Low cycle fatigue modeling for nickel-based single crystal superalloy

Abstract

The low cycle fatigue (LCF) characteristics of nickel-based single crystal (SC) superalloy have been experimentally and numerically investigated. The effects of crystallographic orientation, load ratio and stress concentration are studied. In order to model the effect of crystallographic orientation, a new orientation factor, which is relevant to the yield strength, is constructed. On the other hand, a new asymmetrical loading factor is introduced to describe the effect of load ratio. The LCF model for SC superalloy smooth specimen is established with these new damage parameters. The effect of the strain gradient on the LCF life of SC superalloy is further studied, which is applied to the evaluation of the LCF life of SC superalloy notched specimen. The LCF model proposed is validated by the experimental data of SC superalloy DD3 and PWA1480.

Keywords:

• Nickel-based single crystal superalloy
• low cycle fatigue
• crystallographic orientation
• load ratio
• stress concentration

Acknowledgements

This research is supported by the Jiangsu Province Key Laboratory of Aerospace Power System. The assistance of S.H. Yang in carrying out experiments is gratefully acknowledged. The authors are indebted to Dr. Guowei Zhou for the detailed discussion of this work.