High-strength hot-rolled steel sheet and method for producing the same
US11603571B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 6, 2018 |
| Grant date | Mar 14, 2023 |
| Priority date | — |
| Expiry date | Jun 22, 2038 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
There are provided a high-strength hot-rolled steel sheet having a tensile strength of 980 MPa or more and a production method therefor. The high-strength hot-rolled steel sheet has a predetermined component composition and a microstructure containing 75.0% or more by area and less than 97.0% by area of a primary phase composed of an upper bainite phase, the primary phase having an average grain size of 12.0 μm or less, and more than 3.0% by area and 25.0% or less by area of a secondary phase that is a structure composed of one or two of a lower bainite phase and/or a tempered martensite phase, and a martensite phase, in which the number density of grains of the secondary phase having an equivalent circular diameter of 0.5 μm or more is 150,000 grains/mm2 or less, and the steel sheet has an arithmetic mean surface roughness of 2.00 μm or less.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.