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Effect of solidification cooling rate on the fatigue life of A356.2‐T6 cast aluminium alloy
Author(s) -
Bo Zhang,
Guihai Chen,
Poirier
Publication year - 2000
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 - 10.1046/j.1460-2695.2000.00299.x
Subject(s) - aluminium , metallurgy , alloy , materials science , aluminium alloy
The effect of the cooling rate during solidification on the fatigue life of a cast aluminium alloy (A356.2‐T6) is examined. The fatigue lives were determined for specimens removed from ingots with a gradient in cooling rates along their heights. Low‐ and high‐cycle fatigue tests were conducted under both axial loading and reciprocating‐bending conditions at a stress (strain) ratio ( R ) of −1.0, 0.1 and 0.2. Results show that the fatigue life decreases by a factor of three in low‐cycle fatigue ( R = −1.0) and by a factor of 100 in high‐cycle fatigue ( R = 0.1) as solidification cooling rate decreases from ~10 to ~0.3 K s −1 , as indicated by measurements of the secondary dendrite arm spacings in the ingots. Fatigue cracks initiated from porosity in the material solidified at slower cooling rates. When pore size is below a critical size of ~80 μm, as a result of increasing the cooling rate, the fatigue cracks initiated from near‐surface eutectic‐microconstituent. When present at or near the surface, large oxide inclusions initiated fatigue cracks.