| Abstract Scope |
Joining advanced high strength steels (AHSS) via resistance spot welding (RSW) is a common process in the automotive industry that can exhibit liquid metal embrittlement (LME)-induced cracking. Process atmosphere and resulting oxidation mode, steel composition, and Zn-based sacrificial coating chemistry all impact RSW success, but have not been studied concurrently. Additionally, research was conducted primarily on electrogalvanized Zn coated samples, which are not representative of real-world conditions. This study, with observations of the Zn-steel interface via FIB-SEM, EBSD, TEM, and APT, determines the effects of these factors on LME in four low-C high-Si substrate compositions, two Zn-based coatings (pure Zn or Zn-0.2Al), and two atmosphere-induced oxidation modes. Hot tensile testing, which replicates RSW cycles, showed internally oxidized steels improved resistance to LME cracking. Steels exhibited little LME with electrogalvanized coatings, yet significant LME with galvanized coatings. This investigation signals a potential solution to the premature failure of AHSS under RSW. |