Corrosion-fatigue interactions of high-temperature nickel alloys

Corrosion and fatigue aspects of high temperature turbine components made from Alloy 720Li and RR1000 have been studied with a view to understanding the potential failure mechanisms occurring in these materials. Understanding of such failure mechanisms is important in order to make safety improvements and significant cost savings by reducing engine downtime. Some exservice discs currently exhibit pit-like features at a specific location on the firtree lobes, which potentially may lead to more serious alloy fissuring. Shot peening is currently employed to improve fatigue resistance at the surface of components. This work aims to fully characterise these pits and fissure features in addition to shot peening, and the components in general, using advanced analytical techniques, in order that the failure mechanism(s) can be determined and mitigated against. [Continues.]