In situ study of transformation in a superbainite steel

To investigate the dynamic process of bainite transformation, in situ observation of bainite transformation in a 0. 42% C superbainite steel was conducted on a high temperature laser scanning confocal microscope. It is found that the bainite embryos nucleate not only in parent austenite grain,on grain boundary and previously formed bainite platelet,but also at annealing twin during bainite transformation. In addition,during the process of bainite transition,pre-formed bainite plates and later-formed bainite plates grow in different directions resulting in the impingement between them. With mutual intersection of bainite plates,an interlocked bainite microstructure would be developed finally. In situ observation investigation makes it possible that bainite nucleation and growth can be identified in real time during isothermal holding,providing efficient method for transition theory analysis.