The present paper reviews experimental results about the effect of grain size on cyclic stress-strain behaviour of nickel material with high purity (99.99%). The effect of grain size on cyclic stress-strain behaviour can be described using the classical Hall-Petch relationship: Σ=Σ{sub}0+k.d{sup}(-1/2). k increases with plastic strain amplitude but stays lower than the values obtained under tensile loading. This aspect is discussed with guidance from qualitative and quantitative TEM observations and stress partitioning in terms of back (X) and effective stresses (Σ{sub}(ef)). More precisely, the back stress is partitioned into intragranular and intergranular long-range interactions. According to TEM observations, the interpretation of stress-strain quasi-plateau generally associated with the occurrence of Persistent Slip Band (PSB) is not suitable for the smaller grain size (18 μm). The quasi-plateau seems to be associated more with a competition between intergranular and intragranular back stresses than with the PSB formation in polycrystalline Nickel.
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