Physical and Numerical Investigation of Hot Deformation Behavior in Medium-Mn Steel for Automotive Forgings

In this study, the hot deformation behavior of novel 0.17C-3.92Mn-1.02Si-0.53Al-0.22Mo-0.032Ti-0.069V steel during continuous compression was predicted using numerical simulation, providing a reference for optimizing the process. Medium-Mn steels have not been applied for forgings yet. Therefore, their industrial application requires detailed investigations on their hot deformability. Results of finite element (FEM) simulations will be used for further optimization of the press forging process. The material model parameters used in the FEM method were identified based on stress-strain curves registered during hot compression tests carried out using a Gleeble thermomechanical simulator. The numerical simulation and physical investigations were performed at temperatures of 900, 1000 and 1100 degrees C to reflect a range of temperatures occurring during press forging. The influence of strain rates of 0.05, 0.5 and 5 s-1 on the flow behavior of steel was also investigated. Colored maps of the plastic strain distribution in a sample volume were obtained as a result of the numerical research. The maps allowed for the identification of differently strengthened zones as a result of varied plastic strain. Results of FEM analysis were experimentally validated by hardness measurements. A good correlation between the hardness and plastic deformation zones was obtained. An increase in the material hardness was identified in the zones characterized by the highest plastic strain.