SEAMLESS STEEL PIPE FOR LINE PIPE AND METHOD FOR PRODUCING SAME

摘要

A seamless steel pipe for line pipe having high strength and stable toughness and having resistance to sulfide corrosion cracking at low temperatures to room temperature is provided. A seamless steel pipe according to the present invention has a chemical composition comprising, in mass percent, C: 0.03 - 0.08%, Si: 0.05 - 0.5%, Mn: 1.0 - 3.0%, Mo: greater than 0.4% to 1.2%, Al: 0.005 - 0.100%, Ca: 0.001 - 0.005%, a remainder of Fe and impurities including N, P, S, O, and Cu, with the impurities containing at most 0.01 % ofN, at most 0.05% of P, at most 0.01 % of S, at most 0.01 % of O, and at most 0.1 % of Cu, and having a microstructure comprising a bainitic-martensitic dual phase structure.