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US 6,447,619 B1Granted
High surface pressure resistant steel parts and methods of producing same
AssigneeKomatsu Ltd.
InventorsTakemori Takayama, Naoji Hamasaka
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AssigneeKomatsu Ltd.
InventorsTakemori Takayama, Naoji Hamasaka
Estimating the term…
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 μm 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 μm 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 AlN, 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.
A method of producing a high surface pressure resistant steel part from a steel containing 0.3 to 3.0 wt % Al, 0.5 to 5.0 wt % Cr and 0.2 to 2.0 wt % V, the method comprising the steps of:
A method of producing a high surface pressure resistant steel part from a steel containing 0.3 to 3.0 wt % Al, 0.5 to 5.0 wt % Cr and 0.2 to 2.0 wt % V, wherein after allowing carbon to diffusely permeate from a surface by carburization, the steel is once cooled to a temperature equal to or less than the eutectoid transformation temperature;
Dependencies are inferred from the claim text.