Investigation of Thermally Assisted End Milling of 254 SMO Super Austenitic Stainless Steel

Given the challenges associated with machining super austenitic stainless steels (SASS), including their high mechanical strength, low thermal conductivity, high work-hardening tendency, and high ductility, thermally assisted machining (TAM) has emerged as a promising approach to enhance the machinability of these materials. Thus, in this study, the machining forces, tool wear, and surface finish generated under different cutting conditions in the milling of SASS 254 SMO heated to 200 ºC were compared to the results obtained in a related study applying dry cutting and commercial nanofluid in minimum quantity lubrication (NMQL). The results showed that machining forces in TAM were, on average, 18.4% lower than in dry cutting and similar to those in NMQL milling (reduction of 19.3%), indicating that thermal softening facilitated chip deformation and reduced machining forces. The tool wear rate in TAM was lower than that in dry cutting, although it was slightly higher than that in NMQL milling (mainly at the end of the test). However, the presence of adhered material on the machined surface and the formation of defects, such as smearing and side flow, imply that the elevated temperature of the workpiece may adversely affect its surface quality.