Experiments to Determine Small Offset Yield Surfaces for 304L Stainless Steel under Combined Tension and Torsion

摘要

The highly strain-hardening nature of 304L stainless steel, coupled with hardening due to a stress-induced martensitic transformation, caused considerable difficulty in determination of yield curves by a multiple-probe small-offset technique. Small probes of added shearing stress appeared to cause considerably more accumulated strain-hardening damage to a yield curve than small probes of added tensile stress. When a portion of a yield curve could be defined it appeared to be convex, and the plastic strain increment vector was normal in agreement with the stability postulate. Some evidence to support corner formation on a yield curve due to the disturbance of probing is presented. The exact nature of corners is indeterminant. An extreme Bauschinger effect for surprisingly small prestrains was observed in both tension and torsion. (Author)