Reserch On Process And Microstructure Properties Of 4043 Aluminium Alloy Manufactured By Ultrasonic Assisted CMT-Pulse Advanced Arc Additive Manufacturing

Wire arc additive manufacturing(WAAM)has the advantages of high material deposition efficiency and utilization rate,the ability to manufacture large size components,low production cost,but also has the problems of low dimensional accuracy of the formed parts,porosity defects,large deformation of the formed parts,low mechanical properties and so on.In the paper,CMT-Pulse advanced arc mode is used to fabricate aluminum alloy thin-walled parts.The electrical parameters and droplet transition images in the process of deposition were obtained by using a synchronous acquisition system of electrical parameters and high-speed photography.The forming accuracy of thin-walled parts was analyzed by using graphics processing software.The microstructure properties of thin-walled parts were analyzed by means of microscopic observation and tensile property testing.The effects of traveling speed,wire feed speed,inter-layer temperature,polarity ratio and ultrasonic vibration on the forming quality,microstructure and properties of wire arc additive manufacturing of aluminum alloy were studied to find a new method to solve the problems existing in the process of wire arc additive manufacturing of aluminum alloy.First of all,the single-channel deposit experiments were performed with the scope of wire feed speed of 3 m/min～10 m/min and traveling speed of 0.15 m/min～1.65 m/min,and the process range of wire feed speed and traveling speed of well-formed deposition was obtained.The influences of traveling speed,wire feed speed,EP/EN-Balance parameter value and ultrasonic vibration on single-pass depositing process and single-pass deposition forming size were investigated in the process range of well-formed deposition.The results show that when the wire feed speed is constant,the height,width and penetration all reduce with the improve of the traveling speed.When the traveling speed is constant,the height,width and penetration increase with the increase of wire feed speed.When the wire feed speed and traveling speed are unchanged,with the increase of EP/EN-Balance parameter value,the layer width and depth increase while the layer height decreases.The deposition which is conducive to additive manufacturing can be obtained by reducing the EP/EN-Balance parameter appropriately.In CMT-pulse advanced mode,the droplet transition mode of ER4043 aluminum alloy is not affected by the process parameters,and the Pulse period of EP phase is "one drop",while the CMT period of EN phase is short circuit.The application of ultrasonic vibration can promote the short circuit transition and shorten the short circuit duration.The additive manufacturing experiments were performed with the process scope of wellformed single-channel deposition,and the effects of traveling speed,wire feed speed,interlayer temperature,polarity ratio and ultrasonic vibration on the forming,microstructure and properties of thin-walled forming parts were studied.The results show that when the wire feed speed is constant,with the traveling speed increasing from 0.6 m/min to 0.9 m/min,the average height and average width of the thin-walled forming parts decrease,the surface roughness decreases first and then increases,the dimensional accuracy increases first and then decreases,the porosity increases approximately linearly,and the grain size of each part decreases,the tensile strength and elongation increase first and then decrease.When the traveling speed is constant,with the wire feed speed increasing from 6m/min to 9m/min,the average height and average width of the thin-walled forming parts increases,the surface roughness increases,the dimensional accuracy decreases,the grain size of each part increases,and the tensile strength and elongation show a downward trend on the whole.When the traveling speed and wire feed speed are constant,the inter-layer temperature increasing from 70℃ to 110℃,the average width of the deposition increases and the average height of the deposition decreases,the surface roughness increases,the dimensional accuracy decreases,the grain size of each part increases,and the tensile strength and elongation show a downward trend.When the traveling speed and wire feed speed are constant,with the EP/EN-Balance parameter value increasing from-1 to 2,the average width of the deposition increases while the average height of the deposition decreases,the surface roughness increases continuously,the dimensional accuracy decreases continuously,the porosity decreases significantly,the grain size of each part increases,and the tensile strength and elongation decrease first and then increase.After ultrasonic vibration was applied,the average width and average height of deposition did not change much,the surface roughness was reduced,the dimensional accuracy was increased,the porosity decreased obviously,the grains of each part were refined,and the strength of tension and rate of elongation were increased.When the wire feed speed was 6 m/min and the traveling speed was 0.9 m/min,the number of pores decreased the most after applying ultrasonic vibration,which was reduced by about 68%.When the wire feed speed was 9 m/min and the traveling speed was 0.6 m/min,the grain size and tensile properties changed the most.The average diameter of the top grain decreased by 8.9%,the average diameter of the interlayer grain decreased by 6.6%,and the average diameter of the intra-layer grain reduced by 23.5%.The transverse strength of tension is improved by 6.4%,the transverse rate of elongation is improved by 37.2%,the longitudinal strength of tension is improved by 5.8%,and the longitudinal rate of elongation is improved by 25.3%.The results show that the forming quality,microstructure and properties of additive thinwalled forming parts can be improved by modifying the polarity ratio and applying ultrasonic vibration.