Chromium Containing Amorphous Brazing Foils and Their Resistance to Automotive Exhaust Gas Condensate

Brazed stainless steel components for exhaust gas applications are well established and widespread used in the EU, US and JP vehicle industry in order to reduce emission levels. The launch of the cooled exhaust gas recirculation (EGR) technology in countries of South America and Asia having poor fuel qualities requires materials with an enhanced corrosion resistance. Especially the higher content of Sulphur and Chlorides within this low quality fuels leads to an increased risk of failure due to corrosive damage if the base- and brazing materials are not adapted. Quite recently the German Association of the Automotive Industry (VDA) set a new standard and testing procedure for corrosion testing of metallic materials exposed to exhaust condensate with different aggressive medias. The paper analyzes the corrosion behavior of brazed samples joined with different Ni-Cr and Fe-Ni-Cr base amorphous brazing foils as well as the recently developed Ni-Cr-Si-P foils. Different testing methods and medias including the new VDA testing standard were used for evaluation of the corrosion resistance.