Thermally-activated hardening recovery in viscoplastic materials with kinematic hardening at high temperatures

In this work, a new constitutive model is proposed to describe the thermally-activated hardening recovery mechanism in metallic materials. This model takes up the concept of hardening recovery variable, which is extended to the case of kinematic hardening within a thermo-viscoplastic formulation including high temperature dependencies for both elastic and viscoplastic properties. The model is identified for AISI 316L austenitic stainless steel using experimental data from uni-axial tests conducted over a wide range of temperature (from room temperature to 1273 K) and at two different strain rates (2.5 x 10-4 and 2.5 x 10-3 s-1). Validation is further achieved with rather good agreements by comparing the simulated responses with additional experimental data where the material is subjected to complex thermomechanical loading paths while other examples are presented to provide a better insight of the model and to illustrate its predictive capabilities.