Electrical Resistance of Aluminum to Steel ETJs vs Time and Temperature


Electrical transition joints (ETJ) are used for welding aluminum to steel in reduction cells. ETJs can experience temperatures up to 600°C which can cause strength loss and resistance increase. This results from formation of brittle, high resistance Fe-Al intermetallics at the bond. Over the time required for mechanical failure to occur, the resistance can increase dramatically. The increase can be altered by inserting a titanium or chromium interlayer. Compared to BiClad, the temperature at which resistance begins to increase is raised significantly with a titanium interlayer. As-manufactured, resistance of a standard BiClad specimen is 40.0 m-ohm, chromium interlayer ETJ is 55.8, and titanium interlayer ETJ is 44.4. After 188 hours at 500°C, the bi-clad had fallen apart, the chrome interlayer ETJ resistance had increased to 11,250 and the titanium interlayer ETJ exhibited no change.


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