Stress-strain data are plotted in Fig. P4.5 for the initial portion of a tension test on AISI 4140 steel tempered at 538?C (1000?F). Note that data points A and B are labeled with their stress-strain coordinates.
(a) Determine the elastic modulus E.
(b) If a bar of this material 100 mm long is strained to point A and then unloaded, what is its length at point A and also after unloading?
(c) If a sample of this material is strained to point B and then unloaded, what is the plastic (permanent) strain that remains after unloading?
(d) Repeat (b) where the bar is instead loaded to point B and then unloaded.
