CN111926220A

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

Info

Publication number: CN111926220A
Application number: CN202010706671.5A
Authority: CN
Inventors: 朱德智; 赖晓玉; 陈维平; 詹泉泉; 徐伟业
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2020-07-21
Filing date: 2020-07-21
Publication date: 2020-11-13

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

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

Technical Field

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

Background

With the rapid development of modern industry, the casting market scale continues to expand, the requirements for product complexity and manufacturing flexibility become higher and higher, and the demand of the market for rapid delivery and high-complexity products cannot be met by traditional casting. 3D printing sand mold casting formed by mutually fusing 3D printing and traditional resin sand casting becomes one of the main development directions of casting. The 3D printing sand casting can manufacture highly complex products, is quick to manufacture, and is particularly suitable for research and development and production of complex parts (such as automobile cylinder bodies, cylinder covers and the like). Due to the requirements of environmental protection and energy conservation, the light weight of products becomes a development trend, and the design of complex parts is continuously developed towards the direction of thinning and light weight. Aluminum alloys have high specific strength and low density, and are the main lightweight materials.

The cast aluminum alloy has good casting performance, corrosion resistance and low casting cost, and is widely applied to the fields of aerospace, automobiles and the like. The cast Al-Si alloy has good fluidity and is widely applied to forming complex castings. Microalloying is one of the important means to improve the performance of the alloy. Research shows that Mg is precipitated after the alloy is subjected to heat treatment by adding Mg element into cast aluminum-silicon alloy₂The Si phase greatly improves the strength of the alloy; the Sr element is added to modify eutectic silicon, so that the eutectic silicon is fine and uniform in size; zr, Ti, Sc, rare earth elements and the like are added to refine alloy grains and improve the strength and toughness of the alloy.

The patent CN111074111A discloses a high-strength cast aluminum-silicon alloy and a manufacturing method thereof, wherein the aluminum-silicon alloy comprises the following components in percentage by weight: 6.50 to 7.50 percent of silicon, 0.30 to 0.45 percent of magnesium, less than or equal to 0.15 percent of iron, 0.10 to 0.20 percent of titanium, 0.05 to 0.15 percent of zirconium, 0.01 to 0.02 percent of strontium, less than or equal to 0.20 percent of boron, less than or equal to 0.10 percent of inevitable impurities, and the balance of Al. The tensile strength of the alloy can reach 320-340MPa, the yield strength can reach 280-300MPa and the elongation can reach 8-11 percent after heat treatment. However, the die preheating temperature of the alloy of the invention needs 250 ℃ because the die name is only applicable to metal molds, that is, the high-strength casting alloy is cast by a metal die. The Zr-Sr composite microalloyed high-strength corrosion-resistant hypoeutectic Al # Si cast aluminum alloy and the preparation method thereof are disclosed in Chinese patent CN107385289A, the cast aluminum alloy mainly comprises aluminum (Al), silicon (Si), zirconium (Zr) and strontium (Sr), wherein the mass percent of the silicon (Si) is 7.68-8.18%, the mass percent of the zirconium (Zr) is 0.184-0.191%, the mass percent of the strontium (Sr) is 0.0199-0.023%, the balance is aluminum and a small amount of impurity elements, and the sum of the mass percent of the components is 100%. The invention points out that the alloy is poured into a metal mould with the preheating temperature of 300 +/-10 ℃ to be cast into an ingot, which indicates that the forming mode of the alloy is metal mold casting.

A great deal of research results are obtained based on aluminum alloy cast by a metal mold, and compared with the metal mold, a resin sand mold for 3D printing has significantly different heat dissipation capacity, permeability, gas generation property, mechanical strength and the like. In addition, because the sand mold structure is complex, the sand mold green body formed by 3D printing has the characteristics of thin wall, multiple cavities and special shapes, and the conventional cast aluminum alloy series has poor flowability, so that the local area of the cast aluminum alloy series is difficult to fill in the casting process, and casting defects are formed; the cooling speed of the sand mold is low, the structure of the sand casting aluminum alloy is thick, the dendritic crystal is developed, the resin content of the sand mold for 3D printing is high, the pore defect is easily formed, and the mechanical property is low. As a new type of rapid casting technology in development, there is currently no aluminum alloy material specifically developed for it. In order to solve the problem, the aluminum alloy material suitable for 3D printing sand casting needs to be developed through designing and optimizing aluminum alloy components and designing and optimizing casting technology.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide an aluminum alloy material for high-performance thin-wall 3D printing sand casting and a preparation method thereof.

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

The purpose of the invention is realized by at least one of the following technical solutions.

The invention provides an aluminum alloy material for high-performance thin-wall 3D printing sand casting, which comprises the following components in percentage by mass:

other inevitable impurity elements are less than or equal to 0.10 percent;

the balance being Al.

Further, the aluminum alloy material for sand casting through high-performance thin-wall 3D printing comprises the following components in percentage by mass:

other inevitable impurity elements are less than or equal to 0.10 percent;

the balance being Al.

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

The invention provides a method for preparing an aluminum alloy material for high-performance thin-wall 3D printing sand casting, which comprises the following steps of:

(1) preparing materials, namely preparing an A356 aluminum ingot, an Al-10Zr intermediate alloy, an Al-2Sc intermediate alloy, an Al-10Sr intermediate alloy and an Al-5Ti-B intermediate alloy; adding an A356 aluminum ingot into a crucible, putting the A356 aluminum ingot into a resistance furnace, programming to raise the temperature, adding an Al-10Zr intermediate alloy and an Al-2Sc intermediate alloy after furnace burden is completely melted, and uniformly stirring by using a stirring rod to ensure uniform components 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 high-purity 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 and 740 ℃, pouring the mixture into a 3D printed sand mold, then heating the mixture in a digital display resistance furnace to perform T6 heat treatment on the casting, and air-cooling the casting at room temperature to obtain the aluminum alloy material for casting the high-performance thin-wall 3D printed sand mold.

Further, the temperature programming in step (1) is to increase the temperature from room temperature to 730-750 ℃ in the order of 100 ℃ rise each time.

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

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

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

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

Preferably, in the step (4), argon gas is introduced into the mixture for degassing for 5 min.

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

Further, the temperature of the sand mold for 3D printing in the step (4) is 25-100 ℃.

Further, the T6 heat treatment of step (4) includes: 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.

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

The alloy material of the present invention contains Mg: 0.25-0.45%, and Mg is precipitated from the alloy after T6 heat treatment₂Si phase, the strength is greatly improved; the alloy material contains Sr: 0.01-0.04% to make eutectic silicon in alloy structure fine and uniform.

The alloy material disclosed by the invention has the advantages that the heat conductivity of the alloy suitable for a sand mold for 3D printing is realized by controlling the contents of Ti, Zr and Sc, the alloy grains are fine and uniform, and the strength and toughness of the alloy are improved.

The alloy material provided by the invention has the advantages of fine and uniform structure, less pore defects and high density, and solves the problem that the aluminum alloy cast by 3D printing sand mold is easy to generate pore defects.

After the alloy material is subjected to T6 heat treatment, nanometer precipitated phases containing Zr and Sc are precipitated, and the yield strength and the tensile strength can be greatly improved.

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

according to the preparation method of the aluminum alloy material for the high-performance thin-wall 3D printing sand casting, the prepared 3D printing sand casting thin-wall aluminum alloy has the advantages of fine and uniform tissue, fine petal shape, less pore defects, high density, higher yield strength, tensile strength, elongation after fracture and higher hardness after heat treatment, and when the aluminum alloy material is used for 3D printing sand casting, complex thin-wall parts have higher service safety and can reduce maintenance cost.

Drawings

FIG. 1 is an as-cast gold phase diagram of an aluminum alloy of example 1 of the present invention.

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

FIG. 3 is an SEM image of the T6 state of the aluminum alloy of example 1.

FIG. 4 is an as-cast gold phase diagram of the aluminum alloy of example 2 of the present invention.

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

FIG. 6 is an SEM image of the T6 state of the aluminum alloy of example 2.

FIG. 7 is an as-cast gold phase diagram of the aluminum alloy of example 3 of the present invention.

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

FIG. 9 is an SEM image of the T6 state of the aluminum alloy of example 3.

FIG. 10 is an as-cast gold phase diagram of the aluminum alloy of example 4 of the present invention.

FIG. 11 is an as-cast SEM image of the aluminum alloy of example 4 of the invention.

FIG. 12 is an SEM image of the T6 state of the aluminum alloy of example 4 of the invention.

FIG. 13 is an as-cast gold phase diagram of the aluminum alloy of example 5 of the present invention.

FIG. 14 is an as-cast SEM image of the aluminum alloy of example 5 of the invention.

FIG. 15 is an SEM image of the T6 state of the aluminum alloy of example 5 in accordance with the invention.

FIG. 16 is an as-cast gold phase diagram of the aluminum alloy of example 6 of the present invention.

FIG. 17 is an as-cast SEM image of the aluminum alloy of example 6 of the invention.

FIG. 18 is an SEM image of the T6 state of the aluminum alloy of example 6 of the invention.

Detailed Description

The following examples are presented to further illustrate the practice of the invention, but the practice and protection of the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art. The reagents or apparatus used are not indicated to the manufacturer, and are considered to be conventional products available by commercial purchase.

The aluminum alloy material for the thin-wall 3D printing sand casting provided by the embodiment comprises the following main components in percentage by mass: si: 6.5-8%, Mg: 0.25 to 0.45 percent; ti: 0.1 to 0.16 percent; 0.01 to 0.04 percent of Sr; 0.1 to 0.2 percent of Fe; 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.

The invention also provides a preparation method of the aluminum alloy material for the thin-wall 3D printing sand casting, which comprises the following steps:

step 1: proportioning, preparing A356 aluminum ingot, Al-10Zr intermediate alloy, Al-10Sr intermediate alloy, Al-2Sc intermediate alloy and Al-5Ti-B intermediate alloy.

Step 2: adding an A356 aluminum ingot into a crucible, putting the crucible into a resistance furnace, heating the resistance furnace to 730-750 ℃ according to the sequence of raising the temperature by 100 ℃ each time, adding Al-10Zr intermediate alloy and Al-2Sc intermediate alloy after furnace burden is completely melted, and stirring for 3-5min by using a stirring rod to ensure uniform components;

and step 3: when the temperature of the aluminum liquid is stabilized at 710-730 ℃, adding Al-5Ti-B intermediate alloy, stirring until the intermediate alloy is completely melted, and standing for 5-15 min;

and 4, step 4: when the temperature is raised to 710-730 ℃, adding Al-10Sr intermediate alloy, stirring until the intermediate alloy is completely melted, standing for 5-15min, and slagging off;

and 5: introducing high-purity argon gas for degassing for 5-15min, standing for 5-15min, and removing slag.

Step 6: the temperature of the aluminum liquid is stabilized to 710-740 ℃, and the aluminum liquid is poured into a sand mold for 3D printing, wherein the temperature of the sand mold is 25-100 ℃.

And 7: t6 heat treatment is carried out on the casting in a digital display resistance furnace, and the specific process comprises the following steps: the solid solution temperature is 470-550 ℃, the solid solution time is 3-8h, the quenching medium is water, the temperature is 4-100 ℃, the artificial aging is immediately carried out after the quenching is finished, the aging temperature is 170-220 ℃, and the aging time is 8-12 h. Taking out and then placing at room temperature for air cooling;

the thin-wall casting cast by the 3D printing sand mold of the aluminum alloy material has very high yield strength, tensile strength and good elongation after fracture.

After the 3D printing sand casting aluminum alloy is subjected to T6 heat treatment, the casting performance can be greatly improved.

After the aluminum alloy material provided by the embodiment of the invention is subjected to T6 heat treatment, the hardness can reach 108HB, and the tensile strength is more than 280 MPa.

The present invention will be described in further detail with reference to examples.

Example 1

An aluminum alloy material for high-performance thin-wall 3D printing sand casting comprises the following main components in percentage by mass: si: 6.5 percent; mg: 0.35 percent; ti: 0.136%; sr: 0.031%; fe: 0.138%; zr: 0.16 percent; and (C) Sc: 0.15 percent; other inevitable impurity elements are less than or equal to 0.10 percent; the balance being Al.

Step 2: adding an A356 aluminum ingot into a crucible, putting the crucible into a resistance furnace, heating the resistance furnace to 750 ℃ according to the sequence of raising the temperature by 100 ℃ each time, adding Al-10Zr intermediate alloy and Al-2Sc intermediate alloy after furnace burden is completely melted, and stirring for 3min by using a stirring rod to ensure that the components are uniform;

and step 3: when the temperature of the aluminum liquid is stabilized at 710 ℃, adding Al-5Ti-B intermediate alloy, stirring until the intermediate alloy is completely melted, and standing for 5 min;

and 4, step 4: when the temperature rises to 720 ℃, adding Al-10Sr intermediate alloy, stirring until the intermediate alloy is completely melted, standing for 5min, and slagging off;

introducing high-purity argon gas for degassing, introducing gas for 5min, standing for 7min, and removing slag.

The temperature of the aluminum liquid is raised to 725 ℃, and the aluminum liquid is poured into a sand mold for 3D printing, wherein the temperature of the sand mold is 50 ℃;

t6 heat treatment is carried out on the casting, and the specific process comprises the following steps: the solution temperature is 540 ℃, the solution time is 3 hours, the quenching medium is water, the temperature is 60 ℃, the artificial aging is carried out immediately after the quenching is finished, the aging temperature is 170 ℃, and the aging time is 12 hours. Taking out and then placing at room temperature for air cooling.

The wall thickness of the cast product was 10 mm.

FIG. 1 is an as-cast metallographic image of the aluminum alloy of example 1, and it can be seen from FIG. 1 that the composition formula of the material is adapted to the heat conductivity of a 3D printing sand mold, and the structure is fine and uniform without coarse dendrites. FIG. 2 is an as-cast SEM image of the aluminum alloy of example 1, and it can be seen from FIG. 2 that the eutectic silicon size of the material is fine and uniform. FIG. 3 is a SEM image of the aluminum alloy T6 of example 1 in a state, and it can be seen from FIG. 3 that the eutectic silicon of the material is fine and round.

Example 2

An aluminum alloy material for high-performance thin-wall 3D printing sand casting comprises the following main components in percentage by mass: si: 7.12%, Mg: 0.38 percent; ti: 0.05 percent; sr: 0.038%; fe: 0.2 percent; zr: 0.25 percent; and (C) Sc: 0.3 percent; other inevitable impurity elements are less than or equal to 0.10 percent; the balance being Al.

Step 1: preparing materials, namely preparing an A356 aluminum ingot, an Al-10Zr intermediate alloy, an Al-10Sr intermediate alloy, an Al-2Sc intermediate alloy and an Al-5Ti-B intermediate alloy;

step 2: adding an A356 aluminum ingot into a crucible, putting the crucible into a resistance furnace, heating the resistance furnace to 740 ℃ according to the sequence of raising the temperature by 100 ℃ each time, adding Al-10Zr intermediate alloy and Al-2Sc intermediate alloy after furnace burden is completely melted, and stirring for 3min by using a stirring rod to ensure that the components are uniform;

and step 3: when the temperature of the aluminum liquid is stabilized at 715 ℃, adding Al-5Ti-B intermediate alloy, stirring until the intermediate alloy is completely melted, and standing for 10 min;

and 4, step 4: when the temperature rises to 730 ℃, adding Al-10Sr intermediate alloy, stirring until the intermediate alloy is completely melted, standing for 15min, and slagging off;

introducing high-purity argon gas for degassing, introducing gas for 10min, standing for 7min, and removing slag.

The temperature of the aluminum liquid is raised to 730 ℃, and the aluminum liquid is poured into a sand mold for 3D printing, wherein the temperature of the sand mold is 80 ℃;

t6 heat treatment is carried out on the casting, and the specific process comprises the following steps: the solution temperature is 520 ℃, the solution time is 4.5h, the quenching medium is water, the temperature is 70 ℃, the artificial aging is carried out immediately after the quenching is finished, the aging temperature is 190 ℃, and the aging time is 10 h. Taking out and then placing at room temperature for air cooling.

The wall thickness of the cast product was 20 mm.

FIG. 4 is the as-cast phase diagram of the aluminum alloy of example 2, and it can be seen from FIG. 4 that the composition formula of the material is adapted to the heat conductivity of the 3D printing sand mold, and the structure is fine and uniform without coarse dendrites. FIG. 5 is an as-cast SEM image of the aluminum alloy of example 2, and it can be seen from FIG. 5 that the eutectic silicon size of the material is fine and uniform. FIG. 6 is a SEM image of the aluminum alloy T6 of example 2, and it can be seen from FIG. 6 that the eutectic silicon is fine and round after the material is subjected to T6 heat treatment.

Example 3

An aluminum alloy material for high-performance thin-wall 3D printing sand casting comprises the following main components in percentage by mass: si: 8 percent; mg: 0.45 percent; ti: 0.145 percent; sr: 0.026%; fe: 0.2 percent; zr: 0.30 percent; and (C) Sc: 0.2 percent; other inevitable impurity elements are less than or equal to 0.10 percent; the balance being Al.

step 2: adding an A356 aluminum ingot into a crucible, putting the crucible into a resistance furnace, heating the resistance furnace to 745 ℃ according to the sequence of raising the temperature by 100 ℃ each time, adding Al-10Zr intermediate alloy and Al-2Sc intermediate alloy after furnace burden is completely melted, and stirring for 4min by using a stirring rod;

and step 3: when the temperature of the aluminum liquid is stable at 720 ℃, adding Al-5Ti-B intermediate alloy, stirring until the intermediate alloy is completely melted, and standing for 15 min;

introducing high-purity argon gas for degassing, introducing the gas for 15min, standing for 10min, and removing slag.

The temperature of the aluminum liquid is raised to 730 ℃, and the aluminum liquid is poured into a sand mold for 3D printing, wherein the temperature of the sand mold is 60 ℃;

t6 heat treatment is carried out on the casting, and the specific process comprises the following steps: the solution temperature is 510 ℃, the solution time is 5h, the quenching medium is water, the temperature is 55 ℃, the artificial aging is carried out immediately after the quenching is finished, the aging temperature is 220 ℃, and the aging time is 8 h. Taking out and placing at room temperature for air cooling.

The wall thickness of the cast product was 4 mm.

FIG. 7 is the as-cast phase diagram of the aluminum alloy of example 3. from FIG. 7, it can be seen that the composition formula of the material is adapted to the heat conductivity of the 3D printing sand mold, and the structure is fine and uniform without coarse dendrites. FIG. 8 is an as-cast SEM photograph of the aluminum alloy of example 3, and it can be seen from FIG. 8 that the eutectic silicon size of the material is fine and uniform. FIG. 9 is a SEM image of the aluminum alloy in T6 state of example 3. As can be seen from FIG. 9, after the material is subjected to T6 heat treatment, the eutectic silicon is fine and round.

Example 4

An aluminum alloy material for high-performance thin-wall 3D printing sand casting comprises the following main components in percentage by mass: si: 7.53%, Mg: 0.40 percent; ti: 0.16 percent; sr: 0.034%; fe: 0.156%; zr: 0.16 percent; and (C) Sc: 0.4 percent; other inevitable impurity elements are less than or equal to 0.10 percent; the balance being Al.

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

step 2: adding an A356 aluminum ingot into a crucible, putting the crucible into a resistance furnace, heating the resistance furnace to 740 ℃ according to the sequence of raising the temperature by 100 ℃ each time, adding Al-10Zr intermediate alloy and Al-2Sc intermediate alloy after furnace burden is completely melted, and stirring for 5min by using a stirring rod;

and step 3: when the temperature of the aluminum liquid is stable at 720 ℃, adding Al-5Ti-B intermediate alloy, stirring until the intermediate alloy is completely melted, and standing for 8 min;

and 4, step 4: when the temperature rises to 710 ℃, adding Al-10Sr intermediate alloy, stirring until the intermediate alloy is completely melted, standing for 5min, and slagging off;

introducing high-purity argon gas for degassing, introducing gas for 5min, standing for 5min, and removing slag.

The temperature of the aluminum liquid is raised to 730 ℃, and the aluminum liquid is poured into a sand mold for 3D printing, wherein the temperature of the sand mold is 40 ℃;

t6 heat treatment is carried out on the casting, and the specific process comprises the following steps: the solution temperature is 540 ℃, the solution time is 4.2h, the quenching medium is water, the temperature is 70 ℃, the artificial aging is carried out immediately after the quenching is finished, the aging temperature is 180 ℃, and the aging time is 8.5 h. Taking out and placing at room temperature for air cooling.

The wall thickness of the cast product is 2 mm.

FIG. 10 is the as-cast phase diagram of the aluminum alloy of example 4. from FIG. 10, it can be seen that the composition formula of the material is adapted to the heat conductivity of the 3D printing sand mold, and the structure is fine and uniform without coarse dendrites. FIG. 11 is an as-cast SEM photograph of the aluminum alloy of example 4, and it can be seen from FIG. 11 that the eutectic silicon size of the material is fine and uniform. FIG. 12 is a SEM image of the aluminum alloy in T6 state of example 4, and it can be seen from FIG. 12 that the eutectic silicon is fine and round after the material is subjected to T6 heat treatment.

Example 5

An aluminum alloy material for high-performance thin-wall 3D printing sand casting comprises the following main components in percentage by mass: si: 6.5 percent; mg: 0.32 percent; ti: 0.10 percent; sr:0.01 percent; fe: 0.16 percent; zr: 0.6 percent; and (C) Sc: 0 percent; other inevitable impurity elements are less than or equal to 0.10 percent; the balance being Al.

and 4, step 4: when the temperature rises to 730 ℃, adding Al-10Sr intermediate alloy, stirring until the intermediate alloy is completely melted, standing for 5min, and slagging off;

introducing high-purity argon gas for degassing, introducing gas for 5min, standing for 15min, and removing slag.

The temperature of the aluminum liquid is raised to 730 ℃, and the aluminum liquid is poured into a sand mold for 3D printing, wherein the temperature of the sand mold is 100 ℃;

t6 heat treatment is carried out on the casting, and the specific process comprises the following steps: the solution temperature is 550 ℃, the solution time is 3h, the quenching medium is water, the temperature is 70 ℃, the artificial aging is carried out immediately after the quenching is finished, the aging temperature is 220 ℃, and the aging time is 8 h. Taking out and placing at room temperature for air cooling.

The wall thickness of the cast product was 12 mm.

FIG. 13 is the as-cast phase diagram of the aluminum alloy of example 5. from FIG. 13, it can be seen that the composition formula of the material is adapted to the heat conductivity of the 3D printing sand mold, and the structure is fine and uniform without coarse dendrites. FIG. 14 is an as-cast SEM photograph of the aluminum alloy of example 5, and it can be seen from FIG. 14 that the eutectic silicon size of the material is fine and uniform. FIG. 15 is a SEM image of the aluminum alloy T6 of example 5 in the state of T6, and it can be seen from FIG. 15 that the eutectic silicon is fine and round after the material is subjected to T6 heat treatment.

Example 6

An aluminum alloy material for high-performance thin-wall 3D printing sand casting comprises the following main components in percentage by mass: si: 6.9%, Mg: 0.4 percent; ti: 0.145 percent; sr: 0.04 percent; fe:0.1 percent; zr: 0.2 percent; and (C) Sc: 0.02 percent; other inevitable impurity elements are less than or equal to 0.10 percent; the balance being Al.

and 4, step 4: when the temperature is raised to 730 ℃, adding Al-10Sr intermediate alloy, stirring until the intermediate alloy is completely melted, standing for 5 minutes, and slagging off;

The temperature of the aluminum liquid is raised to 730 ℃, and the aluminum liquid is poured into a sand mold for 3D printing, wherein the temperature of the sand mold is 25 ℃;

t6 heat treatment is carried out on the casting, and the specific process comprises the following steps: the solution temperature is 480 ℃, the solution time is 8h, the quenching medium is water, the temperature is 4 ℃, the artificial aging is carried out immediately after the quenching is finished, the aging temperature is 180 ℃, and the aging time is 11 h. Taking out and placing at room temperature for air cooling.

The wall thickness of the cast product is 6 mm.

FIG. 16 is the as-cast phase diagram of the aluminum alloy of example 6. from FIG. 16, it can be seen that the composition formula of the material is adapted to the heat conductivity of the 3D printing sand mold, and the structure is fine and uniform without coarse dendrites. FIG. 17 is an as-cast SEM photograph of the aluminum alloy of example 6, and it can be seen from FIG. 17 that the eutectic silicon size of the material is fine and uniform. FIG. 18 is a SEM image of the aluminum alloy T6 of example 6 in a T6 state, and it can be seen from FIG. 18 that the eutectic silicon is fine and round after the material is subjected to T6 heat treatment.

Example 7

An aluminum alloy material for high-performance thin-wall 3D printing sand casting comprises the following main components in percentage by mass: si: 8%, Mg: 0.25 percent; ti: 0.15 percent; sr: 0.026%; fe: 0.14 percent; zr: 0.20 percent; and (C) Sc: 0.02 percent; other inevitable impurity elements are less than or equal to 0.10 percent; (ii) a The balance being Al.

introducing high-purity argon gas for degassing, introducing gas for 7min, standing for 7min, and removing slag.

The temperature of the aluminum liquid is raised to 730 ℃, and the aluminum liquid is poured into a sand mold for 3D printing, wherein the temperature of the sand mold is 50 ℃;

The wall thickness of the cast product is 8 mm.

Comparative example 1: comprises the following components in percentage by mass: si: 5.91%, Mg: 0.23 percent; ti: 0.146 percent; sr: 0.011 percent; fe: 0.136%; zr: 0.1 percent; and (C) Sc: 0.05 percent; the balance being Al.

t6 heat treatment is carried out on the casting, and the specific process comprises the following steps: the solid solution temperature is 480 ℃, the solid solution time is 8 hours, the quenching medium is water, the temperature is 4 ℃, the artificial aging is carried out immediately after the quenching is finished, the aging temperature is 160 ℃, and the aging time is 11 hours. Taking out and placing at room temperature for air cooling.

Comparative example 1 the cast article was cast with a wall thickness of 15 mm.

Comparative example 2: comprises the following components in percentage by mass: si: 8.31%, Mg: 0.43 percent; ti: 0.04 percent; sr: 0.05 percent; fe: 0.16 percent; zr: 0.15 percent; the balance being Al.

t6 heat treatment is carried out on the casting, and the specific process comprises the following steps: the solid solution temperature is 480 ℃, the solid solution time is 8 hours, the quenching medium is water, the temperature is 4 ℃, the artificial aging is carried out immediately after the quenching is finished, the aging temperature is 250 ℃, and the aging time is 11 hours. Taking out and placing at room temperature for air cooling.

Comparative example 2 the cast article poured had a wall thickness of 15 mm. As can be seen from the data in Table 1, the 3D printing sand casting aluminum alloy prepared in the embodiments 1 to 7 has yield strength of more than 250MPa, tensile strength of more than 290MPa, hardness of more than 100HB and elongation of more than 2%. The tensile strength and yield strength are much greater than those of comparative examples 1 and 2, and the data of elongation and hardness are both greater than those of comparative examples 1 and 2. The aluminum alloy is particularly suitable for thin-wall 3D printing sand casting, and can bring higher service safety and reduce maintenance cost.

The tensile mechanical property test at room temperature (GB/T228.1-2010) and the Brinell hardness test were performed on each of the examples and comparative examples, and the test results are shown in Table 1 below.

TABLE 1

As can be seen from the data in Table 1, the 3D printing sand casting aluminum alloy prepared in the embodiments 1 to 7 has yield strength of more than 250MPa, tensile strength of more than 290MPa, hardness of more than 100HB and elongation of more than 2%. The tensile strength and yield strength are much greater than those of comparative examples 1 and 2, and the data of elongation and hardness are both greater than those of comparative examples 1 and 2. The aluminum alloy is particularly suitable for thin-wall 3D printing sand casting, and can bring higher service safety and reduce maintenance cost.

The above examples are only preferred embodiments of the present invention, which are intended to be illustrative and not limiting, and those skilled in the art should understand that they can make various changes, substitutions and alterations without departing from the spirit and scope of the invention.

Claims

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;

(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.