| Bridges,tunnels,machinery,military industry and other industries requiring large cross-section billet developed with the rapid development of modern China's economy.The demand for large cross-section steel in these industries is increasing day by day,and the steel quality is also beginning to improve,so it is urgent for the steel industry to improve the output and quality of billet.At present,the billet produced by continuous casting still has defects,such as shrinkage porosity,shrinkage cavity,cracks and so on.In this paper,electromagnetic swirling method is used to control the quality of billet.In this paper,the electromagnetic swirl is applied to the nozzle structure of continuous casting,which causes the change of molten steel flow state in the mold,thus changing the temperature field distribution in the mold.In order to improve the casting billet product quality to improve the theoretical basis.Firstly,the principle and advantages of electromagnetic swirling at the nozzle are analyzed,and the technological parameters of continuous casting are preliminarily set.The electromagnetic field model is established,and the electromagnetic force of the electromagnetic swirl is controlled by changing the intensity of the applied current,and the electromagnetic force obtained by using the theoretical formula is compared to verify the correctness of the electromagnetic force simulation.Secondly,according to the corresponding calculation formula of continuous casting,the length of mold,the initial casting speed,the physical parameters and the high temperature mechanical properties of the casting billet are obtained.The solidification heat transfer model of 400mm×600mm extra-large rectangular billet was established,and the electromagnetic force of the simulated electromagnetic swirl was applied as the boundary condition on the nozzle of the solidification model of rectangular billet.The flow field and temperature field of molten steel in rectangular billet crystallizer are simulated by comparing different electromagnetic forces.The influence of electromagnetic cyclone on rectangle billet is analyzed.Then the normal straight nozzle is changed into a bell nozzle,and the electromagnetic force of electromagnetic swirl is generated by applying different current intensities to simulate the flow field and temperature field in the crystallizer.By comparing with the flow field and temperature field of the ordinary direct nozzle,the advantages of the bell nozzle in the continuous casting with electromagnetic swirling flow are analyzed.The influence of the drawing speed on the flow field and temperature field in the crystallizer was analyzed by changing the drawing speed under the nozzle of the bell.Last two dimensional elastoplastic model is set up,under different degree of superheat and drawing speed will simulate the liquid steel temperature as a condition of load on the two-dimensional elastoplastic model,the slab solidification shrinkage in the crystallizer of the change of stress and strain,analysis under different process parameters,slab crack index changes,validation based on the casting speed and superheat is in line with the actual production requirements. |
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