Study On The Extrusion Formability Of Magnetic Pulse Driven Medium For 6063 Aluminum Alloy Pipe Fittings

With the increasing degree of aluminum alloy in automotive parts,aluminum alloy pipe fittings are widely used in automobile manufacturing as a typical aluminum alloy product.The aluminum alloy pipe fittings have low plasticity at room temperature and cannot meet the requirements of general aluminum alloy pipe fittings.Therefore,it is particularly important to explore new forming processes to improve the forming properties of aluminum alloys.In this paper,magnetic pulse-driven media extrusion forming combined with warm forming is used to study the bulging of magnetic pulse high-rate driving medium for the most widely used 6063 aluminum alloy pipe fittings.Through the magnetic pulse driving medium expansion molding test of 6063 aluminum alloy pipe fittings,the influencing factors of pipe formability were studied.The discharge energy is set to 5.0kJ,5.5kJ,6.0kJ and 6.5kJ.Compared with the bulging diameter,wall thickness distribution,strain and axial length of the tube under room temperature,the results show that the increase of discharge energy is beneficial to improve the bulging ability of the tube.Set the forming temperature of 25 ° C,100 ° C,150 ° C,200 ° C,compared to the bulging ability of the same discharge energy forming pipe fittings,The results show that the increase of forming temperature is beneficial to improve the plasticity of the pipe.When the pipe is at 200 °C,the bulging diameter reaches 37.1mm,the axial shrinkage is the most obvious,and the strain is also higher than the formed pipe fittings of 25°C,100°C and 150°C.A comparative test of quenching forming by quasi-static extrusion forming and magnetic pulse driving.It was found that with the increase of temperature,the bulging diameter and wall thickness reduction rate of the formed pipe fittings under both processes increased.The softening effect of the temperature on the aluminum alloy is not sufficient to offset the work hardening caused by the deformation of the pipe.Therefore,as the temperature rises,the amount of deformation increases and the hardness increases.It can be concluded from the failure strain distribution of different processes under two processes that the temperature increase can effectively improve the plastic deformation ability of aluminum alloy pipe fittings.The microstructure and fracture morphology of aluminum alloy materials were analyzed by optical microscopy and scanning electron microscopy.The microstructure evolution of magnetic pulse-driven media extrusion and quasi-static extrusion forming of 6063 aluminum alloy pipe fittings was revealed.The analysis results show that at 100 °C,with the increase of discharge energy,the magnetic pulse has a higher rate of driving to produce more slip to promote uniform deformation.A large amount of dislocation increases the density of dislocations,and the high deformation at high energy leads to the formation of fine crystal grains.The higher the discharge energy,the larger the number of fine crystal grains.When the discharge energy is 6.0kJ and the forming temperature is 200°C,the internal structure of the pipe is recrystallized under the high-speed driving of the magnetic pulse.However,due to the deformation time of the magnetic pulse driving medium forming is too short to be nucleated,the aluminum alloy crystal grains can be refined to a certain extent,the average grain size is 37.46 ?m,and the grain refinement is 44.56%.Quasi-static extrusion forming of aluminum alloy pipe fittings is quasi-cleavage fracture at room temperature.As the temperature increases,the number of dimples increases gradually.At 200 °C,the transgranular dimple breaks.The increase of temperature is beneficial to the plasticity of aluminum alloy.The rupture mode of the aluminum pulse tube driven by the magnetic pulse driving medium at 100 ° C is brittle fracture,and there is a clear cleavage step.At 200 °C,there are dimples in the fracture morphology,and the plasticity of the pipe fittings has been improved.