| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a high-strength cold-rolled steel sheet which has excellent chemical-processing property and corrosion-resistance after electrostatic-deposition coating even in the case of a comparatively high content of Si. SOLUTION: The cold-rolled steel sheet containing Si of 0.8-2.0 mass%, and Mn of 1.0-3.0 mass%, is first subjected to annealing in atmosphere of N<SB>2</SB>-H<SB>2</SB>in a furnace and at a ratio of PH<SB>2</SB>O/PH<SB>2</SB>of≤1.0×10<SP>-3</SP>. Successively, a quenching and a tempering, are applied, and thereafter, a pickling is performed with an alternating current electrolysis having≥1A/dm<SP>2</SP>current density. After passing through such sequential process, the high-strength cold-rolled steel sheet having strength of≥590 MPa TS and excellent in the chemical-processing property and the corrosion-resistance after electrostatic-deposition coating, is obtained. COPYRIGHT: (C)2010,JPO&INPIT
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