Atypical behavior of materials during current-assisted tension

Abstract

The passage of electric current in conductive materials is accompanied by a variety of physical phenomena, one of which is the so-called electroplastic effect, which manifests itself in a decrease in flow stresses and an increase in plasticity. Despite the early discovery of the electroplastic effect, the proposed mechanisms could not fully explain the observed experimental facts. Moreover, as shown in this study, some modes / regimes of electric current can lead to atypical strengthening phenomena even in pure metals and to atypical upward stress jumps in alloys with phase transformations. The paper considers examples of strengthening under a pulsed current with a density greater than the critical one and a duty cycle of more than 10 3 in pure metals, shape memory alloys, ferrite-pearlitic and stainless steels. It is assumed the selected current regimes provide the minimum thermal effect and maximum stress relaxation. The literature data and the results obtained, suggests that among the possible causes of strengthening there may be structural changes (recrystallization and refinement of grains, transformation of lamellar phases into spherical ones), martensitic transformation. It is concluded the atypical current effect is due to the material nature and high duty cycle of the electric current.