JPH067952A - Method for welding multi-ply steel sheet - Google Patents

Abstract

PURPOSE:To strengthen the spot welded part of multi-ply steel sheet and an aluminum base metal and an iron base metal by limiting the combination of the same kind of materials with each other and welding current range. CONSTITUTION:The spot-welding between multi-ply sheets having three or more layers and the iron base metal at the most outer layer by laminating and joining the aluminum base metal layer 2 and the iron base metal layer 1 or this multi-ply steel sheet and the iron base metal or between two-layer multi-ply steel sheets consisting of the iron base metal and the aluminum base metal or the multi-ply steel sheet and the iron base metal or the aluminum base is executed by limiting the combination of the same kind of materials and the welding current range. Thus the strengthened welded part can be obtd. without forming brittle intermetallic compound at the welded part 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for welding a multi-layered steel sheet used for automobiles, trains, cookers, etc. for weight reduction and improvement of heat conductivity, and for assembling cars, trains, ships, etc. The present invention relates to a dissimilar material joining method of an iron-based material and an aluminum-based material via a multi-layer steel sheet.

[0002]

2. Description of the Related Art Recently, due to a demand for reducing the weight of materials used for automobiles, trains, ships, etc., the use of aluminum materials, or the combination of a plurality of metals mainly composed of aluminum materials, such as aluminum layers or It has been proposed to use a multi-layer steel plate formed by laminating and joining an aluminum alloy layer and a stainless layer or a steel layer. In connection with these, JP-A-58-16358
There is a dissimilar material joined body in which a light metal portion and a heavy metal portion are joined by welding through a joining member composed of a light metal portion and a heavy metal portion which are metallurgically joined as described in Japanese Patent No. 4).

Further, as disclosed in Japanese Patent Laid-Open No. 64-66076, at least one side surface of a steel member is coated with an aluminum-based material, and the aluminum-coated side surface is joined with an aluminum member by welding. There is a metal junction structure.
Similarly, as in Japanese Patent Laid-Open No. 1-289574, an aluminum profile formed by integrally forming a metal material for joining, which is the same as the vehicle body for joining an aluminum structure and a metal structure different from aluminum, into aluminum There is a vehicle body joining method in which a joining metal material of an aluminum profile and a metal body different from aluminum are weld-joined to each other for use in a joining portion of a building body.

[0004]

As described above, the aluminum members and the iron-based metal structure are welded to each other as described above, but the compounding of Fe and Al in the joining member is due to extrusion. Therefore, there are problems that the bonding strength of Fe / Al is weak, and that the Al layer is very thin, which makes welding difficult. In addition, no clarification has been made regarding welding of two-layer steel sheets to each other or welding of three-layer steel sheets to each other.
Furthermore, the joint shape is likewise not described in detail. In addition, when the aluminum member and the iron-based metal structure are welded and joined by the above-mentioned method, the size and shape of the Fe / Al composite material for joints used are limited, so that this composite material is manufactured in large quantities. There is a problem that you cannot do it.

[0005]

[Means for Solving the Problems] As a result of intensive studies on the above problems, the inventors of the present invention have conducted researches on welding of multi-layered steel plates to each other or to multi-layered steel plates and iron-based metal or aluminum-based metal. At the time of welding, by combining similar materials and limiting the range of the welding current value, the formation of brittle intermetallic compounds formed in the welded part was suppressed, and the strength deterioration of the joint part due to it was prevented. Further, in order to enable Fe-Al dissimilar material joining without forming a brittle intermetallic compound in the welded portion, Fe is added to the Fe side of the Fe / Al two-layer composite steel sheet.
Is to solve the above problem by welding Al to the Al side and limiting the welding current value.

The gist of the invention is as follows: (1) Multi-layered steel sheets of three or more layers, which are formed by laminating and joining an aluminum-based metal layer and an iron-based metal layer, and whose outermost layer is an iron-based metal When spot-welding, or when spot-welding this multi-layer steel sheet and iron-based metal, by limiting the welding current range, without forming a brittle intermetallic compound in the weld zone Welding method of multi-layer steel sheet characterized by firmly welding multi-layer steel sheet and iron-based metal (2) Two-layer multi-layer steel sheet formed by laminating aluminum-based metal layer and iron-based metal layer When spot-welding, or when spot-welding this multi-layer steel sheet and iron-based metal or aluminum-based metal, spot welding is performed by combining only similar materials, and by limiting the welding current range, Fragile metal A multilayered steel plates or the multilayered steel and iron-based metal or aluminum-based metal without the formation of compounds in the welding method of the multilayered steel sheet characterized by firmly welded.

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a conceptual diagram showing a state in which Fe / Al / Fe three-layer multi-layer steel sheets according to the present invention are spot-welded to each other.
As shown in FIG. 1, a multi-layered steel plate composed of an iron layer 1 and an aluminum layer 2 is spot-welded using electrodes 3 while applying a pressing force. Reference numeral 4 is a welded portion. Figure 2
FIG. 4 is a conceptual diagram showing another embodiment of the present invention. As shown in FIG. 2, a state in which a three-layer multi-layer steel sheet and a cold-rolled steel sheet 5 are spot-welded using the electrode 3 while applying a pressing force is shown. As a result, spot welding could be performed without forming an intermetallic compound in the weld zone 4.

FIG. 3 is a conceptual diagram showing another embodiment of the present invention. As shown in FIG. 3, it is a diagram showing a state in which Fe / Al and a two-layer multi-layer steel sheet are spot-welded to each other.
(A) shows a state in which the Fe layers are spot-welded using the electrode 3 while applying a pressing force. As a result, spot welding could be performed without forming an intermetallic compound in the weld zone 4. FIG. 3B shows a state in which the Al layers are spot-welded using the electrodes 3 while applying a pressing force.

FIG. 4 is a conceptual diagram showing still another embodiment of the present invention. FIG. 4 is a diagram showing a case where the cold-rolled steel sheet 5 is spot-welded to the Fe side of the two-layer composite steel sheet, and FIG. It shows a state of spot welding. As a result, spot welding could be performed without forming an intermetallic compound in the weld zone 4. FIG. 4B shows a case where an Al plate 6 is welded to the Al side of a two-layer multi-layer steel plate, and the electrode 3
Shows the state of spot welding while applying pressure.

FIG. 5 is a conceptual diagram showing still another embodiment of the present invention. As shown in FIG. 5, this is an embodiment in which FIGS. 4A and 4B are integrally combined. That is, the cold-rolled steel plate 5 is spot-welded to the Fe side of the two-layer composite steel plate, and the Al plate 6 is provided with two electrodes 3 on the Al side of the two-layer composite steel plate.
3'is used for spot welding while applying pressure. As a result, it is possible to join dissimilar materials of Fe and Al without forming an intermetallic compound in the welded portions 4 and 4 '.

FIG. 6 is a conceptual diagram showing still another embodiment of the present invention. As shown in FIG. 6, a cold-rolled steel sheet is arranged on the Fe side of the two-layer composite steel sheet, and an Al plate is arranged on the Al side so that the two-layer composite steel sheet is sandwiched between them, and an electrode is used to apply pressure. Shows the state of spot welding. As a result, Fe and Al can be simultaneously bonded through the two-layer multi-layer steel sheet without forming an intermetallic compound in the welded portions 4 and 4 '. In addition, as a manufacturing method of the multilayer steel sheet used in the present invention, Fe / Al
Any method may be used as long as a method such as pressure welding at the interface and diffusion bonding is used.

[0012]

EXAMPLES The present invention will be specifically described below with reference to Examples. Example 1 Fe material is a cold-rolled steel sheet and Al material is A1050. 3
Fe (0.4) / Al (0.4) / F of 0x60mm
e (0.4) 3 layers (total thickness: 1.2 mm, where () is the thickness of each material) As shown in FIG.
F type (tip diameter: 4.5 mm diameter) electrode is used, pressing force: 2
00 kg, energizing time: 10 cyc, welding current range: 7.
When spot welding was performed under the conditions of 7 to 11.9 KA, spot welding was possible without forming an intermetallic compound in the welding current range: 7.7 to 10.0 KA. On the other hand, when the welding current value was 10.2 KA or more, a brittle intermetallic compound was formed in the welded portion, and cracking occurred.
Therefore, by limiting the welding current range to 7.7 to 10.0 KA, spot welding can be performed without forming an intermetallic compound. Even if the cold-rolled steel sheet that is an Fe material is changed to SUS304, or if A1050 that is an Al material is changed to A5050, or if the thickness ratio of each material is changed, by limiting the welding current range, It was possible to perform spot welding without forming intermetallic compounds.

Example 2 As shown in FIG. 2, a CF type (tip diameter: 4.5 m) was prepared by using the three-layer multi-layer steel sheet and the 0.8 mm cold-rolled steel sheet used in Example 1.
(m diameter) electrode, applied pressure: 200 kg, energization time: 1
When spot welding was performed under the conditions of 0 cyc and welding current range: 6.2 to 11.5 KA, welding current range: 6.2
~ 9.8 KA, without the formation of intermetallic compounds,
It was possible to perform spot welding. On the other hand, when the welding current value was 10.0 KA or more, a brittle intermetallic compound was formed in the welded portion, and cracking occurred.

Example 3 Fe material is cold rolled steel sheet, Al material is A1050 3
Fe (0.4) / Al (0.4) 2 layers of 0 × 60 mm (total thickness: 0.8 mm where the thickness of each material is in parentheses) In welding of multi-layer steel sheets, dome shape ( Tip radius: 40
R) using electrodes, applied pressure: 200 kg, energization time: 10
cyc, welding current range: 12.3 to 19.0KA, as shown in FIG. 3 (A), when Fe is combined and spot welding is performed, welding current range: 11.8 to 1
At 8.0 KA, spot welding was possible without forming intermetallic compounds. On the other hand, the welding current value is 1
At 8.2 KA or higher, a brittle intermetallic compound was formed at the weld and cracking occurred. Therefore, the welding current range is 1
By limiting to 1.8 to 18.0 KA, spot welding can be performed without forming an intermetallic compound. On the other hand, as shown in FIG. 3B, when spot welding is performed by combining Al with each other, spot welding is performed without forming an intermetallic compound within the range of welding current range: 8.9 to 15.0 KA. It was possible to do. Even if the cold-rolled steel sheet that is an Fe material is changed to SUS304, or if A1050 that is an Al material is changed to A5050, or if the thickness ratio of each material is changed, by limiting the welding current range, It was possible to perform spot welding without forming intermetallic compounds.

Example 4 On the Fe side of the two-layer double-layer steel sheet used in Example 3, FIG.
As shown in, when welding a 0.8 mm cold rolled steel sheet,
Mold (tip radius: 40R) electrode is used, pressing force: 200k
g, energization time: 10 cyc, welding current range: 6.1 to 1
When spot welding was performed under the condition of 3.1 KA, it was possible to perform spot welding without forming an intermetallic compound in the welding current value range of 6.1 to 11.0 KA.

Example 5 FIG. 4B shows on the Al side of the two-layer double-layer steel sheet used in Example 3.
As shown in Fig. 1, a 1.0 mm Al plate (material: A505
When welding 2), a dome-shaped (tip radius: 40R) electrode is used, pressing force: 200 kg, energization time: 10 cyc,
Welding current range: If spot welding is performed under the conditions of 11.8 to 22.0 KA, spot welding can be performed without forming intermetallic compounds in the range of welding current value of 11.8 to 21.0 KA. Met.

Example 6 Using a dome type (tip radius: 40R) electrode, a pressure force of 200 kg was applied to the Fe side of the two-layer double-layered steel sheet used in Example 3,
Energization time: 10 cyc, welding current range: 6.1-11.
Spot welding 0.8mm cold rolled steel sheet under the condition of 0KA,
In addition, on the Al side, a pressing force of 200 kg and an energizing time of 10
Cyc, welding current range: 11.8 to 21.0 KA spot welded 1.0 mm Al plate (material: A5052), as shown in FIG. Fe and A without forming
It became possible to join different materials.

Example 7 As shown in FIG. 6, the F of the two-layer multi-layer steel sheet used in Example 3 was used.
A 0.8 mm cold-rolled steel plate is arranged on the e side, and a 1.0 mm Al plate (material: A5052) is arranged on the Al side so as to sandwich the two-layer double-layered steel plate, and a dome shape (tip (Radius: 40R) Using electrodes, pressure welding: 200 kg, energization time: 10 cyc, welding current range: 7.3 to 15.0 KA spot welding is performed to form a brittle intermetallic compound at the spot weld. Without this, Fe and Al could be simultaneously bonded through the two-layer multi-layer steel sheet.

[0019]

As described above, according to the present invention, the materials of the same kind are combined with each other and the range of the welding current value is limited, so that the formation of the brittle intermetallic compound formed in the welded portion can be suppressed. It is possible to prevent strength deterioration of the joint portion.
In addition, Fe on the Fe side of the Fe / Al two-layer double-layer steel sheet
By welding Al to the side, excellent effects such as the possibility of Fe-Al dissimilar material joining without forming a brittle intermetallic compound at the welded portion are exhibited.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a state in which Fe / Al / Fe three-layer multi-layer steel sheets according to the present invention are spot-welded to each other.

FIG. 2 is a conceptual diagram showing another embodiment of the present invention.

FIG. 3 is a conceptual diagram showing another embodiment of the present invention.

FIG. 4 is a conceptual diagram showing still another embodiment of the present invention.

FIG. 5 is a conceptual diagram showing still another embodiment of the present invention.

FIG. 6 is a conceptual diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 1 Iron layer 2 Aluminum layer 3, 3'electrode 4, 4'welded part 5 Cold rolled steel plate 6 Al plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadao Kiriyama 1 Fuji-machi, Hirohata-ku, Himeji-shi, Hyogo Shin Nippon Steel Co., Ltd. Hirohata Works

Claims (2)

[Claims] Claims: 1. When spot welding three or more multi-layer steel sheets, which are made by laminating and joining an aluminum-based metal layer and an iron-based metal layer, and the outermost layer is an iron-based metal, or this multi-layer When spot-welding a steel sheet and an iron-based metal, by limiting the welding current range, the multi-layered steel sheets can be strengthened together without forming a fragile intermetallic compound in the welded part or this multi-layered steel sheet and the iron-based metal. A method for welding a multi-layer steel sheet, which comprises welding to a sheet. 2. When spot-welding two layers of multi-layered steel sheets formed by laminating and joining an aluminum-based metal layer and an iron-based metal layer,
Or, when spot welding this multi-layer steel sheet and iron-based metal or aluminum-based metal, spot welding is performed by combining only similar materials, and by limiting the welding current range, a weak intermetallic compound in the welded part A method for welding a multi-layer steel sheet, characterized in that the multi-layer steel sheets are welded to each other or the multi-layer steel sheet and an iron-based metal or an aluminum-based metal are strongly welded to each other without forming a weld.