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CRACK INITIATION MECHANISMS IN TORSIONAL FATIGUE
Author(s) -
Doquet V.
Publication year - 1997
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.1460-2695.1997.tb00280.x
Subject(s) - materials science , intergranular corrosion , torsion (gastropod) , lüders band , grain boundary , fatigue testing , ultimate tensile strength , composite material , scanning electron microscope , fatigue limit , crack closure , stress concentration , structural engineering , fracture mechanics , corrosion , microstructure , engineering , anatomy , medicine
— The development of fatigue damage in Co45Ni specimens during push—pull and reversed torsion tests, performed inside a scanning electron microscope, was observed and the different stress states compared. It appeared that transgranular crack initiation and development is delayed and intergranular crack initiation promoted under torsional loading. This was explained in terms of reduced surface distortion at the emergence of persistent slip bands (PSBs) and smaller compatibility stresses at the PSB‐matrix interfaces. The influence of the mechanical strength of grain boundaries on the difference between tensile and torsional fatigue lives is discussed.