Control of Austenite in TRIP-assisted steels using Isothermal and Non-Isothermal Treatment

Abstract

Mechanical stability of austenite in TRIP-assisted steels is known to be affected by chemical composition as well as morphology and sizes. Properly stabilized austenite provides persistent work-hardening during deformation delaying the occurrence of local necking and ensures excellent mechanical balance – integration of tensile strength and tensile strain. To improve the strength and elongation, increasing carbon content is typical practice

however, the presence of coarse retained austenite grains often make a problem due to a loss of mechanical stability. In this work, two-step heat treatment and non-isothermal heat treatment were employed to TRIP-assisted steel to deal with this issue. It was revealed that both two-step heat treatment and non-isothermal treatment are noticeably promising in securing mechanical stability of retained austenite. In fact, the methods not only refine coarse grains but also improve the carbon concentration of retained austenite. Hence, they give better mechanical performance compared to the conventional processing route.