Question 1 Engineering stress-strain data from a tensile test on a cylindrical rod of AISI 4140 steel tempered at 649 °C

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Question 1 Engineering Stress Strain Data From A Tensile Test On A Cylindrical Rod Of Aisi 4140 Steel Tempered At 649 C 1 (70.28 KiB) Viewed 34 times

Question 1 Engineering stress-strain data from a tensile test on a cylindrical rod of AISI 4140 steel tempered at 649 °C are listed in Table Q1 below. The diameter of the circular section before testing was 10 mm for this specimen, and after fracture the minimum diameter in the necked region was 6 mm. Table Q1: Tensile test data of tempered AISI 4140 σ, MPa E, % σ, MPa E, % 0 0.00 897 4.51 403 0.20 932 8.07 587 0.28 899 12.04 836 0.42 831 15.03 846 0.63 689 18.52 829 0.98 574* 20.35* 828 1.99 ("The last point is fracture) (a) Plot the stress-strain curve and label the regions of elastic, yielding, strain hardening and necking regions in the graph. (b) Calculate the true strain and stress at engineering strain levels of 0.0042 and 0.1. Does the material undergo stable or unstable plastic deformation at a strain of 0.1? (c) Determine the elastic modulus, 0.2% offset yield strength, ultimate tensile strength, strain hardening ratio, percent elongation, and percent reduction in the cross- sectional area of the fractured rod. (d) AISI 4140 steel has a Poisson's ratio of 0.27. At a strain of 0.28% in this experiment, what is the change in the radius of the specimen?