Method and plant for the production of long ingots having a large cross-section

Abstract

Method for producing ingots made of metal having cross-sectional areas of at least 0.10 m.sup.2 of a round, square or rectangular shape through casting of metal or molten steel either directly from the casting ladle (1) or using a fireproof lined intermediate vessel (3) in a short, water-cooled ingot mold open downwards (4) and withdrawing of the solidified ingot (6) from the same downwardly movable withdrawing tool (8), wherein the casting process is continued with a casting rate determined in accordance with the casting cross-section for as long as the desired or maximum ingot length determined by the height of lift of the withdrawing tool (8) is reached, and additional liquid metal is fed at the end of the regular casting process to an extent that at least the contraction of the metal and steel melt occurring during solidification is balanced during, and whereby after completion of the regular casting process and completion of the ingot withdrawal, the casting process is continued with a casting rate reduced by at least the Factor 10 from the heatable casting ladle (1) or the heatable intermediate vessel (3) or a distribution container, and is reduced progressively or continuously at the end of the solidification to 10% the rate at the start of the additional casting.

Claims

1. Method for producing ingots made of metal having cross-sectional areas of at least 0.10 m.sup.2 of a round, square or rectangular shape through casting of metal or molten steel either directly from a casting ladle (1) or using a fireproof lined intermediate vessel (3) in a short, water-cooled ingot mold open downwards (4) and withdrawing of solidified ingot (6) from the same downwardly movable withdrawing tool (8), wherein the casting process is continued with a casting rate determined in accordance with the casting cross-section for as long as the desired or maximum ingot length determined by the height of lift of the withdrawing tool (8) is reached, and additional liquid metal is fed at the end of the regular casting process to an extent that at least the contraction of the metal and steel melt occurring during solidification is balanced during, and whereby after completion of the regular casting process and completion of the ingot withdrawal, the casting process is continued with a casting rate reduced by at least the Factor 10 from the heatable casting ladle (1) or the heatable intermediate vessel (3) or a distribution container, and is reduced progressively or continuously at the end of the solidification to 10% the rate at the start of the additional casting.

2. Method according to claim 1, wherein the ingot (6) withdrawn from the ingot mold (4) is guided during the casting process through a secondary cooling zone (12), where it can be cooled through spray water, spray mist or compressed air, and wherein this cooling is progressively or continuously reduced during the remaining solidification phase after the end of the casting process and completion of the ingot withdrawal.

3. Method according to claim 2, wherein the quantity melted during the solidification corresponds to 2-10% of the total weight of the ingot (6).

4. Method according to claim 1, wherein after completion of the regular casting process and completion of the ingot withdrawal, the casting process is continued with, at the most, the regular casting speed, so that the level of the metal in the ingot mold (4) rises up to the upper edge of the ingot mold until an additional height of max. 10% of the ingot length is reached in an insulated top piece (22) lined by ceramic mounted on the ingot mold (4).

5. Method according to claim 4, wherein the insulated top unit (22) lined by ceramic is additionally heated.

6. Method according to claim 1, wherein the ingots are made of steel.

7. Method according to claim 1, wherein the ingots are of a round shape.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A detailed description of embodiments of the invention follows, with referenced to the attached drawings, wherein:

(2) FIG. 1 shows an electroslag heating system in a waiting position;

(3) FIG. 2 shows a plant in accordance with the present invention;

(4) FIG. 3 shows a plant in accordance with the invention;

(5) FIG. 4 shows a plant according to the invention; and

(6) FIG. 5 shows an ingot mold part of a plant according to the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(7) FIG. 1 shows a schematic representation of a plant suitable for the implementation of the method according to the invention during the regular casting process. The liquid metal 2, preferably liquid steel, contained in a lined casting ladle 1 arrives across a likewise lined intermediate vessel 3 at the short, water-cooled, oscillating ingot mold 4, which may be provided with an ingot mold stirrer 10 in the liquid metal pool 5, which is enclosed by the solidified slab shells of the casting ingot 6 being formed.

(8) The metal level in the ingot mold 4 is generally covered through casting powder 7. It is also possible to perform the metal feeding to the ingot mold 4 directly from the casting ladle 1, and to be dispensed with the intermediate vessel 3. The liquid metal 2 is lead through so-called ceramic shrouds 24 for protection against oxidation.

(9) The ingot 6 being formed, which is resting on a bottom plate 8 with the withdrawing mechanism 9, is detached downwards according to the casting speed until the desired or max. possible ingot length based on the plant design is reached.

(10) In addition to the optionally provided electromagnetic ingot mold stirrer 10, an electromagnetic stirrer 11 can also be applied below the ingot mold 4 in the area of the secondary cooling zone 12.

(11) Furthermore, an electromagnetic stirrer 13 movable in the vertical direction can be moved downwards with the bottom plate 8 during the casting process and can be moved upwards after completion of the lowering process with proceeding solidification along the ingot 6.

(12) In FIG. 1, an electroslag heating system is shown in waiting position, which can be moved into the melting or casting position after completion of the casting process. The plant consists of a moving device 14, which can also be designed as pivoting device. Said device bears a mast 15 along which an electrode carriage 16 is arranged in a movable way, which in turn bears a consumable electrode 18 in an electrode support arm 17. Instead of a consumable electrode, a non-consumable graphite electrode can also be applied. The system is connected to an AC or DC source 19 via the heavy current busbar 17 shown in FIG. 2 and the flexible high current cable 25.

(13) FIG. 2 shows a plant in accordance to the invention, in which, on the one hand, the ingot 6 is heated by melting a consumable electrode 18 after completion of the regular casting process following the electroslag remelting process after application of a metallically active slag bath 20, and, on the other hand, the liquid material is fed in the molten liquid pool 5.

(14) FIG. 3 shows a plant according to the invention with an intermediate vessel 3, which can be heated for example using built-in induction coil 21.

(15) FIG. 4 shows a plant according to the invention with an intermediate vessel 3, which is heated following the electroslag heating process after application of a metallically active slag bath 27 through electrodes 28, which are electrically powered by a power source 26.

(16) FIG. 5 shows the ingot mold part of a plant according to the invention, on which a ceramic insulating top piece 22 is mounted which has been filled with a liquid melt, which can be kept warm, for example, through inductive heating 23, through continuing the casting process after achieving the provided ingot length and completion of the ingot withdrawal.