A study on mechanical properties of CuNi2SiCr layered on nickel–aluminum bronze via directed energy deposition

Abstract

Nickel-aluminum bronze (NAB) is a widely used copper alloy for the fabrication of marine propellers owing to its excellent corrosion resistance in seawater. The repairing process of damaged propellers is an important research topic. This study proposes a repair method that employs the directed energy deposition (DED) technique and copper alloy powder (CuNi2SiCr). This study focused on and mechanical properties of CuNi2SiCr deposited on an NAB substrate through DED. First, the optimal process parameters of the DED process were established by varying the laser power, powder feed rate, scanning speed, coaxial gas flow, and powder gas flow rate. In addition, the mechanical properties of the deposited material and substrate were studied through microhardness measurements and mechanical tests. The results showed that the microstructure of the deposited layers was α-Cu, characterized by low strength, hardness and high toughness. The microstructure of the NAB substrate exhibited higher hardness and strength than the deposited CuNi2SiCr, because the substrate was composed of a typical α + β solid solution and different intermetallic κ phases. Moreover, the tensile strength and elongation of the deposited specimens were lower than those of the substrate because the deposition layers have micropores. The wear resistance of the deposited specimens was lower than that of NAB owing to low hardness and plastic deformation during wear. This study demonstrates the feasibility of the DED deposition of copper alloy—CuNi2SiCr—and proposes a novel method that repairs NAB parts using the metal additive manufacturing process.

Keywords

• Directed energy deposition
• Nickel-aluminum bronze
• Microstructures
• Mechanical properties