JP2008274333A - Aluminum or aluminum alloy member for laser welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the laser weldability of the laser welding of aluminum alloy members to each other by the laser welding. <P>SOLUTION: By depositing a laser beam absorbing film 4 having a laser beam absorption ratio higher than that of aluminum, a vapor pressure lower than that of aluminum, a boiling point higher than that of aluminum, and a film thickness of ≥0.1 μm on a welding surface 3 of a base metal 2 such as aluminum alloy, the laser beam absorbing film 4 is put in a hot state higher than the boiling point of the base metal 2 by the laser welding and the laser beam absorbing film 4 sufficiently performs the heat conduction to the base metal 2, whereby the base metal such as the aluminum alloy is reliably melted, and a weld part of the high strength can be formed on the welding surface 3 of the base metal. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an aluminum or aluminum alloy (hereinafter referred to as “aluminum alloy or the like”) member that improves laser weldability by increasing the laser absorption rate in laser welding.

  Currently, many members such as aluminum alloys that are lightweight and have excellent workability are used for aircraft, vehicles, electrical and electronic equipment components, and the like. For joining the members such as the aluminum alloy, laser welding which is highly accurate and can be processed at a high speed is used. Therefore, for example, in a lithium battery used for a power source of a display unit or a motor of an electric / electronic device component, after processing a member such as a plate-like aluminum alloy into a case body, a battery member is incorporated therein, In order to seal the inside, a lid made of a member such as an aluminum alloy is joined by laser welding.

  By the way, in the above-mentioned sealed battery, in consideration of impact resistance, the case body has a relatively high strength JIS A3003 alloy (aluminum-manganese alloy) among aluminum alloy standards, and further magnesium added thereto. It has been proposed to use an aluminum alloy having higher strength (see Patent Document 1).

In the case body of the battery, the thickness is reduced for weight reduction, but it is necessary to ensure the strength of the battery as a whole. Therefore, it is required to form a high-strength joint between the case main body and the lid constituting the battery so that sufficient internal sealing can be secured. However, since members such as aluminum alloys have high laser welding reflectivity and low laser weldability, it is not easy to form a high-strength joint.
Thus, aluminum alloys have been proposed for the purpose of improving laser weldability (see Patent Documents 2 and 3). The aluminum alloy for the purpose of improving the laser weldability can improve the laser weldability and form a high-strength joint, but depending on the elements contained and the content thereof, for example, the case body of the battery or The mechanical properties required for the aluminum alloy used as the lid are deteriorated and may be lost in the worst case.

Therefore, galvanization with high laser absorptivity is applied to the weld surface of the member such as aluminum alloy so that the laser weldability can be improved without losing the mechanical properties of the aluminum alloy or the like and a high-strength joint can be formed. A layer formed is proposed (see Patent Document 4). However, since zinc contained in the galvanized layer on the welding surface of the member such as aluminum alloy has a lower boiling point than aluminum, defects such as porosity tend to occur at the joint of the member such as aluminum alloy during laser welding. Is not preferable in a sealed battery in which sealing properties are particularly required.
In addition, within the range where the mechanical properties of the member such as an aluminum alloy are not changed, an attempt is made to improve the laser weldability by adding a substance that increases the laser absorption rate in laser welding represented by the above-mentioned zinc. In aluminum alloys and the like, the substance is homogenized and cannot be concentrated on the welding surface, so it is difficult to increase the laser absorptivity and improve the laser weldability.
JP 2000-336448 A JP 2003-3226 A JP 2006-104580 A Japanese Patent Publication No. 7-65193

  The present invention makes it possible to form a high-strength joint by reliably melting the welding surface of a member such as an aluminum alloy by increasing the laser absorption rate in laser welding of the members such as an aluminum alloy.

  In order to solve the above problems, the present invention has, as a first feature, a laser absorption rate higher than that of aluminum, a vapor pressure lower than that of aluminum, and a boiling point higher than that of aluminum, on the welding surface of the base material of aluminum or aluminum alloy. In addition, a laser absorption film having a film thickness of 0.1 μm or more is formed.

As described above, by forming the laser absorption coating on the welding surface of the base material such as an aluminum alloy, the laser absorption coating absorbs the laser beam of laser welding and has a boiling point higher than that of the base aluminum alloy. It becomes high temperature. And since this laser absorption film does not evaporate immediately compared with a base material, heat conduction to this base material can fully be performed. As a result, the weld surface of the base material is reliably melted, and a high-strength joint can be formed while the laser-absorbing film piece is dissolved therein.
Furthermore, by setting the film thickness of the laser absorption coating to 0.1 μm or more, the laser absorption coating absorbs the laser beam of laser welding and becomes a high temperature not lower than the boiling point of the base aluminum alloy or the like. Since the laser absorption coating does not evaporate immediately, the high temperature state is maintained for a period of time capable of conducting heat to the base material. As a result, the weld surface of the base material is reliably melted, and a high-strength joint can be formed while the laser-absorbing film piece is dissolved therein.
If the thickness of the laser absorbing coating is less than 0.1 μm, the thickness of the laser absorbing coating is too thin to evaporate instantaneously by the heat of laser welding and maintain a high temperature state, and the base material is exposed. As a result, the laser absorption rate decreases. As a result, the weld surface of the base material does not melt sufficiently, and a high-strength joint cannot be formed. In addition, the thicker the laser absorbing film, the higher the strength of the joint is formed. However, if the thickness exceeds 20 μm, it takes time and cost to form the laser absorbing film on the weld surface of the base material, resulting in the final product. The cost-effectiveness in is not balanced. Therefore, the film thickness of the laser absorption coating is preferably 20 μm or less.

  Further, based on the first feature, the above laser absorption coating is formed of titanium, vanadium, chromium, iron, cobalt, nickel, zirconium, niobium, molybdenum, palladium, cerium, neodymium, hafnium, tantalum, tungsten, iridium, platinum. Of these, at least one kind of metal is used.

  As described above, the laser absorption coating is made of at least one of the above metals, so that the laser absorption coating absorbs the laser beam of laser welding to ensure the base material such as an aluminum alloy. Thus, the laser absorbing coating can sufficiently conduct heat to the base material. As a result, the weld surface of the base material such as an aluminum alloy is surely melted, and a high-strength joint can be formed while dissolving the laser-absorbing film piece therein.

  Further, based on the first feature and the second feature, the laser absorbing coating is formed by any one of plating, chemical conversion treatment, vapor deposition, sputtering, ion plating, and clad rolling. .

  As described above, by forming the laser absorbing film by any one of the above methods, the laser absorbing film having a necessary and uniform film thickness can be formed at a required position of the base material. For this reason, the laser absorbing film absorbs the laser beam of laser welding, so that the laser absorbing film is surely at a necessary position and uniformly becomes a high temperature not lower than the boiling point of an aluminum alloy or the like. The laser absorption coating can sufficiently conduct heat to the base material. As a result, the weld surface of the base material is reliably melted, and a high-strength joint as required can be formed at a necessary position while dissolving the laser-absorbing film piece therein.

  In the present invention, the laser absorption coating on the weld surface of the base material such as an aluminum alloy absorbs the laser beam of laser welding and becomes high temperature, and the laser absorption coating sufficiently conducts heat to the base material such as an aluminum alloy. As a result, the weld surface of the base material such as the aluminum alloy is surely melted, and a high-strength joint is formed while the laser-absorbing film piece is dissolved therein. It has the outstanding effect which can improve the weldability of welding and the quality of a final product.

Examples of the present invention will be described below.
In addition, this Example is for demonstrating one preferable embodiment of this invention, Comprising: This invention is not restrict | limited by this.

Examples of the present invention will be described.
First, in the example of the present invention, a 0.8 mm plate thickness material of JIS A1050 aluminum alloy was used as the base material 2. Then, after degreasing the welding surface 3 of the base material 2 with acetone, a laser absorbing coating 4 is formed by depositing iron or titanium while energizing the surface with 5 mA electricity in a vacuum of 0.01 torr. Sample 1 of a member such as an aluminum alloy which is an example of the above (see FIG. 1). After that, the samples 1 of the aluminum alloy member as the sample 1 were butt-joined using a YAG pulse laser having a peak output of 1.7 kw and a frequency of 120 Hz. That is, when the laser is irradiated on the welding surface 3 between the samples 1, the laser absorption coating 4 on the welding surface 3 absorbs the laser beam and becomes a high temperature state higher than the boiling point of the base material 2. 2 to conduct sufficient heat conduction. As a result, the welding surface 3 is reliably melted, and a high-strength joint 5 can be formed while the laser-absorbing film piece 4 ′ of the laser-absorbing film 4 is dissolved therein (see FIG. 2). .
Note that the strength of the joint 5 of the sample 1 is evaluated by evaluating the relative strength with the breaking strength of the joint 5 between the base materials 2 where the laser absorbing coating 4 is not formed on the weld surface 3 being 1, and the relative strength. Was 1.5 (or higher), and less than 1.5 was determined to be unacceptable (x).
As a result, as shown in Table 1, in both cases of iron and titanium, when the film thickness of the laser absorption coating 4 is 0.1 to 10 μm, the base material 2 has an increase in the film thickness of the laser absorption coating 4. It was confirmed that the penetration was deepened and the breaking strength of the joint 5 was remarkably improved. And when the film thickness of the laser absorption coating 4 exceeds 10 μm, the base material 2 melts with respect to the increase in the film thickness of the laser absorption coating 4 compared to the case where the film thickness of the laser absorption coating 4 is 0.1 to 10 μm. It was confirmed that the breaking strength of the joint portion 5 gradually improved.

  The present invention can be widely applied when performing laser welding of members such as aluminum alloys.

It is a schematic diagram from the front of members, such as an aluminum alloy which is an Example of this invention. It is a schematic diagram in the cross section at the time of laser-welding members, such as an aluminum alloy which is an Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sample 2 Base material, such as aluminum alloy 3 Welding surface 4 Laser absorption film 4 'Laser absorption film piece 5 Joint part

Claims (3)

A laser absorption film having a laser absorption rate higher than that of aluminum, a vapor pressure lower than that of aluminum, a boiling point higher than that of aluminum, and a film thickness of 0.1 μm or more is formed on the weld surface of the aluminum or aluminum alloy base material. The aluminum or aluminum alloy member for laser welding characterized by the above-mentioned. The laser absorption coating is formed from at least one metal selected from titanium, vanadium, chromium, iron, cobalt, nickel, zirconium, niobium, molybdenum, palladium, cerium, neodymium, hafnium, tantalum, tungsten, iridium, and platinum. The aluminum or aluminum alloy member for laser welding according to claim 1. 3. The laser welding aluminum or aluminum according to claim 1, wherein the laser absorbing coating is formed by any one of plating, chemical conversion, vapor deposition, sputtering, ion plating, and clad rolling. Alloy member.

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