Arc welding of copper and steel materials with wires made of aluminium bronze is preferred when good high-temperature strength and high corrosion and scaling resistance of the joints are required. However, brazing alloys made of aluminium bronze cannot be used for furnace brazing because the high oxygen affinity of the aluminium causes significant oxidation of the brazing alloy already in the initial heating phase, which then prevents wetting of the joining surfaces. To circumvent this problem, composite brazing wires consisting of a copper sheath and an aluminium core were developed, which only alloy to the desired aluminium bronze during the actual brazing process. The temperature control during brazing can have a considerable influence on the brazing metallurgy and hence on the technical properties of the resulting brazed joint. The aim of the project, extracts of which are reported here, was to investigate these dependencies and to develop suitable aluminium bronze composite brazing alloys and brazing processes.
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