Increase in fatigue limit of gears by compound surface refining using vacuum carburizing, contour induction hardening and double shot peening

Abstract

The surface refining method is a useful technique to improve the fatigue limit of gears. One of the methods is the Carburizing Method. To increase the fatigue limit of the Carburized gears, the following five techniques need to be developed: a) Reduce abnormal surface structure, b) Obtain a fine grain size, c) Decrease the retained Austenitic structure, d) Increase hardness under the surface, e) Improve the residual stress distribution under the surface. For this purpose, the authors conducted a study by using DSG 1 steel gears on the new compound surface refining method consisting of Vacuum Carburizing, Contour Induction Hardening and Double Shot Peening. The results showed that the fatigue limit of the gears processed by the new compound surface refining method achieved 125% better than that of the conventional Vacuum Carburized gears.