ALUMINUM ALLOY AND ALUMINUM ALLOY CASTING MATERIAL

Abstract

The present invention provides an aluminum alloy that has exceptional casting properties and that can exhibit high mechanical properties without being subjected to a heat treatment, and an aluminum alloy casting material. More specifically, the present invention provides: an aluminum alloy that has exceptional casting properties, and that has a high 0.2% proof stress and exceptional ductility without being subjected to a heat treatment; and an aluminum alloy casting material. The aluminum alloy according to the present invention is characterized by containing 7.0-9.0 mass % of Si, 2.0-4.0 mass % of Cu, 0.8-1.2 mass % of Mg, 0.3-0.5 mass % of Fe, 0.3-0.5 mass % of Mn, and. 2.0-4.0 mass % of Zn, the balance being Al and unavoidable impurities.

Claims

1. An aluminum alloy comprising: Si: 7.0 to 9.0% by mass, Cu: 2.0 to 4.0% by mass, Mg: 0.8 to 1.2% by mass, Fe: 0.3 to 0.5% by mass, Mn: 0.3 to 0.5% by mass, Zn: 2.0 to 4.0% by mass, and the balance being Al and unavoidable impurities.

2. The aluminum alloy according to claim 1, which contains at least one of Sr: 0.008 to 0.04% by mass, Be: 0.001 to 0.004% by mass, Ti: 0.05 to 0.005% by mass, B: 0.01 to 0.005% by mass.

3. An aluminum alloy casting material which comprises the aluminum alloy according to claim 1, has a 0.2% proof stress of 230 MPa or more and an elongation at break of 2.5% or more.

Description

EXAMPLE

Example

[0045] In Table 1, aluminum alloys having the compositions described as Examples 1 to 5 were produced by melting and die-cast at a casting pressure of 120 MPa, a molten metal temperature of 730 C., and a mold temperature of 170 C. The mold shape is a plate of 55 mm110 mm3 mm. The aluminum alloy has excellent die-casting property, and a good aluminum alloy casting material (die-cast material) was obtained. The unit of the numerical values shown in Table 1. is % concentration by mass.

TABLE-US-00001 TABLE 1 Si Cu Mg Fe Mn Zn Be Sr Al Ex. 1 8.0 3.0 1.0 0.4 0.4 3.0 0.003 0.020 Bal. Ex. 2 9.0 2.2 1.2 0.3 0.5 2.1 0.001 0.025 Bal. Ex. 3 7.2 3.9 0.8 0.5 0.3 3.9 0.038 Bal. Ex. 4 8.2 3.1 0.9 0.4 0.4 3.1 0.008 Bal. Ex. 5 7.7 2.8 1.1 0.5 0.5 2.8 0.004 0.012 Bal. Com. Ex. 1 11.0 4.5 0.8 0.25 1.0 0.015 Bal. Com. Ex. 2 11.0 4.5 1.0 0.4 1.0 0.010 Bal. Com. Ex. 3 11.0 4.5 1.0 0.4 1.0 1.0 0.010 Bal. Com. Ex. 4 10.5 4.5 1.0 0.4 1.0 3.0 0.010 Bal. Com. Ex. 5 10.0 4.5 1.0 0.4 1.0 5.0 0.010 Bal. Com. Ex. 6 9.0 3.5 2.0 0.8 0.003 0.020 Bal. Com. Ex. 7 9.0 3.5 2.0 0.8 3.0 0.003 0.020 Bal. Com. Ex. 8 9.0 3.5 2.0 0.8 5.0 0.003 0.020 Bal. Com. Ex. 9 9.0 3.5 1.0 0.8 0.020 Bal. Com. Ex. 10 9.0 3.5 1.5 0.8 Bal. Com. Ex. 11 8.0 3.0 0.5 0.4 0.4 0.003 0.020 Bal. Com. Ex. 12 8.0 3.0 0.5 0.4 0.4 3.0 0.003 0.020 Bal. Com. Ex. 13 8.9 3.6 0.51 0.78 <0.01 <0.01 0.003 0.020 Bal. Com. Ex. 14 8.9 3.6 1.1 0.79 <0.01 <0.01 0.003 0.020 Bal. Com. Ex. 15 8.8 3.6 1.5 0.79 <0.01 <0.01 0.003 0.020 Bal. Com. Ex. 16 8.8 3.7 0.79 0.81 <0.01 <0.01 0.003 0.020 Bal. Com. Ex. 17 7.3 3.6 0.6 0.76 <0.01 <0.01 0.003 0.020 Bal. Com. Ex. 18 7.3 3.6 0.9 0.77 <0.01 <0.01 0.002 0.020 Bal. Com. Ex. 19 7.3 3.6 1.2 0.77 <0.01 <0.01 0.003 0.020 Bal. Com. Ex. 20 1.9 <0.01 7.1 0.19 0.7 <0.01 0.003 Bal. Com. Ex. 21 6.8 3.0 1.0 0.4 0.6 1.8 0.003 0.020 Bal. Com. Ex. 22 7.9 1.7 0.9 0.4 0.1 2.9 0.003 0.020 Bal.

[0046] A No. 14B test piece defined in JIS-Z2241 was taken from each of the obtained aluminum alloy casting materials, and when the tensile test was performed at room temperature, the values shown in Table 2 of the tensile strength, the 0.2% proof stress and elongation at break were obtained. Further, when the Rockwell hardness of the obtained aluminum alloy casting materials were measured, the values shown in Table 2 were obtained. Here, the aluminum alloy casting materials were die-cast as they were, and was not subjected to heat treatment such as aging treatment.

TABLE-US-00002 TABLE 2 Tensile 0.2% Proof strength stress Elongation Hardness (MPa) (MPa) (%) (HRB) Ex. 1 369 241 3.3 73 Ex. 2 362 237 2.7 Ex. 3 383 247 2.6 Ex. 4 365 242 3.2 Ex. 5 371 245 3.0 Com. Ex. 1 336 230 1.6 77 Com. Ex. 2 362 237 2.0 77 Com. Ex. 3 317 231 1.2 76 Com. Ex. 4 347 241 1.6 78 Com. Ex. 5 330 251 1.3 79 Com. Ex. 6 357 298 1.1 77 Com. Ex. 7 385 301 1,5 78 Com. Ex. 8 366 302 1.0 79 Com. Ex. 9 357 239 2.2 76 Com. Ex. 10 385 253 1.6 77 Com. Ex. 11 59 Com. Ex. 12 59 Com. Ex. 13 328 227 2.4 Com. Ex. 14 328 271 1.5 Com. Ex. 15 333 325 1.0 Com. Ex. 16 333 241 1.8 Com. Ex. 17 316 207 2.4 Com. Ex. 18 347 244 2.4 Com. Ex. 19 350 282 1.5 Com. Ex. 20 294 190 4.1 Com. Ex. 21 366 241 2.2 Com. Ex. 22 349 225 2.3

Comparative Example

[0047] Comparative aluminum alloy casting materials (die cast materials) were obtained in the same manner as in the Examples, except that the molten material was prepared so as to have the components described in Table 1 as Comparative Examples 1 to 22. Further, the tensile properties and Rockwell hardness were measured in the same manner as in Examples. The values obtained are shown in Table 2. In addition, when there is no description of a numerical value, it means that the measurement was not performed.

[0048] Comparing the tensile properties of the aluminum alloy casting materials obtained in Examples and Comparative Examples, it can be seen that only the aluminum alloy casting materials obtained in Examples have a 0.2% proof stress of 230 MPa or more and an elongation at break of 2.5% or more. Further, it can be seen that Example 1 with Sr added has higher tensile strength and elongation than Example 4 with no Sr added (extremely low Sr content).

[0049] The aluminum alloy casting materials having the compositions of Comparative Examples 1 to 5, which contain a large amount of Si, Cu and Mn, exhibit a high 0.2% proof stress, but the elongation at break is 2.0% or less. Further, the elongation at break of the aluminum alloy casting materials having the compositions of Comparative Examples 6 to 10 and Comparative Examples 13 to 19, which contain a large amount of Fe, does not reach 2.5%.

[0050] Further, the hardness of the aluminum alloy casting materials having the compositions of Comparative Example 11, in which the amount of Mg added is small and does not contain Zn, and Comparative Example 12, in which the amount of Mg added is small, are low values, and it can be seen that sufficient strength is not obtained.

[0051] Furthermore, the aluminum alloy casting material having the composition of Comparative Example 20 with low Si and Cu contents has an elongation at break of 2.5% or more, but a low 0.2% proof stress. Further, in Comparative Example 21, in which the Si and Zn contents are low and the Cu and Mn contents are high, the tensile strength and 0.2% proof stress are high, but the elongation at break is as low as less than 2.5%. Further, in Comparative Example 22, in which the Cu and Mn contents are high, the elongation at break is as low as less than 2.5%, and in addition the 0.2% proof stress does not reach 230 MPa.

[0052] From the above results, in order to develop the 0.2% proof stress of 230 MPa or more and the elongation at break of 2.5% or more without subjecting the aluminum alloy casting material to heat treatment, it can be seen that it is necessary to strictly control the addition amounts of Si, Cu, Mg, Fe, Mn and Zn.