Thermo-mechanical fatigue characteristics of CMSX-4 applied to the high-pressure turbine first-stage single-crystal rotor blade

To increase efficiency and reduce greenhouse gas emissions, the operating temperatures of combined power plants have increased. As a result, high-pressure turbine (HPT) blades are subjected to increasingly harsh operating conditions, which cause thermo-mechanical fatigue (TMF) damage and reduce the lifetimes of the gas turbine blades. Therefore, accurate analysis of the TMF characteristics caused by various strain and temperature conditions is needed to ensure the integrity and provide accurate lifetime assessments of the components of gas turbines. However, there have been few studies on the TMF characteristics of single crystal Ni-based superalloys, particularly CMSX-4. In this study, the TMF characteristics of a oriented single crystal Ni-based superalloy CMSX-4, which is used for HPT first-stage rotor blades, were investigated via strain-controlled TMF tests and the fatigue fractogra-phy was observed using scanning electron microscopy. Additionally, the relationship between the fatigue lifetimes of CMSX-4 and IN738LC was evaluated, and the tensile properties and microstructures at different temperature were investigated. Such TMF test results can be useful for analyzing the thermo-mechanical behavior and predicting the lifetimes of blades.