JP6133286B2 - MIG welded joint structure of aluminum and steel - Google Patents

Description

  The present invention relates to a MIG welded joint structure, and in particular, a joint structure obtained by superimposing an aluminum material and a steel material, which are different metal materials, and MIG welding the overlapped fillet portion where the end of the aluminum material is located. It is about.

  In recent years, from the viewpoint of protecting the global environment and saving energy, in applications such as automobiles, railway vehicles, and other transportation equipment structures, building structures, or machine parts, steel is used where rigidity is required, while weight reduction. However, where it is necessary to make an environment-friendly structure by using a so-called hybrid structure composed of an aluminum material, in order to manufacture such a structure, Joining of a steel material and an aluminum material will be needed.

  Thus, various studies have been made on joining methods of such different metal materials such as steel and aluminum, and many techniques such as a melting method and a solid phase joining method have been proposed. Specifically, Japanese Patent Application Laid-Open No. 2004-223548 is proposed for a general MIG welding method as a melting method, and Japanese Patent Application Laid-Open No. 2003 for a general FSW (friction stir welding) as a solid phase bonding method. -275766 etc. are proposed.

  Among these proposed joining methods, the MIG welding method, which is a welding method, is the most common joining method and is well known as a relatively inexpensive joining method. As desired, it has not been easy to obtain a hybrid structure having good joint characteristics by joining steel and aluminum by such a MIG welding technique. That is, when MIG welding a steel material and an aluminum material, if the heat input by arc welding becomes too high, a brittle intermetallic compound is likely to be formed at the joint interface between them. There is a problem that cracks are likely to occur at the existence site, and conversely, if the heat input is too low, the wettability of the melt to the steel surface will deteriorate, and unbonded parts will be scattered at the joint interface. This is because there is a problem that it is difficult to obtain a good joint. For this reason, a joint interface having a joint strength that can withstand use as a structure cannot be obtained, which hinders the application of the MIG welding technique to the joining of steel and aluminum.

JP 2004-223548 A JP 2003-275876 A

  Here, the present invention has been made in the background of such circumstances, the place to be solved is a joint structure obtained by MIG welding an overlapped fillet portion of an aluminum material and a steel material, Even if there is a problem that brittle intermetallic compounds are likely to be formed at the joint interface, or there are problems of unbonded parts scattered at the joint interface, the joint strength is effectively increased, and defects such as cracks and fractures are present at the weld site. It is an object of the present invention to provide a MIG welded joint structure of an aluminum material and a steel material that does not cause the problem.

  And in order to solve the above-mentioned problems, the present inventors have conducted various studies on joint shapes obtained by MIG welding the overlapped fillet portion of an aluminum material and a steel material. As a result, an aluminum material having a predetermined alloy composition While combining steel materials, in the MIG welded joint shape obtained using a 4000 series aluminum alloy as the filler material, the joint strength is effectively improved by giving a predetermined angle to the overlapping portion of the aluminum material and the steel material. As a result of finding out the facts to be obtained and conducting further studies, the present invention has been completed.

  That is, the present invention has been completed based on such knowledge, and the gist thereof is that an aluminum material made of a 5000 series or 6000 series aluminum alloy is superimposed on a steel material, It is a joint structure obtained by MIG welding the overlapped fillet portion where the end portion is located using a filler material made of a 4000 series aluminum alloy, and the portion on the overlapping side of the steel material is made of the steel material Bending the aluminum material from the base material part to the aluminum material side at an acute angle or right angle, while bending the aluminum material part from the base material part to the steel material side at an acute angle or right angle; The MIG welding is performed in a form in which a steel material and an aluminum material are overlapped at their bent portions. That in the aluminum material and the MIG welded joint structure of the steel.

  In addition, according to one of the preferable aspects of the MIG welded joint structure of an aluminum material and a steel material according to the present invention, the bending angle of the steel material and the aluminum material is 10 ° or more and 90 ° or less, respectively. It becomes.

  Therefore, in such an MIG welded joint structure of an aluminum material and a steel material according to the present invention, the part of the steel material on the side where the aluminum material is superimposed is at an acute angle or a right angle from the base material part of the steel material to the aluminum material side. In addition to being bent, a portion of the aluminum material on the side where the steel material is overlapped is bent at an acute angle or a right angle from the base material portion of the aluminum material to the steel material side, and the steel material and the aluminum material are bent. In the overlapped form in the part, the overlap fillet where the end of the aluminum material is located is MIG welded using a predetermined filler material to form a joint structure. Even if tensile stress is applied, frictional force is effectively generated on the overlapping surface of the aluminum material and the steel material that are bent and overlapped. The tensile stress applied to the welded portion is effectively reduced, and the joint strength can be advantageously improved, and the soundness of the welded portion can be effectively improved, and cracks, fractures, etc. The occurrence of this problem can be advantageously prevented or avoided.

  And according to one of the preferable aspects of the MIG welded joint structure of an aluminum material and a steel material according to the present invention, the bending angle of the steel material and the aluminum material is configured to be 10 ° or more and 90 ° or less, respectively. The action can be exhibited more effectively, and thus it is possible to more effectively prevent the occurrence of problems such as cracks and fractures in the welded part during the tensile processing of the joint.

It is perspective explanatory drawing which shows an example of the MIG welded joint structure of the aluminum material and steel materials according to this invention. FIG. 2 is an explanatory cross-sectional view illustrating an enlarged part of the AA cross section in FIG. 1.

  Hereinafter, in order to clarify the MIG welded joint structure of an aluminum material and a steel material according to the present invention more specifically, representative embodiments of the present invention will be described in detail with reference to the drawings. .

  First, FIG. 1 and FIG. 2 schematically show an example of an MIG welded joint structure of an aluminum material and a steel material according to the present invention in the form of a perspective view and a longitudinal sectional view, respectively. In these drawings, the MIG welded joint 10 has a plate-like aluminum material 12 and a plate-like steel material 14 each having a predetermined thickness, and the aluminum material 12 is positioned above the respective end portions. In this manner, the overlapped fillet portion is MIG welded (lap fillet welded) to form a welded portion 16 so as to be integrated.

More specifically, the aluminum material 12 positioned on the upper side of the two materials to be welded stacked above and below has one flat plate-shaped end portion 20 from the base material portion 22 of the aluminum material 12. It is made into the shape bent at predetermined angle: (theta) ₁ toward the steel material 14 side to be piled up. The material of the aluminum material 12 is appropriately selected from 5000 series (Al-Mg series) or 6000 series (Al-Mg-Si series) aluminum alloys according to JIS alloy numbers. Thus, moldability and rigidity for obtaining the structure are ensured. In addition, even in the tempering of such an aluminum material 12, it is appropriately determined according to the application, but in general, when a 5000 series aluminum alloy material is used, an O material is suitable. In the case of a 6000 series aluminum alloy material, a T4 material, a T6 material, or the like is preferably used.

On the other hand, the steel material 14 positioned on the lower side of the two sheets to be overlaid is made of a material appropriately selected from various known steel materials according to characteristics required for a target joint. Here, one flat plate-like end portion 24 is bent at a predetermined angle: θ ₂ from the base material portion 26 of the steel material 14 toward the aluminum material 12 to be overlaid. It has a squeezed shape. The material of the steel material 14 is not particularly limited, and can be appropriately selected according to the characteristics required for the intended joint. For example, mild steel, carbon steel, Various known steel materials such as high-tensile steel and stainless steel can be used. In addition, such steel materials are subjected to surface treatment with conventionally known zinc or zinc alloy, aluminum or aluminum alloy, such as hot dip galvanizing (GI), alloyed hot dip galvanizing (GA), aluminum alloy plating, and electrogalvanizing. May or may not be applied. And when using a steel material that has been subjected to such a surface treatment, the presence of a surface treatment layer formed on the surface of the steel material, the arc and molten metal do not immediately contact the steel, as a result, Intrusion of the steel material is effectively prevented, and an effect that a brittle intermetallic compound layer generated by a metallurgical reaction between aluminum and steel is further hardly formed is exhibited.

The aluminum material 12 and the steel material 14 are overlapped at the end portions 20 and 24 bent in such a manner so as to have a substantially flat plate shape as a whole. That is, from the base material portion 22 of the aluminum material 12 located on the upper side to the end portion 20 which is bent and raised from the base material portion 26 of the steel material 14 located on the lower side at a predetermined angle: θ _1. The aluminum material 12 and the steel material 14 are overlapped so that the end 24 portion bent downward at a predetermined angle: θ ₂ is hooked. Further, here, the base material portion 22 of the aluminum material 12 and the base material portion 26 of the steel material 14 are positioned so as to be parallel, and the bending angles (θ ₁ , θ ₂ ) of the respective end portions 20, 24 are The angle is the same.

In addition, the bending angles (θ ₁ , θ ₂ ) of the end portions 20 and 24 that are the overlapping portions of the aluminum material 12 and the steel material 14 are preferably in the range of 10 ° to 90 °, respectively. It will be done. By setting the bending angles (θ ₁ , θ ₂ ) to values in such a range, when tensile stress is applied to the MIG welded joint 10, the bent end portions 20, In addition to the joining force of the welded part 16 formed on the part 24, it is possible to effectively generate a frictional force on the contact surfaces of the end parts 20 and 24, thereby further improving the strength of the MIG welded joint 10. It is. The lower limit of the bending angle is more preferably 15 ° or more, still more preferably 20 ° or more, and the upper limit is more preferably 70 ° or less, still more preferably 50 ° or less. It becomes. This is because if the bending angle becomes too small, the effect of improving the joint strength due to the frictional force generated in the overlapped portion will not be sufficiently exerted. It is because it becomes easy to cut | disconnect and it is not practical as a coupling.

  Then, for the end surface portion (overlapping fillet portion) of the end portion 20 of the aluminum material 12 superposed in such a manner, a MIG material made of a 4000 series aluminum alloy is used at the alloy number of JIS name. A welding operation is performed, and the end surface portion of the aluminum material 12 and the surface of the steel material 14 are melted together with the filler material, and a bead 18 made of a molten metal is formed therein, whereby the welded portion 16 is formed. Is configured. Since the 4000 series aluminum alloy used as the filler material has a relatively low melting point, it becomes easy to control the temperature of the melted portion. For this purpose, the intended welded portion 16 and thus the bead 18 are advantageous. Can be formed.

  In addition, here, as shown in FIG. 1, the aluminum material 12 and the steel material 14 are MIG welded over the entire length of the overlapped portion, and the bead 18 generated thereby causes the welded portion 16 to be Along the end face of the aluminum material 12, the aluminum material 12 is formed so as to extend continuously over the entire length. In addition, the welded portion 16 may be joined in a linearly extending manner (line joining) as shown in the figure, or may constitute a joint portion between the two materials in a spot joint that is joined at a point. . Further, as shown in FIG. 2, the welded portion 16, specifically, the bead 18, has two surfaces that are orthogonal to each other, that is, the end portion 20 and the end portion 24, that is, the end surface at the end portion 20 of the aluminum material 12 and the steel material 14. It has a substantially triangular cross-sectional shape that joins the upper surface of the end portion 24.

  Therefore, in the MIG welded joint 10 having such a structure according to the present invention, the aluminum material 12 and the steel material 14 are overlapped at the respective end portions 20 and 24 bent at a predetermined angle. Even if a tensile stress is applied to such a MIG welded joint 10, the frictional force is effectively generated in the overlapped portion, so that the tensile stress applied to the welded portion 16 is reduced, and the joint strength is advantageous. It can be improved. As a result, it is possible to advantageously prevent or avoid the possibility of occurrence of cracks, fractures, etc. in the welded part.

  The thickness of the aluminum material 12 that gives the MIG welded joint 10 according to the present invention is not particularly limited as long as it is made of a specific aluminum alloy according to the present invention. The thickness is appropriately selected according to the required characteristics, but when the MIG welded joint 10 is used for a structure, the thickness is in the range of 0.5 mm or more and 3.0 mm or less. Is appropriately selected. This is because if the plate thickness of the aluminum material 12 is less than 0.5 mm, it is difficult to ensure the rigidity of the structure, and if it exceeds 3 mm, the heat for melting the plate material is excessive during MIG welding. It is necessary for this.

  Moreover, even if it exists in the plate | board thickness of the steel material 14, it does not restrict | limit in particular, Like the plate | board thickness of the aluminum material 12, it should select suitably according to the characteristic etc. which are requested | required of the target joint. However, generally a thickness of about 0.5 mm to 3.0 mm is employed. In addition, when the plate | board thickness of the steel material 14 becomes too thick, since it will become difficult to warm a steel material, the wettability of a bead will worsen and it will become difficult to join, and when it becomes too thin, it will become difficult to ensure the steel material as a structure. It is.

  Furthermore, although the overlap allowance of the aluminum material 12 and the steel material 14 is appropriately set according to the thickness of the aluminum material 12, it is preferable that the overlap of 3 mm or more when the thickness of the aluminum material 12 is 1 mm or less. In addition, when the thickness of the aluminum material 12 exceeds 1 mm, it is preferable that the overlap length is three times longer than the thickness of the aluminum material 12. This is because if the overlap allowance is too small, the heat applied to the bead 18 is transmitted to the end surface of the steel material 14 and the heat does not escape, but becomes reflected heat and is applied to the bead 18. This is because a brittle intermetallic compound is formed thick at the joint interface, thereby reducing the joint strength.

  Further, as shown in FIG. 2, the length of the portion (end portions 20, 24) where the aluminum material 12 or the steel material 14 is bent is determined by the length of the bead 18 and the length of the overlap of the aluminum material 12 and the steel material 14. The length of the aluminum material 12 and the steel material 14 may be appropriately long in various designs so as to include the overlap margin and the length of the bead portion at one end in the length direction of each of the aluminum material 12 and the steel material 14. Will be determined. For example, it may be a length obtained by adding the length of the bead 18 and the length of the overlap, or a length obtained by adding several mm to a length obtained by adding the two.

  Furthermore, the shapes of the aluminum member 12 and the steel member 14 that provide the MIG welded joint 10 as illustrated are not limited to a flat plate shape, and the overlapping portion to which the MIG welding operation is performed is opposed to the opposite portion. As long as it can be bent at an acute angle or a right angle toward the welding material, it may be in the form of a flat plate or a face plate, and various shapes manufactured by known methods such as rolling, extrusion, forging, Both will be adopted. However, in general, a plate material, an extruded material, or an extruded shape material in which a welded portion has a flat plate shape or a face plate shape is advantageously used.

  In addition, the diameter of the filler material made of a 4000 series aluminum alloy used when MIG welding the overlapped fillet portion of the aluminum material 12 and the steel material 14 is generally in the range of 0.8 mm or more and 1.6 mm or less. Is done. This is because, if the diameter of the filler metal becomes too thin, it becomes difficult to handle, and there is a risk of hindering the MIG welding operation. If a material is used, heat at the time of melting it is required to be higher, and since the temperature of the droplets is higher, it is difficult to cool, and there is a possibility that the bonding interface between the bead 18 and the steel material 14 may be adversely affected. . In addition, as a 4000 series aluminum alloy which provides this filler material, the thing of materials, such as AA4043 and AA4047, can be mentioned, for example.

  As described above, one of the representative embodiments of the present invention has been described in detail. However, this is merely an example, and the present invention is not limited by the specific description according to such an embodiment. It should be understood that this is not to be construed as limiting. In addition, although not listed one by one, the present invention is implemented in a mode to which various changes, modifications, improvements, and the like are added based on the knowledge of those skilled in the art. It goes without saying that any one of them falls within the scope of the present invention without departing from the spirit of the invention.

  Hereinafter, representative examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited by the description of such examples. It goes without saying.

  First, in order to produce MIG welded joints of aluminum materials and steel materials in each test example, various aluminum materials, steel materials, and welding wires (filler materials) shown in Table 1 below were prepared, respectively, The combinations shown in Table 1 below were used. The thickness of each aluminum material was 1 mm, the thickness of each steel material was 0.7 mm, and the width and length of each aluminum material and steel material were both width: 20 mm and length: 100 mm. In addition, each of the aluminum material and the steel material of Test Examples 2 to 8 was bent at a bending angle: θ shown in Table 1 at a portion 15 mm from the end surface at one end portion in the length direction. It is made into a shape. Furthermore, the wire diameters of the welding wires were all 1.2 mm.

And in the combination of the aluminum material and the steel material shown in Table 1, one end in the length direction of the aluminum material is placed on one end portion in the length direction of the steel material so that the overlap margin is 7 mm. After the parts were overlapped and fixed, each MIG welding operation was performed using a general MIG welding machine, and MIG welded joints according to Test Examples 1 to 8 were manufactured. Here, the length of the bead portion (18) formed on the steel by such MIG welding operation was set to 5 mm. In Test Example 1, after the flat aluminum material was superimposed on the flat steel material in which the end portions of the aluminum material and the steel material were not bent, the end surface portion of the aluminum material and the surface of the steel material were MIG welded. Thus, a joint is obtained by bonding. Moreover, in Test Examples 2-8, as shown in FIG. 1 and FIG. 2, a combination of an aluminum material and a steel material having bent end portions is combined with the end portion (24 of the steel material (14) disposed on the lower side. ), The end portion (20) of the upper aluminum material (12) is overlapped so as to be hooked, and then the end surface portion of the end portion (20) of the aluminum material (12) and the surface of the steel material (14) are connected to MIG. A joint is obtained by welding and joining. Further, here, ₍₁ theta in Figure 2, theta ₂₎ aluminum material and the bending angle of the steel the same angle (bending angle as shown in Table 1: theta) as the base material of the aluminum material (12) (22) And the base material portion (26) of the steel material (14) are overlapped with each other. In Test Example 2, although the end portions of the aluminum material and the steel material are bent, the bending angle is relatively small, and Test Examples 3 to 8 are within the preferable range in the present invention. It has a bending angle.

  Further, as the MIG welding machine for performing such MIG welding, a precision control type MIG welding machine equipped with a welding wire of the material shown in Table 1 is used. After being connected to the welding power source device, a DC welding pulse current is passed to generate an arc between the materials to be welded to perform MIG welding, and various MIG welding according to Test Examples 1 to 8 A joint was obtained. The MIG welding conditions at that time were as follows: welding current (average current): 35 A, arc voltage (average voltage): 17 V, welding speed: 60 cm / min, shield gas (inert gas) flow rate: 15 L / min, and the welds overlapped. The MIG welding operation was performed so as to achieve line joining over the entire width of the part.

  Subsequently, each of the various MIG welded joints according to Test Examples 1 to 8 thus obtained was subjected to a tensile test. That is, the welded joint according to each test example is set in a predetermined tensile test apparatus, and a tensile force is applied in a direction perpendicular to the welded portion (weld line), so that the MIG welded joint to be tested starts to deform. The stress at the time was measured, and it was shown in Table 1 as the maximum stress.

  As is apparent from the results in Table 1, the MIG welded joints according to Test Examples 2 to 8 having the structure according to the present invention were compared with the MIG welded joint of Test Example 1 in which a flat aluminum plate and a steel plate were joined. In both cases, it can be confirmed that the stress for starting deformation is increased when a tensile stress is applied to the joint. That is, it can be confirmed that according to the MIG welded joint structured according to the present invention, the joint strength can be effectively increased.

DESCRIPTION OF SYMBOLS 10 MIG welded joint 12 Aluminum material 14 Steel material 16 Welding part 18 Bead 20 End part 22 Base material part 24 End part 26 Base material part

Claims (9)

An aluminum material made of a 5000 series or 6000 series aluminum alloy is superimposed on a steel material, and the overlapped fillet portion where the end of the aluminum material is located is welded using a filler material made of a 4000 series aluminum alloy. A joint structure obtained by
The steel material, the overlay side of the plate-shaped end portion extending from the flat portion of the base material portion of its only once acute or a right angle from the flat portion of the base metal of the steel material to the aluminum material side formed by Rukoto is bent, while having a single bending portion, wherein the aluminum material, the overlay side of the plate-shaped end portion extending from the flat portion of the base material portion of its, the from the flat portion of the base metal of the aluminum material is formed by Rukoto allowed bent only once acute or a right angle to the steel side, has a single bending portion, and the their steel and an aluminum material, they In the form in which the flat portions of the base material portion are parallel to each other and overlapped at the bent portions, the end portions of the bent portions of the aluminum material located on the inclined surfaces of the bent portions of the steel material Previous By MIG welding, MIG welded joint structure of an aluminum material and a steel material, characterized in that the weld is formed between their steel and an aluminum material.   The MIG welded joint structure of an aluminum material and a steel material according to claim 1, wherein the bending angle of the steel material and the bending angle of the aluminum material are the same angle.   The bending angle of the said steel material and the said aluminum material is 10 degrees or more and 90 degrees or less, respectively, The MIG welded joint structure of the aluminum material and steel material of Claim 1 or Claim 2 characterized by the above-mentioned.   The MIG welded joint structure of an aluminum material and a steel material according to any one of claims 1 to 3, wherein the aluminum material is an O material of a 5000 series aluminum alloy.   The MIG welded joint structure of an aluminum material and a steel material according to any one of claims 1 to 3, wherein the aluminum material is a T4 material or a T6 material of a 6000 series aluminum alloy.   The aluminum material and the steel material according to any one of claims 1 to 5, wherein the MIG welding is performed along an end surface of the aluminum material, and the aluminum material is wire-bonded to the steel material. MIG welded joint structure.   The MIG welded joint structure of an aluminum material and a steel material according to any one of claims 1 to 6, wherein the aluminum material has a thickness of 0.5 mm to 3.0 mm.   The MIG welded joint structure of an aluminum material and a steel material according to any one of claims 1 to 7, wherein the steel material has a thickness of 0.5 mm to 3.0 mm. Aluminum material made of 5000 series or 6000 series aluminum alloy is stacked on steel In addition, the overlapped fillet where the end of the aluminum material is located is the 4000 series aluminum. By performing MIG welding using a filler material made of a copper alloy, A method of manufacturing a MIG welded joint of an aluminum material and a steel material having the joint structure described in any one item Law,
The overlapping plate-like end portion extending from the flat portion of the base material portion of the steel material, Bending from the flat part of the base material part of the material to the aluminum material side at an acute angle or right angle only once, One bent portion is formed with respect to the flat portion of the base material portion of the steel material, while the flat portion of the base material portion of the steel material is formed. Said parallel to the carrier part, extending from the flat part of the base material part of the aluminum material From the flat part of the base material part of the aluminum material, the steel part Bend at an acute angle or right angle only once to the flat side of the base material of the aluminum material. Forming one bent portion, and connecting the steel material and the aluminum material to the bent portion. In the form of being overlaid on the inclined surface of the bent portion of the steel material. The MIG welding is performed on the end of the bent portion of the minium material. Manufacturing method of MIG welded joints of minium and steel.

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