Process for improving the corrosion resistance of brazing sheet

Abstract From the Canadian patent

A process is described for producing a corrosion resistant aluminum composite sheet product for use in brazing. The process steps comprise:, (a) casting an aluminum-base core material containing no more than 0.4% iron, no more than 0.15% silicon from about, 0.1% to about 0.6% copper and from about 0.7% to about 1.5 manganese, (b) cladding the as-cast core material with an aluminumbase brazing alloy, with hot rolling to form a sheet product and, (c) directly cold rolling the sheet product to final gauge. When this product is subjected to a brazing heat cycle, a band of dense precipitate is formed in the core alloy immediately adjacent the cladding which protects the core against corrosion.