Impact of powder reuse on corrosion properties in Ti-6Al-4V alloy parts fabricated by laser beam powder bed fusion

Additive manufacturing (AM) is known for its waste-minimizing approach to produce parts. Laser beam powder bed fusion (PBF-LB) is progressively adopted by industry to produce metal products. In PBF-LB, a laser beam selectively melts the areas intended for printing, while the rest of the powder bed remains unused. There is growing interest in recycling and reusing this unused powder feedstock for subsequent AM builds to reduce waste. However, its impact on corrosion behavior remains insufficiently understood. This study examines the effects of powder reuse on the corrosion resistance of as-built AM Ti-6Al-4V parts. Four sets of parts produced using virgin powder (R0), and powder reused five (R5), ten (R10), and fifteen (R15) cycles were selected. These sets were subjected to electrochemical corrosion measurements and material characterizations. The general corrosion resistance of parts decreased by 36% after 15 cycles of powder reuse. In addition, the average current density in the passive region of the R15 samples was measured to be 8.5 times higher than that of the R0 samples, indicating an inferior passive behavior of parts produced with reused powder. The average martensitic grain surface area was slightly reduced from 5.71 µm² (R0) to 5.42 µm² (R15), increasing the grain boundary density. This structural change may make the surface more susceptible to corrosion, reducing part performance in corrosive environments. These findings highlight the importance of considering corrosion performance when using parts produced from reused Ti-6Al-4V powder in PBF-LB.