High-strength, high-toughness stainless steel excellent in resistance to delayed fracture
US6679954B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 17, 2001 |
| Grant date | Jan 20, 2004 |
| Priority date | — |
| Expiry date | Aug 17, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The present invention makes the best use of a low-cost chemical composition in providing a high strength and high corrosion resistance stainless steel, which has improved delayed fracture resistance and toughness in particular, for building and construction uses, and as, for example, a stainless steel tapping screw. The present invention is, specifically, a stainless steel and a stainless steel screw with high strength and high toughness and excellent in delayed fracture resistance, characterized by: comprising, by mass, 0.01 to 0.25% of C, 0.05 to 1.0% of Si, 0.1 to 2.0% of Mn, 0.1 to 3.0% of Ni, 11.0 to 16.0% of Cr, 0.01 to 0.15% of N, and 0.01 to 3.0% of Mo; containing, optionally, 0.001 to 0.005% of B and/or one or more of 0.05 to 0.5% of Ti, 0.05 to 0.5% of Nb, and 0.05 to 0.5% of W; having less than 10% of ferrite in the center portion of the material; and having a mixed structure of martensite and 3 to 30% of austenite in the surface layer from the outermost surface to the depth of at least 1 &mgr;m, and a method to produce the same.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.