Interfacial Observation of Parallel Seam Welded-Aluminum Sheets by Magnetic Pulse Welding Method with Collision between Metal Jets

Abstract

This paper describes the parallel seam welding of aluminum sheets by a magnetic pulse welding method with a flat one-turn coil. The coil has a narrow central part and this part has two parallel upper parts. A discharge current from a capacitor bank flows along these parts. A magnetic flux having two high-density peaks is suddenly generated around these parts. The flux intersects the sheets which are overlapped on the coil. The resulting eddy currents are induced in the sheets, applying two parallel strong electromagnetic forces to them. The sheets with a gap collide with each other at high speed on two parallel places, and are welded. In this time, four metal jets occur just ahead of the collision front and four weld zones are made. Two metal jets occurring in the inside collide if the experimental conditions are suitable. The interfaces of such parallel seam welded-aluminum sheets are observed by an optical microscope. Two inside weld zones are connected to each other with a small cavity.