Enhanced mechanical performance of 0.13C-7Mn TRIP steel welds with optimized tempering

In response to the brittleness issues of 0.13C-7Mn TRIP steel welds, a heat treatment process with varying holding times was designed. This study investigates the effects of tempering on the microstructure and mechanical properties of the welds. After holding at 250 °C for 10, 20, and 30 min, the peak load in tensile shear tests increased by 89.6%, 104.8%, and 41.6%, respectively, compared to the samples that were not tempered. Furthermore, the failure mode transitioned from complete brittle interfacial fracture (IF) to more ductile modes, including partial interfacial fracture (PIF) and pull-out fracture (PF). After tempering, the martensite in the weld zone transforms into tempered martensite. The hardness of both the heat-affected zone and the fusion zone (FZ) decreased by approximately 20 HV, leading to a more uniform hardness distribution, leading to a more uniform hardness distribution. Additionally, the segregation of manganese (Mn) in the fusion zone is also mitigated.