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Effect of Mold Corner Structure on the Strand Corner Temperature
Figure 4 compares the cooling trend of strand corner temperature among the four kind of strand. In the figure, “w” means the corner between the wide face and the chamfered face, while “n” means the corner between the narrow face and the chamfered face. And “c” means the corner between the two chamfered faces in multi-chamfered strand. It is evident that the corner temperature of the right-angle strand is the lowest in secondary cooling zone. On one hand, the right-angle structure will make the cooling faster because the heat transfer angle of right-angle strand is larger than that of chamfered strand. On the other hand, the corner temperature of right-angle strand at mold exit is much lower than that of chamfered strand. Besides, when corner structure changed from right-angle to big-chamfer, the rise of corner temperature was much higher than that changed from big-chamfer to multi-chamfer or fillet. Therefore, it is very effective to improve the corner temperature in secondary cooling zone through using chamfered mold. Although multi-chamfered mold and fillet mold may increase the corner temperature further, it is not remarkable relatively.
The corner temperature variation in straightening segment is shown in Fig. 5. The entry and exit corner temperature is presented in Table 3. It is clear that the corner temperature of right-angle strand in straightening segment is between 1037 K and 1064 K, which is in the low ductility temperature zone. The strand may have corner cracks under the influence of thermal stress and straightening stress. The corner temperature of chamfered strand is about 100 K higher than that of right-angle strand, which will avoid the low ductility temperature zone. It is very useful to prevent corner cracks. Moreover, when corner structure changed from big-chamfer to multi-chamfer or fillet, the rise of temperature is less than 20 K.
Fig. 4 Strand corner temperature along the casting direction in secondary cooling zone
Fig. 5 Strand comer temperature along the casting direction in straightening segment
Table 3 The entry and exit corner temperature of straightening segment
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