High tensile strength steel sheet having improved formability
US5470529A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 8, 1994 |
| Grant date | Nov 28, 1995 |
| Priority date | — |
| Expiry date | Mar 8, 2014 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/005
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A high tensile strength, hot or cold rolled steel sheet having improved ductility and hole expandability consists essentially, on a weight basis, of: C: 0.05-0.3%, Si: 2.5% or less, Mn: 0.05-4%, Al: greater than 0.10% and not greater than 2.0% wherein 0.5.ltoreq.Si(%)+Al(%).ltoreq.3.0, optionally one or more of Cu, Ni, Cr, Ca, Zr, rare earth metals (REM), Nb, Ti, and V, and a balance of Fe and inevitable impurites with N being limited to 0.01% or less. The steel sheet has a structure comprising at least 5% by volume of retained austenite in ferrite or in ferrite and bainite. A hot rolled steel sheet is produced by hot rolling with a finish rolling end temperature in the range of 780.degree.-840.degree. C., cooling to a coiling temperature in the range of 300.degree.-450.degree. C. either by rapid cooling to the coiling temperature at a rate of 10.degree.-50.degree. C./sec or by initial rapid cooling to a temperature range of 600.degree.-700.degree. C., then air-cooling for 2-10 seconds, and final rapid cooling to the coiling temperature. A cold rolled steel sheet is produced by hot rolling, cooling to a coiling temperature in the range of 300.degree.-720.degree. C., descaling, cold…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.