High strength hot-rolled steel sheet and method for manufacturing the same
US9284618B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 23, 2011 |
| Grant date | Mar 15, 2016 |
| Priority date | — |
| Expiry date | Apr 21, 2033 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/003
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A high strength hot-rolled steel sheet with a tensile strength of not less than 590 MPa which exhibits excellent bake hardenability and stretch-flangeability has a chemical composition including, in terms of mass %, C at 0.040 to 0.10%, Si at not more than 0.3%, Mn at 1.7 to 2.5%, P at not more than 0.030%, S at not more than 0.005%, Al at not more than 0.1% and N at 0.006 to 0.025%, and microstructure wherein a bainite phase represents not less than 60%, the total of a ferrite phase and a pearlite phase represents not more than 10%, and the bainite phase includes grains among which cementite grains have been precipitated at not less than 1.4×104 grains/mm2 and the cementite grains have an average grain diameter of not more than 1.5 μm.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.