Steel sheet and manufacturing method of therefor
US11447848B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 30, 2018 |
| Grant date | Sep 20, 2022 |
| Priority date | — |
| Expiry date | Jun 8, 2038 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC25D5/36
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A steel sheet wherein a steel structure of an inside of the steel sheet contains, by volume fraction, soft ferrite: 0% to 30%, retained austenite: 3% to 40%, fresh martensite: 0% to 30%, a sum of pearlite and cementite: 0% to 10%, and a remainder including hard ferrite. In the steel sheet, in a ⅛ to ⅜ thickness range, a proportion of retained austenite having an aspect ratio of 2.0 or more is 50% or more, and a soft layer having a thickness of 1 to 100 μm from a surface in a sheet thickness direction is present. When an emission intensity at a wavelength indicating Si is analyzed in the sheet thickness direction from the surface by a radio-frequency glow discharge analysis method, a peak of the emission intensity appears in a range of more than 0.2 μm and 5.0 μm or less from the surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.