Aluminum joint

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

[Technical Field]

[0001] The present invention relates to a joined body in which aluminum materials are joined together. [Background technology]

[0002] With the recent trend toward lightweight materials, the use of wrought aluminum has become increasingly widespread. However, it is difficult to weld wrought aluminum because hot cracks occur when welding wrought aluminum. For this reason, mechanical joining methods, such as fastening methods using bolts or caulking, are used to join wrought aluminum.

[0003] Patent Document 1 listed below describes welding two wrought aluminum sheets made of the same material together using a laser beam. However, no measures are taken to prevent solidification cracking. It is thought that laser welding two wrought aluminum sheets together using a wire would make solidification cracking less likely to occur, but welding wires of different compositions makes it difficult to ensure uniform performance. Furthermore, adding wire incurs additional costs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-123008 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an aluminum joined body capable of preventing solidification cracking and improving weld quality. [Means for solving the problem]

[0006] An 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 portion formed by welding the first member and the second member, wherein the weld bead of the welded portion contains at least one factor that causes solidification cracking, and the concentration of the factor in the weld bead is outside the peak concentration value for crack susceptibility. Note that the concentration of the factor is the content of the factor, and % is by weight.

[0007] According to this configuration, a first member made of wrought aluminum and a second member made of die-cast aluminum are welded together. As shown in FIG. 12, the cracking susceptibility of an aluminum alloy to solidification cracking varies significantly depending on the concentration of the causative component that causes solidification cracking. The vertical axis of the graph in FIG. 12 represents the cracking susceptibility, with larger values ​​indicating a higher likelihood of solidification cracking, and smaller values ​​indicating a lower likelihood of solidification cracking. The horizontal axis of the graph in FIG. 12 represents the concentration of the causative component. The cracking susceptibility reaches its maximum when the concentration of the causative component reaches a predetermined concentration value. The concentration of the causative component at this time is referred to as the peak concentration value (Cm) of the causative component. If the concentration of the causative component becomes lower or higher than the peak concentration value, the cracking susceptibility drops sharply. According to the aluminum joined body described above, the concentration of the causative component in the weld bead is outside the peak concentration value. Therefore, solidification cracking caused by the causative component is less likely to occur.

[0008] In particular, it is preferable that the concentration of the factor component in the weld bead deviates from the peak concentration value of cracking susceptibility by 1% or more. According to this configuration, the concentration of the factor component in the weld bead is higher than the peak concentration value by 1% or more. When the concentration of the factor component is higher than the peak concentration value, cracking susceptibility decreases more rapidly than when the concentration is lower than the peak concentration value. Therefore, when the concentration of the factor component deviates from the peak concentration value by 1% or more, solidification cracking caused by the factor component is less likely to occur. Furthermore, when the concentration of the factor component deviates from the peak concentration value by 1% or more, cracking susceptibility is significantly reduced, and solidification cracking caused by the factor component is reliably suppressed. Furthermore, it is easier to deviate from the peak concentration value by a higher value than by a lower value, improving weld quality.

[0009] Furthermore, it is preferable that the first member and the second member contain the factor, the concentration of the factor in the first member being lower than the concentration of the factor in the second member, and the concentration of the factor in the weld bead being higher than the concentration of the factor in the first member. With this configuration, the concentration of the factor in the weld bead is higher than the concentration of the factor in the first member, so that the cracking sensitivity of the factor is reduced and solidification cracking caused by the factor is less likely to occur.

[0010] In particular, the weld is preferably a lap fillet weld in which a first member and a second member are overlapped and welded. When the weld is a lap fillet weld, gases and impurities generated in the molten metal during welding are likely to be released into the atmosphere. Therefore, good welding quality can be obtained. Furthermore, when the end of the first member is located in the lap fillet weld, it is easy to irradiate the end of the first member in the lap fillet weld with laser light. Furthermore, when the end of the second member is located in the lap fillet weld, it is easy to increase the concentration of the contributing components in the weld bead.

[0011] It is also preferable that the causative elements are uniformly dispersed throughout the entire weld bead. If the causative elements are dispersed throughout the weld bead in this manner, solidification cracking is even less likely to occur.

[0012] Furthermore, the factor component preferably includes silicon, and the silicon concentration in the weld bead is preferably 3% or more. The silicon concentration at which crack susceptibility to solidification cracking is highest, i.e., the peak silicon concentration value, is 0.6 to 0.8%. If the silicon concentration in the weld bead is 3% or more, solidification cracking is reliably prevented.

[0013] Furthermore, the aluminum joined body is preferably a case, the case including a frame body as the second member and a plate material as the first member, the plate material being welded to the frame body so as to cover the opening of the frame body. The frame body can be easily manufactured by die casting. The case can be easily manufactured by welding the plate material to the frame body.

[0014] The second member contains silicon as the contributing component, and the silicon concentration in the second member is preferably 7.0% to 13.5%. If the silicon concentration in the second member is less than 7.0%, it takes a long time for silicon to diffuse from the second member 2 to the weld bead 12 during welding, and the component does not transfer well to the first member 1. If the silicon concentration in the second member 2 exceeds 13.5%, the workability of the material after solidification decreases, making it difficult to apply to parts. [Effects of the Invention]

[0015] As described above, since the concentration of the factor component in the weld bead is outside the peak concentration value of cracking susceptibility, the occurrence of solidification cracking caused by the factor component is prevented, and the weld quality is improved. [Brief explanation of the drawings]

[0016] [Figure 1] 1A and 1B are perspective and plan views showing a main part of an aluminum joined body according to one embodiment of the present invention; [Figure 2] FIG. [Figure 3] 1A and 1B show a manufacturing method of the aluminum bonded body, where (a) is a cross-sectional view and (b) is a perspective view. [Figure 4] 5A and 5B are schematic diagrams showing an example of a method for producing the aluminum bonded body, in which FIG. 5A is a perspective view and FIG. 5B is a plan view. [Figure 5] 5A and 5B are schematic diagrams showing an example of a method for producing the aluminum bonded body, in which FIG. 5A is a perspective view and FIG. 5B is a plan view. [Figure 6] FIG. 3 is a plan view schematically showing an example of a method for manufacturing the aluminum bonded body. [Figure 7] A photograph in lieu of a drawing showing the welded portion of the aluminum joint. [Figure 8] A photograph in lieu of a drawing showing the welded portion of the aluminum joint. [Figure 9] A photograph in lieu of a drawing showing the welded portion of the aluminum joint. [Figure 10] A photograph in lieu of a drawing showing the welded portion of the aluminum joint. [Figure 11] 4 is a graph showing the results of measuring the silicon concentration in the weld bead of the same weld. [Figure 12] 1 is a graph showing the relationship between solidification cracking causative components and cracking susceptibility. [Figure 13] 5A and 5B are diagrams showing an aluminum joined body according to another embodiment of the present invention, in which (a) is a perspective view seen from the bottom side, and (b) is a cross-sectional view of a main part. [Figure 14] 4A and 4B are perspective views of the aluminum joined body in the embodiment before joining, as viewed from the bottom side. [Figure 15] 5A and 5B are diagrams showing an aluminum joined body according to another embodiment of the present invention, in which (a) is a perspective view seen from the bottom side, and (b) is a cross-sectional view of a main part. [Figure 16] 4A and 4B are perspective views of the aluminum joined body in the embodiment before joining, as viewed from the bottom side. DETAILED DESCRIPTION OF THE INVENTION

[0017] An aluminum joined body (hereinafter simply referred to as a joined body) according to one embodiment of the present invention will be described below with reference to FIGS. 1 to 12. FIG. 1(a) shows a perspective view of a main part of the joined body of this embodiment, and FIG. 1(b) shows a plan view of the main part of the joined body. FIG. 2 shows a cross-sectional view of the main part of the joined body. The joined body includes a first member 1 and a second member 2. The first member 1 is an aluminum wrought material. The first member 1 may have any shape, for example, a plate shape. The aluminum wrought material may be, for example, a 5000 series or 6000 series aluminum. The second member 2 is an aluminum die-cast material. The aluminum die-cast material may be, for example, ADC12. The second member 2 may have any shape.

[0018] The first member 1 and the second member 2 are joined together by laser welding. The joined body has a weld where the first member 1 and the second member 2 are welded. A weld bead 12 is formed at the weld. Figures 1 and 2 show the vicinity of the weld. The weld in this embodiment is a lap fillet weld 10 where the first member 1 and the second member 2 are overlapped and welded. The end 1a of the first member 1 or the end of the second member 2 may be located at the lap fillet weld 10. In this embodiment, the end 1a of the first member 1 is located at the lap fillet weld 10. The lap fillet weld 10 does not penetrate the second member 2.

[0019] 1 and 2, the extension direction of the end portion 1a of the first member 1 is indicated by the symbol X, and the perpendicular direction perpendicular to the extension direction X in a plan view seen from the first member 1 side is indicated by the symbol Y. The overlapping direction of the first member 1 and the second member 2 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. For example, if the first member 1 is plate-shaped, the overlapping direction Z is the plate thickness direction of the first member 1. The lap fillet weld 10 is formed along the end portion 1a of the first member 1. That is, the lap fillet weld 10 is formed along the extension direction X.

[0020] The first member 1 and the second member 2 each contain aluminum and multiple alloying elements other than aluminum. The alloying elements other than aluminum include one or more elements that cause solidification cracking. Hereinafter, the element that causes solidification cracking will be simply referred to as the element. The element is, for example, silicon (Si) or magnesium (Mg). The concentration of the element in the weld bead 12 of the lap fillet weld 10 is outside the peak concentration value of cracking susceptibility. In particular, the concentration of the element in the weld bead 12 is higher than the peak concentration value of cracking susceptibility. Figure 12 shows a graph of the relationship between the concentration of the element in an aluminum alloy and cracking susceptibility. Crack susceptibility increases sharply at the peak concentration value (Cm) and drops sharply when it deviates from the peak concentration value. For silicon, the peak concentration value is 0.6 to 0.8%. For magnesium, the peak concentration value is 1 to 2%. If the concentration of the factor component in the weld bead 12 deviates from the peak concentration value, the cracking susceptibility to the factor component drops sharply, preventing solidification cracking and improving weld quality. 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 drops significantly. Furthermore, if the concentration of the factor component in the weld bead 12 deviates from the peak concentration value by 2% or more, the cracking susceptibility drops significantly, reliably preventing solidification cracking. Note that the concentration of the factor component in the weld bead 12 is the average value in the weld bead 12.

[0021] Furthermore, the concentration of the factor component in the weld bead 12 is preferably 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 component is dispersed throughout the weld bead 12. This is because it is believed that solidification cracking occurs when factor components solidify while segregating at a certain concentration at the grain boundary.

[0022] A case where the contributing component is silicon will be described. The silicon concentration in 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%). Preferably, the silicon concentration in weld bead 12 is higher than the peak concentration value. The silicon concentration in weld bead 12 is preferably 2% or higher. In particular, the silicon concentration in weld bead 12 is preferably 3% or higher.

[0023] The silicon concentration of the second component 2 is preferably 7.0% to 13.5%. If the silicon concentration of the second component 2 is less than 7.0%, it takes a long time for silicon to diffuse from the second component 2 to the weld bead 12 during welding, and the transfer of components to the first component 1 does not work well. Furthermore, if the silicon concentration of the second component 2 exceeds 13.5%, the workability of the material after solidification decreases, making it difficult to apply to parts.

[0024] The silicon concentration of the first member 1 is lower than the silicon concentration of the second member 2. For example, if the first member 1 is A5052 and the second member 2 is ADC12, the silicon concentration of the first member 1 is approximately 0.25%, and the silicon concentration of the second member 2 is approximately 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. It is also preferable that silicon is dispersed throughout the weld bead 12. The variation in the silicon concentration in the weld bead 12 is preferably 2% or less, and more preferably 1% or less.

[0025] <Laser welding method> FIG. 3 shows the first member 1 and the second member 2 before welding. As indicated by the arrow L in FIG. 3(a), 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 1a of the first member 1, gases and impurities in the molten metal produced by welding tend to be released into the atmosphere. This makes it easier to obtain good welding quality. In particular, it is preferable to irradiate the laser beam onto the outer edge of the surface of the first member 1 opposite the overlapping surface 11 of the end 1a of the first member 1. It is preferable to irradiate the laser beam from a direction inclined at a predetermined angle toward the second member 2, which is perpendicular to the overlapping direction Z. In a cross-sectional view of the first member 1 and the second member 2 cut along the perpendicular direction Y as shown in FIG. 3(a), the inclination angle θ of the laser beam with respect to the overlapping direction Z is, for example, 30 degrees.

[0026] As shown in FIGS. 4 to 6 , the laser beam is moved in the first direction X1 of the first direction X1 and second direction X2 in the stretching direction X. The first direction X1 in 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 the laser beam is moved in the first direction X1 in the stretching direction X, the end 1a of the first member 1 and the second member 2 are continuously welded. It is preferable to oscillate the laser beam when moving the laser beam in the first direction X1 in the stretching direction X. For example, it is preferable to oscillate the laser beam by driving a galvanometer mirror (not shown). The manner of oscillating the laser beam is not necessarily limited to the method of driving a galvanometer mirror, and various other methods may be used. It is preferable to oscillate the laser beam linearly in the orthogonal direction Y or to circularly move the laser beam.

[0027] For example, as shown in FIG. 4, it is preferable to move the laser beam in a circular motion in the first direction X1 of the stretching direction X. 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 the circular motion is positioned on the end 1a of the first member 1. The rotation direction of the circular motion of the laser beam may be any. The laser beam crosses the end 1a of the first member 1 twice in one circular motion. The laser beam first crosses the end 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. Subsequently, the laser beam second crosses the end 1a of the first member 1 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). However, the rotation direction of the circular motion may be opposite to that in FIG. 4. As shown in FIG. 5, the laser beam may traverse the end 1a of the first member 1 from the second member 2 toward the first member 1 on the first direction X1 side of the extension direction X in the circular motion. Also, as shown in FIG. 6, the oscillation of the laser beam may be a reciprocating motion in the perpendicular direction Y instead of a circular motion. That is, the laser beam may be oscillated linearly in the perpendicular direction Y. In this case, the laser beam traverses the end 1a of the first member 1 in a direction inclined with respect to the perpendicular direction Y. After moving the laser beam in the first direction X1 of the extension direction X, it may further move in the second direction X2 of the extension direction X. That is, the movement of the laser beam may be in only one direction in the extension direction X, or may be in two directions, or may be a repeated reciprocating motion.

[0028] Figures 7 and 8 show an example of a magnified photograph of the vicinity of a lap fillet weld 10. The photographs were taken and measured using a JEOL JSM-6060A scanning electron microscope. The first member 1 is made of A5052, and the second member 2 is made of ADC12. A laser beam was irradiated toward the end 1a of the first member 1 to weld the first member 1 and the second member 2. The end 1a of the first member 1 is located at the lap fillet weld 10. The numerous small dots in Figure 7 indicate the distribution of elements. In this photograph, the distribution of silicon was measured in particular. The small dots were distributed uniformly throughout the weld bead 12, indicating that silicon was dispersed throughout the weld bead 12. Figure 8 is a magnified photograph of an actual lap fillet weld 10. In Figure 8, measurement points used to measure the silicon distribution in the weld bead 12 are indicated by squares, with the order of the measurement points indicated by numbers below. The silicon concentration was measured at each of the nine points. The measurement results are shown in Figure 11.

[0029] 9 and 10 show enlarged photographs of other examples. The first member 1 and the second member 2 are the same as those 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 laser light. The end of the second member 2 is located at the lap fillet weld 10. As with FIG. 8, FIG. 10 shows measurement points in the weld bead 12. The measurement results are shown in FIG. 11.

[0030] The horizontal axis in Figure 11 represents the measurement points in Figures 8 and 10. In Figure 11, the square marks plotted (top: wrought material) represent the measurement results in Figures 7 and 8. When laser light was irradiated onto the end 1a of the first member 1, the silicon concentration in the weld bead 12 fluctuated within a range of approximately 3 to 4%. The silicon concentration in the weld bead 12 was 3% or higher, significantly exceeding the peak concentration value (0.6 to 0.8%) and being 2% or higher than the peak concentration value. No solidification cracking occurred, and the weld condition was good.

[0031] As described above, the silicon concentration of A5052 is approximately 0.25%, and the silicon concentration of ADC12 is approximately 9.6 to 12%. The silicon concentration in weld bead 12 is greater than the silicon concentration of A5052, which is the first member 1, but less than the silicon concentration of ADC12, which is the second member 2. Furthermore, the range of variation in the silicon concentration in weld bead 12 is small, at approximately 1%. Silicon is dispersed evenly throughout weld bead 12.

[0032] Similarly, in Figure 11, the plots indicated by circle marks (top: die-cast) represent the measurement results of Figures 9 and 10. When the end of the second member 2 was irradiated with laser light, the silicon concentration in the weld bead 12 fluctuated within a range of approximately 7-9%. The silicon concentration in the weld bead 12 was 7% or higher, significantly exceeding the peak concentration value (0.6-0.8%) and being 6% or higher than the peak concentration value. The silicon concentration in the weld bead 12 was higher than that of the A5052 of the first member 1 and lower than that of the ADC12 of the second member 2. The silicon concentration in the weld bead 12 varied only by approximately 2%, indicating that the silicon was dispersed evenly throughout the weld bead 12. No solidification cracking occurred, and the weld condition was good.

[0033] As described above, the silicon concentration in weld bead 12 is higher than that in first member 1 and significantly exceeds the peak concentration value. This is thought to be because silicon from second member 2 migrates to weld bead 12, and because the above-described laser welding method allows silicon from second member 2 to smoothly migrate to weld bead 12. It is thought that oscillating the laser beam or irradiating end 1a of first member 1 or end 1b of second member 2 with the laser beam in a direction oblique to overlapping direction Z efficiently stirs the molten metal. It is thought that efficient stirring of the molten metal allows silicon from second member 2 to smoothly migrate into the molten metal, increasing the silicon concentration in weld bead 12. It is also thought that efficient stirring of the molten metal disperses silicon within the molten metal, resulting in a uniform silicon concentration in weld bead 12. Furthermore, when the end of the second member 2 is located at the lap fillet weld 10, it is thought that irradiating the end of the second member 2 with laser light will make it easier for the silicon of the second member 2 to migrate to the weld bead 12.

[0034] FIG. 13 shows a case as a joined body according to another embodiment of the present invention from the bottom side. The case can accommodate various items. The case has, for example, an open top and a closed bottom. The case may have any shape, but a rectangular shape in plan view is shown as an example. The case includes a frame 20 and a bottom plate 21. FIG. 13 shows the state of the case before joining. The frame 20 is a second member made of aluminum die-cast material. The frame 20 is cylindrical, specifically, rectangular, with both ends open. That is, the frame 20 is cylindrical with its axis extending vertically. The frame 20 has an upper opening, which is a first opening, at its upper end, which is the first end in the axial direction, and a lower opening, which is a second opening, at its lower end, which is the second end in the axial direction. An upper flange 30 may be provided at the upper end, facing outward. A lower flange 31 may be provided at the lower end, facing inward.

[0035] The bottom plate 21 is a first member and is a plate-shaped wrought aluminum material. The bottom plate 21 is welded to the lower end of the frame body 20 by laser light 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 body 20 and closes the lower opening. However, the bottom plate 21 does not have to close the entire lower opening of the frame body 20, and a portion of the lower opening of the frame body 20 may be open and not closed by the bottom plate 21. An end 21a of the bottom plate 21 and the lower flange 31 of the frame body 20 are welded to form a lap fillet weld 22. The entire periphery of the end 21a of the bottom plate 21 is welded to the frame body 20. The laser light L is irradiated to the end 21a of the bottom plate 21. The laser light L is irradiated from outside the case. The laser light L moves along the end 21a of the bottom plate 21. The laser beam L travels around the end 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 applied from the bottom plate 21 side. That is, as shown by arrow A in FIG. 13(b), the laser beam L is applied from the outside of the case toward the end 21a of the bottom plate 21. The lap fillet weld 22 is formed on the outer surface of the case. However, conversely, the laser beam L may be applied from the frame 20 side. That is, as shown by arrow B in FIG. 13(b), the laser beam L may be applied from the inside of the frame 20 toward the end 31a of the lower flange 31. In that case, the lap fillet weld 22 is formed on the inner surface of the case.

[0036] FIG. 15 shows a case as a joined body according to another embodiment of the present invention from the lower (bottom) side. FIG. 16 shows the case in a state before joining. Descriptions of the same components as those in FIGS. 13 and 14 will be omitted. In this embodiment, the bottom plate 21 is welded to the upper surface (inner surface) of the lower flange 31 of the frame 20. Laser light L is applied to the end 31a of the lower flange 31. Laser light L is applied from the outside of the case. Laser light L travels along the end 31a of the lower flange 31. Laser light L circles the end 31a of the lower flange 31. A lap fillet weld 22 is formed around the entire circumference of the end 31a of the lower flange 31. In this embodiment, the laser light L is applied from the side of the lower flange 31. That is, as shown by arrow C in FIG. 15(b), the laser light L is applied from the outside of the case toward the end 31a of the lower flange 31. The lap fillet weld 22 is then formed on the outer surface of the case. However, conversely, the laser beam 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 the inside of the frame body 20 toward the end portion 21a of the bottom plate 21. In this case, the lap fillet weld 22 is formed on the inner surface of the case.

[0037] 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. [Explanation of symbols]

[0038] 1 First member 1a end 2 Second member 10 Lap fillet weld 11 Overlapping surface 12 Weld bead 20 Frame body (second member) 21 Bottom plate (first member, plate material) 21a End 22 Lap fillet weld 30 Upper flange 31 Lower flange 31a End

Claims

1. A method for laser welding a first member that is an aluminum wrought material and a second member that is an aluminum die-cast material, comprising: forming a weld by laser welding the first member and the second member without using a wire; The weld bead of the weld contains at least one component that causes solidification cracking, A laser welding method, wherein the concentration of the factor component in the weld bead is outside the peak concentration value of crack susceptibility.

2. 2. The laser welding method according to claim 1, wherein the molten metal is stirred to disperse the contributing components within the molten metal.

3. The first member is an aluminum wrought material, and the second member is an aluminum die-cast material. a welded portion where the first member and the second member are welded; The weld bead of the weld contains at least one component that causes solidification cracking, The concentration of the factor component in the weld bead is outside the peak concentration value of crack susceptibility, The aluminum joined body, wherein the factor component includes silicon, and the variation in silicon concentration in the weld bead is 2% or less.

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