During the test, no spallation of the external oxide scale was observed. The kinetic data showed that only the 263 alloy oxidized according to parabolic behaviour, whereas the other alloys deviated from the parabolic rate law, with time exponents of 0.4-0.6 or 0.3. Finally, cross-sectioned investigations of the exposed samples revealed that Ni-based alloys underwent extended internal oxidation, with the highest extent in HAYNES Ò 282 Ò reaching 25 lm and the lowest in HAYNES

No abstract

No abstract

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 Ò 230 Ò , 617 alloy, two gamma-prime (c 0 ) strengthened alloys; 263 and Haynes Ò 282 Ò 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 MnCr 2 O 4 spinels and Cr 2 O 3 , with the exception of 617 alloy where NiCr 2 O 4 spinels and Cr 2 O 3 were found. In Fe-based alloys, Cr 2 O 3 , MnCr 2 O 4 spinels, Fe,Mn(SiO) 4 , and finally Fe 3 O 4 developed. No evaporation of chromia has been found within 1000 h test period. Furthermore, the development of TiO 2 was not observed into a large extent in Haynes Ò 282 Ò and 263 alloy, in contrast to the study performed at 800°C under the same steam environment conditions.

No abstract