| 摘要 |
PURPOSE:To obtain a high toughness seamless steel pipe by subjecting a steel contg. specified amounts of C, Si, Mn and Al and restricted amounts of P and S as impurities to direct quenching and tempering. CONSTITUTION:A high toughness seamless steel pipe is obtd. by subjecting a steel consisting of, by weight, 0.01-0.08% C, 0.10-0.50% Si, 0.50-2.00% Mn, 0.001-0.100% Al, <=0.010% P and <=0.0020% S as impurities and the balance Fe with other inevitable impurities or further contg. one or more among <=0.50% Cu, <=1.0% Ni, <=0.030% Ti, <=0.0030% B and <=0.0060% Ca to direct quenching and tempering. The high toughness is provided by regulating the chemical composition.
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