JP2005254324A - Ultrasonic welding method of aluminum material and steel material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ultrasonic welding method of an aluminum material and a steel material, a method in which no Al-Fe based inter-metallic compound is formed in the joining boundary and in which a joined body of high joining strength can be stably obtained. <P>SOLUTION: In the ultrasonic welding method in which the aluminum material and the steel material are joined by using ultrasonic welding equipment, there is used the aluminum material having an arithmetic average height Ra of 0.79-1.59 μm in the surface roughness standard (JIS B 0601) in the joining face with the steel material. The aluminum material 1 is arranged on the side of the tip 5 directly connected to the horn of the ultrasonic welding equipment. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic joining method between an aluminum material and a steel material, which can obtain a high-strength joined body by joining aluminum or an aluminum alloy material (hereinafter collectively referred to as an aluminum material) and a steel material.

  Aluminum material is lightweight and excellent in aesthetics, and is used as a material for weight reduction of, for example, a transport aircraft. Among them, a hybrid structure in which an aluminum material is combined with a steel material having excellent strength and formability has attracted attention.

  However, when joining dissimilar metals such as an aluminum material and a steel material, it is difficult to apply various welding techniques that have been conventionally employed in joining the steel materials. For example, when resistance spot welding is applied to the joining of an aluminum material and a steel material, since the aluminum material has good conductivity, a fragile intermetallic compound is formed at the joint interface between the two materials after pressurization and energization. For this reason, there is a problem in that the joint portion between the aluminum material and the steel material is easily peeled at the interface, and sufficient joining quality cannot be obtained.

  Therefore, a method for joining these dissimilar metals by ultrasonic bonding instead of resistance spot welding has been proposed.

  That is, after applying a flux to the joint surface between the iron member and the aluminum material, the joint portion between the iron member and the aluminum member, which are different materials, for the purpose of providing sufficient rust prevention treatment without impairing the joint strength. There is a method of joining an iron member and an aluminum member, which is hot dip galvanized, ultrasonically joined by contacting the joining surface of the aluminum material to the galvanized film, and then subjecting the joined portion of both members to chromate treatment. It has been proposed (Patent Document 1, paragraphs 0010 to 0013, FIGS. 1 to 5). Also, in order to obtain the same bonding strength as the plating method without plating, the oxide film on the joint surface with the aluminum material of a member different from aluminum is acid-washed and then in a solder bath. In the same way, an ultrasonic wave is applied to form a solder layer on the joining surface. On the other hand, a solder layer is similarly formed on the joining surface of the dissimilar material of the aluminum material. There has been proposed a joining method of aluminum and a different material to be sonic joined (Patent Document 2, paragraphs 0012 to 0015 and FIGS. 1 to 5).

  Furthermore, a technique for solid-phase bonding without melting metal using ultrasonic vibration is disclosed, and the possibility of bonding between different metals is expected (Non-Patent Document 1, pages 19 to 24). In addition to these, for example, in order to improve wettability, a technique of soldering using ultrasonic vibration has been proposed.

Japanese Patent Application Laid-Open No. 2000-202643 Japanese Patent Laid-Open No. 10-071465 Light metal welding Vol. 37 (1999) No. 10

  However, the above prior art does not disclose the optimum bonding conditions for ultrasonic bonding, and there is a problem that sufficient bonding strength cannot be obtained even if bonding cannot be performed satisfactorily. .

  The present invention has been made in view of such a problem, and an aluminum material and a steel material in which an Al—Fe-based intermetallic compound is not generated at a bonding interface and a bonded body having high bonding strength can be stably obtained. An object is to provide an ultrasonic bonding method.

  The ultrasonic bonding method between an aluminum material and a steel material according to the present invention is an ultrasonic bonding method in which an aluminum material and a steel material are bonded using an ultrasonic bonding apparatus. The arithmetic mean height Ra of the roughness standard (JIS B 0601) is 0.79 to 1.59 μm.

  In this ultrasonic bonding method, it is preferable that the aluminum material is disposed on the chip side directly connected to the horn of the ultrasonic bonding apparatus, and the steel material is disposed on the anvil side facing the chip to perform ultrasonic bonding.

  According to the ultrasonic joining method of an aluminum material and a steel material according to the present invention, without using a special consumable such as a welding flux, and without generating an Al-Fe-based intermetallic compound at the joining interface, A bonded body with high bonding strength can be obtained by strongly bonding an aluminum material and a steel material, which are different materials. Further, in this ultrasonic bonding method, the energy required for bonding can be saved by arranging and bonding the aluminum material on the chip side directly connected to the horn of the ultrasonic bonding apparatus.

  Hereinafter, the ultrasonic joining method of the aluminum material and steel material which concerns on embodiment of this invention is demonstrated concretely with reference to drawings. FIG. 1 is a schematic diagram showing an ultrasonic bonding method between an aluminum material and a steel material according to the present invention. The ultrasonic bonding apparatus used in the method of the present invention has an anvil 6 fixed and installed in a horizontal posture, and a chip 5 that is directly connected to a horn (not shown) and ultrasonically vibrates (S) in the horizontal direction. Yes. In this ultrasonic bonding apparatus, two types of members to be bonded are sandwiched between the chip 5 and the anvil 6 and pressurized, and an ultrasonic wave is applied to this to vibrate in the S direction in FIG.

  In the apparatus having such a configuration, the aluminum material 3 and the steel material 1 are joined at the joining surface to form a joined body 4, and the joined body 4 is disposed between the tip 5 and the anvil 6. At this time, the aluminum material 3 having an arithmetic average height Ra of 0.79 to 1.59 μm in the surface roughness standard (JIS B 0601) at the joint surface with the steel material 1 is used.

  As shown in FIG. 2, the arithmetic average height Ra in the surface roughness standard (JIS B 0601) is extracted from the roughness curve by a reference length in the direction of the average line, and X in the direction of the extracted portion. When the Y axis is expressed by the following formula 1 in the direction of the axis and the vertical magnification, it is a value obtained by the following formula 2.

  By setting the arithmetic average height Ra to 0.79 to 1.59 μm, the surface of the aluminum material 3 is locally plastically deformed, so that the surface oxide film is destroyed and more active metal surfaces can be in contact with each other. Become. For this reason, the diffusion between the new metal surfaces in the initial stage of ultrasonic bonding is promoted, and the bonding strength is increased.

  When the arithmetic average height Ra is less than 0.79 μm, local plastic deformation is unlikely to occur, and the surface oxide film of the aluminum material 3 is not destroyed, so that it is not possible to promote diffusion between new metal surfaces in the initial stage of bonding. Sufficient bonding strength cannot be obtained. On the other hand, if the arithmetic average height Ra exceeds 1.59 μm, the frictional resistance increases, so that a larger amount of vibration energy than necessary is required for joining.

  At this time, it is preferable to arrange the aluminum material 3 on the chip 5 side directly connected to the horn (not shown) of the ultrasonic bonding apparatus. As a result, the aluminum material 3 is weighed as compared with the steel material 1, so that the inertial force that becomes resistance during vibration is reduced, and the joining energy is reduced.

  A vertical pressure P is applied to the bonding surface between the aluminum material 3 and the steel material 1 via the chip 5 with respect to the laminated body 4 disposed between the chip 5 and the anvil 6, and the chip 5 is moved in the horizontal direction. Ultrasonic vibration (S) is performed to vibrate the aluminum material 3 together with the chip 5 with high vibration acceleration. Heat is generated by the frictional force between the aluminum material 3 that is ultrasonically vibrated and the steel material 1 fixed to the anvil 6, atomic movement is promoted at the joining interface, and diffusion of Fe atoms in the steel material 1 to the aluminum material 3 is promoted. Arise. As a result, the aluminum material 3 and the steel material 1 are solid-phase bonded at the bonding interface.

  According to the ultrasonic joining method of the aluminum material and the steel material according to the present embodiment, the arithmetic average height Ra of the surface roughness standard (JIS B 0601) at the joining surface of the aluminum material 3 to the steel material 1 is 0.79 to 0.79. By using 1.59 μm, a high-strength bonded body can be obtained by bonding the aluminum material 3 and the steel material 1, which are different materials, without using consumables such as welding flux. Further, by disposing the aluminum material 3 at the time of bonding on the chip 5 side in the ultrasonic bonding apparatus, atomic diffusion between the materials is promoted, and a bonded body with high bonding strength can be obtained with the minimum necessary energy.

  Ultrasonic bonding is a type of solid phase bonding that generates frictional heat at the bonding interface by applying stress in the direction perpendicular to the bonding interface and repeated stress due to high vibration acceleration in a direction parallel to the bonding interface. And accelerating the movement of the atoms of the material to be welded and diffusing and joining. Therefore, in order to efficiently apply ultrasonic vibration between the members, it is preferable to firmly fix the aluminum material 3 and the chip 5 as the upper member and the steel material 1 and the anvil 6 as the lower member. The chip 5 vibrates at a frequency of 20 to 40 kHz, for example. The frequency is appropriately selected depending on the material, hardness, plate pressure, joining area, required hardness, etc. of the target workpiece.

  The ultrasonic bonding apparatus used in the present embodiment is not particularly limited, and various forms having the same operational effects can be used.

  Hereinafter, the effect of the embodiment satisfying the scope of claims will be specifically described in comparison with a comparative example that is out of the scope of the present invention. The AA6022 alloy (Al-1.2 mass% Si) adjusted to the arithmetic average height (Ra) shown in Table 1 below by polishing the joining surface with the steel material using the ultrasonic bonding apparatus shown in FIG. -0.6 mass% Mg-0.5 mass% Cu-0.1 mass% Fe-0.05 mass% Mn) is used as the aluminum material, and the steel material is 0.8 mm thick. Using SPCE steel plates, the bonding materials shown in Table 1 are arranged on the chip side, the pressing force is 500 N, the vibration frequency is 20 kHz, the amplitude is 20 μm, the bonding time is 0.23 sec. Sonicated.

  Table 1 shows the joining conditions such as required vibration energy (J) and joining strength (N) in the U-joint tensile test of the obtained joined body.

  Here, the U-shaped joint tensile test conforms to the U-shaped tensile test of the spot welded joint tensile test method (JIS Z 3137), and each material end is bent into a U-shape after ultrasonic bonding. It refers to a method in which a tensile test is performed by sandwiching the chuck portion of a tensile test device, and the bonding strength refers to a tensile load per point.

  In Table 1, in Examples 1 to 3, since the arithmetic average height Ra in the surface roughness standard (JIS B 0601) is within the range of the present invention, a high strength bonded body having a bonding strength of 350 N or more is obtained. It was. On the other hand, in Comparative Examples 1 to 4, since the arithmetic average height Ra is not within the range of the present invention, it was not possible to obtain a bonded body having sufficient bonding strength.

  By specifying the arithmetic average height Ra of the surface roughness standard at the joint surface of the aluminum material with the steel material within a predetermined range, the aluminum material and the steel material can be joined with high strength without using consumables such as welding flux. The ultrasonic bonding method of the present invention that can be performed is particularly useful in the field of bonding different types of materials.

It is a schematic diagram which shows the ultrasonic bonding method of the aluminum material and steel material which concern on this invention. It is a figure which shows arithmetic mean height Ra in the surface roughness of JISB0601.

Explanation of symbols

1: Steel material 3: Aluminum material 4: Laminate 5: Tip 6: Anvil 7: Pressure 8: Ultrasonic vibration

Claims (2)

  In the ultrasonic bonding method of bonding an aluminum material and a steel material using an ultrasonic bonding apparatus, the arithmetic average height Ra of the surface roughness standard (JIS B 0601) at the bonding surface with the steel material is 0 as the aluminum material. A method of ultrasonic bonding of an aluminum material and a steel material, wherein a material having a thickness of .79 to 1.59 μm is used. The said aluminum material is arrange | positioned at the chip | tip side directly connected to the horn of the said ultrasonic bonding apparatus, The said steel material is arrange | positioned at the anvil side facing the said chip | tip, and ultrasonic bonding is carried out. Ultrasonic bonding method between aluminum and steel.

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