阅读说明：本技术 高强度压铸铝合金及其制备方法 (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：本申请公开高强度压铸铝合金及其制备方法,其中所述高强度压铸铝合金由7.0～8.0重量％的硅、最多0.25重量％的铁,0.55～0.65重量％的镁,3.0～4.0重量％的铜,0.4～0.5重量％的锰,9.0～10.0重量％的锌,0.08～0.15重量％的钛,0.04～0.07重量％的钒,最多0.05重量％的锶,最多0.1重量％的铅,其余为铝组成。(Disclosed are a high-strength die-cast aluminum alloy and a method for producing the same, wherein the high-strength die-cast aluminum alloy is composed of 7.0 to 8.0 wt% of silicon, 0.25 wt% or less of iron, 0.55 to 0.65 wt% of magnesium, 3.0 to 4.0 wt% of copper, 0.4 to 0.5 wt% of manganese, 9.0 to 10.0 wt% of zinc, 0.08 to 0.15 wt% of titanium, 0.04 to 0.07 wt% of vanadium, 0.05 wt% or less of strontium, 0.1 wt% or less of lead, and the balance of aluminum.)

1. The high-strength die-casting aluminum alloy is characterized by comprising the following elements:

7.0 to 8.0 wt.% silicon, up to 0.25 wt.% iron, 0.55 to 0.65 wt.% magnesium, 3.0 to 4.0 wt.% copper, 0.4 to 0.5 wt.% manganese, 9.0 to 10.0 wt.% zinc, 0.08 to 0.15 wt.% titanium, 0.04 to 0.07 wt.% vanadium, up to 0.05 wt.% strontium, up to 0.1 wt.% lead, and the balance aluminum.

2. The high strength die cast aluminum alloy of claim 1, wherein the manganese to iron percentage ratio is 2: 1.

3. The preparation method for preparing the high-strength cast aluminum alloy is characterized by comprising the following steps of:

(1) putting pure aluminum ingots and silicon into smelting equipment for smelting, and controlling the temperature of aluminum liquid to be 710-730 ℃;

(2) adding iron, magnesium, copper, manganese, zinc, titanium, vanadium and lead into the molten aluminum, wherein 7.0-8.0 wt% of silicon, 0.25 wt% of iron at most, 0.55-0.65 wt% of magnesium, 3.0-4.0 wt% of copper, 0.4-0.5 wt% of manganese, 9.0-10.0 wt% of zinc, 0.08-0.15 wt% of titanium, 0.04-0.07 wt% of vanadium, 0.1 wt% of lead at most and the balance of aluminum are added;

(3) when the temperature of the aluminum liquid is reduced to 720-730 ℃, pressing a special rare earth refining agent for the aluminum alloy into the aluminum alloy for refining; and

(4) and (2) modifying the aluminum liquid at the temperature of 710-720 ℃, pressing an Al-Sr modifier into the aluminum liquid by using a bell jar to modify, and introducing nitrogen into the aluminum liquid to degas for a preset time, wherein the weight percentage of strontium is at most 0.05.

4. The method for preparing a high-strength cast aluminum alloy according to claim 3, 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.

5. The method for preparing a high-strength cast aluminum alloy according to claim 4, wherein the method is performed for 5 to 10 minutes.

6. The method of making a high strength cast aluminum alloy article of claim 4, wherein the nitrogen is applied for a period of at least 10 minutes.

7. The method for preparing a high strength aluminum casting alloy according to claim 4, wherein Cu element is added as Al-Cu master alloy, Si element is added as elemental 3303 silicon, Mg element is added as pure Mg ingot, Mn element is added as Al-Mn master alloy, Ti element is added as Al-Ti master alloy, Zn element is added as pure Zn ingot, V element is added as V master alloy, and Sr element is added as Sr master alloy to the molten aluminum.

8. The method of making a high strength cast aluminum alloy article of claim 4, wherein the aluminum, silicon, manganese, and iron form a quaternary AlSiMnFe phase during the making.

9. The method of making a high strength cast aluminum alloy article of claim 8, wherein the quaternary AlSiMnFe phase has regular polygonal shaped grains.

Technical Field

The invention relates to the field of die-casting aluminum alloy, in particular to 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 strength die cast aluminum alloy and a method for producing the same, wherein the high strength die cast aluminum alloy has a tensile yield limit rp0.2 >250MPa and at the same time an elongation at break a > 2.0%, a tensile strength Rm >360MPa, and a brinell hardness >100HB in an as-cast state, which can be used for manufacturing communication products having a complicated structure, an uneven rear wall, and a thin overall wall thickness.

It is another object of the present invention to provide a high strength die casting aluminum alloy having good structural uniformity, especially a uniform microstructure with controllable composition, to ensure good castability, mold filling property and good solidification property of the high strength die casting aluminum alloy, and a method for preparing the same.

To achieve at least one of the above objects of the present invention, the present invention provides a high-strength die-cast aluminum alloy consisting of:

7.0 to 8.0 wt.% silicon, up to 0.25 wt.% iron, 0.55 to 0.65 wt.% magnesium, 3.0 to 4.0 wt.% copper, 0.4 to 0.5 wt.% manganese, 9.0 to 10.0 wt.% zinc, 0.08 to 0.15 wt.% titanium, 0.04 to 0.07 wt.% vanadium, up to 0.05 wt.% strontium, up to 0.1 wt.% lead, and the balance aluminum.

According to an embodiment of the invention, the percentage ratio of manganese to iron is 2: 1.

To achieve at least one of the above objects, the present invention provides a method for producing a high-strength cast aluminum alloy, comprising the steps of:

(1) putting pure aluminum ingots and silicon into smelting equipment for smelting, and controlling the temperature of aluminum liquid to be 710-730 ℃;

(2) adding iron, magnesium, copper, manganese, zinc, titanium, vanadium, strontium and lead into the molten aluminum, wherein 7.0-8.0 wt% of silicon, 0.25 wt% of iron at most, 0.55-0.65 wt% of magnesium, 3.0-4.0 wt% of copper, 0.4-0.5 wt% of manganese, 9.0-10.0 wt% of zinc, 0.08-0.15 wt% of titanium, 0.04-0.07 wt% of vanadium, 0.05 wt% of strontium at most, 0.1 wt% of lead at most and the balance of aluminum;

(3) when the temperature of the aluminum liquid is reduced to 720-730 ℃, pressing a special rare earth refining agent for the aluminum alloy into the aluminum alloy for refining; and

(4) and (2) modifying the aluminum liquid at the temperature of 710-720 ℃, pressing an Al-Sr modifier into the aluminum liquid by using a bell jar to modify, and introducing nitrogen into the aluminum liquid to degas for a preset time, wherein the weight percentage of strontium is at most 0.05.

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 one embodiment of the invention, Cu is added in the form of Al-Cu master alloy, Si is added in the form of simple substance 3303 Si, Mg is added in the form of pure Mg ingot, Mn is added in the form of Al-Mn master alloy, Ti is added in the form of Al-Ti master alloy, Zn is added in the form of pure Zn ingot, V is added in the form of V master alloy, and Sr is added in the form of Sr master alloy to the molten aluminum.

According to one embodiment of the invention, during fabrication, aluminum, silicon, manganese, and iron form a quaternary AlSiMnFe phase.

According to an embodiment of the invention, the quaternary AlSiMnFe phase has regular polygonal particles.

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 present invention, the high strength die-cast aluminum alloy can be used for manufacturing communication products with complex structures, uneven rear walls and thin overall wall thickness.

The high-strength die-cast aluminum alloy includes: 7.0 to 8.0 wt.% silicon, up to 0.25 wt.% iron, 0.55 to 0.65 wt.% magnesium, 3.0 to 4.0 wt.% copper, 0.4 to 0.5 wt.% manganese, 9.0 to 10.0 wt.% zinc, 0.08 to 0.15 wt.% titanium, 0.04 to 0.07 wt.% vanadium, up to 0.05 wt.% strontium, up to 0.1 wt.% lead, and the balance aluminum.

Preferably, the high strength cast aluminum alloy is prepared by the following steps:

(1) preparing materials and cleaning a furnace. Preparing materials according to the proportion of alloy components, cleaning the furnace after the materials are prepared, and adding the alloy elements in the form of pure metals or intermediate alloys. Preferably, Cu element is added in the form of Al-Cu master alloy, Si element is added in the form of simple substance 3303 silicon, Mg element is added in the form of pure Mg ingot, Mn element is added in the form of Al-Mn master alloy, Ti element is added in the form of Al-Ti master alloy, Zn element is added in the form of pure Zn ingot, V element is added in the form of V master alloy, and Sr element is added in the form of Sr 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) when the temperature of the aluminum liquid reaches 720-730 ℃, adding an intermediate alloy into the aluminum liquid; when the temperature of the aluminum liquid reaches 730-740 ℃, adding the dried Al-Cu intermediate alloy, magnesium ingot, zinc ingot, Al-V intermediate alloy and Al-Ti intermediate alloy into the aluminum liquid, heating the aluminum liquid to 740 ℃, and keeping the temperature for 15 minutes to ensure that the added intermediate alloy is completely melted;

(4) refining, specifically, when the temperature of molten aluminum is reduced to 720-730 ℃, pressing a special rare earth refining agent for aluminum alloy into a bell jar for refining, and stirring the bell jar up and down in the refining process until the alloy is fully refined; standing for a preset time to enable the impurities to sufficiently float or sink, and then pulling out the slag; preferably, the mixture is kept still for 5-10 minutes.

(5) Modification and degassing: and (2) modifying the aluminum liquid at the temperature of 710-720 ℃, pressing an Al-Sr modifier 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, pulling out slag after standing, and removing surface oxide skin.

In different examples, the high strength die cast aluminum alloys produced had different properties as shown in table 1 below:

TABLE 1 Properties at steady state of the high strength die cast aluminum alloys worthy of different examples

In the high-strength die-casting aluminum alloy, the content of silicon in the high-strength die-casting aluminum alloy is 7.0-8.0 wt%, and the high-strength die-casting aluminum alloy in the range belongs to hypoeutectic aluminum alloy, has natural timeliness and good fluidity after die casting, and is low in solidification shrinkage and extremely low in casting hot cracking tendency.

In the high-strength die-casting aluminum alloy mentioned above, the content of magnesium in the high-strength die-casting aluminum alloy is 0.55 to 0.65 wt%, and magnesium can enhance the strength of the alloy, because a small amount of magnesium is added to the aluminum-silicon alloy to form Mg₂A Si phase.

On cooling, Mg₂Si dissolved in α solid solution distorts the crystal lattice of α solid solution, strengthening the alloy, and excess Mg is formed beyond 0.7% Mg₂The Si strengthening phase may thus become a brittle phase, resulting in increased brittleness during production of the material.

In the high-strength die-casting aluminum alloy, the zinc accounts for 9.0-10.0 wt% of the high-strength die-casting aluminum alloy, the zinc has high solubility in aluminum, is not easy to decompose in the casting cooling solidification process, and can obtain solid solution strengthening. Zinc is supersaturated and dissolved in the alpha solid solution, and is precipitated and strengthened by dispersion particles in the aging process.

In the above-mentioned high-strength die-cast aluminum alloy, the form of the eutectic silicon can be modified by adding strontium, so that the generation of coarse flaky silicon phases is avoided, and a fine rod-like eutectic silicon structure is formed. The deteriorated eutectic silicon has great influence on the mechanical properties of casting products, and particularly can greatly improve the elongation at break.

In the high-strength die-casting aluminum alloy mentioned above, the combination of vanadium and manganese, by adding at most 0.25 wt% of iron and at most 0.55 wt% of manganese, ensures that the ratio of manganese to iron is 2:1, which can avoid the formation of coarse flaky AlFeSi phase (which has a great influence on the plasticity of the product), and simultaneously, the formed quaternary AlSiMnFe phase has a regular polygonal shape, fine particle size distribution is uniform, and the influence on the plasticity is small. And adding 0.04-0.07 wt% of vanadium to spheroidize polygonal AlSiMnFe phase into a punctiform compound, thereby improving the plasticity of the material.

Compared with the material disclosed in the publication No. CN110735072A, the material is adjusted by using copper and zinc reinforced materials, the solid solution reinforcement of Zn and Al2Cu is mainly reinforced, proper vanadium is added to reduce natural aging time, the content of magnesium is reduced, the brittleness of the material is reduced, and the conditions of hot cracking and demoulding ejection cracking are avoided in the die-casting production process.

The mechanical properties and the natural ageing after 1 month of standing of the new high strength die cast aluminium alloy are shown in the examples of table 2.

TABLE 2 mechanical properties and natural aging after 1 month of storage

The high-strength die-casting aluminum alloy is particularly suitable for manufacturing high-strength parts, particularly high-strength low-toughness mobile phone middle plates required in the market at present.

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.