METHOD FOR MANUFACTURING COLD-ROLLED STEEL SHEET EXCELLENT IN TERMS OF CHEMICAL CONVERTIBILITY AND POST-COAT CORROSION RESISTANCE AND FAVORABLE IN TERMS OF SLIDABILITY

摘要

PROBLEM TO BE SOLVED: To provide a method for manufacturing a cold-rolled steel sheet excellent in terms of chemical convertibility and post-coat corrosion resistance and favorable in terms of slidability.SOLUTION: A cold-rolled steel sheet including 0.5-2.0 mass% of Si is thermally annealed within a non-oxidative atmosphere, and after at least 0.5 g/mof the surface of the cold-rolled steel sheet has subsequently been dissolved via an acid wash, a Zn-Ni alloy having an Ni content of 5 wt.% or above and 20 wt.% or below is electrodeposited on the cold-rolled steel sheet surface at an adhesion rate of 100-5000 g/m. The heating temperature of the thermal annealing is 900°C or below. The non-oxidative atmosphere is obtained by introducing a gaseous mixture of nitrogen and hydrogen. It is desirable for the hydrogen content of the non-oxidative atmosphere to be 10 vol.% or less.