Investigations of the corrosion damage process of the brazed joint AISI 304L/BNi-2

[Display omitted] •Determination of miscellaneous corrosive mechanism, their formation and progression.•Change of mechanical properties due to corrosive attack.•Fractographic examination. One of the most frequently used material combinations to produce heat exchangers for automotive exhaust systems are vacuum brazed AISI 304L/BNi-2 components. In order to simulate the influence of condensate corrosion on such parts during service, the well-established test procedure for testing the resistance of metallic materials to condensate corrosion in exhaust gas, VDA 230-214, is used in this study. For a test duration of up to 6 weeks, miscellaneous corrosive mechanisms were observed and examined concerning their formation and progression. The corrosive attack starts at the diffusion zone on the base metal side due to the formation of chromium borides and the reduced nickel content. Between week 4 and 5, the greatest material removal was observed, which goes in line with a diameter reduction from 6.5 mm down to 5.8 mm of the load-bearing area. In this regard, the ultimate tensile strength drops down from 253.3 MPa to 147.8 MPa after 6 weeks of corrosive testing.