A procedure is offered and results of experimental evaluation of high-density pulse current effects on electrical resistance and relaxation of tensile elastic stresses are presented for a number of metallic materials. Based on analysis of experimental data, plastic strain rates are shown to be influenced by tensile stresses, current density, and temperature.Introduction. The passage of high-density pulse current through a metallic material is accompanied by a number of well-studied phenomena: increase in temperature, ponderomotive forces (pinch effect), current concentration near the surface of the material (skin effect), etc. [1][2][3]. However, such phenomena as relaxation of elastic stresses, the influence of loading conditions (applied stress levels and temperature) and pulse current parameters on its kinetics are still not clearly understood despite a substantial body of investigations made to date [2][3][4]. Earlier experimental investigations devoted to this problem were performed only for several materials and a limited range of loading conditions and current parameters. Thus, information is still inadequate to develop an effective pulse current treatment of metallic materials [3].The present communication covers a procedure and reviews results of experimental evaluation of the high-density pulse current effect on resistivity and relaxation of tensile elastic stresses. The tests of specimens in the form of long narrow metallic strips in tension provided results whose analysis allows assessment of the direct (nonthermal) current effect and refinement of the tensile elastic stress and current density effects on the plastic strain rate.It also presents results of experimental evaluation of nonlinear pulse current density effects on resistivity for a number of metallic materials.Scheme of Specimen Loading. Pulse current effects on tensile stress relaxation were studied on St. 3 low-carbon steel, copper, molybdenum, and tantalum specimens in the form of strips up to 350 mm long with a ( ) 2 6 × -mm [or ( ) 1 6 × -mm] cross-section. The specimens were mechanically loaded in an IR-50 test machine where

Results of experimental evaluation of the pulse current effect on stress levels in a stretched steel strip are presented. At the stage of growing loads, stress relaxation in the strip is shown to increase with current densities and loads. After a stepwise decrease in loads, pulse current passage causes an increase in tensile stresses rather than their relaxation. It was suggested that loading and further unloading result in microplastic strains of different directions, which become apparent upon pulse current passage. The phenomenological model of the metal behavior describing the pulse current effect upon loading and unloading is proposed.Keywords: pulse current, stress-strain state, stress relaxation, phenomenological model of the material.Introduction. The passage of high-density pulse current through a metallic material brings about an increase in temperature, ponderomotive forces (pinch effect), current concentration near the surface and in the vicinity of defects as well as other phenomena, including the electroplastic effect [1][2][3][4][5][6][7]. However, the behavior of the metal at the stages of growing mechanical loads and further unloading accompanied by pulse current passage is as yet imperfectly understood.The present communication covers the results of experimental studies on the effect of high-density pulse current on the relaxation of tensile stresses in a low-carbon steel strip in uniaxial tension. Such tests make analysis of results easier and ensure reliable evaluation of pulse current effects on the stress-strain state of the metal.Experimental Procedure. The pulse current effect on stress relaxation in a metal strip with an increase or decrease in tensile loads was studied on the specimens in the form of St. 3 low-carbon steel strips with a 2 6 × -mm

Translated from Problemy Prochnosti, No. 1, pp. 39 ??? 46, January ??? February, 2012Experimental results of evaluating the pulsed electromagnetic field effect on tensile stress relaxation in specimens with hole a concentrator are presented. The pulsed electromagnetic field is shown to induce local inelastic strain of a metal in the vicinity of the concentrator, which is greatly dependent on pulsed field parameters and concentrator sizes, determining the ratio of thermal-nonthermal current effect

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