Effect Of Electric Current Pulses Research Articles

Development of a method for measuring pulse currents of large magnitude

The paper presents the results of a study on the search for correct methods for measuring a high-value current pulse, which will be used to conduct research on the electroplastic effect. The electroplastic effect is the effect of electric current pulses on the plastic flow of metals. Electroplastic metal forming technology is a relatively new metal forming process that is energy efficient, environmentally friendly and versatile. In particular, it can be used to process metals or alloys that are difficult to process using conventional manufacturing processes. For the experimental study of the electroplastic effect, it became necessary to measure pulse currents of large magnitude, not only in amplitude, but also in the shape of the pulse. The pulsed current causes the formation of an alternating electromagnetic field near the conductors, so it can be measured with a Rogovsky current transformer. The results of the work present a schematic electrical diagram and a photograph with the appearance of an experimental installation for the study of the electroplastic effect. The results of measurements of the current value, the voltage drop on the sample and the dependence of the peak voltage values on the sample on the peak current value are shown. After making calculations and renormalising the data for the voltage drop on the sample according to the peak value of the current obtained on the transformer, the authors obtained the desired current values. The error of this method is estimated by calculating the total capacitance of capacitors, which does not exceed 2%.

Microstructure Evolution of the Pb–Al Alloy Solidified Under the Effect of Electric Current Pulses

Microstructure Evolution of the Pb–Al Alloy Solidified Under the Effect of Electric Current Pulses

Effect of electric current pulses on TiB2 particle dispersion in aluminum alloy melt

The effect of electric current pulses (ECPs) on the dispersion of TiB2 particles is investigated. The results demonstrate that Joule heating and the Peltier effect can reduce the binding force between TiB2 particles in the melt. The induced magnetic pressure, pinch force gradient and electromagnetic shock wave can disperse loose aggregations of TiB2 particles, thereby decreasing the size of the TiB2 particle clusters. The ECP parameters are found to have a large influence on the TiB2 particle cluster dispersion.

Numerical Modeling and Experimental Verification for High-Speed Forming of Al5052 with Single Current Pulse

Application of electric current pulses during plastic deformation changes the mechanical behavior owing to the electro-plastic effect. The effect of electric current pulses on the Al5052 alloy is investigated in this study. In order to demonstrate the advantages of passing electric current pulses through a metal sheet during the forming process, a uniaxial tensile test with an electric current pulse was carried out using a self-designed device; this device can apply a 2-kA electric current pulse to the specimen for a short period (>100ms). The electric current increases the temperature of the specimen due to Joule heating. It is, therefore, necessary to decouple the thermal effect from the overall behavior to understand only the contribution of electric current in the mechanical behavior. Firstly, an electro-thermo-mechanical finite element study of an electrically assisted uniaxial tensile test of Al5052 alloy is performed to isolate the thermal effect. The simulated results yielded the thermal effect due to the electric current. By comparing the experimental and simulated results, the contribution of electric current is decoupled from that of thermal effect. The electric current-dependent material model is implemented into the commercial FEM code LS-DYNA using user-defined material(UMAT) subroutine. The electric current-dependent material model was used to simulate the electro-mechanical finite element analysis of the high-speed forming of an aluminum sheet with electric current pulse. Simulation results were compared with experimental results at several applied electric currents to evaluate the accuracy of the UMAT. The present work can be utilized to develop simpler constitutive models for the mechanical behavior of metals subjected to a pulsed electric current.

Electric current control of creation and annihilation of sub-100 nm magnetic bubbles examined by full-field transmission soft X-ray microscopy

The effect of electric current pulses on a sub-100 nm magnetic bubble state in a symmetric Pt/Co multilayer was directly observed using a full-field transmission soft X-ray microscope (MTXM). Field-induced evolution of the magnetic stripe domains into isolated bubbles with their sizes down to 100 nm was imaged under varying external magnetic fields. Electric current pulses were then applied to the created magnetic bubbles, and it was observed that the bubbles could be either created or annihilated by the current pulse depending on the strength of applied magnetic field. The results suggest that the Joule heating plays a critical role in the formation and/or elimination of the bubbles and skyrmions. Finally, the schematic phase diagram for the creation and annihilation of bubbles is presented, suggesting an optimized scheme with the combination of magnetic field and electric current necessary to utilize skyrmions in the practical devices.

Effect of electric-current pulses on structural changes in cold rolled copper at different initial temperatures

The influence of external current electric fields on the mechanical properties of metals and alloys has been studied for a long time. The effects of electric-current pulses (ECPs) on materials structure were attributed to an increase in the mobility of dislocations in the presence of the electric current (an effect sometimes referred to as “electron wind”) and subsequent acceleration of the formation of recrystallization nuclei. At the same time, it has been demonstrated that the Joule heat induced by ECP has some impact on the recrystallization microstructure of the material. What makes the dominant contribution to the structural changes taking place in the material, Joule heating or "electron wind", remains still unclear. The aim of this work was to determine the effect of Joule heating by electric-current pulses on the evolution of grain structure at different initial temperatures in copper specimens. For this purpose, copper samples were rolled to a 90% thickness reduction and then pulsed at two initial temperatures of the specimens, 20°C and -170° C, the latter being achieved by cooling with liquid nitrogen. As the integral current densities 0.449 × 105 A2s mm-4 for initial room temperature and 1.052 × 105 A2s mm-4 for initial temperature -170oC were attained, the material was recrystallized completely. The microstructural changes are compared to similar observations for static recrystallization and explained in terms of Joule heating.

Effect of electric current pulses on the microstructure and niobium carbide precipitates in a ferritic-pearlitic steel at an elevated temperature

Abstract

Effect of Electric Current Pulses and Cryogenic Temperatures on the Strength of Cutting Hard-Alloy Plates

The effect of current pulses and deep freezing down to a temperature of 77 K on the bending strength of cutting hard-alloy plates was investigated. The efficiency of different conditions of their modification was verified.

The effect of electropulsing on the interlamellar spacing and mechanical properties of a hot-rolled 0.14% carbon steel

The application of electropulsing treatment to a low carbon ferritic–pearlitic steel is studied. The effect of electric current pulses on the interlamellar spacing of pearlite is investigated. It is found that the interlamellar spacing increases as the number of pulses increases. The mechanism of electropulse-effect was discussed by analysing the change in the free energy and the reduction of electrical resistance due to electropulsing. Mechanical properties are also examined for the samples with and without electropulsing treatment. It is shown that softening occurs during the treatment which is attributed to the formation of precipitation free zone (PFZ), increase in the value of interlamellar spacing and the spheroidization of the lamellar structure.

Effect of electric-current pulses on grain-structure evolution in cryogenically rolled copper

Abstract

Effect of electric current pulses on solidification of immiscible alloys

The effect of electric current pulses (ECPs) on the solidification of immiscible alloys is investigated. The results demonstrate that ECPs mainly affect the microstructure formation through changing the nucleation behaviors of the precipitated phase droplets (PPDs). When the PPDs have a higher electrical conductivity compared to the matrix, ECPs enhance the nucleation rate and promote the formation of a well-dispersed microstructure. Otherwise, ECPs cause a decrease in the nucleation rate and promote the formation of a phase segregated microstructure.

Anisotropy of the mechanical characteristics of steel under the effect of electric current pulses and cryogenic temperatures

The article deals with the influence of high-density electric current pulses on the anisotropy of the mechanical characteristics and of the electrical resistance of the austenitic steel 07Kh13N4AG20 in the temperature range 293-4.2 K. It was established that electric current pulses have a strong influence on the anisotropy of the mechanical characteristics of the steel. The article shows that there exists a stable correlation between the degree of anisotropy of the mechanical characteristics and of the electrical resistance.

Effect of electric current pulses on fatigue characteristics of polycrystalline copper

Electric current pulses (about 10 4 A cm −2 for 100 μs and 2 s −1) applied during rotating bending fatigue tests on polycrystalline copper produced the following effects: (a) an increased fatigue life, the magnitude of which became larger with a decrease in stress, (b) a reduced intergranular relative to transgranular cracking and (c) increased homogenization of slip. The former two effects were attributed mainly to the increased slip homogenization. The results are evaluated in terms of dislocation models pertaining to fatigue life and mode of cracking.

Effect of electric current pulses on the development of failure of steel 03Kh20N16AG6 at 4.2 K

The article presents the results of the experimental investigation of the special features in the development of failure of steel 03Kh20N16AG6 at 4.2 K. It shows that the local maxima of load observed to the left of the five-percent secant on the stress-displacement diagram are associated with the formation of a plastic zone at the crack tip by jumplike low-temperature deformation. It was established that the unstable crack development corresponds to a local maximum of load coinciding with the point of intersection of the five-percent secant with the load-dis-placement diagram or found immediately after it. Electric current pulses stimulate plastic deformation at the crack tip in the loaded specimen. Here the plastic zone forms without jumps of the load, and already the first observed local maximum corresponds to unstable crack development.

The Effect of Electric Current Pulses on the Dislocation Mobility in Zinc Single Crystals

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Resistance of metallic materials to the plasticizing effect of electric current pulses

Resistance of metallic materials to the plasticizing effect of electric current pulses

Effect of electric current pulses on the recrystallization kinetics of copper

Effect of electric current pulses on the recrystallization kinetics of copper

Special features of deformation and fracture of 12Kh18N10T and 03Kh13AG19 steels under the effect of electric current pulses and cooling to 4.2�K

The authors examine the deformation and fracture resistance of structural materials in the conditions of constant loading and the effect of electric current pulses at cryogenic temperatures. The steels 12Kh18N10T and 03Kh13AG19 were tested.

A comment on “effect of electric current pulses on the recrystallization of copper”

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Effect of electric current pulses on the recrystallization of copper

Effect of electric current pulses on the recrystallization of copper