Bearing pressure-resistant member and process for making the same

a technology of pressure-resistant components and pressure-resistant components, which is applied in the direction of solid-state diffusion coatings, mechanical devices, coatings, etc., can solve the problems of difficult homogeneous dispersing of msub>, excessive long treatment time at the holding step, and deterioration of rolling fatigue strength, so as to improve significantly surface fatigue strength and reduce residual h2. , the effect of excellent surface fatigue strength

US20050045249A1Inactive Publication Date: 2005-03-03NISSAN MOTOR CO LTD
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
Publication Date
2005-03-03
Estimated Expiration
Not applicable · inactive patent

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Abstract

A bearing pressure-resistant member, including a matrix and a carbide dispersed in the matrix, the carbide having an average particle size of not more than 0.3 μm. A carbon (C) content in an outer surface of the bearing pressure-resistant member is in a range of 0.6 to 1.5 mass percent. A process for making the bearing pressure-resistant member including subjecting a workpiece containing C to either of gas carburizing and gas carbonitriding to enhance the C content in the outer surface of the workpiece to 0.6 to 1.5 mass percent, holding the workpiece at a first temperature not more than an Ac1 transformation point under reduced pressure, heating the workpiece to a second temperature not less than the Ac1 transformation point under reduced pressure, followed by holding the workpiece at the second temperature, and subjecting the workpiece to quenching.
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Description

BACKGROUND OF THE INVENTION The present invention relates to an element useable as a power transmission part such as gears and rolling-contact bearings, which necessitates a high surface fatigue strength. More specifically, this invention relates to a bearing pressure-resistant member suitable for use under a relatively high bearing pressure in a relatively high temperature range of about 100° C. to about 300° C., and relates to a process for making the bearing pressure-resistant member. There have been proposed methods for enhancing bearing pressure strength of the above-described power transmission part. Among the methods, there are hyper-eutectoid carburizing and high density carburizing. In these carburizing methods, M3C carbide such as Fe3C which is not readily decomposed in the above-described temperature range, is precipitated so that hardness of the part and resistance to tempering softening can be enhanced. European Patent Application Publication No. 1070760 A2 (correspon...

Examples

examples

The present invention is described in more detail by way of examples and comparative examples by referring to the accompanying drawings. However, these examples are only illustrative and not intended to limit a scope of the present invention thereto.