| 摘要 |
Disclosed is a high-strength seamless steel pipe, which has excellent sulfide stress cracking resistance (SSC resistance), for use in oil wells. Specifically the seamless steel pipe has a composition containing, by mass %: C: 0.15-0.50%, Si: 0.1-1.0%, Mn: 0.3-1.0%, P: 0.015% or less, S: 0.005% or less, Al: 0.01-0.1% or less, N: 0.01% or less, Cr: 0.1-1.7%, Mo: 0.40-1.1%, V: 0.01-0.08%, Nb: 0.01-0.08%, B: 0.0005-0.003% and optionally Cu: 0.03-1.0%; where 0.40% or more of solute Mo is included within the aforementioned Mo; and a composition formed by the dispersal of 0.06 mass % or more of roughly particulate M<sub>2</sub>C precipitates, which has a tempered martensite main phase and has prior austenite grains with a grain number of 8.5 or greater. |
