Effect of bias voltage on mechanical properties, milling performance and thermal crack propagation of cathodic arc ion-plated TiAlN coatings

Abstract

The influence of bias voltage on the cutting performance, thermal crack initiation and propagation of TiAlN coatings was investigated in face milling of 3Cr2Mo steel at wet conditions. The purpose was to increase the understanding of the relationship of mechanical properties, residual stress and failure mechanisms. The Ti0.33Al0.67N coatings by muti-arc ion plating technology were deposited on WC-Co cemented carbide substrate at various bias voltages, which were varied between -40 V, -80 V and -120 V. It was found that the tool life was mainly limited by chipping of the cutting edge, caused by thermal crack interaction. The cutting performance and behavior of thermal crack of coated inserts deposited at different substrate-bias voltages were compared. Some additional mechanical, texture and residual stress were also presented and discussed. The result showed that the superior toughness and structure with (200) preferred orientation played a key role in suppressing the formation and propagation of thermal crack, while a relatively high level of residual stress would retard the initiation and propagation of thermal crack when they exhibit a similar behavior of toughness and (200) preferred orientation.