Control of temperature of high-Ti steel on top surface and"floater"formation
During the production of the high-Ti steel,TiN inclusions formed under the reaction of the tatinium and nitrogen in the liquid steel,and aggregated near the steel-slag interface,which easily resulted in the formation of the"floater"on the steel-slag interface at the low-temperature zone and then the troubled continuous casting.The nu-merical simulation was established and used to solve the problem of the"floater"formation in the continuous casting mold during the casting of high-Ti steel.In order to reduce the formation of"floater"in the mold by increasing the temperature of the steel on the surface,the influence of the current by the electromagnetic stirring,casting speed and casting superheat on temperature of the steel on the surface was discussed,and the adjustment of the basicity of the mold slag was conducted.Through mathematical simulation,it is found that the temperature of the steel on the surface can be raised by the application of the electromagnetic stirring equipment in the mold with the casting speed of 0.85 m/s and 1.05 m/s,and the temperature is the highest with the stirring current of 200 A.With the current of the electromagnetic stirring constant,the increase of the casting speed and casting superheat can result in the in-crease of the steel temperature on the surface and the decrease of the size of the low temperature zone at the corner of the mold.Through the trial in the steel plant,it is found that with the casting superheat increasing from 25 K to 60 K,the formation of"floater"did not occur in the mold,and the slag-entrapment defects on the surface of contin-uous casting billet were significantly reduced when the continuous casting parameters except the casting speed were constant.With the basicity of continuous casting mold slag increasing from 0.60 to 0.88,the ability of crystalliza-tion and the heat-transfer control increased,and during the trial in the steel plant the thickness of liquid slag in-creased from 6 mm to 8 mm,which indicates that the temperature of liquid steel on the surface increased.Besides,the"floater"also did not occur with the application of the optimized slag during the low-superheat casting(40 K).Hence,the formation of"floater"in the continuous casting process of high-titanium steel was affected by the tem-perature of the liquid steel at the surface,and the formation of"floater"in the mold could be reduced by increasing the casting superheat and improving the control ability of the heat transfer of the continuous casting slag.The opti-mized slag could be used for the casting of high-titanium steel with low superheat,and would provide theoretical guidance for improving the casting ability of high-itanium steel.
high-Ti steelcontinuous casting moldfloatersteel temperature on the surfacenumerical simulation
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