Method of austempering steel parts

US6843867B1 · kind B1 · utility

Assignee

• Robert Bosch GmbH · DE

Inventors

• Lothar Foerster · Stuttgart, DE
• Michael Francis Michalski · Simpsonville, US
• Andreas Becht · Ludwigsburg, DE
• Karl-Otto Englert · Gundelsheim, DE
• Michael Czeringer · Ditzingen, DE

Key dates

• Filing date: Oct 18, 2000
• Grant date: Jan 18, 2005
• Expiry date: Apr 18, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C21D2211/002
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A method of austempering of steel parts is described. The steel parts are initially austenitized and subsequently quenched to a start temperature which is higher than the martensite start temperature. Then the steel parts are subjected to a first isothermal holding at the start temperature for a first time period. Subsequently the steel parts are held for a second isothermal time period at a finish temperature which is higher than the start temperature. The method described is particularly well suited for rapid austempering of steel parts, a pure bainitic structure being achievable, and the core hardness of the steel parts obtained being settable via the start temperature, the finish temperature, the duration of the first time period, and the duration of the second time period.