Influence of Parameters of Quenching and Partitioning Process on Microstructure and Fraction of Retained Austenite

Certain amount of retained austenite can increase ductility of steels because of the TRIP phenomenon during plastic deformation. One method for achieving this is partitioning of carbon into austenite to stabilize it at room temperature. The quenching and partitioning (Q&P) heat treatment leads to a microstructure consisting of martensite and stabilized retained austenite between martensite plates، which provides a better combination of strength and ductility. In this study، the effect of parameters of Q&P process (quenching temperature، partitioning temperature and partitioning time) on the microstructure and retained austenite volume fraction of a low alloy medium carbon steel was investigated. The results showed that the high increase in partitioning time causes the disappearance of martensite blades and reduction of austenite volume fraction. However، increasing of partitioning temperature made the retained austenite films become thicker and its volume fraction increase. On the other hand، by increasing the quenching temperature، carbon content of retained austenite increased sharply.