Dilatometric study of reaustenitisation of high silicon bainitic steels:: Decomposition of retained austenite

The formation of austenite during the heating of high-silicon steels with a microstructure of bainitic ferrite plates separated by carbonen-riched regions of retained austenite has been studied. As the steel is heated, retained austenite decomposes into a mixture of ferrite and carbides before a temperature is reached where it becomes the more stable phase and hence can grow. The decomposition makes it necessary for the austenite to nucleate from the mixture of ferrite and carbides. In this work, dilatometric analysis, transmission electron microscopy and X-ray diffraction have helped to identify the processes that take place during the heating experiment.