JP2015045033A - Aluminum alloy casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy casting by a gravity casting method capable of reducing cost, and capable of satisfactorily conducting caulking by plastic deformation.SOLUTION: The aluminum alloy casting contains Fe:0.08 to 0.50% (mass%, the same shall apply hereinafter), Si:4.5 to 7.5%, Mg:0.25 to 0.7%, Zn:0.30% or less, Ca:0.005% or less, Sr:0.001 to 0.05% or less and the balance Al and further Ti:0.10 to 0.20% and B:0.0001 to 0.01%.

Description

  The present invention relates to an aluminum alloy casting excellent in plastic working such as caulking.

  In order to reduce the weight of a brake fluid pressure control device for a vehicle, the body is made of an aluminum alloy. In addition, a steel member (such as a flow rate adjusting tool) that is difficult to weld to the aluminum alloy is attached to the main body by caulking that plastically deforms a part of the aluminum alloy. Therefore, a wrought material is often used for an aluminum alloy as an alloy material having high toughness that can obtain the elongation required for caulking (Patent Document 1). However, the wrought material is expensive and has a drawback of high cost.

  Patent Document 2 discloses an aluminum alloy that can be attached to a steel member satisfactorily by die casting or by toughness by adjusting the composition of Ti, Ca, B, and P as components. The casting and its manufacturing method are shown.

JP 2004-2947 A Japanese Patent Laid-Open No. 2001-200325

However, since what is disclosed in Patent Document 2 is an aluminum alloy by a die casting method, there is a problem that the manufacturing cost increases.
Therefore, it is preferable to provide an aluminum alloy casting by a gravity casting method capable of reducing the cost.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an aluminum alloy casting that can be cost-reduced and can be caulked well by plastic deformation. There is.

In order to achieve the above object, the present invention comprises the following arrangement.
That is, the aluminum alloy casting according to the present invention has Fe: 0.08 to 0.50% (mass%, the same shall apply hereinafter), Si: 4.5 to 7.5%, Mg: 0.25 to 0.7%, Zn: 0.30% or less, Ca: 0.005% or less , Sr: 0.001 to 0.05% or less, and the balance is an aluminum alloy casting made of Al, and further includes Ti: 0.10 to 0.20% and B: 0.0001 to 0.01%.

Further, it is characterized by being cast by a gravity casting method.
Further, another fixing member is fixed by being partly plastically deformed.
Further, Mn: 0.01 to 0.2%, Cr: 0.01 to 0.3%, Na: 0.001 to 0.01%, P: 0.001% or less, Zr: 0.0005 to 0.2%, containing any one or more of them. Features.

According to the aluminum alloy casting according to the present invention, when the crystal is refined and crushed by caulking, the influence due to the difference in elongation direction due to each crystal is reduced, and the caulking portion is uniformly stretched and fixed. The recesses and grooves of the member are uniformly filled and good caulking can be performed.
In addition, since the material is obtained from the conventional aluminum alloy material (A356) for gravity casting, the casting manufacturing method does not change from the conventional gravity casting method, and an inexpensive gravity casting method can be used.
For example, when used in the main body of a vehicle brake hydraulic pressure control device, the caulking portion that is plastically deformed during caulking is uniformly filled into the recesses and grooves of the mating part (fixing member), so there is less variation for each caulking site. This improves the sealing performance.

It is an enlarged photograph of the section organization of the casting which carried out gravity casting using A356 to aluminum alloy material. It is an enlarged photograph of the section structure of the casting which carried out the gravity casting using the material concerning this embodiment to the aluminum alloy material. It is explanatory drawing which shows the deformation | transformation direction by the caulking pressure of the casting shown in FIG. It is explanatory drawing which shows the deformation | transformation direction by the crimping pressure of the casting shown in FIG. It is explanatory drawing which shows the state which fixes a fixing member to an aluminum alloy material by crimping. It is an enlarged photograph which shows the surface state of the crimping part when an aluminum alloy material is a wrought material. It is an enlarged photograph which shows the surface state of the crimping part of a casting (gravity casting method) when an aluminum alloy material is based on A356. It is an enlarged photograph which shows the surface state of the crimping part of a casting (gravity casting method) when an aluminum alloy material is the material of this Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
As described above, the aluminum alloy casting according to the present embodiment is Fe: 0.08 to 0.50% (mass%, the same applies hereinafter), Si: 4.5 to 7.5%, Mg: 0.25 to 0.7%, Zn: 0.30% or less, Ca: 0.005% or less, Sr: 0.001 to 0.05% or less, the balance being an aluminum alloy casting made of Al, further comprising Ti: 0.10 to 0.20%, B: 0.0001 to 0.01% . In addition to the above, inevitable impurities may naturally be included.

The Fe component is an effective alloy component that prevents seizure of the mold. Formation of coarse intermetallic compound crystals can be suppressed within the above composition range.
The Si component is an alloy component effective for improving the mechanical strength. Moreover, the production | generation of coarse eutectic Si can be suppressed in the range of the said composition.
As is well known, the Mg component is an alloy component that precipitates as Mg ₂ Si by aging treatment and imparts mechanical strength.

The Zn component is an alloy component that imparts mechanical strength in combination with the Mg component.
The Ca component improves strength and toughness and improves plastic deformability.
The Ti component must coexist with the B component, and the structure can be reduced by suppressing the crystal growth of Al. In Patent Document 2, if the Ti component is 0.02 to 0.1% by mass, Ti exceeding 0.1% by mass and B exceeding 0.01% by mass are included, a coarse compound is easily generated, and the elongation of the aluminum alloy casting is increased. It is said that a downward trend is shown.

  However, in the present embodiment, the Ti component is effective in the range of 0.10 to 0.20 mass% as described above, and by the gravity casting method, the growth of Al crystals is suppressed with TiB as the nucleus, and the crystals are finely divided. Can be Thereby, toughness improves and caulking by plastic deformation is enabled. In the case of the gravity casting method, when the Ti component is out of the above composition range, the Al crystal tends to be coarsened.

The Sr component makes the eutectic Si phase finer and improves the toughness of the aluminum alloy casting.
As other components, as described above, any one of Mn: 0.01 to 0.2%, Cr: 0.01 to 0.3%, Na: 0.001 to 0.01%, P: 0.001% or less, Zr: 0.0005 to 0.2% You may make it contain above.

Table 1 shows a composition table of the aluminum alloy. As a reference example, the composition of aluminum alloy: A356 and AC4CH is also shown.

The molten aluminum alloy containing the above components is poured into a mold by a gravity casting method, and the temperature range between the liquidus and solidus is DAS2 of 25 to 60 μm, 0.45 to 0 The aluminum alloy casting was obtained by cooling to room temperature at a cooling rate of 70 ° C./second.
FIG. 1 shows an enlarged photograph (FIG. 1B) of a cross-sectional structure of an aluminum alloy casting using A356 material. FIG. 1A is a diagram showing an enlarged portion (broken line portion). FIG. 2 shows an enlarged photograph (FIG. 2B) of a cross-sectional structure of an aluminum alloy casting using the A356 improved material of the present embodiment. FIG. 2A is a diagram showing an enlarged portion (broken line portion).

  As shown in FIG. 1, the A356 material has a large dendrite (dendritic Al) structure, the composition growth direction during solidification is non-uniform, and the direction of crystal elongation differs when caulking is applied. The filling property of the (members fixed by caulking) into the recesses, grooves and the like is lowered, and the adhesion to the rigid member is deteriorated. FIG. 3 is an explanatory view showing the crystal growth direction when caulking is applied in the case of A356 material.

  As shown in FIG. 2, the aluminum alloy material (improved A356) according to the present embodiment suppresses the growth of Al crystals with TiB as a nucleus, resulting in fine crystal grains. Since the crystals are finer in this way, the influence of different elongation directions of each crystal during caulking is reduced (FIG. 4), and due to uniform plastic deformation due to caulking, the recesses and grooves of the rigid member are formed. Thus, the aluminum alloy adheres closely to the steel member, and good caulking can be performed. For this reason, in the case of a brake fluid pressure control device for a vehicle, fluid leakage can be effectively prevented.

  FIG. 5 is an explanatory view for fixing a steel member 2 by caulking a part of the aluminum alloy material 1. Thus, after pressurizing aluminum alloy material 1 in the direction of arrow A with a caulking jig (not shown) and fixing steel member 2 to aluminum alloy material 1, aluminum alloy in a state where steel member 2 is peeled off The surface state of the crimped portion of the material 1 (the state in the dotted circle 3) is shown in FIGS. 6 shows the case where the aluminum alloy material is an extruded material (stretched material), FIG. 7 shows the case of an A356 material that is a casting material, and FIG. 8 shows the case of the aluminum alloy material (A356 improved material) of the present embodiment. .

When the aluminum alloy material is an extruded material (stretched material), it is excellent in toughness. As clearly shown in FIG. It turns out that it fixes well.
In this regard, when the aluminum alloy material is A356 material, since the aluminum alloy casting after gravity casting is inferior in toughness, as clearly shown in FIG. It can be seen that there is a problem with the adhesiveness of the material, and good caulking cannot be performed.

  When the aluminum alloy material is the present embodiment (A356 improved material), the toughness is improved and, as clearly shown in FIG. 8, the crimped portion of the aluminum alloy casting after gravity casting is uniformly plastically deformed. The surface has less irregularities and the rigid member is fixed with good adhesion. As can be seen from FIGS. 6 and 8, it can be said that the aluminum alloy casting of the present embodiment has the same toughness as the wrought material. And since it is obtained by a gravity casting method, cost reduction can be achieved.

1 Aluminum alloy material 2 Steel member 3 Dotted circle

Claims (4)

Fe: 0.08 to 0.50% (mass%, the same applies hereinafter), Si: 4.5 to 7.5%, Mg: 0.25 to 0.7%, Zn: 0.30% or less, Ca: 0.005% or less, Sr: 0.001 to 0.05% or less And the balance is an aluminum alloy casting made of Al,
An aluminum alloy casting characterized by further containing Ti: 0.10 to 0.20% and B: 0.0001 to 0.01%.   An aluminum alloy casting characterized by being cast by gravity casting.   3. The aluminum alloy casting according to claim 2, wherein another fixing member is fixed by being partly plastically deformed.   Furthermore, Mn: 0.01-0.2%, Cr: 0.01-0.3%, Na: 0.001-0.01%, P: 0.001% or less, Zr: 0.0005-0.2%, containing any one or more The aluminum alloy casting according to any one of claims 1 to 3.