Low-cycle fatigue of MCrAlY-coated superalloys: a fracture mechanics-based analysis

A fracture mechanics-based method was proposed to quantify the low-cycle fatigue (LCF) life reduction of superalloys deposited with MCrAlY coating. A series of LCF tests were conducted under different temperatures to verify the accuracy of the model. The effect of the coating shows temperature-related behaviour. At 980°C, the coating reduced the LCF life of the samples. Furthermore, the coating-induced fatigue life reduction increased with the stress amplitude. However, at 850°C, the coating was beneficial to the fatigue life at low-stress amplitudes but harmful at high stress amplitudes. Based on the aforementioned data, a life-prediction model of the coated superalloy was proposed that agreed well with the test results.