Research On Arc Additive Manufacturing Technology And Process Of ER5356 Aluminum Alloy

Aluminum alloy arc additive manufacturing(WAAM)has the advantages of high deposition speed and low cost,but it also has some problems such as difficult to control dimensional accuracy,high porosity and anisotropy of mechanical properties.In this paper,the CMT additive is used to manufacture thin-walled aluminum alloy parts.The parameters and images of deposition process are detected by the image acquisition system and the electrical parameter acquisition system.The forming accuracy and microstructure properties are analyzed by image processing,microscopic observation and mechanical property testing methods.The influences of travel speed Vtravel,wire feeding speed WFS,current waveform parameters(peak current Ipeak and peak current duration Tpeak)and ultrasonic vibration on the forming quality and microstructure properties of additive manufacturing were studied,so as to find new ideas and methods for improving the problems existing in CMT arc additive manufacturing of aluminum alloy.Firstly,the single-pass deposition experiment was carried out in the parameter range of wire feeding speed of 2m/min-11 m/min,walking speed of 0.15m/min and 3.0m/min to determine the matching range of wire feeding speed and walking speed that can ensure good cladding layer forming.The influence of process parameters on the forming process and the forming size of cladding layer was studied in the process of good cladding layer forming.The results show that at a certain wire feeding speed,the layer width,layer height and penetration depth decrease greatly with the increase of travel speed.With the increase of wire feeding speed,droplet transition gradually changes from CMT short circuit transition to short-circuit-droplet alternating mixed transition,and then to droplet transition,layer width and depth increase,while layer height decreases.When the peak current duration remains the same as the expert parameter,with the decrease of the peak current,the deposition speed,layer width and depth decrease,layer height increases,the droplet transition mode does not change,and the droplet transition frequency and average droplet mass do not change much.Peak current situation,experts parameters are fixed with the decrease of the peak current duration,changes in the rate of deposition,layer width and penetration decreases,and the height increases,when the peak current duration reduced to 1.2 ms,melting transition into a short circuit-shoot drops hybrid transition alternately,further reduce to 1.0 ms,drop the transition way to short circuit transfer,The droplet transition frequency decreases and the droplet average mass increases.The reduction of peak current and peak current duration can obtain a single channel cladding layer for additive manufacturing.When ultrasonic vibration is applied to induce the droplet transition from short circuit to jet,the droplet transition frequency increases and the droplet average mass decreasesAdditive manufacturing experiments were carried out in the process range of good cladding layer forming,and the effects of process parameters on the forming size,forming accuracy,porosity and microstructure properties of additive thin wall parts were studied.The results show that when the wire feeding speed is 8m/min,the average floor width and average floor height of thin-walled parts decrease when the walking speed increases from 0.6m/min to 1.5m/min.The surface roughness is greatly reduced from 1.04mm to 0.36mm,and the dimensional accuracy is improved.The porosity increases linearly.The grain size of each part decreases.When the walking speed is 0.6m/min,the average layer width increases significantly with the increase of wire feeding speed,while the average layer height also increases slightly.Porosity decreased;The interlaminar columnar grain area increases,the average grain size increases,and the transverse and longitudinal tensile strength decreases.When the wire feeding speed is 6m/min,the forming accuracy of additive manufacturing is the best.When the peak current duration is the same as the expert parameter,the average layer width and average layer height change slightly with the decrease of the peak current.Forming precision is better;With the increase of porosity,the grain size of each part decreases,and the transverse tensile strength and elongation increase.When the peak current is the same as the expert parameter,the average layer width decreases but the average layer height increases with the decrease of the peak current duration.Forming precision is better;With the increase of porosity,the grain size of each part decreases,and the longitudinal and transverse tensile strength increases.When the wire feeding speed is small(5m/min and 6m/min),the forming accuracy decreases slightly.When the wire feeding speed reaches 7m/min,the forming quality of the side wall of additive manufacturing sample becomes better.When the wire feeding speed is 8m/min,the surface roughness decreases by 52%,the dimensional accuracy reaches about 94%,and the forming accuracy improves the most.After ultrasonic vibration was applied,the total number and porosity of pores were significantly reduced.When the wire feeding speed is 7m/min,the decrease range is the largest,the total number of pores in the cross section of thin-walled parts decreases by 43%,the porosity decreases by 42%,and the large size pores basically disappear.The grains of each part were refined and the tensile strength was improved by ultrasonic vibration.With the increase of wire feeding speed,the effect of ultrasonic vibration on grain refinement becomes more obvious.When the wire feeding speed reaches 9m/min,the grain refinement effect and tensile property improvement effect of ultrasonic vibration reach the best.The results show that modified current waveform parameters and applied ultrasonic vibration in the expert parameters can obtain the additive manufacturing thin-walled parts with better forming quality and micro structure.