Influence of laser surface texture orientation on the tribological behavior of the WC-Co/Ti6Al4V pair in dry and lubricated conditions

Abstract

The titanium alloy Ti6Al4V has low machinability due to its low thermal conductivity, strong work hardening, adhesion tendency, and high chemical reactivity. To machine it, cutting-tools with high hardness, thermal conductivity, and Young's modulus, like tungsten carbides (WC-Co), are required. During machining, chip sliding over the tool's rake face causes severe friction and heat, exacerbated by the shearing process. Techniques to improve machining performance include reducing contact length with chip-breaker geometries, using coolants/lubricants, specific coatings, and texturing active cutting surfaces. Texturing reduces contact area and enhances retention of cutting fluids and abrasive particles, potentially lowering temperatures and forces, and extending tool life. However, gaps remain in understanding the effects of texture orientation. This study characterizes the tribological behavior of the WC-Co/Ti6Al4V pair in flat-on-flat reciprocating tests under a 50 N load and a sliding distance of 50 m. Linear textures with a depth of 13 μm, spaced 0.1 mm apart, were tested at orientations of 0, 45, and 90° relative to the sliding direction, under both dry and lubricated conditions. The results showed that the textures were most effective in lubricated conditions, particularly with a perpendicular orientation, while severe adhesion in dry conditions worsened the tribological performance.