Formation and effect of hierarchical structures on corrosion performance of stainless steel bipolar plate fabricated by powder bed fusion

Thin-walled stainless steel (SS) bipolar plate (BP) with a star-shape flow field was fabricated by powder bed fusion (PBF). The full-scaled microstructure analysis was carried out to explore the relationship of cooling rate with the morphology evolution. The high cooling rate results in special nanotwins and stacking faults, together with different types of nano-inclusions. The printed PBFed samples deliver excellent corrosion resistance , surface conductivity and hydrophobicity in the simulated environment of proton-exchange membrane fuel cell. The enhanced corrosion resistance can be attributed to the thicker passivation film promoted by the ultra-fined grains, nano-scaled cluster cells, and nanotwins.