Combined cycle fatigue of gas turbine blade materials at elevated temperature

In gas turbine engines for aerospace propulsion, and in particular in the HP and LP stage blading where the highest temperatures are experienced, the assessment of the fatigue damage mechanisms due to the interaction of high cycle fatigue (due to vibration phenomena) and low cycle fatigue (due to ground-air-ground major engine cycling) are of paramount importance for the structural integrity of the components. In order to experimentally evaluate the material performance in this highly demanding environment, a number of combined cycle fatigue (CCF) and low cycle fatigue (LCF) tests with and without dwell have been carried out on an investment cast polycrys- talline nickel superalloy, at temperatures up to 870 °C, on specimens with pre-cracked coating. Comparison of the CCF and the LCF tests with dwell with conventional LCF tests is presented herein.