The nickel based superalloy 720Li is employed in the gas turbine due to its mechanical performance at elevated temperature. A comprehensive assessment of the materials behaviour under representative service conditions is reported to address the drive for ever increasing temperatures and more arduous environmental exposure. Fatigue experiments have been performed in an air and air/SOx environment at 700 ∘C containing a mixed salt as a contaminant. There is an intimate relationship between local salt level (flux), stress level and stress state, i.e. static or cyclic. The interaction with these variables with the work hardened layer present on the surface of all tested specimens as a result of the shot peening process directly affects the crack initiation process. If specific conditions of environment and stress are achieved, a significant reduction in fatigue life is observed.
Hollie Rosier1, Karen Perkins1, Andrew Girling1, Jonathan Leggett2 and Grant Gibson2
1 College of Engineering, Swansea University, Singleton Park, Swansea, SA2 8PP, UK
2 Rolls-Royce plc, PO Box 31, Derby, DE24 8BJ, UK
MATEC Web of Conferences: EUROSUPERALLOYS 2014 – 2nd European Symposium on Superalloys and their Applications 2014, Vol 14 (03001), doi: 10.1051/matecconf/20141403001