Effect of Pre-Set Coating Thickness on the Quality of Electron Beam Cladding Forming of Aluminum Alloys

Numerical simulations combined with electron beam melting were adopted to study the effect of the thickness of the preset coating on the quality of electron beam melting and forming of aluminum alloys. The research was carried out using ANSYS19.0 finite element analysis software to perform the numerical simulation of the temperature field and stress field during the process of electron beam melting of the Ni60 coating on 6061 aluminum alloy. The results show that the thicker the preset coating, the higher the surface temperature and the greater the melting depth and width of the melt pool, but the smaller the substrate melting depth, and the highest surface temperature obtained was 2536.05 °C. When the coating thickness reached 1.5 mm, the substrate essentially showed no change; otherwise, the thicker the preset coating, the greater the residual stress, and the maximum residual stress on the coating surface along the scanning direction appeared at the position near the boundary. Moreover, the maximum residual stress along the depth direction occurred at the interface. The electron beam cladding experiments showed that the 0.5 mm thickness of the coating resulted in a cracking phenomenon at the interface with the substrate, and the surface of the molten layer had more defects such as pores and pits; the 1 mm thickness of the coating had a good metallurgical bond with the substrate, and the surface of the molten layer was dense and flat; the 1.5 mm thickness of the aluminum alloy substrate did not melt, and the surface of the molten layer had more cracks. The numerical simulation was essentially consistent with the electron beam cladding experiment, and the forming quality was better when the preset coating thickness was 1 mm.