Study on Performance of Al-Si Coated Hot-Formed Steel Plate Hot Filler Laser Tailor Welding Joint

The hot-formed steel plates with Al-Si coating was welded by using hot filler laser tailor welding, then it was hot formed and quenched in dies.The microstructure, Al element distribution and mechanical properties of the welded joint were investigated.The results show that the microstructure of the substrate is martensite and the microstructure of weld nugget zone consists of martensite, ferrite and bainite; the Al element is uniformly distributed in the weld and no accumulation of Al element occurs, and the average content of Al element is about 0.87%.The hardness of weld nugget zone and substrates is 475, 501 HV respectively.The strength of weld and substrates is basically same, however, there are some differences in elongation after fracture, which is caused by the uneven deformation of weld and substrates during tensile process.