Influence of Intercritical Heating on the Microstructure and Mechanical Properties of Al‐Rich Quenching–Partitioning–Tempering Steel

Abstract

The microstructure and mechanical properties with traditional and intercritical heating and quenching–partitioning–tempering (referred as Q–P–T and I&Q–P–T, respectively) treatment for the Al‐rich steel are revealed through optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), electron probe microanalysis (EPMA), and tensile testing. Results indicate that the multiphase microstructures of the Q–P–T and I&Q–P–T‐treated steel consist of martensite (M), ferrite (F), and retained austenite (RA). Meanwhile, the I&Q–P–T‐treated steel has much more ferrite and relatively less RA than those of the Q–P–T‐treated one. During tensile testing, more RA with optimized stability transforms to martensite in the I&Q–P–T‐treated specimen, which leads to a more pronounced transformation‐induced plasticity (TRIP) effect. Thus, with more ferrite and a remarkable TRIP effect, the elongation and product of strength–elongation of the I&Q–P–T steel are higher than those of the Q–P–T‐treated one.