ABSTRACT Resistance spot welding (RSW) process with protective coatings on advanced high-strength steels is a challenge. An ultimate tensile strength (UTS)1500 MPa grade hot stamping sheet steel(22MnB5) with Al–Si coating was employed for the RSW process in the present study. The effects of Al–Si coating on the microstructure of RSW joints and tensile-shear fracture behaviour were investigated. Strip-like Fe-(Al,Si) cladding on the surface of nugget tongues acted as the crack source and initiated the fracture. Two types of fatigue failure mode were observed: nugget pull-out with tearing of base material (BM) and eyebrow-shaped fracture along the BM width direction, corresponding to high and low loading levels, respectively. All fatigue fracture cracks were found to be originated along the Fe-(Al,Si) strip through the heat-affected zone.

中文翻译：

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Al-Si涂层电阻点焊热冲压钢板的拉伸剪切断裂行为

摘要 在高级高强度钢上采用保护涂层的电阻点焊 (RSW) 工艺是一项挑战。在本研究中，极限拉伸强度 (UTS) 1500 MPa 级热冲压钢板 (22MnB5) 与 Al-Si 涂层被用于 RSW 工艺。研究了Al-Si涂层对RSW接头微观结构和拉伸剪切断裂行为的影响。熔核舌表面的条状Fe-(Al,Si)熔覆层作为裂纹源并引发断裂。观察到两种类型的疲劳失效模式：带基材 (BM) 撕裂的熔核拉出和沿 BM 宽度方向的眉形断裂，分别对应于高载荷和低载荷水平。发现所有疲劳断裂裂纹都起源于通过热影响区的 Fe-(Al,Si) 带材。