Experimental study of internal variable evolution in SS304L, at multiple rates and temperatures

Most metals exhibit a deformation-induced uniaxial yield strength asymmetry . Interpreted within the context of macroscale viscoplastic models, it is c onventional to describe this yield strength asymmetry with an isotropic har dening variable kappa, and a kinematic hardening variable, alpha. The focus of this work was to conduct a series of reverse yield experiments to direc tly measure the evolution of alpha and kappa in 304L stainless steel (SS304 L) over large ranges of temperatures and strain rates. We found that the ma terial exhibited inelastic behavior immediately on changing, the straining direction. We discussed the ramifications of this behavior on our goal to d irectly measure alpha and kappa within the context of an isotropic/kinemati c hardening model framework. We also explored the capability of the model t o simulate the behavior of SS304L under differ ent loading conditions acros s a wide range of temperatures and strain rates.