ELECTROSEAMED STEEL PIPE SUPERIOR IN SOUR RESISTANCE AT ELECTROSEAMED WELD PART FOR HIGH-STRENGTH THICK-WALL LINE PIPE

摘要

PROBLEM TO BE SOLVED: To provide an electroseamed steel pipe having improved sour resistance at an electroseamed weld part for a high-strength thick-wall line pipe.;SOLUTION: In the electroseamed steel pipe superior in sour resistance at the electroseamed weld part for the high-strength thick-wall line pipe, the electroseamed weld part is limited such that an area rate of the oxides is 20% or lower; the maximum length of the long side in welded seam side is 50 μm or less; thickness in the direction perpendicular to the welded seam side is 3 μm or less, and an aspect ratio is 5 or more, which is the ratio of the maximum length of the long side to the thickness. The chemical compositions of the electroseamed weld part the base metal part are also regulated.;COPYRIGHT: (C)2011,JPO&INPIT