镍基高温合金DZ125的单边缺口蠕变行为

In order to study the problem of creep persistence under complex stress conditions caused by the asymmetric structure characteristics, this paper performed creep tests on single-edge notched flat specimens of Ni-based superalloy DZ125, and revealed the weakening effect of the endurance performance under the action of the asymmetric structure characteristics. According to the analysis of the crack initiation mechanism of the notched specimens, it is found that the creep crack initiation at the root of the notch is due to both the stress concentration at the root of the notch and the structural defects between the dendrites. Based on the visco-plastic constitutive theory coupled with K-R creep damage law, the completely different stress distribution characteristics of the notch root section after loading and creep relaxation is revealed. Combined with the observed crack initiation and fracture morphology of specimens, the additional bending moment caused by the single-edge notched specimen aggravates the plastic deformation accumulation process area near the notch root. At the same time,the compressive stress area on the bisector of the notch can be better related to the instantaneous fracture characteristics of the fracture.