Effect of Silicon in Dual Phase Steel on the Alloy Reaction in Continuous Hot-dip Galvanizing and Galvannealing

The mechanical properties of steels can be significantly improved by alloying with Si. However, Si in dual phase steel retarded the alloy reaction in hot-dip galvanizing and galvannealing; specifically, a continuous Fe–Zn alloy layer was absent on the steel containing 0.44 wt% Si after 25 s of galvannealing at 500°C. This retardation may be due to the Si-rich molten Zn layer, in which the Si resulted from the aluminothermic reduction of Si oxide and the dissolution from the steel substrate.