Average austenite grain size evolution simulation during multi-pass shape metal hot rolling process

Constitutive equations describing the flow stress of Q235 steel undergoing hot plastic deformation have been developed by integrating the microstructure models and exponential flow stress models presented in literatures, in which the microstructure models parameters have been re-determined based on the related experiments carried out on cylindrical specimens of the Q235 steel. Therefore, the integrated constitutive equations are capable of calculating the evolution of austenite grain size and investigating the effects of average austenite grain size on the flow stress of Q235 steel during hot deformation. A three-dimensional thermo-mechanically coupled FEM simulation of an 11-pass H-shape metal roughing rolling process with the austenite grain size evolution taken into account have been carried out to verify the rationality of roll pass schedule. The accuracy of the integrated constitutive equations has been preliminary validated by the comparisons between measured and the calculated values of rolling force.