JP3780706B2 - Laser welding method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser welding method for performing partial strengthening of metals, joining of dissimilar metals, and the like by using energy of a laser beam.
[0002]
[Prior art]
A conventional laser welding method for partial strengthening is as follows. A filler material in the form of powder or paste is applied to the portion of the base metal to be reinforced and irradiated with a laser beam. A conventional laser welding method for dissimilar metal joining is as follows. Dissimilar metals are overlapped, and a laser beam is irradiated from one metal side.
[0003]
[Problems to be solved by the invention]
However, in the former laser welding method, the process of making the filler material into powder or paste is complicated, there is a possibility of powder explosion, and the filler material is likely to be scattered, so it is difficult to seal with gas. There are many inconveniences such as difficulty in controlling the supply amount of filler metal, poor yield, and generation of residue. In the latter laser welding method, there is a disadvantage that the strength is reduced due to segregation at the joint.
[0004]
OBJECT OF THE INVENTION
Accordingly, an object of the present invention is to provide a laser welding method and apparatus in which the filler material is easy to manufacture and is easy to construct, and has improved strength by suppressing segregation at the joint. .
[0005]
[Means for Solving the Problems]
When the filler wire is supplied to the molten pool generated by irradiating the base material with the laser beam, the inventor has found that the filler wire and the base material are extremely uniformly mixed. The present invention has been made based on this finding.
[0006]
That is, the laser welding method according to the present invention includes a step of superposing aluminum plated steel plates to provide a base material of the aluminum plated steel plate, and irradiating a laser beam from one aluminum plated steel plate side of the superposed aluminum plated steel plates. A step of forming a molten pool by the laser beam at a portion irradiated with the laser beam, and a step of forcibly supplying an aluminum alloy filler wire from the end of the molten pool to the formed molten pool. Thus, an alloy part is formed by the filler wire and the base material .
[0007]
Even when a filler wire was placed on the base metal and irradiated with a laser beam, it was no different from normal lap welding. On the other hand, as described above, when the filler wire is forcibly supplied to the molten pool, the filler wire and the base material are uniformly mixed. The reason is considered to be that the filler wire supplied to the molten pool is very uniformly dispersed by the divergence of the vapor metal and the convection of the molten metal. The above has been clarified by the present inventor through observation of the welding phenomenon and elemental analysis of the alloy part.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic sectional view showing a first embodiment of a laser welding method according to the present invention. 1 [1] shows the time of laser beam irradiation, and FIG. 1 [2] shows the state after laser beam irradiation. Hereinafter, description will be given based on this drawing.
[0009]
The laser welding method of this embodiment irradiates the base material 10A, 10B of the aluminum-plated steel plate with the laser beam 12, and supplies the filler wire 16 made of aluminum alloy to the molten pool 14 generated thereby, so that the filler wire 16 and the base material are supplied. The alloy part 18 with 10A and 10B is formed. In addition, although not shown in figure, the part displayed as the molten pool 14 has a steam metal, a keyhole, etc.
[0010]
Aluminum plated steel plates 10A and 10B are obtained by plating aluminum 22 on the front and back surfaces of steel plate 20, respectively. However, in the drawing, the aluminum 22 is shown thick for convenience. The aluminum plated steel plates 10A and 10B are overlapped, and the laser beam 12 is irradiated from the aluminum plated steel plate 10A side. And if the filler wire 16 is supplied to the molten pool 14 produced in the irradiated part, the alloy part 18 will be formed.
[0011]
In the alloy part 18, the filler wire 16 and the base material 30 were mixed uniformly. The reason is considered that in the molten pool 14, the vapor metal of the filler wire 16 and the base material 30 diverges or the molten metal convects due to the energy of the laser beam 12, and these metals are dispersed extremely uniformly. .
[0012]
FIG. 2 is a photograph showing the result of elemental analysis of the cross section of the alloy part formed by the laser welding method of FIG. 1 using an X-ray microanalyzer. Hereinafter, description will be given based on FIG. 1 and FIG.
[0013]
The thickness of the aluminum plated steel plates 10A and 10B is 0.85 [mm]. The filler wire 16 contains magnesium in addition to aluminum. FIG. 2 [1] shows the case of aluminum, and the white portion in the figure is aluminum. As shown, the aluminum was very uniformly dispersed. Further, although not shown, magnesium was also very uniformly dispersed. FIG. 2 [2] shows the case of iron, and the white part in the figure is iron. As shown, the iron was very uniformly dispersed. According to the present embodiment, it was possible to uniformly mix an amount of aluminum, which is impossible with a normal alloying method, into the base material iron.
[0014]
FIG. 3 is a schematic cross-sectional view showing a conventional laser welding method as a comparative example of the present embodiment. 3 [1] shows the time of laser beam irradiation, and FIG. 3 [2] shows the state after laser beam irradiation. Hereinafter, description will be given based on this drawing. However, the same parts as those in FIG.
[0015]
The aluminum plated steel plates 10A and 10B are overlapped, and the laser beam 12 is irradiated from the aluminum plated steel plate 10A side. Then, the molten layer 24 is formed around the irradiated portion, and the segregation layer 26 is formed outside thereof. The segregation layer 26 is mainly composed of an aluminum plating component. However, since the molten layer 24 has many defects and the segregation layer 26 is hard and brittle, there is almost no bonding strength. Therefore, it has been conventionally considered that laser welding of an aluminized steel sheet is impossible.
[0016]
FIG. 4 is a schematic perspective view showing a second embodiment of the laser welding method according to the present invention. Hereinafter, description will be given based on this drawing.
[0017]
In the laser welding method of the present embodiment, an aluminum alloy base material 30 is irradiated with a laser beam 12 and a filler wire 34 is supplied to a molten pool 32 generated thereby, whereby an alloy portion 36 of the filler wire 34 and the base material 30 is obtained. Is formed. Both the laser beam 12 and the filler wire 34 travel in the direction of arrow 38, and the filler wire 34 is further fed in the direction of arrow 40.
[0018]
The filler wire 34 is iron, stainless steel, titanium, copper, or the like. Thereby, the alloy part 36 becomes an extremely dense and strong alloy strengthening layer in which the filler wire 34 and the base material 30 are uniformly mixed. In particular, when an aluminum alloy was used as the base material 30 and copper was used as the filler wire 34, an alloy part 36 having a hardness three times that of the base material 30 was obtained.
[0019]
For example, the wear resistance can be improved by forming an alloy reinforcing layer on the sliding portion of an engine component made of aluminum alloy using the present embodiment. Moreover, if this embodiment is applied to a cylinder block, a crankcase, a camshaft, etc., a quality alloy strengthening layer can be formed easily and in a short time.
[0020]
【The invention's effect】
According to the laser welding method of the present invention, by supplying a filler wire to a molten pool generated by irradiating a preform with a laser beam, an alloy portion in which the filler wire and the preform are mixed extremely uniformly can be formed. . Accordingly, a filler material that is easy to manufacture and easy to handle, such as filler wire, can be used, so that the construction can be facilitated. And since generation | occurrence | production of segregation etc. can be suppressed, the intensity | strength of a junction part can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a first embodiment of a laser welding method according to the present invention. 1 [1] shows the time of laser beam irradiation, and FIG. 1 [2] shows the state after laser beam irradiation.
2 is a photograph showing the result of elemental analysis of the cross section of the alloy part formed by the laser welding method of FIG. 1 using an X-ray microanalyzer. FIG. 2 [1] is aluminum and FIG. 2 is iron.
FIG. 3 is a schematic cross-sectional view showing a conventional laser welding method as a comparative example of the first embodiment. 3 [1] shows the time of laser beam irradiation, and FIG. 3 [2] shows the state after laser beam irradiation.
FIG. 4 is a schematic perspective view showing a second embodiment of the laser welding method according to the present invention.
[Explanation of symbols]
10A, 10B, 30 Base material 12 Laser beam 14 Weld pool 16, 34 Filler wire 18, 36 Alloy part

Claims (2)

A step of providing a base material of an aluminum plated steel plate by superimposing aluminum plated steel plates, a step of irradiating a laser beam from one aluminum plated steel plate side of the superposed aluminum plated steel plates, and a portion irradiated with the laser beam Forming a molten pool with the laser beam and forcibly supplying an aluminum alloy filler wire from the end of the molten pool to the formed molten pool, whereby the filler wire and the base material are used. A laser welding method characterized by forming an alloy part . 2. The laser welding method according to claim 1, wherein the filler wire is an aluminum alloy containing magnesium .

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