Patent ID: 7842141

Claim:
A corrosion-resistant seamless stainless steel pipe for oil country tubular goods having a steel composition comprising on a mass basis: 0.05% or less of C; 0.50% or less of Si; 0.20% to 1.80% of Mn; 0.03 or less of P; 0.005% or less of S; 14.0% to 18.0% of Cr; 5.0% to 8.0% of Ni; 1.5% to 3.5% of Mo; 0.5% to 3.5% of Cu; 0.05% or less of Al; 0.03% to 0.20% of V; 0.01% to 0.15% of N; 0.006% or less of O, and the balance being Fe and incidental impurities, wherein the composition satisfies expressions (1) and (2): Cr+0.65Ni+0.6Mo+0.55Cu+20C≧18.5 (1); Cr+Mo+0.3Si−43.5C−0.4Mn−Ni−0.3Cu−9N≦11 (2), where Cr, Ni, Mo, Cu, C, Si, Mn, and N represent the respective contents thereof on a mass % basis, and the structure of the stainless steel pipe includes 5 to 25 percent by volume of a residual austenite phase and the balance being a martensite phase.