Microstructure and cavitation erosion behavior in overlapping vs. substrate areas of WAAM NAB

This study investigated the mechanism of influence of the microstructure of nickel-aluminum bronze (NAB) alloy prepared by wire-arc additive manufacturing (WAAM) on cavitation erosion (CE) and the synergistic effect of CE and corrosion. Microstructural analysis revealed that the earlier-deposited area in the overlapping area exhibited finer grain size (6.8 µm), higher β' phase content (34.6 %), and dominant κ_Ⅲ/κ_Ⅳ precipitates, while the substrate featured coarser grain size (13.6 µm) and lower β' phase content (23.2 %) featured coarser grain size (13.6 µm) and lower β' phase content (23.2 %). CE testing indicated that in synthetic seawater, the cumulative mass loss in the overlapping area (75.2 mg) is lower than that in the substrate (82.32 mg), but the initial mass loss rate is faster. After CE, the alloy develops a 140 µm work-hardening layer, with peak hardness occurring at a depth of 20 µm. The synergistic effects of CE-corrosion accounted for 52 % of the total mass loss, with corrosion-promoted CE (34 %) exceeding CE-promoted corrosion.