Load Bearing Capacity of Super-Carburized Gears

This paper describes a study on the load bearing capacity of super-carburized gears. Test gears and rollers of MAC14 and SCM415 steels were super or eutectoid-carburized under different carburizing conditions. The impact and bending fatigue tests for test gears and the contact fatigue test for test rollers were carried out. The effects of case depths on the impact and bending fatigue strengths of gears and the surface durability of rollers were determined. The impact breaking limit energy of super-carburized gears was found to be larger by about 15% than that of eutectoid-carburized gears irrespective of case depth. The bending fatigue strength of the super-carburized gear was found to be almost equal to that of the eutectoid-carburized gear. The surface durability of the super-carburized roller becomes larger with an increase of case depth and is larger than that of eutectoid-carburized rollers in the case of larger case depth. The surface failure modes for super and eutectoid-carburized rollers were spalling. The load bearing capacity of super and eutectoid-carburized gears was found to become larger by shot-peening.