Stainless steel for oil well, stainless steel pipe for oil well, and method of manufacturing stainless steel for oil well
US9109268B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 19, 2011 |
| Grant date | Aug 18, 2015 |
| Priority date | — |
| Expiry date | Oct 19, 2031 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The chemical composition of a stainless steel in accordance with the present invention consists of C: not more than 0.05%, Si: not more than 0.5%, Mn: 0.01 to 0.5%, P: not more than 0.04%, S: not more than 0.01%, Cr: more than 16.0 and not more than 18.0%, Ni: more than 4.0 and not more than 5.6%, Mo: 1.6 to 4.0%, Cu: 1.5 to 3.0%, Al: 0.001 to 0.10%, and N: not more than 0.050%, the balance being Fe and impurities, and satisfies Formulas (1) and (2). Also, the micro-structure thereof contains a martensitic phase and a ferritic phase having a volume ratio of 10 to 40%, and the ferritic phase distribution ratio is higher than 85%.Cr+Cu+Ni+Mo≧25.5 (1)−8≦30(C+N)+0.5Mn+Ni+Cu/2+8.2−1.1(Cr+Mo)≦−4 (2)
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.