Lj. Chen et al., An assessment of three creep-fatigue life prediction methods for nickel-based superalloy GH4049, FATIG FRACT, 23(6), 2000, pp. 509-519
Citations number
24
Categorie Soggetti
Material Science & Engineering
Journal title
FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES
High-temperature low-cycle fatigue tests with and without a 10-s strain hol
d period in a cycle were performed on a nickel base superalloy GH4049 under
a fully reversed axial total strain control mode. Three creep-fatigue life
prediction methods are chosen to analyse the experimental data. These meth
ods are the linear damage summation method (LDS), the strain range partitio
ning method (SRP) and the strain energy partitioning method (SEP). Their ab
ility to predict creep-fatigue lives of GH4049 at 700, 800 and 850 degrees
C has been evaluated. It is found that the SEP method shows an advantage ov
er the SRP method for all the tests under consideration. At 850 degrees C,
the LDS and SEP methods give a more satisfactory prediction for creep-fatig
ue lives. At the temperatures of 700 and 800 degrees C, the SRP and SEP met
hods can correlate the life data better than the LDS method. In addition, t
he differences in predictive ability of these methods have also been analys
ed. The scanning electron microscopy (SEM) examination of fracture surfaces
reveals that under creep-fatigue test conditions crack initiation mode is
transgranular, while crack propagation mode is either intergranular plus tr
ansgranular or entirely intergranular, dependent on test temperature.