Spring steel and spring superior in fatigue properties
US8900381B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 30, 2008 |
| Grant date | Dec 2, 2014 |
| Priority date | — |
| Expiry date | Oct 4, 2030 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/004
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Disclosed is a spring steel which contains, by mass, 1.2% or less C; 0.1% to 2% Mn; 0.2% to 3% Si; 0.0003% to 0.005% Al; to 8 ppm Li; 30 ppm or less (excluding 0 ppm) Ca; and 10 ppm or less (excluding 0 ppm) Mg. The steel contains oxide inclusions satisfying the following conditions (1) to (3) in a number of 1×10−4 or more per square millimeter: (1) containing a total of 80 percent by mass or more of Al2O3 and SiO2 based on the inclusion composition excluding Li2O; (2) having a ratio by mass of Al2O3 to SiO2 of from 1:4 to 2:3; and (3) containing lithium (Li). The spring steel gives a spring that exhibits superior fatigue properties without strict control of the average composition of inclusions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.