Laser Welding Technology And Numerical Simulation Of 6016-T4 Aluminum Alloy Plate

As a new joining technology,laser welding has the advantages of fast welding speed? small deformation and so on.It has become the most promising welding method of aluminum alloy welding.Therefore,laser welding technology has gradually become the research hotspot of automobile aluminum alloy welding.I n this paper,the 1.2mm-thick 6016-t4 automobile aluminum alloy sheet is taken as the research object.The effects of welding speed and baking on the formability and mechanical properties of laser welded joint are analyzed.The laser welding forming process and the simulation of welding joint stretch are further studied.Firstly,by using the method of controlling variables,this paper explores the change of weld pool size and weld formation of laser welded lap joints and T-joints under different welding speeds,and analyzes the influence of welding speed on the mechanical properties of lap joints and T-joints through tensile experiments.6016-t4 aluminum alloy plate is a heat-treatment strengthening alloy.In the baking process of the body coating,the mechanical properties of the welded joint will change.In this paper,the influence of baking on the performance of the welded joint is explored by simulating the temperature change process of baking in the painting workshop of a main engine factory.The results show that with the increase of welding speed,the size of weld pool becomes smaller and smaller;the joint performance is improved to some extent after baking,and before and after baking,the position of fracture failure of lap joint is at the edge of weld,and the position of fracture failure of T-joint is at the weld joint.Secondly,based on the finite element analysis software Simufact welding,this paper establishes the finite element model of laser welding lap joint and T joint,studies the temperature distribution and weld formation of laser welding lap joint and T joint under different welding speed,and verifies the reliability of laser welding process simulation through experiments.The results show that with the increase of welding speed,the distribution range of HAZ of welded joint decreases gradually,and the size of weld pool section decreases gradually;the simulation results are consistent with the experimental results,and the simulation process can reflect the temperature distribution and weld formation in the process of laser welding.Finally,the mechanical properties of the local area of the welded joint are obtained through the tensile test of the small-size specimen,and the constitutive relations and failure parameters of the base metal,the weld and the heat affected zone materials are obtained.The fine tensile simulation model of the laser welded lap joint and the T-joint is established,and the fine model of the joint is divided into grids according to the hardness curve,and th e failure mechanism of the joint is studied;Considering the calculation efficiency of simulation,the joint equivalent model which can be used in vehicle crash simulation is established,and the influence of grid size on the simulation results of the equi valent model is analyzed.The accuracy of the simulation results of the fine model and the equivalent model is verified by experiments.The results show that the fine model simulation results can better simulate the failure and stress change of the joint,the equivalent model simulation results can reflect the change of the mechanical properties of the joint,and different mesh sizes have little impact on the simulation accuracy of the equivalent model.