On the extent of transformation of austenite to bainitic ferrite and carbide during austempering of high Si steel for prolonged duration and its effect on mechanical properties

In this work, the effect of holding durations (10-60min) during austempering at 300, 350 and 400 degrees C on the structure and properties of a 0.61C-1.71Si-0.86Mn steel has been studied. At all the austempering temperatures, austenite fraction gradually decreases with the increase in holding duration. Austempering temperature has been found to influence the rate of depletion of austenite. The effect of Mn and Si content of steel on the extent of transformation of austenite to bainitic ferrite and carbides during prolonged austempering holding has also been looked at. Analysis drawn from existing literature along with the current data shows that along with Si, Mn also plays an important role in controlling the rate of transformation of austenite to bainitic ferrite and carbide.