Abstract
In order to evaluate the surface durability of surface-hardened sintered gears, the fatigue lives of 5 kinds of sintered gears were examined and estimated based on the fracture mechanics. The fatigue tests were conducted using a power circulating gear testing machine. The pore distributions included in the sintered materials were observed and were analyzed statistically. The failure mode of the sintered gears was mainly spalling. The stress intensity factor obtained by FEM analysis for the mode II under a condition of Hertzian contact became larger as the crack length became longer. The estimated fatigue lives were almost the same as the tested fatigue ones. Therefore, it could be said that the crack propagation of the sintered gears depended on the pore size and hardness.
