CN111926220A - Aluminum alloy material for high-performance thin-wall 3D printing sand casting and preparation method thereof - Google Patents

Abstract

The invention discloses an aluminum alloy material for high-performance thin-wall 3D printing sand casting and a preparation method thereof, and relates to the technical field of aluminum alloy production. The material comprises the following components in percentage by mass: si: 6.5 to 8 percent; mg: 0.25 to 0.45 percent; ti: 0.05 to 0.16 percent; sr:0.01 to 0.04 percent; fe:0.1 to 0.2 percent; zr: 0.16-0.6%; and (C) Sc: 0 to 0.4 percent; other inevitable impurity elements are less than or equal to 0.10 percent; the balance being Al. In addition, the invention also discloses a preparation method of the high-performance aluminum alloy. The alloy has good fluidity by controlling the contents of Si, Mg, Sr, Ti, Zr and Sc, the structure of the cast 3D printing sand casting is fine and uniform, the strength and toughness of the alloy are remarkably improved, and the requirement for the development of the thin-wall 3D printing sand casting market can be well met.

Description

A kind of aluminum alloy material for high-performance thin-wall 3D printing sand casting and its preparation method

technical field

The invention relates to the technical field of aluminum alloy materials, in particular to an aluminum alloy material for high-performance thin-walled 3D printing sand casting and a preparation method thereof.

Background technique

With the rapid development of modern industry, the scale of the foundry market continues to expand, and the requirements for product complexity and manufacturing flexibility are getting higher and higher. Traditional casting has been unable to meet the market's demand for fast delivery and high-complexity products. The 3D printing sand casting formed by the fusion of 3D printing and traditional resin sand casting has become one of the main development directions of casting. 3D printing sand casting can manufacture highly complex products with rapid manufacturing, especially for the development and production of complex parts (such as automobile cylinder blocks, cylinder heads, etc.). Due to the needs of environmental protection and energy saving, product lightweighting has become a trend of development, and the design of complex parts is constantly developing towards thin-walled and lightweight. Aluminum alloy has high specific strength and low density, and has become the main lightweight material.

Cast aluminum alloys have good casting properties, corrosion resistance, and low casting costs, and are widely used in aerospace and automotive fields. Among them, the cast Al-Si alloy has good fluidity and is widely used in forming complex castings. Microalloying is one of the important means to improve the properties of alloys. The research shows that the addition of Mg element to the cast Al-Si alloy can make the alloy precipitate Mg ₂ Si phase after heat treatment, which greatly improves the strength of the alloy; the addition of Sr element can modify the eutectic silicon to make it small and uniform in size; the addition of Zr, Ti , Sc and rare earth elements can refine the alloy grains and improve the strength and toughness of the alloy at the same time.

Chinese patent CN111074111A discloses a high-strength cast aluminum-silicon alloy and its manufacturing method. The composition of the aluminum-silicon alloy includes: silicon 6.50-7.50%, magnesium 0.30-0.45%, iron≤0.15%, titanium 0.10-0.20% by weight %, zirconium 0.05-0.15%, strontium 0.01%-0.02%, boron ≤ 0.20‰, inevitable impurities ≤ 0.10%, and the balance is Al. After heat treatment, the inventive alloy has a tensile strength of 320-340 MPa, a yield strength of 280-300 MPa, and an elongation of 8%-11%. However, the mold preheating temperature of the inventive alloy needs to be 250°C, because the name mold is only applicable to metal casting molds, that is to say, the high-strength casting alloy is cast from metal molds. Chinese patent CN107385289A discloses a Zr and Sr composite microalloyed high-strength, toughness, corrosion-resistant hypoeutectic Al#Si cast aluminum alloy and its preparation method. The cast aluminum alloy is mainly composed of aluminum (Al), silicon (Si), zirconium (Zr) and strontium (Sr), wherein the mass percentage of silicon (Si) is 7.68-8.18%, the mass percentage of zirconium (Zr) is 0.184-0.191%, and the mass percentage of strontium (Sr) is 0.0199-0.023% , the balance is aluminum and a small amount of impurity elements, and the sum of the mass percentages of each component is 100%. The invention points out that the alloy is poured into a metal mold with a preheating temperature of 300±10° C. to be cast into an ingot, which indicates that the forming method of the alloy of the invention is metal mold casting.

A large number of research results are based on aluminum alloys cast by metal molds. Compared with metal molds, 3D printed resin sand molds have significantly different heat dissipation capabilities, permeability, gas generation and mechanical strength. In addition, due to the complex structure of the sand mold, the green sand mold formed by 3D printing has the characteristics of thin wall, multi-cavity and special shape. The current cast aluminum alloy series materials have poor fluidity, which makes it difficult to fill the local area during the pouring process, resulting in casting defects. ; The cooling speed of the sand mold is slow, the structure of the sand cast aluminum alloy is coarse, the dendrites are developed, and the resin content of the 3D printed sand mold is high, which is easy to form pore defects, resulting in low mechanical properties. As a developing new rapid casting technology, there is no aluminum alloy material specially developed for it at present. In view of this situation, it is urgent to optimize the composition of aluminum alloy by design, and optimize the casting process by design, so as to develop an aluminum alloy material suitable for 3D printing sand casting.

SUMMARY OF THE INVENTION

In order to overcome the above deficiencies in the prior art, the purpose of the present invention is to provide an aluminum alloy material for high-performance thin-walled 3D printing sand casting and a preparation method thereof.

In view of this, the present invention aims to provide an aluminum alloy material for high-performance thin-walled 3D printing sand casting and a preparation method thereof.

The object of the present invention is achieved by at least one of the following technical solutions.

The aluminum alloy material for high-performance thin-wall 3D printing sand casting provided by the present invention, in terms of mass percentage, includes:

Other unavoidable impurity elements≤0.10%;

The remainder is Al.

Further, the aluminum alloy material for the high-performance thin-wall 3D printing sand casting, in terms of mass percentage, includes:

Other unavoidable impurity elements≤0.10%;

The remainder is Al.

The aluminum alloy material for high-performance thin-wall 3D printing sand casting provided by the present invention is suitable for thin-wall (2mm-20mm) 3D printing sand casting products.

A method for preparing the high-performance thin-walled 3D printing aluminum alloy material for sand casting provided by the present invention includes the following steps:

(1) Ingredients, prepare A356 aluminum ingot, Al-10Zr master alloy, Al-2Sc master alloy, Al-10Sr master alloy, Al-5Ti-B master alloy; add A356 aluminum ingot to the crucible, and put the A356 aluminum ingot into In the resistance furnace, program the temperature, and after the charge is completely melted, add Al-10Zr master alloy and Al-2Sc master alloy, stir evenly with a stirring rod to ensure uniform composition, and obtain molten aluminum;

(2) maintaining the temperature of the molten aluminum described in step (1) at 710-730° C., adding Al-5Ti-B master alloy, stirring until it is completely melted, and then standing to obtain a mixed solution;

(3) maintaining the temperature of the mixture described in step (2) at 710-730 ° C, adding Al-10Sr master alloy, stirring until it is completely melted, standing, and slag removal to obtain a mixture;

(4) Pour high-purity argon gas into the mixture described in step (3) to carry out degassing treatment, let stand, remove slag, stabilize the temperature of the mixture at 710-740 ° C, and pour it into a 3D printed sand mold, Then, the casting is heated up in a digital display resistance furnace to perform T6 heat treatment, and then placed at room temperature for air cooling to obtain the aluminum alloy material for high-performance thin-walled 3D printing sand casting.

Further, the temperature program in step (1) is to increase the temperature from room temperature to 730-750°C in an order of increasing 100°C each time.

Further, the stirring time of step (1) is 3-5min.

Further, the standing time described in step (2) is 5-15min.

Further, the standing time described in step (3) is 5-15min.

Further, in step (4), the time for degassing by passing argon into the mixture is 5-15min.

Preferably, in step (4), the time for degassing treatment by passing argon into the mixture is 5 min.

Further, the standing time described in step (4) is 5-15min.

Further, the temperature of the 3D printed sand mold in step (4) is 25-100°C.

Further, the T6 heat treatment in step (4) includes: firstly performing solid solution, the solution temperature is 480-550°C, the solution time is 3-8h, the quenching medium is water, and the temperature of the quenching medium is 4-100°C, After quenching, artificial aging is carried out, the aging temperature is 170-220 ° C, and the aging time is 8-12 hours.

The alloy material of the invention contains Si: 6.5-8%, has good casting fluidity, is suitable for 3D printing thin-walled, special-shaped sand mold cavities, and solves the problem of difficult filling.

The alloy material of the invention contains Mg: 0.25-0.45%, and the alloy undergoes T6 heat treatment to precipitate Mg ₂ Si phase, which greatly improves the strength; the alloy material contains Sr: 0.01-0.04%, so that the eutectic silicon in the alloy structure is fine and uniform .

By controlling the content of Ti, Zr and Sc, the alloy material of the present invention makes the alloy adapt to the thermal conductivity of the 3D printed sand mold, the alloy grains are fine and uniform, and the strength and toughness of the alloy are improved at the same time.

The alloy material of the invention has fine and uniform structure, few pore defects and high density, and solves the problem that the 3D printing sand casting aluminum alloy is prone to pore defects.

After the alloy material of the present invention undergoes T6 heat treatment, nano-precipitated phases containing Zr and Sc are precipitated, which can greatly improve the yield strength and tensile strength.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The invention provides a method for preparing an aluminum alloy material for high-performance thin-walled 3D printing sand casting. The prepared 3D printing sand casting thin-walled aluminum alloy has fine and uniform structure, small petal shape, few pore defects, high density, and heat treatment. It has higher yield strength, tensile strength and elongation after fracture, and higher hardness. Using it for 3D printing sand casting, complex thin-walled parts will have higher service safety and reduce maintenance costs.

Description of drawings

Fig. 1 is the as-cast metallographic diagram of the aluminum alloy in Example 1 of the present invention.

FIG. 2 is an as-cast SEM image of the aluminum alloy in Example 1 of the present invention.

3 is an SEM image of the aluminum alloy in the T6 state of Example 1 of the present invention.

FIG. 4 is the as-cast metallographic diagram of the aluminum alloy in Example 2 of the present invention.

FIG. 5 is an as-cast SEM image of the aluminum alloy in Example 2 of the present invention.

FIG. 6 is an SEM image of the aluminum alloy in the T6 state of Example 2 of the present invention.

7 is a metallographic diagram of the as-cast aluminum alloy of Example 3 of the present invention.

FIG. 8 is an as-cast SEM image of the aluminum alloy in Example 3 of the present invention.

FIG. 9 is an SEM image of the aluminum alloy in the T6 state of Example 3 of the present invention.

FIG. 10 is the as-cast metallographic diagram of the aluminum alloy in Example 4 of the present invention.

11 is an as-cast SEM image of the aluminum alloy of Example 4 of the present invention.

12 is an SEM image of the aluminum alloy in the T6 state of Example 4 of the present invention.

13 is a metallographic diagram of the as-cast aluminum alloy of Example 5 of the present invention.

14 is an as-cast SEM image of the aluminum alloy of Example 5 of the present invention.

15 is an SEM image of the aluminum alloy in the T6 state of Example 5 of the present invention.

16 is a metallographic diagram of the as-cast aluminum alloy of Example 6 of the present invention.

17 is an as-cast SEM image of the aluminum alloy of Example 6 of the present invention.

18 is an SEM image of the aluminum alloy in the T6 state of Example 6 of the present invention.

Detailed ways

The specific implementation of the present invention will be further described below with reference to examples, but the implementation and protection of the present invention are not limited thereto. It should be pointed out that, if there are any processes that are not described in detail below, those skilled in the art can realize or understand them with reference to the prior art. If the reagents or instruments used do not indicate the manufacturer, they are regarded as conventional products that can be purchased in the market.

The aluminum alloy material for thin-wall 3D printing sand casting provided in this embodiment has the following main components and mass percentages: Si: 6.5-8%, Mg: 0.25-0.45%; Ti: 0.1-0.16%; Sr: 0.01- 0.04%; Fe: 0.1-0.2%; Zr: 0.16-0.6%; Sc: 0-0.4%; other unavoidable impurity elements≤0.10%; the balance is Al.

The present invention also provides a method for preparing the above-mentioned thin-walled 3D printing aluminum alloy material for sand casting, comprising the following steps:

Step 1: batching, prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy.

Step 2: Add A356 aluminum ingot into the crucible, put it into the resistance furnace, the resistance furnace is heated up to 730-750 ℃ in the order of increasing 100 ℃ each time, and after the charge is completely melted, add Al-10Zr master alloy and Al-2Sc For the master alloy, stir with a stirring rod for 3-5min to ensure uniform composition;

Step 3: When the temperature of the molten aluminum is stable at 710-730°C, add Al-5Ti-B master alloy, stir until it is completely melted, and let it stand for 5-15min;

Step 4: When the temperature rises to 710-730°C, add Al-10Sr master alloy, stir until it is completely melted, let stand for 5-15min, and remove the slag;

Step 5: Pour high-purity argon gas for degassing, the ventilation time is 5-15min, stand for 5-15min, and the slag is removed.

Step 6: The temperature of the aluminum liquid is stabilized to 710-740°C, and poured into the 3D printed sand mold, and the sand mold temperature is 25-100°C.

Step 7: Perform T6 heat treatment on the casting in a digital display resistance furnace. The specific process is: solution temperature 470-550°C, solution time 3-8h, quenching medium is water, temperature 4-100°C, immediately after quenching. Artificial aging, aging temperature 170-220 ℃, aging time 8-12h. After taking it out, put it in the air to cool at room temperature;

The aluminum alloy material of the present invention uses a 3D printing sand mold to cast a thin-walled casting with very high yield strength, tensile strength and good elongation after fracture.

The 3D printing sand casting aluminum alloy in the embodiment of the present invention can greatly improve the casting performance after T6 heat treatment.

The aluminum alloy material in the embodiment of the present invention can have a hardness of 108HB after T6 heat treatment, and a tensile strength greater than 280MPa.

The present invention will be described in further detail below in conjunction with the embodiments.

Example 1

An aluminum alloy material for high-performance thin-wall 3D printing sand casting, the main components and mass percentages are as follows: Si: 6.5%; Mg: 0.35%; Ti: 0.136%; Sr: 0.031%; Fe: 0.138%; Zr : 0.16%; Sc: 0.15%; other unavoidable impurity elements≤0.10%; the balance is Al.

Step 1: batching, prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy.

Step 2: Add A356 aluminum ingot into the crucible and put it into the resistance furnace. The resistance furnace is heated to 750 °C in the order of increasing 100 °C each time. After the charge is completely melted, add Al-10Zr intermediate alloy and Al-2Sc intermediate Alloy, stir with a stirring rod for 3 minutes to ensure uniform composition;

Step 3: When the temperature of the molten aluminum is stabilized at 710°C, add the Al-5Ti-B master alloy, stir until it is completely melted, and let it stand for 5 minutes;

Step 4: When the temperature rises back to 720°C, add Al-10Sr master alloy, stir until it is completely melted, let it stand for 5 minutes, and remove the slag;

Introduce high-purity argon to degas, ventilate for 5 minutes, let stand for 7 minutes, and remove slag.

The temperature of the molten aluminum returned to 725°C, poured into the 3D printed sand mold, and the sand mold temperature was 50°C;

The castings were subjected to T6 heat treatment. The specific process was: solution temperature 540°C, solution time 3h, quenching medium was water, temperature 60°C, artificial aging immediately after quenching, aging temperature 170°C, aging time 12h. Take it out and let it cool at room temperature.

The wall thickness of the cast castings was 10 mm.

Figure 1 is the as-cast metallographic diagram of the aluminum alloy of Example 1. It can be seen from Figure 1 that the composition and formula of the material are suitable for the thermal conductivity of the 3D printing sand mold, and the structure is fine and uniform, and there are no coarse dendrites. FIG. 2 is an as-cast SEM image of the aluminum alloy of Example 1. It can be seen from FIG. 2 that the size of the eutectic silicon of the material is small and uniform. FIG. 3 is an SEM image of the aluminum alloy in the T6 state of Example 1. It can be seen from FIG. 3 that the eutectic silicon of the material is small and round.

Example 2

An aluminum alloy material for high-performance thin-wall 3D printing sand casting, the main components and mass percentages are as follows: Si: 7.12%, Mg: 0.38%; Ti: 0.05%; Sr: 0.038%; Fe: 0.2%; Zr : 0.25%; Sc: 0.3%; other unavoidable impurity elements≤0.10%; the balance is Al.

Step 1: batching, prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy;

Step 2: Add A356 aluminum ingot into the crucible, put it into the resistance furnace, and the resistance furnace is heated to 740 ℃ in the order of increasing 100 ℃ each time. After the charge is completely melted, add Al-10Zr master alloy and Al-2Sc master alloy , stir with a stirring rod for 3 minutes to ensure that the ingredients are uniform;

Step 3: When the temperature of the molten aluminum is stabilized at 715°C, add the Al-5Ti-B master alloy, stir until it is completely melted, and then let it stand for 10 minutes;

Step 4: When the temperature rises back to 730°C, add Al-10Sr master alloy, stir until it is completely melted, stand for 15 minutes, and remove the slag;

Introduce high-purity argon to degas, ventilate for 10 minutes, let stand for 7 minutes, and remove slag.

The temperature of the molten aluminum returned to 730°C, poured into the 3D printed sand mold, and the sand mold temperature was 80°C;

Perform T6 heat treatment on the castings. The specific process is: solution temperature 520°C, solution time 4.5h, quenching medium is water, temperature 70°C, artificial aging immediately after quenching, aging temperature 190°C, aging time 10h. Take it out and let it cool at room temperature.

The wall thickness of the cast castings was 20mm.

Figure 4 is the as-cast metallographic diagram of the aluminum alloy of Example 2. It can be seen from Figure 4 that the composition and formula of the material are suitable for the thermal conductivity of the 3D printing sand mold, and the structure is fine and uniform, and there are no coarse dendrites. FIG. 5 is an as-cast SEM image of the aluminum alloy of Example 2. It can be seen from FIG. 5 that the size of the eutectic silicon of the material is small and uniform. FIG. 6 is the SEM image of the aluminum alloy in the T6 state of Example 2. It can be seen from FIG. 6 that the eutectic silicon is fine and round after the material is heat treated by T6.

Example 3

An aluminum alloy material for high-performance thin-wall 3D printing sand casting, the main components and mass percentages are as follows: Si: 8%; Mg: 0.45%; Ti: 0.145%; Sr: 0.026%; Fe: 0.2%; Zr : 0.30%; Sc: 0.2%; other unavoidable impurity elements≤0.10%; the balance is Al.

Step 1: batching, prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy;

Step 2: Add A356 aluminum ingot into the crucible and put it into the resistance furnace. The resistance furnace is heated up to 745 °C in the order of increasing 100 °C each time. After the charge is completely melted, add the Al-10Zr intermediate alloy and the Al-2Sc intermediate Alloy, stir with a stirring rod for 4 min;

Step 3: When the temperature of the molten aluminum is stable at 720°C, add the Al-5Ti-B master alloy, stir until it is completely melted, and let it stand for 15 minutes;

Step 4: When the temperature rises back to 730°C, add Al-10Sr master alloy, stir until it is completely melted, stand for 15 minutes, and remove the slag;

Introduce high-purity argon to degas, ventilate for 15 minutes, let stand for 10 minutes, and remove slag.

The temperature of the molten aluminum returned to 730°C, poured into the 3D printed sand mold, and the temperature of the sand mold was 60°C;

Perform T6 heat treatment on the castings, the specific process is: solution temperature 510 ℃, solution time 5h, quenching medium is water, temperature 55 ℃, artificial aging immediately after quenching, aging temperature 220 ℃, aging time 8h. Take it out and let it cool at room temperature.

The cast castings had a wall thickness of 4 mm.

FIG. 7 is the as-cast metallographic diagram of the aluminum alloy of Example 3. It can be seen from FIG. 7 that the composition and formula of the material are suitable for the thermal conductivity of the 3D printing sand mold, and the structure is fine and uniform, and there are no coarse dendrites. FIG. 8 is an as-cast SEM image of the aluminum alloy of Example 3. It can be seen from FIG. 8 that the size of the eutectic silicon of the material is small and uniform. FIG. 9 is an SEM image of the aluminum alloy in the T6 state of Example 3. It can be seen from FIG. 9 that the eutectic silicon is fine and round after the material is heat treated by T6.

Example 4

An aluminum alloy material for high-performance thin-wall 3D printing sand casting, the main components and mass percentages are as follows: Si: 7.53%, Mg: 0.40%; Ti: 0.16%; Sr: 0.034%; Fe: 0.156%; Zr : 0.16%; Sc: 0.4%; other unavoidable impurity elements≤0.10%; the balance is Al.

Step 1: Prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy;

Step 2: Add A356 aluminum ingot into the crucible, put it into the resistance furnace, and the resistance furnace is heated to 740 ℃ in the order of increasing 100 ℃ each time. After the charge is completely melted, add Al-10Zr master alloy and Al-2Sc master alloy , stir with a stirring rod for 5min;

Step 3: When the temperature of the molten aluminum is stable at 720°C, add Al-5Ti-B master alloy, stir until it is completely melted, and let it stand for 8 minutes;

Step 4: When the temperature rises to 710°C, add Al-10Sr master alloy, stir until it is completely melted, let stand for 5 minutes, and remove the slag;

Introduce high-purity argon to degas, ventilate for 5 minutes, let stand for 5 minutes, and remove slag.

The temperature of the molten aluminum returned to 730°C, poured into the 3D printed sand mold, and the sand mold temperature was 40°C;

The castings were subjected to T6 heat treatment. The specific process was: solution temperature 540°C, solution time 4.2h, quenching medium was water, temperature 70°C, artificial aging immediately after quenching, aging temperature 180°C, aging time 8.5h. Take it out and let it cool at room temperature.

The cast casting wall thickness was 2mm.

Fig. 10 is the as-cast metallographic diagram of the aluminum alloy of Example 4. It can be seen from Fig. 10 that the composition of the material is suitable for the thermal conductivity of the 3D printing sand mold, and the structure is fine and uniform, and there are no coarse dendrites. FIG. 11 is an as-cast SEM image of the aluminum alloy of Example 4. It can be seen from FIG. 11 that the size of the eutectic silicon of the material is fine and uniform. 12 is the SEM image of the aluminum alloy in the T6 state of Example 4. It can be seen from FIG. 12 that the eutectic silicon is fine and round after the material is heat treated by T6.

Example 5

An aluminum alloy material for high-performance thin-wall 3D printing sand casting, the main components and mass percentages are as follows: Si: 6.5%; Mg: 0.32%; Ti: 0.10%; Sr: 0.01%; Fe: 0.16%; Zr : 0.6%; Sc: 0%; other unavoidable impurity elements≤0.10%; the balance is Al.

Step 1: Prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy;

Step 2: Add A356 aluminum ingot into the crucible, put it into the resistance furnace, and the resistance furnace is heated to 740 ℃ in the order of increasing 100 ℃ each time. After the charge is completely melted, add Al-10Zr master alloy and Al-2Sc master alloy , stir with a stirring rod for 5min;

Step 3: When the temperature of the molten aluminum is stable at 720°C, add Al-5Ti-B master alloy, stir until it is completely melted, and let it stand for 8 minutes;

Step 4: When the temperature rises back to 730°C, add Al-10Sr master alloy, stir until it is completely melted, let it stand for 5 minutes, and remove the slag;

Introduce high-purity argon to degas, ventilate for 5 minutes, let stand for 15 minutes, and remove slag.

The temperature of the molten aluminum returned to 730°C, poured into the 3D printed sand mold, and the sand mold temperature was 100°C;

The castings were subjected to T6 heat treatment. The specific process was: solution temperature 550°C, solution time 3h, quenching medium was water, temperature 70°C, artificial aging immediately after quenching, aging temperature 220°C, aging time 8h. Take it out and let it cool at room temperature.

The cast casting wall thickness was 12mm.

Figure 13 is the as-cast metallographic diagram of the aluminum alloy of Example 5. It can be seen from Figure 13 that the composition of the material is suitable for the thermal conductivity of the 3D printing sand mold, and its structure is fine and uniform, and there are no coarse dendrites. FIG. 14 is an as-cast SEM image of the aluminum alloy of Example 5. It can be seen from FIG. 14 that the size of the eutectic silicon of the material is fine and uniform. FIG. 15 is the SEM image of the aluminum alloy in the T6 state of Example 5. It can be seen from FIG. 15 that the eutectic silicon is fine and round after the material is heat treated by T6.

Example 6

An aluminum alloy material for high-performance thin-wall 3D printing sand casting, the main components and mass percentages are as follows: Si: 6.9%, Mg: 0.4%; Ti: 0.145%; Sr: 0.04%; Fe: 0.1%; Zr : 0.2%; Sc: 0.02%; other unavoidable impurity elements≤0.10%; the balance is Al.

Step 1: Prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy;

Step 2: Add A356 aluminum ingot into the crucible, put it into the resistance furnace, and the resistance furnace is heated to 740 ℃ in the order of increasing 100 ℃ each time. After the charge is completely melted, add Al-10Zr master alloy and Al-2Sc master alloy , stir with a stirring rod for 5min;

Step 3: When the temperature of the molten aluminum is stable at 720°C, add Al-5Ti-B master alloy, stir until it is completely melted, and let it stand for 8 minutes;

Step 4: When the temperature rises to 730°C, add Al-10Sr master alloy, stir until it is completely melted, let it stand for 5 minutes, and remove the slag;

Introduce high-purity argon to degas, ventilate for 5 minutes, let stand for 7 minutes, and remove slag.

The temperature of the molten aluminum returned to 730°C, poured into the 3D printed sand mold, and the sand mold temperature was 25°C;

The castings were subjected to T6 heat treatment. The specific process was: solution temperature 480°C, solution time 8h, quenching medium was water, temperature 4°C, artificial aging immediately after quenching, aging temperature 180°C, aging time 11h. Take it out and let it cool at room temperature.

The cast castings had a wall thickness of 6 mm.

Fig. 16 is the as-cast metallographic diagram of the aluminum alloy of Example 6. It can be seen from Fig. 16 that the composition of the material is suitable for the thermal conductivity of the 3D printing sand mold, and its structure is fine and uniform, and there are no coarse dendrites. FIG. 17 is an as-cast SEM image of the aluminum alloy of Example 6. It can be seen from FIG. 17 that the size of the eutectic silicon of the material is fine and uniform. FIG. 18 is an SEM image of the aluminum alloy in the T6 state of Example 6. It can be seen from FIG. 18 that the eutectic silicon is fine and round after the material is heat-treated by T6.

Example 7

An aluminum alloy material for high-performance thin-wall 3D printing sand casting, the main components and mass percentages are as follows: Si: 8%, Mg: 0.25%; Ti: 0.15%; Sr: 0.026%; Fe: 0.14%; Zr : 0.20%; Sc: 0.02%; other unavoidable impurity elements≤0.10%; the balance is Al.

Step 1: Prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy;

Step 2: Add A356 aluminum ingot into the crucible, put it into the resistance furnace, and the resistance furnace is heated to 740 ℃ in the order of increasing 100 ℃ each time. After the charge is completely melted, add Al-10Zr master alloy and Al-2Sc master alloy , stir with a stirring rod for 5min;

Step 3: When the temperature of the molten aluminum is stable at 720°C, add Al-5Ti-B master alloy, stir until it is completely melted, and let it stand for 8 minutes;

Step 4: When the temperature rises back to 730°C, add Al-10Sr master alloy, stir until it is completely melted, let it stand for 5 minutes, and remove the slag;

Introduce high-purity argon to degas, ventilate for 7 minutes, let stand for 7 minutes, and remove slag.

The temperature of the molten aluminum returned to 730°C, poured into the 3D printed sand mold, and the sand mold temperature was 50°C;

The castings were subjected to T6 heat treatment. The specific process was: solution temperature 540°C, solution time 4.2h, quenching medium was water, temperature 70°C, artificial aging immediately after quenching, aging temperature 180°C, aging time 8.5h. Take it out and let it cool at room temperature.

The cast castings had a wall thickness of 8 mm.

Comparative Example 1: The composition and mass percentage are: Si: 5.91%, Mg: 0.23%; Ti: 0.146%; Sr: 0.011%; Fe: 0.136%; Zr: 0.1%; Sc: 0.05%; the balance is Al.

Step 1: Prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy;

Step 2: Add A356 aluminum ingot into the crucible, put it into the resistance furnace, and the resistance furnace is heated to 740 ℃ in the order of increasing 100 ℃ each time. After the charge is completely melted, add Al-10Zr master alloy and Al-2Sc master alloy , stir with a stirring rod for 5min;

Step 3: When the temperature of the molten aluminum is stable at 720°C, add Al-5Ti-B master alloy, stir until it is completely melted, and let it stand for 8 minutes;

Step 4: When the temperature rises to 730°C, add Al-10Sr master alloy, stir until it is completely melted, let it stand for 5 minutes, and remove the slag;

Introduce high-purity argon to degas, ventilate for 5 minutes, let stand for 7 minutes, and remove slag.

The temperature of the molten aluminum returned to 730°C, poured into the 3D printed sand mold, and the sand mold temperature was 25°C;

The castings were subjected to T6 heat treatment. The specific process was: solution temperature 480°C, solution time 8h, quenching medium water, temperature 4°C, artificial aging immediately after quenching, aging temperature 160°C, aging time 11h. Take it out and let it cool at room temperature.

The wall thickness of the casting cast in Comparative Example 1 was 15 mm.

Comparative Example 2: The composition and mass percentage are: Si: 8.31%, Mg: 0.43%; Ti: 0.04%; Sr: 0.05%; Fe: 0.16%; Zr: 0.15%; the balance is Al.

Step 1: Prepare A356 aluminum ingot, Al-10Zr master alloy, Al-10Sr master alloy, Al-2Sc master alloy and Al-5Ti-B master alloy;

Step 2: Add A356 aluminum ingot into the crucible, put it into the resistance furnace, and the resistance furnace is heated to 740 ℃ in the order of increasing 100 ℃ each time. After the charge is completely melted, add Al-10Zr master alloy and Al-2Sc master alloy , stir with a stirring rod for 5min;

Step 3: When the temperature of the molten aluminum is stable at 720°C, add Al-5Ti-B master alloy, stir until it is completely melted, and let it stand for 8 minutes;

Step 4: When the temperature rises to 730°C, add Al-10Sr master alloy, stir until it is completely melted, let it stand for 5 minutes, and remove the slag;

Introduce high-purity argon to degas, ventilate for 5 minutes, let stand for 7 minutes, and remove slag.

The temperature of the molten aluminum returned to 730°C, poured into the 3D printed sand mold, and the sand mold temperature was 100°C;

The castings were subjected to T6 heat treatment. The specific process was: solution temperature 480°C, solution time 8h, quenching medium was water, temperature 4°C, artificial aging immediately after quenching, aging temperature 250°C, aging time 11h. Take it out and let it cool at room temperature.

The wall thickness of the casting cast in Comparative Example 2 was 15 mm. It can be seen from the data in Table 1 that the yield strength of the 3D printed sand casting aluminum alloys prepared in Examples 1 to 7 is greater than 250MPa, the tensile strength is greater than 290MPa, the hardness is greater than 100HB, and the elongation is greater than 2%. The tensile strength and yield strength are much greater than those of Comparative Examples 1 and 2, and the elongation and hardness data are both greater than those of Comparative Examples 1 and 2. And the aluminum alloy of the present invention is especially suitable for thin-wall 3D printing sand casting, which can bring higher service safety and reduce maintenance costs.

The room temperature tensile mechanical property test (GB/T 228.1-2010) and the Brinell hardness test were performed on each embodiment and the comparative example, and the test results are shown in Table 1 below.

Table 1

It can be seen from the data in Table 1 that the yield strength of the 3D printed sand casting aluminum alloys prepared in Examples 1 to 7 is greater than 250MPa, the tensile strength is greater than 290MPa, the hardness is greater than 100HB, and the elongation is greater than 2%. The tensile strength and yield strength are much greater than those of Comparative Examples 1 and 2, and the elongation and hardness data are both greater than those of Comparative Examples 1 and 2. And the aluminum alloy of the present invention is especially suitable for thin-wall 3D printing sand casting, which can bring higher service safety and reduce maintenance costs.

The above examples are only preferred embodiments of the present invention, and are only used to explain the present invention, but not to limit the present invention. Changes, substitutions, modifications, etc. made by those skilled in the art without departing from the spirit of the present invention shall belong to the present invention. the scope of protection of the invention.

Claims (10)

1. The utility model provides an aluminum alloy material that high performance thin wall 3D printed sand casting used which characterized in that, according to the mass percent, includes:

Si 6.5-8%；

Mg 0.25-0.45%；

Ti 0.05-0.16%；

Sr 0.01-0.04%；

Fe 0.1-0.2%；

Zr 0.16-0.6%；

Sc 0-0.4%；

the balance being Al.

2. The aluminum alloy material for high-performance thin-wall 3D printing sand casting according to claim 1, which comprises the following components in percentage by mass:

Si 6.5-8%；

Mg 0.25-0.45%；

Ti 0.1-0.16%；

Sr 0.01-0.04%；

Fe 0.1-0.2%；

Zr 0.16-0.6%；

Sc 0-0.4%；

the balance being Al.

3. A method for preparing the aluminum alloy material for high-performance thin-wall 3D printing sand casting according to any one of claims 1 to 2, which is characterized by comprising the following steps:

(1) putting an A356 aluminum ingot into a resistance furnace, raising the temperature by program, adding Al-10Zr intermediate alloy and Al-2Sc intermediate alloy after furnace burden is completely melted, and stirring uniformly to obtain aluminum liquid;

(2) keeping the temperature of the aluminum liquid in the step (1) at 710-730 ℃, adding Al-5Ti-B intermediate alloy, stirring until the intermediate alloy is completely melted, and standing to obtain a mixed liquid;

(3) keeping the temperature of the mixture in the step (2) at 710-730 ℃, adding Al-10Sr intermediate alloy, stirring until the intermediate alloy is completely melted, standing, and slagging off to obtain a mixture;

(4) and (4) introducing argon into the mixture obtained in the step (3) for degassing treatment, standing, slagging off, stabilizing the temperature of the mixture at 740 ℃ of 710-.

4. The preparation method of the aluminum alloy material for high-performance thin-walled 3D printing sand casting according to claim 3, wherein the temperature programming in the step (1) is to increase the temperature from room temperature to 730-750 ℃ in the order of 100 ℃ rise each time.

5. The preparation method of the aluminum alloy material for high-performance thin-wall 3D printing sand casting according to claim 3, wherein the stirring time in the step (1) is 3-5 min.

6. The preparation method of the aluminum alloy material for high-performance thin-wall 3D printing sand casting according to claim 3, wherein the standing time in the step (2) is 5-15 min.

7. The preparation method of the aluminum alloy material for high-performance thin-wall 3D printing sand casting according to claim 3, wherein the standing time in the step (3) is 5-15 min.

8. The preparation method of the aluminum alloy material for the high-performance thin-wall 3D printing sand casting according to claim 3, wherein in the step (4), argon is introduced into the mixture for degassing treatment for 5-15 min; the standing time is 5-15 min.

9. The preparation method of the aluminum alloy material for high-performance thin-wall 3D printing sand casting according to claim 3, wherein the temperature of the 3D printing sand mold in the step (4) is 25-100 ℃.

10. The method for preparing the aluminum alloy material for high-performance thin-walled 3D printing sand casting according to claim 3, wherein the T6 heat treatment in the step (4) comprises the following steps: firstly carrying out solid solution at the temperature of 480-550 ℃, the solid solution time of 3-8h, the quenching medium of water and the quenching medium of 4-100 ℃, and then carrying out artificial aging at the aging temperature of 170-220 ℃ and the aging time of 8-12 h.

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