| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot rolled steel sheet, a cold rolled steel sheet, and a plated steel sheet, all being soft in the forming process and excellent in abrasion resistance in the use; their production methods; and methods for producing working (sliding) members using the above steel sheets. SOLUTION: Steel containing 0.05-0.25 mass% C, 3.0 mass% or lower Si, 0.5-3.0 mass% Mn, 0.01 mass% or lower S, 0.002 mass% or lower Al, and 0.0030-0.025 mass% N is hot rolled at a slab heating temperature of 1,000°C or higher, a finish-rolling outlet temperature of 800°C or higher, a cooling rate of 40°C/sec or higher, and a hot-rolling winding temperature of 650°C or lower, thus giving a steel sheet of which the structure contains at least 60 area% ferrite phase having an average particle size of 10μm or lower and which has a tensile strength of 590 MPa or lower and such age hardening characteristics that BH is 80 MPa or higher andΔTS is 40 MPa or higher. After the steel sheet is subjected to punching or after working with an equivalent strain of 0.05 or higher is applied to the sliding section, the steel sheet is heat-treated at 100-300°C for 30 sec to 20 min. COPYRIGHT: (C)2003,JPO
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