Comparative investigation on surface integrity for conventional and ultrasonic vibration–assisted cutting of in situ TiB₂/7050Al MMCs

The particle reinforced metal matrix composites have drawn attractive attentions in modern industries due to their excellent properties such as low density, improved strength, and wear resistance. However, due to the existence of hard ceramic particles, it shows poor machinability such as large cutting force and unstable machined surface quality using traditional cutting method. In this study, taking advantage of ultrasonic vibration–assisted cutting method such as reducing cutting force and improving machining quality, the machined surface integrity of a new kind of in situ TiB₂/7050Al metal matrix composites was comparatively investigated between conventional milling (CM) and ultrasonic vibration–assisted milling (UVM). It was much important to match appropriate ultrasonic vibration parameters and cutting parameters for achieving a smaller surface roughness and larger surface compressive residual stress in UVM. The depth of compressive residual stress layer in the subsurface was about 90 to 120 μm, which was deeper than that of CM. Besides, ultrasonic vibration did not make obvious impact on the surface hardness and microhardness. In this paper, for ultrasonic vibration–assisted milling in situ TiB₂/7050Al MMCs, the vibration parameters and cutting parameters were recommended as frequency of 30 kHz, amplitude of 4 μm, cutting speed of 30 m/min, feed rate of 0.05 mm/z, and cutting depth of 0.5 mm; the surface roughness was 0.34 μm and compressive surface residual stress was − 208 MPa. Therefore, a proper match of ultrasonic parameters and cutting parameters could significantly enhance the surface integrity in ultrasonic vibration–assisted milling in situ TiB₂/7050Al MMCs.