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SOME OBSERVATIONS ON SMALL FATIGUE CRACKS IN A SUPERALLOY
Author(s) -
SHELDON G. P.,
COOK T. S.,
JONES J. W.,
LANKFORD J.
Publication year - 1980
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.1980.tb01361.x
Subject(s) - superalloy , materials science , stress intensity factor , deformation (meteorology) , fracture (geology) , fracture mechanics , microstructure , metallurgy , stress field , composite material , crack closure , stress (linguistics) , powder metallurgy , structural engineering , finite element method , engineering , linguistics , philosophy
—An investigation into the applicability of linear elastic fracture mechanics to very small fatigue cracks growing in a powder metallurgy nickel base superalloy is described. An unusual specimen was designed to facilitate the study of these small cracks. The stress intensity factor for the specimen was estimated and then calculated from the plastic zone size as determined by interferometry. The crack tip deformation field was also observed in the SEM and by stereoscopic viewing. These observations showed that the macroscopic deformation field was the same for both the long and short cracks, and was controlled by the stress intensity. The fatigue crack tip was found to interact strongly with the material microstructure and the localgrowth rate cannot be correlated with fracture mechanics quantities.