Cold-rolled steel sheet
US7927433B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 27, 2010 |
| Grant date | Apr 19, 2011 |
| Priority date | — |
| Expiry date | Apr 27, 2030 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/009
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A cold-rolled steel sheet of carbon steel or low-alloy steel comprising C: 0.01 to 0.25% by mass with a ferrite main phase is has an average ferrite crystal grain diameter D (μm) at the depth of ¼ of the sheet thickness from the steel sheet surface satisfying formulas (5,6) and the increase rate X (μm/min) in average ferrite crystal grain diameter at 700° C. at the depth of ¼ of the sheet thickness from the steel sheet surface and D (μm) satisfying formula (3):1.2≦D≦9.3 (5)D≦5.0−2.0·Cr+5000/(5+350·C+40·Mn)2 (6)D·X≦0.1 (3)and, at said ¼ inch depth, the area percentage of ferrite crystal grains the crystal grain diameter d (μm) of which satisfying formula (4) is at least 80%:D/3≦d≦3D (4)wherein C, Cr and Mn represent mass % of the respective elements in the steel.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.