초록 ▼

High surface pressure resistant steel parts and their producing methods are disclosed. These steel parts are useful as gears, cams, bearings and similar high-strength compact steel articles which are required to have wear resistance and strength to withstand fatigue in rolling or rolling-slipping ap

High surface pressure resistant steel parts and their producing methods are disclosed. These steel parts are useful as gears, cams, bearings and similar high-strength compact steel articles which are required to have wear resistance and strength to withstand fatigue in rolling or rolling-slipping applications. In a steel part formed according to the invention, a fine nitride and/or carbonitride having at least an average grain size of 0.3 .mu.m or less is dispersed in the contact surface structure; a multi phase structure composed of martensite, which is divided into extremely fine pieces, forming a disordered shape, by the nitride and/or carbonitride, is formed; and a carbide having a grain size of 3 .mu.m or less is dispersed to increase the hardness of the surface. Such a steel part is produced by carrying out carbonitriding or carburization/carbonitriding so as to precipitate extremely fine AIN, using nitrogen permeating from the surface and by carrying out quenching or quenching/tempering, starting from a temperature region where the parent phase is austenite

대표청구항 ▼

1. A high surface pressure resistant steel part containing a fine nitride and/or carbonitride which is dispersed only in a surface structure extending from the surface to a depth of 1 mm below the surface having an average grain size of 0.3 .mu.m or less in an amount of 1% by volume or more and cont

1. A high surface pressure resistant steel part containing a fine nitride and/or carbonitride which is dispersed only in a surface structure extending from the surface to a depth of 1 mm below the surface having an average grain size of 0.3 .mu.m or less in an amount of 1% by volume or more and containing a carbide mainly composed of cementite having an average grain size of 3 .mu.m or less which is dispersed in an amount up to 30% by volume and having a multi phase structure composed of martensite as a parent phase which is finely divided into pieces by said dispersed substance and further containing 20 to 80% by volume residual austenite in said multi phase structure and containing 1.1 wt. % or more carbon in its surface.