Coating microstructure development during Zinquench galvanising of sheet steel

The influence of an elevated strip entry temperature on the kinetics of the galvanising reaction has been investigated for a titanium stabilised, interstitial free steel. Elevated strip entry temperatures (>550°C) have been shown to accelerate greatly alloying between the substrate and the molten zinc, increasing the growth rate of the δ phase from 1 to ∼7 μm s - 1 and preventing the formation of the ζ phase. The substantial Fe-Zn phase layer seen at the coating/substrate interface at high strip entry temperatures (>550°C) is attributed to the dissolution of iron from the substrate into the molten zinc in the first second of immersion, and the limited inhibition provided by the bath aluminium content (