Papers by Keyword: Jerky Flow

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Authors: G. Ananthakrishna, S.J. Noronha
Authors: Miroslav Cieslar, P. Vostrý, Ivana Stulíková
Authors: B.J. Diak, Bert Verlinden
Abstract: An experimental AA5182 sheet was cold rolled 80%, and tensile specimens removed with orientations 0, 45 and 90 degrees to the rolling direction. Room temperature monotonic tensile tests were performed on the specimens in different recovered states obtained by isothermal annealing at 230°C from 0.1 to 10h. The tests were instrumented to measure instantaneous plastic strain ratio, and unloaded just after incipient necking, but before failure if possible. With annealing the flow curves are characterized by lower strains to the onset of jerky flow, the reappearance of yield point elongation, decrease in work hardening, and increasing ductility. The recovery in substructure was described using a constitutive parameter proportional to the mean slip distance.
Authors: Daria Zhemchuzhnikova, Mikhail Lebyodkin, Tatiana Lebedkina, Rustam Kaibyshev
Abstract: Stress serration patterns and kinematics of deformation bands associated with the Portevin-Le Chatelier (PLC) effect were examined for an Al–6%Mg–0.35%Mn–0.2%Sc–0.08%Zr–0.07%Cr (in wt.%) alloy with two grain sizes: 22 μm and 0.7 μm. The fine-grained structure of the alloy was obtained using equal-channel angular pressing (ECAP) at 320°C up to a total strain of ~12. Tensile tests were carried out at room temperature and strain rate ranging from 10-5 s-1 to 10-2 s-1. In addition, high-frequency local extensometry technique was applied to monitor the evolution of the axial strain distribution during deformation. Depending on the strain rate, conventional A, B, C, or mixed types of serrations were observed on the stress-strain curves. These types of behavior usually correspond to different kinematics of the PLC bands, including band propagation and localization. However, the propagation regime was found to dominate in the investigated alloy in the entire strain-rate range. This unusual behavior of deformation bands and their features depending on the grain size are discussed.
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