Effects of Initial Austenite Grain Size on Microstructure Evolution of Medium Carbon Steel

The deformation behaviors and microstructure evolution for 9 different original austenite grain size of medium carbon steel were systematically investigated in this work by singlepass hot compression tests on Gleeble 3500 simulation test machine at deformation temperature of 650 degrees C, the strain of 0.92, the strain rate for 0.01s-1, 1 s-1, 10s-1, the austenite grain sizes have an effect on the size and the amount of ferrite. The results show that the small grain size of austenite in deformation has an easier trend of work hardening, a faster rate which expands to the austenite inner, and promotes the ferrite precipitation. The smaller deformation rate of austenite grain in same size, the smaller size of average diameter of induced ferrite; the smaller grain size of austenite, the easier the dynamic recrystallization and the easier to get fine grained lamellar spheroidized cementite.