The Effects of Phase Angle on Thermomechanical Fatigue Behavior and Life in DS Superalloy DZ125

Three types of test (in-phase,out-of-phase and-135 ° phase angle) were performed in directional solidification superalloy DZ125,with temperature cycling from 550'C to 1000 C. The results of experiment showed that DS superalloy DZ125 exhibited a crossover point of the in-phase and out-of-phase mechanical strain-life curves, - 135° phase angle lives were longer than that of in-phase and out-of-phase thermomechanical fatigue. Besides fatigue damage, creep damage and oxidation damage exist in thermal-mechanical fatigue. The effect of phase angle on TMF cyclic stress-strain response in DS superalloy DZ125 was investigated. Manson-Coffin e-quation, Ostergren method and microcrack propagation model were chosen to predict TMF life. The results of TMF life prediction showed that all of methods chosen were able to give a reasonable life prediction for DS superalloy DZ125.