Process Research And Numerical Simulation Of Inconel718 Alloy Electron Beam Cladding With Protective Coating

Nickel-based alloys are widely used in the hot end parts of aero-engines because of their excellent comprehensive properties.With the rapid iteration of engines with high thruster weight ratio and high flow ratio in aerospace field,the inlet temperature of the turbine is constantly increasing,which puts forward higher requirements on the performance of Inconel718 alloy used.However,Inconel718 alloy contains a variety of active elements,its surface is more prone to oxidation at high temperatures.In order to ensure the long-term stable operation of the equipment and the sustainable development of the new aerospace engine,it is critically important to improve the high temperature resistance,oxidation resistance and corrosion resistance of Inconel718.In this paper,a functional protective coating was applied on Inconel718 alloy surface by electron beam cladding technique to improve the performance of the alloy to cope with the harsh service environment.Electron beam cladding is characterized by local heating and rapid solidification and cooling,so it is inevitable to produce stress in the cladding process,cladding technology is the key to ensure the quality of cladding layer.Therefore,the finite element numerical simulation method was used to simulate the thermal action in the process of electron beam cladding and to explore the influence law of process parameters on the distribution of temperature field and stress field,so as to provide theoretical support for the optimization of process parameters and the prediction of prevention and control of cladding layer defects,and guide the actual process to obtain the cladding layer with excellent performance.After the preset stacking model of coating powder was established,the stress analysis and calculation were carried out,which provided theoretical guidance for the collocation and selection of powder coating.The minimum conditions of electron beam cladding were determined by calculating the temperature rise of powder heating.Ni Co Cr Al Y powder and Zr O₂-Ni Co Cr Al Y powder were selected as the protective coatings for this study when optimizing the design of the coatingUsing ANSYS finite element software established Inconel718 alloy electron beam cladding protective coating the surface of the heat transfer analysis and thermodynamic coupling model,The paper analyzes the temperature field and stress field of the cladding process change law with time,the influence of different process parameters on the distribution of temperature field and stress field is discussed,and the typical path on the temperature and stress were studied.The results show that the maximum instantaneous temperature is directly proportional to the electron beam power when the scanning speed and the spot diameter are constant,and the larger the spot diameter and the scanning speed,the lower the peak temperature.The residual stress increases with the increase of electron beam current and scanning speed and the decrease of beam spot diameter.Most of the cladding areas are dominated by tensile stress,and theis always tensile stress along the electron beam scanning direction.The tension stress relationship along the vertical electron beam scanning direction is>>,and the coating is greater than the interface;The peak value ofalong the depth direction appears at the interface between the cladding layer and the matrix,which is a place prone to deformation and cracking.On the basis of numerical simulation,the cladding samples were prepared by the optimized process parameters,and the morphology and phase composition of the cladding layers were characterized and analyzed by scanning electron microscopy（SEM）,energy dispersive spectroscopy（EDS）,optical microscopy（OM）and X-ray diffraction（XRD）.The static oxidation resistance of Inconel718 alloy substrate and Ni Co Cr Al Y coating at 900℃was tested.The results show that the microstructure of the coating after electron beam cladding is compact,and the element interdiffusion between the cladding layer and the substrate forms a good metallurgical bonding in the fusion zone.The simulated results are in good agreement with the experimental results.After electron beam cladding,the oxidation resistance of Ni Co Cr Al Y coating is 24.91%higher than that of thermal spraying coating,and 66.8%higher than that of substrate.The surface of Zr O₂-Ni Co Cr Al Y cladding layer is relatively dense in high temperature molten salt environment.It is proved that electron beam cladding technology can greatly improve the properties of materials.