In this study, the influence of the microstructural evolution of galvannealed (GA) coating and the thermomechanical characteristics of liquid metal embrittlement (LME) cracking during resistance spot welding (RSW) of steels were investigated. The analysis of LME cracks, coating microstructure and thermomechanical characteristics at various weld regions revealed a synergistic effect of liquid Zn, α-Fe(Zn), and tensile stress on LME cracking during RSW. A continuous α-Fe(Zn) layer inhibits liquid Zn from contacting the steel substrate; hence, LME was suppressed. However, a long-duration, high-magnitude tensile stress can fragment the α-Fe(Zn) layer and enable LME cracking. Conversely, α-Fe(Zn) particles allow the easy infiltration of liquid into the steel and make the crack on tensile stress development.

在这项研究中，研究了镀锌（GA）涂层的组织演变以及钢在电阻点焊（RSW）过程中液态金属脆化（LME）开裂的热机械特性的影响。对不同焊接区域的LME裂纹，涂层微观结构和热机械特性的分析揭示了液态Zn，α-F​​e（Zn）和拉伸应力对RSW期间LME裂纹的协同作用。连续的α-Fe（Zn）层可抑制液态Zn与钢基材的接触。因此，LME被抑制。但是，长时间的高强度拉伸应力会使α-Fe（Zn）层破碎，并使LME破裂。相反，α-Fe（Zn）颗粒使液体易于渗入钢中，并在拉伸应力发展时产生裂纹。