Critical stress required for liquid metal embrittlement (LME) crack initiation: damage mapping for LME cracks in resistance spot welding (RSW) through in-situ monitoring

Liquid metal embrittlement (LME) poses a significant challenge in the automotive industry because it can cause circumferential surface cracks adjacent to the weldment, especially when resistance spot welding (RSW) third-generation advanced high-strength steels (3G-AHSS). Numerous studies aim to predict the onset of LME cracks during welding. Gleeble hot-tension tests are often used to understand the LME crack mechanism, including identifying the critical stress at various temperatures. An investigation developed a finite element method (FEM) to predict LME cracks; however, validation against actual welding conditions remains limited. This research assesses the critical stress from in-situ welding observations at temperatures ranging from 594 °C to 786 °C and compares these results to those from Gleeble tests. Findings indicate that the critical stress obtained from Gleeble tests directly correlates with the critical stress necessary to initiate LME crack during welding.