Fatigue & Fracture of Engineering Materials & Structures · 1994 · 38 citations · 10 references
EngineeringMaterials EngineeringMaterials ScienceMechanical Behavior Of MaterialsMetallic MaterialsMetallurgyAlloysFailure TheoriesFatigueFracture MechanicsNickel-based SuperalloysPowder MetallurgyCrack InitiationCrack Initiation ModelingCracksFailure MechanismsFatigue Crack InitiationFatigue TestingPowder Metallurgy SuperalloysSize Effect Modeling
Abstract— Low cycle fatigue (LCF) testing of powder metallurgy (PM) superalloys has determined that LCF cracks initiate from defects such as pores and ceramic inclusions located either at the surface or internally. The ratio of surface‐to‐internal crack initiation sites depends upon experimental conditions. In the current work, a probabilistic model is presented that describes the competition between these two failure mechanisms from a single experimental parameter, μ. The model predicts the size distribution of defects which initiate LCF cracks, as well as the proportion of specimens which fail as a result of internally located defects. Model predictions were found to correlate well with experimental LCF data obtained from a N18 PM Ni‐base superalloy. The model further enables evaluation of a “size effect”, as it predicts that internal crack initiation is favoured for larger components/specimens.
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