A statistical crystal plasticity model based on continuum dislocation dynamics and its application to the comprehensive analysis of microstructure evolution in copper during equal-channel angular pressing

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Abstract

During metal forming processes, especially those involving severe plastic deformation techniques, the grain structure of metals and alloys undergoes significant changes. At low homologous temperatures, the predominant mechanism of microstructural reorganization is fragmentation. This process occurs through the formation of dislocation cell blocks and their gradual evolution into subgrains and new fine grains via mutual rotations during deformation. Advances in computational capabilities over recent decades have increasingly enabled the application of mathematical modeling to analyze and optimize technological forming processes. To investigate microstructural transformations during these processes, multilevel constitutive models grounded in the crystal plasticity are particularly suitable. These models explicitly account for the evolution of internal structure and deformation mechanisms. This work proposes a novel multilevel statistical constitutive model based on continuum dislocation dynamics to describe grain fragmentation in face-centered cubic metals. The developed model comprehensively characterizes the fragmentation process by tracking the evolution of statistically stored dislocation and geometrically necessary dislocation densities, quantifying their influence on key microstructural parameters: average misorientation angle, average fragment size and average grain size in polycrystal. Model verification was performed against experimental data from four passes of equal-channel angular pressing of copper at room temperature via route Bc (workpiece rotation between passes). The model demonstrates satisfactory agreement with experimental results in predicting stress-strain states and critical structural parameters (grain size, crystallographic textures, disorientation angle and fragment size, dislocation densities).

Keywords

statistical crystal plasticity modelscontinuum dislocation dynamicsgrain fragmentationgrain refinementECAPgrain sizefragment sizestatistically stored dislocationsgeometrically necessary dislocationsfragment disorientation angle

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Article information

Published
8 December 2025
Issue date
8 December 2025
Issue
No. 4 (2025)
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