Superior TRIP effect in a duplex stainless steel and its mechanism studied by in situ neutron diffraction experiments

This study investigated the transformation-induced plasticity (TRIP) effect in duplex stainless steel (DSS), with a focus on how the deformation temperature influences the mechanical properties of 24Cr-5Ni-0.18 N DSS. The 24Cr-5Ni-0.18 N steel exhibited an optimal balance of tensile strength (TS) and uniform elongation (U.El) at temperatures below 183 K, primarily due to the deformation-induced martensitic transformation (DIMT) of the austenite ( γ ) phase. The large improvement of U.El by the TRIP effect in 24Cr-5Ni-0.18 N with a γ volume fraction of 50% is a significant finding. The factors contributing to the excellent TRIP effect and its mechanical properties for 24Cr-5Ni-0.18 N include not only the conventional findings—the TRIP effect due to DIMT and the increase in stress and work hardening of the γ and α phases with a decrease in the deformation temperature—but also include changes in the interactions between the constituent phases and in the texture due to DIMT. DIMT reduced the effects of crystal rotation and changed the stress partitioning among the constituent phases. DIMT also weakened the texture of the α and α' phases. For JIS-SUS329J4L, the phase stress, work hardening, and KAM value increased with a decrease in temperature, but the texture became weaker.