| Ductile iron casting alloy date from the last 1950 s,it had become one of the important materials in the world casting industry. Ductile iron has excellent casting and machining performance, it was widely used in automotive, residential construction,petrochemical, agricultural machinery, rail transportation and other fields. Therefore, the solidification structure and microstructure morphology of ductile iron research had important significance.This paper aims at improving QT700-2 ductile iron solidification structure, using electrical pulses to refine the size of coagulated tissue technology to improve the organization of the rate of the ball, pearlite content and mechanical properties, to study the influence of different parameters on the pulse current ductile iron QT700-2 in solidification.This paper study from the electric field distribution inside the melt under ductile electrical pulses through ANSYS software simulation, The influence of factors on the distribution of electric field intensity in the melt was studied,what include the depth of electrode deployment,electrode diameter, the distance between two electrodes, insert mode of electrode. Based on computer simulation results of the graphite electrode inserted from the top of the melt showed that pulsed electric field major role in the electric field intensity melt surface electrodes near the maximum,electric field strength away from the electrode is relatively small, and the influence due to the mutual inductance between the electrodes, so that the current between the two electrodes is relatively large; and increases with the increase of the distance between the graphite electrode diameter graphite electrode, inside the melt pulsed electric field depth increases, the electric field intensity distribution, skin effect weakened; graphiteelectrode inserted vertically inside the melt, there is a critical depth of insertion. From the effects of three different electrode insertion of the internal electric field intensity distribution of the melt, drawn from both ends of the graphite electrode inserted into the melt, the melt strength of the electric field inside the largest scope, most distributed evenly, surface shunt is improved.Experiments by applying a pulse current ductile iron solidification process QT700-2 ductile iron solidification process, using orthogonal experiment of different parameters on the pulse of electrical pearlite cast ductile iron solidification structure and properties by using the optical microscope for pearlite ductile cast iron graphite shape and matrix structure were observed and analyzed by scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS) of the graphite material and the ball nucleation lamellar structure before and after the pulse current handling pearlite analyzed. Results can be found through the study that fter the electric pulse treatment,the rate of ductile iron ball, pearlite number had increased to some extent, by comparison, the effect of sample processing best it is good after the electric pulse parameters are 1100 V, 0.88 Hz, 2 300μF. 1/4 position of the sample in the test piece(near the electrodes) sampling, the study found after the electric pulse treatment, 1/4position of the specimen at the center of the sample compared to the position, the ball was increased even more sharply, graphite the more the number of balls and smaller particle size; and the hardness and pearlite content is substantially unchanged before and after pulsed electric ball-shaped graphite nuclear materials are oxides.By tensile tests of ductile iron can be drawn only after a pulsed electric Ductile Iron tensile strength is increased by the untreated 718.082 MPa treated 723.313 MPa, rear extension rate fell 8.13% to 5.85%. Tensile fracture SEM showed that the untreated samples exhibit ductile QT700-2 characteristics of quasi-cleavage fracture, but only after a electrical pulse processing, sample fracture surface showing cleavage fracture characteristics. |
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