| 摘要 |
PURPOSE:To obtain a steel for a line pipe having excellent sour resistance by specifying the compsn. consisting of C, Si, Mn, Al, P, S, Ca, Se and Fe. CONSTITUTION:The titled steel contains, by weight, 0.01-0.25% C, 0.010-0.50% Si, 0.70-2.00% Mn, 0.01-0.10% Al, <=0.030% P, <=0.0030% S, 0.0005-0.0050% Ca and 0.01-0.50% Se, furthermore contains at need one or more kinds among 0.10-0.60% Cu, 0.10-3.0% Ni, <=5.0% Cr, <=2.0% Mo and <=0.10% Ti and/or one or more kinds among <=0.10% Nb, <=0.15% V, <=0.10% Zr and <=0.005% B and consists substantially of the balance Fe. The penetration of hydrogen into the steel is decreased, by which hydrogen induced cracking resistance is improved and the steel has sufficient sulfide stress corrosion cracking resistance. The reliability of a line pipe in an H2S contg. low pH environment can be improved, in the above-mentioned manner.
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