High-strength steel sheet and manufacturing method therefor
US11186889B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 10, 2017 |
| Grant date | Nov 30, 2021 |
| Priority date | — |
| Expiry date | Feb 23, 2039 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A high-strength steel sheet contains, in mass %, C: 0.07 to 0.14%, Si: 0.65 to 1.65%, Mn: 1.8 to 2.6%, P: 0.05% or less, S: 0.005% or less, Al: 0.08% or less, N: 0.0060% or less, Ti: 0.005 to 0.030%, B: 0.0002 to 0.0030%, and either or both of Cr: 0.01 to 0.40% and Mo: 0.01 to 0.50% and satisfies the expression (1); where: an average grain size of a ferrite phase is 1.5 μm or less; an area ratio of the ferrite phase is 2% or more and 15% or less; an area ratio of a tempered martensite phase is 75% or more and 96% or less; and a total length per unit area of an interface between an untempered martensite phase and the ferrite phase and an interface between the untempered martensite phase and the tempered martensite phase is 6.3×108 μm/m2 to 5.0×1011 μm/m2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.