Strip welding of aluminum bronze

Abstract

Aluminum bronze has mechanical properties comparable to medium carbon steels and possesses excellent resistance to corrosion and is extremely pleasing in appearance. With these attributes, it is fast replacing steel in several critical machine components without significant change in design. The discouraging aspects are its high cost and difficulty in casting and fabrication. The purpose of this study was to evolve strip welding technology to overlay aluminum bronze strip over a base metal which could be either aluminum bronze itself or steel using submerged are welding technique. This makes the process of fabrication and salvaging quicker, and with the life of the component thus enhanced, makes it economical to use. Initially, a few welds were made using 30 mm x 0.5 mm and 60 mm x 0.5 mm strips of aluminum bronze as electrode and 8 '' x 4 '' x 1 '' aluminum bronze plates or steel plates of the same size as base metal. A cryolite-alumina base flux developed at the University of Wisconsin-Milwaukee which worked very well when the electrode used was in the form of wire, was used to submerge the are. The welds made with DCEN or DCEP were full of defects - the most pertinent being profuse presence of flux at the interface of the base metal and the weld metal. The phenomena was fully analysed making use of (1) the surface properties of base metal, flux, and the weld metal, (2) electrostatics of the system, and (3) the electrochemistry of the flux ingredients. Based on this analysis, suitable fluxes were developed and the welding technology was evolved to deposit multipass welds of aluminum bronze over aluminum bronze or steel using strip electrode. These welds were free from defects and conformed to the theoretical stipulations.