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.

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