This study focuses on investigating the cutting tool performance of a chemical vapor deposition (CVD) coated carbide tool in machining hardened AISI 4340 alloy steel under environmentally friendly sustainable minimum quantity lubrication (MQL) environment. The input parameters for turning experiments were configured in a high-speed regime, with the cutting speed (V) varying from 300 to 400 m/min, the feed rate (F) between 0.1 and 0.2 mm/rev, and depth of cut (DOC) in the range of 0.2 to 0.4 mm using a multilayer coated carbide tools TiCN/Al₂O₃. The experiments were randomly conducted using the Taguchi method L9 orthogonal array, which accommodated three factors, each with three levels. The longest tool life of 7.10 min was noticed under low machining parameters at a cutting speed, V=300 m/min, F=0.1 mm/rev, and DOC=0.2 mm. Analysis using S/N ratio revealed that the machining speed has a most profound influence on tool life in comparison to feed rate and depth of cut. Wear mechanisms such as cutting-edge chipping was commonly observed, whereas at high depth of cut catastrophic failure was noticed due to the flaking of the cutting tool material. © 2024, Malaysian Tribology Society (Mytribos). All rights reserved.