Aluminum alloy material and battery temperature controller

Abstract

To provide an aluminum alloy material that can effectively suppress welding cracks. [Solution] The aluminum alloy material of this disclosure contains 4.0% by mass or more and 6.0% by mass or less of Si, 0.01% by mass or more and 1.4% by mass or less of Cu, 0.01% by mass or more and 0.7% by mass or less of Fe, 1.01% by mass or more and 2.0% by mass or less of Mn, 0.01% by mass or more and 1.5% by mass or less of Mg, 0.01% by mass or more and 0.2% by mass or less of Zn, 0.01% by mass or more and 0.2% by mass or less of Cr, 0.01% by mass or more and 0.2% by mass or less of Zr, 0.01% by mass or more and 0.2% by mass or less of Ti (titanium), 0.01% by mass or more and 0.2% by mass or less of V, and 0.001% by mass or more and 0.1% by mass or less of Sr, with the remainder being Al and unavoidable impurities.

Description

Technical Field

[0001] The present disclosure relates to an aluminum alloy material and a battery thermostat.

Background Art

[0002] Conventionally, an aluminum alloy material containing 2.6 to 5% by mass of Si, 0.2 to 1.5% by mass of Mg, 0.2 to 1.5% by mass of Zn, 0.2 to 2% by mass of Cu, 0.1 to 1.5% by mass of Fe, and further containing one or more of 0.01 to 1.0% by mass of Mn, 0.01 to 0.2% by mass of Cr, 0.01 to 0.2% by mass of Ti, 0.01 to 0.2% by mass of Zr, 0.01 to 0.2% by mass of V, with the balance being Al and inevitable impurities is known (see, for example, Patent Document 1). In this aluminum alloy material, in order to improve welding characteristics (strength and cracking properties of the welded part) while ensuring general characteristics such as strength and bending workability required for automotive materials, solid solution strengthening elements such as Fe, Cu, Mn, and precipitation hardening elements such as Cu, Mg, Zn are actively added.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in aluminum alloy materials to which Cu or Zn have been added to improve strength, the liquid and solid phases coexist during solidification of the weld, and welding cracks occur in the brittleness temperature range (BTR) where elongation (ductility) decreases significantly (see Table 1 of Patent Document 1). For this reason, when using the aluminum alloy material described in Patent Document 1 as the base material, it is necessary to perform arc welding using a wire or welding rod made of an Al alloy filler material containing 2 to 6 mass% Mg in order to suppress the occurrence of welding cracks. However, the use of wire or welding rods hinders the improvement of productivity through high-speed welding.

[0005] Therefore, the primary objective of this disclosure is to provide an aluminum alloy material that can effectively suppress welding cracks and a battery temperature controller that can improve productivity. [Means for solving the problem]

[0006] The aluminum alloy material disclosed herein contains 4.0% by mass or more and 6.0% by mass or less of Si (silicon), 0.01% by mass or more and 1.4% by mass or less of Cu (copper), 0.01% by mass or more and 0.7% by mass or less of Fe (iron), 1.01% by mass or more and 2.0% by mass or less of Mn (manganese), 0.01% by mass or more and 1.5% by mass or less of Mg (magnesium), 0.01% by mass or more and 0.2% by mass or less of Zn (zinc), 0 It contains 0.01% by mass or more and 0.2% by mass or less of Cr (chromium), 0.01% by mass or more and 0.2% by mass or less of Zr (zirconium), 0.01% by mass or more and 0.2% by mass or less of Ti (titanium), 0.01% by mass or more and 0.2% by mass or less of V (vanadium), and 0.001% by mass or more and 0.1% by mass or less of Sr (strontium), with the remainder being Al (aluminum) and unavoidable impurities.

[0007] In the aluminum alloy material of this disclosure, by setting the mass percentage composition of Si to 4.0% or more and 6.0% or less, the eutectic ratio of Al and Si can be increased, thereby further reducing the brittle temperature range. Furthermore, by including 0.001% or more and 0.1% or less of Sr in the aluminum alloy material, the Si particles that crystallize as the mass percentage composition of Si increases can be refined, making it possible to ensure good elongation (ductility) of the aluminum alloy material. In addition, by setting the mass percentage composition of Cu to 0.01% or more and 1.4% or less, the strength of the aluminum alloy material can be improved and the spontaneous potential can be nourished while suppressing the expansion of the brittle temperature range and the decrease in elongation. Furthermore, by setting the mass percentage composition of Mn to 1.01% or more and 2.0% or less, it is possible to improve the strength and elongation of the aluminum alloy material. As a result, in the aluminum alloy material of this disclosure, the brittle temperature range can be set to less than 21°C, making it possible to effectively suppress welding cracks.

[0008] The battery temperature controller of this disclosure includes two plate members formed from any of the above-mentioned aluminum alloy materials, wherein at least one of the plate members has a heat transfer medium passage formed in it and the two plate members are joined to each other by welding.

[0009] The aluminum alloy material forming the two plate members of the battery temperature controller of this disclosure is capable of effectively suppressing welding cracks. Therefore, productivity can be improved in the battery temperature controller of this disclosure by employing laser welding or the like. [Brief explanation of the drawing]

[0010] [Figure 1] This is an exploded perspective view showing the battery temperature controller of this disclosure. [Figure 2] This diagram shows the relationship between the mass percentage composition of Si and Cu and the brittle temperature range in the aluminum alloy material of this disclosure. [Modes for carrying out the invention]

[0011] Next, with reference to the drawings, embodiments for carrying out the invention of this disclosure will be described.

[0012] Figure 1 is a schematic diagram showing a battery temperature controller 10 of the present disclosure. The battery temperature controller 10 shown in the figure is applied to batteries mounted in electric vehicles such as electric vehicles and hybrid vehicles, and includes a first plate member 11 and a second plate member 12 formed from the aluminum alloy material of the present disclosure. The first plate member 11 has a plurality of rectangular openings 13 extending parallel to each other to reduce weight, and a heat transfer medium passage 15. The heat transfer medium passage 15 is a relatively shallow groove formed on the inner surface (bottom surface in Figure 1) of the portion of the first plate member 11 where the openings 13 are not formed, for example by press working, so as to be recessed from the inner surface to the outer surface (top surface in Figure 1). The second plate member 12 has a plurality of rectangular openings 14 extending parallel to each other to reduce weight, and a heat transfer medium passage 16. The heat transfer medium passage 16 is a relatively shallow groove formed on the inner surface (upper surface in Figure 1) of the portion of the second plate member 12 where the opening 14 is not formed, for example by press working, so as to be recessed from the inner surface to the outer surface (lower surface in Figure 1).

[0013] The first and second plate members 11 and 12 are overlapped so that the heat transfer medium passages 15 and 16 face each other, and are joined to each other by, for example, laser welding the inside and outside of the heat transfer medium passages 15 and 16 to prevent leakage of the heat transfer medium. This allows multiple battery cells (not shown) that constitute the battery to be arranged in the portion of the first or second plate member 11 or 12 where the openings 13 or 14 are not formed, and the temperature of each battery cell to be appropriately adjusted by circulating and supplying the heat transfer medium to the heat transfer medium passages 15 and 16. In the battery temperature controller 10, the heat transfer medium passages 15 or 16 may be formed in only one of the first or second plate members 11 or 12.

[0014] Next, the aluminum alloy material of this disclosure that forms the first and second plate members 11 and 12 described above will be described in detail.

[0015] The inventors of the present invention have diligently conducted research to suppress welding cracks in two members made of aluminum alloy material joined by welding, such as the first and second plate members 11 and 12 described above. As a result, they focused on the brittle temperature range (BTR) ΔT, in which the liquid and solid phases coexist during the solidification of the weld, and elongation (ductility) is greatly reduced. The inventors have found that in aluminum alloy materials to which Cu, Zn, etc., are added to improve strength, the occurrence of welding cracks can be substantially eliminated by setting the brittle temperature range ΔT to less than 21°C.

[0016] Based on the research results, the aluminum alloy material disclosed herein contains 4.0% by mass or more and 6.0% by mass or less of Si (silicon), 0.01% by mass or more and 1.4% by mass or less of Cu (copper), 0.01% by mass or more and 0.7% by mass or less of Fe (iron), 1.01% by mass or more and 2.0% by mass or less of Mn (manganese), 0.01% by mass or more and 1.5% by mass or less of Mg (magnesium), and 0.01% by mass or more and 0.2% by mass or less of Zn ( The alloy contains zinc, 0.01% to 0.2% by mass of chromium (Cr), 0.01% to 0.2% by mass of zirconium (Zr), 0.01% to 0.2% by mass of titanium (Ti), 0.01% to 0.2% by mass of vanadium (V), and 0.001% to 0.1% by mass of strontium (Sr), with the remainder being aluminum (Al) and unavoidable impurities. By adopting such a composition, the brittle temperature range ΔT of the aluminum alloy material can be reduced to less than 21°C.

[0017] In other words, by setting the mass percentage composition of Si in the aluminum alloy material to 4.0% or more and 6.0% or less, the eutectic ratio of Al and Si can be increased, and the brittle temperature range can be narrowed. Here, the upper limit of the mass percentage composition of solid solution Si in Al-Si binary alloys is 1.67%, and if Si exceeding this is added to the aluminum alloy material, coarse Si particles may crystallize, potentially reducing the elongation of the aluminum alloy material. Taking this into account, the aluminum alloy material of this disclosure contains Sr in an amount of 0.001% or more and 0.1% or less by mass. Sr can act as a nucleus for Si particles, and as the mass percentage composition of Si increases, it refines the Si particles that crystallize. This makes it possible to ensure good elongation of the aluminum alloy material. Furthermore, by setting the mass percentage composition of Cu to 0.01% or more and 1.4% or less by mass, it is possible to improve the strength of the aluminum alloy material and nourish the natural potential while suppressing the expansion of the brittle temperature range and the decrease in elongation (ductility). Furthermore, by setting the mass percentage composition of Mn to 1.01% by mass or more and 2.0% by mass or less, it becomes possible to improve the strength and elongation of the aluminum alloy material. As a result, the brittle temperature range ΔT of the aluminum alloy material of this disclosure can be set to less than 21°C, making it possible to effectively suppress welding cracks.

[0018] Furthermore, by setting the mass percentage composition of Si to 4.0% or more and 5.0% or less, the crystallization of coarse Si particles can be suppressed while ensuring good strength and elongation of the aluminum alloy material. In addition, by setting the mass percentage composition of Sr to 0.005% or more and 0.03% or less, the refinement of Si particles can be promoted, and the crystallization of coarse compounds mainly composed of Sr can be suppressed while further improving the elongation of the aluminum alloy material. Furthermore, by setting the mass percentage composition of Cu to 0.2% or more and 0.8% or less, and the mass percentage composition of Mn to 1.2% or more and 1.8% or less, the decrease in elongation of the aluminum alloy material can be suppressed. Accordingly, the aluminum alloy material of this disclosure preferably contains Si in an amount of 4.0% or more and 5.0% or less, Cu in an amount of 0.2% or more and 0.8% or less, Mn in an amount of 1.2% or more and 1.8% or less, and Sr in an amount of 0.005% or more and 0.03% or less.

[0019] Furthermore, by setting the mass percentage composition of Fe to 0.2 mass% or more and 0.6 mass% or less, the grain size can be refined, further improving the elongation of the aluminum alloy material. Also, by setting the mass percentage composition of Mg to 0.01 mass% or more and 0.4 mass% or less, the strength of the aluminum alloy material can be further improved through solid solution strengthening and precipitation strengthening by heat treatment while suppressing the decrease in elongation. Furthermore, by setting the mass percentage composition of Zn to 0.01 mass% or more and 0.1 mass% or less, the surface treatability of the aluminum alloy material can be improved while suppressing the expansion of the brittle temperature range ΔT and the lowering of the spontaneous potential. In addition, by setting the mass percentage composition of Cr, Zr, Ti, and V to 0.01 mass% or more and 0.1 mass% or less, the grain size can be refined, further improving the elongation and toughness of the aluminum alloy material. Accordingly, the aluminum alloy material of this disclosure preferably contains 0.2% by mass or more and 0.6% by mass or less of Fe, 0.01% by mass or more and 0.4% by mass or less of Mg, 0.01% by mass or more and 0.1% by mass or less of Zn, 0.01% by mass or more and 0.1% by mass or less of Cr, 0.01% by mass or more and 0.1% by mass or less of Zr, 0.01% by mass or more and 0.1% by mass or less of Ti, and 0.01% by mass or more and 0.1% by mass or less of V.

[0020] Furthermore, in order to keep the brittle temperature range ΔT below 21°C, it is preferable to change the mass percentage composition of Cu according to the mass percentage composition of Si in the aluminum alloy material, as shown in Figure 2. According to our analysis, when the mass percentage composition of Si is 4.00% and the mass percentage composition of Cu is 0.6%, the brittle temperature range ΔT becomes 21°C or higher, whereas when the mass percentage composition of Cu is 0.55% or less, the brittle temperature range ΔT can be kept below 21°C. Moreover, when the mass percentage composition of Si is 4.10% and the mass percentage composition of Cu is 0.8%, the brittle temperature range ΔT becomes 21°C or higher, whereas when the mass percentage composition of Cu is 0.7% or less, the brittle temperature range ΔT can be kept below 21°C. Furthermore, when the mass percentage composition of Si is 4.25-6.00%, if the mass percentage composition of Cu is 1.5%, the brittle temperature range ΔT will be 21°C or higher, whereas if the mass percentage composition of Cu is 1.4% or less, the brittle temperature range ΔT can be kept below 21°C.

[0021] Furthermore, the inventors compared the aluminum alloy material of this disclosure with Comparative Examples 1 and 2, which are commonly available aluminum alloy materials. The aluminum alloy material of this disclosure used for comparison contains 4.5 mass% Si, 0.20 mass% Cu, 0.35 mass% Fe, 1.50 mass% Mn, and 0.01 mass% Sr. The aluminum alloy material of Comparative Example 1 is an A3003 material containing 0.35 mass% Si, 0.15 mass% Cu, 0.35 mass% Fe, 0.05 mass% Zn, and 1.25 mass% Mn, but without Sr. The aluminum alloy material of Comparative Example 2 is an A3003 material containing 0.75 mass% Si, 0.80 mass% Cu, 0.15 mass% Fe, and 1.50 mass% Mn, but without Sr.

[0022] Then, the inventors stacked two plates with a thickness of 1.0 (mm) × width of 50 (mm) × length of 150 (mm) formed of the aluminum alloy materials of Comparative Examples 1 and 2, and welded them with a laser with an output of 6 kW at a welding speed of 15 m / min to check for the presence or absence of welding cracks. No welding cracks were observed in the aluminum alloy material of Comparative Example 1, but welding cracks were observed in the aluminum alloy material of Comparative Example 2.

[0023] Also, the analytical value of the brittle temperature range ΔT in Comparative Example 1 was 21°C, the 0.2% proof stress was 40 MPa, the tensile strength was 110 MPa, and the elongation was 30%. Further, the analytical value of the brittle temperature range ΔT in Comparative Example 2 was 67°C, the 0.2% proof stress was 50 MPa, the tensile strength was 145 MPa, and the elongation was 20%. Also, the analytical value of the brittle temperature range ΔT of the aluminum alloy material of the present disclosure containing 4.5 mass% of Si, 0.20 mass% of Cu, 0.35 mass% of Fe, 1.50 mass% of Mn, and 0.01 mass% of Sr is 5°C, the analytical value of the 0.2% proof stress is 60 MPa, the analytical value of the tensile strength is 155 MPa, and the analytical value of the elongation is 20%.

[0024] From the results of the welding tests as described above, and the brittle temperature ranges and various properties of Comparative Examples 1 and 2, it will be understood that in the aluminum alloy material of the present disclosure in which the brittle temperature range ΔT can be made less than 21°C, while improving the proof stress and strength by increasing the amounts of Si and Cu that promote solid solution strengthening, the occurrence of welding cracks can be extremely well suppressed. Also, in the battery thermostat 10 including the first and second plate members 11 and 12 formed of the aluminum alloy material of the present disclosure that can suppress welding cracks well, productivity can be improved by adopting laser welding or the like. However, it goes without saying that the aluminum alloy material of the present disclosure can be applied to structures other than the battery thermostat 10. Further, the aluminum alloy material of the present disclosure can also be applied as a material for a clad material combined with a corrosion prevention material or the like.

[0025] Furthermore, the invention disclosed herein is not limited in any way to the embodiments described above, and it goes without saying that various modifications can be made within the scope of this disclosure. Moreover, the embodiments described above are merely one specific form of the invention described in the summary of the invention, and do not limit the elements of the invention described in the summary of the invention. [Industrial applicability]

[0026] The invention disclosed herein can be used in industries such as the manufacturing of aluminum alloy materials and battery temperature controllers. [Explanation of Symbols]

[0027] 10 Battery temperature controller, 11 First plate member, 12 Second plate member, 15, 16 Heat transfer medium passage.

Claims

1. An aluminum alloy material comprising 4.0% by mass or more and 6.0% by mass or less of Si (silicon), 0.01% by mass or more and 1.4% by mass or less of Cu (copper), 0.01% by mass or more and 0.7% by mass or less of Fe (iron), 1.01% by mass or more and 2.0% by mass or less of Mn (manganese), 0.01% by mass or more and 1.5% by mass or less of Mg (magnesium), 0.01% by mass or more and 0.2% by mass or less of Zn (zinc), 0.01% by mass or more and 0.2% by mass or less of Cr (chromium), 0.01% by mass or more and 0.2% by mass or less of Zr (zirconium), 0.01% by mass or more and 0.2% by mass or less of Ti (titanium), 0.01% by mass or more and 0.2% by mass or less of V (vanadium), and 0.001% by mass or more and 0.1% by mass or less of Sr (strontium), with the remainder being Al (aluminum) and unavoidable impurities.

2. In the aluminum alloy material described in claim 1, An aluminum alloy material containing 4.0% by mass or more and 5.0% by mass or less of Si, 0.2% by mass or more and 0.8% by mass or less of Cu, 1.2% by mass or more and 1.8% by mass or less of Mn, and 0.005% by mass or more and 0.03% by mass or less of Sr.

3. In the aluminum alloy material according to claim 2, An aluminum alloy material containing 0.2% by mass or more and 0.6% by mass or less of Fe, 0.01% by mass or more and 0.4% by mass or less of Mg, 0.01% by mass or more and 0.1% by mass or less of Zn, 0.01% by mass or more and 0.1% by mass or less of Cr, 0.01% by mass or more and 0.1% by mass or less of Zr, 0.01% by mass or more and 0.1% by mass or less of Ti, and 0.01% by mass or more and 0.1% by mass or less of V.

4. A battery temperature controller comprising two plate members formed from an aluminum alloy material according to any one of claims 1 to 3, wherein at least one of the plate members has a heat transfer medium passage formed therein and the two plate members are joined to each other by welding.

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