Numerical Simulation Of Welding Temperature Field And Residual Stress Of Dissimilar Aluminum Alloy Composite Heat Source

The welded structure of dissimilar aluminum alloys is applied to various industries because of its comprehensive properties and wide adaptability.Due to the high thermal conductivity,electrical conductivity and thermal expansion coefficient of aluminum alloys,it is easy to cause various problems and seriously affects the performance.The traditional welding method is not suitable for welding dissimilar aluminum alloys,but the laser-arc hybrid welding can better solve the above problems.At present,the research on laser-arc hybrid welding of dissimilar alloys mostly appears in the aspects of organization and performance at home and abroad.However,due to the limitations of test conditions and methods,there are few studies on residual stress and deformation.Through the numerical simulation method,the evolution of the temperature field,stress field and deformation during the laser-arc hybrid welding of dissimilar aluminum alloys can be fully understood and it provides theoretical support for the reduction of residual stress and the control of residual deformation,which has important engineering application value.This paper simulates and validates the laser-arc hybrid welding of 6mm thick 6063/5083 dissimilar aluminum alloy plate based on Simufact.Welding(SW).The dynamic changes of the temperature field,stress field and the post-weld deformation under 3 different welding speed were analyzed and compared.Using SW,taking into account the clamp clamping state,pre-heating before welding,post-weld heat treatment,calculate the changes of the stress and deformation.The residual stress and deformation under different process conditions were calculated and predicted.The verification test results show that the simulation results are in good agreement with the test results under the premise of ensuring the accuracy of the heat source calibration.The simulation results have high reliability.In the welding stage,the distribution of the temperature field is semi-elliptically asymmetrical with the welding line,and the pool width increases and high temperature area expands with the decrease of welding speed.In the cooling stage,the welding fixture causes differences in the cooling rate of the upper and lower surfaces of the workpiece,and a low temperature area was showed obviously on the upper surface.Stress field and deformation simulation results show that,in the welding stage,the Von-mises equivalent stress of the parent metal on both sides presents an asymmetrical elliptical distribution.In the cooling stage,the stress on the 5083 aluminum alloy and the welding line is significantly increased,and the maximum stress is located at the welding line.The decrease of the welding speed increases the stress on the 5083 aluminum alloy but has little effect on welding line.Along the direction of the welding,the longitudinal and transverse residual stresses of parent metal on both sides are mainly tensile stress.The longitudinal residual stress decreases and the transverse residual stress increases with the decrease of welding speed;vertical to the direction of the welding line,from the welding line to the parent metal,the distribution of the longitudinal residual stress and the transverse residual stress is complex,with the decrease of welding speed,the effect on the stress change is different.The deformation of the workpiece is small.The deformation is mainly the transverse shrinkage and the deformation mainly exists on the welding line and 6063 aluminum alloy,and the welding speed has little effect on the deformation.The simulation results under different process conditions show that the unloading of the welding fixture at suitable time is conducive to the reduction of the residual stress,but it will cause angular deformation of the workpiece.Appropriately increasing the preheating temperature has a positive effect on reducing the residual stress of the parent metal,yet that of the welding line will not.However,excessive preheating temperature will increase the transverse shrinkage of the workpiece.Annealing temperature mainly affects the heating rate of the workpiece,and the residual stress of welding line and transverse shrinkage significantly decreases after annealing.Excessively high annealing temperature and long holding time have no positive effect on the residual stress of welding line,and.cause longitudinal expansion of the workpiece.