Turning of AISI 304 austenitic stainless steel with cryogenic treatment applied cutting tools

In this study, turning operations of AISI 304 austenitic stainless steel were experimentally investigated using dry and MQL application with cutting tools with and without cryogenic treatment at different cutting parameters. For this purpose, the cutting tools were tempered twice (2 hours at 200 °C) with a deep cryogenic treatment at -146 °C for 24 hours. Turning experiments were conducted with four different cutting speed (160, 190, 220, 250 m/min) four different feed (0.1, 0.15, 0.2, 0.25 mm/rev) and fixed depth of cut (2 mm) parameters. The cutting tool wear tests were carried out with 250 m/min cutting speed, 0.1 mm/rev feed and 2 mm fixed depth of cut parameters. In the experiments, cutting forces, surface roughness, cutting tool wear, cutting tool vibration, chip morphology and microhardness were investigated in order to determine the effects of cryogenic treatment, MQL application and cutting parameters in turning of AISI 304 austenitic stainless steel material. Cryogenic treatment was found to increase the microhardness of the cutting tool by 20%. It was observed that tool wear with cryogenically treated tools under MQL conditions was less than the tool wear of untreated tools and without MQL conditions. In the turning experiments, it was determined that as the feed rate increased, the main cutting force, surface roughness and vibration increased, and with the increase in cutting speed, the main cutting forces, surface roughness and vibration decreased. When the chips formed in the machining experiments were examined, while continuous chip was obtained at low cutting parameters of all cutting conditions, discontinuous chips were obtained at high cutting parameters. In general, in experiments where MQL application and cryogenic process were used together in all machining conditions, the machining performances were better than the other conditions.