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Ratcheting behaviour and mean stress considerations in uniaxial low‐cycle fatigue of Inconel 718 at 649 °C
Author(s) -
PARK S. J.,
KIM K. S.,
KIM H. S.
Publication year - 2007
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.1460-2695.2007.01177.x
Subject(s) - inconel , amplitude , stress (linguistics) , materials science , structural engineering , mechanics , mathematics , composite material , engineering , physics , linguistics , philosophy , alloy , quantum mechanics
The ratcheting behaviour of Inconel 718 was investigated at 649 °C under uniaxial cyclic loading. Stress‐control tests have been conducted at various combinations of stress amplitude and mean stress. The ratcheting strain at failure increases with increasing mean stress for a given stress amplitude and with decreasing stress amplitude for a given mean stress. Fatigue lives were correlated using three mean stress models: the Goodman equation, the Smith–Watson–Topper (SWT) parameter and the Walker parameter. It has been shown that the Goodman equation and the SWT parameter do not correlate life data, while the Walker parameter yields acceptable correlation. The SWT parameter was modified to incorporate the ratcheting effect. The new parameter is found to yield correlation similar to that of the Walker parameter.