Strand Surface Temperature Along the Strand Cross Section
Figure 6 is the strand surface temperature along the cross section at straightening segment entry. In the figure, “0” is the corner between the wide face and narrow face of right-angle strand, while the corner between the wide face and chamfered face of chamfered strand. The temperature difference around the corner of the right-angle strand is much larger than that of chamfered strand. It may result in large thermal stress. And the temperature difference of the big-chamfered strand is
Fig. 6 Strand surface temperature along the cross section at straightening segment entry larger than that of multi-chamfered and fillet strand. The temperature of multi-chamfered and fillet strand has a relatively smooth shift in the strand surface. It is helpful to decrease the appearance of corner crack. The difference between the multi-chamfered strand and fillet strand is that the temperature of fillet strand in the chamfered face is lower than that of multi-chamfered strand.
In addition, both from Figs. 4 and 6, it can be seen that for the three kind of chamfered strand, the corner temperature between the wide face and chamfered face is obviously lower than that between the narrow face and chamfered face. On one hand, the angle of the corner between the wide face and chamfered face is smaller than that between the narrow face and chamfered face. On the other hand, the temperature of narrow face is higher than that of wide face near mold exit owing to the impact of nozzle jet. Besides, the secondary cooling water density on narrow face is much smaller than that on wide face.
Strand Central Temperature Under Different Mold Corner Structure
Figure 7 gives the strand central temperature change along the casting direction during the secondary cooling process. In the figure, “Right” means right-angle strand, “Big” means big-chamfered strand, “Multi” means multi-chamfered strand, “Fillet” means fillet strand. It shows that the central temperature of the right-angle strand is higher than that of chamfered strand and it solidifies fastest. There is little difference among the three kind of chamfered strand. The final solidification point of right-angle strand, big-chamfered strand, multi-chamfered strand and fillet strand is 22.1, 20.5, 20.4 and 20.2 m, respectively. It is clear that chamfer will speed up the heat transfer rate of the strand because of the increase of heat transfer area.
Fig. 7 Strand central temperature along the casting direction in secondary cooling zone