JP3174140B2 - Composite metal plate with excellent bonding strength - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to provide a composite metal sheet which is lighter than the conventional use of thin steel sheets, and is used as a material for a structure requiring machining and welding. Suitable for.

[0002]

2. Description of the Related Art Weight reduction of thin steel sheets used as structural materials has been a major issue, and various means have been proposed. One of the means for reducing the weight is to partially use aluminum. However, there are cases where not only aluminum but also iron is used as a material among the structures. In this case, it is necessary to join iron and aluminum, but both iron and aluminum have low joining strength due to welding, so that sufficient joining strength cannot be expected. For these reasons, at present, aluminum can only be used for limited applications.

[0003] It is considered that this problem can be solved if there is a two-layer composite plate in which one side is made of an iron layer and one side is made of an aluminum layer and the joining strength is strong. At present, with respect to a thin plate in which iron and aluminum are combined, a composite plate of iron and aluminum manufactured by a lap rolling method is known. For example, as disclosed in Japanese Patent Application Laid-Open No. 63-157774, a method in which an aluminum material is heated to about 350 to 550 ° C. and hot-rolled and joined to an iron material,
As disclosed in Japanese Patent No. 52679, there is a method in which the surface of an iron material is preliminarily plated with aluminum, which is heated to about 500 ° C., hot-rolled with the aluminum material, and joined. However, although the composite plate manufactured by these methods does not peel off in a process such as a gentle bending such as performing a single 180 ° bending as shown in the example of Japanese Patent Publication No. 56-52679, the composite plate is not bent. In a process such as bending back or a process such as deep drawing, the joint strength is not always sufficient. in this way,
A composite plate composed of two layers of iron and aluminum having a sufficient joining strength as a joining material has not been known so far.

[0004]

SUMMARY OF THE INVENTION Under such circumstances,
An object of the present invention is to provide a two-layer composite metal plate of iron and aluminum having good bonding strength.

[0005]

SUMMARY OF THE INVENTION The present invention has been accomplished to achieve the above-mentioned object, and comprises two sides made of iron on one side and aluminum on one side.
A composite metal plate comprising layers, wherein a diffusion layer having a maximum hardness at a bonding interface within a specific range is present.

[0006]

The present inventors have found that by providing a diffusion layer having a hardness within a specific range at the interface between iron and aluminum, a composite plate of iron and aluminum having extremely excellent bonding strength can be obtained. The present invention is based on this finding, and will be described in detail below.

In the present invention, the composition of the iron material and the aluminum material is not particularly limited. The iron plate used as the material of the composite plate of iron and aluminum may be one manufactured by a normal hot rolling or cold rolling process, and may be either a cold-rolled material or an annealed material. Further, the method of manufacturing the composite plate may be any method. However, the maximum hardness (Hv) of the diffusion layer in the case of a composite plate must be 200 or less.

The present inventors have proposed an iron layer (SPCC) having a thickness of 0.25 mm and an aluminum layer (A1) having a thickness of 0.5 mm.
050P-H24) with the device shown in FIG.
By changing the heating conditions of each layer, the state of the diffusion layer at the interface was changed, and the bonding strength of each was evaluated. One example of the result is shown in FIG. As can be seen from FIG. 1, if the maximum hardness of the diffusion layer at the bonding interface is 200 or less in Hv, good bonding strength can be obtained. Similarly, for iron and aluminum made of different materials, the maximum hardness of the diffusion layer
The inventors have found that a good bonding strength can be obtained if the Hv is 200 or less, and have reached the present invention.

The energizing and heating equipment shown in FIG. 2 is provided with energizing rolls 11 and 12 on the iron layer 1 and the aluminum layer 2 of the material, respectively, between the two rolls 3 which perform both energization and pressurization. Then, the two layers 1 and 2 are continuously fed and pressure-bonded to produce the composite plate 4. As the power supply, either a low-frequency AC power supply or a DC power supply can be used. The current of the power source 21 passes through the iron layer 1 and the aluminum layer 2 from the energizing roll 11 to the iron layer 1 and reaches the energizing roll 12. In this case, the electric resistance of the iron layer is higher than that of the aluminum layer. Therefore, when the thickness of the iron layer is equal to or smaller than that of the aluminum layer, the iron layer generates more heat and becomes higher in temperature. If the heating temperature of the iron layer does not reach the target temperature, the auxiliary heating is performed by energizing the power supply roll 13 provided for the auxiliary heating from the auxiliary power supply 22.

When joining an iron layer and an aluminum layer,
The joining method is not particularly limited as long as the condition of the maximum hardness of the diffusion layer is satisfied, and a method of applying an external force between two rolls as shown in FIG. good. The method of heating the joining material may be any method such as electric heating, induction heating, and heating by a heating furnace.
By forming the diffusion layer at the interface under the above conditions, one side having excellent bonding strength is formed of the iron layer and one side is formed of the aluminum layer.
It can be a composite board of layers. Hereinafter, examples of the present invention are shown together with comparative examples.

[0011]

EXAMPLE A two-layer composite plate made of an iron layer and an aluminum layer as shown in Table 1 was manufactured. These materials were wound in a coil shape and heated continuously by an electric heating device as shown in FIG. 2 while unwinding the coil before joining.
Immediately after the heating, the iron layer and the aluminum layer were continuously joined by an external force by two rolls contacting from both sides as shown in FIG. . The composite plate after joining was immediately forcibly cooled at 15 ° C./s by gas.

Sample Nos. 2 to 10 fall within the scope of the present invention, and Samples 11 to 16 fall outside the scope of the present invention. After joining, the joining strength of the obtained composite board is shown in Table 1.
As can be seen from Table 1, excellent bonding strength is exhibited when the maximum hardness of the diffusion layer at the interface of the composite plate is 200 or less in Hv.

[0013]

[Table 1]

[0014]

As described above, the composite plate of the present invention comprising two layers of iron and aluminum has excellent joining strength and workability.

[Brief description of the drawings]

FIG. 1 is a diagram showing the effect of the maximum hardness of a diffusion layer at an interface on the bonding strength of a composite plate.

FIG. 2 is a diagram showing an example of an apparatus that can be used for manufacturing a composite plate.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-317692 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 20/00-20/04

Claims (1)

(57) [Claims] 1. A composite metal plate comprising two layers of iron on one side and aluminum on one side, wherein a diffusion layer having a maximum hardness (Hv) of 200 or less is present at an interface between the iron layer and the aluminum layer. Composite metal sheet with excellent bonding strength.