Steam Oxidation Behavior of Advanced Steels and Ni-Based Alloys at 800 A°C

This publication studies the steam oxidation behavior of advanced steels (309S, 310S and HR3C) and Ni-based alloys (Haynes(A (R)) 230(A (R)), alloy 263, alloy 617 and Haynes(A (R)) 282(A (R))) exposed at 800 A degrees C for 2000 h under 1 bar pressure, in a pure water steam system. The results revealed that all exposed materials showed relatively low weight gain, with no spallation of the oxide scale within the 2000 h of exposure. XRD analysis showed that Ni-based alloys developed an oxide scale consisting of four main phases: Cr2O3 (alloy 617, Haynes(A (R)) 282(A (R)), alloy 263 and Haynes(A (R)) 230(A (R))), MnCr2O4 (alloy 617, Haynes(A (R)) 282(A (R)) and Haynes(A (R)) 230(A (R))), NiCr2O4 (alloy 617) and TiO2 (alloy 263, Haynes(A (R)) 282(A (R))). In contrast, advanced steels showed the development of Cr2O3, MnCr2O4, Mn7SiO12, FeMn(SiO4) and SiO2 phases. The steel with the highest Cr content showed the formation of Fe3O4 and the thickest oxide scale.