Finite Element Analysis And Process Research On Aluminum Alloy Arc Additive Manufacturing Based On CMT

Additive manufacturing technology is a kind of manufacturing technology that accumulates materials from bottom to top and quickly and accurately realizes the components from nothing.With short processing cycle and low manufacturing cost,additive manufacturing technology is especially suitable for the production of small batches of parts.Cold metal transition technology is a low heat input welding method that combines high frequency varying welding current with rapid wire withdrawal.The application of cold metal transition technology for additive has the advantages of low heat input,less splash and stable additive process.In this paper,we use CMT technology to manufacture aluminum alloy thin-wall member with 5183 aluminum alloy welding wire as filler material on the aluminum alloy substrate with thickness of6 mm,establish finite element model to simulate the temperature field of the member,and conduct experiments on the basis of simulation results to study the structure and performance of the member.It is of theoretical guiding significance for the actual production of aluminium alloy material addition.Based on the previous experiments,the model is established,and the heat source is loaded in the numerical simulation by programming in Fortran language.The accuracy of the model is verified by thermocouple temperature measurement and the results of temperature field distribution are calculated.The results show that the simulated thermal cycle curve fits well with the actual measurement curve.Deposition layer will be subjected to multiple thermal effects under the influence of subsequent load heat source.Peak temperature of molten pool increases with the increase of layer height and there will be severe heat accumulation at the arc-ending end.In this paper,by changing the process parameters of the model,the influence mechanism of different factors on the temperature field is explored.It is found that the cross-adding path can make the temperature distribution of components more uniform and effectively reduce the heat accumulated at the arc-closing end.Extending the interlayer cooling time can effectively reduce the overall temperature and temperature gradient of the component.Properly accelerating the wire feeding speed can reduce the temperature gradient in the component,and excessively accelerating the wire feeding speed will increase the temperature gradient.The higher the welding speed,the lower the peak temperature and residual temperature of the deposit layer,but the welding speed has less influence on the deposit layer than the wire feed speed.Preheating the substrate has a great influence on the first four deposits.Additional material manufacturing experiments are carried out based on the simulation results to study the structure and performance of components.It is found that when welding speed is 450 mm/min and wire feed speed is 5.0 m/min,the forming precision of thin-wall body reaches 98.16%.The increase of welding speed and wire feed speed will result in the increase of pore size and number in the component.The grains near the fusion line at the top of the member are mainly cylindrical grains and the grains near the fusion line at the middle are equiaxed grains.Tensile tests were carried out on the members.The overall tensile properties of the thin-walled body formed at welding speed of 450 mm/min and wire feeding speed of 5.0 m/min are the best.Its transverse tensile strength is 261 MPa and longitudinal tensile strength is 273 MPa.The fracture form of the tensile fracture is ductile-brittle mixed fracture.