JP2023130366A - Aluminum joined body - Google Patents

Abstract

To provide an aluminum joined body capable of improving welding quality by preventing solidification cracks.SOLUTION: An aluminum joined body includes a first member 1 which is an aluminum wrought and a second member 2 which is an aluminum die-cast material, and has a welding part 10 where the first member 1 and the second member 2 have been welded together. A welding bead 12 of the welding part 10 includes at least one factor component that can cause a solidification crack. The concentration of the factor component in the welding bead 12 falls out of a peak concentration value of crack sensitivity, and the concentration of the factor component in the welding bead 12 of the welding part 10 is higher than the concentration of the factor component in the first member 1.SELECTED DRAWING: Figure 1

Description

The present invention relates to a joined body in which aluminum materials are joined together.

Due to the recent trend of changing materials to reduce weight, aluminum wrought materials are becoming increasingly popular. However, it is difficult to weld aluminum wrought materials. This is because hot cracks occur when aluminum wrought materials are welded. Therefore, mechanical joining methods such as fastening methods using methods such as bolts and caulking are employed as methods for joining aluminum wrought materials.

Patent Document 1 below describes welding wrought aluminum materials of the same material to each other using laser light. However, no measures have been taken to prevent solidification cracking. It is thought that solidification cracking is less likely to occur when wrought aluminum materials are laser welded using wire, but it is difficult to ensure uniform performance by welding wires of different compositions. Also, the addition of wire results in extra cost.

JP 2019-123008 Publication

An object of the present invention is to provide an aluminum joined body that can prevent solidification cracking and improve welding quality.

The aluminum joined body according to the present invention includes a first member that is a wrought aluminum material and a second member that is an aluminum die-cast material, and has a welded part where the first member and the second member are welded, and The weld bead in this section contains at least one factor contributing to solidification cracking, and the concentration of the factor component in the weld bead deviates from the peak concentration value of cracking susceptibility. Note that the concentration of the factor component is the content of the factor component, and % is weight %.

According to this configuration, the first member, which is a wrought aluminum material, and the second member, which is an aluminum die-cast material, are welded. As shown in FIG. 12, the susceptibility to solidification cracking in aluminum alloys varies greatly depending on the concentration of the component that causes solidification cracking. The vertical axis of the graph in FIG. 12 is the height of cracking susceptibility; the larger the value, the more likely solidification cracking will occur, and the smaller the value, the less likely solidification cracking will occur. The horizontal axis of the graph in FIG. 12 is the concentration of the factor component. The cracking sensitivity reaches its maximum value when the concentration of the factor component reaches a predetermined concentration value. The concentration of the factor component at that time is referred to as the peak concentration value (Cm) of the factor component. When the concentration of the factor component becomes lower than the peak concentration value or conversely becomes higher, the cracking susceptibility decreases rapidly. According to the aluminum joined body, the concentration of the factor component in the weld bead deviates from the peak concentration value. Therefore, solidification cracking due to this factor component is less likely to occur.

In particular, it is preferable that the concentration of the factor component in the weld bead deviates by 1% or more from the peak concentration value of cracking susceptibility. According to this configuration, the concentration of the factor component in the weld bead is 1% or more higher than the peak concentration value. Cracking susceptibility decreases more rapidly when the concentration of the factor component is higher than the peak concentration value than when it is lower than the peak concentration value. Therefore, if the concentration of the factor component is higher than the peak concentration value, solidification cracking due to the factor component is less likely to occur. If the concentration of the factor component deviates from the peak concentration value by 1% or more on the higher side, the cracking susceptibility is greatly reduced, and solidification cracking caused by the factor component is reliably suppressed. Further, it is easier to remove the metal at a higher value than the peak concentration value, and the welding quality improves.

Furthermore, the first member and the second member contain the factor component, the concentration of the factor component in the first member is lower than the concentration of the factor component in the second member, and the concentration of the factor component in the weld bead is lower than the concentration of the factor component in the first member. It is preferable that the concentration of the factor component is higher than that of the factor component. According to this configuration, the concentration of the factor component in the weld bead is higher than the concentration of the factor component in the first member, so the cracking susceptibility of the factor component decreases, and the solidification caused by the factor component decreases. Cracks are less likely to occur.

In particular, it is preferable that the welded portion is a lap fillet welded portion in which the first member and the second member are overlapped and welded. When the weld is a lap fillet weld, gas and impurities in the molten metal generated during welding are likely to be released into the atmosphere. Therefore, good welding quality can be obtained. Note that when the end of the first member is located at the overlap fillet weld, it is easy to irradiate the end of the first member at the overlap fillet weld with laser light. Further, when the end of the second member is located in the overlap fillet weld, the concentration of the factor component in the weld bead is likely to be increased.

Further, it is preferable that the factor component is uniformly diffused throughout the weld bead. When the factor components are dispersed in the weld bead in this way, solidification cracking becomes even more difficult to occur.

Further, it is preferable that the factor component includes silicon, and the concentration of silicon in the weld bead is 3% or more. The concentration of silicon at which the susceptibility to solidification cracking is highest, ie, the peak silicon concentration value, is between 0.6 and 0.8%. When the silicon concentration in the weld bead is 3% or more, solidification cracking is reliably prevented.

Further, the aluminum joined body is a case, and the case includes a frame as a second member and a plate as a first member, and the plate is welded to the frame so as to cover the opening of the frame. Preferably. The frame can be easily manufactured by die casting. The case can be easily manufactured by welding the plate material to the frame.

Further, the second member contains silicon as the factor component, and the concentration of silicon in the second member is preferably from 7.0% to 13.5%. If the silicon concentration in the second member is less than 7.0%, it takes time for silicon to diffuse from the second member 2 to the weld bead 12 during welding, and the component movement to the first member 1 does not work properly. Moreover, if the silicon concentration of the second member 2 exceeds 13.5%, the workability of the material after solidification decreases, making it difficult to apply it to parts.

As described above, since the concentration of the factor component in the weld bead deviates from the peak concentration value of cracking susceptibility, solidification cracking due to the factor component is prevented from occurring, and welding quality is improved.

1 shows essential parts of an aluminum joined body in an embodiment of the present invention, with (a) being a perspective view and (b) being a plan view. A cross-sectional view of the main parts of the aluminum joined body. The manufacturing method of the same aluminum joined body is shown, (a) is a sectional view, and (b) is a perspective view. FIG. 3 is a schematic diagram showing an example of the method for manufacturing the aluminum joined body, in which (a) is a perspective view and (b) is a plan view. FIG. 3 is a schematic diagram showing an example of the method for manufacturing the aluminum joined body, in which (a) is a perspective view and (b) is a plan view. FIG. 3 is a plan view schematically showing an example of the method for manufacturing the aluminum joined body. A photograph substituted for a drawing showing the welded part of the same aluminum joint. A photograph substituted for a drawing showing the welded part of the same aluminum joint. A photograph substituted for a drawing showing the welded part of the same aluminum joint. A photograph substituted for a drawing showing the welded part of the same aluminum joint. Graph showing the measurement results of silicon concentration in the weld bead of the same weld. Graph showing the relationship between factors contributing to solidification cracking and cracking susceptibility. It is a figure which shows the aluminum joined body in other embodiments of this invention, Comprising: (a) is a perspective view seen from the bottom side, (b) is a principal part sectional view. (a) and (b) are perspective views of the state before joining of the aluminum joined body in the same embodiment as seen from the bottom side. It is a figure which shows the aluminum joined body in other embodiments of this invention, Comprising: (a) is a perspective view seen from the bottom side, (b) is a principal part sectional view. (a) and (b) are perspective views of the state before joining of the aluminum joined body in the same embodiment as seen from the bottom side.

Hereinafter, an aluminum bonded body (hereinafter simply referred to as a bonded body) according to an embodiment of the present invention will be described with reference to FIGS. 1 to 12. FIG. 1(a) is a perspective view of the main parts of the joined body of this embodiment, and FIG. 1(b) is a plan view of the main parts of the joined body. Further, a cross-sectional view of the main part of the joined body is shown in FIG. The joined body includes a first member 1 and a second member 2. The first member 1 is a wrought aluminum material. Although the shape of the first member 1 is arbitrary, it is plate-shaped, for example. The aluminum wrought material is, for example, No. 5000 series or No. 6000 series. The second member 2 is an aluminum die-cast material. The aluminum die-cast material is, for example, ADC12. The shape of the second member 2 is arbitrary.

The first member 1 and the second member 2 are joined to each other by laser welding. The joined body has a welded part where the first member 1 and the second member 2 are welded. A weld bead 12 is formed at the weld. 1 and 2 show the vicinity of the welded portion. The welded portion of this embodiment is a lap fillet welded portion 10 in which the first member 1 and the second member 2 are overlapped and welded. The end portion 1a of the first member 1 or the end portion of the second member 2 may be located in the lap fillet weld portion 10. In this embodiment, the end portion 1a of the first member 1 is located at the lap fillet weld portion 10. The overlap fillet weld 10 does not penetrate the second member 2.

In FIGS. 1 and 2, the stretching direction of the end portion 1a of the first member 1 is indicated by the symbol X, and the orthogonal direction orthogonal to the stretching direction X in a plan view seen from the first member 1 side is indicated by the symbol Y. . Further, the direction in which the first member 1 and the second member 2 overlap is indicated by the symbol Z. The overlapping direction Z is a normal direction to the overlapping surface 11 of the first member 1 and the second member 2. The overlapping direction Z is, for example, the thickness direction of the first member 1 when the first member 1 is plate-shaped. The lap fillet weld 10 is formed along the end 1a of the first member 1. That is, the lap fillet welded portion 10 is formed along the stretching direction X.

The first member 1 and the second member 2 each contain aluminum and a plurality of alloy components other than aluminum. Alloy components other than aluminum include one or more components that cause solidification cracking. A factor component that causes solidification cracking is hereinafter simply referred to as a factor component. The factor component is, for example, silicon (Si) or magnesium (Mg). The concentration of the factor component in the weld bead 12 of the lap fillet weld 10 deviates from the peak concentration value of cracking susceptibility. In particular, the concentration of the factor component in the weld bead 12 is higher than the peak concentration value of cracking susceptibility. FIG. 12 is a graph showing the relationship between the concentration of factor components and cracking susceptibility in aluminum alloys. The cracking susceptibility increases sharply at the peak concentration value (Cm) and decreases rapidly when the concentration deviates from the peak concentration value. For silicon, the peak concentration value is 0.6-0.8%. For magnesium, the peak concentration value is 1-2%. When the concentration of the factor component in the weld bead 12 deviates from the peak concentration value, the cracking susceptibility to the factor component decreases rapidly, the occurrence of solidification cracking is prevented, and welding quality is improved. In particular, if the concentration of the factor component in the weld bead 12 deviates from the peak concentration value by 1% or more, the cracking susceptibility will decrease significantly, and furthermore, if the concentration of the factor component in the weld bead 12 deviates from the peak concentration value by 1% or more, If it deviates by 2% or more, the cracking susceptibility becomes extremely small, and the occurrence of solidification cracking is reliably prevented. Note that the concentration of the factor component in the weld bead 12 is an average value in the weld bead 12.

Further, it is preferable that the concentration of the factor component in the weld bead 12 is higher than the concentration of the factor component in the first member 1. The concentration of the factor component in the weld bead 12 is preferably lower than the concentration of the factor component in the second member 2. It is preferable that the factor components are dispersed throughout the weld bead 12. This is because solidification cracking is thought to occur because, during solidification, the contributing components solidify while being segregated at a certain concentration at grain boundaries.

A case where the factor component is silicon will be explained. The silicon concentration of the weld bead 12 is either lower than the peak concentration value (0.6 to 0.8%) or higher than the peak concentration value (0.6 to 0.8%). ing. Preferably, the concentration of silicon in weld bead 12 deviates upwardly from the peak concentration value. The silicon concentration of the weld bead 12 is preferably 2% or more. In particular, the silicon concentration of the weld bead 12 is preferably 3% or more.

The silicon concentration of the second member 2 is preferably 7.0% to 13.5%. If the silicon concentration in the second member 2 is less than 7.0%, it will take time for silicon to diffuse from the second member 2 to the weld bead 12 during welding, and the component transfer to the first member 1 will not work properly. . Moreover, if the silicon concentration of the second member 2 exceeds 13.5%, the workability of the material after solidification decreases, making it difficult to apply it to parts.

The silicon concentration in the first member 1 is lower than the silicon concentration in the second member 2. For example, when the first member 1 is A5052 and the second member 2 is ADC12, the silicon concentration of the first member 1 is about 0.25%, and the silicon concentration of the second member 2 is about 9. .6 to 12%. The silicon concentration of the weld bead 12 is higher than the silicon concentration of the first member 1 and lower than the silicon concentration of the second member 2. Further, it is preferable that silicon is dispersed throughout the weld bead 12. The variation in silicon concentration in the weld bead 12 is preferably 2% or less, more preferably 1% or less.

<Laser welding method>
FIG. 3 shows the first member 1 and the second member 2 before welding. As shown by the arrow L in FIG. 3A, a laser beam is irradiated toward the end 1a of the first member 1 to weld the first member 1 and the second member 2. When the laser beam is irradiated toward the end portion 1a of the first member 1, gases and impurities in the molten metal produced by welding are likely to be released into the atmosphere. Therefore, it is easy to obtain good welding quality. In particular, it is preferable to irradiate the outer edge of the surface of the first member 1 on the side opposite to the overlapping surface 11 among the end portions 1a of the first member 1 with the laser light. It is preferable that the laser light is irradiated from a direction inclined at a predetermined angle toward the second member 2 in a direction perpendicular to the overlapping direction Z. In a cross-sectional view when the first member 1 and the second member 2 are cut along the orthogonal direction Y as shown in FIG. 3A, the inclination angle θ of the laser beam with respect to the overlapping direction Z is, for example, 30 degrees.

As shown in FIGS. 4 to 6, the laser beam is moved in the first direction X1 of the first direction X1 and the second direction X2 in the stretching direction X. The first direction X1 of the stretching direction X is the traveling direction of the laser beam. The second direction X2 is the opposite direction to the first direction X2. While moving the laser beam in the first direction X1 of the stretching direction X, the end portion 1a of the first member 1 and the second member 2 are continuously welded. When moving the laser beam in the first direction X1 of the stretching direction X, it is preferable to oscillate the laser beam. For example, it is preferable to oscillate the laser beam by driving a galvanometer mirror (not shown). The manner in which the laser beam is oscillated is not necessarily limited to the method of driving a galvanometer mirror, and may be various other methods. It is preferable to oscillate the laser beam linearly in the orthogonal direction Y or to cause the laser beam to move in a circular motion.

For example, as shown in FIG. 4, it is preferable to move the laser beam in the first direction X1 of the stretching direction X while making a circular motion. In this case, the laser beam moves in the first direction X1 of the stretching direction X while drawing a spiral. The center of the circle of circular motion is located above the end 1a of the first member 1. The circular motion of the laser beam may rotate in any direction. The laser beam crosses the end 1a of the first member 1 twice in one circular motion. The first time, the laser beam crosses the end portion 1a of the first member 1 from the first member 1 toward the second member 2 on the first direction X1 side of the stretching direction X. Next, the laser beam is emitted a second time from the second member 2 toward the first member 1 on the second direction X2 side of the stretching direction X (the opposite side to the traveling direction). traverse. However, the direction of rotation of the circular motion may be opposite to that shown in FIG. As shown in FIG. 5, the laser beam may cross the end portion 1a of the first member 1 from the second member 2 toward the first member 1 on the first direction X1 side of the stretching direction X in the circular motion. Further, as shown in FIG. 6, the laser beam may be oscillated not in a circular motion but in a reciprocating motion in the orthogonal direction Y. That is, the laser beam may be oscillated linearly in the orthogonal direction Y. In this case, the laser beam traverses the end portion 1a of the first member 1 in a direction inclined with respect to the orthogonal direction Y. In addition, after moving the laser beam in the first direction X1 of the stretching direction X, it may be further moved toward the second direction X2 of the stretching direction X. That is, the laser beam may be moved only in one direction of the stretching direction X, or may be moved in two directions, or may be moved back and forth repeatedly.

FIGS. 7 and 8 show an example of an enlarged photograph of the vicinity of the lap fillet weld 10. Photographs and measurements were taken using a scanning electron microscope JSM-6060A manufactured by JEOL Ltd. The first member 1 is A5052, and the second member 2 is ADC12. The first member 1 and the second member 2 are welded by irradiating laser light toward the end portion 1a of the first member 1. The end portion 1a of the first member 1 is located in the lap fillet weld portion 10. The many small dots shown in FIG. 7 indicate the distribution of the components. In this photo, we are specifically measuring the distribution of silicon. The small dots are almost uniformly present in the weld bead 12, which indicates that silicon is dispersed in the weld bead 12. FIG. 8 is an enlarged photograph of the actual lap fillet weld 10. In FIG. 8, measurement points when measuring the distribution of silicon in the weld bead 12 are shown as squares, and the order of the measurement points is shown below with numbers. The silicon concentration was measured at each of a total of nine points. The measurement results are shown in FIG.

Moreover, enlarged photographs of other examples are shown in FIGS. 9 and 10. The first member 1 and the second member 2 are the same as those shown in FIGS. 7 and 8. However, the first member 1 and the second member 2 are welded by irradiating the end of the second member 2 with a laser beam. The end of the second member 2 is located in the lap fillet weld 10 . Similar to FIG. 8, FIG. 10 shows measurement points in the weld bead 12. The measurement results are shown in FIG.

The horizontal axis in FIG. 11 is the measurement point in FIGS. 8 and 10. In FIG. 11, what is plotted with square marks (upper: wrought material) is the measurement result of FIGS. 7 and 8. When the end portion 1a of the first member 1 is irradiated with laser light, the silicon concentration in the weld bead 12 changes in a range of about 3 to 4%. The silicon concentration in the weld bead 12 is 3% or more, which greatly exceeds the peak concentration value (0.6 to 0.8%) and is 2% or more higher than the peak concentration value. No solidification cracking occurred, and the welding condition was good.

As mentioned above, the silicon concentration of A5052 is about 0.25%, and the silicon concentration of ADC12 is about 9.6 to 12%. The silicon concentration in the weld bead 12 is higher than the silicon concentration in A5052, which is the first member 1, and lower than the silicon concentration in the ADC 12, which is the second member 2. Further, the range of variation in the silicon concentration in the weld bead 12 is as small as about 1%. Silicon is dispersed in the weld bead 12 in a less uneven manner.

Similarly, in FIG. 11, those plotted with round marks (top: die casting) are the measurement results of FIGS. 9 and 10. When the end of the second member 2 is irradiated with laser light, the silicon concentration in the weld bead 12 changes in a range of about 7% to 9%. The concentration of silicon in the weld bead 12 is 7% or more, which greatly exceeds the peak concentration value (0.6 to 0.8%) and is 6% or more higher than the peak concentration value. . The silicon concentration in the weld bead 12 is higher than the silicon concentration in A5052, which is the first member 1, and lower than the silicon concentration in the ADC 12, which is the second member 2. The range of variation in the concentration of silicon in the weld bead 12 is as small as about 2%, and silicon is dispersed in the weld bead 12 with a small bias. No solidification cracking occurred, and the welding condition was good.

As described above, the reason why the silicon concentration in the weld bead 12 is higher than the silicon concentration in the first member 1 and greatly exceeds the peak concentration value is because the silicon in the second member 2 has migrated to the weld bead 12. This is thought to be because the silicon of the second member 2 was smoothly transferred to the weld bead 12 by the laser welding method as described above. By swinging the laser light or irradiating the end 1a of the first member 1 and the end of the second member 2 with the laser light in a direction oblique to the overlapping direction Z, the interior of the molten metal can be efficiently It is thought that it is well stirred. It is thought that by efficiently stirring the inside of the molten metal, the silicon of the second member 2 smoothly transfers into the molten metal, and the concentration of silicon in the weld bead 12 increases. It is also believed that by efficiently stirring the molten metal, silicon is dispersed in the molten metal, and the silicon concentration in the weld bead 12 is made uniform. Furthermore, when the end of the second member 2 is located at the lap fillet weld 10, the silicon of the second member 2 is welded by irradiating the end of the second member 2 with laser light. It is thought that it is easy to migrate to the bead 12.

FIG. 13 shows a case as a joined body in another embodiment of the present invention from the lower surface (bottom surface) side. The case can accommodate various items. The case is, for example, one with an open top and a bottom. Although the shape of the case is arbitrary, a rectangular case in plan view is shown as an example. The case includes a frame 20 and a bottom plate 21 as a plate material. FIG. 13 shows the state of the case before joining. The frame body 20 is a second member and is made of aluminum die-cast material. The frame body 20 has a cylindrical shape, specifically a rectangular cylindrical shape, and is open at both ends. That is, the frame 20 has a cylindrical shape with the vertical direction as the axial direction. The frame body 20 has an upper opening, which is a first opening, at an upper end, which is a first end in the axial direction, and a lower opening, which is a second opening, at a lower end, which is a second end in the axial direction. It has a department. An upper flange 30 may be provided at the upper end portion toward the outside. A lower flange 31 may be provided at the lower end portion facing inward.

The bottom plate 21 is a first member and is a plate-shaped aluminum wrought material. The bottom plate 21 is welded to the lower end of the frame body 20 using a laser beam L. The bottom plate 21 is welded to the lower surface (outer surface) of the lower flange 31 of the frame body 20. The bottom plate 21 covers the lower opening of the frame 20 and closes the lower opening. However, the bottom plate 21 does not have to close the entire lower opening of the frame 20, and a part of the lower opening of the frame 20 may not be closed by the bottom plate 21 but may be left open. The end 21a of the bottom plate 21 and the lower flange 31 of the frame 20 are welded to form a lap fillet weld 22. The entire circumference of the end portion 21a of the bottom plate 21 is welded to the frame body 20. The laser beam L is irradiated onto the end portion 21a of the bottom plate 21. The laser light L is irradiated from the outside of the case. The laser beam L moves along the edge 21a of the bottom plate 21. The laser beam L circulates around the end portion 21a of the bottom plate 21. The lap fillet weld 22 is formed around the entire circumference of the end 21a of the bottom plate 21. In this embodiment, the laser beam L is irradiated from the bottom plate 21 side. That is, as shown by arrow A in FIG. 13(b), laser light L is irradiated toward the end 21a of the bottom plate 21 from the outside of the case. A lap fillet weld 22 is formed on the outer surface of the case. However, conversely, the laser light L may be irradiated from the frame body 20 side. That is, as shown by arrow B in FIG. 13(b), the laser beam L may be irradiated from inside the frame 20 toward the end 31a of the lower flange 31. In that case, lap fillet welds 22 are formed on the inner surface of the case.

FIG. 15 shows a case as a joined body in another embodiment of the present invention from the lower surface (bottom surface) side. Moreover, FIG. 16 shows the state before the case is joined. Descriptions of configurations similar to those in FIGS. 13 and 14 will be omitted. The bottom plate 21 of this embodiment is welded to the upper surface (inner surface) of the lower flange 31 of the frame body 20. The laser beam L is irradiated onto the end 31a of the lower flange 31. The laser light L is irradiated from the outside of the case. The laser beam L moves along the end 31a of the lower flange 31. The laser beam L circulates around the end 31a of the lower flange 31. The lap fillet weld 22 is formed around the entire circumference of the end 31a of the lower flange 31. In this embodiment, the laser beam L is irradiated from the lower flange 31 side. That is, as shown by arrow C in FIG. 15(b), laser light L is irradiated toward the end 31a of the lower flange 31 from the outside of the case. A lap fillet weld 22 is formed on the outer surface of the case. However, conversely, the laser light L may be irradiated from the frame body 20 side. That is, as shown by arrow D in FIG. 15(b), the laser beam L may be irradiated from inside the frame 20 toward the end 21a of the bottom plate 21. In that case, lap fillet welds 22 are formed on the inner surface of the case.

In the above embodiment, lap fillet welding is used, but the present invention is not limited to this, and can also be applied to lap welding.

1 First member 1a End portion 2 Second member 10 Lap fillet weld portion 11 Overlap surface 12 Weld bead 20 Frame (second member)
21 Bottom plate (first member, plate material)
21a End 22 Lap fillet weld 30 Upper flange 31 Lower flange 31a End

Claims (8)

Comprising a first member that is an aluminum wrought material and a second member that is an aluminum die-cast material,
The first member and the second member have a welded part,
The weld bead of the weld zone contains at least one component that causes solidification cracking,
The aluminum joint, wherein the concentration of the factor component in the weld bead deviates from the peak concentration value of cracking susceptibility. 2. The aluminum joint according to claim 1, wherein the concentration of the factor component in the weld bead deviates from a peak concentration value of cracking susceptibility by 1% or more. the first member and the second member include the factor component;
The concentration of the factor component in the first member is lower than the concentration of the factor component in the second member,
The aluminum joined body according to claim 2, wherein the concentration of the factor component in the weld bead is higher than the concentration of the factor component in the first member. The aluminum joined body according to any one of claims 1 to 3, wherein the welded portion is a lap fillet welded portion where the first member and the second member are overlapped and welded. The aluminum joined body according to any one of claims 1 to 4, wherein the factor component is homogeneously dispersed throughout the weld bead. 6. The aluminum joined body according to claim 1, wherein the factor component includes silicon, and the concentration of silicon in the weld bead is 3% or more. The aluminum joined body is a case, and the case includes a frame as a second member and a plate as a first member, and the plate is welded to the frame so as to cover the opening of the frame. The aluminum joined body according to any one of claims 1 to 6. The aluminum joined body according to claim 1, wherein the second member contains silicon as the factor component, and the concentration of silicon in the second member is from 7.0% to 13.5%.

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