Abstract
The effect of shot-peening on tooth surface strength of carburized gears has not been clarified because of its complicated mechanism. Micro pitting was caused by the load that was lower than spalling appeared in hardened gears. And micro pitting becomes the trigger of serious accident to be tooth breakage etc. In this study, the authors investigated the generation mechanism of micro pitting and the effect of shot-peening was investigated by using the stress analysis. As a result of theoretical analysis, extremely high maximum shearing stress was caused in the contact surface. Therefore, micro pitting was caused from the surface originated crack caused by extremely high shearing stress at real contact area. D value that is the index of contact condition strongly influence the occurrence of micro pitting and that influence is the same as the thermally refined steel gears. Also, the influence of the shot peening takes part in the form of the compressive residual stress when the stress is analyzed and surface roughness of the contact surface when D value was calculated.
