Corrosion behaviour of alumina-forming heat resistant alloy with Ti in high temperature steam

Abstract

The corrosion behaviour of an alumina-forming heat resistant alloy with high Ti (Fe-35Ni-16Cr-4.5Al-3Ti, wt%) was evaluated in high temperature steam. The alloy developed interfacial α-Al2O3 layer during the pre-oxidation treatment in air at 750 °C. However, it formed external Cr2O3 and internal γ-Al2O3 oxides on the austenite matrix during the steam corrosion at 750 °C for 1000 h. This behaviour is attributed to the increased oxygen permeability into the austenite matrix from the synergistic effect of steam and Ti. Meanwhile, the pre-oxidized alloy with interfacial α-Al2O3 layer showed improved corrosion protection with reduced weight gain in steam environment.