Characterisation on Al-bearing hot-rolled TRIP steel produced through isothermal bainite transformation

Abstract

In this study, an energy-efficient processing route involving hot rolling and on-line heat treatment was proposed, which is applied to Nb-alloyed and Al-containing hot-rolled TRIP steel. The experiments were carried out involving hot rolling and on-line heat treatment, where the samples were subjected to different bainite hold times. The results shows that during isothermal bainite transformation, film-like and blocky retained austenite were present in microstructures at bainite hold times of 10 and 20 min. The sample subjected to bainite hold time of 20 min exhibited excellent mechanical properties, with tensile strength of 839 MPa, total elongation of 38% and product of strength and elongation of 31.9 GPa%. The instantaneous work hardening exponent increased gradually with true strain at bainite hold time of 20 min.