SEAMLESS STEEL PIPE FOR LINE PIPE USED IN SOUR ENVIRONMENT

摘要

There is provided a seamless steel pipe which is used in line pipe applications, which line pipe is used in sour environments, and is not subjected to quenching and tempering treatment, and in which the occurrence of blisters can be suppressed. The seamless steel pipe according to this embodiment has a chemical composition consisting, in mass% of, C: 0.08 to 0.24%, Si: 0.10 to 0.50%, Mn: 0.3 to 2.5%, P: 0.02% or less, S: 0.006% or less, Nb: 0.02 to 0.12%, Al: 0.005 to 0.100%, Ca: 0.0003 to 0.0050%, N: 0.0100% or less, O: 0.0050% or less, Ti: 0 to 0.1%, V: 0 to 0.03%, Cr: 0 to 0.6%, Mo: 0 to 0.3%, Ni: 0 to 0.4%, Cu: 0 to 0.3%, and B: 0 to 0.005%, the balance being Fe and impurities, has a structure consisting of ferrite and pearlite, and also has a yield strength of 350 to less than 450 MPa.