Corrosion Behavior of HSLA-100 Steel in Molten Cryolite After Surface Oxidation

Development of inert anodes in the Hall – Heroult for aluminum production has been one of the major challenges in recent years. In the present study, the use of HSLA-100 steel has been studied for use as an inert metal anode in aluminum production industry. Hence, in order to create a corrosion resistant surface oxide layer, the alloy got surface heat treatment. After surface heat treatment at 1000ºC for periods of 1, 5 and 10 hours on the alloy, the behavior of oxidized samples studied in molten cryolite at 930 ºC for 20 hours. EDS and XRD studies showed that after surface oxidation on the alloy mainly were formed iron phases as Fe2O3 with compounds containing of nickel, chromium, copper and aluminum in the oxide layer. So the oxidized sample for 1 hour that the thickness of oxide layer was about 237μm, has the highest corrosion resistance in corrosive cryolite – alumina environment. Finally, the mechanism of corrosion occurred in the corroded samples were studied in the mentioned environment.