Effect of LN 2 and CO 2 Coolants in hard turning of AISI 4340 steel using tungsten carbide tool

Abstract Recently, Cryogenic cooling has witnessed a significant role in improving efficiency, increasing the quality of machined parts, and developing a techno-economic and eco-friendly acceptable methodology in the machining of components. This study deals with the effect of hardened AISI 4340 steel at 48 HRC against uncoated WC cutting tool analysed through the use of dry, cryogenic liquid nitrogen (Cryo-LN 2 ) and cryogenic liquid carbon dioxide (Cryo-LCO 2 ) cooling environments. The input parameters for this hard turning condition include cutting velocity, feed rate, and depth of cut. A study of the machining performance of cutting temperature, surface roughness, material side flow, flank wear, microhardness, and chips morphology have also been made. The experiment results revealed the effective lowering of the cutting temperature, better surface roughness and reduced flank wear for LCO 2 and LN 2 coolant by cryogenic cooling against dry cutting condition. Compared to dry and cryogenic LCO 2 cutting environments, the machined zone of a cryogenic LN 2 exhibited the highest microhardness value. The main reason for this was the decrease in the thermal softening effect. Overall, the performance of the cryogenic LN 2 environment condition was effective and efficient in the turning process compared to dry and cryogenic LCO 2 .