When using AA3000 series and AA1000 series aluminum alloys to produce extruded
products for heat exchanger applications, by controlling the level of copper and
nickel in the alloy to very low levels it is possible to produce excellent corrosion
resistance both before and after a brazing cycle. To achieve these results, the
copper content should be no more than 0.006% by weight and the nickel no more than
0.005% by weight. A typical alloy of the invention contains about 0.001-0.5% by
weight manganese, 0.001-0.7% by weight iron, 0.001-0.02% by weight titanium, 0.001-0.3%
by weight silicon, less than 0.006% by weight copper, less than 0.005% by weight
nickel and 0.001-0.02% by weight zinc, with the balance consisting of aluminum
and incidental impurities. No zinc addition to the alloy is required either by
zinc spraying or by alloy addition.