| 摘要 |
PURPOSE:To produce a seam welded steel pipe having the excellent stress corrosion cracking resistance in the weld zone by subjecting the seam part of the seam welded steel pipe consisting of specifically composed C, Si, Mn, P, S, Nb, V, Ti and Fe to a stress relief treatment under adequate conditions. CONSTITUTION:The seam part of the seam welded steel pipe consisting essentially of 0.03-0.22% C, <=0.5% Si, 1.0-2.0% Mn, <=0.009% P and <=0.005% S, contg. >=1 kinds among <=0.050% Nb, <=0.050% V and <=0.030% Ti and consisting of the balance Fe and unavoidable impurities is heated to 920-1,050 deg.C and is then air cooled. The seam part is then subjected to the stress relief treatment at 400-730 deg.C. The sour resistance characteristic of the seam welded part is thereby improved to about the same level as the characteristic of the base metal part and the seam welded pipe having the excellent stress corrosion cracking resistance in the seam welded part is obtd.
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