Tensile Properties and StrengtheningMichael Muldoon, Mechanical Engineering

Materials Science Lab, Section 04

9/9/2014

Group Members: Chad Uckermark Nathan Mckerley

Abstract: In this lab a tensile test was conducted on two steel specimens and two aluminum specimens. The 6061-T6 Aluminum specimen was precipitation hardened and the 1018-T3 Steel specimen was strain hardened. This lab was done to study and observe the effects of the hardening on these materials. Before the samples were tested the length was marked and the original width length and thickness were measured. While the pieces were being tested the extensometer took data and produced stress-strain graphs, yield strength, tensile strength and elastic modulus. As expected strain hardening made the 1018-T3 Steel specimen less ductile and have higher yield and tensile strengths than the 1018-T4 sample. The precipitation hardening made the 6061-T6 Aluminum specimen less ductile than the T0 specimen and increased the tensile and yield strengths by about four times. Overall the tests returned results that were close to the accepted values for the given materials.

Tensile Properties and Strengthening

Michael Muldoon, Mechanical Engineering

Materials Science Lab, Section 04

Objective: This lab was conducted to observe and study the effects strengthening has on a materials tensile strength, yield strength and ductility.

Procedure:

Experimental Procedure:

1) Two aluminum pieces and two pieces of steel were tested.a. Four Materials

i. Red, 6061-T0 Aluminum (Solution Annealed)ii. Green, 6061-T6 Aluminum (Precipitation Hardened)

iii. Blue, 1018-T4 Steel (Skin Rolled)iv. Yellow, 1018-T3 Steel (Quarter Hard)

b. Materials are held to ASTM-A109 standard2) Experiment

a. The Instron 1125 Load Frame with MTS SinTech ReNew System was used to test the materials.

b. The specimens were tested according to ASTM-E- Tension Testing of Metallic Materials standard.

c. Once the specimens were marked and prepped they were installed in the tensile tester.

d. The test was then conducted and stretched the specimens until they broke. Data was recorded before and after the test.

Specific Test Procedure:

1) All specimens were marked in the center and approximately one inch left and right of the center.

2) This distance was measured using a dial caliper and recorded as the original length. The original width and thickness were also measured and recorded.

3) The tensile testers load sensor and extensometer were then calibrated.4) The specimen was then installed in the jaws of the tensile tester flush with the

backing plates. Then the extensometer was installed on the specimen.5) Once the specimen was installed the load sensor and extensometer were zeroed.

6) The tensile tester then began to stretch the specimen.7) Once the strain reached 5% the extensometer was removed to avoid any damage to

the equipment.8) The tensile tester continued to run until the specimen was broken.9) The specimen was then removed from the tensile tester.10) The final length was then measured with a dial caliper and recorded.11) This procedure was repeated for all four specimens.

Analysis:

Data Plots

Figure 1: (Blue Line) 1 1018-T4, (Green Line) 3 1018-T3

Stress vs. Strain Steel

Figure 2: (Red Line) 2 6061-T0, (Green Line) 4 6061-T6

Figure 3: (Blue Line) 1 1018-T4, (Green Line) 3 1018-T3

Stress vs. Strain Aluminum

Elastic Region Steel

Figure 4: (Red Line) 2 6061-T0, (Green Line) 4 6061-T6

Elastic Region Aluminum

Figure 5: Both Steel Fractures

Figure 6: Both Aluminum Fractures

6061-T6 Aluminum (Green)

6061-T0 Aluminum (Red)

1018-T3 Steel (Yellow)

1018-T4 Steel (Blue)

Results Tables

MaterialExperimental Elastic Modulus (Msi)

Accepted Elastic Modulus (Msi) % Error

Yellow 1018-T3 Steel 25.38 29.70 -14.55Blue 1018-T4 Steel 27.74 29.70 -6.60Red 6061-T0 Al Alloy 10.05 10.00 0.50Green 6061-T6 Al Alloy 9.55 10.00 -4.50

MaterialExperimental Yield Strength (ksi)

Accepted Yield Strength (ksi) % Error

Yellow 1018-T3 Steel 47.74 45.00 6.09Blue 1018-T4 Steel 32.78 30.00 9.27Red 6061-T0 Al Alloy 7.86 8.00 -1.75Green 6061-T6 Al Alloy 46.15 40.00 15.38

MaterialExperimental Tensile Strength (ksi)

Accepted Tensile Strength (ksi) % Error

Yellow 1018-T3 Steel 51.54 55.00 -6.29Blue 1018-T4 Steel 47.69 48.00 -0.65Red 6061-T0 Al Alloy 17.15 18.00 -4.72Green 6061-T6 Al Alloy 49.12 45.00 9.16

MaterialExperimental Elongation at Failure (%)

Accepted Elongation at Failure (%) % Error

Yellow 1018-T3 Steel 39.79 35.00 13.69Blue 1018-T4 Steel 39.15 35.00 11.86Red 6061-T0 Al Alloy 29.37 25.00 17.48Green 6061-T6 Al Alloy 11.91 12.00 -0.75

Observations:

Steel Specimens: The 1018-T3 steel was strain hardened and was less ductile than the 1018-T4 Steel. Being less ductile the yellow specimen (1018-T3 steel) has a much higher yield strength and a moderately greater tensile strength. Both specimens had roughly the same percent elongation. Since both specimens are made of the same steel they do have about the same elastic modulus.

Aluminum Specimens: The 6061-T6 Aluminum specimen which was precipitation hardened was significantly less ductile than the 6061-T0 Aluminum Specimen. The green (6061-T6 Aluminum) specimen has a much larger tensile strength and yield strength than the red (6061-T0 Aluminum) specimen. Since the green specimen was much less ductile its percent elongation was less than the red specimen. Both specimens have about the same elastic modulus because they are the same material.

Conclusion: The results demonstrated the effects of both strain hardening and precipitation hardening. As expected both techniques made the material less ductile and increased both yield strength and tensile strength while the elastic modulus remained constant.

References:

"ASTM Material Specification A109-13- Cold-Rolled Mild Carbon Steel Strip." N.p., 4 Feb. 2014. Web. 8 Sept. 2014.

"Online Materials Information Resource - MatWeb." Online Materials Information Resource - MatWeb. N.p., n.d. Web. 08 Sept. 2014.

Appendix:

*Data plots may not reflect this data due to malfunction of machinery during testing.