| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for manufacturing a high strength cold rolled steel sheet excellent in chemical conversion treatment property and corrosion resistance after coating.SOLUTION: A cold rolled steel sheet containing 0.5 to 2.0 mass% of Si is heating annealed under non-oxidative atmosphere, a surface of the cold rolled steel sheet is dissolved at 0.5 g/mor more by acid cleaning, and then electric plating of a Zn-Fe alloy having the Fe percentage content of 50 wt.% to 98 wt.% is performed with a coating weight of 1000 to 5000 mg/m. The heating annealing is at a heating temperature of 900°C or less, the non-oxidative atmosphere is obtained by introducing a mix gas of nitrogen and hydrogen, and the content of hydrogen in the non-oxidative atmosphere is preferably 10 vol.% or less. |
