HIGH STRENGTH UOE LINE PIPE EXCELLENT IN SULFIDE STRESS CRACKING RESISTANCE IN WELD ZONE

摘要

PURPOSE: To obtain a high strength UOE line pipe excellent in sulfide stress cracking resistance in the weld zone by specifying the compsn. constituted of C, Si, Mn, P, S, Nb, Al, Ca, Ti and Fe. ;CONSTITUTION: This line pipe has a compsn. contg., by weight, 0.03 to 0.09% C, 0.1 to 0.6% Si, 1.1 to 1.5% Mn, ≤0.015% P, ≤0.0010% S, 0.010 to 0.050% Nb, 0.005 to 0.03% Al, 0.002 to 0.004% Ca and 0.005 to 0.025% Ti and furthermore contg., at need, one or more kinds among 0.01 to 0.1% V, 0.1 to 1.0% Ni, 0.1 to 1.0% Cu, 0.1 to 1.0% Cr and 0.1 to 0.5% Mo, and the balance iron with inevitable impurities and also satisfying the inequalities: Ca(1-980)/S1.7 and 0.07Ca/Al0.17, and in which the form of oxides contg. Ca causing the generation of sulfide stress cracking is controlled, which sulfide stress cracking resistance is obtd. even in the softened zone.;COPYRIGHT: (C)1994,JPO