JP2923823B2 - Casting method of Al-based alloy casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of casting an Al-based alloy casting, and more particularly, to heating a solid material made of an Al-based hypoeutectic alloy.
The present invention also relates to a casting method for an Al-based alloy casting, in which a semi-molten casting material in which a solid phase and a liquid phase coexist is prepared, and then the casting material is cast under pressure . Casting method such as this is one that has been developed aims to improve the casting quality of the castings.

[0002]

2. Description of the Related Art Conventionally, as a casting method using such a casting material, a method disclosed in JP-A-60-152358 is known.

[0003]

The present inventors have made various studies on this type of casting method, and as a result, have found that the casting material can be adjusted.
In the solid material used for the production, the shape factor F is F ≧
Area ratio of the primary crystal alpha-Al is 0.1, the properties of the casting material at the time of passing through the gate, with increasing pressure, etc. for casting material filled in the cavity affects the casting quality and mechanical properties of the casting Casting It also affects the management of conditions, and the above-mentioned pressing force also causes operational problems such as generation of burrs, and furthermore, improves the productivity without impairing the casting quality and mechanical properties of the casting. In order to achieve this, it has been found that it is necessary to appropriately set the speed of the casting material when passing through the gate.

[0004] The present invention has been developed in view of such a fact. The first object of the present invention is to provide a solid material with a shape.
The area ratio of primary α-Al having a shape factor F of F ≧ 0.1 is characterized.
It is an object of the present invention to provide a casting method capable of improving casting quality of a casting by defining the casting method.

[0005] The second object is at a gate passage
By specifying the properties of the casting material,
An object of the present invention is to provide a casting method capable of improving quality and mechanical properties .

[0006] A third object is to provide a portable telephone at the time of passing through a gate.
Speed of casting material and casting material filled in cavity
Casting production by specifying the pressing force
And improve the workability, casting quality and mechanical properties
An object of the present invention is to provide a casting method capable of avoiding the above problems .

[0007]

Casting method of the Al-based alloy casting according to the present invention, in order to solve the problem] is made of Al-based hypoeutectic alloy solid material
Is heated in a semi-molten state where the solid and liquid phases coexist.
A material is prepared and then cast under pressure using said casting material.
In the casting method, the solid material is shaped as
Area ratio Ra of primary crystal α-Al whose shape factor F is F ≧ 0.1
Is set to Ra ≧ 80% .

[0008] casting method of the Al-based alloy casting according to the present invention, in addition to the conditions, the pre-Symbol casting material, the viscosity mu is 0.1Pa · sec ≦ μ ≦ 2000Pa · sec, also the Reynolds number Re Re It is characterized by passing through a mold gate under the condition of ≦ 1500 .

Further, in the method for casting an Al-based alloy casting according to the present invention, the speed of the casting material when passing through the gate may be increased.
V is 0.5 m / sec ≦ V ≦ 20 m / sec.
The casting material filled in the cavity of the mold
To pressurizing force P is wherein this <br/> and a 10 MPa ≦ P ≦ 120 MPa.

[0010]

The shape factor F is obtained by calculating the cross-sectional area of the primary crystal α-Al as A (total).
Measured value), and when the peripheral length is L (measured value), F = 4πA
/ L ² , the area L ^{2 of} a perfect circle with a perimeter L
Ratio of the cross-sectional area A of primary α-Al to / 4π, that is,
The circularity of primary crystal α-Al is shown. Therefore, the shape factor F
Takes a maximum value of 1.0 in a perfect circle, and the fracture of primary α-Al
Small enough to flatten the surface shape or make the shape more severe
Value.

[0011] Shape factor F of primary crystal α-Al and its area
When the ratio Ra is specified as described above, the gate material of the casting material is passed through the gate.
The viscosity μ at the time of passing, the viscosity that can avoid entrainment of gas
0.1 Pa · sec ≦ μ ≦ 2000 Pa · sec
To match the casting quality.
A good casting can be obtained. However, when the shape factor F is
When the area ratio Ra of primary α-Al with F <0.1 is Ra> 2
At 0%, the viscosity of the casting material when passing through the gate
Higher than the viscosity μ, and as a result, the casting quality of the casting
Decrease.

When the viscosity μ is set as described above, entrainment of gas by the casting material, and therefore, generation of pores in the casting can be prevented, and the casting quality can be improved. However, when the viscosity μ of the casting material is μ <0.1 Pa · se
When c becomes lower, the material becomes turbulent as the viscosity of the material decreases, so that the gas is easily entrained. On the other hand, when the viscosity μ is μ> 2
When the pressure reaches 000 Pa · sec, the pressure loss due to the deformation resistance increases with the increase in viscosity of the casting material, so that it becomes difficult for the casting material to pass through the gate, and an unfilled portion occurs in the cavity, resulting in chipping of the casting. Occurs.

The optimum range of the viscosity μ in the casting material is 1P
a · sec ≦ μ ≦ 1000 Pa · sec. The reason is that such a viscosity range can be easily realized by a conventional pressure casting apparatus having a mold temperature control mechanism. However, when the viscosity μ becomes as low as μ <1 Pa · sec, the speed of the casting material at the time of passing through the gate must be controlled at a low speed and precisely. Then it becomes difficult. On the other hand, when the viscosity μ increases as μ> 1000 Pa · sec, the casting material rapidly cools down due to the fact that the casting material is cooled by the mold, but in order to prevent this, the temperature of the mold must be controlled high. However, such control is difficult with a conventional pressure casting apparatus.

When the Reynolds number Re of the casting material is set as described above, the casting material can be made laminar to prevent entrainment of gas and generation of a cold shut. However, if the Reynolds number Re is Re> 15
At 00, the casting material is in a turbulent state, and the gas is easily entrained.

The optimum range of the Reynolds number Re is Re ≦ 10.
0. The reason is that the Reynolds number Re in such a casting material can be easily realized by a conventional pressure casting apparatus. However, when the Reynolds number Re is Re>
If it is set to 100, the influence of the inertial force becomes large depending on the shape of the cavity and the shape of the gate, so that the cavity is not smoothly filled with the casting material, and there is a possibility that gas is entrapped, a hot water boundary or the like is generated.

Further, when the speed V and the pressure P are set as described above, it is possible to improve the productivity and casting quality of the casting and to avoid operational problems. However, when the speed V becomes V <0.5 m / sec,
Since the filling time of the casting material into the cavity becomes longer, the viscosity of the casting material increases as the temperature of the casting material decreases, and an unfilled portion occurs in the cavity. On the other hand, when the speed V is V> 20 m /
At sec, the casting material is injected into the cavity as a jet flow from the gate, and the filling order of the casting material in the cavity is a deep region, followed by an inlet region, so that a hot boundary, entrainment of gas, and the like occur. .

When the pressure P is P <10 MPa, it is not possible to sufficiently press the high-viscosity casting material, and an unfilled portion occurs in the cavity. On the other hand, if the pressing force P becomes P> 120 MPa, operation problems such as generation of a large amount of burrs on the divided surface of the mold and intrusion of the casting material between the sleeve and the pressure plunger will occur .

[0018]

FIG. 1 schematically shows a pressure casting apparatus used for casting an Al-based alloy casting. Mold 1 of the pressure casting machine
Is composed of a fixed mold 2 and a movable mold 3 opposed to the fixed mold 2. The two dies 2 and 3 form a molding cavity 4 having a circular cross section and a gate 5 communicating with one end thereof. It communicates with the casting material inlet 6 of the mold 2. A sleeve 8 communicating with the loading port 6 is provided in the fixed mold 2, and a pressure plunger 9 inserted into and removed from the loading port 6 is slidably fitted to the sleeve 8. The cavity 4 has an entrance-side region 4a having a relatively large capacity communicating with the gate 5, and an intermediate region 4 having a relatively small capacity communicating with the region 4a.
b and an inner region 4c having a relatively large capacity and communicating with the region 4b.

In casting an Al-based alloy casting, the following steps are sequentially performed. (A) heating a solid material made of an Al-based hypoeutectic alloy;
Thus, a semi-molten casting material in which a solid phase and a liquid phase coexist is prepared. (B) The casting material is charged into the charging port 6. (C) The pressurized plunger 9 is inserted into the charging port 6, and the pressurized plunger 9 fills the cavity 4 with the casting material at high speed sequentially through the gate 5. (D) By holding the pressure plunger 9 at the end of the stroke, a pressing force is applied to the casting material filled in the cavity 4, and the casting material is solidified under the pressure to obtain a casting.

In the casting method, the Al-based hypoeutectic alloy includes Al-Si-based, Al-Mg-based, Al-Cu-based,
Hypoeutectic alloys such as l-Ca and Al-Ga are applicable.

For example, as the Al-Si hypoeutectic alloy, an alloy having a Si content of less than 11.7% by weight is used, and the Al-Si hypoeutectic alloy is, for example, 6.5% by weight. ≦ Si ≦ 7.5% by weight, Fe ≦ 0.20% by weight, C
u ≦ 0.20% by weight, Mn ≦ 0.10% by weight, 0.40
Wt% ≦ Mg ≦ 0.70 wt%, 0.04 wt% ≦ Ti
≦ 0.20% by weight.

In the above chemical components, Si precipitates Mg ₂ Si by heat treatment and contributes to the improvement of the strength of the casting.
However, when the content of Si is less than 6.5% by weight, the effect of improving the strength is small, while when the content of Si is more than 7.5% by weight, the impact value and toughness of the casting are reduced.

Fe improves the high-temperature strength of the casting and improves the mold,
In particular, it contributes to preventing seizure of the casting material on the mold. This high temperature strength improving mechanism is based on the dispersion strengthening of the AlFeMn intermetallic compound. However, when the Fe content is Fe> 0.20
When the weight% is used, the elongation and toughness of the casting decrease.

Cu precipitates Al ₂ Cu by heat treatment and contributes to the improvement of the strength of the casting. However, when the Cu content is Cu> 0.20% by weight, the corrosion resistance of the casting decreases.

Mn contributes to improving the high-temperature strength of the casting and has a function of agglomerating the AlFe intermetallic compound. However, when the Mn content is Mn> 0.10% by weight, the elongation and toughness of the casting decrease.

Mg contributes to the improvement of the strength of the casting in cooperation with Si as described above. However, when the content of Mg is Mg <
At 0.40% by weight, the effect of improving strength is small.
If it is> 0.70% by weight, the elongation and toughness of the casting decrease.

[0027] Ti contributes to the refinement of crystal grains at the above content .

[0028] In the metal structure of solid material, the shape factor F
Is F ≧ 0.1, the area ratio Ra of the primary crystal α-Al is set to Ra ≧ 80% as described above, and the primary crystal α-Al
Maximum particle diameter d of the is set to d ≦ 300 [mu] m. With this configuration, the fatigue strength of the casting, elongation, thereby improving the toughness and the like. The maximum particle size d of primary α-Al is d>
If the thickness is 300 μm, the fatigue strength of the casting decreases.
You.

[0029] In the case of obtaining a semi-molten material from the solid material, the heating condition is set as follows.

The average temperature rise rate Tv of the solid material is Tv ≧ 0.
2 ° C / sec, soaking degree Δ between inside and outside of semi-solid material
T is ΔT ≦ ± 10 ° C., viscosity μ of the semi-molten material is 0.1 Pa
· Sec ≦ μ ≦ 2000 Pa · sec. By setting the heating conditions in this way, the preparation and handling of the semi-molten material can be performed efficiently, and the casting quality of the casting can be improved. However, if the average heating rate Tv of the solid material is T
When v <0.2 ° C./sec, since it takes a long time to prepare a semi-molten material, the primary crystal α-Al is coarsened and the mechanical properties of the casting are impaired. The optimum range of the average heating rate Tv is Tv ≧ 1.0 ° C./sec. The reason is that, when the average heating rate Tv is Tv <1.0 ° C./sec, the productivity is likely to be reduced, the metal structure is coarsened, and the surface is oxidized.

When the temperature uniformity ΔT between the inside and the outside of the semi-molten material is ΔT> ± 10 ° C., since the viscosity μ of the semi-molten material is partially different, a melt-out portion is generated, This leads to the occurrence of chipping in the filling points and therefore in the casting. The optimum range of the soaking degree is ΔT ≦ ± 3 ° C. The reason is that in such a range, the semi-molten material can be automatically handled, thereby improving the productivity of the casting.

The viscosity μ of the semi-molten material is set to be the same as that at the time of casting. The viscosity μ is μ <0.1 Pa ·
In the case of sec, a melt-out portion is generated and the handling property of the semi-molten material is deteriorated, while the viscosity μ is μ> 2000 Pa ·
At sec, the casting quality of the casting decreases as described above.

The property of the semi-molten material when passing through the gate 5 during casting, that is, the viscosity μ of the semi-molten material is 0.1 Pa · sec ≦ μ ≦ 2000 Pa · sec as described above.
And Reynolds number Re is, as described above, Re ≦ 1
It is set to 500.

In order to improve the casting quality of the casting, a half
Section of mold 1 with Reynolds number Re of molten material
The product expansion rate Rs becomes a problem. Here, the cross-sectional area expansion rate Rs
Means that the cross-sectional area of the gate 5 is S ₀ in FIG.
The cross-sectional area of the inlet-side region 4a and S ₁ in Yabiti 4
When I is represented by Rs = S ₁ / S _0.

The cross-sectional area enlargement ratio Rs is set so that Rs ≦ 10.
It is. When the cross-sectional area expansion rate Rs is set in this manner, the semi-solid
Prevents entrainment of gas by molten material and generation of hot water
be able to. However, the cross-sectional area expansion rate Rs is Rs> 10.
The semi-molten material is ejected from the gate 5
The cavity 4 is injected into the cavity 4 and the filling order is
Since it is the next entrance side area 4a, a hot water boundary is generated.

The optimum range of the cross-sectional area enlargement ratio Rs is 1 ≦ Rs ≦
5 The reason is that such cross-sectional area expansion rate Rs
Because it can be easily realized by the conventional pressure casting equipment.
You. However, when the cross-sectional area enlargement ratio Rs becomes Rs> 5, the actual
Qualitatively for the cross-sectional area of the gate 5 is small Kunar, the gate 5
Solidification of the semi-molten material in the cavity 4
Prior to final solidification of the material, as a result
And the entrance side region 4a and the back region 4
c may cause shrinkage at both thick portions of the casting corresponding to c.
is there. On the other hand, when the cross-sectional area enlargement ratio Rs becomes Rs <1,
The cross-sectional area of the gate 5 is the cross-section of the entrance-side region 4a of the cavity 4.
Because it is almost equal to the product, scrap corresponding to gate 5
Operations such as a decrease in the yield of castings
A business problem arises.

Further, the speed V of the semi-molten material when passing through the gate 5 is 0.5 m / sec ≦ V ≦ 2 as described above.
0 m / sec, and the pressure P on the semi-molten material filled in the cavity 4 is 10 MPa ≦ P
≦ 120 MPa.

Hereinafter, specific examples will be described .

[0039] As solid material consisting of A l-Si based hypoeutectic alloy was selected to have a composition shown in Table 1. In the metal structure of this material, the area ratio Ra of the primary crystal α-Al whose shape factor F is F ≧ 0.1 is Ra = 80%, and the maximum particle size d of the primary crystal α-Al is d = 200 μm Met.

[0040]

[Table 1]

In the mold 1, the sectional area S of the gate 5
₀ and between the cross-sectional area S ₁ of the inlet-side region 4a of the cavity 4
The cross-sectional area enlargement ratio Rs (S ₁ / S ₀ ) that is established in Rs = 4
Set to.

First, the solid material is placed in a heating furnace, and then heated with the average temperature rising rate Tv set to Tv = 1.3 ° C./sec, whereby the soaking degree ΔT between the inside and the outside becomes ΔT
= 6 ° C., and a solid-solid material having a solid phase volume fraction Vf of Vf = 70% was prepared. This solid phase had a metal structure similar to that of the solid material.

The semi-molten material was charged into the charging port 6 of the mold 1, and then the semi-molten material was filled into the cavity 4 at high speed through the gate 5 by the pressure plunger 9. In this case, the moving speed of the pressure plunger 9 is set to about 78 mm / sec, and the speed V of the semi-molten material when passing through the gate 5
Is V = 3 m / sec, viscosity μ is μ = 300 Pa · sec
c, Reynolds number Re was Re = 0.21.

As shown in FIG. 1, the lower position G of the gate 5 in the mold 1, the upper position U1 and the lower position L1 of the entrance-side region 4a of the cavity 4, and the inner region 4c.
By examining the filling behavior of the semi-molten material by measuring the temperature rise start points at the upper position U2 and the lower position L2, the filling order is U2, almost simultaneously with G → L1 → U1 → L2, It has been confirmed that it is ideal for avoiding the occurrence of casting defects.

The pressurizing plunger 9 is held at the end of the stroke to apply a pressing force to the semi-molten material filled in the cavity 4, and the semi-molten material is solidified under the pressure to form a casting A _7.
I got In this case, the pressure P for the semi-molten material is P =
It was 30 MPa, and it was confirmed that burrs generated on the divided surface 10 of the mold 1 were extremely small .

FIG . 2 shows the time and processing in the casting operation.
Pressure plunger stroke and load on semi-solid material
Shows the relationship with pressure. In the figure, line a represents the stroke,
Lines b correspond to the above-mentioned pressures. From FIG.
The semi-molten material in a stroke end near the pressure plunger 9
It can be seen that the pressing force for this suddenly increases. This rise open
Pressure of Hajimeji is 10 MPa, to obtain which castings A ₇
Is the minimum pressing force for

[0047] Figure 3 is a photomicrograph showing the metal structure of the casting A ₇ obtained by the casting method (100-fold).
In the figure, it can be seen that the light gray granular portion occupying most of the region is primary α-Al, and the maximum particle size d is d = 200 μm. The reason why such a metal structure is obtained is that the maximum particle size d of the primary crystal α-Al in the solid phase of the semi-molten material is d = 200 μm, and the primary crystal α-Al crystallized from the liquid phase is This is because the phase is subjected to a shearing force when passing through the gate 5 and solidified under pressure, so that the miniaturization is achieved. The area ratio Ra of the shape factor F is F ≧ 0.1 primary crystal alpha-Al is Ra = 98%, the fatigue strength of the casting A ₇ By setting in this way, to improve the elongation and toughness Can be. In addition, this casting A _7, as apparent from FIG. 3, cold shut, no generation of pores due entrainment gas and also chipping due to unfilled semi-molten material into the cavity 4 not intended, therefore, the casting a ₇ was found to have excellent casting quality.

Next, by changing the moving speed of the pressure plunger 9, the speed V and Reynolds number Re of the semi-molten material when passing through the gate 5 are changed, and the other conditions are set to be the same as those of the casting method. Example castings A ₈ and A ₉ and comparative example castings B ₁₂ and B ₁₃ were cast.

[0049] Table 2, the castings B _12, B ₁₃ by casting A ₇ to A ₉ and Comparative Examples according to the embodiment, showing the relationship between the velocity V and the Reynolds number Re.

[0050]

[Table 2]

FIG. 4 shows the relationship between the velocity V of the semi-molten material when passing through the gate 5 and the viscosity μ of the semi-molten material when passing through the gate. In the figure, the line c corresponds to the case where the Reynolds number Re when passing through the gate 5 is Re = 1500,
Therefore, a region including the line c and above the line c is a laminar flow region, and a region below the line c is a turbulent flow region.

FIG. 5 shows the relationship between the velocity V of the semi-molten material passing through the gate 5 and the pressure P applied to the semi-molten material filled in the cavity 4.

As mentioned above, from the viewpoint of improving the casting quality, the speed V is set to 0.5 m / sec ≦ V ≦ 20 m / sec.
c, the viscosity μ is 0.1 Pa · sec ≦ μ ≦ 2000P
a · sec, the Reynolds number Re is preferably Re ≦ 1500, and the pressure P is preferably 10 MPa ≦ P ≦ 120 MPa. From Table 2, FIG. 4 and FIG. 5 , the casting A according to the embodiment is shown.
₇ in to A ₉ it can be seen that the conditions described above are met.

[0054] In the casting B ₁₂ according to the comparative example, since the speed V is below the lower limit value (0.5 m / sec), the filling order of the semi-molten material to the cavity 4, in FIG. 1, G → L1 → U1 → L2 → U2, and as a result, the upper position U2 in the deep region 4c of the cavity 4
The unfilled portion is generated in the semi-molten material, chipping had occurred in the casting B ₁₂ correspondingly. In the casting B ₁₃ according to the comparative example, since the speed V is higher than the upper limit (20 m / sec), the filling order of the semi-molten material into the cavity 4 is G → U2 → L2 → L1 → U1, and consequently, the semi-molten material partially solidified earlier at the inlet side region 4a and the rear region 4c of the cavity 4, cold shuts had occurred in the casting B ₁₃ correspondingly. The occurrence of pores due to entrainment of gas in the casting B ₁₃ for semi-molten material is injected into the cavity 4 becomes jet flow was observed.

For comparison, the castings B ₁₄ and B ₁₅ were cast by the above-mentioned casting method while changing only the conditions shown in Table 3 . Both castings B _14, B ₁₅ is also shown in Figure 4.

[0056]

[Table 3]

[0057] In the casting B ₁₄ according to the comparative example, chipping was observed due to the high viscosity of the semi-molten material. In casting B ₁₅ according to the comparative example, due to the low viscosity of the semi-molten material entrainment of gas by a turbulent flow, thus the occurrence of pores was observed.

For comparison, the pressure P was set to P = 90MP.
Set a, by the casting method by setting other conditions similarly to the above, Example casting B ₁₂ by casting A ₁₀ to A ₁₂ and the Comparative Example corresponds to the casting A ₇ to A ₉ by, B
Castings B ₁₆ and B ₁₇ corresponding to ₁₃ were cast. Castings A
₁₀ to A ₁₂ and B _16, B ₁₇ is 4, is shown in Figure 5, it was confirmed that the casting quality corresponding to each of the casting A ₇ to A ₉ and B _12, B _13. That is, rather than the occurrence of casting defects in casting A ₁₀ to A _12, whereas, castings B ₁₆
The chipping occurs and also the occurrence of cold shuts and pores in the casting B ₁₇ was observed.

[0059] Table 4 shows the types of various conditions and casting defects when casting the castings B ₁₈ .about.B ₂₀ according to a comparative example. Under these conditions, the area ratio Ra of the primary crystal α-Al and the viscosity μ of the semi-molten material outside the range of the present invention are out of the range of the present invention.

[0060]

[Table 4]

[0061]

According to the first aspect of the present invention, the aforementioned
By using a specific solid material urchin, excellent
A casting having casting quality can be obtained.

According to the second aspect of the present invention, by specifying the viscosity μ and Reynolds number Re of the casting material when passing through the gate as described above, high quality and excellent quality without generation of pores and hot junctions can be obtained. A having excellent mechanical properties
An l-type alloy casting can be obtained.

According to the third aspect of the present invention, by specifying the speed V and the pressing force P of the casting material at the time of passing through the gate as described above, in addition to the above-described effects, the productivity and operation of the Al-based alloy casting can be achieved. The above problems can be avoided .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a pressure casting apparatus.

FIG. 2 shows time, stroke and half of the pressure plunger
It is a graph which shows the relationship with the pressing force with respect to a molten material.

3 is a micrograph showing a cast metal organizations.

FIG. 4 shows velocity V and viscosity of semi-molten material when passing through a gate .
6 is a graph showing a relationship with a degree μ.

FIG. 5 shows the velocity V of the semi-molten material when passing through the gate,
4 is a graph showing a relationship between a pressure P and a pressure applied to a semi-molten material.
You.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 4 Cavity 5 Gate 6 Loading inlet 9 Pressurized plunger

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-57-206560 (JP, A) JP-A-3-75329 (JP, A) JP-A-2-141543 (JP, A) 47951 (JP, B2) JP-B-53-34564 (JP, B2) JP-B-48-8694 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) B22D 17/00 B22D 18 / 02 C22C 1/02 501 C22C 1/02 503

Claims (3)

(57) [Claims] A solid material comprising an Al-based hypoeutectic alloy is added.
Heated, semi-solid casting material in which solid and liquid phases coexist
And then cast under pressure using the casting material
In the casting method, wherein the solid material is
The area ratio Ra of primary α-Al in which the number F is F ≧ 0.1 is represented by R
A method for casting an Al-based alloy casting, characterized by using a material set to a ≧ 80% . 2. A method before Symbol casting material, its viscosity mu 0.1P
2. The casting method for an Al-based alloy casting according to claim 1, wherein the Al-based alloy casting is passed through a gate of a mold under the conditions of a.sec.ltoreq..mu..ltoreq.2000 Pa.sec. 3. A speed V of the casting material when passing through the gate is 0.5 m / sec ≦ V ≦ 20 m / sec, and a pressure P applied to the casting material filled in a cavity of the mold is 10 MPa ≦. a P ≦ 120 MPa, method of casting an Al-based alloy casting according to claim 1 or 2 wherein.