Abstract
In order to evaluate the galvanisability of a CMnSiCr DP780 steel, which is originally designed for manufacturing continuously annealed bare steel sheet, hot-dip galvanising experiments were conducted on a hot-dip process simulator. The process and galvanising behaviours were investigated. The results indicate that the alloying elements such as Si, Mn and Cr segregate and selectively oxidise at the surface during annealing. Besides external oxidation, internal oxidation of Cr and Mn is observed. Aluminothermic reducing reaction is effective to reduce the negative effect of surface oxides on the galvanisability of this steel and improve the coating quality. According to the measurement results and discussions, it is believed that this CMnSiCr DP780 steel could possibly be used to produce the corresponding hot-dip galvanised or galvannealed product when further increasing the Al content in Zn bath slightly, especially for galvannealed product.
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