| 摘要 |
Provided is a high alloy for oil well use, having high strength and exceptional hot workability and SCC resistance. This high alloy for oil well use contains, expressed in mass%, C: 0.03% or less, Si: 1.0% or less, Mn: 0.05-1.5%, P: 0.03% or less, S: 0.03% or less, Ni: 26.0-40.0%, Cr: 22.0-30.0%, Mo: at least 0.01% but less than 5.0%, Cu: 0.1-3.0%, Al: 0.001-0.30%, N: more than 0.05% but not more than 0.30%, O: 0.010% or less, Ag: 0.005-1.0%, Ca: 0-0.01%, Mg: 0-0.01%, and rare earth elements: 0-0.2%, with the remainder comprising Fe and impurities. The alloy satisfies the following expression (1) and expression (2), and has yield strength of 758 MPa or above. 5 × Cu + (1,000 × Ag) 2 ≧ 40 (1) Cu + 6 × Ag - 500 × (Ca + Mg + REM) ≦ 3.5 (2) Here, the contained amounts (in mass%) are substituted for the element symbols in the expressions. |
