The Effect On TIG Welding Arc Characteristic With Different Longitudinal Magnetic Frequency

TIG welding is widely used in nuclear power station and aerospace fields owing to itshigh performance and little splash. However, there exists penetration shallow and lowefficiency owing to arc energy decentralization and it is also influenced by the limitation ofcurrent through tungsten pole, which will limit the application on medium plate welding andhigh efficiency.It is used through adding the longitudinal magnetic into TIG arc welding processes forrealizing high efficient welding and improving welding quality, which can modify the arccharacteristics, increase the arc density of energy and enhance the weld penetration. Theinfluence of magnetic frequency in a great scale on arc characteristics is carried out in thispaper. The arc shape is taken by using high speed camera. The radial distribution of arcpressure is measured by using a self-made, water-cooled copper board as the anode. The archeat distribution is measured by using self-made circular concentric split anode device. Thecurrent density distribution is measured by using almost the same device as arc pressure test,only adding one probe in the copper board. And then having a comparison on the arc shape,arc pressure, current density and arc heat distribution, which is significant to carry out theregular pattern on the TIG welding with different magnetic frequency.It comes to the conclusion: when the welding material is copper, under the low frequencyof magnetic field, arc shape will change from cone to immersion bell. As the increase ofmagnetic frequency, the arc pressure distribution curve will change from Gaussian distributionto bimodal distribution. Under the high frequency of magnetic field, arc shape will changefrom immersion bell to cylindricality. The arc pressure in the center is much higher thantraditional arc, which has the same change features as current density. When welding currentis70A, magnetic intensity is30mT, magnetic frequency comes to1200Hz, the effect ofcompression is the most, and the arc pressure increased from0.29KPa to0.44KPa, arc heatdistribution increased from34.5%to52.9%, current density increased from18A/mm2to50.2A/mm2. There appears compression phenomenon with high frequency magnetic field.