Method for producing a formed steel part having a predominantly ferritic-bainitic structure
US8888934B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 24, 2009 |
| Grant date | Nov 18, 2014 |
| Priority date | — |
| Expiry date | Apr 24, 2029 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D2211/005
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
In a method to produce formed steel parts a primary steel material is provided, which (in % by weight) comprises C: 0.02-0.6%, Mn: 0.5-2.0%, Al: 0.01-0.06%, Si: max. 0.4%, Cr: max. 1.2%, P: max. 0.035%, S: max. 0.035%, and optionally one or more of the elements of the “Ti, Cu, B, Mo, Ni, N” group, with the proviso that Ti: max. 0.05%, Cu: max. 0.01%, B: 0.0008-0.005%, Mo: max. 0.3%, Ni: max. 0.4%, N: max. 0.01%, and the remainder as iron and unavoidable impurities. The primary material is heated through at a heating temperature (TA) lying between the Ac1 and the Ac3 temperature, such that at best incomplete austenitising of the primary material takes place, is placed into a press-form tool and formed therein into the formed steel part. The formed steel part is then heated to a bainite forming temperature (TB), which is above the martensite starting temperature (MS), however below the pearlite transformation temperature of the steel. After cooling, it is maintained for an austernpering period (tB) at the bainite forming temperature (TB) in a substantially isothermic manner, until the foamed steel part has produced a structure consisting predominantly of ferrite and bainite, the mart…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.