JPH01215446A - Continuous casting method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a continuous casting method.

The molten steel tapped from the melting furnace is received in a ladle, the molten steel with refined slag floated and separated in the ladle is then received in a tundish, and the molten steel with non-metallic inclusions floated and separated in the tundish is supplied to the mold. , a predetermined slab is continuously cast in the mold.

The present invention relates to improvements in continuous casting as described above.

<Conventional technology and its problems> By the way, in continuous casting of molten metal, at the end of continuous casting, new high-temperature molten metal is not supplied into the mold, so the surface layer of the metal in the mold becomes excessively large. The temperature decreases, and as a result, shrinkage pores occur at the end of the continuously cast slab.

The occurrence of such shrinkage holes at the end of a slab is unavoidable, and the end where shrinkage holes have occurred is unsuitable for use as a product, so it is cut off. If no measures are taken, such as
The depth of the shrinkage holes that occur is unexpectedly long, and there is a problem in that the yield decreases significantly due to cutting off the end portion where the shrinkage holes have occurred.

<Problems to be Solved by the Invention and Means for Solving the Problems> The present invention provides an improved continuous casting method that solves the conventional problems as described above.

Therefore, the present invention provides the following advantages when continuously casting molten metal by supplying it into a mold:
The present invention relates to a continuous casting method characterized in that a heating agent is added to the metal surface in the mold at the end of continuous casting, and the metal surface is coated with the heating agent.

An important point in the present invention is that by coating the metal surface inside the mold with a heat generating agent at the end of continuous casting, an excessive drop in temperature of the metal surface layer inside the mold is prevented, resulting in shrinkage pores. By shortening the depth of the pores, it is possible to reduce the yield loss caused by cutting off the ends where shrinkage holes have occurred.

The configuration of the present invention will be explained in more detail below based on one drawing.

<Example> FIG. 1 is an overall schematic diagram showing in cross section one implementation procedure of the present invention,
FIG. 2 is a partially enlarged cross-sectional view showing the final stage of continuous casting in the procedure.

The ladle 11 and the tundish 21 are connected to each other by a long nozzle 12 provided on the bottom of the ladle 11, and the tundish 21 and a mold (for example, a water-cooled Cu mold) 31 are connected to the bottom of the tundish 21. The mold 31 is associated with a submerged nozzle 22 .
A plurality of rolls 32 are arranged downstream of. The immersion nozzle 22 is generally made of Al203-C or Zr02-C.
A refractory nozzle made from a commercially available refractory is used, and in the case of the drawing, it is a two-hole nozzle, but depending on the type of slab, for example, a four-hole nozzle or a straight nozzle may be used as appropriate.

In Fig. 1, which shows the flow state of molten steel in the middle stage of continuous casting (regular continuous casting period), molten steel tapped from a melting furnace (not shown) floats and separates refined slag B in a ladle 11, and then flows into a long Tundish 2 through nozzle 12
1, and then the non-metallic inclusions are floated up in the tundish 21, adsorbed and separated by the synthetic flux C, and then supplied to the mold 31 through the immersion nozzle 22, where it is continuously cast into a predetermined slab. There is.

During this steady continuous casting period, high-temperature molten steel A is continuously supplied from the immersion nozzle 22 into the mold 31, while in the center of the mold 31 there is still a portion of molten metal in an inverted triangular shape. A solid solidified metal portion E is continuously formed in the outer peripheral region of the molten metal portion, that is, in the inner peripheral region of the mold 31. And the above mold 31
The temperature of the metal surface layer inside the tube does not drop excessively due to the high temperature molten steel A newly continuously supplied from the immersion nozzle 22.

In the present invention, a heat generating agent is added to the metal surface within the mold 31 at the end of the continuous casting after the steady continuous casting as described above is performed, and the metal surface is coated with the heat generating agent.

In FIG. 2 showing the state inside the mold at the end of continuous casting, a heat generating agent 41 is added to the metal surface within the mold 31, and the metal surface is coated with the heat generating agent 41. In this case, the exothermic agent 41 is a so-called exothermic powder containing an oxidizing agent such as KMnOa, for example (CaO-Si02-
(Ca-Si)-KMnOa-Fe203), etc., and causes an exothermic reaction by an oxidizing agent.

As described above, when the metal surface inside the mold 31 is coated with the heat generating agent 41 at the end of continuous casting, the heat generating agent 41 has a heat insulating effect, and an excessive drop in temperature of the metal surface layer inside the mold 31 can be prevented. This makes it possible to shorten the depth of the shrinkage hole that occurs in response to the molten metal portion, which ultimately shortens the depth of the end portion F that is cut off due to the generation of the shrinkage hole. This is possible.

If no conventional measures are taken at the end of continuous casting, the temperature of the surface layer of the metal inside the mold will drop significantly, and the end portion, which has a long depth corresponding to the molten metal portion, will eventually have to be cut off. Put it away.

Although it depends on the continuous casting conditions such as the type of molten steel and slab, according to the present invention, the cutoff length at the end can be shortened to about 30% of the conventional length, and the decrease in yield can be reduced accordingly. can.

<Effects of the Invention> As explained above, the present invention has the following advantages: By coating the metal surface in the mold with a heat-generating agent at the end of continuous casting, the depth of shrinkage holes that result as a result of This has the effect of making it possible to reduce the decrease in yield due to cutting off the end portion where the shrinkage hole has occurred.

[Brief explanation of the drawing]

FIG. 1 is an overall schematic cross-sectional view showing one implementation procedure of the present invention;
FIG. 2 is a partially enlarged cross-sectional view showing the final stage of continuous casting in the procedure. 11.-take fi, 12. Long fist nozzle 21..Tandishu, 22III + immersion nozzle 31..Mold,
32... Roll 4111 - Exothermic agent A... Molten steel B... Refined slag C... Synthetic flux D... Molten metal part E... Solidified metal part Patent applicant Daido Steel Co., Ltd. Agent Patent attorney Iriyama Hiromasa

Claims (1)

[Claims] 1. Continuous casting characterized by adding a heat generating agent to the metal surface in the mold at the end of the continuous casting to coat the metal surface with the heat generating agent when molten metal is supplied into the mold and continuously cast. Method.