Microstructure Characterization and Creep Behavior on the Casting CMM88Y Super Alloy turbine Blade

In this study, the mechanical properties of gas turbine blades are investigated by investment casting method. These Nickel-based alloys blades, with standard name, CM88Y, are made in Ukraine. Currently, these blades are used in Zorya brand gas turbines in most power plants in Iran. Therefore the technical information about this alloy are very limited. In this investigation, the CM88Y Nickel base alloy as a Ni-Co heat resistant super-alloy was assessed by a lot of destructive tests. Mechanical and creep properties as well as the phase microstructure for a turbine blade were measured after 6000 and 18,000 hours. The creep results by adding Larson-Miller parameter, revealed that the 18,000-hour blade with the hot-spot zone defect has a creep life less than 3,800 hours due to the TBC erosion and hot-spot defect. Also, the gamma prime phase has changed from a cubic morphology to a spherical shape associated to the coarsening phenomenon.