Ultra-fine austenite grain steel produced by thermomechanical processing

We have tried to make fine austenite grains by applying thermomechanical processing to steel with C, Mn and Mo. The thermomechanical processing consists of tempering and subsequent cold rolling of martensite, followed by austenitization. The stabilization of the substructure of tempered martensite and acceleration of the nucleation of austenite lead to the refinement of austenite grains. These are due to alloying with Mn and Mo. We can produce fine austenite grains, 0.9μm in diameter, by applying the thermomechanical processing to steel with 0.4% C, 3% Mn and 1% Mo.