General Electric Company

Michael Gilbert Johnson

Kenneth Lee Fisher

Jerry Donald Schell

Mark Alan Rhoads

Michael J Price

Jonothan Allen Scheetz

Alexander H Nahm

Russell R Carter

A roller bearing that provides ball and roller bearing elements comprised of M50 steel and M50NiL steel having surface hardnesses above 60 HRC, and in the range of 65-72 HRC. The hardness in the surface region is achieved by nitriding the surface to achieve a high hardness and extended life. This improvement is brought about by controlling the microstructure of the alloy by minimizing the formation of retained austenite. The material is tempered as required. The surface is then nitrided, but the nitriding operation is carefully controlled to avoid the formation of intergranular nitrides. Because of the method used to prevent the formation of intergranular nitrides, some carbon may be present to prevent the surface of the steel from becoming depleted of carbon. The hardening element in this nitro-carburizing operation is nitrogen, which forms iron nitride as FeN or FeN intragranularly. The purpose of the carbon in the operation is to maintain the concentration of carbon in the surface of the bearing so that the properties are not altered by decarburizing the surface. Standard gaseous and plasma nitriding techniques also may be used for the nitriding operation.

Spall propagation properties of case-hardened M50 and M50NiL bearings

An improved type of rolling element bearing, in which race land regions are protected against wear or scoring, is described. In particular, it is shown that a coating of a hard, wear-resistant material such as titanium nitride, applied to the race land region of a rolling element bearing, is effective in preventing wear or scoring of the race land region.

Rolling element bearing having wear resistant race land regions

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Fairfield, OH, United States of America

Michael Gilbert Johnson