This study electroplates a 2 μm thick Al layer on mild steel, then uses wire-arc directed energy deposition (DED) to deposit Cu-4.2Sn alloy, forming a composite material which is subsequently cold-rolled. It investigates the microstructure, mechanical properties, and tribological behavior before and after rolling, along with underlying mechanisms. It indicates that Al coating completely suppresses penetration cracks on the steel side of the tin bronze/steel bimetal. After rolling, tin bronze grains are significantly refined (from 47.6 μm to 15.2 μm) with numerous twins formed, reducing matrix dislocation density. Compared to wire-arc DED alloy, rolled alloy hardness increases by 78%, yield strength by 51%, and tensile strength by 30%. Tribological tests indicate, under dry friction and simulated seawater conditions, the rolled alloy’s coefficient of friction (COF) and mass loss decrease by 30% and 24% respectively. Analysis of corrosion-friction synergy reveals interaction loss accounts for 13%, dominated by friction-promoted corrosion (11%).

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.