Effects of Heating Time, Electric Power and Frequency on Bending Fatigue Strength of Induction Hardened Gears

Abstract

The measurement of hardened layer and the bending fatigue test of S35C and S45C steel gears induction-hardened under various heating conditions were carried out, and then profiles of hardened layer and S-N curves (bending fatigue strength) were obtained. Effects of the heating time, the electric power and the frequency on profiles and micro-structures of hardened layers of gears were examined. Relationship between the bending fatigue strength and the profile of hardened layer was determined. Optimum heating conditions for the bending fatigue strength of induction-hardened S35C and S45C steel gears were indicated.

Hardened Layer and Bending Fatigue Strength of Induction Hardened Thermally Refined Steel Gears

“…The bending fatigue test machine (5) used consists of a fuel injection pump for diesel engine and its driving apparatus ①, pressure controller ② and loading apparatus ③ as shown in Fig.2. The test gear is supported with a shaft and three teeth of an internal gear fixed to the bed of the test machine.…”

“…It has been known that the austenite transformation of thermally refined steel for rapid heating is more superior to the case of as-rolled steel, but the results for induction hardened gears have not been published. In the previous papers, effects of hardening conditions on the hardened layer and the bending fatigue strength of induction hardened gears made of as-rolled S35C and S45C steels (3)- (5) had been published.…”