METHOD FOR PRODUCING NITRIDING STEEL

Title:

METHOD FOR PRODUCING NITRIDING STEEL

Document Type and Number:

WIPO Patent Application WO/2003/033757

Kind Code:

A1

Abstract:

A method for producing a nitriding steel, characterized in that it comprises subjecting a steel to a nitriding treatment, and subsequently, to a passivation treatment wherein the nitrided steel is heated in an atmosphere containing oxygen. The condition of the heating for the passivation treatment is preferably set within a range surrounded by the following points on the axis of coordinates of temperature and time: (100&ring C, 120 min), (100&ring C, 10 min), (125&ring C, 5 min), (190&ring C, 5 min), (200&ring C, 10 min), (200&ring C, 20 min), (190&ring C, 30 min), (190&ring C, 40 min), (180&ring C, 60 min), (180&ring C, 120 min). The method allows the formation of a uniform passivating film in a simple and easy way, which film provides a nitriding steel exhibiting improved resistance to pitting corrosion and, associated therewith, improved fatigue strength.

Inventors:

ISHII KAZUO (JP)
ODAGIRI YOSHIHIRO (JP)
MUNEMURA TAKESHI (JP)

Application Number:

PCT/JP2002/007395

Publication Date:

April 24, 2003

Filing Date:

July 22, 2002

Export Citation:

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Assignee:

HONDA MOTOR CO LTD (JP)
ISHII KAZUO (JP)
ODAGIRI YOSHIHIRO (JP)
MUNEMURA TAKESHI (JP)

International Classes:

C21D1/06; C23C8/26; C22C38/00; C22C38/14; C23C8/14; C23C8/32; C23C8/34; (IPC1-7): C23C8/34

Foreign References:

JPS6479362A	1989-03-24
EP0299625A2	1989-01-18
EP0217420A2	1987-04-08

Other References: