CONSTITUTIVE MODELING OF PROPORTIONAL/NONPROPORTIONAL CYCLIC PLASTICITY FOR TYPE 316 STAINLESS STEEL APPLICABLE TO A WIDE TEMPERATURE RANGE

A constitutive model of cyclic plasticity is formulated to describe proportional and nonproportional hardening of type 316 stainless steel in the range from room temperature to 973K. For this purpose, we first examine the evolution of the size of isotropic and kinematic hardening range based on the experimental results performed previously by the present authors. It is elucidated that the complicated behavior of cyclic hardening under proportional cycles is induced by the evolution of kinematic hardening variable. Then, new evolution equations of kinematic hardening variables are established by incorporating this information into the nonlinear kinematic hardening rule. In particular, the dependence of cyclic hardening on the history of strain amplitude is taken into account. The final model is established by incorporating these evolution equations into the nonproportional viscoplastic model proposed by one of the present authors. It is elucidated that the proposed model can describe the behavior of proportional and nonproportional cyclic hardening under various loading conditions including strain cycles with amplitude variation in the range from room temperature to 973K.