Carbonitriding method having a final nitridation step during temperature decrease
US9938615B2 · kind B2 · utility
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9Claims
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Key dates
| Filing date | Oct 8, 2012 |
| Grant date | Apr 10, 2018 |
| Priority date | — |
| Expiry date | Oct 29, 2033 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23C8/80
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A method for the low-pressure carbonitriding of steel parts, in particular parts used in the manufacture of automobiles comprises a heating step that includes a simple heating phase (M) followed by an initial nitridation phase (Ni) from a temperature between 700° C. to 750° C. to a temperature between 860° and 1000° C. carried out using a reduced temperature gradient relative to the simple heating phase. The method further includes alternate cementing (C1-Cn) and nitridation (N1-Nn) steps at constant temperature, wherein the final nitridation step is accompanied with a decrease in temperature immediately before quenching (T).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.