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Fatigue behaviour and life predictions of case‐hardened steels
Author(s) -
YIN F.,
FATEMI A.
Publication year - 2009
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.1460-2695.2009.01326.x
Subject(s) - materials science , fractography , nucleation , fatigue limit , hardened steel , residual stress , fracture (geology) , fracture mechanics , cracking , relaxation (psychology) , crack closure , composite material , structural engineering , metallurgy , engineering , thermodynamics , psychology , social psychology , physics
This paper presents experimental and analytical results on fatigue behaviour of case‐hardened steel. Fully reversed strain‐controlled constant amplitude axial fatigue tests were performed on through‐hardened case, through‐hardened core and case‐hardened steel specimens. Surface versus sub‐surface cracking and the role of residual stresses and their relaxation are discussed. Multi‐layer models of the case‐hardened specimens were used to predict crack nucleation sites as well as fatigue lives, and the predictions corresponded well with the experimental results. Linear elastic fracture mechanics (LEFM) was also used to conduct fatigue crack growth analysis to further explain the experimental observations from the fracture surfaces of the case‐hardened specimens. A fatigue strength estimation method based on hardness and inclusion size was used to estimate the fatigue limit of the materials investigated. Fractography of fracture surfaces and crack nucleation location are also presented.