الفهرس 
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Abstract
Superalloys are high-temperature resistant alloys that are mainly used in jet engines, gas turbines, chemical process industries, and other applications demanding heat and/or corrosion resistance. Because they exhibit high mechanical strength, ductility, creep strength at high working temperatures, high fatigue strength, and also excellent resistance to oxidation and corrosion even at elevated operating temperatures. However, these superior properties make the drilling of such alloys a complicated task, so Ultrasonic-Assisted Drilling (UAD) is used in this study to improve the machinability of such alloys.UAD is one of the promising drilling techniques in the aerospace industry dealing with difficult-to-cut materials. The principle of this technique is using the motion of a twist drill (rotational and axial motion) superimposed on it an ultrasonic oscillation at high frequency (16–40 kHz) and low oscillation amplitude (2–10 μm) in the axial feed direction to the tool or workpiece based on the ultrasonic generation system design. In this study, a comparison between UAD and conventional drilling (CD) is presented using single and double-margin AlTiN-coated carbide twist drills at different working conditions. The experiments were performed on plates of Inconel 601 (nickel-based superalloy), which is classified as a difficult-to-cut alloy due to its high nickel content (60%), high hardness (43 HRC), and low thermal conductivity. The experiments were performed using DMG Mori Ultrasonic 20 linear machining center (E-JUST), which is equipped with an ultrasonic tool holder oscillating at 20 kHz and 7 μm amplitude.Full factorial design of experiments approach was employed, and the results were statistically analyzed to find the most significant factor affecting the process responses using ANOVA. Many output responses were measured; thrust force, torque, diametral oversize, circularity error at hole entry and exit, cylindricity error, hole taper angle and surface roughness (Ra). Furthermore, tool wear and chip morphology were studied. Finally, a comparison between the performance of the single and double-margin twist drill was presented.The main results showed a remarkable improvement in several responses when using UAD compared to CD using single and double-margin drills. However, by comparing the performance of single and double-margin drills, it was found that the single margin drills gave accurate and high-quality holes compared with the double-margin ones. On the contrary, the thrust force and torque required for the drilling operation were less when using the double-margin drills.