The influence of Isotropic Superfinishing on bending fatigue of high strength steel shot-peened gears

The present study is part of a research, regarding fatigue performance improvement by surface treatments. Shot-peening is a well known process for generating a compressive residual stress state: its positive effects on fatigue were widely investigated. In the previous stages of the current research the analysis was focused on the influence of operative parameters, the peen diameter and the Almen intensity, on bending fatigue strength. In the present work the surface treatment of Isotropic Superfinishing (ISF) was considered. The paper provides a wide literary review regarding the main features of ISF treatment and its influence on the reduction of roughness average and wear and on lubrification properties. Moreover, its effects on sliding/rolling contact fatigue and on bending fatigue are reported. Experimental tests were performed on just shot-peened and on shot-peened and superfinished gears made in a carburized quenched high strength steel. Results are presented and discussed according to previous researches and by the application of statistical methods.