Theoretical prediction of high strength steel 22MnB5 forming limit in high temperature based on M-K model

Hot stamping is an advanced manufacturing process in automobile manufacturing. Different from the traditional forming process in room temperature, the strain hardening, temperature, strain rate and microstructure of the material have great influence on the mechanics and failure behavior of the high strength steel. The traditional theoretical forming limit prediction method based on room temperature is not effective enough to predict the formability of parts under hot stamping condition. A forming limit prediction model for the high temperature forming process of 22MnB5 is obtained based on Norton-Hoff constitutive model, BBC 2005 yield criterion, and M-K model. The accuracy of the prediction model is verified by comparing with the experimental data in the literature. This model can be used as the forming limit prediction criterion for high strength steel in hot stamping process. The characteristics of forming limit curves under different conditions are obtained and the effect of yield criterion, temperature, and strain rate are summarized.