The interfacial damage of the deformation heterogeneity in the transformation-induced plasticity (TRIP)-assisted duplex stainless steel

Abstract

The characteristic of differences in material properties between phases gives rise to significant deformation heterogeneity in dual-phase or multi-phase materials, consequently resulting in complex damage laws. In this study, the microcracks characteristics of transformation-induced plasticity (TRIP)-assisted duplex stainless steel were observed after large deformation (engineering strain up to 55%). It has been determined that microcracks invariably occur at interface locations, including the phase boundary between original austenite and ferrite, the grain boundary of original austenite, and the grain boundary of ferrite. The deformation heterogeneity of various types of interfaces is analyzed by using crystal plasticity finite element method (CPFEM). Deformation degree coordination parameter $k_l$ and slip transfer parameter $k_{tf}$ are established, based on the velocity gradient tensor $L_p$ and the slipping rate $\dot{\gamma }$ of activated slip system in CPFEM, to analyze the multi-slip heterogeneous deformation behavior of grains on both sides of the interface. A novel interfacial damage model considering the slip transfer parameter $k_{tf}$ is established, which reveals the correlation between deformation heterogeneity and damage mechanism, to provide a criterion for various types of interfacial failure behaviors. The interfacial damage model based on deformation heterogeneity can stand as an invaluable instrument for exploring the damage behaviors of two-phase or multi-phase materials.