| 摘要 |
PURPOSE: To provide a precoated steel sheet for automobile having corrosion resistance, especially excellent end face corrosion resistance and favorable workability by specifying composition, coating weight and film thickness of each film in a steel sheet forming a zinc plated film, a chromate film, an under coating film and further a top coat film in these orders on both surfaces of the steel sheet respectively. CONSTITUTION: This precoated steel sheet for automobile has the zinc plated film on both surfaces of the sheet and thereon has 10-150mg/m<2> of the chromate film in terms of Cr amount. Thereon the sheet has a thickness 5-10μm of an under coating film containing by weight to a total solid content weight of a paint, 10-60wt.% chromium base rust preventive pigment and 0.5-20wt.% water- soluble organic inhibitor and further thereon has a thickness 5-35μm of the top coat film. Thus, because of its containing the water-soluble organic inhibitor together with the chromium, the organic inhibitor is also supplied the chromium base rust preventive pigment and inhibits a together with corrosion, when chromic acid ions from the chromium base rust preventive pigment are supplied to the steel sheet end face.
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