Steel sheet with strain induced transformation type composite structure and method of manufacturing same
US10689724B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 31, 2015 |
| Grant date | Jun 23, 2020 |
| Priority date | — |
| Expiry date | Dec 1, 2035 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
There is provided a steel sheet with strain induced transformation type composite structure having a predetermined chemical composition in which a microstructure at the ¼ thickness of the steel sheet includes, by area ratio, 50% to 85% of a polygonal ferrite, 3% to 10% of a residual austenite, 5% to 47% of bainite and 1% or less of a fresh martensite and a tempered martensite in total and satisfies the equation of 0.01<Ex.C/fsd≤0.015, the microstructure includes 1×1016 pieces/cm3 or more of precipitates containing TiC, an average grain diameter of the residual austenite 1.0 μm to 5.0 μm at an equivalent circle diameter, an average of closest distances of the austenite is 3.0 μm to 10.0 μm, and an average diameter of the precipitates is 3 nm or less.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.