TEMPERATURE EFFECT ON LOW-CYCLE FATIGUE BEHAVIOR OF NICKEL-BASED SINGLE CRYSTALLINE SUPERALLOY
- Resource Type
- Academic Journal
- Authors
- Xianfeng Ma; Huiji Shi; Jialin Gu; Zhaoxi Wang; Harald Harders; Thomas Malow
- Source
- 固体力学学报(英文版) / ACTA MECHANICA SOLIDA SINICA. 21(4):289-297
- Subject
- low cycle fatigue
single crystal
nickel-based superalloy
- Language
- Chinese
- ISSN
- 0894-9166
The low-cycle fatigue (LCF) behavior of a nickel-based single crystal superalloy with [001] orientation was studied at an intermediate temperature of To℃ and a higher temper ature of To + 250℃ under a constant low strain rate of 10-3 s-1 in ambient atmosphere.The superalloy exhibited cyclic tension-compression asymmetry which is dependent on the temper ature and applied strain amplitude.Analysis on the fracture surfaces showed that the surface and subsurface casting mieropores were the major crack initiation sites.Interior Ta-rich carbides were frequently observed in all specimens.Two distinct types of fracture were suggested by frac togaphy.One type was characterized by Mode-Ⅰ cracking with a microscopically rough surface at To + 250℃.Whereas the other type at lower temperature To℃ favored either one or several of the octahedral {111} planes,in contrast to the normal Mode-Ⅰ growth mode typically observed at low loading frequencies (several Hz).The failure mechanisms for two cracking modes are shearing of γ' precipitates together with the matrix at To℃ and cracking confined in the matrix and the γ/γ'interface at To + 250℃.