Abstract
For Austempered Ductile Iron (ADI) gears, a shot-peening may be utilized to improve the bending fatigue strength. However, under some shot-peening conditions, the increase of surface roughness by shot-peening may decrease the surface durability of ADI gears. The authors investigated the influence of shot-peening on the surface durability of ADI rollers using a disk machine which simulates the rolling and sliding action of gears. Two types of shot-peenings were adopted, that is, the conventional shot-peening and the fine particle shot-peening. The results are summarized as follows : (1) The increase of surface roughness by the conventional shot-peening causes the decrease of surface durability. This is confirmed by testing rollers polished after the conventional shot-peening. (2) The surface roughness after the fine particle shot-peening is smaller than that after the conventional one. The surface durability of ADI rollers after the fine particle shot-peening is superior to that after the conventional one. (3) Consequently, if shot-peening is applied to improve the bending fatigue strength of ADI gears, the fine particle shot-peening is useful to prevent the decrease of the surface durability.
