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SMALL CRACK GROWTH IN THE ALUMINIUM–LITHIUM ALLOYS 8090 AND 8091
Author(s) -
Nicholls D. J.,
Martin J. W.
Publication year - 1990
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.1460-2695.1990.tb00578.x
Subject(s) - materials science , aluminium , crack closure , metallurgy , slip (aerodynamics) , microstructure , alloy , aluminium alloy , paris' law , fracture mechanics , composite material , physics , thermodynamics
The relationship between microstructure and the fatigue behaviour of small cracks has been examined for the aluminium–lithium alloys 8090 and 8091 after peak ageing at 170°C. Duplex ageing and pre‐stretching were used to vary the distribution of S'precipitates and thus the distribution of slip. No effect of S'distribution an small crack growth was observed in either alloy. This is thought to be due to a combination of the lack of closure and lower overall slip reversibility in small cracks. Small cracks in 8091 were found to grow slower than in 8090 due to differences in grain shape rather than texture. Small cracks in both alloys were observed to grow much faster than long cracks for equivalent Δ K s. This difference was reduced when small crack data were compared with long crack data generated at R = 0.7 due to the reduced closure. The use of Δ J made long and small crack growth rates still more comparable.