JPH0481288A - Method for joining steel material with aluminum material - Google Patents

Abstract

PURPOSE:To easily execute joining to develop sufficient joint strength with high quality by disposing a clad material laminated with a steel member and aluminum member between a steel maternal and an aluminum material. CONSTITUTION:The clad material 3 consisting of the previously joined steel member 4 and aluminum member 4 is disposed between the steel material 1 and the aluminum material 2. The clad material consisting of the members 4, 5 respectively having 0.8 to 3.0mm thickness is more adequate. These materials are so laminated that the above-mentioned steel member 4 and steel material 1 come into contact with each other and the above-mentioned aluminum member 5 and aluminum material 2 come into contact with each other. Among these materials, the metallic materials of the same kind are joined to each other by laser welding 8. The laser welding conditions are selected from the kinds, chemical compsns., thicknesses, surface condition, etc., of the members to be joined at such adequate conditions under which the melting of the different metals beyond the joint surfaces of the clad substrate does not arise. The steel materials are joined to each other and the aluminum materials to each other by melting in this way and, therefore, the defectless joint is obtd. without forming a hard and brittle intermetallic compd. in the weld metal.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is directed to bonding and integrating a steel material such as carbon steel or stainless steel and an aluminum material made of aluminum or an alloy thereof. It relates to a method of joining with other materials.

[Prior Art] Conventionally, methods for joining dissimilar metals have been proposed, particularly for joining steel-based materials such as carbon steel or stainless steel (hereinafter simply referred to as steel materials) and aluminum or its alloys (hereinafter simply referred to as aluminum materials).
The following method is known as a method for welding.

■ A so-called aluminized steel plate with an aluminum film formed on one side of the steel material is used as an insert material, and the steel plate side of this insert material is placed in contact with the steel material, and the aluminum film surface and the aluminum material are placed in contact with each other. , How to resistance spot weld.

(2) A method in which a clad material made of laminated steel and aluminum is used as an insert material, and the same metals of the welded material and the insert material are brought into contact with each other, and the two are resistance spot welded.

■ A method of friction welding steel and aluminum materials directly or with an insert material in between.

■ A method of ultrasonically welding steel and aluminum materials directly or with an insert material in between.

■ A method of electron beam welding or laser welding of steel and aluminum materials directly or with an insert material interposed between them.

[Problems to be Solved by the Invention] However, all of these methods have the following problems.

FIG. 8 is a schematic diagram showing the principle of resistance spot welding used in methods (1) and (2). That is, a cladding material 3 as an insert material is arranged between a steel material 1 and an aluminum material 2, which are members to be welded, and these are overlapped. The cladding material 3 is a laminate of a steel member 4 and an aluminum member 5.

Then, while applying pressure to the base material steel 1, aluminum material 2, and insert material 3 through the tip 6, electricity is applied to locally melt and integrate them. In this case, when the base metals are dissimilar metals consisting of steel material 1 and aluminum material 2, a hard and brittle Fe-Affiff compound 7 is generated in the weld metal, as shown in FIG. For this reason,
There are problems in that the resulting welded joints have large variations in strength and low ductility.

Further, there is a problem in that a space is required to position the chips 6 on both sides of these members during welding work, and the shape and dimensions of the joining members are limited.

Furthermore, there is also the problem that the commercial value deteriorates when the weld is directly on the outer surface because the impression of the weld remains on the surface and the appearance of the weld is poor.

Friction welding is a method in which one of the parts to be joined is rotated, the joint surface is heated by friction, the rotation is stopped at an appropriate temperature, and pressure is applied in the axial direction to perform welding, and the base metal melts. doesn't happen. Therefore, although it is possible to join steel materials and aluminum materials, it is necessary to rotate at least one of the base materials, and there is a restriction that it can only be applied to materials whose shape is generally rod-like or tubular.

■Friction welding is a welding method in which electrical energy is converted into ultrasonic vibration, which is mechanical energy, using a vibrator, and the ultrasonic vibration is transmitted to the welding area through a bar with an appropriately shaped tip, and the material to be welded is pressurized. It is.

The principle is that dirt is removed from the surface of the materials to be welded by friction caused by ultrasonic vibration, and when the oxide film is broken and a new surface is exposed, the materials to be welded are pressurized and joined together. Heat is generated locally, but the material to be welded does not melt.
The temperature of the entire material to be welded does not rise. Therefore, although it is possible to join steel materials and aluminum materials, there is a problem in that the shape of the material to be welded is limited to a thin plate or a thin rod shape, and is subject to restrictions on the shape of the material to be welded. In addition, similar to resistance spot welding in ■ and ■, work space is required on both sides of the workpiece during welding work, and this also limits the shape of the workpiece to be welded. There is a point. Furthermore, there is also the problem that if the welded part appears directly on the outer surface, the commercial value will deteriorate because the impression of the welded part remains on the surface and the appearance of the welded part is inferior.

■The electron beam welding law text states that laser welding is a so-called high-energy density welding method, and by concentrating the beam on an extremely small spot, the heated area can be narrowed down, resulting in deep weld penetration and high-speed welding. It is possible. However, when welding steel and aluminum materials, even if an insert material is inserted in the middle, hard and brittle Fe remains in the weld metal.
Since the -A intermetallic compound is formed, there are problems in that the joint strength is low and the stability is poor.

As mentioned above, conventional techniques have low joint strength and low reliability, and there are constraints on the space and shape of the joining members, and for example, they are not suitable for joining large area thin plates. This method is insufficient to obtain a high-quality welded joint in that when the welded part appears on the outer surface, an indentation remains and the commercial value deteriorates.

The present invention has been made in view of such problems, and includes:
In addition to having sufficient joint strength, it is possible to improve the degree of freedom in design by eliminating space and shape constraints on the joined members, and to avoid welds from appearing on the outer surface of the product. The purpose of the present invention is to provide a method for joining steel-based materials and aluminum-based materials.

[Means for Solving the Problems] The method for joining steel-based materials and aluminum-based materials according to the present invention includes a method for joining steel-based materials and aluminum-based materials, which are materials to be welded. A laminated cladding material is placed in contact with the steel-based member and the aluminum-based material, and the cladding material, the steel-based member, and the aluminum-based member are melted together. It is characterized by being joined and integrated by laser welding under unsuitable welding conditions. Note that the aluminum-based member refers to a member made of aluminum or an aluminum alloy.

[Function] In the present invention, a cladding material made of a steel member and an aluminum member that have been previously joined by another method is placed between the steel material and the aluminum material that are the members to be joined. In this case, the steel-based member and the steel-based material contact,
The aluminum-based member and the aluminum-based material are brought into contact with each other. After that, similar metal materials among these materials are joined by laser welding, but the laser welding conditions are such that the welding conditions exceed the joining surface of the clad material due to the type of target member, chemical composition, plate thickness, surface condition, etc. Select appropriate conditions to prevent melting.

Filler wire may be used if desired.

This results in a fusion bond between steel-based materials and aluminum-based materials, so that a hard and brittle intermetallic compound is not formed in the weld metal, resulting in a sound joint.

[Example] Examples of the present invention will be specifically described below.

Actual Example 1 - As shown in FIG. 1, between a steel material 1 and an aluminum material 2, a steel member 4 and an aluminum member 5 of the cladding material 3 face the same type of metal, respectively. The cladding materials 3 are arranged and overlapped as shown. The type and thickness of each material are shown in Table 1 below.

Table 1 Welding is performed between the steel-based member 4 of the cladding material 3 and the steel-based material 1, and between the aluminum-based member 5 of the cladding material 3 and the aluminum-based material 2 using a laser beam 8, respectively. In this case, the welding conditions are adjusted and set so that the tip of the melt fit does not exceed the thickness of each member 4, 5 of the cladding material 3.

As a result, the obtained bead 9 is melted only between the similar materials, and the steel member 4 and the aluminum member 5 of the cladding material 3 are melted.
The boundary between is not melted. Therefore, no intermetallic compounds are generated.

Table 2 below shows the results of investigating the joint strength by varying the thickness of each member of the clad material used in this example and comparing it with the conventional method.

As shown in Table 2, in the case of the comparative example using the conventional method, the joint strength was only about 50% or less than that of the base metal,
According to the present invention, a joint strength similar to that of the base material can be obtained, and it has been demonstrated that the joint quality is extremely good.

The thickness of each member 4.5 of the cladding material 3 shown in Table 2 is 0.0 mm or more and 5.0 mm or less, but the same effect can be obtained with thicknesses other than this.

However, if the thickness of each member 4, 5 of the cladding material 3 is in the order of 0.8 to 3.0, extremely high joint strength similar to the strength of the base material can be obtained. It is desirable to keep it within this range. If the thickness of each member 4, 5 of the clad material 3 is less than 0.8, the joint strength will be slightly lower, but this is because the width of the weld metal at the welding surface is smaller than the thickness of the base metal. Conceivable.

No. table on the other hand, Each member of cladding material 3 4゜ The thickness of 5 If the ratio is 4.0 or more, the joint strength will also be slightly lower.

This seems to be because rotational deformation was applied during the shear tensile test, and force was applied to the joint in the direction of peeling.

FIG. 2 shows the state of the joint joined in this manner. The welding conditions in this case are shown in Table 3 below.

Note that it goes without saying that the welding conditions are not particularly limited to these.

As shown in Table 3 and Figure 3, steel material 1 and aluminum material 2 are placed between steel material 4 and aluminum material 5.
The cladding materials 3 made of the following materials were arranged so that the same kind of metals were facing each other, and their end surfaces were brought into contact with each other. The types and thicknesses of each of these materials are shown in Table 4 below.

Thereafter, as shown in FIG. 4, similar metals were butted against each other and welded with a laser beam 8 in the same manner as in Example 1. The welding conditions at that time are as shown in Table 5 below.

As shown in FIG. 4, the steel material 1 and the steel member 4 were joined by the beats 10, and the aluminum material 2 and the aluminum member 5 were joined by the beats 10. These pairs of beats 10 are not connected to each other.

As shown in Table 5, a clad material 3 is placed between a steel material 1 and an aluminum material 2 so that the same metals face each other. The types and thicknesses of these materials are shown in Table 6 below.

First, as shown in FIG.
and were welded using a laser beam 8. As a result, beads 11 were formed. Next, as shown in FIG. 7, the aluminum-based member 5 of the cladding material 3 and the aluminum-based material 2 were overlapped and welded using a laser beam 8. As a result, beads 12 were formed. The bead 11 joins the steel material 1 and the steel member 4, and the bead 12 connects the aluminum material 2 and the aluminum member 5. There is no contact between both beads 11 and 12.

Table 6 The welding conditions are as shown in Table 7 below.

Further, although laser welding was performed in two steps here, it may be performed at once depending on the dimensions and shape of the materials. Furthermore, the order of welding is not limited to this, and the aluminum-based member 5 and the aluminum-based material 2 may be welded first.

Table 7 shows the shape after welding is completed, and there were no traces of welding, such as indentations or bulges, on the surface of the aluminum material 2 where the welded part appeared on the outside, and it could be supplied as a product as is. .

[Effects of the Invention] According to the present invention, sufficiently high joint strength can be obtained, the degree of freedom in material shape is large, and it is possible to join dissimilar materials between thin plates. Further, the present invention has excellent effects in that the welded portion has a good appearance and can be supplied as a product as is.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the joining method of Example 1, Fig. 2 is a schematic diagram showing the joining result, Fig. 3 is a schematic diagram showing the joining method of Example 2, and Fig. 4 is a schematic diagram showing the joining result. 5 is a schematic diagram showing the joining method of Example 3, FIGS. 6 and 7 are schematic diagrams showing the joining results, FIG. 8 is a schematic diagram showing the conventional joining method, and FIG. 9 is a schematic diagram showing the joining method of Example 3. The figure is a schematic diagram showing the joining result.

Claims (2)

[Claims] (1) A clad material in which a steel member and an aluminum member are laminated between a steel material and an aluminum material that are the materials to be welded, the steel member is the steel material, and the aluminum member is the aluminum member. A steel material, which is arranged in contact with an aluminum material, and is integrated by joining the cladding material, the steel material, and the aluminum material by a laser welding method under welding conditions that do not cause dissimilar metals to melt together. A method of joining materials with aluminum-based materials. (2) The method for joining steel-based materials and aluminum-based materials according to claim 1, wherein the cladding material is a steel-based member and an aluminum-based member each having a thickness of 0.8 to 3.0 mm. .