Liquid Metal Embrittlement (LME) of High-Strength Steels During Spot Welding: A Review

Abstract

During resistance spot welding, molten zinc promotes the brittleness of galvanized high-strength steels and hence produces surface cracks. This study introduces a view of LME of high-strength steels, what are the reasons behind LME to occur, and the mechanisms for LME. In this review, the types of LME cracks, macroscopic and microscopic studies of cracks, and the location of cracks of Zn-coated steels are discussed. Also, a view of factors that influence the LME like the type of coating, welding conditions, alloying elements and electrode geometry, electrode force, temperature, stress is considered. It is observed that hot-dip galvanized coating, increase in welding current and time, decrease in holding time, lower electrode force, misalignment between the electrodes and workpieces, increase in alloying content (Si, Mn, Al) showed high LME sensitivity. Finally, the useful techniques to reduce crack preference during welding are identified. © 2022, The Indian Institute of Metals - IIM.