Cold-rolled steel sheet and method of manufacturing same
US10876181B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 24, 2016 |
| Grant date | Dec 29, 2020 |
| Priority date | — |
| Expiry date | Nov 24, 2037 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22C38/60
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
In a cold-rolled steel sheet having a predetermined chemical composition, a metallographic structure contains 40.0% or more and less than 60.0% of a polygonal ferrite, 30.0% or more of a bainitic ferrite, 10.0% to 25.0% of a residual austenite, and 15.0% or less of a martensite, by an area ratio, in the residual austenite, a proportion of the residual austenite in which an aspect ratio is 2.0 or less, a length of a long axis is 1.0 μm or less, and a length of a short axis is 1.0 μm or less, is 80.0% or more, in the bainitic ferrite, a proportion of the bainitic ferrite in which an aspect ratio is 1.7 or less and an average value of a crystal orientation difference in a region surrounded by a boundary in which a crystal orientation difference is 15° or more is 0.5° or more and less than 3.0°, is 80.0% or more, and a connection index D value of the martensite, the bainitic ferrite, and the residual austenite is 0.70 or less.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.