CN114908275A

CN114908275A - Heat-treatment-free high-strength and high-toughness die-casting aluminum alloy, and preparation method and application thereof

Info

Publication number: CN114908275A
Application number: CN202210644049.5A
Authority: CN
Inventors: 宋东福; 周楠; 徐军; 夏鹏; 郑开宏
Original assignee: Institute of New Materials of Guangdong Academy of Sciences
Current assignee: Institute of New Materials of Guangdong Academy of Sciences
Priority date: 2022-06-08
Filing date: 2022-06-08
Publication date: 2022-08-16
Anticipated expiration: 2042-06-08
Also published as: CN114908275B

Abstract

The invention discloses a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy, a preparation method and application thereof, and relates to the technical field of aluminum alloys. The alloy comprises the following components in percentage by mass: 9.6-11.6% of Si, 0.67-0.82% of Fe0.67, 0-0.13% of Cr, 9-13% of Zn, 0.01-0.05% of Sr, 0.03-0.06% of RE, 0.01-0.02% of B, less than 0.01% of Mg, and the balance of aluminum and impurity elements, wherein the impurity elements are less than 0.15%; by regulating the content of each element, the aluminum alloy casting can be prepared without heat treatment, and the obtained casting has good tensile strength, yield strength and elongation, can be used for preparing new energy automobiles, and has wide application prospect.

Description

Heat-treatment-free high-strength and high-toughness die-casting aluminum alloy, and preparation method and application thereof

Technical Field

The invention relates to the technical field of aluminum alloy, in particular to a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy, and a preparation method and application thereof.

Background

The new energy automobile is the key point of future development, and the light weight of the automobile is the most direct and effective means at present under the important requirements of energy conservation and emission reduction and continuous improvement of long-term mileage of the new energy automobile. When the weight of the automobile is reduced by 10 percent, the endurance mileage is increased by 6 to 8 percent, and the energy consumption is reduced by 6 to 8 percent. The light weight is mainly started from three aspects of materials, processes, designs and the like, and the three components are gradually fused to promote the large-scale development of the component. The die-casting integration of the large-scale component greatly reduces the number of required production parts, obviously reduces the links of welding and gluing, greatly simplifies the whole production flow of the vehicle body, and obviously improves the production efficiency of the vehicle body. In order to satisfy the high elongation performance of the member, heat treatment is generally required, but as the size of the integrated casting becomes larger and the thickness variation becomes larger, deformation is likely to occur during heat treatment, and the yield is lowered. Therefore, it is required to develop a high-strength die-cast aluminum alloy material free from heat treatment.

CN114293058A discloses a preparation method of a high-strength and high-toughness heat-treatment-free material, which comprises the following steps: 5 to 8 percent of Si, 0.30 to 0.50 percent of Mg, 0.05 to 0.20 percent of Ti, 0.01 to 0.03 percent of Sr, less than or equal to 0.20 percent of Cu, less than or equal to 0.20 percent of Fe, less than or equal to 0.10 percent of Zn, 0.5 to 0.8 percent of Mn0.05 to 0.20 percent of Nb, 0.01 to 0.03 percent of B, 0.05 to 0.20 percent of Cr, 0.06 to 0.15 percent of La, 0.04 to 0.10 percent of Ce, and less than or equal to 0.2 percent of total impurity. The tensile strength of the cylinder cover prepared by vacuum die casting reaches 260MPa, the yield strength is 150MPa, and the elongation is more than 10%. However, the strength of the cast article is to be improved.

CN114164362A discloses a heat-treatment-free high-strength and high-toughness aluminum alloy and a forming method thereof, wherein the aluminum alloy comprises the following components in percentage by mass: 8.5-11.5% of Si, 0.05-0.5% of Cu, 0.05-0.5% of Mg, 0.1-0.5% of Mo, 0.005-0.1% of Sr, 0.005-0.1% of B, 0.05-0.3% of Cd, 0.05-0.25% of Zr, and the balance of Al and inevitable impurities. The invention refines the alloy structure by compositely adding B and Sr, avoids the poisoning phenomenon of B and Sr by adding Mo, and refines the eutectic silicon size and submicron level. The tensile strength of the heat-treatment-free casting can reach 300-400MPa, the yield strength is 180-320MPa, and the elongation is 8-21%. The alloy of the invention has good strength, toughness and toughness, but contains a certain amount of toxic element Cd.

CN113755722A discloses a high-strength and high-toughness heat-treatment-free aluminum alloy material: 8.0 to 10.5 percent of Si, less than or equal to 0.15 percent of Fe, 0.05 to 0.3 percent of Mg0.05 to 0.3 percent of Zn0.05 to 0.3 percent of Mn0.3 to 0.6 percent of Cu, less than or equal to 0.1 percent of Cu, 0.05 to 0.15 percent of Ti0.05 percent of Ca, less than or equal to 0.005 percent of Sr0.005 to 0.030 percent of Zr0.1 to 0.3 percent of Mo0.01 to 0.1 percent of V, 0.01 to 0.3 percent of Cr, less than or equal to 0.002 percent of Na, less than or equal to 0.002 percent of P, less than or equal to 0.01 percent of Cd, less than or equal to 0.001 percent of Li, less than or equal to 0.0025 percent of B, less than or equal to 0.05 percent of Ga, and the balance of Al and inevitable impurities. The tensile strength of the casting prepared by vacuum die casting is more than 250MPa, the yield is more than 134MPa, and the elongation is more than 13%. However, the strength of the alloy of this invention is to be improved.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The invention aims to provide a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy, a preparation method and application thereof, and aims to prepare die-casting parts with excellent tensile strength, yield strength and elongation without heat treatment.

The invention is realized by the following steps:

in a first aspect, the invention provides a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy, which comprises the following components in percentage by mass: 9.6 to 11.6 percent of Si, 0.67 to 0.82 percent of Fe, 0 to 0.15 percent of Cr, 9 to 13 percent of Zn, 0.01 to 0.05 percent of Sr, 0.03 to 0.06 percent of RE, 0.01 to 0.02 percent of B, less than 0.01 percent of Mg, and the balance of aluminum and impurity elements, wherein the impurity elements are less than 0.15 percent;

wherein the total content of Fe and Cr is 0.8-0.9%, and the total content of Sr and RE is not more than 0.09%.

In an alternative embodiment, the alloy composition comprises, in mass percent: 10.5-11.0% of Si, 0.70-0.80% of Fe, 0.05-0.12% of Cr, 10-12% of Zn, 0.02-0.04% of Sr, 0.04-0.05% of RE, 0.01-0.02% of B, less than 0.01% of Mg, and the balance of aluminum and impurity elements, wherein the impurity elements are less than 0.15%.

In alternative embodiments, RE is selected from at least one of La, Ce, Er.

In a second aspect, the present invention provides a method for producing a heat-treatment-free high-toughness die-cast aluminum alloy according to any one of the foregoing embodiments, including: the high-strength high-toughness die-casting aluminum alloy free of heat treatment in any one of the preceding embodiments is subjected to batching, smelting and casting.

In an alternative embodiment, the process of smelting comprises: firstly, melting industrial pure aluminum, a Si agent, a Fe agent and an Al-Cr intermediate alloy in a melting furnace, and controlling the temperature rise to be 750-800 ℃; adding Zn ingots, and reducing the temperature of the melt to 720-740 ℃; pressing Al-Sr-RE intermediate alloy and Al-B intermediate alloy into a melt after refining;

preferably, the industrial pure aluminum, the Si agent, the Fe agent, the Al-Cr intermediate alloy, the Zn ingot, the Al-Sr-RE intermediate alloy and the Al-B intermediate alloy are preheated before being added into the melting furnace, and the preheating temperature is controlled to be 200-250 ℃.

In an alternative embodiment, the refining process comprises: introducing a refining agent by taking preheated inert gas as a carrier, wherein the mass ratio of the introduced amount of the refining agent to the melt is 0.06-0.2: 100;

preferably, graphite snorkels are used to traverse the melt to provide adequate contact of the refining agent with the melt.

In an optional embodiment, sampling test is carried out and chemical components of the melt are finely adjusted to enable the element content to meet requirements before refining is carried out after the temperature of the melt is reduced to 720-740 ℃, and then the melt is transferred into a refining holding furnace for refining.

In an alternative embodiment, standing is carried out after refining, scum close to the surface of the melt at the furnace mouth is removed, and then preheated Al-Sr-RE intermediate alloy and Al-B intermediate alloy are pressed into the melt by a titanium alloy bell jar and are uniformly stirred; and (4) removing scum after standing, and then performing casting molding.

In an alternative embodiment, the cast molding is a molding process in which the melt is introduced into an ingot casting machine or ladle.

In a third aspect, the invention provides an application of the heat-treatment-free high-toughness die-casting aluminum alloy in any one of the previous embodiments or the heat-treatment-free high-toughness die-casting aluminum alloy prepared by the preparation method in any one of the previous embodiments in manufacturing new energy automobiles.

The invention has the following beneficial effects: the prepared aluminum alloy contains Si, Fe, Cr, Zn, Sr, RE and B, and an aluminum alloy casting can be prepared under the condition of not performing heat treatment by regulating the content of each element.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The embodiment of the invention provides a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy which comprises the following components in percentage by mass: 9.6 to 11.6 percent of Si, 0.67 to 0.82 percent of Fe, 0 to 0.15 percent of Cr, 9 to 13 percent of Zn, 0.01 to 0.05 percent of Sr, 0.03 to 0.06 percent of RE, 0.01 to 0.02 percent of B, less than 0.01 percent of Mg, and the balance of aluminum and impurity elements, wherein the impurity elements are less than 0.15 percent; wherein the total content of Fe and Cr is 0.8-0.9%, and the total content of Sr and RE is not more than 0.09%.

The content of Si, Fe, Cr, Zn, Sr, RE and B elements is optimized by the inventor, the die-casting aluminum alloy can be prepared on the premise of not carrying out heat treatment, and the comprehensive performance of the aluminum alloy is excellent.

Specifically, the effects of the elements in the aluminum alloy composition provided by the embodiment of the invention are as follows:

the Si content in the aluminum alloy composition provided by the embodiment of the invention is close to Al-Si eutectic point (12.6%), belongs to eutectic Al-Si alloy, has excellent mold filling performance, is particularly suitable for molding large-size, thin-wall and complex-structure die castings, and is also suitable for sand casting of large-size components.

Fe is one of indispensable elements in the die-casting aluminum alloy, the higher Fe content can avoid die sticking, the size precision of the casting can be ensured, and the die is improvedService life. According to elimination of beta-Al ₅ The relation between the critical Fe content required by the FeSi phase and the Si content is that when the Si content is 9.6-11.6%, the critical Fe content is about 0.67%. Therefore, when the critical Fe content in the alloy is lower than 0.8 percent, Cr element is adopted to fill up the critical Fe content, and the content of Cr and Fe is higher than 0.8 percent, so that the die bonding-free characteristic of the alloy is ensured.

The function of B is mainly to refine the crystal grains, and the effect of refining the crystal grains can be well achieved under the condition of less using amount. In the process of die casting, the temperature of the melt is rapidly reduced in the charging barrel stage, particularly the melt in contact with a die promotes the nucleation and growth of partial alpha-Al, and the alpha-Al is rapidly sprayed to a cavity along with the melt, so that a certain proportion of alpha-Al coarse crystals are formed in a casting, and the performance of the alloy is influenced. The addition of B can reduce the number of coarse crystals and is beneficial to improving the plasticity of the casting.

Zn has a high solid solubility in Al alloys and is usually present in solid solution, strengthening the matrix. When the Zn content is higher (more than or equal to 3 percent), the cast aluminum alloy has the characteristic of quenching structure, has higher strength without heat treatment and also has high plasticity of the quenching structure. Therefore, Zn has a main effect of improving the toughness of the alloy and having a heat treatment-free property, but if the Zn content is too high, pure Zn particles are likely to be precipitated, which is not favorable for improving the toughness of the alloy.

Sr is a main modifier of the eutectic silicon, RE is used as an auxiliary element for Sr modification, the modification efficiency of the eutectic silicon is further improved, eutectic silicon particles with smaller size and higher sphericity are obtained, the precipitation strengthening effect of Si is improved, the cutting crack and stress concentration on a matrix are reduced, and the toughness of a casting is improved.

Mg and Al, Zn, Si and other elements form a nano-scale reinforcing phase, so that the strength of the alloy is obviously improved, but the plasticity is reduced, and the casting is not favorable for obtaining higher toughness.

In order to further improve the comprehensive performance of the aluminum alloy, the inventor optimizes the dosage of each element: the alloy comprises the following components in percentage by mass: 10.5-11.0% of Si, 0.70-0.80% of Fe, 0.05-0.12% of Cr, 10-12% of Zn, 0.02-0.04% of Sr, 0.04-0.05% of RE, 0.01-0.02% of B, less than 0.01% of Mg, and the balance of aluminum and impurity elements, wherein the impurity elements are less than 0.15%.

In some embodiments, RE is selected from at least one of La, Ce, Er, and may be one, or two or three.

The embodiment of the invention provides a preparation method of a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy, which comprises the following steps:

s1, preparing the ingredients

The components of the heat-treatment-free high-strength and high-toughness die-casting aluminum alloy provided by the embodiment of the invention are mixed, so that the components of the prepared aluminum alloy casting meet the requirements.

The main raw materials comprise: the alloy comprises industrial pure aluminum, a Si agent, a Fe agent, a Zn ingot, an Al-Cr intermediate alloy, an Al-Sr-RE intermediate alloy and an Al-B intermediate alloy. Namely, Sr and RE are added in the form of Al-Sr-RE, and other raw materials are added by adopting metal pure raw materials or aluminum intermediate alloy.

S2, smelting

The smelting process comprises the following steps: firstly, melting industrial pure aluminum, an Si agent, an Fe agent and an Al-Cr intermediate alloy in a melting furnace, and controlling the temperature rise to be 750-800 ℃ (such as 750 ℃, 760 ℃, 770 ℃, 780 ℃, 790 ℃, 800 ℃ and the like); adding Zn ingot, and reducing the temperature of the melt to 720-740 ℃ (such as 720 ℃, 725 ℃, 730 ℃, 735 ℃, 740 ℃ and the like); after refining, pressing the Al-Sr-RE intermediate alloy and the Al-B intermediate alloy into the melt. The order of adding the raw materials is preferably the order mentioned above, so as to avoid the adverse effect of high-temperature smelting on Sr and RE.

In some embodiments, the commercially pure aluminum, Si agent, Fe agent, Al-Cr master alloy, Zn ingot, Al-Sr-RE master alloy, and Al-B master alloy are preheated before being added into the melting furnace, with the preheating temperature being controlled at 200-250 ℃. The flue gas preheating can be adopted, and other preheating modes can also be adopted, which are not limited herein.

In some embodiments, the refining comprises: the preheated inert gas is used as a carrier, a refining agent is introduced, the mass ratio of the introduced quantity of the refining agent to the melt is 0.06-0.2:100, such as 0.10:100, 0.15:100, 0.20:100 and the like, and the temperature of the inert gas is 70-100 ℃. The type of the refining agent is not limited, and the refining agent can be prepared from conventional aluminum alloy products. Preferably, graphite snorkels are used to traverse the melt to allow sufficient contact between the refining agent and the melt, and "traverse the melt" means that gas is passed through the melt in the furnace to ensure sufficient contact between the refining agent and the melt.

In order to control the composition of a product more accurately, sampling test is carried out and chemical components of the melt are finely adjusted to enable the content of elements to meet requirements before the melt is refined after the temperature of the melt is reduced to 720-740 ℃, and then the melt is transferred into a refining holding furnace for refining.

In some embodiments, standing is carried out after refining, scum close to the surface of the melt at the furnace mouth is removed, and then preheated Al-Sr-RE intermediate alloy and Al-B intermediate alloy are pressed into the melt by a titanium alloy bell jar and are slightly stirred uniformly; after standing, scum is removed, and the melt is cast and molded.

In other embodiments, the manner of pressing the master alloy into the melt may be other manners, and is not limited herein.

S3, casting and forming

The casting forming method is not limited, and the existing forming method can be adopted, and the targeted adjustment can be carried out according to the size and the shape of the required product.

Specifically, the casting molding is to introduce the melt into an ingot casting machine or a casting ladle to obtain a heat-treatment-free die-casting aluminum alloy ingot or direct-supply casting molding device.

The aluminum alloy casting prepared by the embodiment of the application has good tensile strength, yield strength and elongation, and can be used for preparing new energy automobiles.

The features and properties of the present invention are described in further detail below with reference to examples.

Example 1

The embodiment provides a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy which comprises the following components in percentage by mass: 9.6 percent of Si, 0.67 percent of Fe, 0.13 percent of Cr, 10 percent of Zn, 0.01 percent of Sr, 0.05 percent of RE, 0.015 percent of B, the balance of aluminum and impurity elements, and the impurity elements are less than 0.15 percent.

The embodiment also provides a preparation method of the heat-treatment-free high-strength and high-toughness die-casting aluminum alloy, which is prepared according to the composition of the alloy elements provided by the embodiment, the raw materials comprise industrial pure aluminum, a Si agent, a Fe agent, a Zn ingot, an Al-Cr intermediate alloy, an Al-Sr-RE intermediate alloy and an Al-B intermediate alloy, and the preparation process comprises the following steps:

(1) preheating the industrial pure aluminum, the Si agent, the Fe agent and the Al-Cr intermediate alloy to 220 ℃ by utilizing flue gas, putting the preheated industrial pure aluminum, the Si agent, the Fe agent and the Al-Cr intermediate alloy into a melting furnace, and heating to 770 ℃.

(2) After the raw materials are completely melted, adding a preheated Zn ingot (the preheating temperature is 220 ℃, the same is applied below), and reducing the temperature of the melt to 720 ℃; sampling to test the chemical components of the melt, and transferring the melt to a refining holding furnace after the components are qualified.

(3) High-purity inert gas with the temperature of 80 ℃ is taken as a carrier, 0.15 percent of refining agent is introduced, and a graphite vent pipe is adopted to pass through the melt, so that the refining agent is fully contacted with the melt.

(4) After standing for 30min, removing scum close to the surface of the melt at the furnace mouth; the preheated Al-Sr-RE, Al-B master alloy was then pressed into the melt (preheating temperature 220 ℃ C., the same applies below) with a titanium alloy bell jar and stirred gently.

(5) And (3) after the melt is kept stand for 20min, removing scum, and introducing the melt into an ingot casting machine to obtain a heat-treatment-free die-casting aluminum alloy ingot.

Example 2

The embodiment provides a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy which comprises the following components in percentage by mass: 10.5 percent of Si, 0.74 percent of Fe, 0.09 percent of Cr, 13.0 percent of Zn, 0.05 percent of Sr, 0.04 percent of RE, 0.01 percent of B, the balance of aluminum and impurity elements, and the impurity elements are less than 0.15 percent.

(1) preheating industrial pure aluminum, a Si agent, a Fe agent and an Al-Cr intermediate alloy to 220 ℃ by utilizing smoke, putting the preheated industrial pure aluminum, the Si agent, the Fe agent, the Al-Cr intermediate alloy and other raw materials into a melting furnace, and heating to 790 ℃.

(2) After the raw materials are completely melted, adding preheated Zn ingots, reducing the temperature of the melt to 730 ℃, sampling and testing the chemical components of the melt, and transferring the melt to a refining holding furnace after the components are qualified.

(3) High-purity inert gas at 100 ℃ is taken as a carrier, 0.1 percent of refining agent is introduced, and a graphite vent pipe is adopted to pass through the melt, so that the refining agent is fully contacted with the melt.

(4) After standing for 15min, removing floating slag on the surface of the melt close to the furnace mouth, pressing preheated Al-Sr-RE and Al-B intermediate alloy into the melt by using a titanium alloy bell jar, and slightly stirring.

(5) And (3) after the melt is kept stand for 30min, removing scum, introducing the melt into a casting ladle, and directly supplying the melt to a die casting machine to obtain the heat-treatment-free high-strength and high-toughness aluminum alloy casting.

Example 3

The embodiment provides a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy which comprises the following components in percentage by mass: 11.5 percent of Si, 0.80 percent of Fe, 9.0 percent of Zn, 0.03 percent of Sr, 0.04 percent of RE, 0.02 percent of B, the balance of aluminum and impurity elements, and the impurity elements are less than 0.15 percent.

(1) preheating industrial pure aluminum, a Si agent, a Fe agent and an Al-Cr intermediate alloy to 220 ℃ by utilizing flue gas, putting the preheated industrial pure aluminum, the Si agent, the Fe agent and other raw materials into a melting furnace, and heating to 800 ℃.

(2) After the raw materials are completely melted, adding preheated Zn ingots, and reducing the temperature of the melt to 730 ℃; sampling to test the chemical components of the melt, and transferring the melt to a refining holding furnace after the components are qualified.

(3) High-purity inert gas at 90 ℃ is taken as a carrier, 0.06% of refining agent is introduced, and a graphite vent pipe is adopted to pass through the melt, so that the refining agent is fully contacted with the melt.

(4) And (3) standing for 30min, removing floating slag on the surface of the melt close to the furnace mouth, pressing preheated Al-Sr-RE and Al-B intermediate alloy into the melt by using a titanium alloy bell jar, and slightly stirring.

(5) And (3) after the melt is kept stand for 15min, removing scum, and introducing the melt into an ingot casting machine to obtain the heat-treatment-free die-casting aluminum alloy ingot.

Example 4

The embodiment provides a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy which comprises the following components in percentage by mass: 11.0 percent of Si, 0.76 percent of Fe, 0.06 percent of Cr, 11.5 percent of Zn, 0.02 percent of Sr, 0.05 percent of RE, 0.02 percent of B, the balance of aluminum and impurity elements, and the impurity elements are less than 0.15 percent.

(2) After the raw materials are completely melted, adding preheated Zn ingots, and reducing the temperature of the melt to 740 ℃; sampling and testing the chemical components of the melt, and transferring the melt to a refining holding furnace after the components are qualified.

(3) High-purity inert gas at 70 ℃ is taken as a carrier, 0.12 percent of refining agent is introduced, and a graphite vent pipe is adopted to pass through the melt, so that the refining agent is fully contacted with the melt.

(4) After standing for 20 ℃, removing scum on the surface of the melt close to the furnace mouth, pressing preheated Al-Sr-RE and Al-B intermediate alloy into the melt by using a titanium alloy bell jar, and slightly stirring.

(5) And after the melt is melted for 25min, removing scum, introducing the melt into a casting ladle, and directly supplying the melt to a die casting machine to obtain a die casting.

Comparative example 1

The comparative example provides a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy and a preparation method thereof, and only differs from the embodiment 1 in that: the composition of comparative example 1 contained no RE element, and Sr was added as an Al-Sr master alloy.

Comparative example 2

The comparative example provides a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy and a preparation method thereof, and only differs from the embodiment 1 in that: comparative example 2 had a Mg content of 0.3%;

comparative example 3

The comparative example provides a heat-treatment-free high-strength and high-toughness die-casting aluminum alloy and a preparation method thereof, and only differs from the embodiment 1 in that: comparative example 3 has a B content of 0%;

test example 1

The die castings provided in examples 1 to 4 and comparative examples 1 to 3 were measured for tensile mechanical properties, respectively, and the results are shown in the following table:

TABLE 1 tensile mechanical Properties of the as-die-cast alloys

Group of	Tensile strength (MPa)	Yield strength (MPa)	Elongation (%)
				Comparative example 1	355	245	4.0
Comparative example 2	380	300	1.2
				Comparative example 3	360	240	6.0
Example 1	365	245	7.5
				Example 2	385	270	6.5
Example 3	355	235	8.5
				Example 4	370	255	7.0

In conclusion, the heat-treatment-free high-strength and high-toughness die-casting aluminum alloy, and the preparation method and the application thereof are provided, the prepared aluminum alloy contains Si, Fe, Cr, Zn, Sr, RE and B, and an aluminum alloy casting can be prepared under the condition of no heat treatment by regulating the content of each element, and the obtained casting has good tensile strength, yield strength and elongation, wherein the tensile strength is more than or equal to 350MPa, the yield strength is more than or equal to 230MPa, and the elongation is more than or equal to 6.0%.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The heat treatment-free high-strength and high-toughness die-casting aluminum alloy is characterized by comprising the following components in percentage by mass: 9.6 to 11.6 percent of Si, 0.67 to 0.82 percent of Fe, 0 to 0.15 percent of Cr, 9 to 13 percent of Zn, 0.01 to 0.05 percent of Sr, 0.03 to 0.06 percent of RE, 0.01 to 0.02 percent of B, less than 0.01 percent of Mg, and the balance of aluminum and impurity elements, wherein the impurity elements are less than 0.15 percent;

2. The heat-treatment-free high-strength and high-toughness die-casting aluminum alloy as claimed in claim 1, wherein the alloy composition comprises the following components in percentage by mass: 10.5-11.0% of Si, 0.70-0.80% of Fe, 0.05-0.12% of Cr, 10-12% of Zn, 0.02-0.04% of Sr, 0.04-0.05% of RE, 0.01-0.02% of B, less than 0.01% of Mg, and the balance of aluminum and impurity elements, wherein the impurity elements are less than 0.15%.

3. The heat-treatment-free high-toughness die-casting aluminum alloy according to claim 1 or 2, wherein RE is at least one selected from La, Ce and Er.

4. A method for preparing the heat-treatment-free high-strength high-toughness die-casting aluminum alloy as set forth in any one of claims 1 to 3, which comprises the following steps: the heat-treatment-free high-strength and high-toughness die-casting aluminum alloy as recited in any one of claims 1 to 3 is subjected to batching, smelting and casting forming.

5. The method of claim 4, wherein the smelting comprises: firstly, melting industrial pure aluminum, a Si agent, a Fe agent and an Al-Cr intermediate alloy in a melting furnace, and controlling the temperature rise to be 750-800 ℃; adding Zn ingots, and reducing the temperature of the melt to 720-740 ℃; pressing Al-Sr-RE intermediate alloy and Al-B intermediate alloy into a melt after refining;

6. The method of manufacturing according to claim 5, wherein the refining process comprises: introducing a refining agent by taking preheated inert gas as a carrier, wherein the mass ratio of the introduced amount of the refining agent to the melt is 0.06-0.2: 100;

preferably, graphite snorkels are used to traverse the melt to bring the refining agent into intimate contact with the melt;

preferably, the temperature of the inert gas is 70-100 ℃.

7. The preparation method of the alloy material according to claim 6, wherein before refining after the temperature of the melt is reduced to 720-740 ℃, sampling test is carried out, the chemical composition of the melt is finely adjusted to enable the element content to meet requirements, and then the melt is transferred into a refining holding furnace for refining.

8. The preparation method according to claim 6, characterized in that, after refining, standing is carried out to remove dross close to the surface of the melt at the furnace mouth, and then preheated Al-Sr-RE intermediate alloy and Al-B intermediate alloy are pressed into the melt by a titanium alloy bell jar and are stirred uniformly; and (4) removing scum after standing, and then performing casting molding.

9. The method of claim 8, wherein the cast molding is a molding process in which the melt is introduced into an ingot casting machine or a ladle.

10. Use of the heat-treatment-free high-toughness die-casting aluminum alloy as defined in any one of claims 1 to 3 or the heat-treatment-free high-toughness die-casting aluminum alloy prepared by the preparation method as defined in any one of claims 4 to 9 in manufacturing new energy automobiles.