tensile testing and hardness testing of various...
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Tensile Testing and Hardness Testing of Various Metals Technical Report Submitted to: Dept. of Industrial & Manufacturing Engineering
Prof. Edward C. De Meter 310 Leonhard Building
The Pennsylvania State UNiversity University Park, PA 16802
Submitted by: Team: 4
Pavel Shusharin, Erik Venuti
Matthew Prevost David Hontz
Date: 2/10/16
Table of Contents Methodology Analysis
Analysis of data obtained with an extensometer Analysis of true stressstrain for ductile materials
Investigation Methodology The metals that were tested in the lab: Cold Rolled Annealed Steel 6061 Aluminum 1018 Hot Rolled Brass Cast Iron Our group tested: Cold Rolled Annealed Steel The measurements that were taken:
1) Tensile Test a) Time b) Position c) Force d) Change in length
2) Rockwell Hardness 3) Brinell Hardness 4) PreTensile Test measurements
a) Gage Width b) Gage Thickness c) Gage Length
5) PostTensile Data a) Gage Width b) Gage Thickness c) Permanent Length Between Jaw Alignment Marks
The Mechanical properties that were derived:
1) Young’s Modulus 2) Engineering and True Strain at Yield point 3) Ultimate Tensile Stress 4) Engineering and True Strain at UTS 5) Ductility 6) Engineering and True Shear Strain 7) True Strain at Fracture 8) Measured and Predicted Max True Stress 9) Strain Hardening exponent 10) Strength Coefficient 11) Predicted toughness
Analysis of data obtained with an extensometer. For each metal:
● Engineering stressstrain plot with a figure caption ● Additional graph that shows a 0.2% offset and includes a trend for the linear
portion of the graph ● Table with e0 , eu , E, y (shear strain), UTS and ductility.
Brass
Figure 1.1 Engineering stressstrain plot for Brass
● The shape of this plot indicates this Brass is a ductile metal ● It does not appear the extensometer slipped during this tensile test
Figure 1.2 Engineering stressstrain plot of the elastic region with 0.2% offset Table 1.1 Table of mechanical properties of Brass
e0 (in/in) eu (in/in) E (ksi) y (ksi) UTS (ksi) Ductility (%)
0.0044 0.2058 16042 38.0 47.9 35
6061 Aluminum
Figure 1.3: Engineering Stress vs. Strain plot for Aluminum Specimen Ductility: 6061 Aluminum exhibits a large region of plastic deformation before fracture which is indicative of ductility.
Figure 1.4: Zoomed Engineering Stress vs. Strain displaying 0.2% offset for Aluminum Specimen. Extensometer: The data contains a slight discontinuity at the beginning of the test which indicates that the extensometer slipped. Table 1.2 Mechanical properties of 6061 Aluminum
ϵo (in./in.) ϵu (in./in.) E (ksi) γ (ksi) σUTS (ksi) Ductility
0.00537 0.0903 8605.9 35.417 41.544 16%
1018 Hot Rolled Steel
Figure 1.5 Engineering Stress vs Strain plot for 1018 Hot Rolled Steel
Figure 1.6 Zoomed Engineering Stress vs Strain plot of 1018 Hot Rolled Steel displaying 0.2% offset Comments: Based on this data, the 1018 Hot Rolled Steel specimen exhibits significant ductility due to its large plastic deformation. The data shows a slight discontinuity at the beginning of the test, indicating that the extensometer slips for a brief moment. Table 1.3 Mechanical properties of 1018 Hot Rolled Steel
e0 (in/in) eu (in/in) E (ksi) y (ksi) UTS (ksi) Ductility
.0035 .01912 33.141*10^6 51.63 60.89 33.0%
Cast Iron
Figure 1.7: Engineering Stress vs. Strain for Cast Iron Specimen Ductility: The data shows almost no signs of plastic deformation which indicates that Cast Iron is not ductile.
Table 1.4 Mechanical Properties of Cast Iron
ϵo (in./in.) ϵu (in./in.) E (ksi) γ (ksi) σUTS (ksi) Ductility
N/A N/A 15118 N/A 6.8087 0.5%
1018 Annealed Steel
Figure 1.8: Engineering Stress vs. Strain for the 1018 Cold Rolled Steel
Figure 1.9: Zoomed Engineering Stress vs. Strain displaying the 0.2% offset and elastic region. Comment: Based on this data, the 1018 Cold Rolled Steel specimen exhibits significant ductility due to its large plastic deformation. The data is very smooth and does not exhibit any discontinuities indicating that the extensometer did not slip during testing.
Table 1.5 Mechanical properties of 1018 Annealed Steel
ϵo (in./in.) ϵu (in./in.) E (ksi) γ (ksi) σUTS (ksi) Ductility %
0.003373 0.2219 24128 31.84 44.46 42
Analysis of true stressstrain for ductile materials For each ductile metal:
● True stressstrain plot ● A table with yt, mstmax (measured maximum true strain), k, n, pstmax (predicted
maximum true strain) and predicted toughness.
Brass
Figure 2.1 A true stressstrain plot, including a flow stress equation and trendline
For this metal, the predicted value for maximum true strength was reasonably close to the actual value. This measurement has an 18.6% error, which is slightly than the other metals tested.
Table 2.1. Mechanical properties evaluated from true stressstrain plot
yt (ksi) mstmax (ksi) k n pstmax predicted toughness (in/in)
38.4 78.72 68.52 0.122 64.05 32.7
e0 0.00442 in/in
eu 0.20577 in/in
E 16032 ksi
γ 38.0 ksi
UTS 47.9 ksi
Ductility 35 %
ef 0.57549 in/in
σtmax 78.718 ksi
κ 68.52 ksi
η 0.1222
Toughness 32.70 lb/(in/in)3
Aluminum
Figure 2.2. True Stress vs. Strain plot for Aluminum Specimen Table 2.2 Mechanical properties evaluated from true stress vs. strain plot
γt (ksi) κ (ksi) η
measured σtmax (ksi)
predicted σtmax(ksi)
predicted toughness (lb*in./in.^3)
35.607 56.176 0.0941 52.605 46.944 3.542141
Comments:
1018 Hot Rolled Steel
Figure 2.3. True Stress vs Strain plot for 1018 Hot Rolled Steel.
The first (blue) data set represents strain data from 0 to ε0 . The second (red)
data set represents strain data from ε0 to εu. The third data set (green) represents the predicted failure point corresponding to εf and σt max. Table 2.3. Mechanical properties evaluated from true stress vs. strain plot
yt (ksi)
κ (ksi) η εf(in/in) σt max Predicted (ksi)
σt max Flow Stress (ksi)
Toughness (lbf*in/in^3)
51.87 72.31 .064 .0863 61.83 65.58 4.848
The value for predicted σt max was very close to the actual value obtained with the data, varying by only 3.75 ksi and yielding a mere 5.7% error.
1018 Cold Rolled Steel
Figure 2.4. True Stress vs. Strain for the 1018 Cold Rolled Specimen
The value for predicted σt max was much less than the actual value obtained with the data. This is because the measured value takes into account the instantaneous crosssectional area, while the predicted value uses the original cross sectional area. The values vary much more for the annealed steel than the other materials because of the annealed steel’s high ductility. Table 2.4. Mechanical properties evaluated from true stress vs. strain plot
yt (ksi) κ (ksi) η εf(in/in) σt max Predicted (ksi)
σt max Flow Stress (ksi)
31.95 72.479 0.2016 .3506 58.6741 81.3956
Analysis of data obtained with an extensometer. Cold Rolled Annealed steel
Figure 1.3 Engineering StressStrain plot for Cold Rolled Annealed Steel
Figure 1.4 Engineering Stress Strain plot of the elastic region with 0.2% offset
e0 (in/in) eu (in/in) E (ksi) y (ksi) UTS (ksi) Ductility
0.039 0.1784 1011.2 38.36 70.02 22.16 %
Based on the data for the five specimens, the material that would be the easiest to form into a shape would be 1018 Annealed Steel. It exhibited the highest ductility percentage (42%) and a relatively low yield strength (31.84 ksi). These properties make it easy to plastically deform and form into a shape. For similar reasons, the Cast Iron sample would be the most difficult material to plastically deform and form into a shape. It exhibited a very low ductility percentage (0.5%) making it very difficult to plastically deform. Annealing is a process of heat treating a metal in a certain way that would improve its material properties. Mainly, annealing will increase ductility while decreasing hardness. These changes increase the formability of the annealed metal and it more workable. This is consistent with our data because of the two samples of 1018 Steel (hot rolled and annealed), the annealed specimen exhibited a higher ductility percentage by 9 percent. Steel specimens have alloying elements present in their structure, meaning an increased dislocation density. The increase in number of dislocations causes the steels to yield in a twopart fashion, resulting in an upper yield strength and lower yield strength. The anomaly is primarily found in steels due to the high number of interstitial defects that the alloying process results in.
Hardness values for tested specimens Table . Hardness values for annealed hot rolled steel.
Annealed hot rolled Steel
Rockwell B Test Brinell 10/500 Hardness Test
Average 51.85 81.25
Conversion table value 52 85
Table . Hardness values for cold rolled annealed steel.
Cold rolled annealed steel
Rockwell B Test Brinell 10/500 Hardness Test
Average 99.7 227.5
Conversion table value 95 220
Table . Hardness values for aluminum.
6061 Aluminum Rockwell B Test Brinell 10/500 Hardness Test
Average 53.825 95.6
Conversion table value 54 87
Table . Hardness values for brass.
Brass Rockwell B Test Brinell 10/500 Hardness Test
Average 71.1 110.5
Conversion table value 71 112
Table . Hardness values for cast iron.
Cast Iron Rockwell B Test Brinell 10/500 Hardness test
Average 96.1 201.5
Conversion 97 184
Table . Hardness values for hot rolled steel.
Hot Rolled Steel Rockwell B Test Brinell 10/500 Hardness Test
Average 83.7 137.5
Conversion table value 84 140
Comments on the agreement of the average hardness values measured to that of the conversion tables: All the measurements closely correlated to the values given in the conversion tables of ASMI. Even though there is some deviation it is negligible considering all the components that went into testing, from slight deviations of the internal structure of materials, to human error. Tables. The info is taken from the International ASTM standard:
http://www.mdmstandard.ro/download/resurse/Tabele%20de%20conversie%20ASTM%20pentru%2
0duritati%20(in%20engleza).pdf