Electromagnetic Welding of Aluminum Tube with Aluminum—and Dissimilar Metal Cores

Studies on Electromagentic Welding (Report 1)

Abstract

The electromagnetic force was applied for welding aluminum tubes. The main part of the welding equipment was the condenser of total capacitance of 800μF and the maximum charge voltage of 5 kV. Coils of 10 to 15 turns were attached around the tubes. The test specimens were the couples of aluminum tubes and core bars of similar or dissimilar metals and alloys. Both the tapered and straight cores weree used.
The welded joints were examined by peel test and also by microscopic observation on the cross-section.
Annealed aluminum tubes of 15 mm in diameter and the maximum thickness of 1 mm could be welded with the cores at the minimum current of 60 kA. Both the specimens of tapered and straight cores could be welded. The clearances of 1.0 to 1.5 mm were usually necessary between tube and straight core; no successful results could be obtained without clearance. A taper of about 8 degrees was suitable for the tapered core.
Cores of mild steel, carbon steel, cast iron, copper, titanium, molybdenum as well as aluminum and its alloy could be welded with aluminum tubes. Although intermetallic compound layers were produced at the interface of welded zones as in the case of other welding processes, the thickness of the layers were very small as 2 to 20 μm.
The wavy patterns were observed at the interface of welded zones, which were similar with those observed in explosive welding. And it is considered that such the patterns were produced by the high velocity collision between tube and core.