| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a high tensile steel material excellent in the hydrogen embrittlement resistant characteristics difficult to develop the hydrogen embrittlement of delayed fracture, welded delayed fracture, sulfide corrosion cracking, etc. SOLUTION: This producing method is performed as the followings, by which after quenching a steel slab composed by mass% of 0.02-0.25% C, 0.01-0.8% Si, 0.5-2.0% Mn, 0.005-0.1% Al, 0.0005-0.008% N,≤0.03% P,≤0.03% S, and if necessary, one or more kinds of Cu, Ni, Cr, Mo, Nb, V, Ti, B, Cu, REM, Mg and the balance Fe with inevitable impurities, from≥Ar<SB>3</SB>transformation point to≤temperature of [Si(mass%)×700+Cr(mass%)×50+250](°C), the tempering is performed at≥1°C/s average temperature rising velocity in the center part of the steel material from [Si(mass%)×700+Cr(mass%)×50+250](°C), desirably, the tempering is performed at <1°C/s average temperature rising rate in the center part of the steel material from the tempering starting temperature to [Si(mass%)×700+Cr(mass%)×50+250](°C). COPYRIGHT: (C)2006,JPO&NCIPI
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