Additive manufacturing defects and its impact on metal corrosion: A review

Abstract This review investigates defect formation mechanisms in metal additive manufacturing (AM) and their impacts on corrosion resistance. Utilizing discrete/stacking principles, AM enables integrated fabrication of complex components, with rapid solidification creating gradient fine-grained microstructures that enhance mechanical properties. However, thermodynamically induced defects—including lack-of-fusion pores, cracks, and surface roughness—significantly degrade corrosion performance through three mechanisms: Cr/Mo segregation reduces pitting potential by 180 mV at pore sites; crack-induced stress concentration decreases passivation film fracture energy by 40%; and roughness-triggered oxygen concentration cells elevate corrosion current density by 2-3 orders of magnitude. A coordinated strategy combining process optimization, defect suppression (rotational scanning reduces porosity by 50%), and post-treatment enhancement (HIP with electrolytic polishing achieves Ra<0.5 μm) is proposed. Future research should prioritize multiphysics corrosion-defect prediction models and novel corrosion-resistant alloy designs to enable reliable engineering applications of AM components