A Corrosion Resistant Alloy for Vacuum Brazed Aluminum Heat Exchangers

Vacuum brazed aluminum automobile radiators have exhibited a susceptibility to intergranular corrosion on the external tube surfaces, induced by road salt splash high in chlorides. A novel brazing sheet material with greatly improved perforation resistance has been developed to address this problem. Relative external corrosion resistance of conventional and experimental alloy systems was determined by accelerated corrosion testing of brazed composites and radiator sections in SWAAT. The new material, designated K319, exhibits an order of magnitude improvement in time to perforation in this test. A subsurface layer, anodic to the core alloy, is developed during the brazing process and accounts for the material's greatly enhanced resistance to perforation.