Abstract
Hot dip galvanised steels with thermal treatment or galvannealed steels are used in automotive industries because of their properties of weldability, workability and corrosion resistance. The galvannealed steels show three iron–zinc phases: zeta, delta and gamma. The distribution and concentration of iron–zinc phases affect the quality of the zinc layer and can produce stamping and welding problems. In the present work, the optimisation study of the electrochemical stripping process of industrial galvannealed steel was performed. The effect of electrolyte, pH, current density and scan rate was evaluated. The best resolution of the potential levels in the electrochemical dissolution curves was obtained for the zinc sulphate heptahydrate and sodium chloride aqueous solution, with a current density of 2 mA cm−2 and pH 4·5. Each sample surface obtained by using electrochemical stripping was analysed using X-ray diffraction and scanning electron microscopy.
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