Machinability investigation of 254 SMO super austenitic stainless steel in end milling under different cutting and lubri-cooling conditions

The application of super austenitic stainless steels (SASS) in the petroleum, chemical, and naval industries has gradually increased owing to their intrinsic properties, such as corrosion resistance and durability. Consequently, the low machinability of SASS is due to its high mechanical strength, low thermal conductivity, and high tendency to work hardening. The understanding of how cutting conditions impact the machining of this material remains limited, highlighting a deficiency in information regarding strategies to enhance its machinability. In this context, the present work analyzes the influence of different cutting and lubri-cooling conditions on machining forces, tool wear, surface roughness, and chip features produced during end milling of SASS 254 SMO. The results showed that depth of cut was the most influential parameter on static and dynamic machining forces, whereas the effect of cutting speed was low expressive. The nanofluid minimum quantity lubrication provided more stability in force values and lower tool failures on the peripheral cutting edge for the total machined length than in flood conditions. In comparison, dry machining resulted in higher tool failure and machining forces. Low roughness values were generated on the sample surface because the end-cutting edge did not exhibit substantial failures. The lubricating effect of NMQL also improves the surface quality of the machined workpiece. On the other hand, dry machining resulted in adhered materials owing to high temperatures in the cutting zone and flood milling in removing material particles from the surface due to work hardening. Furthermore, the generated chips corroborated the analysis of the lubri-cooling effects on the machinability of the material, highlighting the higher temperatures produced during dry cutting owing to changes in the surface color of chips.