Heat-assisted machining of superalloys: a review

Superalloys are vastly used in the aerospace industry due to their alluring properties such as maintaining their strength at high-temperature applications. Nevertheless, manufacturing these raw materials to the desired geometrical shapes is one of the main challenges of the subtractive manufacturing industry and they are categorized as hard-to-machine materials. Several approaches such as high-speed machining (HSM), cryogenic cooling, minimum quantity lubrication (MQL), and heat-assisted machining (HAM) are introduced to tackle this matter. HAM is a technique that introduces external heat sources to the workpiece (pre-heating or real-time heating methods) to increase the ductility of the superalloy and therefore reduce the yield and shear strength of the workpiece. By this means, the machining parameters demonstrate an improvement compared to conventional machining. This review article focuses on the research approaches conducted to evaluate the effect of the various heat source applications (gas flame, induction, laser, and plasma) on the material properties and the machinability of the superalloys. Additionally, the heating methodology and heat assistance impact on cutting parameters (forces, tool life, surface integrity, and chip morphology) are outlined. Finally, a comparison of the heat source efficiency and the economics of the various heat applications is performed.

Automated summary

Superalloys are extensively used in the aerospace industry for their strength at high temperatures. Different heat source applications are being researched to improve the machinability and material properties of superalloys.