The relationship of stress and temperature on high-temperature corrosion fracture mechanism of waspaloy in various catalyst environments

High temperature catalyst from the fluid catalytic cracking process can, under certain conditions, lead to oxidation attack of power recovery turbine materials. This oxidation attack can cause blade failures in the location of the blade/disk root attachment where the stress intensity at the oxide location exceeds the critical stress intensity necessary for fracture to occur. The relationship of stress intensity and temperature and how the catalyst environment effects the fracture toughness of the material are addressed. The influence of catalyst on the mechanical properties of waspaloy is illustrated from a series of stress rupture tests that were conducted for several different sets of ``environmental conditions''. The results show that, under certain conditions, the presence of catalyst can lead to rapid failure. An attempt was made to ascertain what species may have been responsible for the rapid failures. Preventative measures that have been developed by Elliott company are highlighted, such as a steam barrier system, protective coatings, and a new superalloy, RK1000.