Dry machinability analyses between free cutting, resulfurized, and carbon steels

Free cutting steels, also referred to as free machining steels, include free cutting additives to improve tool life and machinability. Despite their wide applications in industry, scarce information is available to ensure reliable, safe, and productive cutting operations. This work presents a comparative study of the machinability of different free cutting steels to realize their real behavior and potential as alternatives to conventional steels. Three free cutting steels (SAE 12L14, 11L17, and 11L41), a resulfurized steel (SAE 1144), and a low-carbon steel (SAE 1010) were experimentally investigated employing turning tests. Key process parameters such as wear evolution, surface roughness, and material adhesion were analyzed. The results showed that low cutting speeds tend to improve tool life in free cutting steels, while this advantage disappears at high cutting speeds. Energy-dispersive X-ray spectroscopy analyses showed that chemical elements, such as Mn, S, and, especially Pb, play a significant role in self-lubrication at the cutting tool tip, thus reducing tool wear at low and medium cutting speeds. Besides, thermal simulations were done to verify the correspondence between material properties, machinability, and thermal field in the tool/chip interface.