Rare earth element-free high-performance aluminum alloy for die casting and preparation and die casting methods thereof

Abstract

The invention relates to the technical field of die casting alloys, in particular to a rare earth element-free high-performance aluminum alloy for die casting and a preparation and die casting method thereof. The aluminum alloy comprises the following components in percentage by mass: 7%-10% of silicon, 1%-5% of copper, 8%-18% of zinc, 0.01%-0.8% of iron, 0.01%-0.8% of manganese, 0.01%-0.8% of nickel, 0.01%-0.8% of titanium, 0.01%-0.8% of magnesium, 0.01%-0.8% of chromium and the balance of aluminum and inevitable impurity elements. The high solid solubility of the zinc alloy in the aluminum alloy is utilized, the adding proportion of the zinc element is increased to the level only second to the proportion of the aluminum element, the rapid cooling technology in the die casting process is combined, the alloying degree of the aluminum and the elements such as iron, manganese, chromium, nickel, magnesium and titanium can be effectively controlled, and the yield of the aluminum alloy is improved. And the influence of fluctuation of the content of elements such as iron, manganese, chromium, nickel, magnesium and titanium on the performance of the aluminum alloy die casting is reduced.

Description

Technical Field

[0001] This invention relates to the field of die-casting alloy technology, and in particular to a high-performance aluminum alloy for die casting that does not contain rare earth elements, as well as its preparation and die-casting method. Background Technology

[0002] Aluminum alloys, characterized by low density, high specific strength, high corrosion resistance, and ease of processing, are widely used in new energy vehicles, 3C electronics, and photovoltaic inverters. Currently, the most widely used aluminum alloy material in the die-casting industry is the aluminum-silicon alloy represented by ADC12 alloy. It possesses excellent die-casting and processing properties, and can utilize scrap aluminum as raw material, resulting in lower production costs and suitability for large-scale production. However, with the development of industry applications, the requirements for lightweight, high-strength, high thermal conductivity, and low porosity in die-cast parts are gradually increasing, and conventional aluminum alloy materials cannot meet these performance requirements. Some die-casting alloys incorporate rare earth elements. Although rare earth elements, due to their unique atomic structure (their outer electron configuration easily forms stable compounds with elements such as aluminum and silicon), can achieve multi-dimensional performance improvements in aluminum alloys through "refining grains, purifying grain boundaries, and regulating the second phase."

[0003] Furthermore, due to the uncertainty of the source of recycled alloys, trace elements such as iron, manganese, chromium, nickel, magnesium, and titanium, which constitute less than 1% by mass, may have adverse effects on aluminum alloy materials. These elements can react with aluminum alloys to form multi-phase structures. While trace amounts of multi-phase structures can refine grains and improve the strength and toughness of aluminum alloys, excessive amounts of multi-phase structures can increase the brittleness of aluminum alloys and reduce elongation. This is the fundamental reason why it is difficult to prepare high-performance aluminum alloys using recycled aluminum alloys as the base material.

[0004] Therefore, it is necessary to develop a die-cast aluminum alloy material with better overall performance to meet the demand for high-performance aluminum alloys in industries such as new energy vehicles, 3C electronics, and photovoltaic inverters without increasing alloy costs. Summary of the Invention

[0005] The purpose of this invention is to provide a high-performance aluminum alloy for die casting that does not contain rare earth elements, in order to solve at least one of the above-mentioned technical problems.

[0006] A high-performance aluminum alloy for die casting that does not contain rare earth elements, comprising the following components by mass percentage: 7-10% silicon, 1-5% copper, 8-18% zinc, 0.01-0.8% iron, 0.01-0.8% manganese, 0.01-0.8% nickel, 0.01-0.8% titanium, 0.01-0.8% magnesium, 0.01-0.8% chromium, with the balance being aluminum and unavoidable impurity elements.

[0007] Furthermore, the preparation method of the high-performance aluminum alloy includes the following steps: 1) Using recycled aluminum alloy as raw material, it is melted in a smelting furnace and heated to 720±20 degrees Celsius, and a slag-forming agent is added to remove slag; 2) Take out a small amount of the molten aluminum from step 1), and after solidification, measure the alloy composition. Based on the content of aluminum, silicon, copper, and zinc in the alloy, calculate the weight of aluminum, silicon, copper, and zinc metals that need to be added. 3) Add the calculated aluminum, silicon, copper, and zinc metal materials, adjust the temperature of the alloy aluminum liquid to 680-720 degrees Celsius, add slag-forming agent to remove slag, stir, degas, and remove slag again after 10-20 minutes; 4) After the temperature of the molten aluminum is reduced to 650±10 degrees Celsius, it is poured into aluminum ingots.

[0008] In this embodiment, the slag-forming agent is selected from the crushed granules of porous rocks such as gangue. It has a relatively low melting point and can adsorb impurities in the aluminum melt. The amount added is generally 0.5-1wt%.

[0009] Furthermore, in step 1), the aluminum alloys recycled mainly use aluminum-silicon alloys, selected from one or more of ADC12, AlSi8, and AlSi9Cu3.

[0010] Furthermore, step 1) also includes a pretreatment before the recycled aluminum alloy is placed into the smelting furnace, the pretreatment comprising the following steps: 1) Mechanical cleaning and alkaline or acid washing to remove surface plastics, coatings, oil stains and oxide layers; 2) Low-temperature plasma cleaning: The gas used is air or nitrogen, the power is 100-300w, the time is 2-10 minutes, the temperature is <80℃, and atmospheric pressure jet type or vacuum plasma cleaning is used.

[0011] Setting up a low-temperature plasma purification process before slag removal with slag-forming agents can effectively remove oil, oxide layers, coatings, and micron-sized adsorbed impurities from the surface of aluminum raw materials, as well as metallic inclusions such as Fe / Mn and non-metallic oxides such as Al2O3 inside the aluminum melt. This avoids contaminating the aluminum melt after high-temperature decomposition / oxidation of surface impurities, separates insoluble impurities from the aluminum melt, and forms a complementary system of "surface purification and internal impurity removal" in the pretreatment process of aluminum alloy recycling smelting. This reduces the amount of surface oxide layer entering the aluminum melt, reduces the amount of Al2O3 processed by the slag-forming agent, and allows for the further removal of deep internal impurities from the surface of the aluminum raw materials, thus comprehensively improving the purity of the aluminum alloy from the "surface of the raw materials" to the "inside of the aluminum melt".

[0012] Furthermore, in step 3), the supplemented copper is made from recycled copper-zinc alloy, selected from one or more of H68, H80, and C2600.

[0013] Furthermore, the zinc added in step 3) is a recycled zinc-copper alloy or zinc-aluminum alloy, selected from one or more of the ZAMAK series zinc-copper alloys and ZA series zinc-aluminum alloys.

[0014] Another objective of this invention is to provide a die-casting method for high-performance aluminum alloys that do not contain rare earth elements.

[0015] A die-casting method for a high-performance aluminum alloy that does not contain rare earth elements, the die-casting method comprising the following steps: 1) Molten aluminum alloy, solution temperature 640~689℃; 2) During die casting, a water-cooled mold is used as the die casting mold, and the cooling water temperature is controlled at 30~60℃, with a cooling water flow rate of 100m³ / h. 3 / h, die casting pressure is 150~180MPa, injection speed is 50~80m / s, and vacuum degree of die casting cavity is less than 50mbar.

[0016] The beneficial effects of adopting the technical solution of the present invention are: This invention utilizes the high solid solubility of zinc alloy in aluminum alloy to increase the proportion of zinc to a level second only to aluminum. Combined with the rapid cooling process in die casting, it can effectively control the alloying degree of elements such as iron, manganese, chromium, nickel, magnesium, and titanium with aluminum, and reduce the impact of fluctuations in the content of these elements on the performance of aluminum alloy die castings.

[0017] The aluminum-silicon-copper-zinc alloy material provided by this invention lowers the melting point of the alloy and improves the fluidity of the molten alloy by increasing the proportion of zinc added. Increasing the die-casting pressure and injection speed allows the molten aluminum alloy to quickly fill the mold cavity; high vacuum prevents the formation of pores in the die-casting; rapid cooling significantly increases the solid solubility of zinc in the aluminum alloy, improving the mechanical strength of the alloy. Simultaneously, rapid cooling helps form dense and fine grains on and below the surface of the casting, improving the thermal conductivity of the die-casting. Detailed Implementation

[0018] The following embodiments are provided to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but these embodiments are not intended to limit the scope of protection of the present invention. As used herein, "an embodiment" or "an embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments.

[0019] A high-performance aluminum alloy for die casting that does not contain rare earth elements, comprising the following components by mass percentage: 7-10% silicon, 1-5% copper, 8-18% zinc, 0.01-0.8% iron, 0.01-0.8% manganese, 0.01-0.8% nickel, 0.01-0.8% titanium, 0.01-0.8% magnesium, 0.01-0.8% chromium, with the balance being aluminum and unavoidable impurity elements.

[0020] This invention utilizes the high solid solubility of zinc alloy in aluminum alloy to increase the proportion of zinc to a level second only to aluminum. Combined with the rapid cooling process in die casting, it can effectively control the alloying degree of elements such as iron, manganese, chromium, nickel, magnesium, and titanium with aluminum, and reduce the impact of fluctuations in the content of these elements on the performance of aluminum alloy die castings.

[0021] The die-casting method for high-performance aluminum alloys without rare earth elements in this application includes the following steps: 1) Molten aluminum alloy, solution temperature 640~689℃; 2) During die casting, a water-cooled mold is used as the die casting mold, and the cooling water temperature is controlled at 30~60℃, with a cooling water flow rate of 100m³ / h. 3 / h, die casting pressure is 150~180MPa, injection speed is 50~80m / s, and vacuum degree of die casting cavity is less than 50mbar.

[0022] The following examples illustrate the technical solutions of the present invention using recycled ADC12 alloy as the base alloy. The related technical solutions are mainly used to explain the design concept of the present invention, and the examples are not intended to limit the present invention.

[0023] Example 1 Based on a ton of alloy composition, the main elements by mass percentage are: 7.5% silicon, 3% copper, and 15% zinc; elements such as iron, manganese, chromium, nickel, magnesium, and titanium are controlled within 0.8%. The typical composition of recycled ADC12 alloy is as follows by weight percentage: aluminum - 85%, silicon - 10.5%, copper - 2.4%, iron - 0.8%, manganese - 0.2%, magnesium - 0.2%, zinc - 0.8%, titanium - 0.04%, chromium - 0.4%, nickel - 0.07%, with the balance being unavoidable impurity elements.

[0024] Based on silicon in the recycled ADC12 alloy, the proportions are: 714.3 kg ADC12 alloy, 12.9 kg pure copper ingots, 144.3 kg pure zinc ingots, and 128.5 kg pure aluminum ingots. The aluminum alloy is prepared according to this proportion using the following steps: (1) Mechanical cleaning and alkaline or acid washing to remove surface plastic, coating, oil and oxide layer and then low temperature plasma cleaning: air is used, power is 180w, time is 8 minutes, temperature is 50℃, and atmospheric pressure jet or vacuum plasma cleaning is used. The pretreated recycled aluminum is placed in a smelting furnace to melt and heated to 720±20 degrees Celsius. 0.5wt% gangue granular slag remover is added for slag removal. (2) Take out a small amount of molten aluminum using a graphite crucible. After solidification, measure the alloy composition using an electric spark direct-reading spectrometer. Calculate the weight of aluminum, copper, zinc and other metals that need to be added based on the content of aluminum, copper and zinc in the alloy. (3) Add the calculated aluminum, copper, zinc and other metal materials, adjust the temperature of the alloy aluminum liquid to 680-720 degrees Celsius, add slag remover to remove slag, use an ultrasonic oscillator to stir the aluminum liquid, and use nitrogen or argon to degas the aluminum alloy melt. Remove slag again after 10-20 minutes. (4) After the temperature of the molten aluminum is reduced to 650±10 degrees Celsius, it is cast into aluminum ingots; Example 2 Based on a ton of alloy composition, the main elements by mass percentage are: 8% silicon, 4% copper, and 16% zinc; iron, manganese, chromium, nickel, magnesium, titanium, and other elements are controlled within 0.8%. The typical composition of recycled ADC12 alloy is as follows by weight percentage: aluminum - 85%, silicon - 10.5%, copper - 2.4%, iron - 0.8%, manganese - 0.2%, magnesium - 0.2%, zinc - 0.8%, titanium - 0.04%, chromium - 0.4%, nickel - 0.07%, with the balance being unavoidable impurity elements.

[0025] Based on silicon in the recycled ADC12 alloy, the proportions are: 761.9 kg ADC12 alloy, 21.7 kg pure copper ingots, 153.9 kg pure zinc ingots, and 62.5 kg pure aluminum ingots. The aluminum alloy is prepared according to this proportion using the following steps: (1) Mechanical cleaning and alkaline or acid washing to remove surface plastic, coating, oil and oxide layer and then low temperature plasma cleaning: nitrogen gas is used, power is 200w, time is 8 minutes, temperature is 60℃, and atmospheric pressure jet or vacuum plasma cleaning is used. The pretreated recycled aluminum is placed in a smelting furnace to melt and heated to 720±20 degrees Celsius. 0.8wt% gangue granular slag remover is added for slag removal. (2) Take out a small amount of molten aluminum using a graphite crucible. After solidification, measure the alloy composition using an electric spark direct-reading spectrometer. Calculate the weight of aluminum, copper, zinc and other metals that need to be added based on the content of aluminum, copper and zinc in the alloy. (3) Add the calculated aluminum, copper, zinc and other metal materials, adjust the temperature of the alloy aluminum liquid to 680-720 degrees Celsius, add slag remover to remove slag, use an ultrasonic oscillator to stir the aluminum liquid, and use nitrogen or argon to degas the aluminum alloy melt. Remove slag again after 10-20 minutes. (4) After the temperature of the molten aluminum is reduced to 650±10 degrees Celsius, it is cast into aluminum ingots.

[0026] Example 3 Based on a ton of alloy composition, the main elements by mass percentage are: 8.5% silicon, 4% copper, and 17% zinc; iron, manganese, chromium, nickel, magnesium, titanium, and other elements are controlled within 0.8%. The typical composition of recycled ADC12 alloy is as follows by weight percentage: aluminum - 85%, silicon - 10.5%, copper - 2.4%, iron - 0.8%, manganese - 0.2%, magnesium - 0.2%, zinc - 0.8%, titanium - 0.04%, chromium - 0.4%, nickel - 0.07%, with the balance being unavoidable impurity elements.

[0027] Based on silicon in the recycled ADC12 alloy, the proportions are: 809.5 kg ADC12 alloy, 20.6 kg pure copper ingots, 163.5 kg pure zinc ingots, and 6.5 kg pure aluminum ingots. The aluminum alloy is prepared according to this proportion using the following steps: (1) Mechanical cleaning and alkaline or acid washing to remove surface plastic, coating, oil and oxide layer and then low temperature plasma cleaning: nitrogen gas is used, power is 200w, time is 8 minutes, temperature is 60℃, and atmospheric pressure jet or vacuum plasma cleaning is used. The pretreated recycled aluminum is placed in a smelting furnace to melt and heated to 720±20 degrees Celsius. 0.8wt% gangue granular slag remover is added for slag removal. (2) Take out a small amount of molten aluminum using a graphite crucible. After solidification, measure the alloy composition using an electric spark direct-reading spectrometer. Calculate the weight of aluminum, copper, zinc and other metals that need to be added based on the content of aluminum, copper and zinc in the alloy. (3) Add the calculated aluminum, copper, zinc and other metal materials, adjust the temperature of the alloy aluminum liquid to 680-720 degrees Celsius, add slag remover to remove slag, use an ultrasonic oscillator to stir the aluminum liquid, and use nitrogen or argon to degas the aluminum alloy melt. Remove slag again after 10-20 minutes. (4) After the temperature of the molten aluminum is reduced to 650±10 degrees Celsius, it is cast into aluminum ingots.

[0028] Example 4 Based on a ton of alloy composition, the main elements by mass percentage are: 9% silicon, 3% copper, and 18% zinc; iron, manganese, chromium, nickel, magnesium, titanium, and other elements are controlled within 0.8%. The typical composition of recycled ADC12 alloy is as follows by weight percentage: aluminum - 85%, silicon - 10.5%, copper - 2.4%, iron - 0.8%, manganese - 0.2%, magnesium - 0.2%, zinc - 0.8%, titanium - 0.04%, chromium - 0.4%, nickel - 0.07%, with the balance being unavoidable impurity elements.

[0029] Using aluminum from recycled ADC12 alloy as the calculation basis, the feed ratio is: 812 kg ADC12 alloy, 10.5 kg pure copper ingot, 173.5 kg pure zinc ingot, and 4.7 kg pure silicon. The aluminum alloy is prepared according to this ratio, following these steps: (1) Mechanical cleaning and alkaline or acid washing to remove surface plastic, coating, oil and oxide layer and then low temperature plasma cleaning: nitrogen gas is used, power is 250w, time is 5 minutes, temperature is 60℃, and atmospheric pressure jet or vacuum plasma cleaning is used. The pretreated recycled aluminum is placed in a smelting furnace to melt and heated to 720±20 degrees Celsius. 1 wt% gangue granular slag remover is added to remove slag. (2) Take out a small amount of molten aluminum using a graphite crucible. After solidification, measure the alloy composition using an electric spark direct-reading spectrometer. Calculate the weight of aluminum, copper, zinc and other metals that need to be added based on the content of aluminum, copper and zinc in the alloy. (3) Add the calculated aluminum, copper, zinc and other metal materials, adjust the temperature of the alloy aluminum liquid to 680-720 degrees Celsius, add slag remover to remove slag, use an ultrasonic oscillator to stir the aluminum liquid, and use nitrogen or argon to degas the aluminum alloy melt. Remove slag again after 10-20 minutes. (4) After the temperature of the molten aluminum is reduced to 650±10 degrees Celsius, it is cast into aluminum ingots.

[0030] The die-casting method for high-performance aluminum alloys for die casting that do not contain rare earth elements in Examples 1-4 includes the following steps: 1) Molten aluminum alloy, solution temperature 660±20℃; 2) During die casting, a water-cooled mold is used as the die casting mold, and the cooling water temperature is controlled at 40±10℃, with a cooling water flow rate of 100m³ / h. 3 The die-casting pressure is 160 MPa, the injection speed is 60 m / s, and the vacuum degree of the die-casting mold cavity is 50 mbar.

[0031] The alloys of Examples 1-4 were melted and prepared into standard sheet and rod specimens using the aforementioned die-casting process. Performance tests were then conducted using methods specified in GBT228-2010, GBT22315-08, GBT229-2007, GBT1943-2007, and GBT12966-2008.

[0032] The test results are shown in Table 1. Table 1 As can be seen from Table 1, the aluminum alloy material prepared according to the present invention can be used to prepare ultra-thin die castings under the improved die casting process conditions, and has excellent mechanical properties and good thermal conductivity. Its comprehensive performance is better than that of the traditional ADC12 alloy.

[0033] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A high-performance aluminum alloy for die casting that does not contain rare earth elements, characterized in that: It contains the following components by weight percentage: 7-10% silicon, 1-5% copper, 8-18% zinc, 0.01-0.8% iron, 0.01-0.8% manganese, 0.01-0.8% nickel, 0.01-0.8% titanium, 0.01-0.8% magnesium, 0.01-0.8% chromium, with the balance being aluminum and unavoidable impurity elements.

2. The method for preparing a high-performance aluminum alloy for die casting without rare earth elements according to claim 1, characterized in that: The preparation method of the high-performance aluminum alloy includes the following steps: 1) Using recycled aluminum alloy as raw material, it is melted in a smelting furnace and heated to 720±20 degrees Celsius, and a slag-forming agent is added to remove slag; 2) Take out a small amount of the molten aluminum from step 1), and after solidification, measure the alloy composition. Based on the content of aluminum, silicon, copper, and zinc in the alloy, calculate the weight of aluminum, silicon, copper, and zinc metals that need to be added. 3) Add the calculated aluminum, silicon, copper, and zinc metal materials, adjust the temperature of the alloy aluminum liquid to 680-720 degrees Celsius, add slag-forming agent to remove slag, stir, degas, and remove slag again after 10-20 minutes; 4) After the temperature of the molten aluminum is reduced to 650±10 degrees Celsius, it is poured into aluminum ingots.

3. The method for preparing a high-performance aluminum alloy for die casting without rare earth elements according to claim 2, characterized in that: In step 1), the aluminum alloys recycled mainly use aluminum-silicon alloys, selected from one or more of ADC12, AlSi8, and AlSi9Cu3.

4. The method for preparing a high-performance aluminum alloy for die casting without rare earth elements according to claim 2, characterized in that, Step 1) also includes a pretreatment before the recycled aluminum alloy is placed into the smelting furnace, the pretreatment including the following steps: 1) Mechanical cleaning and alkaline or acid washing to remove surface plastics, coatings, oil stains and oxide layers; 2) Low-temperature plasma cleaning: The gas used is air or nitrogen, the power is 100-300w, the time is 2-10 minutes, the temperature is <80℃, and atmospheric pressure jet type or vacuum plasma cleaning is used.

5. The method for preparing a high-performance aluminum alloy for die casting without rare earth elements according to claim 2, characterized in that: In step 3), the copper supplement is made from recycled copper-zinc alloy, selected from one or more of H68, H80, and C2600.

6. The method for preparing a high-performance aluminum alloy for die casting without rare earth elements according to claim 2, characterized in that: The zinc added in step 3) is recycled zinc-copper alloy or zinc-aluminum alloy, selected from one or more of the ZAMAK series zinc-copper alloys and ZA series zinc-aluminum alloys.

7. The die-casting method for high-performance aluminum alloys for die casting that do not contain rare earth elements, as described in any one of claims 1-6, characterized in that, The die-casting method includes the following steps: 1) Molten aluminum alloy, solution temperature 640~689℃; 2) During die casting, a water-cooled mold is used as the die casting mold, and the cooling water temperature is controlled at 30~60℃, with a cooling water flow rate of 100m³ / h. 3 / h, die casting pressure is 150~180MPa, injection speed is 50~80m / s, and vacuum degree of die casting cavity is less than 50mbar.

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