JPH06134551A - Method and apparatus for producing metal ingot - Google Patents

Abstract

PURPOSE:To provide a method and an apparatus for producing a large scale metal ingot having remarkably fine crystal structure as a material having small anisotropy and excellent mechanical property, particularly toughness, even if the plastic working is executed. CONSTITUTION:Molten metal 5 is continuously poured into a narrow gap between a water cooling copper mold 6 without the bottom and a cylindrical stirring rod 3 having spiral groove set in the mold 6. The molten metal 5 is rapidly cooled, and the solidification is progressed and at the same time, a stirring rod 3 is vigorously and intensely stirred with a motor 1 through a coupling 2, and the solidified crystal grain is made to be fine to produce semi- solidified slurry 8. By accumulating this semi-solidified slurry 8 into a vessel 9 heated to the semi-solidified slurry temp. or lower, the large scale ingot composed of fine solidified structure is produced.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal ingot and an apparatus therefor. More specifically, the present invention produces a semi-solidified slurry in which extremely fine crystal grains are dispersed by rapidly stirring and vigorously stirring, and by accumulating the slurry without coarsening the crystal grains in the slurry. The present invention relates to a method and apparatus useful for producing a large-sized metal ingot having a fine crystal grain structure having small anisotropy and excellent mechanical properties, particularly toughness.

2. Description of the Related Art In a conventional large-sized metal ingot, the cooling rate is low because of its large heat capacity, and the crystal structure observed in the ingot after solidification is mainly well-developed coarse columnar crystals. . In the material produced by plastic working such as rolling from this ingot, the anisotropy is large,
Mechanical properties, especially toughness, are a problem. To prevent the formation of such well-developed coarse columnar crystal structure, grain refiner is added, alloying elements are added, low temperature casting is performed, or stirring is performed by various methods during solidification. Various methods have been proposed. Further, in the continuous casting method, a method of stirring the molten metal in the solidifying strand by electromagnetic force is adopted.
Among these conventional methods, the method of adding a grain refiner or an alloying element is not very desirable because the additive changes the original properties of the metal material. In the case of the low temperature casting method, troubles such as insufficient molten metal flow easily occur during casting. Even with the method of stirring during solidification, it is possible to obtain equiaxed crystals, but the size of the equiaxed crystals is large in proportion to the size of the ingot. This is because the secondary arm spacing of the crystalline dendrite is almost equal to the cooling rate.
This is an unavoidable phenomenon because it is inversely proportional to the 1/3 power.
Therefore, in order to form a metal ingot composed of a finely solidified structure, it is inevitable that quenching is performed, and for this purpose, as little molten metal as possible must be rapidly cooled. The production of large ingots is extremely difficult.

SUMMARY OF THE INVENTION The present invention solves the above drawbacks of the prior art and provides a method and apparatus for producing a metal ingot having a fine grain structure. In detail, it is possible to produce a large-sized metal ingot having a fine crystal grain structure, and to provide an excellent metal material having excellent mechanical properties and small anisotropy. Another object of the present invention is to provide a method for producing a metal ingot which can be used as a metal ingot used for a semi-melt processing method, which is promising in the future, and an apparatus therefor.

A method for refining the solidification structure of a metal ingot is to increase the number of crystal nuclei at the start of solidification and further prevent the generated crystal nuclei from growing large. It is to be. In order to increase the number of crystal nuclei in this way, it is important to increase the degree of supercooling during solidification to increase homogeneous and heterogeneous nucleation. In order to prevent large growth of crystal nuclei, the main means are to terminate solidification early by rapid cooling, and to prevent crystal growth by stirring. It is necessary to vigorously stir at the same time. The vigorous stirring not only prevents the formed crystals from growing large, but also prevents the formed crystals from coalescing and coarsening, and divides the formed crystals into new ones. It also has the effect of increasing the number of crystal nuclei as crystal nuclei and making them finer. Therefore, in the present invention, the molten metal is rapidly cooled by using a mold having a large cooling effect to increase the degree of supercooling during solidification and increase the generation of homogeneous and heterogeneous nuclei. Then, a stirring rod is inserted and arranged in the mold to reduce the gap between the inner wall of the mold and the outer surface of the stirring rod, and to pass a small amount of molten metal. Further, the mixture is rapidly cooled and vigorously vigorously stirred using a stir bar to prevent the produced crystals from coalescing and growing to become coarse, and to produce a semi-solidified metal slurry in which crystal grains are refined. In order to produce a large ingot, this quenching and stirring operation is continuously performed, and the rapidly solidified and solidified semi-solidified metal slurry containing a small amount of fine crystal grains is collected to produce a large ingot. At this time, the temperature and temperature of the container or continuous casting mold for accumulating the semi-solidified metal slurry such that fine crystal grains in the semi-solidified metal slurry are not coarsened and a sound metal ingot is obtained. Adjust the slope.

EXAMPLE First, an example of an apparatus for carrying out the method of the present invention is shown below. FIG. 1 is a cross-sectional view showing an outline of a rapid cooling stirring solidification apparatus for producing a batch-type metal ingot, which uses a cylindrical stirring rod having spiral grooves. A funnel 4 made of refractory heat-insulating brick for pouring molten metal 5 is installed on a bottomless water-cooled copper mold 6 water-cooled with water 7, and a bottomed bottom heated by a heater 10 under the water-cooled copper mold 6. The container 9 is installed. At the center of the funnel 4 and the water-cooled copper mold 6, a cylindrical stirring rod 3 with a spiral groove, which is connected to the motor 1 via a coupling 2, is arranged. In this apparatus, a molten metal 5 is stirred by a funnel 4 made of refractory heat-insulating bricks into a cylindrical water-cooled copper mold 6 having a bottom and a cylindrical groove with spiral grooves installed in a water-cooled copper mold rotated by a motor 1. A semi-solid metal slurry 8 is produced by casting in a gap with the rod 3, quenching with water 7, and vigorous agitation with a motor 1. Heat this slurry with a heater 1
A large-sized metal ingot is manufactured by accumulating in a bottomed container 9 heated to a temperature not higher than that of the semi-solidified metal slurry by 0. FIG. 2 is a cross-sectional view showing an outline of a rapid cooling stirring solidification apparatus for producing a continuous metal ingot using a plate-shaped stirring rod. Water 7
A funnel 4 made of refractory heat-insulating bricks for pouring the molten metal 5 is installed on a water-cooled bottomless water-cooled copper mold 6 which is connected to the bottom of the water-cooled copper mold 6 and fire-resistant heat-insulating materials 11 are vertically arranged. A container 9 for establishing a bottomless cross-sectional shape that is installed and heated by a heater 10 is installed. Further, a water-cooled copper cooler 12 cooled with water 7 is arranged below the container 9. A pinch roll 14 for continuously withdrawing the ingot after completion of solidification is arranged below these devices. In this apparatus, a molten metal 5 is mixed with a bottomless water-cooled copper mold 6 and a plate-shaped stirring rod 3 installed in a water-cooled copper mold rotated by a motor 1 by using a funnel 4 made of refractory heat insulating bricks. Cast in the gap of
The semi-solidified metal slurry 8 is produced by rapidly cooling and vigorously stirring at the same time. This slurry is heated by a heater 10
Is accumulated in a bottomless container 9 heated below the temperature of the semi-solidified metal slurry to determine the sectional shape, the solidification is completed by a water-cooled copper cooler 11, and the ingot after the solidification is completed by a pinch roll 14. Then, a large-sized metal ingot is continuously manufactured. This FIG. 1 of this invention
The following is an example of the method for producing a metal ingot by the above apparatus. Example 1 An Al-20 mass% Si hypereutectic alloy is melted to obtain a molten metal 5. Bottomless water-cooled copper mold with an inner diameter of 50 mm and a height of 100 mm 6
The molten metal 5 with a heating degree of 100 K is cast at a rate of 50 g / s into a gap between the cylindrical stir bar 3 made of graphite having an outer diameter of 40 mm and having a spiral groove installed in the mold 6, and 83.3 s
^It was stirred by a stirring rod 3 having a rotation speed of ^-1 (5,000 rpm).
The size of the primary Si crystal grains in the obtained semi-solidified metal slurry 8 is about 1/1 of that when cast into a water-cooled copper plate without stirring.
Miniaturized to 0. Also, diameter 50 mm heated to 200 ℃
By accumulating the semi-solidified metal slurry 8 in the graphite container 9 of 1., a sound ingot could be formed without growing fine crystals in the slurry. Example 2 A molten alloy 5 is obtained by melting an Al-12.6 mass% Si eutectic alloy. Bottomless water-cooled copper mold with an inner diameter of 50 mm and a height of 100 mm 6
The molten metal 5 having a heating degree of 100 K was cast at a rate of 50 g / s into a gap between the cylindrical stir bar 3 made of graphite and having an outer diameter of 40 mm and having a spiral groove installed in the mold 6, s
^It was stirred by a stirring rod 3 having a rotation speed of ^-1 (4,000 rpm).
The size of the eutectic Si crystal grains in the obtained semi-solidified metal slurry 8 grows into a thin plate shape when cast into a water-cooled copper plate without stirring, whereas it becomes a fine spherical shape. It was Further, by accumulating the semi-solidified metal slurry 8 in a graphite container 9 having a diameter of 50 mm heated to 200 ° C., a sound ingot could be produced without growing fine crystals in the slurry. . Example 3 An Al-20 mass% Si hypereutectic alloy is melted to obtain a molten alloy 5. Bottomless water-cooled copper mold 6 with inner diameter of 50 mm and height of 100 mm 6
The molten metal 5 with a heating degree of 100 K is cast at a rate of 50 g / s into the gap between the cylindrical stirring rod 3 made of graphite and having an outer diameter of 45 mm and having a spiral groove installed in the mold 6, s
^It was stirred by a stirring rod 3 having a rotation speed of ^-1 (2,000 rpm).
The size of the primary Si crystal grains in the obtained semi-solidified metal slurry 8 is about 1/5 of the size when cast into a water-cooled copper plate without stirring.
Was miniaturized.

INDUSTRIAL APPLICABILITY The present invention enables the production of a large-sized metal ingot having an extremely fine grain structure which cannot be produced by the conventional method. That is, by producing a large ingot composed of an extremely fine crystal grain structure, even when used as-cast or after plastic working, there is no component segregation, mechanical properties, especially toughness. It is possible to manufacture a metallic material which is excellent and has small anisotropy. Further, it is possible to provide a low-cost product by omitting steps, and to provide a metal ingot which can be used in the semi-melt processing method.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a quenching stirring solidification apparatus for producing a batch type metal ingot using a stirring rod having a spiral groove.

FIG. 2 is a schematic sectional view of a rapid cooling stirring solidification apparatus for producing a continuous metal ingot using a plate-shaped stirring rod.

[Explanation of symbols]

 1. Motor 2. Coupling 3. Stir bar 4. Fireproof insulation brick funnel 5. Molten metal 6. Bottomless water-cooled copper mold 7. Water 8. Semi-solid metal slurry 9. Heated container 10. Heater for container heating and holding 11. Fireproof heat insulating material 12. Water-cooled copper cooler 13. Large metal ingot 14. Pinch roll

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[Procedure amendment]

[Submission date] September 29, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

Claims (6)

[Claims] 1. Molten metal is continuously poured into a narrow gap between a bottomless mold and a stirring rod installed in the mold, and the molten metal is rapidly cooled to cause solidification and stirring at the same time. A metal consisting of a fine solidified structure characterized by stirring with a rod, refining the solidifying crystal grains to produce a semi-solidified slurry, and accumulating this semi-solidified slurry in a container heated to a temperature below the temperature of the semi-solidified slurry. Manufacturing method of ingot. 2. Molten metal is continuously poured into a narrow gap between a bottomless mold and a stirring rod installed in the mold, and the molten metal is rapidly cooled to cause solidification and stirring at the same time. Stir with a rod to atomize the solidified crystal grains to produce a semi-solidified slurry, pass this semi-solidified slurry through a container for heat molding to determine the cross-sectional shape, and continuously withdraw it while completing solidification in the cooler below. A method for producing a metal ingot having a fine solidified structure characterized by the above. 3. A funnel made of refractory insulation brick for pouring molten metal is placed on a bottomless mold, and the funnel made of refractory insulation brick and the motor above the center of the mold are coupled via a coupling to an upper motor. An apparatus for producing a metal ingot having a fine solidification structure, in which a rotating stirring rod is inserted and a bottomed container heated by a heater is disposed under a mold. 4. A funnel made of refractory heat-insulating brick for pouring molten metal is placed on a bottomless mold, and the funnel made of refractory heat-insulating brick and the motor above the center of the mold are coupled via a coupling. A rotating stirring rod is inserted and arranged, and a bottomless container for determining the cross-sectional shape is arranged by connecting the lower part of the mold with the refractory heat insulating material connected to the upper and lower parts and by heating with a heater. A metal consisting of a fine solidified structure characterized by connecting a cooler under the bottom container and arranging a pinch roll for continuously drawing out the ingot which has completed solidification under these devices. Ingot manufacturing equipment. 5. The apparatus according to claim 3, wherein the stirring rod is a cylindrical stirring rod having a spiral groove. 6. The apparatus according to claim 3, wherein the stirring rod is a plate-shaped stirring rod.