SEDL / STP / STP1186-EB / STP24246S

Fatigue Life Prediction Under Thermal-Mechanical Loading in a Nickel-Base Superalloy

Rémy, L
Centre des Materiaux P. M. Fourt, Ecole des Mines de Paris, URA CNRS, Evry,

Bernard, H
Peugot S.A., Velizy,

Malpertu, JL
Joseph Paris S.A., Nantes,

Rezai-Aria, F
Ecole Polytechnique Federale de Lausanne, Ecublens,

Pages: 14    Published: Jan 1993

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Abstract

Thermal-mechanical fatigue of IN-100, a cast nickel base superalloy, was previously shown to involve mainly early crack growth using either bare or aluminized specimens. This crack growth was found to be controlled by interdendritic oxidation. A model for engineering life to crack initiation is thus proposed to describe this microcrack growth phase using local stresses in a microstructural volume element at the crack tip. The identification of damage equations involves fatigue crack growth data on compact tension (CT) specimens, interdendritic oxidation kinetics measurements and fatigue crack growth on CT specimens that have been embrittled by previous oxidation at high temperature. The application of this model to life prediction is shown for low cycle fatigue and thermal-mechanical fatigue specimens of bare and coated specimens as well as for thermal shock experiments.