Effect of Electromagnetic Stirring on Weld Solidification Structure of Aluminum Alloys (Report II) : Investigation on GTA in DCSP Weld Metal of 8mm Thick Plate

概要

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In order to investigate the effect of the electromagnetic stirring of the molten metal on the grain refinement of the solidification structure and the eliminations of the feathery crystal and porosities, GTA in DCSP bead-on-plate welding was carried out for aluminum alloys of 5083-o, 5052-o and 1070-o of 8mm thick plate as shielding gas of helium with electromagnetic stirring in the weld puddle during welding. Moreover, the application of the electromagnetic stirring to the actual welding process of square groove double butt welding with filler metal for 5083-o has been examined. Main conclusions obtained are as follows ; (1) There was the most effective frequency of alternate magnetic field for the grain refinement, that is, 2 to 15Hz. The degree of the grain refinement decreased in higher or lower frequency than the optimum frequency. (2) An increase in intensity of the magnetic field was effective to the grain refinement, but there was an limit in the intensity of the magnetic field owing to the formation of a puckering weld bead. (3) The magnetic stirring was also effective to eliminating the formation of the feathery crystal and porosities. (4) The electromagnetic stirring remarkably increased the soundness of the butt welds of 5083-o with filler metal by suppressing the formation of the feathery crystal and large porosities and also refining the grains.
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