Study on δ-ferrite evolution and properties of laser fusion zone during post-weld heat treatment on Al-Si coated press-hardened steel

Laser welding of Al-Si coated press-hardened steel (PHS) was still a challenging due to the formation of δ-ferrite in the fusion zone. However, it was ambiguous on the δ-ferrite evolution during post-weld heat treatment (PWHT). In this study, Al-Si coated PHS was welded by laser fiber and then heat-treated at various temperatures (650 °C, 950 °C and 1050 °C), and the microstructure evolution was investigated by in situ-observation. Mechanical …