Fatigue life prediction model for nickel-based single crystal and directionally solidified superalloy

A lifing model was developed to predict the high temperature,low-cycle fatigue-creep(HTLCF-C) life behavior of nickel-based single crystal(SC) and directionally solidified(DS) superalloy.By modifying total strain range with a crystal orientation-dependent function,the mean and maximum stress and its range during a fatigue cycle,as well as dwell time at peak stress or strain level were incorporated into the lifing model using the idea of cyclic damage accumulation(CDA).The model was validated by correlating the fatigue data of DZ125,DD3 and DD6 superalloy under different temperatures,crystal orientations and holding times.Good agreements between predicted and experimental lives were yielded in these two factors for both DS and SC superalloy.The results show that the approach has better adaptability to model the anisotropic and HTLCF-C life behavior of turbine blade materials.