HIGH STRENGTH STAINLESS STEEL PIPING HAVING OUTSTANDING RESISTANCE TO SULPHIDE STRESS CRACKING AND RESISTANCE TO HIGH TEMPERATURE CARBON DIOXIDE CORROSION

摘要

The problem to be solved is the provision of a high-strength stainless steel pipe having a sufficient corrosion resistance in a high-temperature carbonic acid gas environment and having an excellent sulfide stress cracking resistance at normal temperature.;A high-strength stainless steel pipe consist 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: 1% 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 (1), and the balance being Fe and impurities; and the metal micro-structure of the stainless steel pipe mainly includes 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. $\[ \left[\mathrm{Mn}\right]\mathrm{\times }\left(\left[\mathrm{N}\right]\mathrm{-}\mathrm{0.0045}\right)\mathrm{\le }\mathrm{0.001} \]$wherein the symbols of elements in formula (1) respectively represent the contents (unit: mass%) of the elements in the steel.