Abstract: The Minimum Quantity Lubrication (MQL) is an environmental friendly lubrication method in metal cutting industries where a very small amount of vegetable oil or biodegradable synthetic ester is sprayed close onto the cutting edge with compressed air. When employed, the usage of the dangerous cutting fluid may possibly be eliminated. This study reports sub-surface analysis of Inconel 718 when finish turning with coated carbide tool TiAlN (PVD) under high speed machining with MQL and dry cutting conditions. The microstructure analysis on the machined surface suggests that plastic deformation has taken place, leading to severe deformed layers of microstructure alteration at the subsurface level. Work hardening under the machined surface was evident from the micro-hardness measurements where higher hardness was measured near the surface and decreases to the bulk material hardness value deep into the subsurface. The results of the experimental study show that machining process and tool wear conditions influence the severity of the deformed layer and micro-hardness value.