Microstructural evolution of as-cast 42CrMo ring during hot rolling

In order to avoid traditional ring parts hot rolling process problems of many times heating and so on, the as-cast 42CrMo alloy ring short process flow blank-casting and rolling compound forming process is taken as the research object, a series of experiments are performed on the Gleeble-1500D machine and metallographic microscope, the flow stress curves under temperatures of 850-1 150°C and strain rates of 0.05-5 s-1 are obtained. The dislocation density variation and the grain growth kinetics of each dynamically recrystallizing grain are calculated by transforming the flow stress curves. In addition, the nucleation and the growth kinetics of dynamically recrystallized grains are evaluated. The grain topology deformation technology is studied, and the grain topology structures are optimized by use of the principal component analysis. The results show that the Kock-Mecking (KM) dislocation density equation can be employed to calculate the dislocation evolution during dynamic recrystallisation of 42CrMo alloy. The KM dislocation density model coupled with cellular automata method and optimized grain topology transformation technology can simulate dislocation density during dynamic recrystallization process accurately. © 2014 Journal of Mechanical Engineering.