Microstructure and mechanical properties of NAB by wire and arc additive manufacturing

Nickel aluminum bronze alloy (NAB) is extensively utilized in the production of ship propellers because of its high corrosion resistance, resilience against biological fouling, and excellent cavitation erosion resistance in seawater. Nevertheless, conventional cast nickel aluminum bronze is no longer adequate for today's escalating demands, primarily due to its steep material cost and performance that has become outdated. To procure nickel aluminum bronze components possessing outstanding performance, wire and arc additive manufacturing technology was employed to successfully produce nickel aluminum bronze alloy components. A comparative analysis was conducted to examine the disparities in microstructure and mechanical properties between cast nickel aluminum bronze and wire and arc added nickel aluminum bronze. The findings revealed that, in contrast to as-cast nickel aluminum bronze alloy, the wire and arc added variant exhibited a refined microstructure, inhibited precipitation of the κ_Ⅰ phase, and a significant transformation of the β' phase into an eutectoid structure consisting of α + κ_Ⅲ, ultimately leading to a more homogenous distribution of elements. When juxtaposed with as-cast nickel aluminum bronze (which has a tensile strength of 545 MPa and a ductility of 20%), the wire and arc added nickel aluminum bronze components demonstrated superior mechanical properties, achieving an ultimate tensile strength of up to 700 MPa and a ductility of 38%.