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.