The Effect Of Final Electromagnetic Stirring To Solidification Structure Of Bloom

With the rapid development of modern automobile industry, productivity andquality of thetire cord steel is highly required. Improving the quality of80tire cordsteel is the research emphasis in related fields.80tire cord steel is a high-carbon steeland its blooms have serious center segregation, shrinkage, porosity and other defects.The solidification structure and defects in casting billet may inherit to the subsequentmicrostructures of steels and that may affect the structures and properties of the steels.The effect of electromagnetic stirring of solidification end on the microstructure of80tire cord steel was studied by numerical simulation and experiments. A three-phaseand three-pole rotary agitation on a magnetic stirrer was designed and athree-dimensional finite element model of the electromagnetic field was built by usingANSYS software.Electromagnetic fields under no-load conditions were calculated.Atthe same time, the magnetic induction intensity in the stirrer center under no-loadconditions was measured. After checking, the results of numerical simulation ofmagnetic induction intensitywere consistent well with the measured results. Theinfluences of power frequency and current intensity on the magnetic inductionintensity and electromagnetic force were analyzed under no-load and load conditions.Results showed that the electromagnetic force and the magnetic induction intensityincreased with the increasing of current value and frequency under the same loadcondition. While the joule heat on the slab surface generated by the induced currentincreases significantly with the increasing of the intensity of electric current.With theincreasing of frequency, magnetic induction intensity and electromagnetic force incenter position decreased seriously. Simulation results showed that the distribution ofelectromagnetic force in liquid-core part of slab is better when the agitator current isaround500~600A and the frequency is4~6Hz. The electromagnetic parameters ofsolidification end in80cord steel during continuous casting process were settedaccording to the simulation results and on-site casting experiment was conducted. Asa result, the solidified structure in slab center was refined significantly, the centersegregation of carbon and sulfur was reduced, and the amount of center shrinkagecavity and the volume of porosity were decreased due to the end electromagneticstirring with the agitator current of600A and the frequency of5Hz.