| 摘要 |
PROBLEM TO BE SOLVED: To produce a high strength steel pipe excellent in SR resistance, in which the toughness before and after SR in the weld zone including a base metal and a weld metal is excellent, and yield strength is >=551 MPa. SOLUTION: This high strength steel pipe excellent in SR resistance, which has a base metal part having a composition containing 0.03 to 0.09% C, 0.05 to 0.40% Si, 1.2 to 2.0% Mn, <=0.020% P, <=0.002% S, 0.005 to 0.05% Nb, 0.005 to 0.02% Ti and 0.01 to 0.04% Al, and the balance substantial iron and having yield strength of >=551 MPa, and a weld metal having a composition containing 0.03 to 0.12% C, 0.05 to 0.30% Si, 1.2 to 2.0% Mn, <=0.020% P, <=0.005% S, 0.5 to 2.5% Ni and 0.3 to 1.0% Mo and also containing one or two or more kinds among <=0.50% Cu, <=1.0% Cr and <=0.10% V, and the balance substantial iron and having yield strength of >=551 MPa, is used.
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