JP5484253B2 - Aluminum welded structure - Google Patents

Description

  The present invention relates to an aluminum welded structure having excellent joint characteristics such as strength and bending performance after welding and excellent welding characteristics.

  In the field of automobiles and the like, aluminum materials are being applied to structures for weight reduction. In particular, the application of aluminum materials has attracted attention for the housings of battery cases of electric vehicles (EV) and hybrid vehicles (HEV) and automobile structural materials such as automobile frames.

  Such an aluminum material (aluminum or aluminum alloy) is generally rarely used as a single material, and is often welded and joined through a predetermined process such as pressing. As such a high-strength aluminum welded structure, Patent Document 1 discloses an aluminum alloy containing elements such as Si, Cu, Mg, and Mn.

JP 2000-313933 A

  However, the aluminum alloy material disclosed in Patent Document 1 does not necessarily satisfy the strength and bending characteristics required for a recent aluminum welded structure, and has problems such as cracking caused by welding. There is.

  This invention is made | formed in view of this problem, Comprising: While preventing a weld crack, it aims at providing the aluminum welded structure which has high joint performance, such as an intensity | strength and a bending, and its manufacturing method.

Engaging luer aluminum welded structure of the present invention is the aluminum welding structure obtained by melting welding using filler material with each other JIS2219 alloy material or JIS2024 alloy, the composition of the weld bead, Si: 4.0 to 5.0% by mass, Cu: 0.6 to 1.10% by mass, Mg: 0.5 to 1.5% by mass, Mn: 0.3 to 0.5% by mass, the balance Consists of Al and inevitable impurities.

  In this aluminum welded structure, the fusion welding is, for example, MIG welding.

  According to the present invention, a joint excellent in strength and bending performance is obtained, and the occurrence of cracks after welding is also suppressed.

It is a figure which shows the laser welding method. It is a figure which shows the MIG welding method. It is a figure which shows the shape of the test piece of a Fish-bone welding crack test.

Hereinafter, embodiments of the present invention will be described in detail. First, an aluminum welded structure according to the first aspect of the present invention will be described. This aluminum welded structure is obtained by melting and welding Al—Cu based alloy materials using a filler metal. In this case, for example, it can be melt welded by MIG welding. Examples of the filler material include Si: 4.7 to 5.55 mass%, Cu: 0.02 to 0.26 mass%, Mg: 0.59 to 1.66 mass%, Mn: 0.3 to A solid wire made of an aluminum alloy of 0.52% by mass, the balance Al and unavoidable impurities can be used.
The weld bead of this aluminum welded structure has Si: 4.0 to 5.0% by mass, Cu: 0.6 to 1.10% by mass, Mg: 0.5 to 1.5% by mass, Mn: 0.00%. It contains 3 to 0.5% by mass, and the balance is composed of Al and inevitable impurities. The reason for adding each component and the reason for limiting the composition are as follows. Therefore, this weld bead has high strength and excellent bending characteristics. In this aluminum alloy welded structure, for example, JIS2219 alloy or JIS2024 alloy can be used as a base material. When MIG welding is performed on the base material using the aluminum alloy as a filler material, a welding bead having the above composition can be obtained by appropriately adjusting the supply rate of the filler material.
The following describes the reason for defining the composition of this weld bead, as described above.

“Si: 4.0 to 5.0 mass%”
Si has an effect of lowering the melting point of the welded portion, but if the amount of Si in the welded portion is small, weld cracks are likely to occur. On the other hand, when there is too much Si amount, joint strength will become low and a bending characteristic will deteriorate. Therefore, the Si content of the weld bead needs to be 4.0 to 5.0 mass.

“Cu: 0.6 to 1.10 mass%”
Cu also lowers the melting point of the aluminum alloy material, but if the Cu content is low, weld cracks are likely to occur. On the other hand, when there is too much Cu content, joint strength will fall. For this reason, the Cu amount of the weld bead needs to be 0.6 to 1.10% by mass.

“Mg: 0.5 to 1.5 mass%”
If the content of Mg is too small, the strength of the weld bead is insufficient and cracks are likely to occur in the weld bead, resulting in insufficient joint strength. On the other hand, when the Mg content is too high, the joint strength is increased, but cracking is likely to occur as in the case where the content is low. For this reason, the content of Mg is 0.5 to 1.5 mass%.

“Mn: 0.3 to 0.5 mass%”
Mn has the same effect as Mg. For this reason, content of Mn shall be 0.3 thru | or 0.5 mass%.

"Inevitable impurities in weld beads"
Inevitable impurities in the weld bead include Cr, Zr, Ti, Fe, Zn, V, and the like. These are Cr ≦ 0.10 mass%, Zr ≦ 0.25 mass%, Ti ≦ 0.10 mass%. , Fe ≦ 0.5 mass%, Zn ≦ 0.25 mass%, and V ≦ 0.15 mass%, even if contained.

  In the aluminum welded structure of the present invention, the composition of the weld bead when the aluminum alloy materials are melt-welded with each other satisfies the above predetermined composition, thereby obtaining a joint having high strength and excellent bending characteristics. It is done. The aluminum alloy material itself is a so-called aluminum alloy wrought material, which is a plate material manufactured by normal rolling and an extruded material manufactured by normal extrusion.

  By having the same composition as the weld bead as the base material of the welded structure, the base material itself has high strength and excellent bending characteristics, as described in the reasons for adding each element and the reason for limiting the composition. It will be a thing. Accordingly, the welded structure also has excellent strength and bending characteristics for both the base material and the joint.

  The aluminum welded structure of the present invention may be subjected to age hardening heat treatment after solution heat treatment in the manufacturing process as appropriate.

  When the aluminum welded structure of the present invention is melt welded without using a filler metal, it can be melt welded by TIG welding or laser welding.

  Next, an aluminum welded structure according to the third aspect of the present invention will be described. This aluminum welded structure is obtained by melting and welding Al—Cu based alloy materials using a filler metal. In this case, for example, it can be melt welded by MIG welding. Examples of the filler material include Si: 4.7 to 5.55 mass%, Cu: 0.02 to 0.26 mass%, Mg: 0.59 to 1.66 mass%, Mn: 0.3 to A solid wire made of an aluminum alloy of 0.52% by mass, the balance Al and unavoidable impurities can be used.

  The weld bead of this aluminum welded structure has Si: 4.0 to 5.0% by mass, Cu: 0.6 to 1.10% by mass, Mg: 0.5 to 1.5% by mass, Mn: 0.00%. It contains 3 to 0.5% by mass, and the balance is composed of Al and inevitable impurities. The reason for adding each component and the reason for limiting the composition are as described above. Therefore, this weld bead has high strength and excellent bending characteristics. In this aluminum alloy welded structure, for example, JIS2219 alloy or JIS2024 alloy can be used as a base material. When MIG welding is performed on the base material using the aluminum alloy as a filler material, a welding bead having the above composition can be obtained by appropriately adjusting the supply rate of the filler material.

Next, the welding method will be described. FIG. 1 is a diagram showing a lap welding method by laser welding without using a filler material as a reference example . The aluminum alloy materials 2 and 3 are butted together, and the butted portion 6 is irradiated with laser light. The aluminum alloy materials 2 and 3 are heated by the laser light, and the aluminum alloy materials 2 and 3 are melt-welded. . Thereby, a butt joint is obtained.

  FIG. 2 is a view showing a butt welding method by MIG welding using a filler metal. In the case of MIG welding, the aluminum alloy materials 2 and 3 are butted together, and a welding wire 1 such as a flux-cored wire or a solid wire is fed to the butting portion 6 via a torch 7. An arc is formed between the butt 6 and the wire 1, and the butt 6 is melt welded. Thereby, a butt joint is obtained. The filler material by MIG welding is a welding wire 1.

  1 and 2, the obtained weld bead is excellent in strength and bending characteristics as described above, and the occurrence of weld cracks is prevented.

Next, the effect of the actual施例using filler metal of the present invention will be described in comparison with the comparative example. JIS2219 alloy (Cu: 5.84%, Si: 0.08%, Mg: 0.01%, Mn: 0.3%, balance Al and unavoidable impurities) and JIS2024 alloy (Cu: 4.7%, Two types of aluminum alloy plates (sheet thickness 4 mm) of Si: 0.12%, Mg: 1.44%, Mn: 0.6%, the balance Al and unavoidable impurities) were butted together and listed in Table 1 below. MIG welding was performed while adding a filler metal (diameter: 1.6 mm) having the following composition (the balance being Al and inevitable impurities). The butt portion was provided with a groove angle of 90 °. The welding conditions were as follows: current was 195 A, voltage was 23 V, welding speed was 50 cm / min, Ar gas was used as the shielding gas, and the shielding gas flow rate was 10 liters / min. According to the standard, JIS2219 alloy is Cu: 5.8 to 6.8 mass%, Si: less than 0.20 mass%, and JIS2024 alloy is Cu: 3.8 to 4.9 mass%, Si; It is less than 0.5% by mass, and all are Al—Cu based alloys having a high Cu content.

In addition, the component adjustment of the molten bead when the filler material is added is based on the component adjustment of the filler material and the dilution rate calculated from the groove shape (I type, V type, etc.) based on the component of the base material. It can be carried out. The joint thus obtained was subjected to tensile test and fishbone test. The results are shown in Table 2 below. In addition, FB is a fishbone crack, and HAZ is a weld heat affected zone crack.
First, the weld surplus was removed by grinding, a tensile test was performed with a No. 1 test piece of JIS Z3121, the weld metal part was broken, and the characteristics of the weld metal part were evaluated. The evaluation results are shown in Table 2. Moreover, as a bending test, the surplus was similarly removed by grinding from the joint, and U-shaped bending with a radius of curvature of 8 mm was performed. This radius of curvature is the radius of curvature at the center position in the thickness direction of the test piece. Further, a fish bone test was performed on the weld metal part, and the crack ratio (%) was calculated by crack ratio = crack length / weld length × 100 to evaluate weld cracks. FIG. 3 is a view showing a fishbone test piece. The case where the fishbone cracking ratio exceeds 20% was evaluated as x, and the case where it was 20% or less was evaluated as ◯. In the column of the weld heat affected zone (HAZ) crack, the cross section of the weld heat affected zone was observed. In the column of joint characteristic strength, the case of less than 300 MPa is indicated as “x” and the case of 300 MPa or more is indicated as “◯” when there is no extra height. In the bending column of the joint characteristics, when the joint was subjected to a bending test, the case where cracking occurred was indicated as x, and the case where cracking did not occur was indicated as ◯. In the comprehensive evaluation column, “◯” was given when the fishbone cracking ratio, weld heat affected zone cracking, joint strength, and joint bending test cracking were “good”, and “x” was given when any of them was x.

As shown in Table 2 , since Comparative Example 21 had a high Cu component in the molten bead, the joint strength was reduced. In Comparative Example 22, weld cracking occurred because the amount of Cu component in the molten bead was low. Since the comparative example 23 had high Si of molten bead, joint strength and the bending characteristic fell. Since Comparative Example 24 had low Si, weld cracking occurred and joint strength and bendability both decreased. Since Comparative Example 25 had high Mg, a weld crack was generated and a crack in the heat affected zone (HAZ) was also observed. In Comparative Example 26, since Mg was low, weld cracks occurred, and joint strength and bending characteristics were deteriorated. Since Comparative Example 27 had a high Mn, weld cracks occurred. Since the comparative example 28 had low Mn, joint strength fell.

  On the other hand, all of Examples 21 to 33 of the present invention did not generate weld cracks, had good joint strength and bending characteristics, and exhibited high joint performance.

1: Welding wire 2, 3: Aluminum alloy material 6: Butting part

Claims (2)

In an aluminum welded structure obtained by melt welding JIS2219 alloy material or JIS2024 alloy material using a filler metal, the composition of the weld bead is Si: 4.0 to 5.0 mass%, Cu: 0.6 to 1.10% by mass, Mg: 0.5 to 1.5% by mass, Mn: 0.3 to 0.5% by mass, the balance being made of Al and inevitable impurities Aluminum welded structure. The aluminum welded structure according to claim 1 , wherein the fusion welding is MIG welding.

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