MODELING OF MICROSTRUCTURAL EVOLUTION IN MICROALLOYED STEEL DURING HOT FORGING PROCESS

The microstructural evolution of microalloyed steel during hot forging process was investigated using physical simulation experiments. The dynamic recrystallized fraction was described by modifying Avrami's equation, the parameters of which were determined by single hit compression tests. Double hit compression tests were performed to model the equation describing the static recrystallized fraction, and the obtained predicted values were in good agreement with the measured values. Austenitic grain growth was modeled as: Dinc5=D05+1.6×1032t⋅exp(-716870RT) using isothermal tests. Furthermore, an equation describing the dynamic recrystallized grain size was given as Ddyn = 3771·Z−0.2. The models of microstructural evolution could be applied to the numerical simulation of hot forging.