Interfacial Behavior and Properties of Aluminum-Bronze Coatings on Ductile Iron by Wire-Arc Deposition

Aluminum-bronze coatings are successfully prepared on ductile iron by cold metal transfer (CMT) wire-arc deposition. Interface characteristics and properties of aluminum-bronze coatings on ductile iron are investigated. The results demonstrate that heat input not only has a significant effect on the dilution rate, but also can affect the microstructure evolution and interface behavior. At low heat input, the dilution rate is close to zero, and incompletely dissolved graphite nodules and a few short cracks are distributed on the fusion line. The gamma(2) + alpha-Cu eutectic phase is produced along the columnar grain boundaries of the deposited layer, and no Fe-enriched phase is found. As heat input increases, the interface between aluminum bronze and cast iron changes from a diffusion joint to a metallurgical bond and from a single interface to a double interface. Fe-enriched phases and Cu-enriched phases are produced in the deposited layer and fusion zone, respectively. The microstructure of the fusion zone is mainly austenite, martensite, and ledeburite, resulting in the highest hardness near the interface. The interfacial bond strength of high heat input deposited layer is significantly higher than that of low heat input, and the latter has higher wear resistance than the former.