Influence of Strain History and Cooling Rate on the Austenite Decomposition Behavior and Phase Transformation Products in a Microalloyed Steel

The effect of simple strain path changes as well as post-deformation continuous cooling rate during thermomechanical-controlled processing of microalloyed steel was studied using laboratory physical simulation. The phase transformation characteristics were directly analyzed by dilatometry under various cooling rates. The microstructures of the transformation products were characterized quantitatively using EBSD. The results have shown that while strain path changes impose a considerable influence on the hot flow behavior of the austenite, the cooling rate following hot deformation is the determining factor of the phase transformation mechanism and behavior which establishes the final transformation products and subsequent mechanical properties.