Performance of cryogenically treated carbide inserts under sustainable cryo-lubrication assisted milling of Inconel X750 alloy

Abstract Owing to their superior features even under elevated temperatures, the nickel-based superalloy Inconel X750 is among the materials demanded in many critical areas. However, such alloys are hard to cut because of their characteristic properties i.e., strain hardening, poor thermal conductivity, high mechanical resistance at elevated temperature, the presence of abrasive carbide fragments and chemical proximity. Therefore, it is important to develop the machinability characteristics of these materials with sustainable machining methods that offer high performance. For this, in this work, a number of attempts were made during the milling of the Inconel X750 alloy. During the experiments, the performance of each cutting tool was investigated by considering three different tools which are uncoated carbide tool, cryogenically treated cutting tool and TiAlN coated tool. Since the machinability of superalloys is difficult in the dry environment, three different sustainable cooling/lubrication conditions such cryogenic LN2, MQL and hybrid cooling/lubrication (MQL + LN2) have been used in conjunction with these tools. In evaluating the effectiveness of the employed methods, flank wear, tool damage types, surface roughness/topography, cutting force and maximum temperatures were analyzed. As a result, even if the cryogenically treated tool performed slightly better than those of untreated, it still did not reach the performance level of the TiAlN coated tools. The hybrid cooling/lubrication system with coated tool offered the best solution in terms of all criteria. On the other hand, MQL outperforms LN2 cooling for tool wear, surface roughness/topography and cutting force, LN2 cooling is better than MQL in temperature reducing.