ZINC-BASED METAL PLATED STEEL SHEET TREATED WITH PHOSPHATE BEING EXCELLENT IN FORMABILITY AND METHOD FOR PRODUCTION THEREOF

摘要

A zinc-based metal plated steel sheet treated with a phosphate which comprises a zinc-based metal plated steel sheet and, on the surface thereof, a film formed by treating the surface with a phosphate, characterized in that the film comprises granular crystals as its main constituent and, preferably, the crystals have an average ratio of a long axis to a short axis of 1.00 to 2.90; and a method for producing the plated steel sheet, characterized as comprising subjecting a zinc-based metal plated steel sheet to a phosphate treatment using a phosphate treatment solution having an Mg ion content of 6 g/l or more and a Zn ion content of 0.5 g/l or more, or a solution having an Mg ion content of 10 mg/m<2> or more, a Zn ion content less than 0.5 g/l and a phosphoric ion content of 40g/l or more. The zinc-based metal plated steel sheet is advantageous in that it exhibits excellent formability. Further, a zinc-based metal plated steel sheet having also excellent corrosion resistance is provided by using a phosphate treatment solution having a content of Mg ion of 10 g/l or more, and that having also excellent weldability is provided by controlling an amount of the film to 0.5 to 3.0 g/m<2>.