Process for heat treating metals in a continuous oven under controlled atmosphere

US5069728A · kind A · utility

Assignee

• L'Air Liquide, Societe Anonyme Pour l'Etude et l'Exploitation des Procedes Georges Claude · FR

Inventors

• Yannick Rancon · Auxerre, FR
• Eric Duchateau · Versailles, FR

Key dates

• Filing date: Jun 26, 1990
• Grant date: Dec 3, 1991
• Expiry date: Jun 26, 2010

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C22F1/02
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

Heat treating metals by continuous longitudinal passage of metallic pieces in an elongated treating zone under controlled atmosphere having a high temperature upstream end where the controlled atmosphere comprises nitrogen and reducing chemical substances, such as hydrogen, possibly carbon monoxide, and a downstream cooling end under an atmosphere essentially formed by introducing nitrogen. In the high temperature upstream end, the nitrogen which constitutes the atmosphere is supplied by introducing nitrogen with a residual oxygen content not exceeding 5%, the reducing chemical substances being present at any moment in amounts at least sufficient to eliminate oxygen introduced with nitrogen. The nitrogen introduced in the downstream cooling end is substantially free of oxygen. Application of the process to the annealing of metallic pieces.