In situ austenite–martensite interface mobility study during annealing

A 1C3Mn1.5Si steel was partially transformed into martensite by quenching to room temperature after full austenitisation. A partitioning treatment was applied in situ in a high resolution transmission electron microscope. The width of an austenite grain in between martensite constituents was followed as a function of the annealing time. Migration of the martensite–austenite interfaces was quantitatively measured and compared with results from a model for carbon partitioning from martensite to austenite involving interface motion. The kinetics of the observed movement suggests that the interface has a semi-coherent nature. This work shows that grain boundary mobility of the martensite–austenite interfaces during annealing may play an important role in the microstructure development during the process of Quenching and Partitioning in steels