Nickel alloy electroplated cold-rolled steel sheet excellent in

Abstract

A method for manufacturing a nickel alloy electroplated cold-rolled steel sheet excellent in press-formability and phosphating-treatability, which comprises the steps of: (a) cold-rolling a hot-rolled steel sheet at a reduction ratio of from 60 to 85% to prepare a cold-rolled steel sheet consisting essentially of: up to 0.06 wt. % carbon, up to 0.5 wt. % silicon, up to 2.5 wt. % manganese, up to 0.1 wt. % phosphorus, up to 0.025 wt. % sulfur, up to 0.10 wt. % soluble aluminum, up to 0.05 wt. % nitrogen, and the balance being iron and incidental impurities; then, (b) subjecting the cold-rolled steel sheet to a continuous annealing treatment which comprises heating the cold-rolled steel sheet to a recrystallization temperature and then slowly cooling same; then, (c) forming, on at least one surface of the annealed cold-rolled steel sheet, a nickel alloy electroplating layer having a plating weight of from 5 to 60 mg/m.sup.2 in an acidic electroplating layer, the nickel alloy electroplating layer consisting essentially of nickel alloy particles precipitated at a distribution density of at least 1.times.10.sup.12 /m.sup.2, the nickel alloy particles containing at least one of phosphorus, boron and sulfur in an amount of from 1 to 15 wt. %; and then, (d) immersing the thus nickel alloy electroplated cold-rolled steel sheet into a neutral bath or an alkaline bath to form a nickel alloy oxide film having an average thickness of from 0.0002 to 0.005 .mu.m on the nickel alloy electroplating layer.