tribology characteristics of ultrasonic impact treated co-based l-605 superalloy

This study investigates the effect of ultrasonic impact treatment (uit) on the surface structure, microhardness, and tribological behavior of l-605 superalloy. the surface of the samples was impacted by a high-frequency (20 khz) spherical tungsten carbide tool for one, two, three, and five passes, using a feed rate of 0.08 mm/min, vibration amplitude of 28 %, and static pressure of 0.1 mpa. results showed that uit significantly deformed the surface microstructure and enhanced surface microhardness, primarily due to work hardening, strain-induced martensitic transformation, and ultrafine grain formation. a single uit pass notably improved wear resistance and reduced the friction coefficient. compared to the annealed alloy, the one-pass uited samples showed wear rate reductions of 74%, 70%, 68%, and 64% under loads of 5, 10, 25, and 75 n, respectively. the average friction coefficient also dropped by up to 80% at 10 n and 74% at 75 n. additional uit passes resulted in marginal microhardness improvement, likely due to strain hardening saturation in the surface layers.