Research on the Effect of Microstructure Modulation on the Corrosion Resistance Behaviour of L-PBF Alloy 718

The micro-structures and corrosion behavior of laser powder bed fusion (L-PBF) alloy 718 (power 140 W, speed 800 mm s −1 ) after various heat treatments (650 °C, 940 °C, and 1020 °C) were investigated by electrochemical analysis. The result shows that as-received samples, the most prone to pitting corrosion is melt-pool boundary (MPB). The heat treatment at 940 °C demonstrates the best corrosion resistance due to the precipitation of a considerable number of needle-like and short rod-like δ phases. This indirectly reduces the dislocation density and defect density of the passivate film, resulting in improved stability and corrosion resistance.