Research On Magnetic Field Assisted MIG Welding Process Of Dissimilar Aluminum Alloy And Weld Performance

Aluminum alloys have been widely used in various vehicle bodies and their accessories.In industrial production,it is necessary to weld dissimilar aluminum alloys to meet the requirements of working environment and conditions.MIG welding is commonly used for aluminum alloy welding,but welding defects such as blowholes,coarse grains,and thermal cracks may occur during the welding process.Therefore,this paper introduces a longitudinal magnetic field method to reduce welding defects and improve weld performance.In this paper,the external longitudinal magnetic field assisted MIG welding was used to perform welding test on 5083/6061 heterogeneous aluminum alloys.The welding current in the absence of magnetic field was studied by high-speed camera shooting,metallographic structure analysis,scanning electron microscope detection,X-ray diffraction,and mechanical property testing.The effects of welding speed and other parameters on the weld formation and the mechanical properties of the welded joint,and on this basis,the different excitation currents and excitation frequencies of the alternating longitudinal magnetic field were studied on the welding arc and droplet transition in the welding process of 5083/6061 heterogeneous aluminum alloys.The effect of different excitation currents and excitation frequencies from the longitudinal magnetic field on the weld formation,microstructure,and mechanical properties such as microhardness,tensile strength,and elongation of the welded joint.Welding parameters The welding current is set to 9mm / s,the welding current is 163 A,the welding seam is better formed when the welding voltage is 19.4V,the tensile strength173.25 MPa elongation 11.3% is better than other welding parameters.In the absence of a longitudinal magnetic field,the welding arc shape is similar to "conical" during the welding process.The arc is relatively stable,with less spatter,the shape of the droplet is positive,the fish scale on the weld is more uniform but sparse and uneven,and the weld area is a branch There are columnar crystals in the fusion zone,the grains are thick,there is no obvious fusion line on the 5083 side,and the organization on both sides of the fusion line on the 6061 side is clear.When the longitudinal magnetic field is introduced,as the strength of the magnetic field becomes larger,the shape of the welding arc gradually changes to "bell-shaped",expanding first and then contracting.When the excitation current is 2A and the excitation frequency is 65 Hz,the arc is more stable during welding,and the arc shape is the most full.As the strength of the magnetic field becomes larger,the shape of the droplet transition gradually changes to an ellipsoid shape,and the time taken for the droplet transition to decrease first and then increase.The shortest time for the droplet transition at2A65Hz;the melt width increases first and then decreases as the magnetic field parameter becomes larger.At 2A65 Hz,the surface texture is clear and dense,the melt width is widest,and there is very little splash.After the longitudinal magnetic field is added,the dendrites in the weld zone are refined,and the columnar crystals in the fusion zone are reduced.The grain refinement is most significant at 2A65 Hz.At this time,the second phase Mg2 Si is more uniformly and finely affected by electromagnetic stirring;the fractured tough densities are at 2A65 Hz More and more uniform,the tensile strength is increased by 28 MPa compared with no external magnetic field,and the microhardness of the weld is increased by 11 HV.At this time,the mechanical properties are the best.When the welding parameter welding current is set to 9mm / s,the welding current is163 A,the longitudinal magnetic field parameter is set to the excitation current of 2A,and the excitation frequency is 65 Hz,the longitudinal magnetic field can better match the MIG welding to achieve the effect of reducing welding defects and optimizing performance.