Surface Integrity Evaluation When Turning Inconel 718 Alloy Using Sustainable Lubricating-Cooling Approaches

This novel work focuses on turning Inconel 718 alloy using different sustainable lubricating-cooling techniques. Cryogenic machining (Cryo), minimum quantity lubrication (MQL) and nanofluid MQL (NFMQL) were applied and their performances in terms of obtainable surface integrity evaluated in comparison with dry cutting (dry) and wet machining (wet). The surface integrity was analyzed from the aspect of surface roughness, surface morphology and defects, microhardness, microstructure, and chip morphology. The experimental results revealed that Cryo offered overall better performances when compared to dry, wet, MQL and NFMQL strategies: lower surface roughness, fewer surface defects and lower chip compression ratio were observed. Furthermore, increasing the cutting speed led to higher surface roughness and incidence of surface defects for all the applied strategies, except for Cryo.