| 摘要 |
A martensitic stainless steel wherein the steel composition is limited with respect to specified components, wherein the Mo content is defined in relati on to IM value, and wherein the metallic structure thereof is mainly constitute d of tempered martensite, a carbide precipitated at tempering and intermetalli c compounds, Laves phase and .sigma.-phase, microprecipitated at tempering. Th is martensitic stainless steel has a high strength of 860 MPa or greater 0.2% proof stress and can exhibit excellent resistances to carbon dioxide gas corrosion and sulfide stress corrosion cracking. This martensitic stainless steel can be used as a highly practicable steel in a wide spectrum of fields , including oil well pipes, etc. exposed to an environment containing carbon dioxide gas, hydrogen sulfide, chloride ion or two or more of these.
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