JPS61245949A - Continuous casting method - Google Patents

Abstract

PURPOSE:To eliminate the various factors to influence adversely the quality of an ingot by casting the ingot while maintaining the temp. of a molten metal in contact with the inside wall surface of a casting mold in a meniscus position at the solidification point of the molten metal or above. CONSTITUTION:The molten metal 7 is admitted from a tundish 4 via an immersion nozzle 6 into the casting mold 2. The molten metal 7 admitted into the mold is maintained at the temp. of the solidification point of the metal 7 or above by a heat-generating inductor 10 in the upper part 9 of the casting mold in the meniscus part of the molten metal so that a thoroughly molten layer 15 is formed. The molten layer is then cooled to solidify by pipings 14 for cooling water in the lower part 13 of the casting mold to have the substantial solidification thickness and thereafter the ingot is cooled further in a cooling spray zone 8 and is drawn by pinch rolls. The ingot which has no oscillation marks and does not contain non-metallic inclusions, etc. right under the surface skin of the ingot is obtd.

Description

[Detailed Description of the Invention] (Industrial Application Field) Kinoe F14 is related to the continuous casting method, especially for various factors that adversely affect the quality of slabs such as oscillation marks, non-uniform solidification, and non-metallic inclusions. The present invention relates to a continuous casting method that can remove .

(Prior Art) Molds used in conventional continuous casting have mainly been those in which a cooling water flow path is provided on the back side of a copper plate, and the molten metal side is plated or the like.

When this type of casting amount is used, as shown in FIG. 3, the heat of the molten metal is removed by the cooling water through the copper plate, so that a solidified shell 1 is formed from the meniscus of the molten metal. In addition, in the figure, 2 is a mold, and 3 is a molten slag layer.

In addition, in order to suppress the growth of the solidified shell in the meniscus area and improve the quality of the slab, we applied insulation to the part of the casting corresponding to the meniscus area, and also created mechanical or chemical irregularities. Although there are molds that have been used, these are slow cooling methods that weaken the heat removal from the meniscus of the mold, and do not actively suppress solidification in the meniscus.

(Problems to be Solved by the Invention) In continuous casting using the conventional mold described above, the amount of heat removed from the mold at the meniscus portion is large.
A solidified shell grows on the upper surface of the meniscus. This solidified shell is then deformed by the oscillation, forming oscillation marks and promoting non-uniform solidification (see Figure 4).

On the other hand, if the solidified shell of the meniscus grows straight above the meniscus, non-metallic inclusions, air bubbles, etc. will remain inside the solidified shell, causing a significant deterioration of the quality of the slab just below the skin. (See Figure 5).

In addition, Figure 4,! In Figure 5, @ indicates the slag solidification area.

The present invention has been made to solve the above problems.

(Means for Solving the Problems) The gist of the present invention is to perform casting while maintaining the temperature of the molten metal in contact with the inner wall surface of the mold at the meniscus position to be equal to or higher than the freezing point of the molten metal.

(Function) In the method of the present invention, since the initial solidification position is below the meniscus, the slab produced has no oscillation marks and may contain non-metallic inclusions and air bubbles directly under the skin. 4) A slab with good surface quality is obtained.

(Example) The present invention will be described in detail below based on an example shown in FIG. Note that the same numbers in the drawings as in FIGS. 3 to 5 indicate the same or corresponding parts, and detailed description thereof will be omitted.

In the figure, 4 is a tanditshu, 5 is a sliding nozzle,
6 is an immersion nozzle, through which the molten metal 7 is poured into the mold 2.
The solidified shell 1 is gradually grown through primary cooling by the mold 2 and secondary cooling by the cooling spray zone 8, and is continuously cast.

By the way, in the method of the present invention, in order to perform casting while maintaining the temperature of the molten metal 7 in contact with the inner wall surface of the mold at the meniscus position above the freezing point of the molten metal 7, the upper part of the mold 2 (main i
(x'=')y space part) and the structure of the lower part are changed.

That is, the mold upper part 9 is made of a refractory material or a corrosion-resistant metal, and a heating element 10 such as a heating element or a high-frequency induction coil is provided therein. prevent it from becoming 9
Ru. Among them, reference numeral 12 denotes a temperature measuring element located at the meniscus portion of the molten metal 7 and the inner peripheral side of the mold upper part 9, respectively, in order to control the calorific value of the heat generating derivative 10.

9. The lower part 13 of the mold is a water-cooled mold made of high heat conductive metal (C steel, etc.) similar to conventional molds. Note 14
is the cooling water piping.

According to the method of the present invention, the molten metal 7 flowing into the mold 2 from the tundish 4 through the immersion nozzle 6 is deposited in the meniscus portion of the casting porcelain upper part 90 and the exothermic inductor 10.
A completely molten layer 15 is formed without solidifying, and after being cooled and solidified by the mold lower part 13 below and having a sufficient solidified thickness, it is further cooled by the cooling spray zone 8 and pulled out by pinch rolls. As a result, a slab is obtained that has no oscillation marks and does not contain non-metallic inclusions directly under the surface of the slab.

Note that although this example shows the case of downward pulling,
Needless to say, it is also applicable to horizontal drawing.

(Effects of the Invention) As described above, the method of the present invention suppresses the generation of solidified shells due to rapid cooling in the meniscus part during casting. It is possible to obtain a slab with good surface properties, which prevents molding and does not contain non-metallic inclusions directly under the skin of the slab.

[Brief explanation of drawings]

Figure 1 is a drawing explaining the solidification state of the molten metal in the meniscus area in case the method of the present invention is used, Figure 2 is an example of the method of the present invention, and Figures 3 to 5 are diagrams using the conventional method. 1 is a solidified shell, 2 is a mold, 7 is a molten metal, 9 is an upper part of a mold, 10
is an exothermic derivative, 13i! Lower part of the mold. Patent applicant: Sumitomo Metal Industries, Ltd. Figure 1 Figure 3

Claims (1)

[Claims] (1) A continuous casting method characterized by casting while maintaining the temperature of the molten metal in contact with the inner wall surface of the mold at the meniscus position above the freezing point of the molten metal.