Funct. Mater. 2019; 26 (3): 484-488.

doi:https://doi.org/10.15407/fm26.03.484

Dislocation-kinetic approach to the description of the strain hardening of flat plate polycrystalline specimens of pure metals

E.E.Badiyan, A.G.Tonkopryad, Ye.V.Ftomov, O.V.Shekhovtsov

V.Karazin Kharkiv National University, Svobody Sq. 4, 61022 Kharkiv, Ukraine

Abstract: 

The dislocation-kinetic approach is used to describe strain hardening up to the stage of developed plastic strain under uniaxial tension conditions at moderate temperatures of flat plate polycrystalline specimens of pure metals with a thickness and average grain size in the range from ~ 50 μm to macroscopic values. Due to the specificity of flat specimens, the strain hardening effect of "vertical" boundaries in the surface layer of grains and the role of the free surface of a flat plate specimen as a source and sink for dislocations were taken into account when calculating the coefficients of the kinetic equation. It was also taken into account that with the above values of the average grain size, the mechanism of dislocation multiplication on forest dislocations contributes to the accumulation of dislocations, in contrast to nanocrystalline specimens. The results of the tensile stress-strain curves calculations correspond to the experimental data for different values of the average grain size and thickness of flat plate polycrystalline specimens of pure aluminum (99.999 at.%).

Keywords: 
strain hardening, dislocation kinetics, tensile stress-strain curve, flat plate polycrystalline specimens.

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