JP4155509B2 - Aluminum alloy for casting, casting made of aluminum alloy and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an aluminum alloy for casting suitable for die casting and the like, an aluminum alloy casting, and a method for producing the same.
[0002]
[Prior art]
In recent years, there has been a rapid shift from conventional cast iron products to lightweight aluminum alloy products due to demands for weight reduction of various products. This weight reduction improves the performance of various devices and the like, and particularly in the case of automobiles, the environment is improved by improving the fuel consumption due to the weight reduction.
By the way, aluminum alloy products are manufactured through various methods and processes such as casting, forging, and cutting, but in mass production that requires cost reduction, they are often manufactured by a die casting method. According to the die casting method, cutting and the like can be greatly reduced, and a product with high precision and a beautiful casting surface can be obtained in a short cycle time. Casting becomes a problem when performing this die casting. That is, it is important how to mass-produce stable quality aluminum alloy castings while eliminating casting defects such as casting cracks. From this point of view, an Al—Si-based aluminum die casting alloy (for example, JIS ADC12) that has excellent castability has been used so far.
[0003]
However, in the case of an aluminum alloy casting made of an Al—Si alloy, the ductility is very small, regardless of strength. For this reason, it is difficult to apply the casting to a member that requires high strength and high ductility. Therefore, with Al-Si alloys, the application range is limited, and it is difficult to sufficiently meet recent needs.
Therefore, it is conceivable to use an Al-Mg alloy instead of an Al-Si alloy, but the conventional Al-Mg alloys have poor castability, and generally speaking, casting such as casting cracks on the casting surface. It was easy to produce a defect. In particular, in the case of a casting or the like having a complicated shape, a thin portion, or a large cross-sectional change, a casting crack is likely to occur on the surface. Such a casting crack is not preferable because the strength of the member is greatly reduced by the notch effect and the appearance of the member is impaired.
Therefore, Patent Document 1 below proposes an Al—Mg-based casting aluminum alloy that can obtain a casting having high strength, high toughness and stable quality. Specifically, an Al—Mn—Mg—Ti—Sb alloy is disclosed therein.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-330202
[Problems to be solved by the invention]
However, in the case of the above-mentioned Patent Document 1, by adding Sb or the like, Mn is forcibly dissolved in a portion where the cooling rate at the time of casting is slow and crystallization of the primary crystal Al ₆ Mn is suppressed. The purpose is to obtain a cast structure with a stable quality as a whole.
However, the above-mentioned Patent Document 1 does not mention any casting cracks. Therefore, when the present inventors actually performed die casting of a casting having a large cross-sectional change using this alloy, many casting cracks were generated on the surface of the obtained casting.
[0006]
The present invention has been made in view of such circumstances. That is, an object of the present invention is to provide an aluminum alloy for casting that is a high-strength, high-ductility Al—Mg-based alloy that can significantly suppress the occurrence of casting cracks even when die casting is performed. It is another object of the present invention to provide an aluminum alloy casting using the casting aluminum alloy and a method for producing the same.
[0007]
[Means for Solving the Problems and Effects of the Invention]
The present inventor has intensively studied to solve this problem, and as a result of repeating various systematic experiments, Al-Mg-Mn-Fe-, which is excellent in castability and has a high strength and high ductility even in an as-cast state. The inventors discovered a Ti alloy and newly discovered that casting cracks can be further suppressed by adding an appropriate amount of Sb to the alloy. This has been further developed to complete the present invention.
(Aluminum alloy for casting)
That is, the casting aluminum alloy of the present invention has Mg of 2 to 6% and Mn: 0.3 to 1.2% when the whole is 100% by mass (hereinafter simply referred to as “%”). , Fe, Ni or Co, one or more total: 0.5 to 1.1%, Ti, Zr, V, Cr or B one or more total: 0.01 to 0.5% ,
Sb: 0.01 to 0.5% is included, the balance is made of Al and inevitable impurities, and the replenishability of the residual liquid phase during casting is excellent.
[0008]
The Al—Mg—Mn—Fe (Ni, Co) —Ti (Zr, V, Cr, B) alloy developed by the present inventors itself has high strength and high ductility and excellent castability. It is. And when it is used and die-casting, a big casting crack etc. do not arise. However, even with this alloy, it has been found that fine casting cracks can occur on the surface in the case of castings whose cross-sectional shape changes greatly. Specifically, it is the back surface of the rib or the root. For this reason, if the alloy is used as it is, the shape of the cast member that can be applied is limited, and the degree of design freedom is reduced, the casting method is limited, die casting cannot be performed, and the yield may be deteriorated.
Therefore, while increasing the degree of design freedom of castings, the casting conditions that can be cast are expanded to facilitate casting with existing facilities, etc. to reduce manufacturing costs, and casting that can supply stable quality castings even during mass production. Therefore, the present invention has succeeded in solving this problem by adding an appropriate amount of Sb to the above alloy. The reason for this is not necessarily clear, but it can be considered as follows. In the following description, the case of die casting in which high castability is required will be mainly described as an example.
[0009]
First, when the conventional Al-Mg-Mn alloy is die-cast, the causes of casting cracks on the casting surface are that it solidifies in an iterative manner, the amount of crystallized compounds that form a residual liquid phase, and those As a result, the brittle temperature range in the semi-solidified state is wide.
In order to improve this, in the casting aluminum alloy of the present invention, the amount of crystallized compounds is increased by adding an appropriate amount of one or more of Fe, Ni or Co (hereinafter simply referred to as “Fe etc.” as appropriate). ing. Further, by adding an appropriate amount of one or more of Ti, Zr, V, Cr or B (hereinafter simply referred to as “Ti etc.” as appropriate), the primary crystal form is made spherical and the brittle temperature range is narrowed. However, even though this can prevent large casting cracks, it is not sufficient for suppressing and preventing fine casting cracks.
[0010]
Next, when this fine casting crack was observed, it became clear that the residual liquid phase that would normally flow into the cracked part caused by solidification shrinkage and did not sufficiently reach the casting surface. It was. As measures to improve this, it was considered effective to increase the amount of residual liquid phase or increase the fluidity of the residual liquid phase. However, increasing the amount of residual liquid phase means that crystallized compounds (Al ₆ Mn, Al ₆ (Mn, Fe), Al ₃ Fe) that crystallize after the primary crystal (α phase: α-Al) crystallizes. Etc.). This increase in the crystallized compound leads to a decrease in toughness and does not conform to the object of the present invention of a highly ductile aluminum alloy for casting. Therefore, it is not preferable to increase the residual liquid phase after primary crystallization by increasing the content of Fe or the like or Mn beyond the above range of the present invention.
[0011]
Therefore, it was considered effective to increase the fluidity of the residual liquid phase, and when the present inventor tried various elements effective in improving the fluidity, the inventors finally found out that Sb has the effect. By adding an appropriate amount of this Sb, the fluidity of the residual liquid phase is improved, the residual liquid phase is smoothly replenished to the crack generation part, the crack is filled, and the occurrence of the casting crack is remarkably suppressed. It is thought.
[0012]
(Aluminum alloy castings)
This invention can be grasped | ascertained also as an aluminum alloy casting of the desired shape cast using it other than the said aluminum alloy for casting.
That is, in the present invention, the total of Mg: 2 to 6%, Mn: 0.3 to 1.2%, and any one or more of Fe, Ni, or Co when the whole is 100%: 0.5 -1.1%, including one or more of Ti, Zr, V, Cr or B: 0.01-0.5%, Sb: 0.01-0.5%, with the balance being Al It may be a casting made of an aluminum alloy for casting, which is characterized in that the residual liquid phase is replenished during casting and there is almost no surface cracking.
[0013]
(Production method of aluminum alloy castings)
Furthermore, this invention can be grasped | ascertained also as a manufacturing method of the aluminum alloy casting.
That is, in the present invention, the total of Mg: 2 to 6%, Mn: 0.3 to 1.2%, and any one or more of Fe, Ni, or Co when the whole is 100%: 0.5 -1.1%, including Ti, Zr, V, Cr or B at least one total: 0.01-0.5%, Sb: 0.01-0.5%, the balance being Al an injection step of injecting a melt of an aluminum alloy consisting of unavoidable impurities at a high speed into a mold, and a solidifying step of rapidly solidifying the molten metal injected into the template, mostly surface cracks residual liquid phase is supplied to the casting A method for producing an aluminum alloy casting characterized in that an aluminum alloy casting can be obtained.
[0014]
By the way, “high strength” in the present invention means, for example, that 0.2% proof stress is 120 MPa or more, and “high ductility” means, for example, that elongation at break is 13% or more. To do. “Castability” is a concept that includes not only the meltability and releasability of the molten metal, but also the rate of occurrence of casting cracks and shrinkage cavities (porosity). This means the degree of casting cracking. However, it is difficult to unconditionally define the extent of this casting crack. This is because whether or not casting cracks are generated varies greatly depending on the casting shape and casting conditions. For this reason, even if a casting crack becomes a level which is practically no problem by using the aluminum alloy for casting of the present invention, it should be noted that there is not necessarily no fine casting crack.
[0015]
“Casting” as used in the present invention is not limited to die casting. Ordinary mold casting, high pressure casting and the like may be included. However, as can be seen from the above-described casting crack suppression mechanism, the casting aluminum alloy of the present invention is injected into the mold cavity at a high speed with a plunger or the like, and the molten alloy is pressurized, It is particularly suitable for die casting that is rapidly solidified.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail with reference to embodiments. In the following description, the aluminum alloy for casting will be mainly described. However, it should be noted that the contents appropriately correspond to the aluminum alloy casting of the present invention and the manufacturing method thereof.
(1) Alloy composition (1) Mg
Mg is an element that dissolves in an Al matrix and improves the mechanical strength (for example, tensile strength and proof stress) of the aluminum alloy and also affects the ductility.
When there is too little Mg, sufficient mechanical strength cannot be obtained. On the other hand, too much Mg is not preferable because a large amount of coarse crystals start to crystallize, leading to deterioration of ductility. Therefore, the lower limit of Mg is preferably 2%, more preferably 4%, and the upper limit is preferably 6%, further 5%. In particular, Mg is preferably 2 to 6%.
[0017]
▲ 2 ▼ Mn
Similar to Mg, Mn is an element that forms a solid solution in an Al matrix, or forms a compound with Al or Fe and precipitates finely in the matrix to improve the mechanical strength of the aluminum alloy.
If the amount of Mn is too small, sufficient mechanical strength cannot be improved. On the other hand, if the amount of Mn is too large, a coarse crystallized product is crystallized, resulting in a decrease in ductility. Therefore, the lower limit of Mn is preferably 0.3%, more preferably 0.4%, and the upper limit is suitably Mn ≦ −0.1Mg + 1.2.
[0018]
(3) Fe, such as Fe, Ni or Co is an element that crystallizes a compound at the time of solidification and suppresses casting cracks accompanying solidification shrinkage and thermal shrinkage of the primary crystal.
If the amount of Fe or the like is too small, a residual liquid phase sufficient to fill a casting crack generated on the surface cannot be obtained, and the casting crack cannot be sufficiently suppressed. On the other hand, too much Fe or the like is not preferable because it causes a decrease in toughness due to an increase in the amount of crystallized compounds and crystallization of coarse crystals. Therefore, the lower limit of the total of any one or more of Fe and the like is preferably 0.5%, more preferably 0.6%, and the upper limit is preferably 1.1%, more preferably 1%. In particular, Fe or the like is suitably 0.6 to 1%.
In addition, Mn is also related to the above-described casting crack inhibiting mechanism of the present invention, and coexistence of Fe and the like with Mn is necessary to secure a residual liquid phase after crystallization of primary crystals and the like. In addition to the amount of Mn, the amount of Fe, etc., the total of both is suitable at 1% or more.
[0019]
(4) Ti, such as Ti, Zr, V, Cr, or B is an element effective in suppressing casting cracks by forming a primary phase α-phase nucleation site and spheroidizing the primary crystal. That is, by adding Ti, the crystal grain size of primary Al decreases, and the solid-liquid flow state is maintained up to the high solid phase ratio side (that is, the fluidity of the residual liquid phase is ensured). And it is thought that the brittle temperature range becomes narrow, the generation time of cracking stress due to solidification shrinkage shifts to the low temperature side, and cast cracking resistance is improved. In addition, Ti or the like refines the cast structure, and is effective in improving ductility and strength.
[0020]
If the amount of Ti or the like is too small, these effects cannot be obtained sufficiently, and if the amount of Ti or the like is too large, a coarse crystallized product (Al ₃ Ti or the like) starts to crystallize, leading to a decrease in ductility. Therefore, the lower limit of the total of at least one of Ti and the like is preferably 0.01%, more preferably 0.1%, and the upper limit is preferably 0.5%, more preferably 0.25%. In particular, Ti or the like is preferably 0.1 to 0.25%.
[0021]
In particular, B exhibits a great effect on the refinement of crystal grains in the presence of Ti. If the amount of B is too small, the effect is not sufficiently exhibited. Conversely, even if the amount of B is increased, the improvement of the effect cannot be expected so much. Therefore, the lower limit of B is preferably 0.01%, more preferably 0.02%, and the upper limit thereof is preferably 0.05%, further 0.04%. In particular, B is preferably 0.01 to 0.05%. B is economical when added as a titanium boride such as TiB ₂ in addition to the case where B is added alone.
[0022]
Cr, like Mg and Mn, is an element that improves the mechanical strength by being dissolved in an aluminum matrix. If the amount of Cr is too small, the effect is not sufficiently exhibited. Conversely, if the amount of Cr is too large, a coarse crystallized product is crystallized, resulting in a decrease in ductility. Therefore, the lower limit of Cr is preferably 0.1%, more preferably 0.2%, and the upper limit is preferably 0.7%, more preferably 0.5%. In particular, Cr is preferably 0.2 to 0.5%.
[0023]
(5) Sb
As described above, Sb is an element effective for improving the wettability between the crystallized solid phase and the liquid phase finally solidified and enhancing the fluidity of the residual liquid phase.
If the amount of Sb is too small, such an effect cannot be obtained sufficiently. If the amount of Sb is too large, on the contrary, the fluidity of the residual liquid phase is lowered and the molten metal is not sufficiently supplied to the cracked portion, and the casting crack is not generated. It can easily occur. On the other hand, when Sb is excessive, the amount of the crystallized compound increases, leading to a decrease in toughness.
Therefore, the lower limit of Sb is preferably 0.01%, more preferably 0.02%, and the upper limit thereof is preferably 0.5%, further 0.3%. In particular, Sb is preferably 0.02 to 0.3%.
[0024]
▲ 6 ▼ Be
Be alone or in the coexistence with Ti or the like is effective in suppressing the oxidation of the molten metal, and suppresses the oxidative consumption of Mg during melting. If the amount of Be is too small, the effect is not sufficiently exhibited. Conversely, even if Be is increased, the improvement of the effect cannot be expected so much, which is uneconomical. Therefore, the lower limit of B is preferably 0.001%, more preferably 0.005%, and the upper limit thereof is preferably 0.01%, further 0.008%. Particularly, Be is preferably 0.001 to 0.01%.
[0025]
(7) Inevitable impurities The type and content of inevitable impurities are not limited as long as they do not adversely affect the properties of the aluminum alloy. However, the present inventor has found that the castability, strength, or ductility of the aluminum alloy is improved by controlling the contents of Si and Cu, which are inevitable impurities. That is, it is preferable that Si, which is an inevitable impurity, is 0.5% or less, Cu is 0.3% or less, and Zn is 1% or less with respect to 100% as a whole. Si is an inevitable impurity contained in aluminum ingots, etc. If it exceeds 0.5%, Mg ₂ Si precipitates in the matrix by natural aging, and the mechanical properties of the aluminum alloy change over time. It is not preferable. Cu is an element that promotes casting cracking and inhibits corrosion resistance. In particular, when the aluminum alloy casting of the present invention is used as a structural member, it is preferably 0.3% or less. Zn is also an element that promotes casting cracking, and is preferably made 1% or less.
[0026]
(8) Others The present invention is a casting aluminum alloy having the above component composition, but may contain other elements in appropriate amounts within a range not impairing its high strength, high ductility and cast cracking resistance. . For example, Mo may be contained in order to suppress generation of noro accompanying oxidation of the molten Al-Mg alloy. At this time, the Mo amount is preferably 0.05 to 0.3%. If Mo is less than 0.05%, the effect of inhibiting oxidation is not sufficient, and if it exceeds 0.3%, a coarse crystal is crystallized, resulting in a decrease in ductility.
[0027]
(2) Manufacturing method The casting aluminum alloy of the present invention is naturally suitable for casting, but the casting method is not limited. However, considering the application of aluminum alloy castings to mass-produced products with thin walls, complex shapes, etc., most of them are die-cast. And the aluminum alloy for casting of this invention exhibits the stable castability which hardly produces a casting crack etc., and the high intensity | strength and high ductility which are impossible with an Al-Si type alloy, even when die-casting.
[0028]
By the way, in such die casting, molten alloy is rapidly supplied to a cavity of a set mold from a plunger or the like and rapidly solidified while being pressurized. Usually, it is performed almost automatically or continuously by a die-casting machine or the like, and has high mass productivity.
[0029]
The die casting conditions are substantially defined by, for example, casting pressure, injection temperature, injection speed (or molten metal injection time), cooling speed, and the like. The casting pressure is, for example, 10 to 100 MPa, and further 20 to 80 MPa. The high-speed injection speed is, for example, 0.8 to 10 m / sec, and further 2 to 10 m / sec. In terms of the molten metal pouring time, it is, for example, 200 msec or less, and further 10 msec or less. Strictly speaking, the cooling rate varies depending on the casting site, and thus cannot be specified uniformly. However, the cooling rate is, for example, 20 ° C./sec or more, further 50 ° C./sec or more at the latest.
[0030]
In the case of die casting, injection of molten metal into the mold can be considered in two stages. There are a product part injection process for filling the product part of the mold with the molten metal and a plan part injection process for filling the design part at the entrance of the product part with the molten metal. The product part injection process is performed at a high speed as described above, but the plan part injection process is performed at a relatively low speed with an injection speed of 0.1 to 1 and an injection time of about 1000 to 4000 msec. Therefore, the above description relates to the product part injection process, and the injection time of the molten metal is the time from the start of supplying the molten metal to the product cavity of the mold until the inside of the cavity is filled with the molten metal. is there. “High speed” in the injection step of the production method of the present invention means, for example, that the injection time is 500 msec or less.
[0031]
In addition, the injection | pouring process and solidification process said by the manufacturing method of this invention are not limited to die-casting. Moreover, both processes are not necessarily distinguished clearly, and may be performed continuously or overlappingly. For example, when considering die casting, the solidification process is often partially started before the injection process is completed. Moreover, although it is theoretically said that substantial pressurization of the molten metal is started after the completion of the injection step, it may be considered that the pressure is applied from the injection step. In the case of the present invention, pressurization of the molten metal is important for suppressing casting cracks. This is because when the molten metal is in a pressurized state, replenishment of the residual liquid phase to the cracked portion caused by solidification shrinkage is promoted.
[0032]
(2) Applications The casting aluminum alloy and aluminum alloy casting of the present invention may be subjected to heat treatment such as solution treatment or aging treatment after casting, but excellent strength and ductility even in an as-cast state without heat treatment. Demonstrate. Therefore, an aluminum alloy casting having high strength and high ductility can be obtained at low cost. In addition, if it is a die-cast product, the cycle time required for casting is short, processing after casting is almost unnecessary, and the cost of aluminum alloy castings can be further reduced.
[0033]
Various uses of the aluminum alloy casting of the present invention are conceivable. Examples thereof include the following. In the field of automobiles and motorcycles, body structural members, chassis members, wheels, space frames, steering wheels (core metal), seat frames, suspension members, transmission cases, pulleys, oil pans, shift levers, instrument panels, doors Impact panels, intake surge tanks, pedal brackets, front shroud panels, etc.
[0034]
【Example】
Next, the present invention will be described in more detail with reference to examples according to the present invention.
(Production of test piece)
Six test pieces (aluminum alloy castings) having a composition of Al-4.5% Mg-0.3% Mn-0.7% Fe-0.15% Ti-x% Sb (unit: mass%) Manufactured by die casting. The Sb amount of each test piece was 0%, 0.02%, 0.1%, 0.3%, 0.5%, 0.75%, or 1%, respectively.
[0035]
Die casting was performed using a vertical die casting machine. That is, various molten metals prepared to the above composition were injected by pressure into the mold cavity with a plunger (φ40 mm) (injection step) and then solidified at a cooling rate of about 100 ° C./second (solidification step). The casting conditions at this time were casting pressure: 64 MPa, injection (plunger) speed: 0.6 m / s, injection (melting) temperature: liquidus temperature + 10 ° C. The mold temperature was set to 50 to 100 ° C.
[0036]
The shape of the manufactured test piece is shown in FIG. The test piece has a width of 40 × height 70 × thickness 2 mm connected to the gate, a width 40 × height 65 × thickness 10 mm of the thickness extending from the thin plate, and a thickness protruding from the center surface of the thin plate. It consists of ribs with a width of 2 x height of 70 x height of 8 mm that bridge the plate part to the gate. And the back surfaces of the thin plate portion and the thick plate portion are flush with each other.
[0037]
(Observation and measurement)
It was examined by color check whether or not casting cracks occurred on the flat surface of each test piece (surface which is flush with the thin plate portion and the thick portion on the opposite side of the rib). The result is shown in FIG. Red and thin streaks indicate the occurrence of cracks.
Further, on this flat surface, the depth of the casting crack at a position of 50 mm in the height direction from the gate was measured by structure observation. The result is shown in FIG.
[0038]
(Evaluation)
As apparent from FIGS. 2 and 3, it was found that cracks occurred on the back side (on the flat surface) of the thin rib whose cross-sectional shape greatly changed. And the addition of Sb suppresses the generation of cracks, and is particularly effective when the amount of Sb is 0.02 to 0.5%, 0.05 to 0.3%, or even around 0.1%. It became clear.
[0039]
(Strength and ductility)
A plate-shaped casting having a thickness of 2 mm, a width of 5 mm, and a length of 70 mm was prepared using a vertical die casting machine with the above-described composition that differs only in the Sb amount under the same die casting conditions as in Example 1, and the parallel part was 15 mm. A flat plate tensile test piece having a width of 5 mm and a flat surface as it was cast was subjected to a tensile test. All specimens are as-cast. When 0.2% proof stress and breaking elongation of each of these test pieces were examined, the 0.2% proof stress was 140 to 150 MPa, and the breaking elongation was 16 to 10%. Incidentally, the elongation when 1% Sb was added was 13% or less.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the shape of a test piece for casting crack evaluation.
FIG. 2 is a photograph showing a color check of a casting crack examined for each test piece.
FIG. 3 is a graph plotting cast crack depths examined for each test piece.

Claims (9)

When the total is 100% by mass (hereinafter simply referred to as “%”),
Magnesium (Mg): 2-6%
Manganese (Mn): 0.3-1.2%
Total of one or more of iron (Fe), nickel (Ni) or cobalt (Co): 0.5 to 1.1%,
Total of one or more of titanium (Ti), zirconium (Zr), vanadium (V), chromium (Cr) or boron (B): 0.01 to 0.5%,
Antimony (Sb): including 0.01 to 0.5%,
The balance consists of aluminum (Al) and inevitable impurities,
An aluminum alloy for casting characterized by excellent replenishability of the residual liquid phase during casting. The aluminum alloy for casting according to claim 1, wherein the total amount of Mn and Fe is 1% or more. Furthermore, the aluminum alloy for casting of Claim 1 or 2 containing beryllium (Be): 0.001-0.01% when the whole is 100%. The aluminum alloy for casting according to any one of claims 1 to 3, wherein a 0.2% proof stress is 120 MPa or more and a breaking elongation is 13% or more in an as-cast state in which heat treatment is not performed after casting. When the whole is taken as 100%, Mg: 2 to 6%, Mn: 0.3 to 1.2%, a total of any one or more of Fe, Ni or Co: 0.5 to 1.1%, Total of any one or more of Ti, Zr, V, Cr or B: 0.01 to 0.5%, Sb: 0.01 to 0.5%, the balance consists of Al and inevitable impurities,
A casting made of an aluminum alloy for casting, wherein the residual liquid phase is replenished during casting and there is almost no surface cracking. The casting made of an aluminum alloy for casting according to claim 5, wherein the casting is made by die casting. When the whole is taken as 100%, Mg: 2 to 6%, Mn: 0.3 to 1.2%, a total of any one or more of Fe, Ni or Co: 0.5 to 1.1%, A total of at least one of Ti, Zr, V, Cr or B: 0.01 to 0.5%, Sb: Aluminum containing 0.01 to 0.5%, the balance being Al and inevitable impurities An injection process for injecting molten alloy into the mold at a high speed;
A solidification step of rapidly solidifying the molten metal injected into the mold,
A method for producing an aluminum alloy casting, characterized in that a residual liquid phase is replenished during casting to obtain an aluminum alloy casting having almost no surface cracks. The said injection | pouring process and / or the said solidification process are the manufacturing methods of the aluminum alloy casting of Claim 7 performed by pressurizing the said molten metal at 10-100 Mpa. The said solidification process is a manufacturing method of the aluminum alloy casting according to claim 7, wherein a cooling rate of the molten metal poured into the mold is 20 ° C / second or more.

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