ZN-CR-P ORGANIC COMPOSITE PLATED STEEL SHEET HAVING EXCELLENT POST-WORKING CORROSION RESISTANCE, ED COATING CORROSION RESISTANCE AND END FACE RUST PREVENTIVENESS

摘要

PURPOSE: To provide the Zn-Cr-P org. composite plated steel sheet having excellent post-working corrosion resistance, ED coating corrosion resistance and end face rust preventiveness. ;CONSTITUTION: The org. composite plated steel sheet having the excellent post-working corrosion resistance, ED coating corrosion resistance and end face rust preventiveness is constituted by having an electroplating layer of a Zn-Cr-P alloy having 5 to 14% Cr concn. and over 0.5 and ≤30%P concn., having ≥2 and ≤20 Cr/P ratio and consisting of the balance Zn and by having a chromate layer thereon and further coating the surface thereof with an org. resin. The extremely dense chromate film is formed by the effect of the Cr and the P if the Zn-Cr-P alloy plating having the specific concns. shown above is subjected to a chromate treatment, by which the corrosion resistance of the Zn-Cr-P alloy is greatly improved. In addition, the chromate film is protected over a long period of time and the overwhelming corrosion resistance is assured if the org. film is formed thereon. The coating corrosion resistance and the end face rust preventiveness are assured by the excellent adhesive strength of the chromate film.;COPYRIGHT: (C)1993,JPO&Japio