High Temperature Corrosion Behavior of an Al-Doped Fe-Ni-Cr-Mo Alloy in Oxidizing Chlorine-Containing Atmosphere

The influence of aluminum (Al) doping content on the high-temperature chlorine corrosion behavior of 254SMO alloy was investigated in a simulated waste incinerator environment containing N2-2.6 vol.% CO2-1.3 vol.% O2-2700 vppm HCl at 700 ℃. The results demonstrate that as the Al content increases, the microstructure from a single-phase austenite to an intermetallic compound phase structure comprising (Fe,Ni) and FeAlCr, accompanied by grain refinement. The corrosion kinetics curves of 254SMO alloys with 0, 5, 10, and 15 at.% Al doping after 80 hours of corrosion all follow parabolic law. The 254SMO:5Al alloy exhibited the highest corrosion weight gain of 1.3280 mg·cm-2, while the 254SMO:15Al alloy showed the lowest weight gain of 0.1116 mg·cm-2. The chlorine corrosion product layer exhibits a tri-layer structure of "FexOy/Cr2O3/Al2O3", where the density of the inner Al2O3 layer increases with higher Al content, effectively inhibiting the chlorine cycle during the "active oxidation" process. The 254SMO:5Al alloy demonstrated poor corrosion resistance due to the discontinuous Al2O3 layer, leading to localized oxide formation. In contrast, The 254SMO:15Al alloy forms a continuous Cr2O3/Al2O3 composite oxide layer, significantly enhancing the inhibition efficiency against Cl- diffusion and achieving optimal high-temperature chlorine corrosion resistance