Fracture prediction of powder metallurgical Fe–Cu–C steel at elevated temperatures via finite element-aided hot tensile tests

Surface cracking induced by damage accumulation is a common quality problem during the hot processing of powder metallurgical (P/M) products. This study aims to clarify the damage and fracture of P/M Fe–Cu–C steel at elevated temperatures to propose its fracture criterion by combining hot tensile tests with finite element (FE) calculations. The results reveal that the FE-aided test accurately corrected the true stress and strain of the P/M steel during the Gleeble hot tensile testing. In addition, the flow behaviors and cracking tendency of the P/M steel strongly depended on the hot deformation parameters. The optimum hot processing window of P/M steel was proposed after determining the quantitative relationships between the damage and hot deformation parameters. Finally, a novel elevated temperature fracture strain model of the P/M steel was proposed based on the Zener–Hollomon parameter to construct its Cockroft and Latham fracture criterion coupling hot processing parameters. The constructed fracture criterion was further normalized and modified, and achieved an acceptable fracture predictive capability with a relative error of less than 5%, which was validated by powder forging experiments. This work provides essential information and a useful model for the fracture prediction of P/M Fe–Cu–C steel at elevated temperatures, helping to manage the surface cracking problems of P/M steel during hot processing.