Evaluating the machining characteristics of 2507 super duplex stainless steels produced by laser powder bed fusion technology

Abstract

Owing to its exceptional strength and ability to resist corrosion, 2507 Super Duplex Stainless Steel (SDSS) is widely used in demanding engineering applications. Moreover, the advancement of additive manufacturing (AM) technologies, including Laser Powder Bed Fusion (LPBF), has enabled the production of near-net-shape components that are exceptionally well-suited for demanding environments. However, owing to rapid solidification and unique microstructures, these materials exhibit higher hardness and strength, posing significant challenges during machining. Additionally, dealing with high surface roughness remains a persistent issue. Therefore, the study investigated the effect of milling parameters on the machinability of LPBF-fabricated 2507 SDSS under dry cutting conditions. Experiments were conducted at cutting velocities of 15, 30, and 45 m/min, feed rates of 0.02, 0.06, and 0.1 mm/rev, and a constant depth of cut of 0.5 mm. The ferrite-dominated microstructure made the material harder and less ductile, resulting in difficult machining behavior. Results showed that cutting feed and feed had a significant influence on temperature, and surface roughness, than the cutting velocity. While, changes in cutting velocity significantly influenced the cutting force. Increasing cutting velocity reduced resultant cutting force by 22.4-46.1%, whereas increasing feed increased force by 48.8-113.2%. Machining temperature increased by 17.2-112.6% with higher cutting velocities and by 28.8-94.5% with higher feed. An optimal surface roughness of 0.32 mu m was achieved at high cutting velocity and low feed, representing a 96% improvement over the as-built surface condition. Chip morphology was strongly feed-dependent, with higher feed promoting chip fragmentation.