See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/324654226
The Tensile Test of Steel and Aluminum Laboratory Report
Preprint · December 2017
DOI: 10.13140/RG.2.2.17473.86884
CITATIONS
READS
0
4,932
1 author:
Regina Widera
University of Westminster
1 PUBLICATION 0 CITATIONS
SEE PROFILE
All content following this page was uploaded by Regina Widera on 20 April 2018.
The user has requested enhancement of the downloaded file.
The Tensile Test of Steel and
Aluminum
LABORATORY REPORT
Regina K. Widera | 11 December 2017
Objectives
The aim of this investigation is to obtain a tensile profile of four different samples of
metals.
The materials to be investigated are:
•
Low-carbon [0.1%] carbon steel
•
Medium-carbon [0.4%] steel
•
High-carbon [1.0%] steel
•
Aluminium alloy
Figure 1 shows the photography of the test pieces:
Figure 1
PAGE 1
For the steel specimens, the following material properties are going to be determined:
•
Yield stress value
•
Ultimate tensile stress value
•
Ductility parameters
For the aluminium alloy specimen, the following material properties are going to be
determined:
•
0.2% proof stress value
•
Ultimate tensile stress value
•
Ductility parameters
Procedure
1.
The length and diameter of the specimen was measured using gauges.
2. It was ensured that all gauges were correctly zeroed.
3. The test pieces were assembled into grips and placed in machine.
4. Test specimen were tested until their failure.
5. Broken test specimen was removed from the machine.
6. Test specimen were reassembled and % elongation to fracture and % reduction
in area were determined using gauges.
PAGE 2
Observations
As the force was exerted by the machine, the specimens, after initial resistance, slowly
started to elongate. At the beginning all the specimen seemed to elongate and loose the
diameter evenly, but as the force increased they started to neck and eventually broke in
two pieces.
Each specimen made different sound when breaking and broke at different time.
0.1% carbon steel took the longest time to break, 0.4% carbon steel broke quicker and
1.0% carbon steel broke the quickest out of the steel samples. Aluminium alloy showed
even less resistance and needed less time to break than the 1.0% carbon steel sample.
Figure 2 shows the specimen broken after the test:
Figure 2
PAGE 3
Results
Machine generated results table 1:
Steel (% Carbon)
Diameter [mm]
Maximum Load [N]
1
0.1
4.85
7832
2
0.4
5.00
13325
3
1.0
5.03
17532
Table 1
Machine generated results table 2:
1
Sample Label
Diameter [mm]
Maximum Load [N]
Aluminium Alloy
5.05
7568
Table 2
Figure 3 shows load-extension graph of 0.1%, 0.4% and 1.0% Plain Carbon Steel:
Figure 3
PAGE 4
Figure 4 shows load-extension graph of aluminum alloy.
Figure 4
Figure 5 shows proof load construct graphs of aluminium alloy:
Figure 5
PAGE 5
Calculations
YIELD STRESS CALCULATIONS OF STEEL SAMPLES
0.1% carbon steel
Force at yield [N]
Original crosssectional area of
the sample = (π/4)
×Ø2
[mm2]
Yield stress =
Force / Area
0.4% carbon steel
1.0% carbon steel
6486.48
7972.965
10135.125
18.4651625
19.625
19.8612065
6486.48 / 18.4651625 =
351.2820
7972.965 / 19.625 =
406.2657
10135.125 / 19.8612065
= 510.2975
[N/ mm2]
ULTIMATE TENSILE STRESS OF STEEL SAMPLES CALCULATIONS
0.1% carbon steel
0.4% carbon steel
1.0% carbon steel
7832
13325
17532
18.4651625
19.625
19.8612065
424.1500
678.9809
882.7258
Force at U [N]
Cross sectional area
[mm2]
Ultimate tensile
stress = Force at U /
Area
[N / mm2]
PAGE 6
ALUMINIUM SAMPLE: 0.2% PROOF STRESS VALUE CALCULATION
Gauge length of the
aluminium sample
25.25mm
Cross-sectional area of
the aluminium sample
Ø = 5.05
Area = (3.14/4) x 5.052
Area = 20.0194625 mm2
0.2% of the gauge length
(25.25 x 0.2): 100 = 0.0505mm
Offset distance
calculation
35mm of the x axis represents 0.25mm extension.
Offset:
(0.0505 x 35): 0.25 = 7.07 mm
Proof force
Measurement of y-axis:
120mm = 7000N
(1 x 7000): 120 = 58.3333
1 mm represents 58.3333N.
Proof force calculation:
123.5 x 58.3333 = 7204.16255N
Proof stress = proof force
/ cross-sectional areal
7204.16255N : 20.0194625 mm2 = 359.8579 N/mm2
ULTIMATE TENSILE STRESS OF THE ALUMINIUM SPECIMEN CALCULATION:
Maximum Load [N]
7568
Diameter [mm]
5.05
Cross sectional area [mm2]
20.0194625
Ultimate tensile stress [N/mm2]
7568 : 20.0194625 ≈ 378.0321N/mm2
PAGE 7
Figure 6 shows proof load graph with 0.2% proof stress value:
Figure 6
PAGE 8
Table 3: Result summary table:
Yield stress value
[N/ mm2]
0.1%
carbon
steel
0.4%
carbon
steel
1.0%
carbon
steel
351.2820
406.2657
510.2975
0.2% proof stress
value
Aluminium
alloy
359.8579
Stress
[N/mm2]
Ultimate tensile
stress value [N /
mm2]
424.1500
678.9809
882.7258
378.0321
Increase in length
of the specimen
after tensile test
35%
25%
21%
16%
Reduction in
diameter at the
point of fracture
57%
50%
30%
40%
Ductility
Table 3
PAGE 9
Discussion
Looking at the force-extension graph that was plotted after the tensile test of 0.1%, 0.4%
and 1.0% plain carbon steel (fig.3) we can see clearly that carbon content affects
mechanical properties of steel.
STRENGTH
With increasing carbon content, strength of the steel samples increased and the sample
could withstand greater load before it broke (fig.7)
HARDNESS
With increasing carbon content, greater load was necessary to cause plastic deformation,
and this means greater resistance to permanent deformation (fig.7)
For example, 380 N/mm2 would be sufficient to permanently distort mild steel sample,
while medium and high carbon steel under exactly the same force would manage to make
full recovery, if the load was removed.
882.7258
678.9809
510.2975
424.15
351.282
0.1% CARBON STEEL
406.2657
0.4% CARBON STEEL
Ultimate tensile stress value [N/mm²]
1.0% CARBON STEEL
Yield stress value [N/mm²]
Figure 7
PAGE 10
DUCTILITY
Also, the greater carbon content, the smaller plastic deformation occurred before the
sample broke. We can see that as carbon content increases, steel became less ductile
(fig.8)
57%
50%
35%
30%
25%
21%
LOW CARBON STEEL
MIDIUM CARBON STEEL
HIGH CARBON STEEL
Increase in length of the specimen after tensile test
Reduction in diameter of the specimen after tensile test
Figure 8
TOUGHNESS
Looking at the area under the load-extension curve (fig.3), we can estimate that the
smaller carbon content, the greater toughness.
The findings of this lab report do not seem to be different than published results.
For example, Cather et al. (2001, p.205) Says that low carbon steels “have moderate
strength”, medium carbon steels “have greater strength and hardness but less ductility”,
PAGE 11
while high carbon steels have “the highest strength and hardness but the least ductility
and toughness of the three groups”.
The same was noted by Burdeking and Thackray (2012, p.307), who wrote “The addition of
small amounts of carbon to iron increases the strength but reduce the ductility”.
Mechanical properties of materials determine their use. Carther et al. (2001) notice that
low carbon steel is good for use in bridges and buildings, medium is good for making rails,
were greater resistance to wear is required, while high carbon steel is used for example to
make cutting tools.
Seward (2014, p.32) points out that low carbon steel is the most common type of style used
in structures and is “very widely used in structural frames”
Lyons (2010) give an example of the Wembley Stadium and comment that weldable
structural steels “have a carbon content within the range 0.16-0.25%”.
Gordon (1991), explaining Newton’s third law of motion, say that in order to withstand a
force, the material has to balance it by exerting equal and opposite force.
STEEL AND ALUMINIUM COMPARISON
Comparing the steel samples to the aluminium sample, we can see that aluminium had
smaller loadbearing ability even than the mild steel sample (relevant parts of table 3 are
repeated here for Reader’s convenience):
alloy
0.1%
carbon
steel
0.4%
carbon
steel
1.0%
carbon
steel
378.0321
424.1500
678.9809
882.7258
Aluminium
Sample
Ultimate tensile
stress value [N /
mm2]
PAGE 12
However, aluminium showed nearly the same resistance to plastic deformation as mild
steel. Both samples required approximately the same force to be applied in order to cause
plastic deformation:
Aluminium
alloy
Yield stress value [N/
mm2]
0.1% carbon
steel
0.4% carbon
steel
1.0% carbon
steel
351.2820
406.2657
510.2975
0.2% proof stress value
359.8579
[N/mm2]
In the result, aluminium sample broke very soon after reaching the yield stress value,
requiring only 18.1742 N more to fracture, while mild steel could withstand over 72 N
before it fractured. The same is true for the other two samples of steel: in comparison to
aluminium, they also could withstand much more force after reaching the yield stress
point and before breaking.
Ductility assessment of aluminium alloy and comparing it to steel samples gave
interesting results. Although high steel sample showed over 1.4 times bigger load-bearing
ability than aluminium sample, increase in length of the two samples was not as different
as the difference in strength:
Sample
Increase in length of
the specimen after
tensile test
0.1% carbon
steel
0.4% carbon
steel
1.0% carbon
steel
Aluminium
35%
25%
21%
16%
alloy
PAGE 13
Although aluminium sample did not elongate much, it lost a lot (40%) in diameter: more
than high steel, but less than medium and mild steel.
Sample
0.1% carbon
steel
0.4% carbon
steel
1.0% carbon
steel
Aluminium
alloy
Reduction in diameter
at the point of fracture
57%
50%
30%
40%
It does not come as a surprise that Carther et al. (2001) points out low tensile strength of
and high ductility of aluminium. Lyons (2010, p.186) says that Young’s modulus of
elasticity of aluminium is “only one third that of steel”.
Lyons (2010, p.188) gives the following examples of application of aluminium in
construction: roofing, cladding, curtain-wall and structural glazing systems, flashings,
rainwater goods, vapour barriers etc.
PAGE 14
LIST OF REFERENCES:
Biggs, W. D. (1993). Properties of steel. In: Blanc, A., McEvoy, M. and Plan, R. (eds)
Architecture and Construction in Steel. London: E & FN Spon
Burdekin, M. and Thackray, R. (2012). Applied metallurgy of steel. In: Davison, B. and
Owens, W. (eds.) Steel Designers’ Manual. 7th ed. London: Wiley-Blackwell.
Cambridge University Engineering Department (2003). Data Book. Available at:
http://wwwmdp.eng.cam.ac.uk/web/library/enginfo/cueddatabooks/materials.pdf
[Accessed: 07/12/2017].
Cather, H., Morris, R. D., Philip, M. and Rose, C. (2001). Design Engineering. Oxford:
ButterworthHeinemann.
Gordon, J. (1991). The new science of strong materials, or, Why you don’t fall through the
floor. London: Penguin.
Lyons, A. (2010) Materials for Architects and Builders. 4th ed. Oxford: Elsevier.
Seward, D. (2014) Understanding Structures. Analysis, Materials, Design. 5th ed. Basingstoke:
Palgrave Macmillan.
Vernon, J. (1992) Testing of Materials. Basingstoke: Macmillan.
PHOTOGRAPHS
Title page: Htmlland (2010). Wembley Stadium arch close-up. Available at:
https://commons.wikimedia.org/w/index.php?curid=10544834
Figure 1-2: Widera, R. (2017). Steel and aluminium specimens. Author’s private collection.
PAGE 15
View publication stats