Casting forming method of aluminum alloy with high thermal cracking tendency

Abstract

The invention belongs to the technical field of aluminum alloy casting, and relates to a casting forming method of an aluminum alloy with high thermal cracking tendency. The method comprises the following steps: adding refined powder into an aluminum alloy melt, and uniformly dispersing to obtain a mixed melt; the refined powder is micron-sized Ti powder embedded with nano-sized TiX powder, and X is selected from at least one of C and N; the mixed melt is cooled to be in a solid-liquid mixed state, aluminum alloy slurry is obtained, and the solid content of the aluminum alloy slurry is 40%-50%; and the aluminum alloy slurry is subjected to die-casting forming, and the aluminum alloy casting is obtained. By means of the preparation method, cracks of the aluminum alloy casting with the high thermal cracking tendency can be effectively eliminated, and the strength and plasticity of the casting are synchronously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy casting, and particularly relates to a casting method for an aluminum alloy with a high thermal cracking tendency. Background Art

[0002] Casting is one of the common forming methods for aluminum alloys. It has the characteristics of being able to directly form complex shapes and being low-cost. It is widely used in transportation, defense equipment, communications, consumer electronics, household appliances and other fields. However, the casting process is only suitable for specially developed casting aluminum alloys, including A356, A380, etc. The mechanical properties of these materials are relatively limited and cannot fully meet the application requirements. High-strength aluminum alloys such as 2618 and 7075 developed for forging processes have higher mechanical properties, but have a higher tendency to hot cracking during casting. Direct casting will produce hot cracks, reduce the quality and performance of the casting, and even cause the casting to be scrapped.

[0003] In order to eliminate the casting cracks of aluminum alloys with high thermal cracking tendency, Al-5Ti-1B master alloy, nano-TiB 2 Particles or rare earth elements are added to the alloy melt to refine the Al grains and reduce the thermal cracking tendency of the alloy, but the above methods have limitations. Al-5Ti-1B is easily poisoned by strengthening elements such as Zr and Sc in high-strength aluminum alloys, and is prone to segregation and sedimentation when kept at high temperature for a long time, thus losing the ability to refine the grains. Nano-TiB 2 The particles tend to agglomerate, which reduces the refining effect; rare earth elements are expensive and their effects are difficult to control. In addition, the above methods will reduce the plasticity of the casting. Summary of the invention

[0004] In order to solve the technical problem of casting cracks in aluminum alloys with high thermal cracking tendency, the present invention provides a casting method for aluminum alloys with high thermal cracking tendency, which can effectively eliminate cracks in aluminum alloy castings with high thermal cracking tendency and simultaneously improve the strength and plasticity of the castings.

[0005] In order to solve the above technical problems, the present invention provides a casting method for an aluminum alloy with a high thermal cracking tendency, comprising the following steps:

[0006] Adding refined powder to the aluminum alloy melt and dispersing it evenly to obtain a mixed melt; the refined powder is micron-sized Ti powder inlaid with nano-sized TiX powder, and the X is selected from at least one of C and N;

[0007] Cooling the mixed melt to a solid-liquid mixed state to obtain an aluminum alloy slurry, wherein the solid content of the aluminum alloy slurry is 40% to 50%;

[0008] The aluminum alloy slurry is die-casted to obtain an aluminum alloy casting.

[0009] Optionally, the nano-scale TiX powder is embedded on the surface or inside of the micro-scale Ti powder;

[0010] The average particle size of the nano-scale TiX powder is 40-60 nm, and the average particle size of the micron-scale Ti powder is 40-60 μm.

[0011] Optionally, the mass ratio of the nano-sized TiX powder to the micron-sized Ti powder is 1:(5-20).

[0012] Optionally, the amount of the refined powder added is 0.1% to 0.5% of the mass of the aluminum alloy melt.

[0013] Optionally, adding refined powder to the aluminum alloy melt comprises the following steps:

[0014] The refined powder is wrapped with aluminum foil, and then the refined powder wrapped with aluminum foil is pressed into the aluminum alloy melt through a bell jar, the adding temperature is 760-800° C., stirring is performed for 3-5 minutes, and heat preservation is performed for 10-20 minutes.

[0015] Optionally, cooling the mixed melt to present a solid-liquid mixed state comprises the following steps:

[0016] The mixed melt is cooled down under eccentric rotation to present a solid-liquid mixed state, the rotation rate of the eccentric rotation is 100 to 200 revolutions per minute, and the rotation time of the eccentric rotation is 1 to 3 minutes.

[0017] Optionally, die-casting the alloy slurry to obtain an aluminum alloy casting comprises the following steps:

[0018] The aluminum alloy slurry is filled into a mold under pressure and solidified under a preset pressure to obtain an aluminum alloy casting.

[0019] Optionally, the preheating temperature of the mold is 200-300° C., the filling speed of the aluminum alloy slurry is ≤5 m / s, and the preset pressure is 40-80 MPa.

[0020] The beneficial effects of the present invention are as follows: adding fine powder to the aluminum alloy melt, thanks to the nano-level TiX powder (TiC powder and / or TiN powder) and micron-level Ti powder contained in the fine powder, effectively increases the nucleation points of aluminum grains, reduces the grain size, reduces the tendency of hot cracking of castings, and significantly improves the mechanical properties of aluminum alloy castings. The fine powder avoids the use of relatively expensive rare earth elements, is not poisoned by alloy strengthening elements such as Zr and Sc, is not easy to agglomerate, and has good grain refinement effect and stability. Before casting, the aluminum alloy melt is cooled to a solid-liquid mixed state with a solid phase content of 40% to 50%. On the one hand, the solidification temperature range of the aluminum alloy melt in the casting process is reduced, and the tendency of hot cracking is reduced. On the other hand, the aluminum grain spheroidization is promoted, and the formation of dendritic grains is avoided, so that the aluminum alloy melt is more easily fed during the solidification process, and also has the effect of reducing the tendency of hot cracking. At the same time, the spherical grains ensure that the solid-liquid mixed state melt still has good castability. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] The casting method of the aluminum alloy with high thermal cracking tendency provided by the embodiment of the present invention comprises the following steps:

[0023] Adding refined powder to the aluminum alloy melt and dispersing it evenly to obtain a mixed melt; the refined powder is micron-sized Ti powder inlaid with nano-sized TiX powder, and the X is selected from at least one of C and N;

[0024] Cooling the mixed melt to a solid-liquid mixed state to obtain an aluminum alloy slurry, wherein the solid content of the aluminum alloy slurry is 40% to 50%;

[0025] The aluminum alloy slurry is die-casted to obtain an aluminum alloy casting.

[0026] In this embodiment, the aluminum alloy melt is added with a refining powder. Thanks to the nano-TiX powder (TiC powder and / or TiN powder) and micron-Ti powder contained in the refining powder, the nucleation points of aluminum grains are effectively increased, the grain size is reduced, the tendency of hot cracking of castings is reduced, and the mechanical properties of aluminum alloy castings are significantly improved. The refining powder avoids the use of relatively expensive rare earth elements, is not poisoned by alloy strengthening elements such as Zr and Sc, is not easy to agglomerate, and has good grain refining effect and stability. Before casting, the aluminum alloy melt is cooled to a solid-liquid mixed state with a solid phase content of 40% to 50%. On the one hand, the solidification temperature range of the aluminum alloy melt in the casting process is reduced, and the tendency of hot cracking is reduced. On the other hand, the aluminum grain spheroidization is promoted, and the formation of dendritic grains is avoided, so that the aluminum alloy melt is easier to be fed during the solidification process, and the tendency of hot cracking is also reduced. At the same time, the spherical grains ensure that the solid-liquid mixed state melt still has good castability.

[0027] In some embodiments, the nano-sized TiX powder is embedded on the surface or inside of the micro-sized Ti powder.

[0028] The average particle size of the nano-scale TiX powder is 40-60 nm, and the average particle size of the micron-scale Ti powder is 40-60 μm.

[0029] In a specific embodiment, the average particle size of the nano-scale TiX powder may be 40 nm, 43 nm, 45 nm, 47 nm, 49 nm, 51 nm, 53 nm, 55 nm, 57 nm or 60 nm. The average particle size of the micron-scale Ti powder may be 40 μm, 43 μm, 45 μm, 47 μm, 49 μm, 51 μm, 53 μm, 55 μm, 57 μm or 60 μm.

[0030] By controlling the particle size of nano-scale TiX powder and micron-scale Ti powder in the refined powder, it is convenient to form multiple nucleation points in the aluminum grains, reduce the grain size, reduce the tendency of hot cracking of the casting, and significantly improve the mechanical properties of the aluminum alloy castings.

[0031] In some embodiments, the mass ratio of the nano-sized TiX powder to the micron-sized Ti powder is 1:(5-20), which facilitates embedding the nano-sized TiX powder on the surface or inside of the micron-sized Ti powder and achieving an ideal TiX powder dispersion effect.

[0032] Preferably, the mass ratio of the nano-sized TiX powder to the micron-sized Ti powder is 1:10.

[0033] In a specific embodiment, the mass ratio of nano-sized TiX powder to micron-sized Ti powder may be 1:5, 1:8, 1:11, 1:13, 1:15, 1:17 or 1:20.

[0034] In a preferred embodiment, the mass ratio of nano-sized TiX powder to micron-sized Ti powder is 1:10.

[0035] In some embodiments, the preparation method of the refined powder includes the following steps: mixing the nano-scale TiX powder and the micron-scale Ti powder to obtain a mixed powder, placing the first mixed powder in a ball mill, weighing ball milling beads to cover the surface of the mixed powder, and then the ball mill is alternately milled in forward and reverse directions, the ball milling speed is 300 to 500 rpm, and the ball milling time is 2 to 4 hours to obtain a refined powder. Specifically, before ball milling, argon or nitrogen is slowly introduced at a flow rate of 1L / min to remove the air in the tank. And every 1h of ball milling, stop ball milling for 10min and cool the ball mill to prevent overheating of the ball mill from causing powder explosion.

[0036] In some embodiments, the mass ratio of the ball milling beads to the mixed powder is (18-20):1.

[0037] In some embodiments, the amount of the refined powder added is 0.1% to 0.5% of the mass of the aluminum alloy melt.

[0038] Specifically, the amount of refined powder added is 0.1%, 0.2%, 0.3%, 0.4% or 0.5% of the mass of the aluminum alloy melt.

[0039] In some embodiments, adding refined powder to the aluminum alloy melt comprises the following steps:

[0040] The refined powder is wrapped with aluminum foil, and then pressed into the aluminum alloy melt through a bell jar, the adding temperature is 760-800°C, stirred for 3-5 minutes, and kept warm for 10-20 minutes, so that the refined powder and the aluminum alloy melt fully react.

[0041] In some embodiments, cooling the mixed melt to a solid-liquid mixed state comprises the following steps:

[0042] The mixed melt is cooled down under eccentric rotation to present a solid-liquid mixed state, the rotation rate of the eccentric rotation is 100 to 200 revolutions per minute, and the rotation time of the eccentric rotation is 1 to 3 minutes.

[0043] In some embodiments, die-casting the alloy slurry to obtain an aluminum alloy casting comprises the following steps:

[0044] The aluminum alloy slurry is filled into a mold under pressure and solidified under a preset pressure to obtain an aluminum alloy casting. Specifically, solidification under a preset pressure ensures that the melt is effectively compensated for shrinkage, further reducing the tendency of thermal cracking.

[0045] In some embodiments, the preheating temperature of the mold is 200-300° C., the filling speed of the aluminum alloy slurry is ≤5 m / s, and the preset pressure is 40-80 MPa.

[0046] The present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0047] Example 1

[0048] 2618 high-strength aluminum alloy is used, and its composition ratio is: Cu 1.9-2.7wt.%, Mg 1.3-1.8wt.%, Fe0.9-1.3wt.%, Ni 0.9-1.2wt.%, Si 0.1-0.25wt.%, Ti 0.04-0.1wt.%, the content of a single element of other elements is less than 0.05wt.%, the total content of other elements is less than 0.15wt.%, and the rest is Al.

[0049] Step 1: Adding fine powder to the aluminum alloy melt, the fine powder is micron-sized Ti powder embedded with nano-sized TiC.

[0050] The average particle size of nano-scale TiC is 50nm, the average particle size of micron-scale Ti powder is 50μm, and the mass ratio of nano-scale TiC to micron-scale Ti powder is 1:10. TiC and Ti powder are mixed to obtain a mixed powder, the mixed powder is put into a ball mill, ball milling beads are weighed to cover the surface of the mixed powder, the mass ratio of the ball milling beads to the mass of the mixed powder is 20:1, and then the ball mill is alternately milled in forward and reverse rotations, the ball milling speed is 400 rpm, and the ball milling time is 3 hours to obtain a refined powder. The amount of refined powder added is 0.3% of the mass of the aluminum alloy melt. The refined powder is wrapped with aluminum foil, and the refined powder is pressed into the aluminum alloy melt through a bell jar. The addition temperature is 780°C, stirred for 5 minutes, and kept warm for 15 minutes to obtain a mixed melt.

[0051] Step 2: cooling the mixed melt to a solid-liquid mixed state temperature range under eccentric rotation conditions to obtain an aluminum alloy slurry with a solid content of 40%;

[0052] The eccentric rotation conditions were: a rotation rate of 180 rpm and a rotation time of 2 min.

[0053] Step 3: Fill the aluminum alloy slurry into the mold cavity under pressure and solidify under high pressure.

[0054] Specifically, a die casting machine is used, the mold preheating temperature is 250° C., the filling speed is 5 m / s, and the solidification pressure is 50 MPa.

[0055] Example 2

[0056] 7075 high-strength aluminum alloy is used, and its composition content is: Zn 5.1-6.1wt.%, Mg 2.1-2.9wt.%, Cu1.2-2.0wt.%, Cr 0.18-0.28wt.%, the content of a single element of other elements is less than 0.05wt.%, the total content of other elements is less than 0.15wt.%, and the rest is Al.

[0057] Step 1: Adding fine powder to the aluminum alloy melt, the fine powder is micron-sized Ti powder embedded with nano-sized TiN.

[0058] The average particle size of TiN is 50nm, the average particle size of Ti powder is 40μm, and the mass ratio of TiN to Ti powder is 1:10. The amount of refined powder added is 0.3% of the mass of the aluminum alloy melt. The refined powder is wrapped with aluminum foil, and the refined powder is pressed into the aluminum alloy melt through a bell jar. The adding temperature is 780°C, stirred for 5 minutes, and kept warm for 15 minutes to obtain a mixed melt.

[0059] Step 2: cooling the mixed melt to a solid-liquid mixed state temperature range under eccentric rotation conditions to obtain an aluminum alloy slurry with a solid content of 45%;

[0060] The eccentric rotation conditions were: a rotation rate of 180 rpm and a rotation time of 80 seconds.

[0061] Step 3: Fill the aluminum alloy slurry into the mold cavity under pressure and solidify under high pressure.

[0062] Specifically, a die casting machine is used, the mold preheating temperature is 200° C., the filling speed is 5 m / s, and the solidification pressure is 50 MPa.

[0063] Example 3

[0064] This embodiment is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, except that the addition amount of the refined powder is 0.1% of the mass of the aluminum alloy melt.

[0065] Example 4

[0066] This embodiment is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, except that the addition amount of the refined powder is 0.2% of the mass of the aluminum alloy melt.

[0067] Example 5

[0068] This embodiment is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, except that the addition amount of the refined powder is 0.4% of the mass of the aluminum alloy melt.

[0069] Example 6

[0070] This embodiment is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, except that the addition amount of the refined powder is 0.5% of the mass of the aluminum alloy melt.

[0071] Example 7

[0072] This embodiment is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, and the difference is that the nano-grade TiX powder is TiN powder.

[0073] Example 8

[0074] This embodiment is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operating steps in the above-mentioned embodiment 1, except that: the nano-grade TiX powder includes TiC powder and TiN powder, and the mass ratio of TiC powder to TiN powder is 1:1.

[0075] Example 9

[0076] This embodiment is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, except that the particle size of the nano-scale TiC is 40 nm, and the particle size of the micron-scale Ti powder is 60 μm.

[0077] Example 10

[0078] This embodiment is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, except that the particle size of the nano-scale TiC is 60nm, and the particle size of the micron-scale Ti powder is 40μm.

[0079] Comparative Example 1

[0080] It adopts 2618 high-strength aluminum alloy and is directly cast by a die-casting machine. The melt pouring temperature is 720℃, the mold preheating temperature is 250℃, the filling speed is 5m / s, and the solidification pressure is 50MPa.

[0081] Comparative Example 2

[0082] It adopts 7075 high-strength aluminum alloy and is directly cast by a die-casting machine. The melt pouring temperature is 720℃, the mold preheating temperature is 250℃, the filling speed is 5m / s, and the solidification pressure is 50MPa.

[0083] Comparative Example 3

[0084] This comparative example is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, and the difference is that: the solid content of the aluminum alloy slurry is 30%.

[0085] Comparative Example 4

[0086] This comparative example is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, which includes most of the operating steps in the above-mentioned embodiment 1, except that: the solid content of the aluminum alloy slurry is 60%, the melt fluidity is poor, and the casting cannot be completely formed.

[0087] Comparative Example 5

[0088] This comparative example is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, and the difference is that the refined powder is 50nm TiC.

[0089] Comparative Example 6

[0090] This comparative example is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, and the difference is that the refined powder is 50 μm Ti powder.

[0091] Comparative Example 7

[0092] This comparative example is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, which includes most of the operation steps in the above-mentioned embodiment 1, and the difference is that the particle size of the nano-grade TiC is 30nm, and the particle size of the micron-grade Ti powder is 30μm.

[0093] Comparative Example 8

[0094] This comparative example is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, which includes most of the operation steps in the above-mentioned embodiment 1, and the difference is that the particle size of the nano-scale TiC is 80nm, and the particle size of the micron-scale Ti powder is 80μm.

[0095] Comparative Example 9

[0096] This comparative example is used to illustrate the preparation method of the rheological die-casting aluminum alloy disclosed in the present invention, and includes most of the operation steps in the above-mentioned embodiment 1, except that the addition amount of the refined powder is 0.8% of the mass of the aluminum alloy melt.

[0097] The aluminum alloys prepared in the above examples and comparative examples were subjected to the following performance tests:

[0098] The tensile strength, yield strength and elongation at break of the material were tested using GB / T 228.1-2010 Tensile test of metallic materials Part 1: Room temperature test method.

[0099] The aluminum alloy die casting specimens prepared from the above components were subjected to tensile property testing using an Instron 3382 electronic universal testing machine with a gauge length of 20 mm and a loading rate of 2 mm / min. The measurement data were recorded, and six specimens were tested at each formulation point, wherein the yield strength, tensile strength and elongation were the average values ​​of the six data, the relative standard deviation of the yield strength was the percentage ratio of the standard deviation of the six yield strength data to the average value, and the relative standard deviation of the tensile strength was the percentage ratio of the standard deviation of the six tensile strength data to the average value. The test results are entered in Table 1.

[0100] Table 1

[0101]

[0102]

[0103] It can be seen from Table 1 that compared with the castings in the comparative example, the castings prepared by the process of the present invention have eliminated the casting cracks of the aluminum alloy with high hot cracking tendency, and the strength and plasticity of the castings are improved. This is because in the process of the present invention, a refining powder composed of nano-TiC or TiN powder and micron Ti powder is added to the aluminum alloy melt, which effectively increases the nucleation particles of aluminum grains, reduces the grain size, reduces the tendency of hot cracking, and significantly improves the mechanical properties of the casting; before casting, the aluminum alloy melt is cooled to a solid-liquid mixed state temperature range with a solid phase content of 40% to 50% under eccentric rotation conditions, reduces the solidification temperature range of the aluminum alloy melt in the casting process, reduces the tendency of hot cracking, and promotes the spheroidization of aluminum grains, avoids the formation of dendritic grains, makes it easier for the aluminum alloy melt to be fed during the solidification process, and also plays an effect of reducing the tendency of hot cracking.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A casting method for an aluminum alloy with a high thermal cracking tendency, characterized in that: The following steps are involved: Adding refined powder to the aluminum alloy melt and dispersing it evenly to obtain a mixed melt; the refined powder is micron-sized Ti powder inlaid with nano-sized TiX powder, and the X is selected from at least one of C and N; The mixed melt is cooled to a solid-liquid mixed state to obtain an aluminum alloy slurry, wherein the solid content of the aluminum alloy slurry is 40% to 50%; The aluminum alloy slurry is die-casted to obtain an aluminum alloy casting.

2. The casting method of the aluminum alloy with high thermal cracking tendency according to claim 1, characterized in that: The nano-scale TiX powder is embedded on the surface or inside of the micro-scale Ti powder; The average particle size of the nano-scale TiX powder is 40-60 nm, and the average particle size of the micron-scale Ti powder is 40-60 μm.

3. The method for preparing the rheological die-casting aluminum alloy according to claim 1 or 2, characterized in that: The mass ratio of the nano-sized TiX powder to the micron-sized Ti powder is 1:(5-20).

4. The casting method of the aluminum alloy with high thermal cracking tendency according to claim 1, characterized in that: The amount of the refined powder added is 0.1% to 0.5% of the mass of the aluminum alloy melt.

5. The casting method of the aluminum alloy with high thermal cracking tendency according to claim 1, characterized in that: Adding refined powder to aluminum alloy melt comprises the following steps: The refined powder is wrapped with aluminum foil, and then the refined powder wrapped with aluminum foil is pressed into the aluminum alloy melt through a bell jar, the adding temperature is 760-800° C., stirring is performed for 3-5 minutes, and heat preservation is performed for 10-20 minutes.

6. The casting method of the aluminum alloy with high thermal cracking tendency according to claim 1, characterized in that: The mixed melt is cooled to a solid-liquid mixed state, comprising the following steps: The mixed melt is cooled down under eccentric rotation to present a solid-liquid mixed state, the rotation rate of the eccentric rotation is 100 to 200 revolutions per minute, and the rotation time of the eccentric rotation is 1 to 3 minutes.

7. The casting method of the aluminum alloy with high thermal cracking tendency according to claim 1, characterized in that: The alloy slurry is die-casted to obtain an aluminum alloy casting, comprising the following steps: The aluminum alloy slurry is filled into a mold under pressure and solidified under a preset pressure to obtain an aluminum alloy casting.

8. The casting method of the aluminum alloy with high thermal cracking tendency according to claim 7, characterized in that: The preheating temperature of the mold is 200-300° C., the filling speed of the aluminum alloy slurry is ≤5 m / s, and the preset pressure is 40-80 MPa.

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