A Study on Strength and Failure of Induction-Hardened Chromium-Molybdenum Steel Spur Gears

Abstract

In order to detcrmine the strength of induction-hardened chromium-molybdenum steel spur gears, fatigue tests were performed using a power circulating gear testing machine. As the result, the surface durability was obtained in connection with dynamic loads and it was shown by microscopic observation that there occurred fatigue tooth breakages starting from the middle tooth height which are induced by the spallings on tooth surface or sometimes bending fatigue fractures at the tooth roots depending on the dimension of tooth width. Moreover, it was made clear that tooth surface strength of induction-hardened gears must be evaluated in terms of stresses beneath the surface.