电弧超声耦合波形对铝合金MIG焊缝成形、组织及性能的影响

Effect of Arc-Ultrasonic Coupled Waveform on MIG Weld Forming,Microstructure and Properties of Aluminum Alloy

通过超声频脉冲电信号与直流MIG焊接电信号耦合,可将超声引入焊接过程。通过改变耦合电容参数获得三种不同的耦合波形,采用超景深三维数码显微镜、扫描电镜及全自动硬度计等分析测试手段,研究了电弧超声耦合波形对铝合金焊缝成形、组织及力学性能的影响。结果表明:采用电容为0.033μF所获得的耦合波形进行焊接时,焊缝成形最佳,焊缝气孔率最低,接头各区域硬度高于利用另外两种波形焊接得到的接头硬度。分析认为,焊接质量改善的根本原因在于电容为0.033μF所对应耦合波形的附加热输入最小。合理的耦合波形可以明显抑制焊缝区与熔合区中第二相的析出,但电弧超声反而会促进热影响区内第二相的析出,导致热影响区的第二相面积占比增大。

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 0.033μF 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 0.033μF 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.