Influence of shot peening on the rolling contact fatigue resistance of Cu-Ni austempered ductile iron

Abstract

Shot peening is known to prolong the bending fatigue life of components. However, very few works have been conducted on the tribological behaviour of ADI after shot peening. This paper studies the influence of shot peening on the contact fatigue resistance of Cu-Ni ADI. Lubricated rolling contact fatigue tests were conducted on as-austempered ADI and shot peened ADI specimens. The results show that the shot peened specimens exhibit lower rolling contact fatigue resistance than their counterpart as-austempered specimens. This was attributed to the high surface roughness induced by the shot peening process, which caused a boundary lubrication regime. In fact, the negative impact resulting from the roughened surface is greater than the benefits prompted by the induced compressive residual stresses, higher surface hardness and austenite to martensite transformation.