Determination of Liquid Metal Embrittlement After Resistance Spot Welding of Zn-Coated High-Strength Steels

Abstract

The weight reduction of vehicle body and parts become much more crucial to decrease CO2 emissions. The use of high-strength steels has increased within the scope of vehicle weight reduction studies. The corrosion resistance must be also ensured for automotive structural components. Therefore, zinc-coated high strength steels have been developed. Liquid metal embrittlement (LME) occurs during resistance spot welding (RSW) on zinc-coated high strength steels The liquid zinc from the coating penetrates along the grain boundaries in the material, where it leads to surface cracking. In this study, LME formation was investigated on zinc coated high strength steels during resistance spot welding (RSW). The effect of different type of zinc coating on LME formation was also considered. The results show that the type of zinc coating as well as the grade of the steel have considerable effect on LME formation. The maximum LME crack length was measured as 387 µm on GI coated Q&P 1180-Q&P 1180 welded joints by RSW.