JPH0647165B2 - Manufacturing method of metal laminated composite - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a metal laminated composite material, and to a technique for obtaining a laminated composite material having a uniform and strong bonding interface by a relatively simple means. Is.

(Prior Art) A metal laminated composite material in which metal materials having different compositions are laminated and compounded can have the characteristics that each compounded material has, and exhibit characteristics that cannot be realized by a single material. Therefore, various studies have been conventionally conducted on the production thereof.

As a general method for obtaining such a laminated composite material, the ingots obtained by casting each material into individual pieces are chamfered, or subjected to preforming such as rolling or extrusion, and then face-to-face,
Then, hot or cold forming is performed to obtain a plate-shaped or rod-shaped composite material having a desired shape.

Further, such a general method requires a considerable number of man-hours for preforming by chamfering, rolling, or extruding, and is extremely costly. Therefore, there are some methods for simply obtaining a composite material by omitting the face-matching step. Among them, the most simple method is proposed, in which the metal base material is immersed in a container containing a molten metal of a different metal and then pulled up to cause the molten metal of the different metal to adhere and solidify on the surface of the metal base material. Although a method has been proposed, it is almost impossible to control the thickness of the metal deposited on the base material surface by this method, and basically the thickness of the deposited metal layer is thin. However, there is a serious defect that a partial thickness unevenness occurs.

As another method, a so-called casting method has been proposed in which a metal base material is set in a mold with a space therebetween, and a molten metal of a different metal is injected into the space and then solidified to form a composite.

This casting method makes it possible to combine different metals to a desired thickness by appropriately adjusting the space between the mold and the base material, and also to form multiple layers by combining a suitable number of base materials and changing the type of base material. This is an extremely total means such as the ability to obtain a composite material. Furthermore, the heat of the molten dissimilar metal injected into the base metal space forms an alloyed layer at the contact interface with the base material, so the bond is strong. It has various excellent advantages such as

(Problems to be Solved by the Invention) The inventors have focused on various advantages of the above casting method,
When the manufacture of the laminated composite material by this method was examined, it was found that the casting method also had some problems.

That is, when a highly active metal material such as an aluminum material is used as the metal base material, an oxide film layer is formed on the surface of the base material. Although the oxide film is destroyed and metal-metal contact between the base metal and the molten metal is obtained and an alloying layer is formed, a uniform alloying layer is not formed overall, and the oxide film is partially formed on the boundary surface. A strong bond cannot be obtained because it remains. Further, even in a material obtained by hot-cold forming processing of such a composite material into a final product, a partially or continuously bulged portion is generated on the surface of the product, resulting in a defective product.

(Means for Solving Problems) The present invention is a so-called casting in which a metal base material is placed in a mold with a space, and a molten metal of a different metal is cast into the space formed by the mold and the base material. In the method of manufacturing a metal laminated composite material by the method, with the molten fluoride held on the upper surface of the molten metal to be injected into the space of the mold, the molten metal is poured from the lower end of the base material by an appropriate method such as a submersion method. The casting is completed by shifting upward.

(Operation) In the present invention, casting is performed by moving the molten metal from the lower end of the metal base material such as aluminum to the upper portion in a state where the molten fluoride layer is held on the molten metal surface as described above. First, the surface of the base material first comes into contact with the molten fluoride layer, and the strong cleaning action of the fluoride bath destroys and removes the oxides formed on the surface of the base material and immediately exposes the metal surface to the molten metal. As a result of the contact with the metal, a substantially uniform alloyed layer is formed with little or no oxide at the interface between the solidified base material and the dissimilar metal. Is obtained. The laminated composite material thus obtained does not cause defects such as a bulged portion on the surface even when the final product is finished by hot and cold forming. This is due to the conventional method in which the non-bonding part is created at the boundary part due to the oxides that are mostly present at the boundary surface between the base metal and the laminated metal, and the gas present in the minute gap in that part expands and aggregates during the subsequent hot working. Then
Further, when peeled off, surface defects are generated as bulging portions such as so-called blisters.However, according to the present invention, the oxide layer is completely removed in the cast state as in the case of the assistant and the interface is not miscellaneous at the interface. Is completely integrated as an alloyed layer of the base metal and the laminated metal, and it is considered that this is due to the absence of such a non-bonded portion containing gas that causes blistering.

The present invention will be described in more detail with reference to the drawings. FIG. 1 is an example of a method for producing a laminated composite material by the casting method of the present invention, in which a backing plate 1 is installed at one end on the short side, and corresponding molten metal introduction holes 2 are provided on both lower side surfaces of the plate 1. Using a rectangular metal mold 4 configured to introduce the metal melt into the interior through the melt injection hole 3, the metal mold 4 is preheated to an appropriate temperature and an aluminum plate-shaped ingot is used as a base material 5. As a set, a mold long side wall and an appropriate space are formed in the central portion of the space surrounded by the mold inner wall and the backing plate 1, and a constant thickness is provided from the molten metal injection hole 3 to the bottom of the mold 4. After injecting the molten fluoride 6 so as to form the molten metal, the molten metal 7 of different kinds to be laminated is injected. In this way, the molten fluoride 6 previously injected is retained as a floating layer on the surface of the molten metal due to the specific gravity as the metal melting increases, as shown in FIG. In this state, the molten metal 7 is further poured to the upper end surface of the base material 5 to complete the casting. When casting is performed as described above, the surface of the base material 5 first comes into contact with the molten fluoride 6, the oxide film on the surface is completely destroyed and removed, and the metal surface comes into contact with the molten metal in a completely exposed state. In addition, a metal-laminated composite material is obtained in which an alloyed layer is formed almost uniformly and firmly bonded without causing a non-bonded portion due to residual oxide at the contact interface.

In the present invention, the metal base material to be set in the mold is a plate-shaped, hollow or solid columnar cast obtained by a general casting method as it is, or is subjected to chamfering or preliminary forming processing. It is applied to obtain a desired size and shape.

Further, the die used is not limited to the above example, and various types such as a type in which the molten metal is introduced from a pouring hole provided in the bottom of the die and a type in which the molten metal is introduced into the bottom by a siphon method are conceivable. In any case, it is important to complete the casting by allowing the molten metal to move from the lower end of the base metal toward the upper end while the molten fluoride is held on the upper surface.

In the present invention, the molten fluoride held on the upper surface of the molten metal has a lower melting point than the metal to be laminated and reacts with the surface of the active metal material such as aluminum or aluminum alloy which is the base material in the molten state to form in its surface layer. It must have a strong cleaning action to destroy and remove the oxide film. As such a fluoride, for example, KF-A1
The F ₃ -based flux has a remarkable effect of removing such an oxide and exhibits a corrosion resistance against the aluminum base material, so that there is no problem even if a part of the F ₃ -based flux remains. Since the flux of this system has a eutectic point (562 ° C.) in the vicinity of 56% by weight of KF, selecting a composition in the vicinity of the eutectic point does not require the metal injection temperature to be so high and is economical. Of course, in addition to such a binary flux, CaF ₂ , NaF, LiF, LiAlF ₄ , Li ₃ Al
It is also possible to use a multi-component fluoride flux containing a fluoride such as F ₆ or a compound obtained by complexing these simple compounds.

These fluorides are supplied in a molten state into the mold and held on the surface of the molten metal of the dissimilar metal as in the above-mentioned casting example, and are also sprayed in the form of powder or flakes on the bottom of the preliminary mold. Good. Further, a method of suspending in a powder state in a solvent such as alcohol or water and applying this to the surface of the base material may be adopted. Even in such a case, the fluoride on the surface of the base material is instantly melted by the heat of the injected molten metal, reacts with the oxide film existing on the surface of the base material, and has a cleaning action. The molten metal is retained on the upper surface of the molten metal as it is poured into the molten metal, which is the same as the above-mentioned casting example.

In the present invention, the base material may already have a plurality of layers and the molten metal may be laminated and cast, and a base material, particularly a thin metal base material, may be used on one or both sides of the molten metal. it can. By doing so, for example, the base material is a thin plate of pure aluminum or an aluminum alloy having a clear composition, and the molten metal is obtained from scrap or the like, and the molten metal is set between the base materials set on both sides of the mold. By injecting, it is possible to obtain a laminated composite material having a low cost and a well-defined surface and composition, and therefore, it can be advantageously applied to various uses. Of course, not only scrap but also alloy material having characteristics such as heat resistance and strength can be used. If the base material has a high degree of warmth, alloying at the joining surface with the laminated metal with the required alloy composition is easy and reliable, so the thickness of the base material is relatively large relative to the thickness of the metal to be laminated. If it is large or has a large heat capacity, it is desirable to preheat the base material to an appropriate temperature. The heating temperature for such a base material changes due to the relative thickness difference, heat capacity difference, etc. and cannot be determined in a single case.However, if the interface alloying layer needs to be thicker, the heating temperature is set to a higher temperature and the base material is heated by the molten metal. Is
It is preferable to preheat so as to be near the solidus temperature or slightly higher than this temperature when coming into contact with the molten metal layer.

(Example) A specific example of the present invention will be described below.

Example 1 A JIS3003 aluminum alloy was melted by a conventional method,
Semi-continuous casting with a cross section of 240 mm x 60 mm, length 100
The ingot was 0 mm. After the degreasing, the ingot was heated to a temperature of 480 ° C. in a preheating furnace, and the heated ingot was preheated to almost the same temperature (with a section of 300 mm × 100 mm, the distance from the patch plate portion to the short side portion of the die). 1000mm) and set separately as shown in Fig. 1 and melted separately (composition: KA
A mixture of IF ₄ 75 wt% and K ₃ AIF ₆ 25%, melting point: 565 ° C.) was first introduced into the mold at a height of 1 from the injection hole of the mold.
It is supplied so that it becomes 0 mm, and then JIS 404 at 730 ° C.
A 5 aluminum alloy melt field was similarly supplied from the injection hole. By doing so, the molten fluoride supplied previously is retained as a molten fluoride layer on the upper surface of the molten metal, and the molten fluoride layer cleans and raises the surface of the base metal as the molten metal is poured and the mother fluoride surface rises. A laminated metal layer was formed on both surfaces of the material. A cross-section sample of the laminated metal material obtained in this way was cut and the interface between the base material and the laminated material was observed under a microscope to confirm that a uniform alloyed layer was formed and that the joint was strong and stable. Was done. In addition, when multiple cross-section samples of such laminated composite material were taken and visually observed, non-bonded parts (including gaps) due to residual oxides were observed.
There was nothing.

After laminating the laminated composite material by a conventional method, hot and cold rolling were carried out to obtain a laminated thin plate material having a thickness of 0.2 mm. The surface of the laminated sheet material was not only hot rolled but also cold rolled. It was possible to obtain a laminated composite material product which was smooth and had no bulging portion or convex portion and which was excellent in quality.

Incidentally, in contrast to the above-mentioned one according to the present invention, as a comparative example, a macroscopic observation similar to the above was carried out for a comparative material obtained in the same manner as the composite material manufacturing conditions except that a fluoride bath was not used at the time of casting, It was found that a gap was found in most of the boundary between the base metal and the laminated metal, and the joining was insufficient.

A similar gap was observed by microscopic observation, and the presence of an oxide layer was confirmed even in a place where no gap was formed.

From this, it can be understood that the joining is uncertain in the metal casting composite material by the conventional casting method which does not use the molten fluoride bath. Furthermore it was subjected to rolling in the same manner as also above for the comparative laminate, in hot-rolled 1 m ² per
Five or more bulges were generated, and in the cold-rolled material, they were in an extended and expanded state, and the quality was remarkably inferior.

(Effects of the Invention) As described above, according to the present invention, the desired metal laminated composite material can be obtained by an advantageous process in which the face-to-face matching process is omitted, and moreover, it is formed on the base metal surface at the interface between the base metal and the laminated metal. It is possible to effectively remove the existing oxide layer to prevent the generation of non-bonded portions at the interface and to form a uniform alloyed layer to strengthen and obtain a laminated composite material having a reliable bonded interface. It can be said that the invention is industrially effective.

[Brief description of drawings]

The drawings show an example of a mold apparatus for carrying out the method for producing a metal laminated composite material by the casting method according to the present invention. FIG. 1 is a plan view thereof and FIG. 2 is a longitudinal sectional view thereof. In the figure, 1 is a backing plate, 2 is a molten metal introduction hole, 3 is an injection hole, 4 is a mold body, 5 is a base material, 6 is a molten fluoride, and 7 is a molten metal of a different kind.

Claims (1)

[Claims] 1. When a molten metal of a different kind is cast into a space formed by a mold and a metal base material to obtain a metal laminated composite material, the molten metal is held on its upper surface with a molten fluoride layer. A method for producing a metal-laminated composite material, characterized in that in the state, the base material is moved upward from the lower end portion and cast.