Effect of prior austenite grain size on bainitic transformation above and below Ms in medium Mn steel

Abstract

The effect of prior austenite grain (PAG) size on bainitic transformation kinetics below Ms in 0.2C-3.92Mn-1.6Si steel has been investigated using a dilatometer. The samples were austenitized at two different temperature to achieve the average PAG size of ~10.9 μm and ~17.3 μm. The results show that above Ms the austenite grain size plays a significant role in bainitic transformation kinetics. However, the influence of austenite grain size on bainitic transformation kinetics below Ms becomes weaker which is ascribed to the acceleration of prior martensite on bainitic transformation below Ms.