An investigation into the ball burnishing of aluminium alloy 6061-T6

Abstract

Burnishing has been widely used to produce excellent surface finish, work hardening, and compressive residual stress by plastically deforming the workpiece surface. There have been very few studies concerning the effect of burnishing parameters on the fatigue life. The purpose of this work is to study the relationships between the fatigue life, the residual stress, and the ball burnishing process parameters. Experimental work was carried out on a lathe to establish the effect of three burnishing parameters, namely the burnishing speed, burnishing force, and burnishing feed, on the residual stress and fatigue life of aluminium alloy 6061-T6. The residual stress distribution in the surface region due to ball burnishing is determined using a deflectionetching technique. The number of cycles to failure is determined for each specimen using a universal-type fatigue machine, which is suitable for testing specimens requiring oscillatory or reciprocating motion. It was found that all input parameters have controlling effects, to different extents, on the residual stress and fatigue life. The results showed that the residual stress plays an important role in controlling the behaviour of fatigue. The burnishing force and burnishing feed are the most important parameters controlling the values of the compressive residual stress which, in turn, delay crack initiation, resulting in an increase in the fatigue life.