Due to rapid work hardening, Inconel is a metal that is difficult to form and machine using traditional cold forming techniques. After xxx machining passes, work hardening often causes plastic deformation of the workpiece or tool in subsequent machining. For this reason, age-hardened Inconel alloys, such as 718, are often cut strongly but slowly using hard tools, thereby minimizing the number of strokes required. Alternatively, most of the machining can be carried out with the workpiece in solid solution form, with only the final step carried out after age hardening. However, some claim that Inconel alloy can be machined at very fast speeds at very fast spindle speeds using a multi-groove ceramic tool with a small cutting depth and a high feed rate, as this causes local heating and softening in front of the groove.
External threads are machined to a single point thread using a lathe, or rolled using a screw under solution treatment conditions (for hardenable alloys). Inconel alloy 718 can also be rolled by induction heating to 700 °C (1,290 °F) after full aging without increasing grain size. Holes with internal threads are made by thread milling. Settling discharge machining (EDM) can also be used to form internal threads.
