| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a steel material excellent in a uniform elongation characteristic and a fatigue crack propagation characteristic. <P>SOLUTION: This method of manufacturing the steel material is constituted to heat, at temperature of 950°C to 1,200°C, steel containing, by mass%, 0.10 to 0.16% of C, 0.10 to 0.50% of Si, 0.8 to 1.2% of Mn, 0.05% or less of P, 0.02% or less of S and 0.05% or less of Nb, and containing, when required, one, two or more of kinds of metal components selected from the group comprising 0.4% or less of Cu, 0.8% or less of Ni, 0.4% or less of Cr, 0.4% or less of Mo, 0.05% or less of V, 0.03% or less of Ti and 0.003% or less of B, with the remainder comprising Fe and inevitable impurities, and satisfying Ceq=0.40, to be thereafter rolled by 50% or more of cumulative reduction at Ar<SB POS="POST">3</SB>or more, and accelerated cooling is started at a cooling speed of 10°C/s or more and less than 30°C/s, from an temperature zone of the Ar<SB POS="POST">3</SB>or less satisfying Ar<SB POS="POST">3</SB>-60°C and 730°C or more, and is stopped at 500°C to 650°C. <P>COPYRIGHT: (C)2012,JPO&INPIT |
