Metastable material conditions for forming of sheet metal parts combined with thermomechanical treatment

Developments of new forming processes become increasingly complex due to the combination of thermomechanical treatment and advanced forming technologies in manufacturing sheet metal parts. The development of this technology is coupled with better understanding of the thermomechanical behaviour of the implemented alloys in this process such as hardenable low carbon steels alloyed with austenite-stabilizing elements. Complex process conditions such as high heating rates in combination with plastic deformation, as well as cooling processes are investigated for boron-manganese steel 22MnB5. Contrary to conventional hot stamping processes, metastable material conditions are considered and subsequently implemented. Advantages are found such as increasing formability, lowered forming forces and enhanced material properties in formed components. The obtained results are successfully implemented in innovative forming processes, for example roll forming with integrated heat treatment and cushion-ram-pulsation (CRP) hot stamping processes.