Effect Of Electric Pulse Treatment On Low Temperature Microstructure Of Eutectic Iron And Carbon Alloy

In this paper, the hypoeutectic Fe-C alloy with3.09%wt carbon was treated by electric pulse in different technological parameters. It studied the effects of different initial temperatures, voltages, frequencies and pulse widths on the modified ledeburite, graphite, ferrite and pearlite of the microstructure of the hypoeutectic Fe-C alloy. At the same time, the influence mechanism of electric pulse treatment on the microstructure of the hypoeutectic Fe-C alloys was primary analyzed.After applying electric pulse treatment on the hypoeutectic Fe-C alloy, it reduced the modified ledeburite, accelerated the diffusion of carbon atoms, and promoted the nucleation and growth of graphite. It also made the lamellar spacing of pearlite shorten and the cementite lamellar of pearlite became thinner and shorter. Experiment showed that the electric pulse treatment applied on the eutectoid line under low voltage electric pulse was better than the room temperature, and increased with the increasing of the voltage. The graphite nucleation rate of room temperature treatment was obviously higher than that of eutectoid temperature line with the electric pulse treatment, and the latter of graphite size in the microstructure was less than that of the former. Furthermore, the relative content of ferrite of room temperature treatment was obviously more than that of eutectoid temperature line with the electric pulse treatment. Otherwise, the effect of pearlite on eutectoid line with electric pulse treatment was significantly better than that of the room temperature.The effect of the pulse treatment parameters on the microstructure of the hypoeutectic Fe-C alloy was studied through the single variable method. The study found that the volume fraction of modified ledeburite in the microstructure of the hypoeutectic Fe-C alloy decreased with the increasing of the voltage of the electric pulse treatment, the quantity of graphite increased with the increasing of the voltage, and the average size of graphite first and then decreased with the increasing of voltage. The volume fraction of modified ledeburite in the microstructure of the hypoeutectic iron-carbon alloy decreased with the increase of the pulse frequency, the number and average size of graphite increased with the increasing of pulse frequency, and the volume fraction of modified ledeburite of the hypoeutectic Fe-C alloy reduced with the increasing of pulse width of pulse treatment power, the number and average size of graphite was proportional to the increasing of the pulse width. It was found that the voltage of electric pulse treatment affected the most obvious, the pulse width followed and the pulse frequency was the last.The research discovered that the effects of the electric pulse treatment on the microstructure of hypoeutectic Fe-C alloys was the joint of various effects of electric pulse treatment. The electromigration phenomenon and the electronic wind, which produced by the electric pulse treatment were the most important. Furthermore, when the electric pulse treatment applied at room temperature, The Joule heating effect is also one of the important influence factors.