The Zn-rich corner of the Zn-Al-Fe phase diagram for use in continuous galvanizing

As thinner, higher strength sheet steels are increasingly used in automotive designs for improved fuel efficiency, corrosion protection by metallic coating is required in order to maintain the vehicle's appearance and structural integrity. In order to realise these goals, in has become imperative that good control of the continuous galvanizing process be maintained. A key ingredient for this is control of the galvanizing bath dissolved or effective Al, which is dictated by the Zn-rich comer of the Zn-Al-Fe phase diagram. This paper will present a combination of experimental data and a comprehensively revised thermodynamic model to describe the system. In particular, the model recognises the non-stoichiometry of the delta and eta intermetallic phases and incorporates revised values for the thermodynamic properties of Fe and Al dissolved in molten Zn.