Flow Stresses of Prestrained Annealed OFHC Copper and SAE 1018 Steel

Abstract

The tensile properties of annealed OFHC copper and SAE 1018 steel drawn to various prestrains up to ln A0 /A ≅ 1.5 were evaluated. It was found that the resulting Bridgman corrected curves could not be matched at the calculated prestrains. However, a match could be achieved by ignoring the calculated or theoretical prestrains. This method of obtaining a unified curve leads to the belief that the two materials under investigation soften at the higher prestrains. For the moment there appears to be no method to predict the softening effects. It was found that the yield strengths fall below the unified true stress-true strain or flow stress curves and that necking appears to be in agreement with the theory. Consequently, necking strains in tension drop to nearly zero after the first drawing pass.