Laser surface texture for enhancement of tribological performance of AISI 5115 steel engine valve train components

Abstract

Surface texturing is a promising technique for enhancing the tribological properties of contact surfaces. This study investigates the influence of texture geometry, orientation, and density on tribological efficiency under specific operating load and lubrication conditions. To improve the friction and wear properties of AISI 5115 steel, the surface was textured using a femtosecond fiber laser with three different geometries (triangle, ellipse, and circle) and four densities (5 %, 10 %, 15 %, and 20 %) in their correlation to reduce wettability contact angle to make surface super-oleophilic. The tribological performance of the textured surfaces was evaluated in dry, starved, and lubricated conditions at 100 RPM, 200 RPM, and 400 RPM using a pin-on-disc tribometer. Wear morphology and 3D surface roughness were analyzed using scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM). A comparative analysis based on wear and the coefficient of friction (COF) for various geometries and densities was conducted, providing insights into the optimization of surface texturing for enhanced tribological performance. Compared to the untextured surface, 15 % ellipse texture with an aspect ratio of 0.1 incline at an angle of 45° have reduced COF by 18.8 %, 72.2 %, and 72 % for dry, staved, and lubricated conditions respectively. Similarly, 15 % ellipse texture has reduced wear by 93.2 %, 78.9 %, and 55.5 % in dry, starved, and lubricated conditions, respectively, in comparison to the untextured surface.