Fillers and fluxes for manual torch brazing

摘要

For manual torch brazing applications, welding distributors typically handle four families of filler metal alloys and three types of flux. The filler alloys come as bare metal, or flux-coated metal, in both rod and wire. Fluxes are either a white or black paste, or white powder. Robert Henson, technical director, AWS CWI, J.W. Harris Co. Inc., Mason, Ohio, says manual torch brazing is a common application performed both by individuals and manufacturers, for repair of items such as cracked cast iron pumps or leaking air-conditioning assemblies. According to Rod Rodriquez, All-State sales manager, Esab Welding Products, Florence, S.C., the process is suited for joining thin sheets of metal to thick plate stock or metals of widely different melting temperatures. It's used in applications where joints are irregular, both for single-assembly and short-run production. During the brazing process, molten filler metal cools and solidifies to create a metallurgical bond between workpiece materials. By definition, these fillers melt above 840 F deg. However, unlike welding, workpieces don't have to melt for fusion to occur. Thus, heating temperatures employed are below the melting point of the metals to be joined.