| 摘要 |
PROBLEM TO BE SOLVED: To provide a martensitic Cr-containing steel material which can achieve a yield strength of 517 MPa or less by being subjected to low-temperature and brief tempering, and has resistance to COcorrosion and resistance to sulfide stress cracking in a corrosive environment containing CO, HS, Cl, and the like.SOLUTION: The martensitic Cr-containing steel material has a chemical composition which contains C≤0.01%, Si: 0.05 to 1.0%, Mn: 0.01 to less than 3.0%, Cr: more than 9.0% and 12.0% or less, sol.Al: more than 0.005% and 0.05% or less, Nb: more than 0.01% and 0.2% or less and [Nb-7.735×C-6.63×N]≥0.01%, Cu: 0 to 3.0%, and the remainder: Fe and impurities, and in which [-477.0×C+11.6×Si-19.7×Mn+23.0×Cr+40.4×Nb+79.8×V+132.4×sol.Al-32.8×Ni-269.5×N]<240, and the impurities contains P≤0.03%, S≤0.003%, Ni≤0.3%, V≤0.05%, N≤0.01%, and O≤0.01%. The steel material has a yield strength of 517 MPa or less. |
