Effect of Arc-Ultrasonic Coupled Waveform on MIG Weld Forming,Microstructure and Properties of Aluminum Alloy
Ultrasonic can be introduced into the welding process by coupling the ultrasonic frequency pulse electrical signal to the DC MIG welding signal.Three different coupling waveforms were obtained by changing the parameters of coupling capacitance.The effects of arc ultrasonic coupling waveform on the weld appearance,microstructure and mechanical properties of aluminum alloy were studied by means of ultra-depth of field 3D digital microscope,scanning electron microscope and automatic hardness tester.The results show that when the coupling waveform corresponding to the capacitance of 0.033 µF is used for welding,the weld appearance is the best,the weld porosity is the lowest,and the joint hardness in each area is higher than that of the other two waveforms.The basic reason for the improvement of welding quality is that the coupling waveform corresponding to the capacitance of 0.033 µF has the minimum supplementary heating input.Reasonable coupling waveform can obviously inhibit the precipitation of the second phase in the weld zone and the fusion zone,while arc ultrasound promotes the precipitation of the second phase in the heat affected zone,and the area proportion of the second phase in the heat affected zone increases.
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