Title : Study on Mechanical Properties of Copper Alloy CuNi2SiCr Layered on Nickel Aluminum Bronze NAB by Using Direct Energy Deposition
Abstract:
Nickel aluminum bronze (NAB) is widely used to fabricate marine propellers owing to its excellent corrosion resistance in sea water. The repair process of damaged propellers is an important research topic. This research proposes a repair method in which metal additive manufacturing (AM) technique is employed, not the conventional welding. Of various metal AM technologies, we studies direct energy deposition (DED) which can be useful for repairing of a damaged component. The DED process uses high-power lasers to melt metal powder and then solidify it on the site to be repaired to achieve the repair of damaged parts. For repairing NAB substrate, CuNi2SiCr powder was used. Thus, this study focused on the mechanical properties of CuNi2SiCr deposited on the NAB substrate through DED. First of all, the optimal process parameters of the DED process were established by trying different laser power, powder feed rates, scanning speed, coaxial gas flows and powder gas flows rate. In addition, the mechanical properties of the deposited and substrate were studied through microhardness measurement, tensile test and Charpy impact test. The results show that the microstructure of the deposited layers is α-Cu, which shows the characteristics of low strength, hardness and high toughness. The microstructure of NAB substrate exhibits higher hardness and strength and lower toughness than the deposited CuNi2SiCr, since the substrate was composed of typical α + β solid solution and different intermetallic κ phases. Moreover, the tensile strength and elongation of the deposited specimens are lower than those of the substrate because the deposition layers have micropores. This study indicates that copper alloy CuNi2SiCr is deposited by DED, which provides a new idea for repairing NAB parts through metal additive manufacturing. The future research includes the methods for avoiding the internal porosity and enhancing its strength and hardness of the deposited part.
What will audience learn from your presentation?
- Copper alloy CuNi2SiCr powder can be deposited by direct energy deposition.
- The pores generated in the deposited region degraded its strength and toughness.
- The hardness and strength owing to α phase formed in the deposited copper alloy are lower than those of the substrate, but the toughness is higher than that of the substrate.
- The microstructure of the deposited part is mainly composed of α-Cu phase, which led to more excellent impact performance and toughness compared with NAB substrate.
