JP2007070716A - Aluminum alloy for pressure casting, and aluminum alloy casting made thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy for pressure casting which facilitates production of an ingot, has high proof stress and elongation, and is hard to be seized, and to provide an aluminum alloy casting obtained by subjecting the same alloy to pressure casting and having high toughness. <P>SOLUTION: The aluminum alloy comprises, by weight, 6.0 to 12.0% Si, 0.5 to 1.0% Mg, 0.1 to 0.5% Cr and ≤0.5% Fe, and the balance Al with inevitable impurities. By this constitution, the aluminum alloy having proof stress and elongation more excellent than those of the existent ADC12, and further hard to be seized can be provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aluminum alloy for pressure casting excellent in toughness and an aluminum alloy casting using the alloy.

  Aluminum alloys are widely used as component materials in automobiles, industrial machines, aircraft, home appliances and other various fields because of their light weight and various characteristics such as excellent thermal conductivity and high corrosion resistance. One of them is the field of aluminum casting alloys, and a typical example thereof is an Al—Si—Cu casting alloy represented by ADC10 or ADC12. This Al—Si—Cu-based cast alloy has been widely used in applications such as covers and cases such as automobile carburetors, cylinder blocks and cylinder head covers, or cast parts other than automobiles, especially die-cast parts.

However, from the viewpoint of reducing the weight of automobiles and other machinery due to the recent promotion of energy-saving measures, active introduction of die-cast parts is also being studied in areas where force is applied, and aluminum alloys used for such applications are being investigated. However, the castability is not only more economical than the original, but also requires higher yield strength and elongation than the existing ADC 12 (see Patent Document 1).
JP 2001-49376 A (page 2)

  Therefore, a main object of the present invention is to provide an aluminum alloy for pressure casting that is excellent in yield strength and elongation and is difficult to seize, and an aluminum alloy casting having high toughness that is pressure-cast with the alloy.

  The invention described in claim 1 is described as follows: “Si: 6.0 to 12.0% by weight, Mg: 0.5 to 1.0% by weight, Cr: 0.1 to 0.5% by weight, and Fe: 0.0. It is an aluminum alloy for pressure casting characterized by containing 5% by weight or less and the balance being made of Al and inevitable impurities.

  In the present invention, since 6.0 to 12.0% by weight of Si is blended, the fluidity of the molten aluminum alloy can be improved while suppressing a decrease in elongation. Moreover, since 0.5 to 1.0% by weight of Mg is blended, the yield strength of the aluminum alloy can be improved while suppressing a decrease in elongation. Furthermore, since Cr is blended in an amount of 0.1 to 0.5% by weight, seizure between the aluminum alloy and the mold during casting can be prevented while suppressing a decrease in elongation. And since Fe is restrained to 0.5 weight% or less, the toughness fall of the aluminum alloy resulting from the crystallization of the acicular crystal | crystallization consisting of Al-Si-Fe can be suppressed.

  As described above, in the present invention, an aluminum alloy ingot for pressure casting that is excellent in proof stress and elongation and hardly seizure is produced only by adjusting the five elemental components so as to have a predetermined blending ratio. be able to.

  The invention described in claim 2 is characterized in that, in the aluminum alloy for casting according to claim 1, “at least one selected from Na, Sr and Ca is added in an amount of 30 to 200 ppm”. The invention described in Item 3 is characterized in that in the casting aluminum alloy according to Item 1 or 2, “0.05 to 0.20% by weight of Sb is added”.

  In these inventions, the particles of eutectic Si can be made finer, and the toughness and strength of the aluminum alloy can be further improved.

  The invention described in claim 4 is an aluminum alloy casting characterized by being "press-cast with the aluminum alloy according to any one of claims 1 to 3".

  A casting (for example, die-cast part) press-cast with the aluminum alloy according to any one of claims 1 to 3 can be mass-produced with good castability and has excellent proof stress and elongation (that is, high toughness). It can also be applied to a member to which a force is applied, for example, a structural component for an automobile, which is repeatedly subjected to a vibration load for a long time and to which an impact is applied at the time of a collision.

  According to the present invention, it is possible to provide an aluminum alloy for pressure casting that is more excellent in yield strength and elongation than existing ADC 12 and that is difficult to seize, and an aluminum alloy casting having high toughness that is pressure cast with the alloy. .

  Hereinafter, embodiments of the present invention will be described in detail with specific examples.

  The aluminum alloy for pressure casting of the present invention (hereinafter simply referred to as “aluminum alloy”) is mainly composed of 6.0 to 12.0 wt% Si, 0.5 to 1.0 wt% Mg, 0.1 It contains ˜0.5% by weight of Cr and 0.5% by weight or less of Fe, and the balance is composed of Al and inevitable impurities.

  Si is for improving fluidity when aluminum alloy is melted and pressure cast.

  As described above, the blending ratio of Si with respect to the weight of the entire aluminum alloy is preferably in the range of 6.0 to 12.0% by weight. When the Si content is less than 6.0% by weight, the melting temperature and casting temperature of the aluminum alloy increase, and the fluidity when the aluminum alloy is melted decreases, so that a sufficient amount of hot water flows during pressure casting. On the other hand, when the Si content is more than 12.0% by weight, the flowability when the aluminum alloy is melted will be sufficient, but the elongation will decrease. is there.

Mg exists mainly as a solid solution in an Al base material in an aluminum alloy or as Mg ₂ Si, and is for imparting proof stress and tensile strength to the aluminum alloy.

  As described above, the mixing ratio of Mg with respect to the weight of the entire aluminum alloy is preferably in the range of 0.5 to 1.0% by weight. When the Mg content is less than 0.5% by weight, mechanical properties such as yield strength and tensile strength are not sufficiently improved. Conversely, when the Mg content is more than 1.0% by weight This is because the elongation of the aluminum alloy suddenly decreases.

  Cr is mainly in a molten state when the aluminum alloy is melted, and in a state where it is solidified in the Al phase or crystallized as an Al-Si-Cr phase or Al-Si-Cr-Fe phase when it is solid. It exists to prevent seizure between the aluminum alloy and the mold during casting of the aluminum alloy.

  As described above, the mixing ratio of Cr with respect to the weight of the entire aluminum alloy is preferably in the range of 0.1 to 0.5% by weight. When the blending ratio of Cr is less than 0.1% by weight, seizure occurs between the aluminum alloy and the mold when the aluminum alloy is pressure cast, and conversely, the blending ratio of Cr is This is because, when the amount is more than 0.5% by weight, the seizure at the time of pressure casting is eliminated, but the elongation of the aluminum alloy suddenly decreases.

  Fe is known to have an effect of preventing seizure during pressure casting, and is added to a general die casting aluminum alloy such as ADC12 in an amount of 0.5% by weight or more. However, this Fe crystallizes needle-like crystals made of Al-Si-Fe, and lowers the toughness of the aluminum alloy. For this reason, in the present invention, in order to prevent a decrease in toughness of the aluminum alloy due to Fe, the content of Fe is suppressed to 0.5% by weight or less, while Cr is 0.1 to 0 as an anti-seizing material as described above. .5% by weight blended to prevent seizure during pressure casting.

  The aluminum alloy of the present invention contains Al and inevitable impurities as a base material in addition to the above-described components (Si, Mg, Cr, Fe).

  Adjusting the mixing ratio of Si, Mg, Cr, and Fe according to the above mixing ratio can prevent seizure between the aluminum alloy and the mold during the pressure casting, and also has excellent proof stress and elongation. Aluminum alloy ingots can be obtained.

  In addition to each elemental component described above, at least one selected from Na, Sr, Ca and Sb may be added as an improvement treatment material. By adding such an improved treatment material, the particles of eutectic Si can be made finer, and the toughness and strength of the aluminum alloy can be further improved.

  Here, the addition ratio of the improved material to the total weight of the aluminum alloy is 30 to 200 ppm when the improved material is Na, Sr and Ca, and 0.05 to 0.20% by weight when Sb. A range is preferable. When the addition ratio of the improved treatment material is less than 30 ppm (0.05% by weight in the case of Sb), it becomes difficult to refine the eutectic Si particles in the aluminum alloy. When the addition ratio of the alloy is more than 200 ppm (0.20% by weight in the case of Sb), the eutectic Si particles in the aluminum alloy are sufficiently refined and added even if the addition amount is further increased. This is because the effect does not increase.

  When manufacturing the aluminum alloy of the present invention, first, raw materials are prepared so that each elemental component of Al, Si, Mg, Cr, and Fe has the above-mentioned predetermined ratio. Subsequently, this raw material is put into a melting furnace such as a pre-furnace melting furnace or a closed melting furnace to melt them. The melted raw material, that is, the molten aluminum alloy is subjected to a purification treatment such as a dehydrogenation treatment and a decontamination treatment as necessary. Then, the refined molten metal is poured into a predetermined mold or the like and solidified to form the molten aluminum alloy into an alloy ingot or the like.

  Further, when an aluminum alloy casting (cast product) is cast using the aluminum alloy of the present invention, a pressure casting method such as a die casting method is used. By using the pressure casting method in this way, the cast product can be mass-produced efficiently.

  And the aluminum alloy casting obtained by these casting methods is subjected to a solution treatment and an aging treatment as necessary. Thus, the mechanical properties of the aluminum alloy casting can be improved by subjecting the aluminum alloy casting to solution treatment and aging treatment.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.

  In addition, each mechanical characteristic (tensile strength, elongation, 0.2% yield strength) in Examples and Comparative Examples was measured with a universal testing machine (AG-IS 100 kN) manufactured by Shimadzu Corporation.

[Example 1]
The Si content is 7.02% by weight, the Mg content is 0.58% by weight, the Cr content is 0.29% by weight, the Fe content is 0.45% by weight, and the balance is Al. Thus, a molten metal was prepared so as to be within the range of the elemental composition of the aluminum alloy in the present invention. Subsequently, this molten metal is die-cast at an injection speed of 5 m / sec (gate speed of 100 m / sec) using a normal die casting machine instead of vacuum die casting, and a round bar test conforming to the ASTM (American Society for Testing and Material) standard. A piece was made. The produced round bar test piece was treated with T5 to obtain a sample for measuring mechanical properties. The mechanical properties of the obtained sample are shown in Table 1.

  The T5 treatment is a heat treatment method in which the solution is rapidly cooled from the casting temperature without performing solution treatment, and then subjected to artificial aging treatment in order to improve mechanical characteristics or stabilize dimensions. As specific heat treatment conditions (artificial aging treatment), the mixture was heated at 170 ° C. for 3 hours and then air-cooled.

[Example 2]
The compounding ratio of Si is 7.12% by weight, the compounding ratio of Mg is 0.76% by weight, the compounding ratio of Cr is 0.29% by weight, the existence ratio of Fe is 0.47% by weight, and Mn is an inevitable impurity. A sample for measuring mechanical properties was prepared under the same conditions as in Example 1 except that 0.01% by weight was included. The mechanical properties of the obtained sample are shown in Table 1.

[Example 3]
The Si content is 9.40% by weight, the Mg content is 0.62% by weight, the Cr content is 0.31% by weight, the Fe content is 0.41% by weight, and Mn is an inevitable impurity. A sample for measuring mechanical properties was prepared under the same conditions as in Example 1 except that 0.01% by weight was included. The mechanical properties of the obtained sample are shown in Table 1.

[Example 4]
The Si content is 9.47 wt%, the Mg content is 0.52 wt%, the Cr content is 0.31 wt%, the Fe content is 0.40 wt%, and Mn is an inevitable impurity. A sample for measuring mechanical properties was prepared under the same conditions as in Example 1 except that 0.01% by weight was included. The mechanical properties of the obtained sample are shown in Table 1.

[Example 5]
The Si compounding ratio is 9.50% by weight, the Mg compounding ratio is 0.62% by weight, the Cr compounding ratio is 0.43% by weight, the Fe existing ratio is 0.45% by weight, and Mn is an inevitable impurity. A sample for measuring mechanical properties was prepared under the same conditions as in Example 1 except that 0.01% by weight was included. The mechanical properties of the obtained sample are shown in Table 1.

[Example 6]
Example except that the compounding ratio of Si was 9.89% by weight, the compounding ratio of Mg was 0.60% by weight, the compounding ratio of Cr was 0.31% by weight, and the existence ratio of Fe was 0.09% by weight. A sample for measuring mechanical properties was prepared under the same conditions as in 1. The mechanical properties of the obtained sample are shown in Table 1.

[Example 7]
The compounding ratio of Si is 10.2% by weight, the compounding ratio of Mg is 0.58% by weight, the compounding ratio of Cr is 0.43% by weight, the existence ratio of Fe is 0.47% by weight, and Mn is an inevitable impurity. A sample for measuring mechanical properties was prepared under the same conditions as in Example 1 except that 0.03% by weight was included. The mechanical properties of the obtained sample are shown in Table 1.

[Comparative example]
An existing ADC 12 was used as a comparative example. Specifically, a melt containing each element component was prepared at the ratio shown in Table 1. Subsequently, this molten metal was die-cast at an injection speed of 5 m / sec (gate speed of 100 m / sec) by a normal die casting machine instead of vacuum die casting, and a round bar test piece compliant with the ASTM standard was produced. The produced round bar test piece was treated with T5 to obtain a sample for measuring mechanical properties. The mechanical properties of the obtained sample are shown in Table 1.

  From Table 1, the aluminum alloys of Examples 1 to 7 have 0.2% higher proof stress and higher elongation than the existing ADC12 alloy. That is, it can be seen that the aluminum alloys of Examples 1 to 7 have higher toughness than the ADC12 alloy.

  In each of Examples 1 to 7 described above, die casting was performed at an injection speed of 5 m / sec (gate speed of 100 m / sec), but at that time, seizure occurred between the aluminum alloy and the mold. There wasn't.

The aluminum alloy of the present invention can be widely used not only as a vehicle component but also as a component material of various devices such as industrial machines and household appliances, and is particularly subjected to repeated vibration loads for a long period of time and is subjected to an impact at the time of collision. Suitable for parts material.

Claims (4)

  Si: 6.0 to 12.0% by weight, Mg: 0.5 to 1.0% by weight, Cr: 0.1 to 0.5% by weight and Fe: 0.5% by weight or less, the balance being An aluminum alloy for pressure casting characterized by comprising Al and inevitable impurities.   The aluminum alloy for pressure casting according to claim 1, wherein 30 to 200 ppm of at least one selected from Na, Sr and Ca is added.   The aluminum alloy for pressure casting according to claim 1 or 2, wherein 0.05 to 0.20% by weight of Sb is added. An aluminum alloy casting characterized by being pressure cast with the aluminum alloy according to any one of claims 1 to 3.