Flank Wear Mechanisms of Zirconia Toughened Alumina Cutting Tools during Machining of Steel

Two zirconia toughened alumina (ZTA) cutting tool grades SN60 (<10% ZrO₂) and AZ5000 (between 10-20% ZrO₂, fine grained) were used for the evaluation of wear mechanisms when machining a high tensile steel (AISI 4340). Experimental studies were carried out at various cutting speeds (300-600 m/min), feed rates (0.10.4 rnrn/rev) and depths of cut (0.5-2.0 mm), in the dry condition. The worn cutting edge surfaces were examined by optical and scanning electron microscopies (SEM). The flank wear was determined by a toolmaker microscope. The AZ5000 grade was found to provide better flank wear resistance under the conditions investigated. The wear behaviour and wear mechanisms of the tools are discussed in relation to the cutting parameters (i.e. cutting speed, feed rate and depth of cut) and microstructures.