The Influence of Additional Ni and Cu in Steel on the Galvanizability and Oxidation State of Si, Al, Mn Bearing Steels

Si, Al and Mn are readily oxidizable elements, then Si, Al, Mn steels have the drawback of poor galvanizability due to the presence of complex Si–Al–Mn oxides on their surface. In order to improve the galvanizability of Si, Al, Mn steels, the effect of the addition of Ni and Cu on the wettability and galvannealing kinetics has been investigated. It was shown that the addition of Ni and Cu improved wettability and increased the galvannealing rate. This improvement was due to the change of the sub-micron oxide morphology just before the galvanizing treatment. In the case of C, Si, Al, Mn steel a film of Si–Al–Mn oxide was formed. The addition of Ni and Cu made Si–Al–Mn oxide intermittent and internal oxide formed remarkably.