Method for improving corrosion resistance of plate-type vacuum brazed evaporators

摘要

A method is provided for enhancing the corrosion resistance of a 3000 series aluminum alloy. In particular, the method encompasses processing steps which promote corrosion resistance of brazed assemblies, such as tubeplate-and-center type evaporator units for automobile air conditioning systems. The method is directed at virtually eliminating the precipitation of CuAl2 particles in the grain boundaries of a 3000 series aluminum alloy, such that evaporator units formed from such an alloy are characterized by enhanced and more consistent corrosion resistance, as well as improved mechanical properties. The primary processing step involves rapidly cooling the evaporator unit after brazing so as to maintain the copper present in the 3000 series aluminum alloy in solid solution. In addition, the reheat and annealing steps are preferably controlled so as to avoid the formation of CuAl2 particles prior to brazing.