A heat treatment free high vacuum die casting aluminum alloy and a preparation method thereof

Abstract

The application relates to a heat-treatment-free high-vacuum pressure-casting aluminum alloy and a preparation method thereof, the heat-treatment-free high-vacuum pressure-casting aluminum alloy comprises the following components in percentage by mass: Si 6-8%, Fe 0.5-0.6%, Mn 0.6-0.8%, Mg 0.3-0.4%, Cu 0.6-0.9%, Ti 0.1-0.2%, Sr 0.02-0.05%, and the balance is Al and inevitable impurities. The heat-treatment-free high-vacuum pressure-casting aluminum alloy provided by the application only uses eight alloy elements Al, Si, Fe, Mn, Mg, Cu, Ti and Sr, and through adoption of suitable proportions, the produced aluminum alloy meets the performance requirements of the heat-treatment-free high-vacuum pressure-casting aluminum alloy for large structural parts, the aluminum alloy production process is reduced, and the mechanical properties of the heat-treatment-free high-vacuum pressure-casting aluminum alloy are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aluminum alloys, in particular to a heat treatment-free high-vacuum die-casting aluminum alloy and a preparation method thereof. BACKGROUND

[0002] At present, for large die-casting structural parts for automobiles, the heat treatment process of AlSi10MnMg alloy can cause deformation and surface bubbling of the die-castings, especially as the die-castings continue to be large-sized, the difficulty of subsequent shaping and the scrap rate will be greatly improved, so the large die-casting structural parts are developing towards heat treatment-free. The heat treatment-free mechanical performance self-strengthening aluminum alloy has the characteristics that the parts do not need to be subjected to high-temperature solid solution treatment and artificial aging, and only natural aging is needed to obtain high strength and toughness.

[0003] CN115418537A discloses a heat treatment-free die-casting aluminum alloy and a preparation method and application thereof. Based on the total weight of the die-casting aluminum alloy, the die-casting aluminum alloy includes 6.0-8.0 wt% of Si, 0.3-1.2 wt% of Mg, 0.4-0.8 wt% of Cu, 0.1-0.3 wt% of Fe, 0.6-0.8 wt% of Mn, 0.05-0.20 wt% of Ti, 0.03-0.07 wt% of Sr, 0.03-0.07 wt% of Ce, 0.01-0.04 wt% of La, 0.01-0.1 wt% of Zr, less than or equal to 0.01 wt% of other impurity elements, and the balance of Al. The heat treatment-free die-casting aluminum alloy has significantly improved ultimate tensile strength, yield strength and elongation at break compared with existing automobile structural part alloys, and is suitable for producing large structural thin-walled parts of new energy electric vehicle bodies.

[0004] CN115287507A discloses a heat treatment-free aluminum alloy, a preparation method thereof, a structural part and application thereof. The aluminum alloy includes, by mass percentage, Si: 7.5-10.5%, Mg: 0.05-0.25%, Fe: 0-0.5%, Mn: 0.5-2.5%, Er: 0.05-0.35%, Ti: 0.05-0.3%, Ti / Sr: 2.5-7.5, and the balance of aluminum and other impurity elements, and the content of the other impurity elements is less than 0.01%. By adopting AlTiCB+Sr composite refining modification Al-Si-Mg alloy, the mechanical properties and connecting properties of the alloy are improved, by adjusting the Si / Mg ratio, the strength and elongation of the alloy are improved while the die-casting performance of the alloy is ensured, by adding trace element Er and simultaneously refining the coarse metal phase and nano-strengthening phase of the structure, the comprehensive performance of the alloy is significantly improved, and the strength, toughness, connectivity and popularization of the product are considered.

[0005] However, the heat-free aluminum alloys obtained in the existing technology still have poor mechanical properties, and their resistance to sticking and shrinkage needs to be further improved. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide a heat-free high-vacuum die-cast aluminum alloy and its preparation method, so as to solve the problems that heat-free aluminum alloys still have poor mechanical properties and need to further improve their anti-sticking and shrinkage porosity capabilities.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a heat-free high-vacuum die-cast aluminum alloy, wherein the heat-free high-vacuum die-cast aluminum alloy comprises, by mass percentage: Si 6-8%, Fe 0.5-0.6%, Mn 0.6-0.8%, Mg 0.3-0.4%, Cu 0.6-0.9%, Ti 0.1-0.2%, Sr 0.02-0.05%, with the balance being Al and unavoidable impurities.

[0009] The heat-free high-vacuum die-cast aluminum alloy provided by this invention uses only eight alloying elements: Al, Si, Fe, Mn, Mg, Cu, Ti, and Sr. By adopting appropriate proportions, the produced aluminum alloy meets the performance requirements of heat-free high-vacuum die-cast aluminum alloys for large structural components, reduces the aluminum alloy production process, and improves the mechanical properties of heat-free high-vacuum die-cast aluminum alloys.

[0010] Specifically, eutectic alloys are formed through Al and Si (eutectic point Si: 12.5%). Alloys with Si content less than 12.5% ​​are hypoeutectic alloys, with a microstructure consisting of Al solid solution and AlSi eutectic. Alloys with Si content greater than 12.5% ​​are hypereutectic alloys, with a microstructure consisting of Al solid solution, AlSi eutectic, and primary Si. Primary Si significantly reduces the alloy's mechanical properties, so a hypoeutectic composition, i.e., Si content less than 12.5%, must be selected. Within the hypoeutectic range, alloy fluidity increases with increasing Si content. However, once the Si content reaches 7.0%, increasing the Si content does not significantly improve fluidity. Furthermore, with increasing Si content, the presence of Fe, Cu, and trace amounts of P promotes the formation of primary Si, leading to reduced strength and poorer machinability. Therefore, the selection of Si content must first ensure the material's mechanical properties, and secondly, maximize fluidity to reduce the risk of casting defects. Thus, a Si content of 6.0-8.0% is chosen.

[0011] In this invention, the Si content in the heat-free high-vacuum die-cast aluminum alloy is 6-8% by mass, for example, it can be 6%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, or 8%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0012] In this invention, the Fe content in the heat-free high-vacuum die-cast aluminum alloy is 0.5-0.6% by mass, for example, it can be 0.5%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, or 0.6%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] In this invention, by controlling the Fe and Mn contents, the sticking phenomenon is greatly reduced. This is because as the Fe content increases, Fe exists in the alloy as needle-like and lamellar intermetallic compounds such as FeAl3 and β-AlFeSi, which reduces the mechanical properties of the alloy, increases hot cracking, and makes the casting brittle. Mn is dissolved in the Al solid solution, and the alloy strength increases with the increase of solid solubility. The intermetallic compounds formed by Mn and Al transform the harmful needle-like and lamellar FeAl3 and β-AlFeSi structures precipitated in the alloy into fine and dispersed (Fe,Mn)Al6 and α-Al(Fe,Mn)Si structures, which significantly improves the yield and tensile strength of the alloy and reduces the tendency to hot crack. However, the increase of Mn content in the formulation of this invention will cause segregation, resulting in a decrease in alloy performance.

[0014] In this invention, the Mn content in the heat-free high-vacuum die-cast aluminum alloy is 0.6-0.8% by mass, for example, it can be 0.6%, 0.61%, 0.62%, 0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.7%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, or 0.8%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] In this invention, the Mg content in the heat-free high-vacuum die-cast aluminum alloy is 0.3-0.4% by mass, for example, it can be 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, or 0.4%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0016] In this invention, the Cu content in the heat-free high-vacuum die-cast aluminum alloy is 0.6-0.9% by mass, for example, it can be 0.6%, 0.61%, 0.62%, 0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.7%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.8%, 0.81%, 0.82%, 0.83%, 0.84%, 0.85%, 0.86%, 0.87%, 0.88%, 0.89%, or 0.9%, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0017] In this invention, by controlling Mg and Cu within a specific range, finer AlFeMnSiMg and AlSiCuMg structures are formed within the alloy, thereby increasing strength without reducing plasticity, and improving yield strength, tensile strength, and machinability.

[0018] In this invention, the Ti content in the heat-free high-vacuum die-cast aluminum alloy is 0.1-0.2% by mass, for example, it can be 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.2%, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable. This allows the TiAl2 phase formed by Ti and Al to become the core of heterogeneous nucleation during aluminum alloy crystallization, effectively refining the grains, improving mechanical properties, and reducing the tendency for hot cracking.

[0019] In this invention, the Sr content in the heat-free high-vacuum die-cast aluminum alloy is 0.02-0.05% by mass, for example, it can be 0.02%, 0.021%, 0.022%, 0.023%, 0.024%, 0.025%, 0.026%, 0.027%, 0.028%, 0.029%, 0.03%, 0.031%, 0.032%, 0.033%, 0 ... The values ​​may be 0.034%, 0.035%, 0.036%, 0.037%, 0.038%, 0.039%, 0.04%, 0.041%, 0.042%, 0.043%, 0.044%, 0.045%, 0.046%, 0.047%, 0.048%, 0.049%, or 0.05%, but are not limited to the listed values. Other unlisted values ​​within this range also apply.

[0020] In this invention, Sr is a surface-active element that, in crystallography, can alter the behavior of intermetallic compounds. Sr has advantages such as long modification time, good effect, and reproducibility. Sr can prevent the formation of primary silicon caused by small amounts of Fe, Cu, and trace amounts of P, refine the eutectic silicon structure, and change the AlFeSi phase morphology, thereby improving mechanical properties such as tensile strength, yield strength, and elongation.

[0021] As a preferred embodiment of the present invention, the Si content in the heat-free high-vacuum die-cast aluminum alloy is 6.9-7.1% by mass.

[0022] Preferably, the Ti content in the heat-free high-vacuum die-cast aluminum alloy is 0.15-0.16% by mass.

[0023] As a preferred embodiment of the present invention, the mass ratio of Fe / Mn in the heat-free high-vacuum die-cast aluminum alloy is 1:(1.2-1.4), and the mass ratio of Cu / Mg is (2-2.3):1.

[0024] In this invention, the Fe / Mn mass ratio in the heat-free high-vacuum die-cast aluminum alloy is 1:(1.2-1.4), for example, it can be 1:1.2, 1:1.21, 1:1.22, 1:1.23, 1:1.24, 1:1.25, 1:1.26, 1:1.27, 1:1.28, 1:1.29, 1:1.3, 1:1.31, 1:1.32, 1:1.33, 1:1.34, 1:1.35, 1:1.36, 1:1.37, 1:1.38, 1:1.39 or 1:1.4, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0025] In this invention, the mass ratio of Cu / Mg in the heat-free high-vacuum die-cast aluminum alloy is (2-2.3):1, for example, it can be 2:1, 2.01:1, 2.02:1, 2.03:1, 2.04:1, 2.05:1, 2.06:1, 2.07:1, 2.08:1, 2.09:1, 2.1:1, 2.11:1, 2.12:1, 2.13:1, 2.1... The ratios are 4:1, 2.15:1, 2.16:1, 2.17:1, 2.18:1, 2.19:1, 2.2:1, 2.21:1, 2.22:1, 2.23:1, 2.24:1, 2.25:1, 2.26:1, 2.27:1, 2.28:1, 2.29:1, or 2.3:1, etc., but are not limited to the listed values. Other unlisted values ​​within this range also apply.

[0026] In a second aspect, the present invention provides a method for preparing a heat-free high-vacuum die-cast aluminum alloy as described in the first aspect, the method comprising the following:

[0027] The recycled aluminum, remelted material, and double-zero aluminum are melted, followed by a first heat preservation. Then, the first intermediate alloy is added according to the formula and a second heat preservation is performed. Finally, the second intermediate alloy is added and a third heat preservation is performed to remove slag.

[0028] After slag removal, a fourth heat preservation process is performed, followed by modification treatment, refining, degassing, and high-vacuum die casting to obtain a heat-free high-vacuum die-cast aluminum alloy.

[0029] As a preferred technical solution of the present invention, the mass ratio of the recycled aluminum, the remelted material and the double-zero aluminum is (1.8-2.2):(2.8-3.2):(4.8-5.2), for example, it can be 1.8:2.8:4.8, 2:3:5, 2:2.8:5, 2:3.2:5 or 2:2.9:5.2, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] As a preferred technical solution of the present invention, the temperature of the first heat preservation is 720-760℃, for example, it can be 720℃, 722℃, 724℃, 726℃, 728℃, 730℃, 732℃, 734℃, 736℃, 738℃, 740℃, 742℃, 744℃, 746℃, 748℃, 750℃, 752℃, 754℃, 756℃, 758℃ or 760℃, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0031] Preferably, the first heat preservation time is 30-40 minutes, for example, it can be 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes or 40 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] Preferably, the first intermediate alloy includes an aluminum-iron intermediate alloy, an aluminum-manganese intermediate alloy, an aluminum-silicon intermediate alloy, and an aluminum-copper intermediate alloy.

[0033] Preferably, the temperature of the second insulation is 720-740℃, for example, it can be 720℃, 721℃, 722℃, 723℃, 724℃, 725℃, 726℃, 727℃, 728℃, 729℃, 730℃, 731℃, 732℃, 733℃, 734℃, 735℃, 736℃, 737℃, 738℃, 739℃ or 740℃, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0034] Preferably, the second heat preservation time is 30-50 minutes, for example, it can be 30 minutes, 31 minutes, 32 minutes, 33 minutes, 34 minutes, 35 minutes, 36 minutes, 37 minutes, 38 minutes, 39 minutes, 40 minutes, 41 minutes, 42 minutes, 43 minutes, 44 minutes, 45 minutes, 46 minutes, 47 minutes, 48 ​​minutes, 49 minutes or 50 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] As a preferred embodiment of the present invention, the second intermediate alloy comprises an aluminum-titanium intermediate alloy and magnesium material.

[0036] Preferably, the temperature of the third insulation is 720-740℃, for example, it can be 720℃, 721℃, 722℃, 723℃, 724℃, 725℃, 726℃, 727℃, 728℃, 729℃, 730℃, 731℃, 732℃, 733℃, 734℃, 735℃, 736℃, 737℃, 738℃, 739℃ or 740℃, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] Preferably, the third heat preservation time is 10-20 minutes, for example, it can be 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes or 20 minutes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the temperature of the fourth insulation is 700-720℃, for example, it can be 700℃, 701℃, 702℃, 703℃, 704℃, 705℃, 706℃, 707℃, 708℃, 709℃, 710℃, 711℃, 712℃, 713℃, 714℃, 715℃, 716℃, 717℃, 718℃, 719℃ or 720℃, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0039] Preferably, the fourth heat preservation time is 30-40 minutes, for example, it can be 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes, 30 minutes.

[0040] As a preferred embodiment of the present invention, the modification treatment involves adding an aluminum-strontium master alloy to the molten aluminum at a nitrogen flow rate of 0.5-1 m³ / h. 3The process is carried out at a speed of / h and stirred at 700-900r / min for 5-10min, then allowed to stand for 20-30min before removing the slag;

[0041] In this invention, the nitrogen flow rate during the deterioration treatment is 0.5-1 m³ / h. 3 / h, for example, could be 0.5m 3 / h, 0.6m 3 / h, 0.7m 3 / h, 0.8m 3 / h, 0.9m 3 / h or 1m 3 / h, etc., but not limited to the listed values, other unlisted values ​​within this range also apply.

[0042] In this invention, the stirring speed during the deterioration treatment is 700-900 r / min, for example, it can be 700 r / min, 710 r / min, 720 r / min, 730 r / min, 740 r / min, 750 r / min, 760 r / min, 770 r / min, 780 r / min, 790 r / min, 800 r / min, 810 r / min, 820 r / min, 830 r / min, 840 r / min, 850 r / min, 860 r / min, 870 r / min, 880 r / min, 890 r / min or 900 r / min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] In this invention, the stirring time during the deterioration treatment is 5-10 min, for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] In this invention, the slag is removed after standing for 20-30 minutes during the deterioration treatment. For example, it can be 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes, or 30 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the refining process involves rotary jetting of argon gas for 5-6 minutes at a rotation speed of 280-450 r / min and a flow rate of 0.5-1.5 m³ / min. 3 / h.

[0046] In this invention, the refining time is 5 min, 5.1 min, 5.2 min, 5.3 min, 5.4 min, 5.5 min, 5.6 min, 5.7 min, 5.8 min, 5.9 min, or 6 min, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0047] In this invention, the rotational speed of the rotary argon gas during refining is 280-450 r / min, for example, it can be 280 r / min, 285 r / min, 290 r / min, 295 r / min, 300 r / min, 305 r / min, 310 r / min, 315 r / min, 320 r / min, 325 r / min, 330 r / min, 335 r / min, 340 r / min, 345 r / min, 350 r / min, 355 r / min, 360 r / min. 365r / min, 370r / min, 375r / min, 380r / min, 385r / min, 390r / min, 395r / min, 400r / min, 405r / min, 410r / min, 415r / min, 420r / min, 425r / min, 430r / min, 435r / min, 440r / min, 445r / min, or 450r / min, etc., but not limited to the listed values, other unlisted values ​​within this range also apply.

[0048] In this invention, the flow rate of argon gas in the rotary jet argon gas during refining is 0.5-1.5 m³ / s. 3 / h, for example, could be 0.5m 3 / h, 0.6m 3 / h, 0.7m 3 / h, 0.8m 3 / h, 0.9m 3 / h、1m 3 / h, 1.1m 3 / h, 1.2m 3 / h, 1.3m 3 / h, 1.4m 3 / h or 1.5m 3 / h, etc., but not limited to the listed values, other unlisted values ​​within this range also apply.

[0049] As a preferred technical solution of the present invention, the density index of the aluminum alloy liquid used in the high vacuum die casting is ≤1, for example, it can be 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2 or 0.1, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Preferably, the number of inclusions in the 20 fractures of the aluminum alloy liquid K mold used in the high vacuum die casting is ≤1, for example, it can be 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2 or 0.1, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0051] As a preferred embodiment of the present invention, the preparation method includes the following:

[0052] The recycled aluminum, remelted material, and double-zero aluminum are melted, followed by a first heat preservation. Then, the first intermediate alloy is added according to the formula and a second heat preservation is performed. Finally, the second intermediate alloy is added and a third heat preservation is performed to remove slag.

[0053] After slag removal, a fourth heat preservation is performed, followed by modification treatment, refining, degassing and high vacuum die casting to obtain heat-free high vacuum die-cast aluminum alloy.

[0054] The mass ratio of the recycled aluminum, the remelted material, and the double-zero aluminum is (1.8-2.2):(2.8-3.2):(4.8-5.2).

[0055] The first heat preservation temperature is 720-760℃; the first heat preservation time is 30-40 minutes; the first intermediate alloy includes aluminum-iron intermediate alloy, aluminum-manganese intermediate alloy, aluminum-silicon intermediate alloy, and aluminum-copper intermediate alloy; the second heat preservation temperature is 720-740℃; the second heat preservation time is 30-50 minutes; the second intermediate alloy includes aluminum-titanium intermediate alloy and magnesium material; the third heat preservation temperature is 720-740℃; the third heat preservation time is 10-20 minutes; the fourth heat preservation temperature is 700-720℃; the fourth heat preservation time is 30-40 minutes.

[0056] The modification treatment involves adding an aluminum-strontium master alloy to the molten aluminum under nitrogen flow rates of 0.5-1 m³ / h. 3 The process involves stirring at 700-900 rpm for 5-10 minutes, followed by settling for 20-30 minutes and skimming off the slag. The refining process involves rotary jetting of argon gas for 5-6 minutes at a speed of 280-450 rpm and a flow rate of 0.5-1.5 m³ / h. 3 / h; the density index of the aluminum alloy liquid used in the high vacuum die casting is ≤1; the number of inclusions in the 20 fractures of the aluminum alloy liquid used in the K mold during the high vacuum die casting is ≤1.

[0057] In this invention, the recycled aluminum refers to scrap aluminum parts generated during the use of automobiles, such as raw aluminum engine parts, including but not limited to cylinder blocks, cylinder heads, and covers.

[0058] In this invention, the recycled material can be excess aluminum material generated in the gating system and / or overflow system during the production of hypoeutectic aluminum alloy hot stamping parts. Specifically, it can be the casting of the hot stamping parts, the gating system, the overflow system, or the gating system and overflow system in normal production.

[0059] In this invention, the double-zero aluminum is A00 aluminum, with an aluminum mass percentage content >99.7%.

[0060] In this invention, high-vacuum die casting refers to a molding process in which liquid metal is filled into a mold cavity at extremely high speed under high pressure and then cooled and solidified under certain pressure to obtain a casting. For example, the MFT method is used. The MFT method uses a conventional die casting machine, and its process characteristics include the use of multiple runners and a large-area ingate to ensure that the molten metal can fill the mold cavity in a very short time.

[0061] Compared with existing technical solutions, the present invention has the following beneficial effects:

[0062] The heat-free high-vacuum die-cast aluminum alloy provided by this invention improves the performance of the heat-free high-vacuum die-cast aluminum alloy by designing the formula and utilizing the synergistic effect between the elements. The resulting heat-free high-vacuum die-cast aluminum alloy has a tensile strength ≥275.4MPa, a yield strength ≥145.1MPa, and an elongation ≥10.5%. Attached Figure Description

[0063] Figure 1 This is a SEM image of the microstructure of the aluminum alloy obtained in Example 1 of this invention.

[0064] The present invention will now be described in further detail. However, the examples described below are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims. Detailed Implementation

[0065] To better illustrate the present invention and facilitate understanding of its technical solutions, typical but non-limiting embodiments of the present invention are as follows:

[0066] Example 1

[0067] This embodiment provides a heat-free high-vacuum die-cast aluminum alloy, which comprises, by mass percentage: Si 7%, Fe 0.55%, Mn 0.7%, Mg 0.35%, Cu 0.75%, Ti 0.15%, Sr 0.035%, with the balance being Al and unavoidable impurities.

[0068] The preparation was carried out using the following method:

[0069] Recycled aluminum (engine aluminum parts: cylinder block, cylinder head, cover), remelted material (excess aluminum material generated in the gating system during the production of hypoeutectic aluminum alloy hot stamping parts), and double-zero aluminum (aluminum mass percentage of 99.8%) are melted, followed by a first heat preservation, then the first intermediate alloy is added according to the formula and a second heat preservation is performed, then the second intermediate alloy is added and a third heat preservation is performed, and slag removal is carried out.

[0070] After slag removal, a fourth heat preservation is performed, followed by modification treatment, refining, degassing and high vacuum die casting to obtain heat-free high vacuum die-cast aluminum alloy.

[0071] The mass ratio of the recycled aluminum, the remelted material, and the double-zero aluminum is 2:3:5;

[0072] The first holding temperature is 740℃; the first holding time is 35 min; the first intermediate alloy is an aluminum-iron intermediate alloy (AlFe20), an aluminum-manganese intermediate alloy (AlMn10), an aluminum-silicon intermediate alloy (AlSi20), and an aluminum-copper intermediate alloy (AlCu50); the second holding temperature is 720℃; the second holding time is 40 min; the second intermediate alloy includes an aluminum-titanium intermediate alloy (AlTi5) and magnesium material (magnesium ingot); the third holding temperature is 730℃; the third holding time is 15 min; the fourth holding temperature is 710℃; the fourth holding time is 35 min;

[0073] The modification treatment involves adding an aluminum-strontium master alloy to the molten aluminum under nitrogen flow rates of 0.75 m³ / h. 3 The process involves stirring at 800 rpm for 8 minutes, followed by settling for 25 minutes and then skimming off the slag. The refining process involves rotary argon injection for 5 minutes at a speed of 350 rpm and a flow rate of 1 m³ / h. 3 / h; the density index of the aluminum alloy liquid used in the high vacuum die casting is 1; the number of inclusions in the 20 fracture surfaces of the aluminum alloy liquid used in the high vacuum die casting is 1.

[0074] The mechanical properties of the obtained aluminum alloy are detailed in Table 1, and the SEM images of the microstructure of the obtained aluminum alloy are detailed in Table 1. Figure 1 .

[0075] Example 2

[0076] This embodiment provides a heat-free high-vacuum die-cast aluminum alloy, which comprises, by mass percentage: Si 8%, Fe 0.5%, Mn 0.6%, Mg 0.3%, Cu 0.6%, Ti 0.2%, Sr 0.05%, with the balance being Al and unavoidable impurities.

[0077] The preparation was carried out using the following method:

[0078] The recycled aluminum (engine aluminum parts: cylinder block, cylinder head, cover), remelted material (excess aluminum material generated in the gating system during the production of hypoeutectic aluminum alloy hot-dip dies), and double-zero aluminum (aluminum mass percentage of 99.8%) are then subjected to the first heat preservation, followed by the addition of the first intermediate alloy according to the formula and the second heat preservation, then the addition of the second intermediate alloy and the third heat preservation, and slag removal.

[0079] After slag removal, a fourth heat preservation is performed, followed by modification treatment, refining, degassing and high vacuum die casting to obtain heat-free high vacuum die-cast aluminum alloy.

[0080] The mass ratio of the recycled aluminum, the remelted material, and the double-zero aluminum is 1.8:3.2:4.8;

[0081] The first holding temperature is 760℃; the first holding time is 30 min; the first intermediate alloy includes aluminum-iron intermediate alloy (AlFe20), aluminum-manganese intermediate alloy (AlMn10), aluminum-silicon intermediate alloy (AlSi20), and aluminum-copper intermediate alloy (AlCu50); the second holding temperature is 730℃; the second holding time is 50 min; the second intermediate alloy includes aluminum-titanium intermediate alloy (AlTi5) and magnesium material (magnesium ingot); the third holding temperature is 720℃; the third holding time is 10 min; the fourth holding temperature is 720℃; the fourth holding time is 30 min;

[0082] The modification treatment involves adding an aluminum-strontium master alloy to the molten aluminum under nitrogen flow rate of 0.5 m³ / s. 3 The process involves stirring at 900 rpm for 5 minutes, followed by settling for 30 minutes and skimming off the slag. The refining process involves rotary argon injection for 6 minutes at a speed of 280 rpm and a flow rate of 1.5 m³ / h. 3 / h; the density index of the aluminum alloy liquid used in the high vacuum die casting is 0.5; the number of inclusions in the 20 fracture surfaces of the aluminum alloy liquid used in the high vacuum die casting is 0.5.

[0083] The mechanical properties of the obtained aluminum alloy material are detailed in Table 1.

[0084] Example 3

[0085] This embodiment provides a heat-free high-vacuum die-cast aluminum alloy, which comprises, by mass percentage: Si 6%, Fe 0.6%, Mn 0.8%, Mg 0.4%, Cu 0.9%, Ti 0.1%, Sr 0.02%, with the balance being Al and unavoidable impurities.

[0086] The preparation was carried out using the following method:

[0087] The recycled aluminum (engine aluminum parts: cylinder block, cylinder head, cover), remelted material (excess aluminum material generated in the overflow system during the production of hypoeutectic aluminum alloy hot stamping parts) and double-zero aluminum (aluminum mass percentage of 99.8%) are then subjected to the first heat preservation, followed by the addition of the first intermediate alloy according to the formula and the second heat preservation, then the addition of the second intermediate alloy and the third heat preservation, and slag removal.

[0088] After slag removal, a fourth heat preservation is performed, followed by modification treatment, refining, degassing and high vacuum die casting to obtain heat-free high vacuum die-cast aluminum alloy.

[0089] The mass ratio of the recycled aluminum, the scrap metal, and the double-zero aluminum is 2.2:2.8:5.2;

[0090] The first holding temperature is 720℃; the first holding time is 40 min; the first intermediate alloy includes aluminum-iron intermediate alloy (AlFe20), aluminum-manganese intermediate alloy (AlMn10), aluminum-silicon intermediate alloy (AlSi20), and aluminum-copper intermediate alloy (AlCu50); the second holding temperature is 740℃; the second holding time is 30 min; the second intermediate alloy includes aluminum-titanium intermediate alloy (AlTi5) and magnesium material (magnesium ingot); the third holding temperature is 740℃; the third holding time is 20 min; the fourth holding temperature is 700℃; the fourth holding time is 40 min;

[0091] The modification treatment involves adding an aluminum-strontium master alloy to the molten aluminum under nitrogen flow rate of 1 m³ / s. 3 The process involves stirring at 700 rpm for 10 minutes, followed by settling for 20 minutes and skimming off the slag. The refining process involves rotary argon injection for 5 minutes at a speed of 450 rpm and a flow rate of 0.5 m³ / h. 3 / h; the density index of the aluminum alloy liquid used in the high vacuum die casting is 1; the number of inclusions in the 20 fracture surfaces of the aluminum alloy liquid used in the high vacuum die casting is 1.

[0092] The mechanical properties of the obtained aluminum alloy material are detailed in Table 1.

[0093] Example 4

[0094] The only difference from Example 1 is that the Fe content is 0.6% and the Mn content is 0.6%, and the difference is replaced by Al element.

[0095] The mechanical properties of the obtained aluminum alloy material are detailed in Table 1.

[0096] Example 5

[0097] The only difference from Example 1 is that the Cu content is 0.6%, and the difference is replaced by Al element.

[0098] The mechanical properties of the obtained aluminum alloy material are detailed in Table 1.

[0099] Example 6

[0100] The only difference from Example 1 is that the Fe content is 0.3%, and the variation is replaced by Al element.

[0101] The mechanical properties of the obtained aluminum alloy material are detailed in Table 1.

[0102] Example 7

[0103] The only difference from Example 1 is that the Mg content is 0.8%, and the variation is replaced by Al element.

[0104] The mechanical properties of the obtained aluminum alloy material are detailed in Table 1.

[0105] Example 8

[0106] The only difference from Example 1 is that the Si content is 10%, and the variation is replaced by Al element.

[0107] The mechanical properties of the obtained aluminum alloy material are detailed in Table 1.

[0108] The mechanical properties of the aluminum alloy materials obtained in the above embodiments were tested in accordance with GB / T 228.1-2021.

[0109] Table 1

[0110] Tensile strength / MPa Yield strength / MPa Elongation / % Example 1 285.4 152.3 14.2 Example 2 288.2 145.1 10.5 Example 3 275.4 157.1 12.4 Example 4 222.4 118.3 8.2 Example 5 234.2 108.3 9.2 Example 6 226.4 114.5 6.8 Example 7 212.6 121.2 7.8 Example 8 224.8 134.5 8.8

[0111] As can be seen from the results of the above embodiments, the heat-free high-vacuum die-cast aluminum alloy provided by the present invention uses only 8 alloying elements: Al, Si, Fe, Mn, Mg, Cu, Ti, and Sr. By adopting appropriate proportions, the produced aluminum alloy meets the performance requirements of heat-free high-vacuum die-cast aluminum alloy for large structural parts, reduces the aluminum alloy production process, and improves the mechanical properties of heat-free high-vacuum die-cast aluminum alloy.

[0112] The present invention is described in detail through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0113] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0114] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0115] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A heat-free, high-vacuum die-cast aluminum alloy, characterized in that, The heat-free high-vacuum die-cast aluminum alloy comprises, by weight percentage: Si 6-8%, Fe 0.5-0.6%, Mn 0.6-0.8%, Mg 0.3-0.4%, Cu 0.6-0.9%, Ti 0.1-0.2%, Sr 0.02-0.05%, with the balance being Al and unavoidable impurities; The mass ratio of Fe / Mn in the heat-free high-vacuum die-cast aluminum alloy is 1:(1.2-1.4), and the mass ratio of Cu / Mg is (2-2.3):

1.

2. The heat-free high-vacuum die-cast aluminum alloy as described in claim 1, characterized in that, The heat-free high-vacuum die-cast aluminum alloy contains 6.9-7.1% Si by mass.

3. The heat-free high-vacuum die-cast aluminum alloy as described in claim 1, characterized in that, The Ti content in the heat-free high-vacuum die-cast aluminum alloy is 0.15-0.16% by mass.

4. A method for preparing a heat-free high-vacuum die-cast aluminum alloy as described in any one of claims 1-3, characterized in that, The preparation method includes the following: The recycled aluminum, remelted material, and double-zero aluminum are melted, followed by a first heat preservation. Then, the first intermediate alloy is added according to the formula and a second heat preservation is performed. Finally, the second intermediate alloy is added and a third heat preservation is performed to remove slag. After slag removal, a fourth heat preservation process is performed, followed by modification treatment, refining, degassing, and high-vacuum die casting to obtain a heat-free high-vacuum die-cast aluminum alloy.

5. The preparation method according to claim 4, characterized in that, The mass ratio of the recycled aluminum, the remelted material, and the double-zero aluminum is (1.8-2.2):(2.8-3.2):(4.8-5.2).

6. The preparation method according to claim 4, characterized in that, The temperature of the first insulation is 720-760℃.

7. The preparation method according to claim 4, characterized in that, The first heat preservation time is 30-40 minutes.

8. The preparation method according to claim 4, characterized in that, The first intermediate alloy includes aluminum-iron intermediate alloy, aluminum-manganese intermediate alloy, aluminum-silicon intermediate alloy, and aluminum-copper intermediate alloy.

9. The preparation method according to claim 4, characterized in that, The second insulation temperature is 720-740℃.

10. The preparation method according to claim 4, characterized in that, The second heat preservation time is 30-50 minutes.

11. The preparation method according to claim 4, characterized in that, The second intermediate alloy comprises an aluminum-titanium intermediate alloy and magnesium.

12. The preparation method according to claim 4, characterized in that, The temperature of the third insulation is 720-740℃.

13. The preparation method according to claim 4, characterized in that, The third heat preservation time is 10-20 minutes.

14. The preparation method according to claim 4, characterized in that, The temperature of the fourth insulation is 700-720℃.

15. The preparation method according to claim 4, characterized in that, The fourth heat preservation time is 30-40 minutes.

16. The preparation method according to claim 4, characterized in that, The modification treatment involves adding an aluminum-strontium master alloy to the molten aluminum under nitrogen flow rates of 0.5-1 m³ / h. 3 The process is carried out at a speed of / h and stirred at 700-900r / min for 5-10min, then allowed to stand for 20-30min before removing the slag.

17. The preparation method according to claim 4, characterized in that, The refining process involves rotary jetting of argon gas for 5-6 minutes at a rotation speed of 280-450 r / min and a flow rate of 0.5-1.5 m³ / min. 3 / h.

18. The preparation method according to claim 4, characterized in that, The density index of the aluminum alloy liquid used in the high vacuum die casting is ≤1.

19. The preparation method according to claim 4, characterized in that, The number of inclusions in the 20 fracture surfaces of the aluminum alloy liquid used in the high vacuum die casting process is ≤1.

20. The preparation method according to any one of claims 4-19, characterized in that, The preparation method includes the following: The recycled aluminum, remelted material, and double-zero aluminum are melted, followed by a first heat preservation. Then, the first intermediate alloy is added according to the formula and a second heat preservation is performed. Finally, the second intermediate alloy is added and a third heat preservation is performed to remove slag. After slag removal, a fourth heat preservation is performed, followed by modification treatment, refining, degassing and high vacuum die casting to obtain heat-free high vacuum die-cast aluminum alloy. The mass ratio of the recycled aluminum, the remelted material, and the double-zero aluminum is (1.8-2.2):(2.8-3.2):(4.8-5.2). The first heat preservation temperature is 720-760℃; the first heat preservation time is 30-40 minutes; the first intermediate alloy includes aluminum-iron intermediate alloy, aluminum-manganese intermediate alloy, aluminum-silicon intermediate alloy, and aluminum-copper intermediate alloy; the second heat preservation temperature is 720-740℃; the second heat preservation time is 30-50 minutes; the second intermediate alloy includes aluminum-titanium intermediate alloy and magnesium material; the third heat preservation temperature is 720-740℃; the third heat preservation time is 10-20 minutes; the fourth heat preservation temperature is 700-720℃; the fourth heat preservation time is 30-40 minutes. The modification treatment involves adding an aluminum-strontium master alloy to the molten aluminum under nitrogen flow rates of 0.5-1 m³ / h. 3 The process involves stirring at 700-900 rpm for 5-10 minutes, followed by settling for 20-30 minutes and skimming off the slag. The refining process involves rotary jetting of argon gas for 5-6 minutes at a speed of 280-450 rpm and a flow rate of 0.5-1.5 m³ / h. 3 / h; the density index of the aluminum alloy liquid used in the high vacuum die casting is ≤1; the number of inclusions in the 20 fractures of the aluminum alloy liquid used in the K mold during the high vacuum die casting is ≤1.

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