Surface preparation and wear mechanism of high-strength microtextured aluminum alloys using combined cutting and ultrasonic rolling process

Abstract

Cutting processes can form microtextures with alternating peaks and valleys on the surface, while ultrasonic rolling can cause material flow from peaks to valleys and bring about plastic deformation strengthening, which avoids the reduction in surface strength associated with microstructures processed by material removal. This study utilizes a combined approach of cutting and ultrasonic rolling process (CURP) to create high-strength, wear-resistant microtextured surfaces on aluminum alloys. The research investigates the principles of point contact wear on microtextured surfaces. Models were developed for the contact area between cutting roughness peaks and the rolling element to analyze the shape of the contact area and the forces acting on the rolling element under different processing parameters. Experiments were conducted with single and multiple passes of ultrasonic rolling under different cutting parameters to establish the relationship between indentation size and processing parameters. Friction and wear experiments were performed to explore the wear mechanisms on surfaces with microtexturing. The results revealed that the length of the indentation is positively correlated with the cutting feed rate. At the same indentation depth, a larger feed rate results in a longer indentation length. As the angle φ between the rolling direction and the cutting mark decreases, single indentations shift from symmetrically distributed along the midline of the rolling to one side. When the feed rate is high and the overlap rate is low, the roller-burnished surface exhibits a uniformly distributed sector-shaped pit area. However, with an overlap rate of 25 %, sector-shaped pits disappear under smaller feed rates. Microtextured surfaces are less prone to microcracks and material peeling abrasion under light loading conditions. With an increase in contact stress during heavy loading, surfaces with higher degrees of work hardening, such as the CURP specimens, become more susceptible to material peeling.