Method of carburizing workpiece

US4519853A · kind A · utility

Assignee

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

Inventors

• Michel Kostelitz · Versailles, FR
• Philippe Queille · Paris, FR

Key dates

• Filing date: May 23, 1983
• Grant date: May 28, 1985
• Expiry date: May 23, 2003

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C23C8/22
• WIPO field: Surface technology, coating
• WIPO sector: Chemistry

Abstract

The method of carburizing steel workpieces comprises loading workpieces to be carburized in a furnace and maintaining them in a carbon enriching atmosphere comprising carbon monoxide, hydrogen and nitrogen. The treatment comprises a first phase carried out at a temperature from 850.degree. C. to 1050.degree. C. followed by a second phase carried out at a temperature from 700.degree. C. to 950.degree. C. During the first phase an atmosphere is used having a carbon potential from about 1.1% to about 1.6% by weight and during the second phase the amount of nitrogen in the atmosphere is increased from two to thirty times so that the carbon potential for the second phase is at least about 0.5% by weight less than the carbon potential for the first phase.