As-cast high-toughness aluminum alloy and composite refining modification treatment process thereof

Abstract

The invention belongs to the technical field of metal materials, and particularly relates to an as-cast high-strength and high-toughness aluminum alloy and a composite refining modification treatment process thereof.The as-cast high-strength and high-toughness aluminum alloy is prepared from, by mass, 9.6%-12.6% of Si, 0.5%-1.5% of Fe, 1.5%-4% of Cu, 0.25%-0.75% of Mn, smaller than or equal to 1% of Ce and the balance Al, according to the as-cast high-strength-and-toughness aluminum alloy, by increasing the content of silicon, iron, copper and manganese, second strengthening phases such as eutectic silicon, MnFeSi and CeCuSi are formed, the mechanical property of the aluminum alloy is jointly improved under composite refining modification treatment, and the finally obtained aluminum alloy has the excellent mechanical property.

Description

Technical Field

[0001] The invention belongs to the technical field of metal materials, and in particular relates to a cast high-strength and toughness aluminum alloy and a composite refinement and modification treatment process thereof. Background Art

[0002] Die-cast aluminum alloys have the properties of high strength, corrosion resistance, good electrical and thermal conductivity, and are widely used in the fields of automobiles, communications electronics, aerospace, high-speed rail, medicine, and chemicals. Among them, die-cast Al-Si-Cu alloy aluminum alloys have excellent fluidity and filling properties, and are particularly suitable for the production of complex shapes and thin-walled products. Due to their low melting temperature and high fluidity, the molten aluminum alloy can be quickly injected into the mold through the die-casting process, and cooled and solidified in a relatively short time. At the same time, Al-Si-Cu alloy aluminum alloys also have excellent mechanical properties, with high tensile strength and yield strength, and certain toughness and hardness, which can meet various engineering requirements.

[0003] However, the second phase is more likely to exist in the casting structure of Al-Si-Cu aluminum alloys, especially when the Si content exceeds its eutectic point of 12.6%. A large amount of disorderly distributed lamellar eutectic silicon and coarse lath-shaped or serrated primary silicon are likely to appear, which can easily lead to the splitting of the alloy matrix and damage the mechanical properties of the casting, especially the elongation, which in turn leads to the comprehensive mechanical properties of Al-Si-Cu aluminum alloy castings often failing to meet the needs of actual production.

[0004] To this end, the Chinese patent with the announcement number CN110079712B discloses a cast high-toughness die-cast aluminum silicon alloy and its preparation method and application, wherein the mass percentage of each element of the cast high-toughness die-cast aluminum silicon alloy is: 8% to 11% Si, 0.4% to 0.8% Mn, 0.1% to 0.4% V, 0.1% to 0.4% Zr, 0.01% to 0.04% Sr, ≤0.2% Fe, ≤0.1% unavoidable inclusions, and the balance is Al. The die-cast aluminum silicon alloy requires a low Fe content (≤0.2%) in the composition, but die-casting practical experience shows that a low Fe content is prone to cause die-casting parts to stick to the mold, thereby affecting the processing effect.

[0005] In addition, the Chinese patent with announcement number CN115976356B discloses a cast high-strength and high-toughness die-cast aluminum-silicon alloy and a preparation method, wherein the die-cast aluminum-silicon alloy used comprises Si: 8.0%-10%, Mg: 0.25%-0.45%, Cu: 0.6%-2.0%, Mn: 0.15%-0.3%, Fe: 0.4%-0.7%, Sr: 0.005%-0.015%, Zn≤0.5%, Ni≤0.3%, Ti≤0.1%, Cr≤0.1%, B≤0.002%, other impurities totaling <0.3%, and the balance being aluminum. The Fe content of the material is selected to be in the range of 0.4%-0.7%, which avoids the die-casting sticking caused by too low Fe content, but the Si content is in the range of 8.0%-10%, which is not conducive to exerting the strengthening effect of eutectic silicon.

[0006] Therefore, how to regulate the microstructure of aluminum alloy (especially the second phase) and give full play to the strengthening effect of the second phase to produce a cast high-strength and tough aluminum alloy with excellent comprehensive mechanical properties through ordinary casting production conditions is a technical problem that technical personnel in this field need to solve. Summary of the invention

[0007] The purpose of the present invention is to provide a cast high-strength and toughness aluminum alloy with excellent comprehensive mechanical properties and a composite refinement and modification process thereof in order to solve the technical problem that the comprehensive mechanical properties of the current Al-Si-Cu series aluminum alloy castings cannot meet the production requirements.

[0008] In view of this, the present invention provides a composite refinement and modification process for a cast high-strength and toughness aluminum alloy. The cast high-strength and toughness aluminum alloy comprises, by mass percentage, Si: 9.6%-12.6%, Fe: 0.5%-1.5%, Cu: 1.5%-4%, Mn: 0.25%-0.75%, Ce: ≤1%, and the balance Al.

[0009] Furthermore, the cast high-strength and toughness aluminum alloy includes, by mass percentage, Si: 9.6%-12.6%, Fe: 0.5%-1.5%, Cu: 1.5%-4%, Mn: 0.25%-0.75%, Ce: ≤1%, Mg: 0.2%-0.4%, Zn≤1%, Ti≤0.1%, Ni≤0.1%, unavoidable impurities not exceeding 0.3%, and the balance Al.

[0010] Furthermore, the cast high-strength and toughness aluminum alloy adopts ADC12 aluminum alloy ingot to obtain molten aluminum by aluminum liquid regeneration smelting, and then adds intermediate alloy to the molten aluminum liquid for composite refinement and modification treatment to generate aluminum alloy, and the intermediate alloy includes Al-5Ti-1B intermediate alloy and Al-10Ce.

[0011] Furthermore, the composite refinement and modification process of the aluminum alloy includes: Step 1, melting: adding ADC12 alloy raw material into a melting furnace for melting to obtain aluminum liquid, and then performing a heat preservation process; Step 2, initial feeding: after the first heat preservation is completed, Al-5Ti-1B master alloy and Al-10Ce master alloy are pressed into the aluminum liquid, and after the master alloy is melted, a second heat preservation is performed; Step 3, casting: scooping the melt in step 2 and casting it into an aluminum alloy ingot, and analyzing the chemical composition of the aluminum alloy ingot; Step 4, adding materials again: after the second heat preservation is completed, according to the chemical composition of the aluminum alloy ingot obtained in step 3, adding a master alloy raw material to the melt in step 2 to adjust the chemical composition of the melt, and after the raw material is melted, heat preservation is performed three times, wherein the master alloy raw material is selected from one or more of aluminum silicon, aluminum iron, aluminum copper, and aluminum manganese master alloy; Step 5, adding a refining agent: pressing the refining agent into the melt of step 4, and obtaining an aluminum alloy melt after standing; Step 6, degassing: degassing the aluminum alloy melt in step 5; Step 7, purification casting treatment: after removing the oxide slag from the aluminum alloy melt, the aluminum alloy melt is cast into a mold to finally obtain an aluminum alloy casting; Step 8: Composition analysis: Sampling and sample preparation are performed on the aluminum alloy casting prepared in step 7, and composition inspection is performed to ensure that the contents of Si, Fe, Cu, and Mn elements in the aluminum alloy are qualified.

[0012] Furthermore, in the step 2, the addition amount of the Al-5Ti-1B master alloy is 0.5-0.75wt% of the weight of the aluminum liquid, and the addition amount of the Al-10Ce master alloy is 5-7.5wt% of the weight of the aluminum liquid.

[0013] Furthermore, in step 2, the Al-5Ti-1B master alloy and the Al-10Ce master alloy are wrapped with aluminum foil and then pressed into the aluminum liquid.

[0014] Furthermore, in step five, the refining agent is selected from one or more of C2Cl6, NaCl, and KCl.

[0015] Furthermore, in step five, the refining agent wrapped in aluminum foil in advance is pressed into the melt using a bell jar, and the bell jar is rotated in the melt in the same direction, and then allowed to stand for 5 to 10 minutes.

[0016] Furthermore, in step six, the gas used is argon, and the degassing time is 5 to 10 minutes.

[0017] A cast high-strength and toughness aluminum alloy is prepared by adopting the above-mentioned composite refinement and modification process.

[0018] The beneficial effects of the present invention are: 1. In the present invention, by increasing the contents of silicon Si, iron Fe, copper Cu, and manganese Mn, second phase strengthening phases such as eutectic silicon, MnFeSi, CeCuSi, etc. can be formed, and the mechanical properties of the aluminum alloy can be jointly improved under the composite refinement and modification treatment.

[0019] 2. In the present invention, Al-5Ti-1B master alloy and Al-10Ce master alloy are used for composite refinement and modification, which can refine the grain size and improve the mechanical properties of the aluminum alloy.

[0020] 3. In the present invention, by using Al-5Ti-1B master alloy and Al-10Ce master alloy for composite refining and modification treatment, the formed CeCuSi precipitate phase tends to grow on the surface of Si-rich phases such as MnFeSi to inhibit the growth of the needle-like phase and effectively alleviate the effect of the needle-like second phase on the matrix splitting.

[0021] 4. In the present invention, the solid solution of Ti element in the CeCuSi phase can reduce the difference in crystal plane spacing between the CeCuSi precipitated phase and Si-rich phases such as MnFeSi, making the interface bonding stronger, and ultimately enhancing the modification effect through synergistic effect, thereby better exerting the strengthening effect of eutectic silicon. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0023] Figure 1 The XRD analysis spectrum of the aluminum alloy casting prepared by the present invention; Figure 2 The dark field phase morphology and EDS-mapping analysis diagram of the MnFeSi phase / CeCuSi phase interface of the aluminum alloy casting prepared by the present invention; Figure 3 This is a high-resolution analysis diagram of the MnFeSi phase / CeCuSi phase interface of the aluminum alloy casting prepared by the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments in the present application belong to the scope of protection of this application.

[0025] In the description of the present application, it should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. For ease of description, the techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0026] It should be noted that, in the present application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises one..." does not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be noted that the scope of the method and device in the embodiment of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.

[0027] A composite refinement and modification process for a cast high-strength and toughness aluminum alloy. The cast high-strength and toughness aluminum alloy comprises, by mass percentage, Si: 9.6%-12.6%, Fe: 0.5%-1.5%, Cu: 1.5%-4%, Mn: 0.25%-0.75%, Ce: ≤1%, and the balance Al.

[0028] Preferably, the cast high-strength and toughness aluminum alloy comprises, by mass percentage: Si: 9.6%-12.6%, Fe: 0.5%-1.5%, Cu: 1.5%-4%, Mn: 0.25%-0.75%, Ce: ≤1%, Mg: 0.2%-0.4%, Zn≤1%, Ti≤0.1%, Ni≤0.1%, unavoidable impurities not exceeding 0.3%, and the balance Al.

[0029] More preferably, the cast high-strength and toughness aluminum alloy includes, by mass percentage, Si: 11.1%-12.6%, Fe: 0.8%-1.5%, Cu: 2.5%-4%, Mn: 0.25%-0.75%, Ce: ≤0.2%-0.4%, Mg: 0.2%-0.4%, Zn≤1%, Ti≤0.1%, Ni≤0.1%, no more than 0.3% of unavoidable impurities, and the balance Al.

[0030] Furthermore, the cast high-strength and toughness aluminum alloy adopts ADC12 aluminum alloy ingot to obtain molten aluminum by aluminum liquid regeneration smelting, and then adds intermediate alloy to the molten aluminum liquid for composite refinement and modification treatment to generate aluminum alloy, and the intermediate alloy includes Al-5Ti-1B intermediate alloy and Al-10Ce.

[0031] Furthermore, the composite refinement and modification process of the aluminum alloy includes: Step 1, melting: adding ADC12 alloy raw material into a melting furnace for melting to obtain aluminum liquid, and then performing a heat preservation process; Step 2, initial feeding: after the first heat preservation is completed, Al-5Ti-1B master alloy and Al-10Ce master alloy are pressed into the aluminum liquid, and after the master alloy is melted, a second heat preservation is performed; Step 3, casting: scooping the melt in step 2 and casting it into an aluminum alloy ingot, and analyzing the chemical composition of the aluminum alloy ingot; Step 4, adding materials again: after the second heat preservation is completed, according to the chemical composition of the aluminum alloy ingot obtained in step 3, adding a master alloy raw material to the melt in step 2 to adjust the chemical composition of the melt, and after the raw material is melted, heat preservation is performed three times, wherein the master alloy raw material is selected from one or more of aluminum silicon, aluminum iron, aluminum copper, and aluminum manganese master alloy; Step 5, adding a refining agent: pressing the refining agent into the melt of step 4, and obtaining an aluminum alloy melt after standing; Step 6, degassing: degassing the aluminum alloy melt in step 5; Step 7, purification casting treatment: after removing the oxide slag from the aluminum alloy melt, the aluminum alloy melt is cast into a mold to finally obtain an aluminum alloy casting; Step 8: Composition analysis: Sampling and sample preparation are performed on the aluminum alloy casting prepared in step 7, and composition inspection is performed to ensure that the contents of Si, Fe, Cu, and Mn elements in the aluminum alloy are qualified.

[0032] As some examples of the present invention, in step one, the ADC12 alloy raw material can be added into a graphite crucible in the melting zone of a resistance furnace for melting to obtain aluminum liquid, the melting temperature of which is 650-700°C, followed by a heat preservation process, the heat preservation time of which is 15-30 minutes.

[0033] Preferably, in the step 2, after the first insulation, the Al-5Ti-1B master alloy with a weight of 0.5-0.75wt% of the weight of the aluminum liquid and the Al-10Ce master alloy with a weight of 5-7.5wt% of the weight of the aluminum liquid are pressed into the aluminum liquid, and circular stirring is performed along half of the radius of the crucible, and the stirring speed is at least 3 circles / minute to ensure that the master alloy and the aluminum liquid are evenly mixed. After the master alloy is melted, a second insulation is performed in the resistance furnace, and the second insulation time is 30-60 minutes.

[0034] Preferably, in step 2, the Al-5Ti-1B master alloy and the Al-10Ce master alloy are wrapped with aluminum foil and then pressed into the aluminum liquid.

[0035] As some examples of the present invention, in step three, a direct reading spectrometer may be used to analyze the chemical composition of the aluminum alloy ingot.

[0036] Preferably, in step 4, the three insulation times are 15 to 30 minutes.

[0037] Furthermore, the amounts of aluminum silicon, aluminum iron, aluminum copper, and aluminum manganese added in step four are detected through step eight as follows: the mass fraction of silicon (Si) in the aluminum alloy casting is 9.6-12.6%, the mass fraction of iron (Fe) is 0.5-1.5%, the mass fraction of copper (Cu) is 1.5-4%, and the mass fraction of manganese (Mn) is 0.25-0.75%.

[0038] As some examples of the present invention, in step five, a bell jar is used to press the wrapped refining agent into the melt of step four at a distance of about 100 mm from the bottom of the crucible, and the bell jar is rotated in the melt in the same direction, and then allowed to stand for 5 to 10 minutes to obtain an aluminum alloy melt.

[0039] As some examples of the present invention, in step five, the refining agent is selected from one or more of C2Cl6, NaCl, and KCl.

[0040] Preferably, in step six, the gas used is argon, and the degassing time is 5 to 10 minutes.

[0041] As some examples of the present invention, in step seven, a slag removal spoon can be used to filter the oxide slag on the surface of the aluminum alloy melt. During the casting process, a filter net is also required to filter and purify the aluminum alloy melt to remove metal inclusions in the alloy.

[0042] As some examples of the present invention, in step eight, the aluminum alloy casting prepared in step seven can be sampled, sampled and subjected to spectral chemical composition inspection to ensure that the silicon (Si), iron (Fe), copper (Cu) and manganese (Mn) in the aluminum alloy are qualified.

[0043] Furthermore, the composite refinement and modification process of the as-cast high-strength and toughness aluminum alloy also includes: Step nine, microstructure analysis: sampling and sample preparation of the aluminum alloy casting prepared in step seven, and performing microstructure analysis and dendrite spacing statistics; Step 10: Mechanical analysis: Sampling and sample preparation are performed on the aluminum alloy castings prepared in step 7, and mechanical testing is performed.

[0044] The following is an example of the as-cast high-strength and toughness aluminum alloy and the composite refinement and modification process of the present invention. Example 1 A composite refinement and modification process for a cast high-strength and tough aluminum alloy comprises the following steps: Step 1, melting: adding ADC12 alloy raw material into a graphite crucible in the melting zone of a resistance furnace to melt to obtain aluminum liquid, the melting temperature is 700°C, and then keeping the temperature for 15 minutes; Step 2, initial charging: After the aluminum liquid is kept warm in step 1, press 0.75wt% of the weight of the aluminum liquid into the aluminum liquid, and stir the aluminum liquid in a circle at half the radius of the crucible at a speed of 3 circles / minute to ensure that the melt is evenly mixed. After the master alloy is melted, keep it warm in the resistance furnace for 60 minutes; Step 3, casting: scoop the melt in step 2 and cast it into a round aluminum ingot with an end diameter of 20 mm, and use a direct reading spectrometer to analyze the chemical composition of the aluminum ingot; Step 4, adding materials again: after the heat preservation of the melt in step 2 is completed, according to the chemical composition of the aluminum ingot in the furnace, add appropriate amounts of aluminum silicon, aluminum iron, aluminum copper, and aluminum manganese master alloy raw materials to the melt in step 2, and keep the raw materials warm for 15 minutes after they are melted. The added amounts make the mass fractions of silicon, iron, copper, and manganese in the final aluminum alloy castings to be silicon (Si) 9.6-12.6%, iron (Fe) 0.5-1.5%, copper (Cu) 1.5-4%, and manganese (Mn) 0.25-0.75%, respectively, which is qualified; Step 5, adding a refining agent: using a bell jar, press the wrapped refining agent C2Cl6 into the melt of step 4 at a distance of 100 mm from the bottom of the crucible, and at the same time rotate the bell jar in the melt in the same direction, and then let it stand for 5 minutes to obtain an aluminum alloy melt; Step 6, degassing: degassing the aluminum alloy melt in step 5; Step 7, purification casting treatment: use a slag removal spoon to filter the oxide slag on the surface of the aluminum alloy melt. During the casting process, a filter net is also used to filter and purify the aluminum alloy melt to remove metal inclusions in the alloy. After removing impurities, the aluminum alloy melt is cast into a mold to finally obtain an aluminum alloy casting; Step 8, component analysis: the aluminum alloy casting prepared in step 7 is sampled and sampled and subjected to spectral chemical composition inspection, so that the final mass fractions are respectively 9.6-12.6% silicon (Si), 0.5-1.5% iron (Fe), 1.5-4% copper (Cu); 0.25-0.75% manganese (Mn). The alloy component detection results of Example 1 are shown in Table 1. In this embodiment, the iron content is 0.89%, which is higher than the iron content in Chinese patent CN110079712B and Chinese patent CN115976356B, which is beneficial to reduce the sticking of the die casting; Step 9, microstructure analysis: the aluminum alloy casting prepared in step 7 is sampled and subjected to microstructure analysis and dendrite spacing statistics. The results are shown in Table 2. Step 10, mechanical analysis: The aluminum alloy casting prepared in step 7 is sampled and subjected to mechanical testing. The results are shown in Table 3. The tensile strength under gravity casting conditions can reach a similar level under die casting conditions (see Chinese patent CN110079712B and Chinese patent CN115976356B).

[0045] In this embodiment, in step 5, the purpose of pressing the refining agent into the crucible 100 mm from the bottom is that the refining agent is relatively light and needs to be pressed into the bottom of the aluminum alloy, and will gradually float up during the stirring process, so most of the aluminum liquid can be processed at the bottom, but at the same time it will not scratch the bottom of the crucible. Similarly, the use of a bell jar to wrap the refining agent is also to slow down the floating of the refining agent. In addition, rotating the bell jar in the melt in the same direction can prevent air from being stirred into the aluminum liquid, avoiding oxidation and air inhalation of the aluminum alloy melt.

[0046] In this embodiment, since the aluminum alloy will absorb air during the smelting process, impurities on the surface of the raw materials will also bring in some water vapor, so the porosity defects in the aluminum alloy can be reduced through degassing treatment.

[0047] Example 2 A composite refinement and modification process for a cast high-strength and tough aluminum alloy comprises the following steps: Step 1, melting: adding ADC12 alloy raw material into a graphite crucible in the melting zone of a resistance furnace to melt to obtain aluminum liquid, the melting temperature is 700°C, and then keeping the temperature for 30 minutes; Step 2, initial feeding: After the aluminum liquid is kept warm in step 1, press 0.5wt.% of the weight of the aluminum liquid into the aluminum liquid, and stir the aluminum liquid in a circle at half the radius of the crucible at a speed of 5 turns / minute to ensure that the melt is evenly mixed. After the master alloy is melted, keep it warm in the resistance furnace for 60 minutes; Step 3, casting: scoop the melt in step 2 and cast it into a round aluminum ingot with an end diameter of 20 mm, and use a direct reading spectrometer to analyze the chemical composition of the aluminum ingot; Step 4, adding materials again: after the heat preservation of the melt in step 2 is completed, according to the chemical composition of the aluminum ingot in the furnace, add appropriate amounts of aluminum silicon, aluminum iron, aluminum copper, and aluminum manganese master alloy raw materials to the melt in step 2, and keep the raw materials warm for 30 minutes after they are melted. The added amounts make the mass fractions of silicon, iron, copper, and manganese in the final aluminum alloy castings to be 9.6-12.6% for silicon (Si), 0.5-1.5% for iron (Fe), 1.5-4% for copper (Cu), and 0.25-0.75% for manganese (Mn), respectively, to be qualified; Step 5, adding a refining agent: using a bell jar, press the wrapped refining agent C2Cl6 into the melt of step 4 at a distance of 100 mm from the bottom of the crucible, and at the same time rotate the bell jar in the melt in the same direction, and then let it stand for 5 minutes to obtain an aluminum alloy melt; Step 6, degassing: degassing the aluminum alloy melt in step 5; Step 7, purification casting treatment: use a slag removal spoon to filter the oxide slag on the surface of the aluminum alloy melt. During the casting process, a filter net is also used to filter and purify the aluminum alloy melt to remove metal inclusions in the alloy. After removing impurities, the aluminum alloy melt is cast into a mold to finally obtain an aluminum alloy casting; Step 8, component analysis: The aluminum alloy casting prepared in step 7 is sampled and sampled and subjected to spectrochemical composition inspection, so that the final mass fractions are respectively 9.6-12.6% silicon (Si), 0.5-1.5% iron (Fe), 1.5-4% copper (Cu); 0.25-0.75% manganese (Mn). The alloy component test results of Example 2 are shown in Table 1, see Table 1; Step 9, microstructure analysis: the aluminum alloy casting prepared in step 7 is sampled and subjected to microstructure analysis and dendrite spacing statistics. The results are shown in Table 2. Step 10, mechanical analysis: The aluminum alloy casting prepared in step 7 is sampled and subjected to mechanical testing. The results are shown in Table 3.

[0048] Example 3 A composite refinement and modification process for a cast high-strength and tough aluminum alloy comprises the following steps: Step 1, melting: adding ADC12 alloy raw material into a graphite crucible in the melting zone of a resistance furnace to melt to obtain aluminum liquid, the melting temperature is 700°C, and then keeping the temperature for 15 minutes; Step 2, initial charging: After the aluminum liquid is kept warm in step 1, press 0.75% of the weight of the aluminum liquid to the Al-5Ti-1B master alloy and 5% of the weight of the aluminum liquid to the Al-10Ce master alloy, and stir the circumference along the half radius of the crucible at a speed of 3 circles / minute to ensure that the melt is evenly mixed. After the master alloy is melted, keep it warm in the resistance furnace for 30 minutes; Step 3, casting: scoop the melt in step 2 and cast it into a round aluminum ingot with an end diameter of 20 mm, and use a direct reading spectrometer to analyze the chemical composition of the aluminum ingot; Step 4, adding materials again: after the heat preservation of the melt in step 2 is completed, according to the chemical composition of the aluminum ingot in the furnace, add appropriate amounts of aluminum silicon, aluminum iron, aluminum copper, and aluminum manganese master alloy raw materials to the melt in step 2, and keep the raw materials warm for 15 minutes after they are melted. The added amounts make the mass fractions of silicon, iron, copper, and manganese in the final aluminum alloy castings to be silicon (Si) 9.6-12.6%, iron (Fe) 0.5-1.5%, copper (Cu) 1.5-4%, and manganese (Mn) 0.25-0.75%, respectively, which is qualified; Step 5, adding a refining agent: using a bell jar, press the wrapped refining agent C2Cl6 into the melt of step 4 at a distance of 100 mm from the bottom of the crucible, and at the same time rotate the bell jar in the melt in the same direction, and then let it stand for 10 minutes to obtain an aluminum alloy melt; Step 6, degassing: degassing the aluminum alloy melt in step 5; Step 7, purification casting treatment: use a slag removal spoon to filter the oxide slag on the surface of the aluminum alloy melt. During the casting process, a filter net is also used to filter and purify the aluminum alloy melt to remove metal inclusions in the alloy. After removing impurities, the aluminum alloy melt is cast into a mold to finally obtain an aluminum alloy casting; Step 8, component analysis: The aluminum alloy casting prepared in step 7 is sampled and sampled and subjected to spectrochemical composition inspection, so that the final mass fractions are respectively silicon (Si) 9.6-12.6%, iron (Fe) 0.5-1.5%, copper (Cu) 1.5-4%; manganese (Mn) 0.25-0.75%. The alloy component detection results of Example 3 are shown in Table 1; Step 9, microstructure analysis: the aluminum alloy casting prepared in step 7 is sampled and subjected to microstructure analysis and dendrite spacing statistics. The results are shown in Table 2. Step 10, mechanical analysis: The aluminum alloy casting prepared in step 7 is sampled and subjected to mechanical testing. The results are shown in Table 3.

[0049] Example 4 A composite refinement and modification process for a cast high-strength and tough aluminum alloy comprises the following steps: Step 1, melting: adding ADC12 alloy raw material into a graphite crucible in the melting zone of a resistance furnace to melt to obtain aluminum liquid, the melting temperature is 700°C, and then keeping the temperature for 30 minutes; Step 2, initial charging: After the aluminum liquid is kept warm in step 1, press 0.6% of the weight of the aluminum liquid to the Al-5Ti-1B master alloy and 6% of the weight of the aluminum liquid to the Al-10Ce master alloy, and stir the circumference along the half radius of the crucible at a speed of 3 circles / minute to ensure that the melt is evenly mixed. After the master alloy is melted, keep it warm in the resistance furnace for 60 minutes; Step 3, casting: scoop the melt in step 2 and cast it into a round aluminum ingot with an end diameter of 20 mm, and use a direct reading spectrometer to analyze the chemical composition of the aluminum ingot; Step 4, adding materials again: after the heat preservation of the melt in step 2 is completed, according to the chemical composition of the aluminum ingot in the furnace, appropriate amounts of aluminum silicon, aluminum iron, aluminum copper, and aluminum manganese intermediate alloy raw materials are added to the melt in step 2, and the raw materials are melted and then kept warm for 30 minutes. The amount of addition is such that the mass fractions of silicon, iron, copper, and manganese in the final aluminum alloy casting are respectively 9.6-12.6% for silicon (Si), 0.5-1.5% for iron (Fe), 1.5-4% for copper (Cu), and 0.25-0.75% for manganese (Mn), which is qualified; Step 5, adding a refining agent: using a bell jar, press the wrapped refining agent C2Cl6 into the melt of step 4 at a distance of 100 mm from the bottom of the crucible, and at the same time rotate the bell jar in the melt in the same direction, and then let it stand for 10 minutes to obtain an aluminum alloy melt; Step 6, degassing: degassing the aluminum alloy melt in step 5; Step 7, purification casting treatment: use a slag removal spoon to filter the oxide slag on the surface of the aluminum alloy melt. During the casting process, a filter net is also used to filter and purify the aluminum alloy melt to remove metal inclusions in the alloy. After removing impurities, the aluminum alloy melt is cast into a mold to finally obtain an aluminum alloy casting; Step 8, component analysis: The aluminum alloy casting prepared in step 7 is sampled and sampled and subjected to spectral chemical composition inspection, so that the final mass fractions are silicon (Si) 9.6-12.6%, iron (Fe) 0.5-1.5%, copper (Cu) 1.5-4%; manganese (Mn) 0.25-0.75%. The alloy composition test results of Example 4 are shown in Table 1; Step 9, microstructure analysis: the aluminum alloy casting prepared in step 7 is sampled and subjected to microstructure analysis and dendrite spacing statistics. The results are shown in Table 2. Step 10, mechanical analysis: The aluminum alloy casting prepared in step 7 is sampled and subjected to mechanical testing. The results are shown in Table 3.

[0050] Table 1 Element composition (wt.%) Table 2 Dendrite spacing (μm) Table 3 Mechanical properties Test example (I) The dark field phase morphology and EDS-mapping analysis of the MnFeSi phase / CeCuSi phase interface of the aluminum alloy casting prepared in Example 1 were as follows: Figure 2 The results shown are: The results show that after the composite refining modification of Al-5Ti-1B master alloy and Al-10Ce master alloy, the formed CeCuSi precipitate phase tends to grow on the surface of Si-rich phases such as MnFeSi to inhibit the growth of the needle-like phase, which can effectively alleviate the effect of the needle-like second phase on the matrix splitting.

[0051] (ii) High-resolution analysis of the MnFeSi phase / CeCuSi phase interface of the aluminum alloy casting prepared in Example 1 yielded the following results: Figure 3 The results shown are: The results show that the composite refining modification treatment of Al-5Ti-1B master alloy and Al-10Ce master alloy reduces the difference in crystal plane spacing between CeCuSi precipitated phase and Si-rich phases such as MnFeSi by solid solution of Ti element in CeCuSi phase, making the interface bonding stronger and enhancing the modification effect.

[0052] (III) XRD pattern analysis was performed on the aluminum alloy casting prepared in Example 1 to obtain the following Figure 1 The results shown are: In the present invention, by increasing the contents of silicon Si, iron Fe, copper Cu, and manganese Mn, second phase strengthening phases such as eutectic silicon, MnFeSi, CeCuSi, etc. can be formed, and the mechanical properties of the aluminum alloy can be jointly improved under the composite refinement and modification treatment.

[0053] The present invention calculates the mismatch degree, density and formation enthalpy of the second phase and the aluminum matrix, selects Al-5Ti-1B master alloy and Al-10Ce master alloy to carry out composite refinement and modification on ADC12 aluminum alloy, and obtains a cast high-strength and tough aluminum alloy die-casting product with a wide composition range of Si, Fe, Mn and Cu. The composition range is larger than the corresponding composition ranges in Chinese patent CN110079712B and Chinese patent CN115976356B, which improves the tolerance of the cast aluminum alloy to the fluctuation of the alloy composition, and makes the tensile strength and elongation of the cast aluminum alloy obtained by ordinary casting production conditions more excellent.

[0054] The embodiments of the present application are described above in conjunction with the accompanying drawings. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.

Claims

1. A composite refinement and modification process for a cast high-strength and tough aluminum alloy, characterized in that: In terms of mass percentage, the cast high-strength and tough aluminum alloy Comprising: Si: 9.6%-12.6%, Fe: 0.5%-1.5%, Cu: 1.5%-4%, Mn: 0.25%-0.75%, Ce: ≤1%, and the balance Al.

2. The composite refinement and modification process of the as-cast high-strength and toughness aluminum alloy according to claim 1, characterized in that: In terms of mass percentage, the cast high-strength and tough aluminum alloy Including: Si: 9.6%-12.6%, Fe: 0.5%-1.5%, Cu: 1.5%-4%, Mn: 0.25%-0.75%, Ce: ≤1%, Mg: 0.2%-0.4%, Zn≤1%, Ti≤0.1%, unavoidable impurities not more than 0.3%, and the balance of Al.

3. The composite refinement and modification process of the as-cast high-strength and toughness aluminum alloy according to claim 1 or 2, characterized in that: The cast high-strength and toughness aluminum alloy adopts ADC12 aluminum alloy ingot to obtain molten aluminum through aluminum liquid regeneration smelting, and then adds intermediate alloy to the molten aluminum liquid for composite refinement and modification treatment to generate aluminum alloy, and the intermediate alloy includes Al-5Ti-1B intermediate alloy and Al-10Ce.

4. The composite refinement and modification process of the as-cast high-strength and toughness aluminum alloy according to claim 3, characterized in that: The composite refinement and modification process of the aluminum alloy comprises: Step 1, melting: adding ADC12 alloy raw material into a melting furnace for melting to obtain aluminum liquid, and then performing a heat preservation process; Step 2, initial feeding: after the first heat preservation is completed, Al-5Ti-1B master alloy and Al-10Ce master alloy are pressed into the aluminum liquid, and after the master alloy is melted, a second heat preservation is performed; Step 3, casting: scooping the melt in step 2 to cast into an aluminum alloy ingot, and analyzing the chemical composition of the aluminum alloy ingot; Step 4, adding materials again: after the second heat preservation is completed, according to the chemical composition of the aluminum alloy ingot obtained in step 3, adding a master alloy raw material to the melt in step 2 to adjust the chemical composition of the melt, and after the raw material is melted, heat preservation is performed three times, wherein the master alloy raw material is selected from one or more of aluminum silicon, aluminum iron, aluminum copper, and aluminum manganese master alloy; Step 5, adding a refining agent: pressing the refining agent into the melt of step 4, and obtaining an aluminum alloy melt after standing; Step 6, degassing: degassing the aluminum alloy melt in step 5; Step 7, purification casting treatment: after removing the oxide slag from the aluminum alloy melt, the aluminum alloy melt is cast into a mold to finally obtain an aluminum alloy casting; Step 8: Composition analysis: Sampling and sample preparation are performed on the aluminum alloy casting prepared in step 7, and composition inspection is performed to ensure that the contents of Si, Fe, Cu, and Mn elements in the aluminum alloy are qualified.

5. The composite refinement and modification process of the as-cast high-strength and toughness aluminum alloy according to claim 4, characterized in that: In the step 2, the addition amount of Al-5Ti-1B master alloy is 0.5-0.75wt% of the weight of the aluminum liquid, and the addition amount of Al-10Ce master alloy is 5-7.5wt% of the weight of the aluminum liquid.

6. The composite refinement and modification process of the as-cast high-strength and toughness aluminum alloy according to claim 5, characterized in that: In step 2, the Al-5Ti-1B master alloy and the Al-10Ce master alloy are wrapped with aluminum foil and then pressed into the aluminum liquid.

7. The composite refinement and modification process of the as-cast high-strength and toughness aluminum alloy according to claim 4, characterized in that: In step five, the refining agent is selected from one or more of C2Cl6, NaCl, and KCl.

8. The composite refinement and modification process of the as-cast high-strength and toughness aluminum alloy according to claim 7, characterized in that: In step five, the refining agent wrapped in aluminum foil in advance is pressed into the melt using a bell jar, and the bell jar is rotated in the melt in the same direction, and then allowed to stand for 5 to 10 minutes.

9. The composite refinement and modification process of the as-cast high-strength and toughness aluminum alloy according to claim 4, characterized in that: The time of the first insulation in step one is 15 to 30 minutes, the time of the second insulation in step two is 30 to 60 minutes, the time of the third insulation in step four is 15 to 30 minutes, and in step six, the gas used is argon, and the degassing time is 5 to 10 minutes.

10. A cast high-strength and tough aluminum alloy, characterized in that: The aluminum alloy is prepared by the composite refinement and modification process described in any one of claims 1 to 9.

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