Microstructural analysis of martensite constituents in quenching and partitioning steels

•An approach to distinguish “old” from “new” martensite in Q&P steels is presented•Methodology allows separate characterization of microstructure and crystallography “Old” martensite has larger block size and more perfect lattice than the “new” one•The differences between the old and new martensite depend on their carbon contents

A methodology to distinguish martensite formed in the first quench (M1) from martensite formed in the second quench (M2) of the Quenching and Partitioning process is presented, enabling the study of the structural characteristics of both microstructural constituents. Investigations show that M1 displays larger block size and less lattice imperfections than M2, differences that can be related to their respective carbon contents.