Cryogenic treatment of martensitic steel with mixed hardening
US10174391B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 2, 2010 |
| Grant date | Jan 8, 2019 |
| Priority date | — |
| Expiry date | Mar 21, 2032 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22C38/52
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The invention relates to a method for producing martensitic steel that comprises a content of other metals such that the steel can be hardened by an intermetallic compound and carbide precipitation, with an Al content of between 0.4% and 3%, comprising the following steps: The temperature T1 is substantially lower than the martensitic transformation temperature Mf, and the time t during which said steel is kept in said cryogenic medium at a temperature T1 from the moment when the hottest part of the steel reaches a temperature lower than the martensitic transformation temperature Mf is at least equal to a non-zero time t1, the temperature T1 (in ° C.) and the time t1 (in hours) being linked by the equation T1=ƒ(t1), the first derivative of the function ƒ relative to t, ƒ′(t), being positive, and the second derivative of ƒ relative to t, ƒ″(t), being negative.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.