Steel for suspension spring and method of manufacturing same
US10752969B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 10, 2016 |
| Grant date | Aug 25, 2020 |
| Priority date | — |
| Expiry date | Oct 7, 2036 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16F1/02
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Steel for a suspension spring including, as a chemical composition, by % by mass: C: more than 0.40% and 0.65% or less; Si: 1.00% to 3.50%; Mn: more than 2.00% and 3.00% or less; Cr: 0.01% to 2.00%; V: 0.02% to 0.50%; P: 0.020% or less; S: 0.020% or less: N: 0.0100% or less; and a remainder of Fe and impurities, in which Kf is 280 or more, in which a structure contains a tempered martensite of which an area ratio is 90% or more, in which a Fe-based carbide precipitated in the tempered martensite is a cementite, and in which an average of an area ratios of prior austenite grains which stretch in a longitudinal direction of the steel and of which an aspect ratio exceeds 3.0, is 80% or more in a case of depths of 0.1 mm, 0.2 mm, and 0.3 mm in a sheet thickness direction from a surface of the steel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.