PRODUCTION OF ZINC-NICKEL ALLOY PLATED STEEL SHEET EXCELLENT IN SECONDARY ADHESION RESISTANCE TO WATER AND CORROSION RESISTANCE AFTER COATING

摘要

PROBLEM TO BE SOLVED: To provide a method for producing a Zn-Ni alloy plated steel sheet by which a Zn-Ni alloy plated steel sheet excellent in secondary adhesion resistance and corrosion resistance after coating to water can stably be produced without being influenced by a line velocity. ;SOLUTION: After Zn-Ni alloy plating film is formed on at least one side of a steel sheet by Zn-Ni alloy plating, a post-treating soln. of pH2.5 to 4.5 contg. one or more kinds selected from among H₂PO₄^-, HPO₄^2- and H₃PO₄ by 15 to 170g/l as the concn. of P, furthermore contg. 1 to 50g/l Ni and 0.3 to 10g/l Co, and in which the soln. temp. is preferably regulated to 40 to 70°C is brought into contact with the Zn-Ni alloy plating film.;COPYRIGHT: (C)1998,JPO