Investigation of the effect of ball-burnishing treatment applied to Al 7075-T6 alloy on mechanical and crystallographic properties

Abstract

ABSTRACT In this study, the mechanical, microstructural, and crystallographic effects of ball-burnishing applied to Al 7075-T6 alloy at 0.15–0.30 mm penetration depth, 0.15–0.30–0.60 mm/rev changing feed rates and 100–200 rpm range were investigated. After the ball-burnishing processes were carried out in different parameters, surface roughness measurements were applied to determine the surface qualities, and hardness and impact energy tests were applied to characterise the mechanical properties. Dislocation density and texture coefficient values were calculated by determining the crystallographic properties using X-ray diffraction. It has been determined that the ball-burnishing process directly affects the surface roughness, depending on the increasing rotational speed and feed rate. As a result of microstructural investigations, the average grain size decreased with increasing amount of deformation on the sample surface. At 200 rpm ball-burnishing parameter, the surface hardness of the sample increased by approximately 41% compared to the initial state and was measured as 265 HV2. It was determined that the ball-burnishing process did not positively affect the impact of the toughness of the alloy. The reason for this is that the roughness and scratches on the surface caused by the ball-burnishing process have a notch effect, increasing the crack formation and propagation speed.