JPS61276750A - Horizontal and continuous casting method for metal - Google Patents

Abstract

PURPOSE:To form the finer crystal grains and to prevent the internal cracking of an ingot by cooling a molten metal supplied into a water-cooled casting mold from a tundish in such a manner that said steel forms a solidified shell in the mold without forming the solidified shell in a feed nozzle. CONSTITUTION:The feed nozzle 1 of the horizontal and continuous casting method for steel consisting in supplying the molten steel from the tundish (not shown) onto the water-cooled casting mold 6 through the feed nozzle 1, cooling and solidifying the molten metal with a lubricating sleeve 4 and drawing the solidified shell obtd. in such a manner as the ingot 5 toward the arrow direction is constituted of a refractory heat insulating brick and a slit 2 is provided to the outside surface thereof to decrease the heat transmission area. The cooling of the molten metal in the nozzle 1 is thereby prevented by which the formation of the solidified shell is prevented. The molten metal is quickly cooled on the mold 6 and a solid/liquid boundary 3 is quickly raised to form the solidified shell. As a result, the finer crystal grains are formed and the grain boundary cracking is prevented. The ingot 5 having no internal cracks is thus obtd.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a method for horizontal continuous casting of metal, and more specifically, to a horizontal continuous casting method for metal, which can prevent internal cracking of an ingot in horizontal continuous casting of metal. Continuous use method.

[Prior art 1] In general, cracks in phosphorus-deoxidized copper S ingots occur during horizontal continuous casting.
It occurs at coarsely developed columnar grain boundaries (Reference Figure 2 (
(See photos in a) and (b)).

The reason for this coarsening of grains is that in horizontal continuous casting, a solidified shell is formed from the weakly cooled feed nozzle part closer to the tundish than the water-cooled mold part, and the cooling rate of this part is low.

That is, in the horizontal continuous metal casting method shown in FIG.
It reaches the lubricating sleeve 4 and is immediately cooled by the water-cooled mold 6 to become the II lump 5, but a solidified shell is formed at the solid/liquid interface solidified grain forming part in the region 3' where the cooling rate is low. Then, it moves to the solid/liquid interface where the cooling rate is high as shown in 3. As mentioned above, a solidification shell is formed in the portion where the cooling is small and the columnar crystals become coarse.

To further explain this with reference to FIG. 8, it can be seen that when the cooling rate during solidified shell formation is low, the crystal grains of the ingot become coarse in the vicinity of the solidified shell.

The grain size of the columnar crystals is determined by the number of nucleations determined by the cooling rate during solidification shell formation, and if the cooling rate is small as shown in Figure 9(a), no nucleation will occur as indicated by the X mark. The grains become active and coarse;
When the cooling rate is high as shown in Figure (b), the nuclei marked with X are actively generated, resulting in fine crystal grains.

In the past, in order to increase the cooling rate when forming a solidified shell in horizontal continuous casting of metal, it was considered to increase the heat absorption ability of the solidified shell forming part, and as shown in Fig. 10, metal supplied from a tanditshu was The molten metal flows from the feed nozzle 1 and is cooled by the cooling nozzle 7 where it comes into contact with the lubricating sleeve 4, and then immediately comes into contact with the water-cooled mold 6 through the sleeve 4, resulting in 1Qi5. In this case, the solid/liquid interface becomes similar to that explained in Fig. 7, and the solidified shell forming part simply moves further to the tundish side of the feed 7 nozzle 1, and the effect of improving the cooling rate cannot be obtained. In this case, the long thin solidified shell cracks when the ingot 5 is pulled out, damaging the surface quality.

[Problems to be Solved by the Invention] The present invention was made in view of the various problems of the conventional horizontal continuous casting method as explained above. It has been found that the occurrence of grain boundary cracking is reduced or eliminated as the crystal grains become finer, and that the formation of solidified shells in which nucleation is inactive in areas where the molten metal is cooled can be prevented. He developed a casting method.

Means for Solving Problem E 1 The feature of the horizontal continuous metal casting method according to the present invention is that in continuous metal casting, the molten metal supplied from the tundish is passed through the feed nozzle without forming a solidified shell. , cooling to form a solidified shell in a water-cooled mold.

The method for horizontal continuous casting of metal according to the present invention will be explained in detail below using examples shown in the drawings.

Figure 1 shows a refractory insulating brick nozzle 1 with a lubricating sleeve 4 (ingot 51) in order to prevent the formation of solidified shells in the part near the tundish where the cooling rate is slow. The case is shown in which the nozzle 1 is attached to the water-cooled mold 6 through a sleeve made of fireproof and insulating brick, but it cannot be removed by simply attaching the nozzle 1 made of fireproof and insulating brick because it prevents the nozzle 1 from being cooled by the water-cooled mold 6. In order to reduce the conduction area, a slit 2 is provided on the outer surface of the nozzle as shown in the figure. It can be seen from the solid/liquid interface 3 that the molten metal is effectively cooled.

Mainly, the ingot obtained by the apparatus shown in Fig. 1 has fine (thin) columnar crystal grains as shown in the photograph 1 of Reference Fig. 1 (a) (L+). , it can be seen that grain boundary cracking is prevented.

Figure 2 shows the cooling rate distribution obtained from the dendrite arms basing (DAS), and shows that the cooling rate of the solidified shell forming part is improved.

Figure 3 shows a heater 9 in the slit area in Figure 1.
The heating temperature is 5° below the melting point of the metal to be cast.
It is appropriate to set the temperature to 10°C or more higher. That is, since the part of the refractory insulating brick nozzle 1 near the water-cooled mold 6 is at a high temperature, there is no solidification shell formation in this part, and since the molten metal is rapidly cooled in the water-cooled mold 6 at a rapid cooling rate, crystals do not form. The grains have become finer. This is also clear from the fact that the solid/liquid interface rises suddenly from the tip of the nozzle as shown in 3.

FIG. 4 shows that a part of the overhang part 12 of the nozzle 1 made of refractory and insulating bricks is provided with a polar brick 11 in order to supply lubricant, except for the lubricating sleeve shown in FIG. There is a slit 7) on the outer peripheral surface to reduce the insulation area with the water-cooled mold 6.

Then, the lubricant from the pumps P to I) reaches the water-cooled mold 6 from the lubricant reservoir 10 through the Polar brick 11, so that the molten metal is effectively cooled.

The fact that the solid/liquid interface also rises suddenly from the lubricant supplying Bolas brick 11 indicates that the cooling is large.

In FIG. 5, since the overhang part of the nozzle 1 made of fireproof and insulating bricks is often damaged, a slit is provided on the outer circumferential surface of the nozzle 1 to reduce the heat insulation area with the water-cooled mold 6, and the overhang part is often damaged. The hanging part is made of porous brick 11,
It is in contact with the water-cooled mold 6 via the lubricating sleeve 4, and pressurized gas from the gas source M is supplied from the porous brick 11 via the gas reservoir 13 to prevent contact between the molten metal and the nozzle 1. do. The gas pressure at this time is sufficient to resist the molten metal pressure in the tundish, and the lowest pressure is equivalent to the molten metal pressure. In this case as well, the cooling rate of the molten metal is high when viewed from the solid/liquid interface 3.

In FIG. 6, an electromagnetic pinch coil 14 is installed in a water-cooled mold 6, and a lubricant supply device 15 is connected to the tip of a nozzle 1 made of refractory heat-insulating brick with a slit provided on the outer periphery through a lubricating sleeve 4 to the water-cooled mold 6. It is set so that it is in contact with the It can be seen that the molten metal is rapidly cooled when viewed from the solid/liquid interface, and at the same time, since a flow is generated in the molten metal due to electromagnetic conduction, the crystal grains become extremely fine.

[Effect of the invention 1 As explained above, since the method for horizontal continuous casting of metal according to the present invention has the above configuration, the obtained ′gJy
L has fine crystal grains and is extremely excellent in that grain boundary cracks do not occur.

[Brief explanation of the drawing]

1 to 6 are diagrams for explaining the continuous metal casting method according to the present invention, and FIGS. 7 to 10 are diagrams for explaining the conventional horizontal continuous casting method for metal. 1. Fireproof insulation brick nozzle, 3. Solid/liquid interface, 4.
・Lubricating sleeve, 5. Ingot, 6. Water-cooled mold, 9.
Heater, 11...porous brick, 14...electromagnetic pinch coil. Fang 7 figure Tanfunzre λ Spear 8 figure Spear 9 figure

Claims (1)

[Claims] A horizontal continuous casting method for metals, characterized in that the molten metal supplied from a tundish is cooled to form a solidified shell in a water-cooled mold without forming a solidified shell in a feed nozzle.