LAUSR

The aim of the work was to investigate corrosion resistance of highly alloyed steels and Ni-based alloys in a steam atmosphere for 1000 h at 700 °C. In these steam oxidation experiments, two solid solution strengthened alloys; Haynes® 230®, 617 alloy, two gamma-prime (γ′) strengthened alloys; 263 and Haynes® 282® and three Cr+Ni- rich stainless steels: 309S, 310S and HR3C austenitic steels were exposed. The study showed that the materials exposed commonly developed thin oxide scales; in Ni-based alloys, these consisted of mainly MnCr2O4 spinels and Cr2O3, with the exception of 617 alloy where NiCr2O4 spinels and Cr2O3 were found. In Fe-based alloys, Cr2O3, MnCr2O4 spinels, Fe,Mn(SiO)4, and finally Fe3O4 developed. No evaporation of chromia has been found within 1000 h test period. Furthermore, the development of TiO2 was not observed into a large extent in Haynes® 282® and 263 alloy, in contrast to the study performed at 800 °C under the same steam environment conditions.