Effects of Carburized Parts on Residual Stresses of Case-Hardened Spur Internal Gears

Abstract

This paper presents a study on effects of carburized parts on residual stresses of case-hardened spur internal gears. The carbon content of each element of the FEM models due to carburizing was computed on the basis of the relation between carburizing conditions and carbon content distributions. A heat conduction analysis and an elastic-plastic stress analysis during the case-hardening process of spur internal gears were carried out for various case-hardening conditions by the three-dimensional finite-element method (3 D-FEM), considering changes of the thermal expansion coefficient and the yield stress with the temperature and the carbon content, and then residual stresses were obtained. The effects of the case depth, the carburized parts (tooth surface, gear-side and outer surface of rim), the rim thickness and the standard pressure angle on the residual stress were determined.