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Electromagnetic stirring in MIG welding of aluminium

  • Auerkari, Pertti
  • Harju, Mikko
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VTT Publications Register


Brittleness caused by coarse microstructures and porosity in TIG welds of aluminium alloys can be suppressed if electromagnetic stirring (EMS) of the weld pool is applied. However, practical industrial examples of using EMS in welding are rare because both the equipment and the welding methods have not been devoted for ordinary welding purposes. In this study the possibilities of EMS in MIG welding of aluminium alloys have been cnnsidered. A simple coil has been attached to a MIG torch and fed by a pulsating welding current supply. Especially the effect of EMS to porosity of aluminium welds has been investigated. For comparison also some results of corresponding MIG weld tests with a commercial magnetic arc deflecting device are given. The EMS was effective in avoiding excess porosity in aluminium MIG welds: acceptable porosity levels were possible even with an Ar + 5 % H2 shielding gas. The dimensions of a sufficient coil for producing EMS were shown to be reasonable for practical welding. The magnetic arc deflecting device was shown to be useful in welding on dirty surfaces. Even high deflecting amplitudes causing spatter do not detrimentally increase the turbulence of the shielding gas flow.

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