Process for thermal treatment of metals
US5057164A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 26, 1990 |
| Grant date | Oct 15, 1991 |
| Priority date | — |
| Expiry date | Jun 26, 2010 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC21D1/76
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Process for thermal treatment of metals by passage of metallic pieces into an elongated zone under a controlled atmosphere, having an upstream section at an elevated temperature, where the controlled atmosphere comprises nitrogen and reductive chemicals, particularly hydrogen, possibly carbon monoxide; and a downstream section at a lower temperature under a controlled atmosphere. The invention is characterized by the fact that in the upstream section at an elevated temperature, the atmosphere comprises nitrogen having a residual content of oxygen between 0.5% and 5% produced by separation of air using permeation or adsorption techniques. The reductive chemicals are present at all times in a content at least sufficient to eliminate the oxygen admitted with the nitrogen. The controlled atmosphere in the section downstream from the elongated thermal treatment zone is formed by admission of a gaseous flow taken from the upstream section at an elevated temperature and transferred directly into the downstream section at a lower temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.