Retained austenite in Q&P steel for automobile

Retained austenite of QP(Quenching and Partitioning) processed 0.2C-1.51Si-1.84Mn steel heated in dual-phase region and full austenite region were investigated.The results show that the maximum volume fraction of retained austenite is 13.39% when heated in dual-phase region and 5.23% in austenite region.Carbon partitioning completed within 10 s for both heating modes.There are two forms of existence of retained austenite in dual-phase region,the film between lath martensites and the bulk located in original austenite grain boundaries.Retained austenite heated in full austenite region can be acquired in the shape of films distributed within lath martensite.The distribution of retained austenite is related to the mount of grain boundaries by electron backscattered diffraction method.