Surface Stress Regulation and Cutting Performance of the TiN/TiAlN-Coated Tool in Clean LN₂ Cutting Process

The coated tool with an appropriate surface stress can thoroughly resist the dual action of the temperature and stress fields in the liquid nitrogen (LN₂) cutting process, thereby improving its clean cutting performance. The coating compound surface posttreatment experiment and low-temperature LN₂ cutting experiment are conducted to investigate the TiN/TiAlN coating surface residual stress regulation and low-temperature wear behavior, respectively. Compared with polishing and micro-blasting, polishing and cryogenic can effectively regulate the coating surface stress. The residual stress of the treated coating is 61% higher than that of the untreated one. The optimized compound treatment parameters are polishing speed of 500 rpm, polishing time of 30 min, cryogenic temperature of − 190 °C and holding time of 360 min. With the increase in residual compressive stress (absolute value), the wear resistance of the tool is improved. However, the excessive residual compressive stress (absolute value) on the coating surface can lead to the high cutting force and temperature, resulting in severe coating peeling. The high clean cutting performance is obtained when the TiN/TiAlN coating surface has a stress of − 700 to − 650 MPa.