Three-Dimensional Numerical Simulation And Analysis Of Temperature Field And Stress Field In Metal Welding Deposition Prototyping

As a great breakthrough in manufacture field,metal welding deposition prototyping has aroused wide concern.It has the advantages of high molding efficiency,low production cost and flexible depositing paths.What’s more,the microstructure of metal parts is compact and the mechanical properties are good.However,the temperature are changed sharply in the forming process.Inter-layer stresses and metallurgical bonding strength are influenced by multiple heating.As a result,residual stresses analysis and deformation prediction are difficult.In this paper,a single pass multilayer model is built.GMAW arc is used as welding heat source and metal welding wire is used as filling material.Numerical simulation results of temperature,stress and deformation field are obtained and influence factors in the molding process are analysed and studied.Temperature,stress and deformation field of 10-layer single-pass deposition are obtained through simulation.Shape parameter of welding pool and heat accumulation in the process of deposition can be seen from temperature nephogram.Temperature gradient and rate are obtained by thermal cycling curve of different parts.An infrared thermal imager experiment is conducted to verify the temperature field of welding process.The welding pool morphology,heat affected zone and thermal cycling curve are identical with those in the simulation.The correct check of heat source model and cooling coefficient are proven.Evolution process of interlaminar stress and deformation regularity are studied.The influence of the rear layer on the stress of the fore layer is analyzed.The main parts and deformation tendency of residual deformation after welding are obtained.Based on numerical simulation results,combined with experiments,influence factors of deposition process are researched.Results show that the longitudinal tensile stress of melt zone decreases and the transverse tensile stress increases with the decrease of welding speed.Particularly,residual stresses at the ending arc decrease obviously with the decrease of welding speed.So a slow welding speed can be set at the ending arc.The inter-layer idle time is necessary among the deposition process to avoid the component over-heating resulting in bad forming.Residual deformation has the tendency of decrease with the increase of inter-layer idle time.Inter-layer idle time has little effect on stress.Residual stresses are greatly reduced with the deposition of alternating direction.Deformation at starting arc and ending arc is also reduced with this depositing path.Quality of parts is very good under deposition of alternating direction.Welding deformation is affected by the number of constraint and the position of constraint.The quality of depositing parts can be improved by reasonable layout of constraints.