阅读说明：本技术 高导热高强度压铸铝合金及其制备方法 (High-heat-conductivity high-strength die-casting aluminum alloy and preparation method thereof ) 是由 于永乐 陈琦 杜燕军 于 2020-06-17 设计创作，主要内容包括：本申请公开高导热高强度压铸铝合金及其制备方法,其中所述高导热高强度压铸铝合金包括：12.0～12.5重量％的硅、0.45～0.55重量％的铁、0.25～0.3重量％的镁、最多0.1重量％的铜、最多0.2重量％的锌、最多0.02重量％的钛、0.01～0.03重量％的锶、最多0.1重量％其它单个元素,其余为铝。(The application discloses high heat conduction high strength die-casting aluminum alloy and preparation method thereof, wherein the high heat conduction high strength die-casting aluminum alloy includes: 12.0 to 12.5% by weight of silicon, 0.45 to 0.55% by weight of iron, 0.25 to 0.3% by weight of magnesium, up to 0.1% by weight of copper, up to 0.2% by weight of zinc, up to 0.02% by weight of titanium, 0.01 to 0.03% by weight of strontium, up to 0.1% by weight of other individual elements, the remainder being aluminium.)

1. High heat conduction high strength die casting aluminum alloy, wherein high heat conduction high strength die casting aluminum alloy includes: 12.0 to 12.5% by weight of silicon, 0.45 to 0.55% by weight of iron, 0.25 to 0.3% by weight of magnesium, up to 0.1% by weight of copper, up to 0.2% by weight of zinc, up to 0.02% by weight of titanium, 0.01 to 0.03% by weight of strontium, up to 0.1% by weight of other individual elements, the remainder being aluminium.

2. The high thermal conductivity high strength die cast aluminum alloy of claim 1, wherein the high thermal conductivity high strength die cast aluminum alloy includes 0.2 to 0.3 weight percent boron.

3. The high-thermal-conductivity high-strength die-casting aluminum alloy according to claim 2, wherein the ratio of boron to titanium is 1-1.25.

4. The high thermal conductivity and high strength die casting aluminum alloy as claimed in claim 1, wherein the chemical element B is selected from the group consisting of Ti, V and Cr as impurities in the high thermal conductivity and high strength die casting aluminum alloyCombined to form TiB₂、V₂B₃、Cr₂B boride precipitation.

5. The preparation method of the high-heat-conductivity high-strength die-casting aluminum alloy is characterized by comprising the following steps of:

(1) adding an aluminum ingot and silicon into a smelting container for melting;

(2) when the temperature of the aluminum liquid reaches 710-720 ℃, adding 12.0-12.5 wt% of silicon, 0.45-0.55 wt% of iron, 0.25-0.3 wt% of magnesium ingot, 0.1 wt% of copper at most, 0.2 wt% of zinc at most, 0.02 wt% of titanium at most, 0.2-0.3 wt% of boron, 0.01-0.03 wt% of strontium and 0.1 wt% of other single elements into the aluminum liquid, heating the aluminum liquid to 730-740 ℃, and preserving the heat for at least 15 minutes to melt all alloys;

(3) when the temperature of the aluminum liquid is reduced to 710-730 ℃, pressing a special rare earth refining agent for the aluminum alloy into the aluminum alloy for refining; and

(4) and (3) modifying and degassing, specifically, pressing Al-Sr and Al-B into the aluminum liquid for modification when the temperature of the aluminum liquid is 710-720 ℃, and then introducing nitrogen into the aluminum liquid for degassing for a preset time.

6. The method for preparing a high-strength cast aluminum alloy according to claim 5, wherein the refining is performed by stirring the alloy up and down until the alloy is sufficiently refined, standing the alloy for a predetermined time to sufficiently float or sink the inclusions, and then removing the slag.

7. The method for preparing a high-strength cast aluminum alloy according to claim 6, wherein the method is performed for 5 to 10 minutes.

8. The method of making a high strength cast aluminum alloy article of claim 6, wherein the nitrogen is applied for a period of at least 10 minutes.

9. The method for preparing a high strength cast aluminum alloy according to claim 5, wherein the special rare earth refining agent used in step (3) is a sodium-free rare earth refining agent.

Technical Field

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

Background

Nowadays, the casting molding technology is one of the most commonly used molding methods for metal parts and components, and is widely used in various industries at present. The die-casting aluminum alloy component is the most common casting component and has the advantages of light weight, complex structure, easiness in recycling, low cost and the like.

Disclosure of Invention

An object of the present invention is to provide a high thermal conductivity high strength die-cast aluminum alloy, wherein the high thermal conductivity high strength die-cast aluminum alloy has a tensile yield limit rp0.2 of >140MPa and at the same time a elongation at break a of > 5%, a tensile strength Rm of >290MPa, a brinell hardness of >70HB in an as-cast state, and has a high thermal conductivity, which can be used for manufacturing communication products having a complicated structure, an uneven rear wall and a thin overall wall thickness.

Another object of the present invention is to provide a high thermal conductivity and high strength die-casting aluminum alloy, wherein the high thermal conductivity and high strength die-casting aluminum alloy has good comprehensive properties, and has the advantages of low density, high strength, good electrical and thermal conductivity, simple processing, etc., so as to better satisfy the requirements of product structure and heat dissipation.

Another object of the present invention is to provide a high thermal conductivity high strength die-cast aluminum alloy having good corrosion resistance and fatigue resistance.

To achieve at least one of the above objects of the present invention, the present invention provides a high thermal conductivity high strength die-cast aluminum alloy, wherein the high thermal conductivity high strength die-cast aluminum alloy comprises: 12.0 to 12.5% by weight of silicon, 0.45 to 0.55% by weight of iron, 0.25 to 0.3% by weight of magnesium, up to 0.1% by weight of copper, up to 0.2% by weight of zinc, up to 0.02% by weight of titanium, 0.01 to 0.03% by weight of strontium, up to 0.1% by weight of other individual elements, the remainder being aluminium.

According to an embodiment of the invention, the high-thermal-conductivity high-strength die-casting aluminum alloy comprises 0.2-0.3 wt% of boron.

According to an embodiment of the present invention, the ratio of boron to titanium is between 1 and 1.25.

According to an embodiment of the present invention, the chemical element B is combined with the impurity elements Ti, V and Cr in the high thermal conductivity high strength die-casting aluminum alloy to form TiB₂、V₂B₃、Cr₂B boride precipitation.

According to another aspect of the present invention to achieve at least one of the above objects, the present invention provides a method for preparing a high thermal conductivity high strength die-cast aluminum alloy, comprising the steps of:

(1) adding an aluminum ingot and silicon into a smelting container for melting;

(2) when the temperature of the aluminum liquid reaches 710-720 ℃, adding 12.0-12.5 wt% of silicon, 0.45-0.55 wt% of iron, 0.25-0.3 wt% of magnesium ingot, 0.1 wt% of copper at most, 0.2 wt% of zinc at most, 0.02 wt% of titanium at most, 0.2-0.3 wt% of boron, 0.01-0.03 wt% of strontium and 0.1 wt% of other single elements into the aluminum liquid, heating the aluminum liquid to 730-740 ℃, and preserving the heat for at least 15 minutes to melt all alloys;

(3) when the temperature of the aluminum liquid is reduced to 710-730 ℃, pressing a special rare earth refining agent for the aluminum alloy into the aluminum alloy for refining; and

(4) and (3) modifying and degassing, specifically, pressing Al-Sr and Al-B into the aluminum liquid for modification when the temperature of the aluminum liquid is 710-720 ℃, and then introducing nitrogen into the aluminum liquid for degassing for a preset time.

According to one embodiment of the invention, in the refining process, the alloy is stirred up and down until the alloy is fully refined, and is kept still for a preset time, so that the inclusion is fully floated or sunk, and then the slag is pulled out.

According to an embodiment of the invention, the mixture is allowed to stand for 5 to 10 minutes.

According to one embodiment of the invention, the nitrogen is introduced for a period of at least 10 minutes.

According to an embodiment of the present invention, the special rare earth refining agent adopted in step (3) is a sodium-free rare earth refining agent.

Further objects and advantages of the invention will be fully apparent from the ensuing description and understanding.

These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description.

Detailed Description

The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.

According to a preferred embodiment of the invention, the die-casting aluminum alloy with high thermal conductivity and high strength can be used for manufacturing communication products with complex structures, uneven rear walls and thinner overall wall thickness.

The high-heat-conductivity high-strength die-casting aluminum alloy comprises: 12.0 to 12.5 wt.% silicon, 0.45 to 0.55 wt.% iron, 0.25 to 0.3 wt.% magnesium, 0.1 wt.% copper at most, 0.2 wt.% zinc at most, 0.02 wt.% titanium at most, 0.2 to 0.3 wt.% boron, 0.01 to 0.03 wt.% strontium, the ratio of boron to titanium being between 1 and 1.25, 0.1 wt.% other individual elements at most, and the balance aluminum.

The preparation steps of the cast aluminum alloy with high thermal conductivity are as follows:

(1) preparing materials and cleaning a furnace. Specifically, the materials are prepared according to the proportion of alloy components, the furnace needs to be cleaned after the materials are prepared, the alloy elements are added in the form of pure metal or master alloy, the Si element is added in the form of simple substance 3303 silicon, the Mg element is added in the form of pure Mg ingot, the Sr element is added in the form of Sr master alloy, and the B element is added in the form of B master alloy;

(2) melting an aluminum ingot: after the surface of a pure aluminum ingot is cleaned, putting the pure aluminum ingot and 3303 silicon into a resistance crucible for heating and smelting, and controlling the temperature of aluminum liquid to be 710-730 ℃;

(3) adding a master alloy: when the temperature of the aluminum liquid reaches 710-720 ℃, pressing the dried magnesium ingot into the aluminum liquid by using a bell jar, heating the aluminum liquid to 730-740 ℃, and preserving the heat for at least 15 minutes to ensure that the added intermediate alloy is completely melted;

(4) and (5) refining. Specifically, when the temperature of aluminum liquid is reduced to 710-730 ℃, a special rare earth refining agent for aluminum alloy is pressed into the aluminum alloy by using a bell jar for refining, and the bell jar is stirred up and down in the refining process until the alloy is fully refined; standing for 5 minutes to enable the impurities to sufficiently float or sink, and then pulling out the slag;

(5) modification and degassing: and (3) modifying the aluminum liquid at the temperature of 710-720 ℃, pressing Al-Sr and Al-B into the aluminum liquid by using a bell jar to modify, then introducing nitrogen into the aluminum liquid by using a carbon rod to degas, degassing for at least 10 minutes, standing for at least 10 minutes, drawing out slag after standing, and removing surface oxide skin.

TABLE 1 Properties of the high thermal conductivity, high strength die cast aluminum alloy in steady state, worthy of different examples

In the high-heat-conductivity high-strength die-casting aluminum alloy, due to the uniformity of microstructure, the fluidity and the solidification feeding characteristic of an alloy melt are greatly improved, and the high-heat-conductivity high-strength die-casting aluminum alloy is particularly suitable for products with extremely complex shapes and concentrated thin walls and thick walls in one component.

In the high-heat-conductivity high-strength die-casting aluminum alloy, a sodium-free rare earth refining agent with the patent number of ZL 201610184371.9 is adopted, so that the purity of aluminum liquid can be improved, the deterioration of strontium is promoted, the loss of strontium content in the aluminum liquid is reduced, and the effect of improving the heat conductivity of the aluminum alloy is achieved; the residual rare earth is used as a genetic factor in the genetic process of the aluminum alloy casting tissue, and has positive effects on the positive genetic effect of the metallurgical foundry returns tissue performance and the inhibition of accidental defects of the aluminum alloy microstructure, so that the use proportion of the foundry returns can be improved under the condition of ensuring the heat conduction of the aluminum alloy material.

In the high-heat-conductivity and high-strength die-casting aluminum alloy, the uniformity of the microstructure is benefited, the elongation stability of a pressure casting product is greatly improved, and the dimensional stability is correspondingly improved.

In the high-heat-conductivity high-strength die-casting aluminum alloy, the content of silicon in the high-heat-conductivity high-strength die-casting aluminum alloy is 12.0-12.5 wt%, and the high-heat-conductivity high-strength die-casting aluminum alloy in the range has good fluidity, low solidification shrinkage and extremely low casting heat cracking tendency.

In the high-heat-conductivity high-strength die-casting aluminum alloy, the content of iron in the high-heat-conductivity high-strength die-casting aluminum alloy is 0.45-0.55 wt%, and the high-heat-conductivity high-strength die-casting aluminum alloy in the interval range can better avoid die sticking in the die-casting process.

In the high-heat-conductivity and high-strength die-casting aluminum alloy, the content of magnesium in the high-heat-conductivity and high-strength die-casting aluminum alloy is 0.25-0.3 wt%, so that the strength of a casting product can be effectively improved, but excessive magnesium can hinder the heat conductivity.

In the high-heat-conductivity and high-strength die-casting aluminum alloy, the proportion of boron in the high-heat-conductivity and high-strength die-casting aluminum alloy is 0.2-0.3 wt%, the as-cast structure of the alloy is refined, B can be combined with impurity elements such as Ti, V and Cr in the aluminum alloy to form boride precipitates such as TiB2, V2B3 and Cr2B, and the influence of the impurity elements on the heat conductivity of the aluminum alloy is eliminated.

In the high-heat-conductivity high-strength die-casting aluminum alloy, the head of the crystal of the eutectic Si can be made into a fine particle shape by adding strontium and Sr, so that the strength of the alloy is effectively improved, Sr has a very large effect on modification and refinement of the eutectic Si, the refined eutectic silicon is stable in arrangement direction, refraction in a heat conduction and transfer process is reduced, and the heat conductivity coefficient is improved.

The mechanical properties and thermal conductivity measurements of the new high thermal conductivity high strength die cast aluminum alloy are shown in the examples of table 2.

TABLE 2 mechanical Properties and thermal conductivity measurements

It will be appreciated by persons skilled in the art that the embodiments of the invention shown in the foregoing description are by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.