Irreversibility of strain during low-cycle fatigue experiments of a precipitation-hardened alloy

Abstract In this precipitation-hardened alloy, containing δ′ (Al3Li) coherent particles, under conditions of peak-aged heat treatment and high applied plastic strain amplitude, the slip mode is mainly inhomogeneous and planar. It is shown that dwell time periods at ambient temperature superimposed on the basic cycling test induces, on reloading, a significant transient hardening. The mean cumulative irreversible shear strain within the bands may be evaluated from a simple geometrical model. This model is based on the variation in the mean sheared section of δ′ particles and takes into account the transient hardening measurements. From these results and the quantity of slip bands estimated from transmission electron microscopy observations it has been found that the shearing is relatively irreversible during the first cycles and becomes more and more reversible once a stable deformation substructure is formed. The volume fraction of softest bands, where the particles are entirely sheared, and their mean cu...

[1]  M. Clavel,et al.  Evidence of S′ phase shearing in an aluminium-lithium alloy , 1988 .

[2]  D. Dowson.  Interface dynamics : proceedings of the 14th Leeds-Lyon Symposium on Tribology held at the Institut national des sciences appliquées, Lyon, France, 8th-11th September 1987 , 1988 .

[3]  D. Evelyne.  Thèse de doctorat d'Etat , 1988 .

[4]  Y. Bréchet,et al.  Experimental (TEM and STEM) investigation and theoretical approach to the fatigue-induced dissolution of δ' precipitates in a 2.5 wt% Al−Li alloy , 1987 .

[5]  J. Wert,et al.  Correlation between S′ precipitation and the Portevin-le Chatelier effect in an AlLiCuMgZr alloy , 1985 .

[6]  A. Pineau,et al.  Dislocation-precipitate interaction and cyclic stress-strain behavior of a γ′ strengthened superalloy , 1978 .

[7]  M. James,et al.  Reversible strain in cyclic plastic deformation , 1978 .

[8]  E. Hornbogen,et al.  The effect of inhomogeneity of cyclic strain on initiation of cracks , 1978 .

[9]  G. Baudry,et al.  Estimating the reversibility of plastic strain during fatigue with the martensitic transformation , 1977 .

[10]  D. Kuhlmann-wilsdorf,et al.  Dislocation behavior in fatigue , 1977 .

[11]  C. Laird,et al.  Strain localization in cyclic deformation of copper single crystals , 1975 .

[12]  C. Laird,et al.  Cyclic stress—strain response of two-phase alloys Part I. Microstructures containing particles penetrable by dislocations , 1974 .

[13]  A. Abel,et al.  The Bauschinger effect and discontinuous yielding , 1972 .

[14]  R. C. Daniel,et al.  The Bauschinger effect and cyclic hardening in copper , 1971 .