ABSTRACT The galvanized ultra-high-strength steels are prone to liquid metal embrittlement (LME) cracking during resistance spot welding (RSW), cracking is facilitated by the specific temperature and stress conditions on the steel surface. A two-dimensional electro-thermomechanical model was established to simulate the RSW of a galvanized Q&P980 steel, which was susceptible to LME. Temperature and stress histories in the welding area were obtained from simulation, they could well explain the occurrence of LME. A mild steel cover sheet was used during welding, which was placed between the Q&P980 steel and the electrode. It was found that the cover sheet modified the temperature and stress states on the surface of Q&P980 steels and made them less satisfying to LME, and consequently suppressed LME cracking.

中文翻译：

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减少Q&P980钢电阻点焊中液态金属脆化开裂

摘要 镀锌超高强钢在电阻点焊（RSW）过程中容易发生液态金属脆化（LME）开裂，开裂是由钢表面特定的温度和应力条件促进的。建立二维电热机械模型来模拟镀锌 Q&P980 钢的 RSW，该钢易受 LME 影响。焊接区的温度和应力历程是通过模拟获得的，它们可以很好地解释LME的发生。焊接过程中使用低碳钢盖板，将其放置在 Q&P980 钢和焊条之间。结果表明，覆盖板改变了 Q&P980 钢表面的温度和应力状态，使它们对 LME 不太满意，从而抑制了 LME 开裂。