Accession Number : ADA138737

Title :   Preliminary Study of Thermomechanical Fatigue of Polycrystalline MAR-M 200.

Descriptive Note : Technical paper,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION CLEVELAND OH LEWIS RESEARCH CENTER

Personal Author(s) : Bill,R C ; Verrilli,M J ; McGraw,M A ; Halford,G R

PDF Url : ADA138737

Report Date : Feb 1984

Pagination or Media Count : 17

Abstract : Thermomechanical fatigue (TMF) experiments were conducted on polycrystalline MAR-M 200 over a cyclic temperature range of 500 to 1000 C. Inelastic strain ranges of 0.03 to 0.2 percent were imposed on the specimens. TMF lives were found to be significantly shorter than isothermal low-cycle-fatigue (LCF) life at the maximum cycle temperature, and in-phase cycling was more damaging than out-of-phase cycling. Extensive crack tip oxidation appeared to play a role in promoting the severity of in-phase cycling. Carbide particle - matrix interface cracking was also observed after in-phase TMF cycling. The applicability of various life prediction models to the TMF results obtained was assessed. It was concluded that current life prediction models based on isothermal data as input must be modified to be applicable to the TMF results. (Author)

Descriptors :   *Superalloys, Polycrystalline, Thermal fatigue, Thermomechanics, Mathematical prediction, Life expectancy(Service life), Cracking(Fracturing), Crack propagation, Isotherms, Strain(Mechanics), Tensile stress, Compressive properties, Thermocouples, Interfaces, Elastic properties, Poisson ratio, Microstructure, Oxidation, Carbides, Fatigue life, Test methods

Subject Categories : Properties of Metals and Alloys
      Crystallography
      Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE