Dislocation structure evolution under electroplastic effect

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 761; p. 138026
• Main Authors: Xiang, Siqi, Zhang, Xinfang
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 22.07.2019; Elsevier BV
• Subjects: Dislocation density; Dislocation pinning; Dislocation structure; Drift; Electron wind force; Electrons; Electroplastic; Evolution; Frank-read source; Multiplication; Ohmic dissipation; Plastic deformation; Plastic flow; Residual stress; Resistance heating; Side effects; Strain; Thermal expansion; Wind forces; Dislocation structure; Electron wind force; Frank-read source; Electroplastic; Residual stress
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2019.138026

In this study, the effect of high current density electropulsing (103 A/mm2 for 150 μs) on the residual stress of quenched steel was investigated with the objective of determining the electroplastic effect on plastic strain and dislocation evolution. The residual stress and dislocation density, which were closely related to the plastic strain, were significantly reduced through electropulsing. The direct effect of drift electrons on the dislocation motion, instead of side effects such as skin, pinch, instantaneous thermal expansion stress, and Joule heating, primarily contributes to the plastic strain. Employing the thermally activated plastic flow concept, the drift electrons were also found to have an effect on the thermally activated dislocation motion in addition to the force exerted on the dislocations by an electron wind. Under the action of drift electrons, the movement of vacancies and dislocations were enhanced, which accelerated the dislocation annihilation. In contrast, affected by the electron wind force, Frank-Read source failed to produce a large amount of dislocations, thereby simultaneously decreasing the dislocation multiplication rate. Finally, the dislocation density decreased and the dislocation structure was rearranged parallel to the direction of motion of the drift electrons.