Effect of Ni-interlayer on zinc-assisted liquid-metal-induced-embrittlement susceptibility of 22MnB5 galvanized steel

Abstract

In this study, in-situ heat treatment and high-temperature tensile tests were performed to investigate the effect of an Ni-interlayer on the zinc-assisted liquid-metal-induced-embrittlement (LMIE) susceptibility of 22MnB5 galvanized steel. The heat treatment results indicated that the Ni-interlayer delays the diffusion between liquid Zn and steel substrate, and it can modify the phase composition of the coating. The high-temperature tensile test results showed that the strength and ductility of the 22MnB5 galvanized steel increased as the Ni-electroplating time increased, indicating that the Ni-interlayer could improve the strength and ductility of the 22MnB5 galvanized steel. The fracture type of the galvanized steel was brittle, while that of the Ni-interlayer galvanized steel was ductile, additionally, a U-shaped crack extending to the steel substrate was observed near the fracture of the galvanized steel, whereas no cracks extending to the steel substrate were observed near the fracture of the Ni-interlayer galvanized steel. In general, the Ni-interlayer can reduce the susceptibility of zinc-assisted LMIE; moreover, when the Ni layer was electrodeposited for 8 min, the property of the Ni-interlayer galvanized steel was found to be comparable to those of bare steel.