Reducing liquid metal embrittlement cracking in resistance spot welding of Q&P980 steel
Zhanxiang Ling, Ting Chen, Min Wang, Liang Kong
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.