Method for manufacturing an ultra soft high carbon hot-rolled steel sheet
US7909950B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 19, 2006 |
| Grant date | Mar 22, 2011 |
| Priority date | — |
| Expiry date | Jan 31, 2028 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D6/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The present invention provides an ultra soft high carbon hot-rolled steel sheet. The ultra soft high carbon hot-rolled steel sheet contains 0.2% to 0.7% of C, 0.01% to 1.0% of Si, 0.1% to 1.0% of Mn, 0.03% or less of P, 0.035% or less of S, 0.08% or less of Al, 0.01% or less of N, and the balance being Fe and incidental impurities and further contains 0.0010% to 0.0050% of B and 0.05% to 0.30% of Cr in some cases. In the texture of the steel sheet, an average ferrite grain diameter is 20 μm or more, a volume ratio of ferrite grains having a grain diameter of 10 μm or more is 80% or more, and an average carbide grain diameter is in the range of 0.10 to less than 2.0 μm. In addition, the steel sheet is manufactured by the steps, after rough rolling, performing finish rolling at a reduction ratio of 10% or more and at a finish temperature of (Ar3−20° C.) or more in a final pass, then performing first cooling within 2 seconds after the finish rolling to a cooling stop temperature of 600° C. or less at a cooling rate of more than 120° C./sec, then performing second cooling so that the steel thus processed is held at 600° C. or less, then performing coiling at 580° C. or less, followed b…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.