Effect of galvanneal coating evolution during press hardening on laser welding of 22MnB5 steel
ABSTRACT Understanding phase evolution and growth kinetics of Zn coating during press hardening is essential in predicting welding behaviour of press hardened 22MnB5 steel. The results showed that during press hardening, the initial d and G G1 phases in the coating transform into a Fe(Zn) G, and ZnO phases. As heat treating continued at a constant temperature, the a Fe(Zn) thickness grew and the overall Zn content decreased. This resulted in the full penetration weld window shifting towards higher heat inputs. However, when heat treating at higher temperatures, severe oxidation and Fe Zn inter diffusion led to the reduction of Zn content in the evolved coating. It was found that higher heat treatment times resulted in wider weld beads, thereby increasing joint strength.
Science and Technology of Welding and Joining