Finite Element Analysis Of CMT Welding Process Of Aluminum Alloy Sheet

Cold metal transfer(CMT)is a new type of gas metal arc welding technology with the advantages of low heat input,no welding spatter.It is a feasible method for welding thin plate and dissimilar metals.In this paper,CMT technology was used to weld 5052 aluminum alloy sheet,and the microstructure and properties of welded joints were analyzed.Based on heat transfer and thermo-elastic-plastic finite element analysis theory,a 3D numerical model was established using ANSYS 15.0 for studying the CMT welding process of aluminum alloy sheet,which has practical significance for numerical simulation and application of CMT technology.Firstly,different welding parameters were used in the welding experiment,and rational process parameters were determined.The microstructure of weld joint was analyzed.Equiaxed dendrite with fine grain size was observed in weld center,and columnar grain structure was observed near the fusion line.The microhardness of weld joints was measured,and the softening of heat-affected zone was observed.The tensile properties of weld joints were tested,and the fracture position is located in the heataffected zone.The maximum tensile strength of weld joints is 200.1 MPa.In the study of numerical simulation,the thermal analysis model was established and meshed.The moving Gaussian heat source model was employed in the present study to simulate the CMT welding process.In order to realize the periodic loading of welding heat source and reflect the "cold-hot-cold" characteristics of CMT welding process,APDL was used to compile heat source loading commands.The thermal analysis model was validated using the experimental results.According to the results,the characteristics of CMT welding temperature field were analyzed,and the influence of welding parameters on the thermal field was analyzed.The transient thermal analysis results were used as the input in the structural analysis.The transient stress,residual stress and welding deformation of CMT welding were analyzed by sequence coupling technology.According to the results,the distribution of stress and deformation at different moments were analyzed,and the influence of welding parameters on residual stress and welding deformation was studied.The simulation result shows that post-weld heat treatment can significantly reduce the welding residual stress.