Influence of Ultrasonic Surface Rolling on Impact-Shear Wear Behavior of Ni Base 690 Alloy

Ultrasonic surface rolling process (USRP) was applied to improve the surface roughness and microhardness of Inconel 690 alloy. Moreover, the effect of this process on the impact-sliding wear behavior of Inconel 690 alloy was investigated. First, Inconel 690 alloy was selected as the test material, and the size specifications of the specimen were 10 mm×10 mm×5 mm cuboids. The chemical composition of Inconel 690 alloy was Ni 59.48%, Cr 29.5%, Al 0.36%, C 0.022%, Si 0.38%, Mn 0.42%, P 0.012% and S 0.025%. Before ultrasonic surface rolling, different specifications (800, 1000, 1200 and 1500 Cw) of silicon nitride sandpaper were used sequentially to polish the required reinforced surface, and then 0.5 μm diamond grinding paste was used to polish the polished surface until the mirror surface; then absolute ethanol was used to wash in an ultrasonic cleaner for 15 minutes, and finally the sample surface was dried with compressed air. the Inconel 690 alloy’s surface was treated using USRP under specific process parameters. Second, on the basis of an energy control impact-sliding wear test rig, the impact block hit the specimen in motion at a set initial speed (v_i) in the impact direction. Among them, the mass (m) of the normal impact block was 800 g, and the total number of punching cycles (n) per test was 10 000. Immediately afterwards, an optical microscope was used to observe the shape and morphology of the resulting wear marks. The alloy’s surface dynamic mechanical response behavior and damage mechanism were examined under different impact or sliding velocities. The rebound velocity of Inconel 690 alloy under the same test conditions was significantly improved due to the refinement of the surface grain, smoother surface, and reduced tangential friction during punching and shearing wear, and the maximum increase of rebound speed was 30.9%, which occurred when the impact velocity was 30 mm/s. At an impact velocity of 30 mm/s and a tangential velocity of 60 mm/s, the friction coefficients of the untreated specimen and the USRP-treated specimen were approximately 0.23 and 0.17, respectively. Under the same impact-sliding wear conditions, the friction coefficients of USRP-treated specimens was smaller than that of untreated specimens. With the increase of impact velocity, the friction coefficient of the surface decreased, and the friction coefficient treated by USRP was also reduced compared with the friction coefficient of the untreated surface, and the friction coefficient of the reinforced Inconel 690 alloy surface decreased by 26.09%. USRP could effectively decrease the friction force, friction coefficient and impact-sliding dissipated energy during the impact-sliding wear process, thereby reducing the wear degree. In addition, the increased impact or sliding velocity increased the friction force and decreased the dissipated rate of impact kinetic energy.