name : Muhammad Yossi Hadiyoso
Student Number : 2014 31 0003
Lab Date : Saturday, March 4th 2017
Report Handover Date : Friday, March 10th 2017
Materials Engineering Laboratory
Applied Physics Study Program
Faculty of Science and Technology
Sampoerna University
2017

2. 1
Abstract
The mechanical properties of material can be observed through tensile test. It gives
the the characteristic of tensile strength, yield strength, modulus of elasticity, ductility,
recilience, and toughness. These characteristics might useful for material testing reference.
In this experiment, the two unknown steel are being tested using tensile test machine. The
result are being computed. The similarity of mechanical properties of the specimens are
being compared to the exist material on the data sheet.

3. 2
Table of Content
Cover.............................................................................................................................................
Abstract....................................................................................................................................... 1
Table of Content........................................................................................................................... 2
List of Figures and Tables.............................................................................................................. 3
Chapter 1: Introduction................................................................................................................. 4
1.1 Background......................................................................................................................... 5
1.2 Experiment Objective .......................................................................................................... 5
Chapter 2: Fundamental Theory.................................................................................................... 5
2.1 Tensile Test......................................................................................................................... 5
2.1.1 Specimen ..................................................................................................................... 5
2.2 Mechanical Propertiesfrom Tensile Test............................................................................... 5
2.2.1 Yield Strength............................................................................................................... 5
2.2.2 Tensile Strength............................................................................................................ 5
2.2.3 Modulus of Elasticity..................................................................................................... 6
2.2.4 Modulus of Resilience................................................................................................... 6
2.2.5 Modulus of Resilience................................................................................................... 6
Chapter 3: Experimental Method................................................................................................... 7
3.1 Apparatus ........................................................................................................................... 7
3.2 Procedure........................................................................................................................... 7
3.3 Experimental Data............................................................................................................... 7
Chapter 4: Discussion and Analysis ...............................................................................................10
Chapter 5: Conclusions and Recommendations .............................................................................19
References..................................................................................................................................20
Appendix.....................................................................................................................................21

4. 3
List of Figures and Tables
Figure
1. Figure 1 Tensile test machine................................................................................................. 5
2. Figure 2 The standard specimen dimension of tensile test ....................................................... 5
3. Figure 3 Initial dimension of specimens used on the experiment.............................................. 7
4. Figure 4 Force vs time: Specimen A......................................................................................... 8
5. Figure 5 Force vs time: Specimen B......................................................................................... 8
6. Figure 6 Engineering stress-strain curve andits yield strength ................................................10
7. Figure 7 Force vs elongation curve of the specimens ..............................................................13
8. Figure 8 Engineering Stress-strain curve of the specimens ......................................................14
9. Figure 9 True stress-strain curve of the specimens..................................................................15
10. Figure 10 Logaritmic plot of true stress-strain curve .............................................................15
11. Figure 11 Engineering-True stress-strain plot........................................................................17
Tabel
1. Table 1 Data measurement.................................................................................................... 7
2. Table 2 DataCalculation from Specimen A .............................................................................. 9
3. Table 3 DataCalculation from Specimen B .............................................................................. 9

5. 4
Chapter 1: Introduction
1.1. Background
Metals have its own properties including physical, mechanical, and thermal
characteristic. The most important properties is the mechanical properties, which is
including ductility, hardness, strength, and toughness. The mechanical properties is the
measurements that used as a reference for material selection. To know the mechanical
properies of metals, it needs material testing. One of the material testing is the tensile test.
Tensile test is a measurement that examine the strength of material within giving
loads in unaxial direction to the specimen. The tested specimen is exposed by the increasing
unaxial force continuously while its change on elongation is being observed. The tensile test
measures the resistant of a material to the given static load. The results that generated from
the tensile test shows the mechanical properties of the specimen. The mechanical
properties of material that can be known from tensile test including:
- tensile strength
- yield strength
- modulus of elasticity
- ductility
- resilience
- toughness
Furthermore, the stress strain curve which is can be obtained from the measurement,
which allows one to compute the mechanical properties above.
The tensile test is very important because it tells the impact of load given to the
material’s mechanical properties of a material. These mechanical properties parameters
would provide the basic data if the strength of an material, in this experiment is metal.
1.2. Experiment Objectives
- To evaluate the mechanical properties of the specimen through an
understanding of curve result of tensile test.

6. 5
Chapter 2: Fundamental Theory
2.1. Tensile Test
Tensile test is a method used to measure the strength of an material by giving a
static load on unaxial direction of the specimen. The following is the scheme of tensile test:
Figure 1 Tensile test machine
The specimen that being tested is given some force in two directions, which is in
unaxial direction. The specimen would experience a stretch and an elongation until it
fracture or break. Moreover, the specimen size is standardized by some standard. For
example, the Indonesian tensile test specimen standard SNI 07-0371-1998, the standard
American Society for Testing and Materials (ASTM) E8 & E8M.
2.1.1. Specimen
The standard specimen by ASTM is the following:
Figure 2 The standard specimen dimension of tensile test
From the ASTM standard, the dimensions of the specimen of tensile test is looks like
above. The reduction section A, 2.25 inch, the diameter D, 0.505 inch, the gauge length G, 2
inch, and the radius R, 0.375 inch. Or diameter D : gauge length G is 1:4.
2.2. Mechanical Properties from Tensile Test
2.2.1. Yield Strength
Yield strength determine the stress of the material due to elastic limit. It is the
maximum load that obtained by the material when it is in between of elastic deformation
and plastic deformation.
2.2.2.Tensile Strength

7. 6
It is the maximum load that can be hold by the specimen before it experiencing
necking phenomenon. Necking happens when the gage of the specimen is starting to
decrease. The tensile strength happens in the plastic regime.
2.2.3. Modulus of Elasticity
Modulus of elasticity of young modulus is a measurement of resistant of the material
due to elastic deformation. It shows the stiffness of a material.
2.2.4. Modulus of Resilience
It is the properties that shows maximum energy that can be absorbed by the
material until the elastic limit. It is the area below the elastic deformation of stress-strain
curve.
2.2.5. Toughness
Toughness measures the energy that is needed for material to fracture.

8. 7
Chapter 3: Experimental Method
3.1. Apparatus
The apparatus that is used in the experiment are:
- Tensile Machine (TEST RESOURCES 313 Q:1)
- Vernier Caliper
- Stopwatch
- 2 unknown steel specimens with the same initial dimensions:
Figure 3 Initial dimension of specimens used on the experiment
3.2. Procedure
The procedure of the tensile test experiment:
- Prepare tensile test specimen
- Determine the initial dimension of the specimen (diameter, gage length)
- Prepare tensile test machine
- Record the testing parameters
- Put the specimen into the machine
- Test the material
- Measure the time until the specimen is break
- Take the specimen from the machine
- Measure the final diameter and gage length
- Repeat the test for the other specimen
3.3. Experiment Data
- Machine Type : TEST RESOURCES 313 Q:1
Maximum load capacity : 50,000 N
Test rate : 3 mm/min  0.05 mm/s
- Data measurement:
Specimen A Specimen B
Maximum load capacity 17,426.8 N 14,660.2 N
Initial length, Lo 35 mm 35 mm
Initial diameter, do 6.1 mm 6.1 mm
Final length, Lf 44.9 mm 46.5 mm
Final diameter, df 4.0 mm 3.6 mm
Total testing duration 225 seconds 220 seconds
Table 1 Data measurement

9. 8
- Data from machine:
Figure 4 Force vs time: Specimen A
Figure 5 Force vs time: Specimen B

10. 9
Data for plottingrandompoints:
Table 2 DataCalculation from Specimen A
Table 3 DataCalculation from Specimen B
Force (N) Time (s) Elongation (t*0.05mm/s) Engineering Stress (MPa) Engineering Strain True Stress (Mpa) True Strain
0 0 0 0.00E+00 0 0 0
1500 5 0.25 5.13E+07 0.007142857 51692533.3 0.007117468
5000 10 0.5 1.71E+08 0.014285714 173530490 0.014184635
9250 20 1 3.17E+08 0.028571429 325552975.7 0.028170877
11250 25 1.25 3.85E+08 0.035714286 398692411.1 0.03509132
11750 30 1.5 4.02E+08 0.042857143 419283881.2 0.041964199
11500 32.5 1.625 3.93E+08 0.046428571 411768300.1 0.045383006
12000 35 1.75 4.11E+08 0.05 431137724.6 0.048790164
14250 50 2.5 4.88E+08 0.071428571 522424538.7 0.068992871
15250 60 3 5.22E+08 0.085714286 566540388.6 0.082238098
16000 70 3.5 5.47E+08 0.1 602224123.2 0.09531018
16750 85 4.25 5.73E+08 0.121428571 642734938.3 0.114603383
17250 100 5 5.90E+08 0.142857143 674569228.9 0.133531393
17500 132.5 6.625 5.99E+08 0.189285714 712147134.3 0.173352887
17250 170 8.5 5.90E+08 0.242857143 590248075.3 0.217412877
17000 180 9 5.82E+08 0.257142857 581693755.3 0.228841572
16500 190 9.5 5.65E+08 0.271428571 564585115.5 0.240141128
16250 195 9.75 5.56E+08 0.278571429 556030795.6 0.245743383
16000 200 10 5.47E+08 0.285714286 547476475.6 0.251314428
15000 210 10.5 5.13E+08 0.3 513259195.9 0.262364264
13250 220 11 4.53E+08 0.314285714 453378956.4 0.273293335
12697.1 222.5 11.125 4.34E+08 0.317857143 1010432914 0.844029753
Steel A
Force (N) TIME Elongation (t*0.05mm/s) Engineering Stress (MPa) Engineering Strain True Stress (Mpa) True Strain
0 0 0 0 0 0 0
2250 5 0.25 76988879.38 0.007142857 77538799.95 0.007117468
7500 15 0.75 256629597.9 0.021428571 262128803.6 0.021202208
9375 20 1 320786997.4 0.028571429 329952340.2 0.028170877
10125 22.5 1.125 346449957.2 0.032142857 357585848.7 0.031637085
9750 25 1.25 333618477.3 0.035714286 345533423 0.03509132
10312.5 30 1.5 352865697.2 0.042857143 367988512.8 0.041964199
9937.5 32.5 1.625 340034217.3 0.046428571 355821520.2 0.045383006
11250 40 2 384944396.9 0.057142857 406941219.6 0.055569851
12187.5 50 2.5 417023096.7 0.071428571 446810460.7 0.068992871
12937.5 60 3 442686056.5 0.085714286 480630575.6 0.082238098
13687.5 75 3.75 468349016.3 0.107142857 518529268 0.101782694
14062.5 85 4.25 481180496.2 0.121428571 539609556.4 0.114603383
14437.5 100 5 494011976 0.142857143 564585115.5 0.133531393
14625 117.5 5.875 500427716 0.167857143 584428082.6 0.155170568
14660.2 142.5 7.125 501632164.2 0.203571429 603750140.5 0.185293327
14625 167.5 8.375 500427716 0.239285714 500427716 0.214535177
14437.5 175 8.75 494011976 0.25 494011976 0.223143551
14062.5 185 9.25 481180496.2 0.264285714 481180496.2 0.23450731
13312.5 195 9.75 455517536.4 0.278571429 455517536.4 0.245743383
12375 205 10.25 423438836.6 0.292857143 423438836.6 0.256854609
11062.5 215 10.75 378528657 0.307142857 378528657 0.26784373
10312.5 220 11 352865697.2 0.314285714 1013214777 1.054795979
Steel B

11. 10
Chapter 4: Discussion and Analysis
From the tensile test result, the two unknown steel specimens gives its own
mechanical properties measurement value.
Figure 6 Engineering stress-strain curve and its yield strength
By approximation plot from the engineering stress-strain plot of each specimen, the
yield strength σy of steel A is 400 Mpa and σy of steel B us 350 Mpa. It is quite lower than the
data sheet of steel, which is exactly 301, 304, and 310 stainless steels. However, the nearest
value of yield strength of those specimens is close to the 304 stainless steel. The 304
stainless steel has a yield strength about 470-1000 Mpa (Rowlands, David P., n.d.). And the
specimens has the value around 400 Mpa, for the largest. The different value perhaps
comes from the approximation data plotting when it is convert from the force-time curve to
the engineering stress-strain curve. Such that, the reading of plotting might contributes
error.
For the tensile strength σu of the specimens, steel A has the engineering tensile
strength about 599 Mpa, and steel B about 501 Mpa. However, its true stress value gives
the closer value to the 304 stainless steel’s tensile strength. The true tensile strength of
steel A is about 712 Mpa, and steel B about 603 Mpa, where the 304 stainless steel has 685-
1100 Mpa of tensile strength (Rowlands, David P., n.d.). From these experimental data
(value of true stress of tensile strength), steel A and steel B maybe have similar composition
to the 304 stainless steel, because the value of yield strength and tensile strength are close.
But the yield strength and tensile strength are not enough to evaluate these specimens to
what kind of steel is.
Then, for the elongation of the specimen, steel A has elongate about 11.125 mm and
steel B about 11 mm, where both steel A and steel B experienced 31% elongation at break.
According to the ASM Aerospace Specification Metal Inc. (n.d.), the elongation of 304
stainless steel is about 70% at break. Perhaps, the difference comes from the size of the
specimen from this experiment to the ASM. The ASM states that its elongate about 70% at
break in 50 mm. The ASM does not mention what is the meaning of 55 mm. It is unclear,

12. 11
evenmore the percent elongation is very far. However, according to American Metals Co.,
the 304 stainless steel has 40% elongation minimum, where the specimen dimension is
using the standard ASTM. These value is not too far to this experiment.
In addition, during the tensile test, the specimen is being strecthed and it is elongate.
While the length is getting longer, the area of speciment is being narrower. The percent
reduction of the area, q, then given by:
𝑞 =
𝐴 𝑜 − 𝐴𝑓
𝐴 𝑜
where Ao is the initial cross section area, and Af is the final cross section area. Both steel A
and B has an Ao about 29.225 mm2. The Af of steel A is 12.566 mm2 and steel B is 10.178
mm2. Therefore,
𝑞 𝑠𝑡𝑒𝑒𝑙 𝐴 =
29.225 − 12.566
29.225
= 0.57 → 57% 𝑜𝑓 𝑎𝑟𝑒𝑎 𝑟𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛
𝑞 𝑠𝑡𝑒𝑒𝑙 𝐵 =
29.225 − 10.178
29.225
= 0.65 → 65% 𝑜𝑓 𝑎𝑟𝑒𝑎 𝑟𝑒𝑑𝑢𝑐𝑡𝑖𝑜𝑛
Steel A experienced the lower reduction of area than steel B, but steel A got more
elongation than steel B. The (engineering) strain of steel A is about 0.317 while steel B is
0.314. It shows that the composition of these two steel probably are same.
The Young Modulus, E, of the specimen, the elasticity of the steel specimens, are
described from the ratio of stress and strain before its yield strength. Therefore, taking
engineering value before yield strength:
𝐸𝑠𝑡𝑒𝑒𝑙 𝐴 =
σ 𝑒𝑛𝑔𝑖𝑛𝑒𝑒𝑟𝑖𝑛𝑔
ε 𝑒𝑛𝑔𝑖𝑛𝑒𝑒𝑟𝑖𝑛𝑔
=
4.02𝐸 + 08 𝑁
0.042857143 𝑚2
= 9.38 × 109
𝑃𝑎
𝐸𝑠𝑡𝑒𝑒𝑙 𝐵 =
σ 𝑒𝑛𝑔𝑖𝑛𝑒𝑒𝑟𝑖𝑛𝑔
ε 𝑒𝑛𝑔𝑖𝑛𝑒𝑒𝑟𝑖𝑛𝑔
=
352865697.2 𝑁
0.042857143 𝑚2
= 8.23 × 109
𝑃𝑎
Steel A has 9.38 GPa of elastic modulus, while steel B has 8.23 GPa. However,
modulus of elasticity of steel generally is aroud 200 GPa. This is a big different with general
steel’s elastic modulus. This big difference perhaps because of the reading when converting
the force-time curve to the stress-strain curve.
Futhermore, when the specimen is stretched until its yield strength, it means it
starting to began transform to the plastic deformation, thereby, achieving the limit of elastic
deformation. When it achieved the limit, the modulus of resilience is being determined. The
modulus of resilience tells the maximum energy that can be absorbed until the elastic limit.
The modulus of resilience, Ur, is given by:
𝑈𝑟 =
1
2
σy εy
where the specimen yield strength and yield strain are:

13. 12
Hence, the modulus of resilience:
𝑈𝑟−𝑠𝑡𝑒𝑒𝑙 𝐴 =
1
2
(4.00 × 𝑒8)(0.048) = 9.6 × 106
𝐽𝑚−3
𝑈𝑟−𝑠𝑡𝑒𝑒𝑙 𝐵 =
1
2
(3.5 × 𝑒8)(0.035) = 6.125 × 106
𝐽𝑚−3
It shows how much the energy per surface of the elastical deformation of the specimen.
In other hand, when it is come to fracture, the toughness is measured. Toughness
describes the energy of mechanical deformation per unit volume until it is fracture, or it
measures the required energy for fracture. Therefore, it described as:
𝑈𝑡 =
σy + σu
2
× εf
where εy is the strain when it is fracture. Then, the specimen toughness are:
𝑈𝑡− 𝑠𝑡𝑒𝑒𝑙 𝐴 =
4.00 × 𝑒8
+ 599 × 106
2
× 0.317 = 1.58 × 108
𝐽𝑚−3
𝑈𝑡− 𝑠𝑡𝑒𝑒𝑙 𝐵 =
3.5 × 𝑒8
+ 501 × 106
2
× 0.314 = 1.34 × 108
𝐽𝑚−3
The toughness of steel A is greater than steel B. It means the specimen A could
absorb more energy to do mechanical deformation until its fracture. The steel B is more
fracture perhaps because the composition that build up this specimen is more brittle. It is
shown from the plot of stress-strain curve that the stress and strain of steel B is lower than
steel A.
The plot of the force vs elongation curves of the specimen that can be obtained
through experiment are the following:

14. 13
Figure 7 Force vs elongation curve of the specimens
This curve is obtained by converting the time axis from the experimental data to its
elongation. The plots are the appoximation plot, which is by random picking of 21 points for
steel A, and 23 points for steel B. The previous data of x-axis is in the form of time interval of
testing duration until it fracture was recorded on the experiment. To make this axis as
elongation, it needs to be converted. Besides, the speed of the tensile test’s strecthing is
been determined from the first, where the test duration for steel A is 225 seconds, while for
steel B is 220 seconds. The speed of the test machine is 0.05 mm/s. Hence, the final
elongation can be obtained by calculating the following:
𝑒𝑙𝑜𝑛𝑔𝑎𝑡𝑖𝑜𝑛 𝑠𝑡𝑒𝑒𝑙 𝐴 = 𝑟𝑎𝑡𝑒 𝑥 𝑡𝑖𝑚𝑒 = 0.05 × 225 = 11.25 𝑚𝑚
𝑒𝑙𝑜𝑛𝑔𝑎𝑡𝑖𝑜𝑛 𝑠𝑡𝑒𝑒𝑙 𝐵 = 𝑟𝑎𝑡𝑒 𝑥 𝑡𝑖𝑚𝑒 = 0.05 × 220 = 11 𝑚𝑚
That is the elongation based on the data obtained from the machine. However, the
measured final elongation using vernier caliper is the following:
𝑒𝑙𝑜𝑛𝑔𝑎𝑡𝑖𝑜𝑛 𝑒𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙𝑙𝑦− 𝑠𝑡𝑒𝑒𝑙 𝐴 = 𝐿 𝑓 − 𝐿 𝑖 = 44. 9 − 35 = 9.9 𝑚𝑚
𝑒𝑙𝑜𝑛𝑔𝑎𝑡𝑖𝑜𝑛 𝑒𝑥𝑝𝑒𝑟𝑖𝑚𝑒𝑛𝑡𝑎𝑙𝑙𝑦− 𝑠𝑡𝑒𝑒𝑙 𝐵 = 𝐿 𝑓 − 𝐿 𝑖 = 46. 5 − 35 = 11.5 𝑚𝑚
The different of elongation is quite far for steel A, which is about 1.35 mm length
difference. The measurement of test duration might be not very accurate and it deviate just
a little bit second. Moreover, the fracture is happen sunddenly. Perhaps the one that record
the final time test duration is too late a little bit. Thereby, affecting the convertion from
time axis to elongation axis.
The plot of the engineering stress vs engineering strain curves of the specimen that
can be obtained through experiment are the following:

15. 14
Figure 8 Engineering Stress-strain curve of the specimens
This curve is obtained by converting the force to the engineering stress and the
elongation to the engineering strain. By previous force vs elongation curve, the data then is
able to be converted to the engineering stress-strain by the following:
𝜎𝑒𝑛𝑔𝑖𝑛𝑒𝑒𝑟𝑖𝑛𝑔 =
𝐹
𝐴0
𝑒 𝑒𝑛𝑔𝑖𝑛𝑒𝑒𝑟𝑖𝑛𝑔 =
∆𝐿
𝐿 𝑜
where the A0 is the initial area, ∆L is the elongation, and Lo is the initial length of the
specimen. Both steel A and steel B shows almost similar curve. The curve is similar to tensile
test curve for metal, yes, because they are steel.
In addition, the curve shows the the leaning line when it pass the yield strength
position. The curve is getting lean beyond its yield strength. This line is showing the strain
hardening phenomena. It happens when elastic limit is passed. The material is begin to
experience plastic deformation by strengthening it. It is strengthened because the
dislocation is moving. It makes the material is more stronger, but the ductility is decrease.
The material would continue to deform plastically through the movement of dislocation,
stretching the bonds of its atoms until the fracture is happen.
On the other hand, there is a jumping back line on the curve, increase-and-decrease,
upper and lower yielding, when it is across the yield strength position. Here, the material
has finished its elastic deformation. However, the dislocation is still continue as the given
force is still going. The dislocation is actually meet the resistant that hold up the moving of
dislocation. The resistant is might be the impurities that present on that material which is
spread on the grain. Let say the impurities of these steel specimen is carbon. When the
dislocation meets carbon impurities, then the higher stress is needed to pass the impurities.
After the carbon impurities is passed, the energy that needed to move the dislocation is
getting low. Then, it makes the stress curve is going down. When the dislocation is meet the
carbon impurities again, the same thing would happen until all the impurities is passed, and

16. 15
the dislocation keep happen until its plastic deformation. The number of carbon atom inside
these steel not large, hence it can bee observed through the upper and lower yielding of
the stress. This phenomenon is called cottrell phenomenon.
Another plot that can be obtained is the true stress-strain curve, which is the
following:
Figure 9 True stress-strain curve of the specimens
From this curve, the true stress at maximum load can be obtained. For steel A, the
true stress at maximum load is 712 MPa, while the steel B is 603 MPa. The specimen A has
higher true stress than specimen B. It means, the energy required to fracture for steel A is
higher than steel B.
From the true stress-strain curve, the strength coefficient can be obtained by taking
a linear regression of logaritmic plot of these curve:
Figure 10 Logaritmic plot of true stress-strain curve
The strength coefficient can be generated from the formula:
𝜎𝑡𝑟𝑢𝑒 = 𝐾𝜀 𝑛

17. 16
where σtrue is the true stress, ε is the true strain, n is the strain hardening exponent, ε is the
true strain, and K is the strength coefficient. The value of n is lies between 0 to 1. 0 means
the material is a prefectly plastic solid, 1 means it prefectly elastic solid. Most metal have an
n between 0.1 until 0.5. Then,
the logaritmic form of the above simple power equation:
log (𝜎𝑡𝑟𝑢𝑒) = log(𝐾. 𝜀 𝑛
)
or it can be written as:
log(𝜎𝑡𝑟𝑢𝑒 ) = 𝑛 log ( 𝜀)+ log 𝐾
It is same as the:
𝑦 = 𝑚𝑥 + 𝑐
Which is similar to the linear regression equation from the curve above. Hence we can
compute the value of n and K of the specimen.
Specimen A:
𝑦 = 0.6003𝑥 + 9.3535
𝑦 = log(𝜎𝑡𝑟𝑢𝑒) = log(712 𝑥 106
𝑃𝑎) = 8.85
0.6003𝑥 = 𝑛 log (0.173) = −0.76𝑛
Then,
8.85 = −0.76𝑛 + 9.3535
𝑛 = 0.659
log 𝑘 = 9.3535
109.3535
= 𝑘
𝑘 = 2.256 GPa
Specimen B:
𝑦 = 0.4489𝑥 + 9.1376
𝑦 = log(𝜎𝑡𝑟𝑢𝑒) = log(603 𝑥 106
𝑃𝑎) = 8.78
0.4489𝑥 = 𝑛 log (0.185) = −0.73𝑛

18. 17
Then,
8.78 = −0.73𝑛 + 9.1376
𝑛 = 0.48
log 𝑘 = 9.1376
109.1376
= 𝑘
𝑘 = 1.373 GPa
From the calculation of both specimen, the value of its strain hardening n exponent
is close to the 304 stainless steel material, which has an n about 0.43. However, the value of
K of both specimen are different. Steel A has 2.256 GPa of K, which is quite same with 4340
steel alloy with the K about 2.650 GPa. While steel B has K about 1.373 GPa, which is very
close to the value of K of 304 stainless steel with 1.400 GPa of K. From here, steel A could be
catagorized to have a same composition with the 4340 steel alloy because of this strength
coefficient. While steel B is almost similar with the strength coefficient of the 304 stainless
steel.
Comparison of Engineering Stress-strain and True Stress-strain
Figure 11 Engineering-True stress-strain plot
The above curve shown the comparison of true and engineering stress-strain curves. The
engineering stress-strain curve shows the deformation characteristic of the specimen, where it is
based on the original known dimensions. Hence, the plot is based on the initial value, while
actually the dimensions is changing over the given tensile load. Contrary, the true stress-strain
curve shows a true value of the deformation changing. It consider the changing of the dimension.
That is why the true stress-strain plot is important.
Why the difference composition of steel has almost similar young modulus, E?

19. 18
The young modulus or modulus of elasticity is a measurement of resistant to the
separation adjacent of atoms in the material, in this case is iron atoms, Fe – Fe bonding. In the
steel, the addition of carbon solid solution is very small, which is less than 2%. It is spread out in
the interstitial of steel as the impurities. The present of carbon impurities affecting the bonding of
Fe – Fe atoms. So that, the bonding beetween Fe in the steel is determine its young modulus.
The Fracture Shape
The specimen’s fracture are in the form of cup-cone with the fracture angle around 45o. It
shows that the specimens experience rupture or ductile rupture.

20. 19
Chapter 5: Conclusions and Recommendations
Conclusions
From the tensile test experiment using tensile test machine, the mechanical
properties of a material can be obtained. When the material is being streched, it
experiencing elastic and plastic deformation. The strain hardening phenomenon is occur
when the material is getting strengthened until it goes to fracture.
For this experiment, the specimen steel A and steel B gives two different mechanical
properties. Eventhough both’s characteristic are almost same, steel A and steel B have a
different strength coefficient. Steel A is almost similar to the 4340 steel alloy, while steel B is
behave like 304 stainless steel.
The value that obtain that from this experiment is actually not accurate. It is because
of the approximation of plot from the raw data that generated by the machine.
Recommendations
For further experiment, it is better to obtain the data of stress-strain directly from
the machine. It is for increasing the accuracy of the analysis.

21. 20
References
304 Stainless Steel TechnicalData Sheet. (t.thn.). Diambil kembali dari
https://www.metalshims.com/t-304-Stainless-Steel-technical-data-
sheet.aspx
ASMMaterial Data Sheet. (t.thn.). Diambil kembali dari
http://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MQ304
A
Batang Uji Tarik untuk Bahan Logam. (1998). Standar NasionalIndonesia.
Indonesia.
Callister, W. D. (2009). MaterialScience and Engineering.USA: John Wuley &
Sons, Inc.
Dieter, G. E. (1988). MechanicalMetallurgy. British Library.

22. 21
Appendix
Specimen A fracture
Specimen B fracture