Effect of Microstructure on Thermo-Mechanical and Isothermal Low Cycle Fatigue Failures of a Single Crystal Ni-Base Superalloy

Abstract:

Behavior of thermo-mechanical fatigue (TMF) failure of a single crystal Ni-base superalloy, CMSX-4, was studied and, compared with isothermal low-cycle fatigue (ILCF) of it. Strain-controlled TMF and ILCF tests of CMSX-4 were carried out under various test conditions, where the experimental variables were strain rates, strain ratio, test temperature and the range, and strain/temperature phase angle. At first it was shown from the experiments that the TMF and LCF failures associated with some noteworthy characteristics were rarely seen in the traditional pollycrystalline heat-resistant alloys. These phenomena could be explained inadequately, on the basis of the macroscopic parameters and the historical failure criteria; e.g., Manson-Coffin law and Ostergren approach. A new micromechanics model is proposed to predict the TMF and LCF lives, based on the Eshelby's theory.

• Periodical: Key Engineering Materials (Volumes 353-358)
• Pages: 491-494
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.353-358.491
• Online since: September 2007
• Authors: Motoki Sakaguchi, Masakazu Okazaki
• Keywords: Low Cycle Fatigue, Microstructure, Single Crystal Nickel-Base Superalloy, Thermo-Mechanical Fatigue (TMF)

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