Describe the material properties that have an effect on the relative position of the curves
shown in Fig. 7.19. Observing curves (a) and (c) in Fig. 7.19 on p. 364, note that the former is annealed and the latter is heat treated. Since these are all aluminum alloys and, thus, have the same elastic modulus, the difference in their springback is directly attributable to the difference in their yield stress. Likewise, comparing curves (b), (d), and (e), note that they are all stainless steels and, thus, have basically the same elastic modulus. However, as the amount of cold
work increases (from annealed to half-hard condition), the yield stress increases significantly
because austenitic stainless steels have a high n value (see Table 2.3 on p. 37). Note that these
comparisons are based on the same R/T ratio.