Wear behavior and cutting performance of CrAlSiN and TiAlSiN hard coatings on cemented carbide cutting tools for Ti alloys

Recently, multicomponent CrAlSiN and TiAlSiN coatings have been developed in order to gain high hardness and good thermal stability. In this study, the influence of TiAlN, CrAlSiN and TiAlSiN coatings on the wear behavior and cutting performance of the carbide cutting tools was investigated in dry machining of a Ti-6Al-4V alloy. TiAlN, CrAlSiN and TiAlSiN coatings were deposited on tungsten carbide milling inserts by using cathodic arc evaporation. The deposited TiAlN, CrAlSiN and TiAlSiN possess high hardness of 31 +/- 1 GPa, 36 +/- 2 and 35 +/- 2 GPa, respectively. After annealing at 700 degrees C in air, the hardness of the CrAlSiN and TiAlSiN still keeps as high as 35-36 GPa, while the hardness of TiAlN decreases to 26 GPa. The main wear modes for the TiAlSiN-, TiAlN coated- and uncoated tools are abrasion and adhesion. The nanocrystalline TiAlSiN coatings retard the tool wear as compared to the TiAlN-coated tools. At a high cutting speed of 350 m/min, the tool life of the CrAlSiN coatings exceeds the TiAlSiN-, and TiAlN-coated and uncoated tools by 2.9, 42 and 9.5 times, respectively. The CrAlSiN coatings show high wear resistances in dry machining of Ti-6Al-4V alloys, and thus possess the best cutting performance. (C) 2014 Elsevier B.V. All rights reserved.