Internal oxidation depth penetration in Ni based alloys at high temperatures
The aim of the paper was to investigate internal oxidation process under steam oxidation conditions and steam oxidation behaviour of two solid-solution strengthened alloys; UNS N06230, UNS N06617, two gamma - prime (i§â) strengthened UNS N07263 and UNS N07208. The samples have been tested under 1 bar pressure in 100% water â steam â water system in temperature range 700 - 800 oC for 3000 hours. The study has showed that Ni based solid-solution strengthened alloys; UNS N06230, UNS N06617 developed mainly Cr2O3 and MnCr2O4 phases on their surfaces, whereas gamma - prime (i§â) strengthened alloys; UNS N07263 and UNS N07208 presented the formation of Cr2O3, TiO2 and MnTiO3 phases respectively indicating slightly higher corrosion degradation rate. The oxidised Ni based alloys showed the formation of an internal oxidation process, with different depths. The observed difference in internal oxidation depth depends mainly on the concentration of Al and Ti in the metal matrix. In the alloys where Ti and A...