JPH0957477A - Laser welding method for aluminum or aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the laser welding for aluminum by which the shape of a fillet weld zone of a Tee joint is stabilized and a high joining strength can be obtained. SOLUTION: A filler material 3 is supplied to an upper corner that is formed between the surface of a vertically fixed aluminum material 1 and the upper surface of a horizontally fixed aluminum material 2; and a backing material 4 provided with a notch and of copper or a copper alloy is arranged in a lower corner. This backing material is provided in its backing part with a notch with a width W1 along the surface of the aluminum material 1 and with a width W2 along the surface of the aluminum material 2, these notches W1 and W2 being assumed to satisfy equations, 0.5T<=W1 <=W2 and 0.5T<=W2 <=W1 with respect to the thickness T of the aluminum material 2. The filler material 3 arranged in the upper corner is irradiated with a laser beam by a laser generator 5 at an irradiation angle of >=60 with respect to the aluminum material 2, thereby subjecting the aluminum material through penetration to be welded to the aluminum material 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser welding method of aluminum or aluminum alloy material for laser welding a fillet welded portion of a so-called T-joint, and particularly, the shape of the welded portion is stable and good, and high welding TECHNICAL FIELD The present invention relates to a laser welding method for aluminum or aluminum alloy material capable of obtaining strength.

[0002]

2. Description of the Related Art In recent years, in automobiles, railroad cars, transportation machines for ships and the like, there has been a demand for improvement in fuel consumption and speedup, and lighter structures have been adopted. As a material for these structures, lightweight aluminum or aluminum alloy materials have come to be used in place of steel. Hereinafter, the aluminum or aluminum alloy material is generically referred to simply as the aluminum material. As a material for such a structure, a material obtained by welding an aluminum material is used, and is mainly assembled by being joined by arc welding or the like.

However, when arc welding an aluminum material, a large current is required, and the welding heat causes deformation, distortion and residual stress. Therefore,
Processing for removing these deformations, strains, and residual stresses is required, and this step is complicated, and there is a problem that the processing cost is required and the product cost is increased. Furthermore, during welding, spatter or the like may be scattered to impair the appearance of the welded portion and reduce the commercial value.

On the other hand, since the laser welding method has a high energy density, it has been widely used as a welding method for steel materials and the like as a welding method that is high speed, high efficiency and little strain. Further, since the beam diameter of the laser light is extremely small, it is possible to weld at a small fusion zone.

Recently, as described above, it has been attempted to join aluminum materials by a laser welding method in order to solve the problems in arc welding of aluminum materials.

[0006]

However, when welding aluminum materials to each other in a T-joint shape by welding by a conventional laser welding method, the leg length in the welded portion of the T-joint becomes small, so that the strength of the welded portion is reduced. There is a problem that it decreases. Therefore, in the case where the joining end portion of the second member made of the aluminum material arranged horizontally is aligned with the surface of the first member made of the aluminum material arranged vertically, and both are fillet-welded to obtain a so-called T joint, Utilizing the fact that the laser welding method can obtain a deep penetration depth,
By penetrating the second member into the first member,
A method of completely joining aluminum materials has been attempted. However, this method also has the following drawbacks.

FIG. 6 is a schematic cross-sectional view showing a welded portion of an aluminum material which has been penetration-penetrated by a laser welding method.
As shown in FIG. 6A, when the laser fillet welding is performed on the surface of the aluminum material 1 as the vertical first member so that the end portion of the aluminum material 2 as the horizontal second member becomes a T joint, Since the aluminum material has a low viscosity, the molten metal may drip at the lower portion of the welded portion 3a to form a notch.

Further, as shown in FIG. 6 (b), the molten metal may drop from the welded portion 3a of the aluminum material 1 and the aluminum material 2 to form a dent in the bead.

The present invention has been made in view of the above problems, and laser welding of aluminum or aluminum alloy material capable of forming a good beat without a notch and a dent in the welded portion and enhancing the joining strength thereof. The purpose is to provide a method.

[0010]

According to the present invention, there is provided a method for laser welding aluminum or an aluminum alloy material, comprising a first member made of aluminum or an aluminum alloy, and a second member.
The first member is substantially vertical, the second member is substantially horizontal, and its joint end is aligned with the surface of the first member; and the upper surface of the second member and the surface of the first member. In the laser welding method of aluminum or aluminum alloy material, which supplies a filler material to the upper corner portion formed between the two and laser fillet welding them, a lower surface of the second member and a surface of the first member. A backing material provided with a notch having a width W of 0.5T ≦ W ≦ 1.5T with respect to the plate thickness T of the second member is applied to the lower corner formed by Laser welding is performed by irradiating a beam to penetrate and penetrate the second member, and this backing material is preferably formed of copper or a copper alloy material.

[0011]

In the present invention, the first member is arranged vertically,
The second member is made horizontal, its joint end is aligned with the surface of the first member, and the filler is supplied to the upper corner portion formed between the upper surface of the second member and the surface of the first member. The downward welding is performed by irradiating the upper corner with laser light. This is so that the molten metal that has penetrated will flow downward due to gravity. Further, as a result, the penetrating laser light travels downward, so that the safety of the workplace, the equipment, and the welding operator can be ensured. The irradiation angle of the laser light is not particularly limited, but the irradiation angle of the laser light with respect to the second member is preferably 60 ° or more in order to prevent penetration and penetration into the back surface of the first member.

As described above, the welding of the aluminum materials so that the second member is penetrated and penetrated by the laser beam makes it difficult to form a leg length sufficient in strength by the laser welding, as described above. This is because welding is capable of obtaining a deep penetration depth, and the first member and the second member are integrated by causing the second member end portion to penetrate and penetrate.

Thus, in the present invention, a backing material made of copper or a copper alloy having a melting point higher than that of the aluminum material is applied to the lower corner portion formed by the surface of the first member and the lower surface of the second member. . When laser welding a low-viscosity aluminum material in the downward direction, as shown in FIG.
The molten metal melts down from the lower part of the member to form a dent, and the drooping of the member causes a notch, resulting in a defective bead shape and a reduction in the strength of the joint. But,
As in the present invention, by applying the backing material to the lower corner portion, it is possible to prevent the molten metal from melting and dripping, obtain a good bead shape, and obtain a high-strength joint portion.

In this case, the backing material is provided with a notch having a width W such that 0.5T≤W≤1.5T with respect to the plate thickness T of the second member. The notch width W is set to 0.5 T or more by forming a welded portion having a leg length to some extent, so that the strength can be as high as or higher than that of those joined by arc welding and high reliability can be obtained. Because. Further, when W exceeds 1.5T, the amount of heat input is increased to increase the leg length, whereby the deformation of the aluminum material and the residual stress in the joint are increased, resulting in a decrease in strength and an increase in post-treatment steps. It is not preferable.

The shape of the cutout is W ₁ along the surface of the first member and W along the surface of the second member at the lower corner formed by the surface of the first member and the lower surface of the second member. _If the widths W ₁ and W ₂ are both within the above range, it is not necessary that both have the same length.

Further, in the present invention, since the filler material such as the wire is supplied to the upper corner portion formed by the upper surface of the second member and the surface of the first member, the filler material is melted by the laser beam. Can form a ridge. The irradiation position of the laser light is not particularly limited as long as it can irradiate the filler material, but it is preferable that the laser light is irradiated so that the center of the laser light diameter passes through the center of the diameter of the filler material. As the filler material, aluminum or aluminum alloy having an arbitrary component composition can be used in consideration of strength, corrosion resistance and the like.

Regarding the shape of the aluminum material,
For example, any combination of plate material, cast material or extruded shape material can be welded by laser light.

The welding conditions for laser welding are also not particularly limited. To melt aluminum, for example, when using a carbon dioxide laser, about 3 kW, Y
When using an AG laser, it is preferable to irradiate with an output of about 2 kW or more. As described above, the welding conditions such as the laser output and the welding speed can be arbitrarily selected according to the type of laser used, the thickness and shape of the aluminum material, and the like. Although the flow rate of the shield gas differs depending on the welding conditions, it is not particularly specified, but in order to obtain a good bead shape, it is preferable to flow the shield gas in the range of about 5 to 30 liters per minute.

[0019]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 is a schematic sectional view showing a laser welding method for an aluminum material according to an embodiment of the present invention. As shown in FIG. 1, an aluminum material 1 as a first member is fixed to a fixing member 6a and arranged vertically, and an aluminum material 2 as a second member has a joining end portion of the aluminum material 1 of the aluminum material 1. Fixing member 6 according to the surface
It is fixed to b and arranged horizontally. The filler metal 3 is supplied to the upper corner portion formed between the surface of the aluminum material 1 and the upper surface of the aluminum material 2, and is formed between the surface of the aluminum material 1 and the lower surface of the aluminum material 2. A backing material 4 made of copper or a copper alloy material having a notch is installed in the lower corner portion.

FIG. 2 is a schematic sectional view showing an example of the shape of the backing material 4. As shown in FIG. 2, the backing material 4 has notches of width W ₁ along the surface of the aluminum material 1 and W ₂ along the surface of the aluminum material 1 at the lower corners of the aluminum materials 1 and 2. ing. These W ₁ and W ₂ need to be changed according to the plate thickness T of the end portion of the aluminum material 2.

The filler material 3 thus supplied to the upper corners.
When the aluminum material 2 is irradiated with laser light from the laser oscillator 5 at an irradiation angle of 60 ° or more, the aluminum material 2 is penetrated and penetrated, and the aluminum material 2 is bonded to the surface of the aluminum material 1.

FIG. 3 is an enlarged schematic sectional view showing a welded portion of an aluminum material after welding. As shown in FIG. 3, the weld metal is regulated by the notch of the backing material 4, stays in the lower corner and solidifies to form the weld 3a, and the aluminum material 2 has a good bead shape on the aluminum material 1. Are welded in the state of having. Therefore, this weld 3a
Does not have the notch and the dent generated by the conventional method.

In order to measure the strength of this welded portion, a backing material having notches of various sizes was used to prepare a test material having a welded portion of a T-joint under the welding conditions shown in Table 1 below. Then, the tensile strength of these test materials was measured.

[0024]

[Table 1]

FIG. 4 is a schematic sectional view showing a measuring method of the tensile strength test. As shown in FIG. 4, the aluminum material 1
As the first member, and the aluminum material 2 as the second member,
With respect to the test material welded to form the T joint at the welded portion 3a, both ends of the aluminum material 1 and one unwelded end of the aluminum material 2 are fixed to the fixing member 7 respectively.
After fixing with a and 7b, a tensile load was applied in the direction of the arrow shown in FIG.

FIG. 5 shows the test materials of Examples 1 and 2.
Ratio of the width W ₂ of the cutout portion to the plate thickness T of the second member (W ₂ /
FIG. 5 is a graph showing tensile strength measurement results, where T) is plotted on the vertical axis and the ratio (W ₁ / T) of the width W ₁ of the notch to the plate thickness T is plotted on the horizontal axis. In this figure, ∘ indicates that the base material ruptured in the second member, not the welded part, and x indicates that the welded part ruptured.

As shown in FIG. 5, the backing material having no notch and the ratio of the widths W ₁ and W ₂ of the notch to the plate thickness T (W ₁
/ T, W ₂ / T) was less than 0.5, the test material was welded using a backing material, and due to the insufficient leg length of the welded part, the welded part fractured and the strength was low. . In addition, the test material welded without using the backing material (shown at the origin of the figure)
The strength was reduced due to the formation of a dent or a notch due to a drooping shape due to the melt-through of the weld.

Further, a test material welded using a backing material having a ratio (W ₁ / T ₂ , W ₂ / T ₂ ) of the widths W ₁ and W ₂ of the notch to the plate thickness T of more than 1.5. Also, the strength of the welded portion decreased. It is considered that this is because the softening degree of the aluminum material and the residual stress of the test material increased due to the increase in the welding heat amount in anticipation of the increase in the volume of the notch.

On the other hand, with respect to the test material having the width of the notch within the range of the present invention, no abnormality or the like occurred in the welded portion and high strength was exhibited.

[0030]

As described in detail above, according to the method of the present invention, since aluminum members are laser-welded downward with a so-called T-joint using a backing material having a notch of a predetermined size, the welding is performed. It is possible to form a good beat without a notch and a dent in the portion, and to increase the bonding strength.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a laser welding method for an aluminum material according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of the shape of the backing material 4.

FIG. 3 is a schematic cross-sectional view showing an enlarged welded portion of an aluminum material after welding.

FIG. 4 is a schematic cross-sectional view showing a measuring method of a tensile strength test.

FIG. 5: For the test materials of Examples 1 and 2, the ratio (W ₂ / T) of the width W ₂ of the notch to the plate thickness T of the second member is plotted on the vertical axis, and the plate having the notch width W ₁ is shown. Ratio to thickness T (W ₁ /
It is a graph which shows a tensile strength measurement result by taking T) as a horizontal axis.

FIG. 6 is a schematic cross-sectional view showing a welded portion of an aluminum material that has been penetrate-penetrated by a laser welding method.

[Explanation of symbols]

 1, 2; Aluminum material 3; Filler material 3a; Welded portion 4; Backing material 5; Laser oscillator 6a, 6b, 7a, 7b; Fixing member

Claims (2)

[Claims] 1. A first member and a second member made of aluminum or an aluminum alloy, the first member being substantially vertical, the second member being substantially horizontal, and the joint end portion of the first member. Laser welding of aluminum or aluminum alloy material in which a filler metal is supplied to the upper corner portion formed between the upper surface of the second member and the surface of the first member in conformity with the surface to perform laser fillet welding of both members. In the method, 0.5T ≦ W ≦ with respect to the plate thickness T of the second member at the lower corner formed by the lower surface of the second member and the surface of the first member.
Apply a backing material with a notch with a width of 1.5 T,
A laser welding method for aluminum or an aluminum alloy, characterized in that laser welding is performed by irradiating an upper corner portion with a laser beam to penetrate and penetrate the second member. 2. The laser welding method for aluminum or aluminum alloy material according to claim 1, wherein the backing material is formed of copper or copper alloy.