In this present, hot-rolled Al-Si coated press hardened steel (PHS) with 1.5 mm thick was laser tailor welded using Ni foil as an interlayer. The effect of Ni foil thickness on the microstructure evolution of fusion zone (FZ) was studied. With the Ni foil thickness increased, Al had a uniform profile in the FZ but Ni had a segregation in the fusion boundary. JMatPro analysis results showed that the fraction of δ-ferrite at high temperature was decreasing and the primary solidification phase was changed from δ-ferrite to γ phase. The fusion boundary and FZ center had the similar solidification phase evolution during laser welding. The microstructure was the composition of δ-ferrite and lath martensite when the Ni foil was 30 μm, but it was full martensite with the Ni foil increased to 60 μm. Austenite was present in the fusion boundary with the Ni foil increased to 100 μm but it was still lath martensite in FZ center.

在本发明中，使用Ni箔作为中间层对1.5mm厚的热轧Al-Si涂层的加压硬化钢（PHS）进行激光拼焊。研究了镍箔厚度对熔合区（FZ）组织演变的影响。随着Ni箔厚度的增加，Al在FZ中具有均匀的轮廓，而Ni在熔合边界处偏析。JMatPro分析结果表明，高温下δ铁素体的含量下降，一次凝固相从δ铁素体转变为γ相。熔接边界和FZ中心在激光焊接过程中具有相似的凝固相演变。显微组织是δ的组成Ni箔为30μm时，铁素体和板条马氏体，但Ni箔增加至60μm时为全马氏体。Ni箔厚度增加到100μm时，奥氏体存在于熔合边界，但在FZ中心仍为板条马氏体。