| 摘要 |
PROBLEM TO BE SOLVED: To provide a thick electric resistance welded pipe having excellent strength and low temperature toughness in the base metal part and the electric resistance weld zone required as those of a high-pressure line pipe for cold districts, and to provide its production method. SOLUTION: The thick electric resistance welded pipe having excellent toughness in the base metal part and the electric resistance weld zone has a composition comprising, by mass, 0.03 to 0.10% C, 0.05 to 0.50% Si, 0.5 to 2.0% Mn≤0.030% P,≤0.010% S,≤0.010% N, 0.001 to 0.10% Al, 0.001 to 0.5% Cr, 0.001 to 0.10% Nb, 0.001 to 0.10% V and 0.001 to 0.10% Ti, further comprising one or more selected from 0.01 to 0.50% Cu, 0.01 to 0.50% Ni and 0.01 to 0.50% Mo, and the balance Fe with inevitable impurities, and in which Pcm is controlled to≤0.17, the ratio of bainitic ferrite in the base metal structure is≥95vol.%, the precipitation fraction of the second phase in the electric resistance weld zone is≤30vol.%, and the old austenite grain size is≤100μm. COPYRIGHT: (C)2008,JPO&INPIT |
