Real-Time In Situ Neutron Diffraction Investigation of Phase-Specific Load Sharing in a Cold-Rolled TRIP Sheet Steel

Abstract

Real-time in situ neutron diffraction was used to investigate the loading-direction dependence of phase-specific load sharing in a cold-rolled TRIP 780 sheet steel under tension at room temperature. A slightly lower yield stress and relatively faster initial strain hardening were observed for the tension along the rolling direction (RD) than those along the transverse direction (TD) and the diagonal direction (DD). In all three loading directions, the redistribution of inter-phase and inter-granular load sharing occurs upon the yields of the body centered cubic (BCC) matrix and the face centered cubic (FCC) phase. The FCC phase is found to yield earlier along the RD than those along the TD and DD. The quantitative evolution of phase-specific stress indicates a rapid strain hardening in the FCC phase after yielding during the RD tension. Possible mechanisms of the direction-dependent phase-specific load sharing are discussed in association with the different initial textures in the RD, DD and TD.