| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot-pressing method capable of efficiently manufacturing a component of excellent shape and high strength. SOLUTION: The hot-pressing method for hot-pressing a steel plate having a chemical composition consisting of, by mass, ≥0.08% and ≤0.45% C, ≥0.5% and ≤3.0% the total of Mn and Cr, and the balance optional additives other than C, Mn and Cr, Fe and inevitable impurities, and heated to the temperature of equal to or higher than Ac3 point by a die from the press-starting temperature equal to or higher than Ar3 point, includes a step of cooling the steel plate to the temperature of ≥200°C and ≤(Ms-120)°C at the cooling rate of the critical cooling rate of the steel plate while restraining the steel plate at the bottom dead center of the die, and the steel plate is taken out of the die, the restraint is started by a means different from the die before the temperature drop of the steel plate after the completion of restraint at the bottom dead center by the die is ≥15°C, and the steel plate is cooled to the temperature <200°C. COPYRIGHT: (C)2011,JPO&INPIT
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