Premium
EFFECTS OF AIR AND INERT ENVIRONMENTS ON THE NEAR THRESHOLD FATIGUE CRACK GROWTH BEHAVIOR OF ALLOY 718
Author(s) -
Yuen J. L.,
Schmidt C. G.,
Roy P.
Publication year - 1985
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.1460-2695.1985.tb00420.x
Subject(s) - materials science , alloy , oxide , paris' law , crack closure , helium , displacement (psychology) , fracture (geology) , composite material , inert gas , metallurgy , fracture mechanics , chemistry , organic chemistry , psychology , psychotherapist
The near threshold fatigue crack growth behavior of alloy 718 was studied in air and helium environments at room temperature and at 538°C. Tests were performed at 100 Hz and at load ratios of 0.1 and 0.5. At room temperature and at 538°C, the Δ K th values in helium were lower than in air. The Δ K th values in air decreased with increasing load ratio. These results can be explained with a model that involves the accumulation of oxide in the crack which enhances crack closure. In the air tests, the oxide build‐up on the fatigue fracture surfaces at Δ K th was of the order of magnitude as the crack tip opening displacement. In the helium tests, no significant build‐up of oxide on the fracture surface at threshold was found.