Ultra-high strength triple phase steels with excellent cryogenic temperature toughness
US6159312A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 1998 |
| Grant date | Dec 12, 2000 |
| Priority date | — |
| Expiry date | Dec 19, 2018 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
An ultra-high strength, weldable, low alloy, triple phase steel with excellent cryogenic temperature toughness in the base plate and in the heat affected zone (HAZ) when welded, having a tensile strength greater than about 830 MPa (120 ksi) and a microstructure comprising a ferrite phase, a second phase of predominantly lath martensite and lower bainite, and a retained austenite phase, is prepared by heating a steel slab comprising iron and specified weight percentages of some or all of the additives carbon, manganese, nickel, nitrogen, copper, chromium, molybdenum, silicon, niobium, vanadium, titanium, aluminum, and boron; reducing the slab to form plate in one or more passes in a temperature range in which austenite recrystallizes; further reducing the plate in one or more passes in a temperature range below the austenite recrystallization temperature and above the Ar.sub.3 transformation temperature; finish rolling the plate between the Ar.sub.3 transformation temperature and the Ar.sub.1 transformation temperature; quenching the finish rolled plate to a suitable Quench Stop Temperature (QST); and stopping the quenching.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.