Frictional and wear performance of hard coatings during machining of superduplex stainless steel

In this work, machining of the superduplex stainless steel was investigated using cemented carbide turning inserts with chemical vapor deposited (CVD) TiCN + Al2O3 as well as physical vapor deposited (PVD) TiCN and AlTiN coatings. These three coating system were tested during finish turning operation of superduplex stainless steel. It has been found that unfavorable friction and wear conditions were observed when TiCN- and TiCN + Al2O3-coated tools were used. On the other hand, the AlTiN-coated tool showed a self-adaptive behavior through the formation of tribo-film of aluminum oxide that improves frictional conditions and, consequently, wear resistance during machining of SDSS. This behavior shows that the tool life for inserts coated with PVD AlTiN was approximately two times higher than CVD TiCN + Al2O3. Another important result that can be observed in this work is related with the surface integrity that was improved when machined with cutting inserts coated with PVD AlTiN.