Hot-pressed member and method for manufacturing same, and cold-rolled steel sheet for hot pressing and method for manufacturing same
US11111558B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 30, 2018 |
| Grant date | Sep 7, 2021 |
| Priority date | — |
| Expiry date | May 25, 2038 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC25D7/0614
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Disclosed is a hot-pressed member that can exhibit very high tensile strength after hot pressing as high as TS: 1780 MPa or more, and excellent resistance to resistance welding cracking by properly adjusting its chemical composition and its microstructure such that a prior austenite average grain size is 7.5 μm or less, a volume fraction of martensite is 95% or more, and at least 10 Nb-based and Ti-based precipitates having a grain size of less than 0.10 μm are present on average per 100 μm2 of a cross section parallel to a thickness direction of the member within a range of 100 μm or less in the thickness direction from the surface of the member, and such that a B concentration in prior austenite grain boundaries is at least 3.0 times a B concentration at a position 5 nm away from the grain boundaries.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.