Plasticity modeling for a metastable austenitic stainless steel with strain-induced martensitic transformation under cyclic loading conditions

In the present paper, the strain-induced martensitic transformation and the cyclic plasticity model of a metastable austenitic steel AISI 348 under multi-axial cyclic loadings were studied. Cyclic loading tests under different stress triaxialities and strain amplitudes were carried out and used to verify the material model. Based on the Santacreu model, a kinetics model for evolution of martensitic transformation under multi-axial cyclic loading conditions was obtained by defining a threshold of equivalent plastic strain for phase transformation. The model can degenerate into a simplified form to describe strain-induced martensite evolution under monotonic loadings. The prediction of martensite content by the model matched well with experiments. By correlating the effect of martensitic transformation into isotropic hardening, a modified Ohno-Wang model was obtained and verified. The stress-strain response along the different loading paths and histories was well described by the introduced model.