Effect of Stamping Temperature on Cracks in Coating of Galvanized 22MnB5 Steel Plates

The cracks in the coating of galvanized 22MnB5 steel plates formed at different stamping temperatures were studied by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that homogeneous austenitization at 900℃ for 5min of the steel plates could improve the Fe content in the coating, and Zn liquid was transformed into solid α-Fe (Zn) to avoid the occurrence of liquid metal induced embrittlement (LMIE) cracks in high temperature stamping process. The Zn content in the coating after stamping was 25%-30% (atom), which could provide good cathodic protection for the substrate. It was helpful to reduce LMIE cracks in the coating when the stamping temperature was below the melting point of Γ phase (782℃).