PSI - Issue 65

A.Y. Morkina et al. / Procedia Structural Integrity 65 (2024) 158–162

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Morkina A.Y., et al. / Structural Integrity Procedia 00 (2024) 000–000

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3. Results

The experiment consisted of passing 15 high-density current pulses with different fixed tensile stresses in the range of 34-76 MPa. This load range covers both the elastic and plastic deformation regions. The capacitor bank voltage was chosen to be 75 V. At this voltage, the specimens heats up by only 17 °C, which is 1.8% of the melting point of aluminum.

Fig. 3. The increase in plastic deformation as a function of the electric current pulse number at various values of the fixed tensile stress.

Fig. 3 shows the results of the experiment, where the pulse number is plotted along the abscissa axis, and the deformation caused by a given current pulse is plotted along the ordinate axis. At tensile stresses of 34-52 MPa, the electroplasticity effect is practically not manifested, since this stress range is in the region of elastic deformations. But with an increase in tensile stresses, the electroplasticity effect becomes more obvious. The first current pulse produces the greatest deformation of the specimens, and with each subsequent pulse this effect weakens until saturation occurs. This may be due to the fact that dislocations, the movement of which is activated by the current pulse, stop at defects in the crystal lattice. In this case, the proportion of mobile dislocations decreases from pulse to pulse, which leads to a decrease in the increase in plastic deformation with the pulse number. It is also evident that the higher the tensile stresses, the more the specimens is deformed. After this experiment, the structure of the specimens was checked and it was found that the electroplastic effect did not affect it, since the heating of the specimen was only 17 °C, which was mentioned earlier. A study was conducted on the effect of high-density electric current pulses on the deformation of aluminum specimens of the KAS 8176 brand. It was found that the first current pulse produces the greatest deformation, and with each subsequent pulse the deformation becomes less and less until it reaches steady-state creep. This can be explained by the fact that the heating of the specimen occurs non-uniformly and most of the heat is released at dislocations due to which plastic deformation occurs. However, dislocations gradually reach other defects of the crystal lattice. It was also found that the current pulse treatment did not affect the structure of the specimen, since the heating was insignificant. Therefore, the electroplasticity effect may be promising for the deformation of metals with a pre prepared structure and properties. 4. Conclusion