2019 年 59 巻 1 号 p. 136-143
Fusion zone microstructural evolution of Al-10% Si coated hot stamping steel during laser welding and its mechanical properties were investigated in this study. During laser welding, a liquidized Al-10% Si coating penetrated along the fusion boundary to form δ-ferrite. After hot stamping heat treatment, the final microstructure was composed of a martensite-ferrite dual phase. The dual phase formation causes mixed mode fracture (brittle fracture + ductile fracture) at the fusion zone due to the hardness difference between the martensite and ferrite phases. This issue can be addressed by applying filler wire or by changing the coating system from an Al-based coating to a Zn-based coating.
