Study On Process,Microstructure And Properties Of Aluminum Bronze Alloy By Laser Additive Manufacturing

The additive manufacturing of ship propellers is an effective way to shorten the maintenance period of ships,reduce the risk of incapacitation,and improve the compatibility of ship-machine-propeller and its propulsion efficiency.The existing laser fuse additive technique overcomes the application limitations of copper alloy materials such as high thermal conductivity,low laser absorption rate,and large thermal stress,and effectively solves the irreconcilable problems such as local shrinkage porosity,particle inclusion and shrinkage cavity defects of traditional sand casting nickel-aluminum bronze structural parts.In this thesis,multi-type additive parts were prepared through a large industrial laser fuse platform by using two industrial aluminum bronze wires,SCu6240 and SCu6328chosen as additive materials.The influence of process parameters on the forming state of copper alloys was analyzed to seek the best deposition parameter.Multivariate performance tests were carried out to analyze the influence mechanism of structure state and characteristics,and precipitated phase behavior on the anisotropic mechanical properties of the material.The influence of heat treatment regime on the thermal stability and corrosion resistance of the additive was also evaluated.Thus,it provided experimental references for the industrialization of wire-deposited aluminum bronze propeller components.For SCu6240 as the deposition material,the effect of laser process parameters on the single-channel single-layer macroscopic morphology and size of a single layer was studied.The results show that low laser power,low scanning speeds,and high wire speed forming are superior.The effects of different scanning speed on the microstructure and mechanical properties of single-channel multi-layer thin-walled parts were studied after optimizing the parameters by orthogonal experiment.The results show that the microstructure of high-scanning speed thin-walled parts is more refined,and the yield strength,tensile strength and elongation are increased by 7.1%,9.3%and 12.9%,respectively.For SCu6328 as the deposition material,the effect of laser process parameters on the single-channel single-layer macroscopic morphology and size was studied.The results show that a single layer can be formed under the condition of changing laser power,scanning speed and wire speed.The effects of different scanning speed on the microstructure and mechanical properties of single-channel multi-layer thin-walled parts were investigated after optimization of orthogonal experimental parameters.The results show that the microstructure is composed ofα,β′andκphases.The structure of 7mm/s thin-walled parts is more refined,and the yield strength,tensile strength,and elongation are increased by 6.0%,0.6%,and 5.9%,respectively.The multi-channel and multi-layer results show that the mechanical properties of the samples parallel to the deposition direction are better than those perpendicular to the deposition direction,which illustrates that the material is anisotropic.Compared with SCu6240 single-channel multi-layer thin-walled parts,the research shows that SCu6328 alloy has better forming quality and comprehensive mechanical properties.The study on microstructure stability and corrosion resistance of SCu6328 alloy after heat treatment shows that 800℃normalizing and aging reduce the corrosion rate of SCu6328 nickel aluminum bronze alloy from 0.0512mm·a^-1to 0.0485mm/a and0.0503mm/a at 31℃。...