Experimental Investigation of Microstructure and Machinability Enhancement of AISI 310 Austenitic Stainless Steel through Heat Treatment and Annealing

AISI 310 austenitic stainless steel is widely employed in high-temperature and corrosive environments due to its excellent oxidation resistance and mechanical stability. However, its poor machinability resulting from high work-hardening rate and toughness poses significant challenges during conventional machining. This study presents an experimental investigation on the influence of heat treatment and annealing on the microstructure, surface roughness, and machinability of AISI 310 stainless steel during turning operations. Three material conditions—untreated, stress-relieved at 600 °C, and fully annealed at 1050 °C—were examined. Turning experiments were conducted under controlled cutting speed and depth of cut while varying feed rates. Cutting forces were measured using a three-component dynamometer, surface roughness was evaluated using a stylus profilometer, and microstructural evolution was analyzed through metallographic examination. The results demonstrate that annealing significantly refines grain structure, reduces cutting forces, and improves surface finish. The study establishes a strong correlation between microstructural modification and machinability enhancement, confirming annealing as an effective pre-machining treatment for AISI 310 stainless steel.