Fabrication, characterization, and MQL assisted machining of layered functionally graded 316L/Distaloy AB composites by powder metallurgy method

This study investigates the fabrication and characterization of layered functionally graded 316L/Distaloy AB composites produced via powder metallurgy, as well as their machinability under minimum quantity lubrication (MQL)-assisted milling. Machining performance was evaluated in terms of cutting temperature, surface roughness (Ra), vibration amplitude, energy consumption, and tool wear analyses. The results of this study show that bilayered composites (316L/Distaloy AB) exhibited the highest ultimate tensile strength due to effective interface-driven load transfer and precipitation strengthening. Increasing the number of layers (316L/Distaloy AB/316L and Distaloy AB/316L/Distaloy AB) resulted in greater microstructural heterogeneity and a slight increase in residual porosity, which adversely affected tensile strength. Furthermore, the average cutting temperature, surface roughness, cutting power and vibration amplitude were found to be 16%, 25%, 25% and 20% lower, respectively, when layered functionally graded composites were machined using MQL-assisted milling compared to dry machining. In addition, the application of MQL cooling-lubrication has been shown to significantly reduce tool wear progression by mitigating adhesive, abrasive, and diffusion wear mechanisms. This integrated microstructure–machinability framework provides a more profound insight into the coupled mechanical and tribo-thermal behaviour of layered PM alloys and contributes to the advancement of sustainable machining strategies for graded metallic systems.