ABSTRACT
The microstructure and mechanical property of improved press-hardened steel with hot pressing combined dynamic partitioning (HP-DP) treatment are presented. Microstructure of the steel subjected to HP-DP treatment is featured by multi-martensite phases and the retained austenite (RA) phase with carbon content gradient. Compared with conventional hot-pressed samples, the HP-DP samples show better tensile property especially ductility. The effect of HP-DP parameters on the evolution of RA and mechanical property is then discussed. Finally, hot pressing of a double U-shaped part using both 22MnB5 steel sheet and the developed HP-DP steel sheet was carried out with exact control of part temperature at the end of hot pressing followed by air cooling.
Disclosure statement
No potential conflict of interest was reported by the authors.