High-strength stainless seamless steel pipe for oil wells and method for producing the same

Abstract

Provided are a high-strength stainless seamless steel pipe for oil wells and a method for producing the same. The steel pipe has a chemical composition containing, by mass, C: 0.002% to 0.05%, Si: 0.05% to 0.50%, Mn: 0.04% to 1.80%, P: 0.030% or less, S: 0.0020% or less, Cr: more than 14.0% and 17.0% or less, Ni: 4.0% to 8.0%, Mo: 1.5% to 3.0%, Al: 0.005% to 0.10%, V: 0.005% to 0.20%, N: 0.002% to 0.15%, Ti: 0.002% to 0.020%, and O: 0.006% or less, the Cr, Ni, Mo, Cu, C, Si, Mn, and N satisfying predetermined relational expressions. The microstructure of the steel pipe includes a martensite phase with an area fraction of 70% or more. The average Ti concentration in inclusions having a major-axis length of 2 μm or more is 10% by mass or more. The steel pipe has a yield strength of 758 MPa or more.