JPS63123550A - Continuous cast block for berylium-copper alloy and its continuous casting method - Google Patents

Abstract

PURPOSE:To continuously cast a cast block of berylium-copper alloy having excellent cold workability by making a thickness of inverse segregation layer at outer circumferential part of the cast block the specific value or lower and the ratio of unidirectional solidified structure extending parallel to the cast block drawing direction to the whole cast block, the specific value or more. CONSTITUTION:The desirable continuously cant block of the berylium-copper alloy has 0-0.05 mm thickness of inverse segregation layer at the outer circumferential part of the cast block and >=80% unidirectional solidified structure extending parallel to the cast block drawing direction to with respect the whole cast block. At the time of casting, while the molten berylium-copper alloy in the holding furnace 1 is continuously drawn by pinch rolls 3 from a mold 2 holding to the temp. condition of inner wall thereof, which the molten metal is not solidified, the cast block 20 is rapidly cooled by cooling water nozzle 4 at the outlet of mold 2. Thus, while forming the temp. gradient as parallel to the drawing direction in the inner part of cast block 20, the unidirectional solidification is executed near the outlet of mold 2. In this way, the continuously cast block of berylium-copper alloy having excellent cold workability is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a continuous ingot of beryllium copper alloy and a continuous casting method thereof.

(Prior art) Beryllium copper alloy is often processed into a plate material of about 0.1 to 1.0 fl and used as a conductive spring material.
To manufacture it, first, an ingot with a large cross-sectional area is produced by a semi-continuous casting method called DC casting using a water-cooled copper mold, and after the thick reverse segregation layer on the surface is removed, it is hot worked. This required the process of making a plate with a small cross-sectional area, and then repeating cold working and annealing to make a thin spring material. This complicated process is necessary because, first, beryllium-copper alloys exhibit severe reverse segregation behavior, and the reverse segregation layer that is formed when molten metal containing impurities is extruded to the surface during solidification is extremely thick. For this reason, it is necessary to remove the reverse segregation layer by scraping off the surface of the ingot thickly, which has the disadvantage of lowering the yield. In addition, the ingot solidified by cooling from the inner wall surface in a water-cooled copper mold contains many columnar crystals extending perpendicularly to the wall surface, which significantly reduces the plastic workability of the ingot. In addition to requiring complicated steps, cracks may still occur at the grain boundaries of columnar crystals during rolling.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems and has excellent cold workability despite being made of a beryllium-copper alloy with severe reverse segregation behavior. This was completed with the aim of creating a continuous ingot of beryllium copper alloy that has a uniform m-weave throughout, and a continuous casting method for the same.

(Means for solving the problems) The present invention is characterized in that the thickness of the reverse segregation layer on the outer periphery of the ingot is 0 to 0°050.
A first invention relating to a continuous ingot of beryllium copper alloy which is directly water-cooled, and in which 80% or more of the entire ingot has a unidirectional solidification structure extending parallel to the ingot drawing direction, and a molten metal of beryllium copper alloy. The ingot is continuously pulled out of a mold whose inner wall surface is maintained at a temperature that does not solidify the molten metal, and is rapidly cooled at the mold outlet, thereby creating a temperature gradient inside the ingot parallel to the direction of withdrawal. This invention consists of a second invention relating to a continuous casting method for beryllium copper alloy in which unidirectional solidification is performed near the outlet and direct water cooling is performed.

Reverse segregation occurs when an alloy with a wide solidification range between the liquidus and solidus solidifies, and the internal liquid, which has a low melting temperature and contains many impurities, passes through the gaps in the external crystals that have already solidified and shrunk. This is a phenomenon in which the beryllium-copper alloy is extruded to the outer periphery and solidified, and because the beryllium copper alloy has a wide solidification temperature range and a high shrinkage rate, it exhibits particularly remarkable reverse segregation behavior among many alloys. When an ingot is semi-continuously cast by the conventional method, the thickness of the reverse segregation layer at the surface layer is 1 to 3.
By adopting the continuous casting method of the second invention, the continuous ingot of the beryllium-copper alloy of the first invention of the present application is formed such that more than 80% of the entire ingot is cast in one direction extending parallel to the ingot drawing direction. In this case, solidification progresses simultaneously inside the section perpendicular to the wall surface of the ingot, and there is no solidification time difference between the surface layer and the inside, so the surface layer of the ingot is reversed. The thickness of the segregation layer is 0 to 0.05 tm. As a result, unlike the conventional ingot of beryllium copper alloy, the continuous ingot of the first invention of the present application does not require thickly scraping off the surface layer, and the product yield can be significantly improved.

In addition, when 80% or more of the entire ingot has a unidirectional solidification structure extending parallel to the ingot drawing direction, it not only does not contain columnar crystals perpendicular to the wall surface, but also contains only one metal crystal. Since the length in the direction is several meters or several tens of meters or more, which is virtually infinite, there is almost no risk of cracking caused by grain boundaries during processing, and it has extremely excellent cold workability. becomes.

The second invention of the present application relates to a continuous casting method for obtaining a continuous ingot of beryllium copper alloy as described above, and as shown in FIG. A mold (2) whose inner wall surface is maintained at a temperature that does not solidify the molten beryllium copper alloy is installed, and the continuous ingot (20) is continuously pulled out by pinch rolls (3) while the mold (2) is heated. Cooling water is directly injected from the cooling water nozzles (4) and (5) above and below the continuous ingot (20) at the outlet of the continuous ingot to cool the ingot, forming a temperature gradient inside the ingot parallel to the drawing direction. Solidification is performed near the exit of mold (2). At this time, the withdrawal speed and cooling rate are appropriately controlled to keep the solidification interface within 80 m from the exit of mold (2). If the conditions are maintained, the molten metal will solidify only in one direction in the drawing direction, and a unidirectionally solidified structure consisting of crystals extending to a substantially infinite length in the drawing direction will be obtained.

In the present invention, beryllium copper alloy is 0.1% by weight.
This refers to all copper alloys containing beryllium. Further, the ingot drawing direction may be in the horizontal direction as shown in FIG. 1, or may be in the vertical direction. Yet another mold (2)
It is also possible to use a model with a water-cooled carbon mold at the outlet on the drawer side and directly water-cool the continuous ingot that comes out of that outlet. Even if the molten metal moves outward, it is quickly solidified by the water-cooled carbon mold, which prevents the dangerous breakout of the molten metal from scattering.Furthermore, as shown in the second example below, Mold (2)
A water-cooled carbon mold can also be used. However, in this case, it is necessary to control the amount of cooling to maintain the inner wall surface of the mold at a temperature that does not allow the molten beryllium copper to solidify.

Preferred embodiments of the present invention are shown below.

(Example) Example 1 Cu-1, 85% Be-0,2 was placed in a holding furnace with a capacity of 150 kg.
A molten beryllium steel alloy with 5% CO is placed in the holding furnace and maintained at 1200°C.The outer surface is protected with anti-oxidation ceramic paint at the bottom of this holding furnace, and the inner dimensions are 100 tm wide and 1 tm high.
A non-water-cooled carbon mold with a length of 5 m was installed vertically, and a dummy par was first inserted into the mold.
While injecting cooling water at a flow rate of 301/min from the water cooling nozzle located at 5 mm, the dummy par was
Continuous casting was performed by drawing continuously at a speed of 0 mm/min. When the obtained continuous ingot was examined under a microscope, the overall result was 90.
% was composed of a unidirectional solidified structure parallel to the drawing direction, and the thickness of the reverse segregation layer was about 0.02 m.

After casting, the mold was dismantled and the position of the solidification line was examined, and it was found to be maintained at approximately 81 mm from the mold outlet. In addition, the continuous ingot was cut into lengths of 1 m and cold-rolled as they were until the thickness ranged from 15 mm to 2.5 mm.
No surface cracks or edge cracks occurred at all. On the other hand, when a continuous ingot was annealed at 800° C. for 2 hours and then cold rolled, cold rolling was possible from 15 mm to 0.6 m without producing surface cracks or edge cracks.

In addition, using the same casting equipment, we prototyped several types of continuous ingots with varying crystal unidirectionality by changing the withdrawal speed and cooling water flow rate, and investigated the rolling limit that causes edge cracking due to cold rolling.
At the same time, the thickness of the reverse segregation layer was also measured and shown in Table 1.

Table 1 *1 Thickness of the ball 15m *26 Thickness of the Shoutama 15Q Hanashihi bullfighting 800
°C x 211 m Example 2 Cu −0,42%Be − was placed in a holding furnace with a capacity of 150 kg.
A molten metal of 1,83% Ni was added and maintained at 1230°C. The inner diameter is 40mm and the outer diameter is 1mm installed horizontally at the bottom of this holding furnace.
A cylindrical water-cooled carbon mold with a length of 80 mm and a length of 100 nm is installed, and a pure copper water cooler is tightly attached to the outer surface of the water-cooled carbon mold.The dummy par is intermittently pulled out using pinch rolls, and an injection is made at a position of 80 mm from the mold outlet. Continuous casting was performed by injecting cooling water from a type water-cooled nozzle at a rate of 201/min. Cooling water amount of pure copper water cooler is 30! Bars with different degrees of unidirectional solidification were created by varying the intermittent drawing parameters while maintaining a constant value of /min. For each bar, the thickness of the reverse segregation layer and the diameter that could be directly swaged and drawn as an ingot without cracking were evaluated, and the results are shown in Table 2.

Table 2 Example 3 A mold consisting of an adiabatic mold made of 5iJa and a water-cooled carbon mold located on the outlet side was installed horizontally at the bottom of a holding furnace with a capacity of 50.
A molten metal of a beryllium copper alloy consisting of -2.63% Co was charged and kept at 1200° C., and continuously drawn out using pinch rolls in the same manner as in the previous example. At this time, the flow rate of the water-cooled shower installed at a position 20 m from the mold outlet was fixed at 2017 minutes, and the withdrawal speed and the amount of cooling water in the water-cooled carbon mold were varied to obtain continuous ingots with various solidification structures. The cross-sectional shape of the ingot is width 100t x height 2
0m flat plate shape, 5isN4 insulation mold has a wall thickness of 3
0 mm, length 50 m, water-cooled carbon mold wall thickness 3 (1 m,
It is 50m long. Solidification structure of each continuous ingot obtained,
The relationship between direct cold rolling limits was as shown in Table 3.

Table 3 (Effects of the Invention) As is clear from the above description, the present invention is capable of continuously casting a continuous ingot of beryllium copper alloy with extremely good cold workability with a high yield. It will greatly contribute to the development of industry as it solves the problems of conventional production of this type of beryllium copper alloy ingot.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the continuous casting method of the present invention. (1): Holding furnace, (2): Mold, (3): Pinch roll, (4): Cooling nozzle.

Claims (1)

[Claims] 1. The thickness of the reverse segregation layer on the outer periphery of the ingot is 0 to 0.05 mm, and 80% or more of the entire ingot has a unidirectional solidification structure extending parallel to the ingot drawing direction. A continuous ingot of beryllium copper alloy characterized by the following. 2. By continuously drawing molten beryllium copper alloy from a mold whose inner wall surface is maintained at a temperature that does not solidify the molten metal and rapidly cooling it at the mold outlet, a temperature parallel to the drawing direction is created inside the ingot. A continuous casting method for beryllium copper alloy characterized by unidirectional solidification near the exit of the mold while forming a gradient. 3. The continuous casting method for beryllium copper alloy according to claim 2, wherein an adiabatic mold or a heating mold is used as the mold, and the slab at the exit of the mold is directly cooled with water. 4. Continuous casting method for beryllium copper alloy according to claim 2 or 3, which uses an adiabatic mold or a heating mold with a continuous water-cooled carbon mold at the outlet and directly cools the ingot at the outlet of the water-cooled carbon mold with water. .