| 摘要 |
PURPOSE:To produde high strength steel for oil wells having excellent resistance to sulfide stres corrosion cracking, by subjecting the steel contg. limited compsn. amts. of C, Si, Mn, Cr, Co, Al, etc. and limited with contents of unavoidable impurities to heat treatments suitably. CONSTITUTION:The steel contg. 0.15-0.50% C, 0.1-1.0% Si, 0.3-1.5% Mn, 0.1- 2.20% Cr, 0.1-5.0% C0, 0.001-0.1% Al, and limited with contents of P, S, Mo, and W as unavoidable impurities at <=0.025% P, <=0.010% S, <=0.050% Mo, and <=0.050% W, respectively is heated to temp. of the Ac3 transformation temp. or above, and is then hardened to the temp. within the temp. range of the Ms transformation point 100 deg.C and is held at these temps. for 1min. In succession, the steel is subjected to a tempering treatment at temp. of the Ac1 transformation point or below, whereby the high strength steel for oil wells which has the texture consisting essentially of tempered bainite texture, has >=70kg/mm.<2> yield strength and is highly resistant to sulfide stress corrosion cracking is obtained. |
