Comparative Machinability Aspects of Austenitic and Duplex Stainless Steels During Dry Turning

Austenitic stainless steel (ASS) and duplex stainless steel (DSS) are referred as “difficult-to-cut” materials in the manufacturing industry because of different machining difficulties including work hardening, high cutting temperatures and formation of built-up layers. DSS is the preferred replacement for ASS but includes a difficult manufacturing environment. Moreover, the wet machining conditions raise several issues related to the human health, environment, disposition and costing. However, turning of these materials in the dry environment is a challenging task. The present research work is a comparison of machinability aspects of ASS 304 and DSS 2205 in a dry environment using AlTiN coating deposited by two advanced coating deposition techniques including direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). Uncoated tools showed the worst performance at every stage of machining. AlTiN (HiPIMS)-coated tools showed the lowest increase in average surface roughness of 8%, 17% lower cutting force and 1.5-times higher tool life compared to AlTiN (DCMS) tools. DSS 2205 was the most difficult material to machine in dry conditions, exhibiting the lowest average tool life of 3890 mm compared to 4315 mm by ASS 304. Moreover, HiPIMS-coated tools helped in improving the machining performance of DSS 2205 up to some extent.