MACHINE ELEMENT, CONSTANT VELOCITY UNIVERSAL JOINT AND PROCESS FOR MANUFACTURING THEM

摘要

A machine element that eliminates the need of descaling processing after induction hardening to thereby enable coping with in-line processing requirement and to attain cost reduction, and that realizes reduction of deformation after induction hardening and prolongation of endurance life in a high-temperature atmosphere; and a process for manufacturing the machine element. There is provided a machine element having a rolling groove for rolling of a rolling element, wherein at least the surface layer of the rolling groove is induction hardened to thereby form a hardened layer. The hardened layer of the rolling groove is provided with a carburized layer by increasing of the carbon concentration over that of the base material. The carburized layer is formed by carrying out induction hardening in oil.