| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a high carbon hot-rolled steel sheet containing≥0.5 mass% C and having excellent workability and hardenability, while being reduced in variations of the characteristics in the steel sheet. SOLUTION: The method for producing the high carbon hot-rolled steel sheet, includes: hot-rolling a steel billet having the composition composed of, by mass%, 0.5-1.0% C,≤2.0% Si,≤2.0% Mn,≤0.03% P,≤0.03% S,≤0.08% sol. Al,≤0.01% N and the balance Fe with unavoidable impurities, at a finishing temperature of an Ar<SB>3</SB>transformation point or an Ar<SB>cm</SB>transformation point or higher; primarily cooling the hot-rolled sheet to the cooling-stop temperature of 550-650°C at≥60°C/s average cooling rate; then, air cooling the hot-rolled sheet; successively, performing secondary cooling to the cooling-stop temperature of 500-600°C at≥120°C/s average cooling rate and winding up the sheet; and thereafter, annealing the sheet at the temperature of≥640°C to an Ac<SB>1</SB>transforming point or lower. COPYRIGHT: (C)2011,JPO&INPIT
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