Ultra-high strength ausaged steels with excellent cryogenic temperature toughness
US6251198A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 18, 1998 |
| Grant date | Jun 26, 2001 |
| Priority date | — |
| Expiry date | Jun 18, 2018 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/008
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
An ultra-high strength, weldable, low alloy steel with excellent cryogenic temperature toughness in the base plate and in the heat affected zone (HAZE) when welded, having a tensile strength greater than 830 MAP (120 KS) and a micro-laminate microstructure comprising austenite film layers and fine-grained marten site/lower bainite laths, 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; finish rolling the plate in one or more passes in a temperature range below the austenite recrystallization temperature and above the Ar.sub.3 transformation temperature; quenching the finish rolled plate to a suitable Quench Stop Temperature (QST); stopping the quenching; and either, for a period of time, holding the plate substantially isothermally at the QST or slow-cooling the plate before air cooling, or simply air cooling the plate to ambient temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.