Recent Advances in Machining of Inconel 750: Challenges, Tool Wear Mechanisms, and Strategies for Machinability Improvement

Nickel-based superalloys such as Inconel 750 have become indispensable engineering materials in aerospace, power generation, and high-temperature structural applications due to their exceptional strength, corrosion resistance, and thermal stability. These properties arise primarily from their complex microstructure, solid-solution strengthening, and precipitation-hardening mechanisms, which enable them to maintain mechanical integrity under extreme service conditions. However, the same characteristics that make Inconel 750 desirable for critical applications also render it extremely difficult to machine. The alloy exhibits high work hardening rates, low thermal conductivity, and strong chemical affinity with cutting tool materials, which collectively lead to elevated cutting temperatures, rapid tool degradation, and poor surface integrity during machining. Consequently, improving the machinability of Inconel 750 has become a significant research focus within the field of advanced manufacturing. This review presents a comprehensive analysis of recent developments in the machining of Inconel 750, emphasizing the fundamental challenges, dominant tool wear mechanisms, and modern strategies developed to enhance machinability. The discussion begins by examining the intrinsic material properties of Inconel 750 that contribute to machining difficulty, including strain hardening behavior, high temperature strength, and microstructural stability. These properties often lead to severe plastic deformation in the primary shear zone, excessive heat generation at the tool–chip interface, and unstable chip formation processes. As a result, machining operations such as turning, milling, and drilling of Inconel 750 frequently encounter issues such as high cutting forces, accelerated tool wear, poor dimensional accuracy, and compromised surface integrity. A significant portion of this review focuses on the mechanisms of tool wear observed during machining of Inconel 750. Various wea