JPH0569161A - Production of composite metallic plate - Google Patents

Abstract

PURPOSE:To obtain Fe/Al clad steel plate excellent in workability by heating and press-fixing each material through electric heating to the optimum temperature. CONSTITUTION:Steel blanks 1, 3 are provided with two electric rollers 11, 14 and a steel blank 2 is provided with one electric roll. Power sources 21, 23 are connected between the respective electric rolls and current is made to flow between them, the aluminum plate is heated at an ordinary temperature -450 deg.C and the steel plate is heated at 600-910 deg.C and the clad steel is sent between pressing rolls and press-fixed at a draft below 30%. In this way, the Fe/Al clad steel plate suitable to workability and different uses can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to materials and light weights for electric devices,
The present invention relates to a method for producing a relatively thin composite metal plate, that is, a clad plate, which is made of aluminum or an aluminum alloy such as JIS standard 3003 and a plain steel plate such as a low-carbon steel plate, which are suitable for applications that take advantage of good thermal conductivity. It is a thing.

[0002]

2. Description of the Related Art There are various techniques for producing a composite metal sheet. For example, a method of producing a composite from the beginning of the production process is called a casting rolling method, and one material is suspended in a mold. There is a method of making an ingot that is slab-filled. Further, there is also a method generally called a hot rolling method in which raw materials are superposed at a stage of a slab having a thickness of several hundred millimeters and the periphery is welded to prevent oxidation, and then heated and rolled to bond.

Each of the above methods is premised on the subsequent steps such as rolling and annealing, and it is difficult to apply them to the compounding of materials such as aluminum and iron whose annealing temperatures greatly differ. is there. That is, the general annealing temperature of iron is 700 ° C, whereas the melting point of aluminum is 660 ° C.
That is all.

As a method applicable to a wide range of material combinations, an explosive deposition method utilizing high pressure generated when explosive explodes is known, and a clad of aluminum and iron such as a reaction plate of a linear motor car. Used in wood. However, a thick plate like this practical example (for example, aluminum 5 mm thick, steel plate 15 mm thick)
However, even if the final product can be obtained as it is, it is necessary to consider rolling the thin plate later, and the same problems as those of the above-described cast rolling method occur.

A method called lap rolling is known as a method applied exclusively to a thin plate clad material. This is a method in which sheets of material are stacked cold or warm, sent to a rolling mill, pressed, and pressure-bonded, and are usually continuously formed in a coil shape. 1 for sufficient bonding
The condition is that the reduction in the pass is made as large as possible. In the case of joining nonferrous metals to each other, it is often performed cold, but the steel sheet is often heated and warmed.

[0006]

In the above-mentioned lap rolling method, as its name implies, the driving force for joining is rolling, and heat only plays an auxiliary role when heating. That is, in the case of a steel plate or the like, since the deformation resistance is large and the rolling force is significantly large in the cold state, it is intended to facilitate heating by softening by heating to some extent.

Therefore, the joined materials have a structure in which the crystal grains are elongated and hardened even after heating, which is the case after cold rolling. For processing applications such as drawing, annealing must be performed for softening. I won't.

However, the temperatures suitable for annealing are completely different between aluminum and ordinary steel, and in the case of a composite metal plate of such different materials, it is not possible to perform annealing that satisfies the requirements of both materials. It is possible. Under these circumstances, the composite material of a thin plate of aluminum and ordinary steel has hardly been put into practical use at present.

[0009]

DISCLOSURE OF THE INVENTION The present invention is to solve the above problems, and manufactures a composite metal sheet by stacking and joining at least one aluminum or aluminum alloy sheet and at least one ordinary steel sheet. In the method described above, the aluminum or aluminum alloy plate is kept at room temperature or at 450 ° C. or lower, and the temperature of the ordinary steel plate is set to 600 ° C.
To 910 ° C. in an atmosphere having an oxygen concentration of 3% or less while being fed between pressure-bonding rolls and pressure-bonding at a reduction rate of 30% or less.

Further, as heating means, one or more current-carrying rolls are provided on at least one of the aluminum or aluminum alloy plate to be pressure-bonded and the steel plate of common steel, and a current is passed between the current-carrying rolls. It is also characterized by performing heating.

[0011]

In the present invention, the metal plates, which are the raw materials of the composite metal plate, are heated and superposed, and are fed between the pressure bonding rolls to be bonded. The heating temperature at this time is 450 ° C. for an aluminum or aluminum alloy plate at room temperature or 450 ° C.
Below ℃, 600 to 910 ℃ for ordinary steel plate
Even in this range, heating is preferably performed to 750 ° C or higher.
In the present invention, the main driving force for bonding is to increase the diffusion rate of atoms due to high temperature, and the heating temperature is higher than the conventional so-called lap rolling method. If the temperature is lower than the above, the bonding strength becomes insufficient, and if the temperature is higher than the above, the crystal grains become coarse, or in the steel sheet, the texture changes due to the microstructural transformation, which is not preferable in terms of material quality. Will also be difficult.

Further, in order to heat at such a high temperature, an oxidation preventing means is necessary, and the steps from heating to pressure bonding are performed in an atmosphere having an oxygen concentration of 3% or less, for example, a nitrogen gas atmosphere. For this reason, it is necessary to provide means such as putting the entire apparatus in a chamber with a protective atmosphere. In the low-temperature bonding method in which a new surface is generated on the bonding surface by a high reduction ratio to promote the bonding, the oxidation itself is small, so the prevention of the oxidation was not so important, but in the method of the present invention, the high temperature and the low pressure reduction ratio will be described later. Since it is a joint, it is important to prevent oxidation. It is desirable that the oxygen content in the atmosphere is as low as possible, but the practical limit is 3
%, And if it exceeds this, the oxidation of the plate becomes remarkable.

On the other hand, the reduction rate by the pressure roll is lower than that of the conventional lap rolling method, and the reduction rate, that is, the ratio of the difference between the total sheet thickness and the product sheet thickness is 30% or less,
It is preferably within the range of 20% or less. Reduction rate of 30%
The reason for this is that the material is often deteriorated due to the formation of a processed structure when the rolling reduction is high. In the method of the present invention, 20% or less is preferable in order to stop the rolling in the range where the formation of the processed structure is small. If the heating temperature of the material is sufficiently high, it is possible to normally perform pressure bonding if the reduction rate is 5% or more.
Conventionally, in aluminum diffusion bonding, etc., brushing has often been carried out for the purpose of removing an oxide film on the surface. However, in the experiments conducted by the present inventors, there was no need for such brushing under the above conditions, and good crimping was possible. It was

The process of the present invention as described above has a particularly favorable influence on the material. That is, while the conventional lap rolling method has a high reduction rate in crimping, even if heated, since it is below the recrystallization temperature, the crystal grains are in a stretched form and are in a work-hardened state. Therefore, in order to use it for general processing such as bending and squeezing, it must be annealed to be softened, but if the temperature is made sufficient to soften the steel, the melting point of aluminum will be exceeded. However, according to the electric heating method of the present invention, such a problem does not occur because the material can be heated to the optimum temperature for each of the plates and the final product can be left bonded.

Further, in the clad material of iron and aluminum, it is said that a brittle alloy layer is formed at the joining interface to impair the workability, but such a problem is not seen in the composite metal plate of the present invention. It was It is considered that the reason is that the method of the present invention is rapidly cooled by the pressure bonding roll after the iron and aluminum are contacted with each other, and is not kept at a high temperature for a long time.

As the apparatus for carrying out the method of the present invention, various kinds of heating means can be considered, but the method by electric heating previously developed by the present inventors is particularly suitable (Japanese Patent Laid-Open No. 2-307687). issue). In this, one or more current-carrying rolls are provided on each of a plurality of metal plates, and a composite metal plate is manufactured by continuously feeding current between the current-carrying rolls so that the metal plates overlap each other so that the metal plates overlap each other. Is the way. That is, as shown in FIG. 1, the metal plate 1 of the material is provided with two energizing rolls 11 and 14, and the metal plate 2 is provided with one energizing roll 12, and power sources 21 and 23 are connected between the respective energizing rolls. The composite metal plate 5 is manufactured by sending the current between the pressure-bonding rolls 4 so that the metal plates of the raw materials overlap each other while passing an electric current.

As the power source, either a low frequency AC power source or a DC power source can be used. The current of the power source 21 is one of the energizing rolls 1.
From 1 to the metal plate 1 of one material, through the portion of the pressure bonding roll 4, to the metal plate 2 of the other material to the other energizing roll 12. That is, the current values of the metal plates 1 and 2 of each material are the same. For example, metal plate 1 is steel plate 2
Is an aluminum plate, the steel plate has a higher electric resistance unless the aluminum plate is particularly thinner than the steel plate. Therefore, at the same current value, the steel sheet is heated more strongly. The required temperature is higher for the steel sheet, which is convenient, but the heating of the steel sheet is still insufficient in many cases. Therefore, the energizing roll 14 for auxiliary heating is provided, and the current is supplied from the power source 23 to assist the heating. In this heating method, the temperature of the metal plate of the material is constantly raised, so the heating temperature in the present invention is the temperature immediately before the pressure bonding roll.

Since this heating method requires only a commercial frequency power source, the cost of electrical equipment is significantly lower than that of high frequency heating, temperature control is easy, and the temperature distribution in the plate width direction is good. It is suitable to be applied to the above method.

FIG. 2 shows a case where a composite metal plate is manufactured by stacking three plates with the center being a steel plate, the front and the back being an aluminum plate.
Aluminum plate 3 heated by power supply 21 between 1 and 12
The steel plate 1 is heated by energizing it with a power source 22 between the energizing rolls 13 and 12. In this case, the phases of the power supplies 21 and 22 are determined so that the sum of the currents of the two power supplies 21 and 22 flows in the steel plate 1. Further, an energizing roll 16 for auxiliary heating is provided for auxiliary heating of the steel plate 1, and an electric current is made to flow by the power supply 25.

FIG. 3 shows a case where a composite metal plate is manufactured by stacking three plates, with an aluminum plate at the center and a steel plate on the front and back sides. In this example, the aluminum plate 2 is not heated, and the front and back steel plates 1 and 6 are connected to the current-carrying rolls 11 and 13.
A power supply 26 is energized between them to heat them. Further, energizing rolls 14 and 15 for auxiliary heating are provided and heating is performed by the power supplies 23 and 24, but in this example, it is not always necessary if the front and back steel plates 1 and 6 have the same thickness.

[0021]

【Example】

(Example 1) An aluminum plate having a thickness of 0.4 mm and a width of 280 mm and a thickness of 0.4 mm and a width of 30 were measured by the apparatus shown in FIG.
A two-layer composite metal plate was manufactured from a 0 mm low carbon steel plate (corresponding to JIS standard SPCE). That is, in FIG. 1, the metal plate 2 as a raw material was manufactured as an aluminum plate and 1 as a low carbon steel plate. The heating temperature of the aluminum plate is 200
C., the heating temperature of the steel sheet was 800.degree. C., and the heating and pressing were performed in a nitrogen atmosphere having an oxygen concentration of 0.1% or less. The rolling reduction with the pressure bonding roll is 10%. The characteristics of the product were examined, but no peeling occurred even after 90-degree bending and bending back test. Although cold rolling was performed, peeling did not occur in this case as well. Other tests such as a peel strength test, an Erichsen test for examining workability, and a deep drawing (Swift cup) test were performed, and as shown in Table 1, good properties were shown. The Erichsen test and the deep drawing test were carried out with the aluminum plate side being the outer surface that was drawn.

[0022]

[Table 1]

(Embodiment 2) Using the apparatus shown in FIG. 3, low carbon steel plates having a thickness of 0.4 mm and a width of 300 mm are used as front and back metal plates 1 and 6, and aluminum having a thickness of 0.5 mm and a width of 300 mm is used. A three-layer composite metal plate was produced with the plate as the center plate 2. The heating temperature of the steel sheet is 800 ° C., and aluminum remains at room temperature. The conditions of the heating atmosphere and the rolling reduction are the same as in Example 1. As shown in Table 1, the product characteristics were good.

(Comparative Example 1) Using a metal plate made of the same material as used in Example 2, a manufacturing process of a three-layer composite metal plate of a low carbon steel plate and an aluminum plate was carried out. The apparatus shown in FIG. 3 was used as in Example 2, but the heating temperature of the steel sheet was 5
The aluminum plate was kept at room temperature at 50 ° C., and the rolling reduction was 10% as in Example 2 (Table 1). The atmosphere during heating is the same nitrogen atmosphere as in Example 2. The result was that good bonding was not obtained, and the film was immediately peeled off by bending.

(Comparative Example 2) The conditions such as material and heating temperature are the same as those in Comparative Example 1, but the rolling reduction is 35%. As for the product characteristics, as shown in Table 1, although the materials were joined, they were processed at a temperature lower than the recrystallization temperature, so that the material hardened and the workability was poor.

[0026]

According to the method of the present invention, when producing a composite metal plate of aluminum or aluminum alloy and a steel plate of ordinary steel, each metal plate of the raw material is sufficiently heated and then pressure-bonded with a small reduction rate. Therefore, it is possible to form a composite without impairing the original characteristics of each material. Therefore, a composite metal plate suitable for various applications such as deep drawing can be manufactured.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of an apparatus for carrying out the method of the present invention.

FIG. 2 is a conceptual diagram showing an example of an apparatus for carrying out the method of the present invention.

FIG. 3 is a conceptual diagram showing an example of an apparatus for carrying out the method of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location // B23K 103: 20 (72) Inventor Tadao Kiriyama 1 Fuji-machi, Hirohata-ku, Himeji-shi, Hyogo Shin-Nihon Hirohata Works, Ltd.

Claims (2)

[Claims] 1. A method for producing a composite metal plate by laminating at least one aluminum or aluminum alloy plate and at least one plain steel plate, and manufacturing the composite metal plate, wherein the aluminum or aluminum alloy plate is kept at room temperature or 450 The composite metal is characterized in that the temperature of the steel plate of ordinary steel is heated to 600 to 910 ° C. in an atmosphere having an oxygen concentration of 3% or less, and is fed between pressure rolls to perform pressure bonding at a reduction rate of 30% or less. Method of manufacturing a plate. 2. One or more current-carrying rolls are provided on at least each of the steel plates of ordinary steel among the aluminum or aluminum alloy plates and the steel plates of ordinary steel to be crimped, and a current is passed between the current-carrying rolls for heating. The method for manufacturing a composite metal plate according to claim 1, wherein.