JPS59223140A - Production of aluminum ingot - Google Patents

Abstract

PURPOSE:To decrease the amt. of the surface to be machined and to improve the yield of a product by casting continuously aluminum (alloy) in such a way that the content of boron and a cooling rate maintains a specific relation. CONSTITUTION:Aluminum or an aluminum alloy contg. boron is melted. The molten aluminum or aluminum alloy is then continuously cast at the above-mentioned relation between the content B (ppm) of boron and a cooling rate R ( deg.C/sec) which is so controlled as to be maintained within the range enclosed by the straight lines connecting the points a(B=3, R=2.7), b(B=25, R=1.8), c (B= 25, R=5), d(B=3, R=11) shown in the figure. The formation of the fir wood like structure in the casting ingot is obviated by the above-mentioned method, by which the amt. of the surface to be machined is reduced and the yeild of the product is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to casting conditions for aluminum alloys for rolling, and in particular, the cooling rate when casting aluminum alloys for rolling that crystallize Δ1-Fe-based intermetallic compounds inside the ingot. This is a method of controlling the main structure of fir that forms inside the ingot by controlling the

Aluminum or its alloys, such as J181000 series or 5000 series aluminum alloys, are Al-
It is an alloy that crystallizes Fe-based intermetallic compounds, and often forms a fir-like structure inside the ingot.

To explain this with reference to drawings, Fig. 1 is a schematic diagram of manufacturing an ingot by continuous casting, in which a molten metal M is poured into a mold 1 in which cooling water is circulated, is drawn out downward while solidifying, and then is poured into a nozzle. The ingot S is cooled by the spray 3 of cooling water injected from the ingot S.

As shown in FIG. 2, the cross section of this ingot has an internal area A indicated by diagonal lines, which appears in the shape of a fir tree, and an external area B outside which appears.

In the internal region A of this fir's main structure, △16-Fe is crystallized, and in the external region B, A13-Fe crystal or △lm-
Fe crystals are crystallized. By the way, when the internal region A and the external region B of the main structure of this fir are subjected to etching treatment with caustic soda or anodizing treatment, the effect received by these treatments is different, so for example, the internal region Δ
The outer region 31B becomes black or dark gray, while the outer region 31B becomes a relatively light gray, so that the different tissues can be clearly distinguished. Therefore, when line C in Fig. 2 becomes a facing surface due to the surface side of the ingot surface that is normally performed, both the inner region 1*A and the outer region 1ii1iB will appear on the surface of the processed material. As a result, a striped pattern appears due to the surface treatment, and the product has to be scrapped due to poor appearance.Even if it is remelted, oxidation loss is large, resulting in a considerable drop in product yield.

Many studies have been carried out on the cause of the vertical wood-framed edges, and it is believed that this is because Δ1-Fe-based intermetallic compounds with different electrochemical properties crystallize differently depending on the location.

This Al-Fe based intermetallic compound includes Al 3Fe,
It is known that At6Fe and Al11Fe exist, which have a close relationship with the cooling rate. for example,
A1mFe, Al6Fe in descending order of cooling rate
, Al 3 Fe crystallizes.

In the currently employed continuous casting method for aluminum or aluminum alloy, the cooling acceleration is within the range of the cooling rate at which the above three types of intermetallic compounds crystallize.

Conventionally, alloy components such as nickel, cobalt, vanadium, and calcium are added to make the fir's main outer navy weave thicker, so that the entire surface becomes the outer texture IB even when the face side or rolling is performed. That has been tried.

The present invention, in contrast to the prior art described above, provides a solution to the internal region 1ii! by adjusting the cooling rate of the ingot in relation to its boron content. This method aims to prevent defects caused by vertical woodwork edges by expanding A toward the casting surface.

The structure of the present invention is such that when aluminum or aluminum alloy containing boron is continuously cast, the relationship between the boron content and the cooling rate is at point a (B=3
．． R= 2.7), b (B= 25.R= 1
．． 8>, c (B=25.R=5.0), d
(B=3.R=11) This is a method for manufacturing an aluminum ingot, characterized by controlling the aluminum ingot so that it lies within a region surrounded by a straight line connecting (B=3.R=11).

Detailed explanation with reference to the drawings. Figure 3 shows the appearance of fir wood edges when aluminum alloys containing various amounts of boron are cast and cooled at various cooling rates. As a result of research on the relationship between boron content and cooling rate, when the relationship between boron content and cooling rate is within the above range,
This is a graph showing a region where the crystallization region of Fe crystals sufficiently expands within 5 mm from the casting surface, and the circle mark indicates that AI 6Fe crystals have crystallized. Boron content is 3 rllll
Below lll, when the cooling rate is slow, the external region where Al3-Fe crystals crystallize expands, and when the cooling rate is fast, the
The outer region where +mFe crystals crystallize becomes dominant.

Further, in the region below straight lines a and b, the outer region where A1aFe crystals crystallize expands, and in the region above straight lines d and c, the outer region of A1mFe crystal becomes predominant. A region where the boron content exceeds 25 ppm has not been studied from a practical standpoint.

The boron content can be satisfied, for example, by adding a wire-like titanium-boron alloy added as a grain refiner, but when the cooling rate is slow, the amount of wire-like alloy added from the trough to the slag may be lower than usual. should be excessive.

The cooling rate is controlled by the casting rate, nozzle 2 in Figure 1.
It is controlled by changing the amount of cooling water ejected from the cooling water and the position of the secondary cooling zone.

Each of the 3i
Cross section 2 of an alloy (JISlloo) consisting of 0.05-0.2% Fe, 0.05-1.0% Fe, and other impurities.
These are the results of a continuous casting test on 50ml x 500111111. In addition, the cooling rate of the ingot is 7% from the casting surface.
It shows a representative value of temperature change at a position of 0 to 90 mm.

6- Example 1 Casting speed 100mm/min Cooling water M
i1. OJ2/min -cm cooling rate
3.2℃/sec boron content
6 ppm The main structure of fir did not appear in the ingot produced under the above conditions.

Example 2 Casting speed 50mm/min cooling water @0
．． 7° C./n+in-cm Cooling rate: 2.7° C./sec Boron content: 12 ppm In this case as well, no fir structure appeared in the ingot.

Comparative Example An ingot was cast under the same conditions as in Example 2 except that only the B value was set to 6 ppm.

As a result, the main organization of fir appeared.

Example 3 Casting speed 50mm/min Cooling water amount 0
．． 71/min-cm cooling rate 2
．． 5°C/SeG boron content 8 ppm (initial 4 times) In order to enter the range of this invention shown in the attached drawing, titanium- The amount of boron alloy wire added was increased.

In this example, the main tissue of fir did not appear.

As shown above, according to the present invention, in addition to being able to expect a reduction in the amount of surface cutting and a reduction in the number of cut areas at the bottom of the ingot,
If the titanium-boron alloy wire is added as a crystal refiner, unlike the prior art described above, no special additive components are required to control the vertical main structure.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a continuous casting apparatus, Fig. 2 is a drawing showing the cross section of an ingot manufactured by continuous casting and the vertical structure appearing therein, and Fig. 3 is a diagram showing the boron content of the ingot of the present invention. Graph showing the relationship between cooling rates. In the figure, 1 is the mold, 2 is the water spray nozzle, 3 is the spray, M is the molten metal, S is the ingot, A is the internal area of the fir book structure, and B is the external area. , C is the amount of surface cutting. Patent Applicant Sumitomo Light Metal Co., Ltd. Agent Patent Attorney Hide Komatsu Agent Patent Attorney Hiroshi Asahi 9- Procedure: ? + City official letter (spontaneous) September 5, 1980 1, Incident indication Patent application No. 1982-097927 2
, Title of invention Method for manufacturing aluminum ingot 3,
Relationship with the case of the person making the amendment Patent application Name of person
(227) Sumitomo Light Metal Industries, Ltd. (1) Page 2 No. 5
Delete the line "Figure 1 is". (2) Added “manufactured aluminum” after “by construction” in line 6 of the same. (3) Lines 6 to 11 of the same ``manufacture...this ingot''
Delete. (4) Corrected “Figure 2” in line 11 to “Figure 1.” (5) Lines 14-15 rAl 6-Fe J of “Al
Corrected to 6Fe J. (6) Lines 15 and 16 of the same “Al3-Fe crystal” are rAl
Corrected to 3 Fe J. (7) rAlm the 16th line “All1-Fe crystal”
Corrected to FeJ. (8) Page 3, line 5, “Figure 2” was corrected to “Figure 1.” (9) The last line of page 4, “Figure 3” was corrected to “Figure 1, Figure 2.” (10) Page 5, line 5, “Figure 3” was corrected to “Figure 2.” (11) Delete “crystal” in line 11. (12) Corrected to fi first bamboo FeJ. (13) Delete “crystal” in line 17. (14) Delete “crystal” at the end of the same line. (15) Delete "Crystal" in the 1st and 2nd lines of page 6. (16) Delete “Figure 1 is a schematic diagram” at the end of page 8. (17) Page 9, line 1, “Figure 2” was corrected to “Figure 1.” (18) "3rd" in the 4th line was corrected to "Figure 2". (19) Delete lines 6-7 of the same statement, “1 is the mold...S is the ingot.” (20) Box 1 in the drawing was deleted as shown in the attached sheet. (21) The same “Figure 2” has been revised to “Figure 1” as shown in the attached sheet. (22) "Figure 3" has been amended to "Figure 2" as shown in the attached sheet. 3- (%lj paper): JP-A-59-223140 (6) Figure d (B:3.R:11) 1 ( ), 02013040 Boron serving amount: B (99m)

Claims (1)

[Claims] When continuously casting aluminum or aluminum alloy containing boron, what is the relationship between the boron content and cooling rate? Point a shown in diagram A3 (B=3.R-2,7)
,b (B=25.R=1.8),O(B=2
5. A method for manufacturing an aluminum ingot, characterized in that control is performed so that R = 5.0>, (1 (B-3, R = 11)).