| 摘要 |
A martensitic stainless steel having a resistance to sulfide stress corrosion cracking superior to Super 13 Cr steel and having a strength and corrosion resistance comparable to dual phase stainless steels has a chemical composition consisting essentially of, in mass %, C: 0.001 - 0.1%, Si: 0.05 - 1.0%, Mn: 0.05 - 2.0%, P: at most 0.025%, S: at most 0.010%, Cr: 11 - 18%, Ni: 1.5 - 10%, sol. Al: 0.001 - 0.1%, N: at most 0.1%, O: at most 0.01%, Cu: 0 - 5%, solid solution Mo: 3.5 - 7%, the composition satisfying the following Equation (1), optionally at least one element selected from at least one of the following Groups A - C, and a remainder of Fe and impurities and undissolved Mo, if undissolved Mo is present. Equation €‰ ( 1 ) : Ni-bal . = 30 ( C + N ) + 0.5 ( Mn + Cu ) + Ni + 8.2 ˆ’ 1.1 ( Cr + Mo + 1.5 Si ) ‰¥ ˆ’ 4.5 Group A - W: 0.2 - 5% Group B - V: 0.001 - 0.50%, Nb: 0.001 - 0.50%, Ti: 0.001 - 0.50%, and Zr: 0.001 -0.50% Group C - Ca: 0.0005 - 0.05%, Mg: 0.0005 - 0.05%, REM: 0.0005 - 0.05%, and B: 0.0001 - 0.01% |
