Abstract
The effect of accelerated oxidation prior to annealing on the galvanizability of 1.4 mass%Si-bearing steel was investigated. Oxidation process accelerated by ammonium sulfate improved the galvanizability of the steel under the oxidation condition where the steel without ammonium sulfate showed poor galvanizability: iron oxides containing more than 0.42 g•m−2 oxygen were found to improve the galvanizability. Iron oxides produced during accelerated oxidation prior to annealing improved the galvanizability because a continuous pure reduced iron layer formed on the surface of the steel was free of the surface segregation of silicon and manganese during annealing. This is because silicon and manganese were internally oxidized beneath the reduced iron layer as silica and complex oxides of silicon and manganese by oxygen in iron oxides. It is proposed that the amount of iron oxides required for the improvement of galvanizability is that of iron oxides which can supply that of oxygen required for capturing silicon and manganese as the internal oxides during annealing.
