Effect of Ti on Austenite Grain Growth Behavior in Medium Carbon Manganese Steel

Effect of Ti on austenite grain growth behavior in medium carbon manganese steel at different heating temperature and time were studied.The results show that Ti-bearing steel exhibited a much sluggish growth rate of austenite grain compared with Ti-free counterpart at higher heating temperature,which was attributed to the pinning effect of Ti(C,N) nanoparticles within size of 100 nm on austenite grain boundaries.The complete solid solution temperature was 1 450℃ calculated by Thermo-calc,and the amounts of nanoparticles Ti(C,N) were still large even at higher temperature.The austenite grain growth model of Ti-bearing steel was successfully established,ie.$D_B=729.25 t^{0.16} \exp \left(-\frac{71 972.3}{R T}\right)$,figuring the larger activation energy for migration of austenite grain boundary and the smaller grain growth index n,which were 72 kJ/mol and 0.16 respectively.The results predicted by the modified equation are found to be good agreement with the experimental results.The developed model could be employed to predict accurately the austenite grain growth of Ti-bearing medium carbon manganese steel.