Martensitic stainless steel and method for manufacturing same
US7662244B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 23, 2003 |
| Grant date | Feb 16, 2010 |
| Priority date | — |
| Expiry date | Jul 8, 2023 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A martensitic stainless steel provided includes C: 0.01-0.1% and Cr: 9-15%, and the retained austenite phase has a thickness not more than 100 nm in such a manner that the X-ray integral intensities of 111γ and 110α satisfy the following formula (a):0.005≦111γ/(111γ+110α)≦0.05 (a)Such a metal structure can be obtained by the following procedure: the steel is heated at a temperature of the Ac3 point or more, and then cooled from 800° C. to 400° C. at a cooling rate of not less than 0.08° C./sec and further cooled down to 150° C. at a cooling rate of not more than 1° C./sec. The martensitic stainless steel according to the present invention has a relatively high carbon content and a greater toughness in spite of a high mechanical strength, and further exhibits an excellent corrosion resistance, so that it is particularly effective as the material for constructing a deep oil well.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.