Patent ID: 8608872

Claim:
A high-strength stainless steel pipe excellent in sulfide stress cracking resistance and high-temperature carbonic-acid gas corrosion resistance and having a yield strength of 758 MPa or more, characterized in that: the stainless steel pipe consists of, by mass %, C: 0.05% or less, Si: 1.0% or less, P: 0.05% or less, S: less than 0.002%, Cr: more than 16% and 18% or less, Mo: more than 2% and 3% or less, Cu: 2.2% to 3.5%, Ni: 3% or more and less than 5%, Al: 0.001% to 0.1% and O: 0.01% or less, Mn: 1% or less and N: 0.05% or less, and Mn and N in the above ranges satisfy formula (I), and the balance being Fe and impurities; and the metal micro-structure of the stainless steel pipe mainly comprises a martensitic phase and comprises 10 to 40% of a ferritic phase by volume fraction and 10% or less of a retained γ-phase by volume fraction; and [Mn]×([N]−0.0045)≦0.001 (1) wherein the symbols of elements respectively represent the contents (unit: mass %) of the elements in the steel.