Abstract
Nickel-based creep resisting alloys (strengthened by γ´) are the basic materials for high-temperature constructional parts in aircraft engines and energy units. These parts are exposed to combined effects of mechanical stresses, high temperature and dioxide-corrosion conditions. The microstructure changes of cast polycrystalline Ni-based superalloy IN713LC after creep exposure were studied. Three specimens with three different diameters were used for creep tests. The degradation stage (damage parameter π) was determined for all parts of specimens. Individual parts of specimens were metallographic observed and analyzed by image analysis after rupture. The results were compared with model of stress distribution in the specimen with potential damage in the centre of the specimen.
Highlights
Ni-based superalloys containing hardening ordered γphase have unique high-temperature properties
Stress and time conditions, the creep or an interaction of creep and fatigue may reduce the capability of structures; the directional coarsening of the γ/ γmicrostructure may occur, leading to the formation called rafting [2,3,4,5]
Values of damage parameter π(t) (Eq 1) in a normalized form were obtained from this testing program [7] in according to [8]
Summary
Ni-based superalloys containing hardening ordered γphase have unique high-temperature properties. The mesh of the finite elements was nonhomogenously distributed due to stress concentrations in the area where is change of the specimen diameter. Important question is influence of the creep cracks on the stress distribution in the specimen.
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