Effect of Machining Parameter on Hardness During Turning Inconel 718 Under Minimum Quantity Lubrication (MQL)

Abstract

Inconel 718 has become a leading material among superalloy materials and this material is referred to a family of austenitic nickel-chromium-based superalloys. These materials are known as the higher sheer strength, low thermal conductivity, high chemical affinity, not easy to cut (difficult-to-cut materials) and also has the tendency to works harden materials because of the hardness and high temperature resistant. In this experiment, an attempt has been made to model the machinability evaluation through the response surface methodology in machining of Inconel 718 material using CNC turning. The machining processes started with cutting speed (Vc = 90, 120 and 150 m/min), two levels of cutting depth of cut (d = 0.30 and 0.50 mm), two levels of feed rate (f = 0.10 and 0.15 mm/rev) and dry, MQL volume flow rate (MQL 50 ml/h and MQL 100 ml/h). The change increased the hardness of the work material machined surface high sheer strength, low thermal conductivity and also has the tendency to work hardened. This information is useful for the mould maker to select the best cutting condition.The detailed microstructure analysis shows that worn out tools caused over heated of the machined surface and changes the microstructure of the work material.