Analysis on tracer transport process and casting of different steel grades in a 12-strand billet tundish
In response to the phenomenon of grade transition casting in the tundish,the 12-strand tundish of a certain factory is selected as the research subject.Numerical simulation methods are employed,and based on the steady-state flow field of the tundish,the evolution of the tundish flow field and the grade transition casting process are simulated by pulsing and continuously adding tracers.The time that tracer starting to flow out of tundish and flow out percentge of each outlet were calculated by using the analysis method of outflow percentage.The standard of steel grade transition was based on the proportion of difference between the new and old heat of molten steel concen-tration reaches 20％-80％.It was calculated that when the tracer was pulsed or continuously added,the starting change time of the concentration of far away strand 5 and 6 was much longer than that of strand 1 to 4,and the difference was significant.The length of transition billet for strand 1 to 6 is 52.127 m,68.040 m,66.411 m,72.011 m,87.174 m and 88.702 m,respectively.When the concentration of strand 1-6 reaches 80％(to meet the composition requirements of new steel grades),the total accumulated weight of molten steel is 104.152 t,134.244 t,133.925 t,147.715 t,200.698 t and 247.135 t,respectively.The far away strand 5 and 6 requires more than the weight of a ladle of molten steel(150 t)to meet the requirements of the new steel grade.There are great differences between the different strands of the 12-strand tundish during grade transition casting,so different criteria of transi-tion billet should be adopted in production.
grade transition castingtransition billet12-strand tundishnumerical simulationtracer transport
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