The influence of vibration amplitude on AA7075-T6 corrosion resistance improvement during ultrasonic-assisted burnishing

Abstract

Corrosion resistance of materials is predominately dependent on their surface roughness. Therefore, surface finishing techniques can effectively improve the corrosion resistance of the components. Ultrasonic-assisted burnishing (UAB) process is a newly developed surface finishing technique capable of flattening the surface of components without material removal. This research experimentally investigated the effects of amplitude in the UAB process on surface roughness and corrosion performance of AA7075-T6 aluminum alloys. Turned sample (control) was treated by conventional burnishing (CB), followed by UAB with an amplitude of 10, 20, and 30 µm. Then, the surface roughness, microstructure, microhardness, and corrosion resistance of the treated samples were assessed. The surface roughness showed an improvement upon burnishing of the samples, where the best surface was achieved by UAB with an amplitude of 10 µm. UAB process also led to grain refinement such that finer grains could be achieved by increasing the amplitude. Microhardness also increased after the UAB process which got intensified by increasing the amplitude. The turned sample showed the least corrosion resistance, while the UAB-treated specimens (amplitude of 10 µm) exhibited minimal corrosion rate. Furthermore, the enhancement of UAB amplitude increased the surface roughness, causing a decline in corrosion resistance.