WO2022073301A1

WO2022073301A1 - Al-si alloy, preparation method for same, and applications thereof

Info

Publication number: WO2022073301A1
Application number: PCT/CN2020/137549
Authority: WO
Inventors: 李润霞; 郝建飞; 卞健从; 陈斌; 姜雄华; 于宝义
Original assignee: 东莞理工学院
Priority date: 2020-10-09
Filing date: 2020-12-18
Publication date: 2022-04-14
Also published as: CN112126827A; CN112126827B

Abstract

An Al-Si alloy, a preparation method for same, and applications thereof, related to the technical field of aluminum alloys. The Al-Si alloy, in terms of mass percent content, comprises Si 14-22%, Cu 2-5%, Mg 0.5-2.2%, Zr 0.15-0.25%, La 0.1-0.5%, Er 0.1-0.3%, Mn ≤ 0.2%, Fe ≤ 0.15%, and the remainder being Al and unavoidable impurities, where the content of each impurity among the unavoidable impurities is less than 0.01%. By adding trace amounts of Zr and compound rare earth elements La and Er to the alloy and, at the same time, controlling the contents of Si, Cu, and Mg in the alloy, the morphology of a Si phase is improved, crystals are refined, the alloy is structurally uniform and is provided with increased strength and improved wear resistance.

Description

A kind of Al-Si alloy and its preparation method and application

This application claims the priority of the Chinese patent application with the application number CN202011072743.1 and the invention title "An Al-Si alloy and its preparation method and application", which was submitted to the China Patent Office on October 9, 2020, and the entire contents of which are Incorporated herein by reference.

technical field

The invention relates to the technical field of aluminum alloy materials, in particular to an Al-Si alloy and a preparation method and application thereof.

Background technique

Cast Al-Si alloy is the most important series of cast aluminum alloys. Due to its low density, high specific strength, and excellent casting properties, corrosion resistance, wear resistance, weldability and thermal expansion, it is widely used. It is used in aerospace, automobile, machinery and other industries to produce large, medium and small sizes with complex shapes, thin walls, high requirements for corrosion resistance, high air tightness, medium and high static loads or impact loads, and requirements to work at higher temperatures. casting. For example, in the prior art, components such as automobile engines are usually die-casted using hypereutectic Al-Si alloys, but engine components prepared from existing alloy components have certain limitations in terms of strength and wear resistance. A small amount of Cu and Mg elements are added to the hypereutectic Al-Si alloy to form strengthening phases such as Al ₂ Cu, Mg ₂ Si and Al-Si-Cu-Mg in the alloy, which can improve the strength of the alloy to a certain extent. However, due to the high content of Si in the alloy, a coarse bulk Si phase and a fibrous eutectic Si phase will be formed in the matrix after forming, which has a large splitting effect on the matrix, and the strength and wear resistance of the alloy need to be improved. .

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an Al-Si alloy and its preparation method and application. The alloy provided by the present invention has higher strength and better wear resistance.

In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solutions:

The invention provides an Al-Si alloy, which in terms of mass percentage, comprises Si 14-22%, Cu 2-5%, Mg 0.5-2.2%, Zr 0.15-0.25%, La 0.1-0.5%, Er 0.1 to 0.3%, Mn≤0.2%, Fe≤0.15%, and the balance is Al and inevitable impurities. Among the inevitable impurities, the content of each impurity is less than 0.01%.

Preferably, it includes Si 15.5-18%, Cu 2.5-4.5%, Mg 0.5-1.8%, Zr 0.18-0.22%, La 0.1-0.3%, Er 0.1-0.2%, Mn 0.15-0.2%, Fe 0.1-0.15 %, the balance is Al and inevitable impurities.

The present invention provides the preparation method of the Al-Si alloy described in the above technical solution, comprising the following steps:

Smelting the prepared raw materials according to the composition of the Al-Si alloy to obtain an alloy liquid;

Refining the alloy liquid to obtain a refining liquid;

Under the action of an ultrasonic/electromagnetic compound field, the refining liquid is shaped based on a semi-continuous casting process to obtain an Al-Si alloy.

Preferably, the preparation raw materials include pure aluminum ingots and master alloys;

The smelting includes: first smelting pure aluminum ingots, and after part of the pure aluminum ingots is melted, adding the master alloy for second smelting.

Preferably, the temperature of the first smelting is 720-770° C. and the time is 1-5 h, and the temperature of the second smelting is 700-760° C. and the time is 1-4 h.

Preferably, the part of the pure aluminum ingot accounts for 45-65% of the total mass of the pure aluminum ingot.

Preferably, the refining is powder refining.

Preferably, the operating parameters of the powder refining include: the rotation speed of the deaerator is 100-140 rpm, the inlet pressure is 0.2-0.6 MPa, the powder output is 1-3.5 kg/min, and the refining time is 10-40 min.

Preferably, the operating parameters of the forming process include: the casting temperature is 680-720°C, the ultrasonic power is 300-360W, the ultrasonic frequency is 15-20kHz, the electromagnetic frequency is 20-30kHz, and the electromagnetic strength is 120-150A; When the cooling water pressure is 200～250m ³ /h, the speed of dummy is 100～180mm/min.

Preferably, after the forming process, it also includes:

The alloy billet obtained after the forming treatment is subjected to heat treatment to obtain a semi-solid billet;

Squeeze casting the semi-solid billet to obtain an alloy ingot;

The alloy ingot is quenched to obtain a quenched alloy ingot;

The quenched alloy ingot is subjected to T6 heat treatment to obtain an Al-Si alloy.

Preferably, the heating treatment is performed in an intermediate frequency induction furnace, the temperature of the heating treatment is 570-600° C., and the time is 15-30 min.

Preferably, the operating parameters of the squeeze casting include: a specific pressure of 580-620 MPa, a pressure holding time of 40-60 s, and an extrusion speed of 5-12 mm/s.

Preferably, the time of the quenching treatment is 30-100s; the quenching medium used in the quenching treatment is a 10wt% NaCl aqueous solution, and the temperature of the NaCl aqueous solution is 17-28°C.

Preferably, the T6 heat treatment includes solution treatment and aging treatment performed in sequence; the temperature of the solution treatment is 500-525°C, and the time is 20-100min; the temperature of the aging treatment is 170-190°C, and the time is 170-190°C. For 8 ~ 12h.

The present invention provides the application of the Al-Si alloy described in the above technical solution or the Al-Si alloy prepared by the preparation method described in the above technical solution in auto parts.

The invention provides an Al-Si alloy, which in terms of mass percentage, comprises Si 14-22%, Cu 2-5%, Mg 0.5-2.2%, Zr 0.15-0.25%, La 0.1-0.5%, Er 0.1 to 0.3%, Mn≤0.2%, Fe≤0.15%, and the balance is Al and inevitable impurities. Among the inevitable impurities, the content of each impurity is less than 0.01%. By adding a small amount of Zr, La and Er into the alloy and simultaneously controlling the content of Si, Cu and Mg in the alloy, the present invention can improve the Si phase morphology, refine the crystal grains, and have uniform alloy structure, high strength and high strength. Better abrasion resistance. The results of the examples show that the tensile strength of the Al-Si alloy provided by the present invention reaches 362 MPa, the yield strength reaches 287 MPa, the elongation is 3.6%, the hardness value is 187HB, and the friction coefficient is 0.331, which can meet the performance of automobile parts. Require.

The invention provides the preparation method of the Al-Si alloy, which comprises the following steps: smelting the preparation raw materials according to the composition of the Al-Si alloy to obtain an alloy liquid; refining the alloy liquid to obtain a refining liquid; Under the action of an electromagnetic compound field, the refining liquid is shaped based on a semi-continuous casting process to obtain an Al-Si alloy. Under the action of the ultrasonic/electromagnetic compound field, the invention prepares the Al-Si alloy based on the semi-continuous casting process, the alloy segregation is improved, the utilization rate of raw materials is high, the grain size is small, the structure is uniform, and the wear resistance and mechanical properties are excellent. performance.

Further, the present invention adopts the semi-solid extrusion casting process to perform secondary processing on the alloy ingot obtained after the above-mentioned forming treatment, and adopts the T6 heat treatment process to process the quenched alloy ingot, so that the crystal grains in the alloy are more rounded, It is beneficial to further improve the elongation and other properties of the alloy.

Instruction drawings

Fig. 1 is the microstructure diagram of the Al-Si alloy prepared in Example 1;

Fig. 2 is the microstructure diagram of the Al-Si alloy prepared in Example 3;

FIG. 3 is a microstructure diagram of the Al-Si alloy prepared in Comparative Example 1. FIG.

Detailed ways

In terms of mass percentage, the Al-Si alloy provided by the present invention includes Si 14-22%, preferably 15.5-18%, more preferably 15.7-17%.

In terms of mass percentage, the Al-Si alloy provided by the present invention includes Cu 2-5%, preferably 2.5-4.5%, more preferably 2.8-3.6%.

In terms of mass percentage, the Al-Si alloy provided by the present invention includes 0.5-2.2% of Mg, preferably 0.5-1.8%, and more preferably 0.5-1.1%.

In terms of mass percentage, the Al-Si alloy provided by the present invention includes Zr 0.15-0.25%, preferably 0.18-0.22%, more preferably 0.18-0.2%.

In terms of mass percentage, the Al-Si alloy provided by the present invention includes La 0.1-0.5%, preferably 0.1-0.3%, more preferably 0.12-0.2%.

In terms of mass percentage, the Al-Si alloy provided by the present invention includes Er 0.1-0.3%, preferably 0.1-0.2%, more preferably 0.12-0.2%.

In terms of mass percentage, the Al-Si alloy provided by the present invention includes Mn≤0.2%, preferably 0.15-0.2%.

In terms of mass percentage, the Al-Si alloy provided by the present invention includes Fe≤0.15%, preferably 0.1-0.15%.

The Al-Si alloy provided by the present invention includes the balance of Al and inevitable impurities, and among the inevitable impurities, the content of each impurity is less than 0.01%.

In the present invention, Si, Cu and Mg are the main elements of the alloy, and these alloy elements have the effect of solid solution strengthening and aging precipitation strengthening. In addition, Mg and Si can precipitate Mg ₂ Si strengthening phase, and Cu and Al can precipitate Al ₂ Cu The strengthening phase further enhances the strength of the alloy. At the same time, the four alloy elements of Al, Si, Cu and Mg will also form the W (Al _x Mg ₅ Si ₄ Cu) and Q (Al ₅ Mg ₈ Si ₆ Cu ₂ ) strengthening phases. Specifically, the inventors found that when the Si content is lower than 14%, the Cu element content is lower than 2%, and the Mg element content is lower than 0.5%, the strength of the alloy decreases significantly, and the wear resistance also decreases; When the content is higher than 22%, the content of Cu element is higher than 5%, and the content of Mg element is higher than 2.2%, a coarse second phase will be formed inside the alloy, and the plasticity of the alloy casting will decrease sharply, which will affect the later cutting process. The present invention controls the content of Si, Cu and Mg within the above-mentioned ranges, which can balance the contradictory relationship between the strength, wear resistance and impact fracture toughness of the alloy, and is applied to automobile parts, which can meet the requirements of zero resistance for automobiles. Requirements for component strength, wear resistance and toughness.

In the present invention, Zr, La and Er are trace elements added in the alloy, wherein the addition of Zr can precipitate the Al ₃ Zr phase, which limits the precipitation of the coarse Mg ₅ Al ₈ phase along the grain boundary, while the Al ₃ Zr crystal structure and grain size The lattice constants are very similar to the matrix aluminum, and it is an excellent heterogeneous nucleation core of α-Al; when adding Zr and RE (La, Er) elements, the rare earth is easy to be enriched at the front of the solid/liquid interface, and it is enriched to a certain extent. At the same time, the Al ₃ RE compound is formed, and the supercooling of the composition increases the branching process, the secondary dendrites increase, and finally the dendrite spacing decreases and the grains are refined, especially when La and Er are used in combination, It has a better refining effect, forms a small second phase, and improves the strength of the alloy; in addition, the surface activity of rare earth elements is relatively large, and the enrichment at the front of the solid/liquid interface hinders the growth of α-Al grains The effect of Fe, which hinders the growth process of grains, promotes the refinement of grains; adding a small amount of Fe element to the alloy can form a hard needle-like phase in the alloy, strengthen the matrix, and improve the wear resistance of the alloy. A small amount of Mn element is added to the alloy, which can form the dispersed particles of Al ₆ Mn, prevent the recrystallization from coarsening, increase the recrystallization temperature, and at the same time form Al ₃ FeMn with the impure iron-containing impurities of the alloy, so that the compound form of Fe changes from The needle shape is transformed into a block shape, which can improve the toughness of the alloy to a certain extent.

Refining the alloy liquid to obtain a refining liquid;

In the present invention, the prepared raw materials are smelted according to the composition of the Al-Si alloy to obtain the alloy liquid. In the present invention, the preparation raw materials preferably include pure aluminum ingots, pure Mg and master alloys, and the master alloys preferably include Al-30%Si, Al-50%Cu, Al-10%Zr, Al-10%La , Al-10%Er, Al-30%Mn and Al-50%Fe. In the present invention, the smelting includes: first smelting pure aluminum ingots, and after part of the pure aluminum ingots is melted, adding the master alloy to carry out second smelting; the temperature of the first smelting is preferably 720-770° C. , more preferably 730-755°C, the time is preferably 1-6h, more preferably 2.5-4.5h; the temperature of the second smelting is preferably 700-760°C, more preferably 715-735°C, and the time is preferably 1 ~4h, more preferably 1.5~2.5h; the partial pure aluminum ingot preferably accounts for 45-65% of the total mass of the pure aluminum ingot, more preferably 50%. By adopting step-by-step smelting in the present invention, the smelting efficiency can be effectively improved, the heat loss can be reduced, and the phenomenon of over-burning caused by the smelting temperature being too high can be prevented.

After the alloy liquid is obtained, the present invention refines the alloy liquid to obtain a refining liquid. In the present invention, the refining is preferably powder refining, and the operating parameters of the powder refining include: the rotation speed of the degasser is preferably 100-140 rpm, more preferably 120-130 rpm; the inlet pressure is preferably 0.2-0.6 MPa, more preferably 0.3-0.5MPa; powder output is preferably 1-3.5kg/min, more preferably 2-3kg/min; refining time is preferably 10-40min, more preferably 20-30min. In the present invention, the refining agent used in the refining preferably includes Na ₃ AlF ₆ , Mg ₂ N ₃ , C ₂ Cl ₆ , NaCl and KCl, wherein the added amount of the Na ₃ AlF ₆ is preferably the total mass of the alloy liquid The addition amount of the Mg ₂ N ₃ is preferably 4-8% of the total mass of the alloy liquid, and the addition amount of the C ₂ Cl ₆ is preferably 2-4% of the total mass of the alloy liquid. The total addition amount of NaCl and KCl is preferably 2-4% of the total mass of the alloy liquid, and the mass ratio of NaCl and KCl is preferably 35:65. In the present invention, if the rotational speed of the degasser is too high, the inlet pressure is too large, and the refining time is too long, the alloy liquid will be splashed, which is easy to cause danger. If the speed of the degasser is too low, the inlet pressure is too small, and the refining time is too short, there will be residual gas and slag in the alloy liquid, which will affect the quality of the ingot. The present invention preferably controls the operation parameters of powder spray refining within the above range, which is beneficial to ensure good refining effect, greatly improve the cleanliness of the alloy, eliminate structural defects such as pores and inclusions, and ensure that the obtained alloy casting has no internal structure. Inclusions are generated to avoid inclusions affecting the properties of the alloy.

After the refining liquid is obtained, the present invention forms the refining liquid based on a semi-continuous casting process under the action of an ultrasonic/electromagnetic compound field to obtain an Al-Si alloy. In the present invention, before performing the forming treatment, the refining liquid is preferably filtered, and the filter plate used for the filtration is preferably a foam ceramic filter plate, and the porosity of the foam ceramic filter plate is preferably 80-120ppi. In the present invention, the operating parameters of the forming treatment include: the casting temperature is preferably 680-720°C, more preferably 700-720°C; the ultrasonic power is preferably 300-360W, more preferably 320-340W; the ultrasonic frequency is preferably 15～20kHz, more preferably 18～20kHz; electromagnetic frequency is preferably 20～30kHz, more preferably 22～25kHz; electromagnetic intensity is preferably 120～150A, more preferably 130～135A; ~250 m ³ /h, more preferably 220 to 235 m ³ /h; dummy speed is preferably 100 to 180 mm/min, more preferably 130 to 170 mm/min. In the present invention, when the ultrasonic power is small, the cavitation and acoustic flow effects are weak, and the effect of grain refinement cannot be achieved, but if the ultrasonic power is too large, the heat is transferred to the refining liquid to increase the temperature, and the greater the power The more obvious the heat transfer effect is, the longer the crystallization time is, which reduces the grain refinement effect to a certain extent, and at the same time wastes energy; when the electromagnetic frequency is too high, the stirring effect is relatively weak, and as the electromagnetic frequency decreases, the forced convection increases. The present invention preferably controls each operating parameter within the above range, and through the vibration of the ultrasonic field and the stirring effect of the low-frequency electromagnetic field, the internal structure of the alloy can be effectively refined, and the solute segregation in the alloy can be improved. In the present invention, when the cooling water pressure is too large, it is easy to cause the refining liquid to solidify too quickly, solute elements are partially segregated at the edge of the ingot, and the cooling water pressure is too small to easily cause the phenomenon of remelting and leakage; If the speed is too fast, it is easy to cause the phenomenon of remelting and leakage. If the speed of the ingot is too slow, it is easy to cause the refining liquid to solidify in the mold. In the present invention, each operating parameter is preferably controlled within the above-mentioned range, and the produced semi-continuously cast alloy ingot can be directly used in industrial production as an Al-Si alloy finished product with excellent performance.

In the present invention, in order to further improve the performance of the Al-Si alloy, the forming process preferably further includes:

Squeeze casting the semi-solid billet to obtain an alloy ingot;

The alloy ingot is quenched to obtain a quenched alloy ingot;

In the present invention, the alloy billet obtained after the forming treatment is subjected to heat treatment to obtain a semi-solid billet. In the present invention, the heating treatment is preferably carried out in an intermediate frequency induction furnace, and the temperature of the heating treatment is preferably 570-600°C, more preferably 580-590°C; the time is preferably 15-30 min, more preferably 15- 20min. In the present invention, the alloy ingot is preferably heated in an intermediate frequency induction furnace, which has fast heating speed and high efficiency, which can reduce the oxidation of the surface of the alloy ingot and help improve the quality of the alloy ingot; the present invention is preferably under the above temperature conditions. Heat treatment is beneficial to make the semi-solid billet have a suitable solid phase ratio (40-60%), and the solid phase ratio will not be too high or too low. If the solidification is too fast, the compactness of the alloy will be affected in the subsequent squeeze casting process. If the solid phase ratio is low, the roundness of the α-Al dendrites in the alloy structure after solidification will be poor, which will affect the properties of the alloy.

After the semi-solid billet is obtained, the present invention performs squeeze casting of the semi-solid billet to obtain an alloy ingot. In the present invention, the operating parameters of the squeeze casting include: the specific pressure is preferably 580-620MPa, more preferably 590-610MPa; the pressure holding time is preferably 40-60s, more preferably 45-55s; the extrusion speed is preferably It is 5-12 mm/s, More preferably, it is 8-12 mm/s. In the present invention, if the specific pressure is too low, the extrusion speed is slow, the semi-solid billet solidifies too fast during the extrusion process, the semi-solid billet cannot be completely punched, and the ingot has defects; if the specific pressure is too large, the extrusion speed is fast, The inside of the mold is easy to get involved in the gas and the semi-solid billet overflows. In the present invention, before performing the squeeze casting, the required mold is preferably preheated; the temperature of the preheating is preferably 280-320°C, more preferably 290-310°C; the time is preferably 50-100min, More preferably, it is 60 to 90 minutes. In the present invention, if the preheating temperature of the mold is too high, it is easy to cause the growth of crystal grains during the extrusion casting process, and if the mold temperature is too low, it is easy to cause the semi-solid blank to solidify too fast.

After the alloy ingot is obtained, in the present invention, the alloy ingot is quenched to obtain a quenched alloy ingot. In the present invention, the quenching treatment is to place the alloy ingot obtained after squeeze casting in a quenching medium for rapid cooling. In the present invention, the time of the quenching treatment is preferably 30-100s, more preferably 30-70s. In the present invention, the time of the quenching treatment refers to the time that the alloy ingot is in the quenching medium; the quenching medium It is preferably a 10wt% NaCl aqueous solution, and the temperature of the NaCl aqueous solution is 17-28°C, more preferably 18-25°C. After the quenching treatment, in the present invention, the obtained quenched alloy ingot is preferably placed in a ventilated place to air dry naturally. In the present invention, the above-mentioned NaCl aqueous solution is preferably used for cooling, which can significantly increase the cooling rate, enable the alloy ingot to be sufficiently and rapidly cooled, and rapidly form a supersaturated solid solution inside the alloy, which lays a good foundation for the subsequent heat treatment process.

After the quenched alloy ingot is obtained, the present invention performs T6 heat treatment on the quenched alloy ingot to obtain an Al-Si alloy. In the present invention, the T6 heat treatment preferably includes solution treatment and aging treatment performed in sequence; the temperature of the solution treatment is preferably 500-525°C, more preferably 515-525°C; the time is preferably 20-100min, It is further preferably 30-90 min; the temperature of the aging treatment is preferably 170-190°C, more preferably 175-190°C; the time is preferably 8-12h, more preferably 10-12h. In the present invention, due to the combined action of the ultrasonic/electromagnetic compound field in the semi-continuous casting process, the internal structure of the alloy is uniform and the grain size is fine, and during the semi-solid extrusion casting forming process, the semi-solid billet has a large plastic deformation, As a result, the internal energy of the alloy is higher and the dislocation density is higher. Therefore, only a short time of solution treatment is needed to eliminate the internal stress inside the alloy. Finally, after aging treatment, a large number of fine and dispersed precipitates will be precipitated, which will hinder the movement of dislocations and produce dispersion strengthening, thereby further improving Al-Si Mechanical properties and wear resistance of alloys.

The present invention provides the application of the Al-Si alloy described in the above technical solution or the Al-Si alloy prepared by the preparation method described in the above technical solution in auto parts. The Al-Si alloy provided by the invention has low internal stress, smooth surface, uniform internal structure, small grain size and little difference in size, and at the same time has excellent performance, high strength and good wear resistance, and is used for auto parts , can meet the subsequent machining requirements, and at the same time can meet the requirements of the car for the performance of the internal parts of the body.

The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

In this embodiment, the Al-Si alloy is composed of the following components by mass percentage: Si 15.7%, Cu 2.8%, Mg 0.5%, Zr 0.18%, La 0.12%, Er 0.12%, Mn 0.2%, Fe 0.1%, and the remainder The amount is Al and unavoidable impurities, and the content of each impurity in the unavoidable impurities is less than 0.01%.

The preparation method of Al-Si alloy in the present embodiment comprises the following steps:

According to the formula of the Al-Si alloy, the industrial pure aluminum ingot was added to the melting furnace, the temperature was raised to 730 °C, and the temperature was maintained for 4.5 hours. At this time, the pure aluminum ingot was melted to half, and pure Mg and other intermediate alloys (specifically Al-30 %Si, Al-50%Cu, Al-10%Zr, Al-10%Er, Al-10%La, Al-30%Mn and Al-50%Fe), cool down to 715℃, heat preservation for 2.5h, get alloy liquid;

Insert the refining pipe of the degasser into the alloy liquid to carry out powder refining, so as to achieve degassing and slag removal, and obtain a refining liquid; wherein, the operation parameters of the powder refining include: the rotation speed of the degasser is 120rpm, the inlet pressure is 0.3MPa, the powder output is 2kg/min, and the refining time is 20min _; the refining agents used in the powder spray refining include _Na3AlF6 , _Mg2N3 , _C2Cl6 , _NaCl and _KCl , Among them, the addition amount of Na ₃ AlF ₆ is 3.5% of the total mass of the alloy liquid, the addition amount of Mg ₂ N ₃ is 4.8% of the total weight of the alloy liquid, and the addition amount of C ₂ Cl ₆ is 2.4% of the total weight of the alloy liquid, The total addition amount of NaCl and KCl is 2.4% of the total mass of the alloy liquid, and the mass ratio of the NaCl and KCl is 35:65;

Under the action of the ultrasonic/electromagnetic compound field, the refining solution is shaped based on the semi-continuous casting process to obtain an Al-Si alloy; wherein, the refining solution is filtered through a foam ceramic filter plate (porosity is 80ppi) before the shaping process. Filtering; the operating parameters of the forming treatment include: the casting temperature is 700°C, the ultrasonic power is 320W, the ultrasonic frequency is 18kHz, the electromagnetic frequency is 22kHz, and the electromagnetic strength is 130A ^; The ingot speed was 130 mm/min.

Example 2

The Al-Si alloy in this embodiment is composed of the following components by mass percentage: Si 16.1%, Cu 3.1%, Mg 0.7%, Zr 0.19%, La 0.14%, Er 0.12%, Mn 0.2%, Fe 0.1%, and the remainder The amount is Al and unavoidable impurities, and the content of each impurity in the unavoidable impurities is less than 0.01%.

According to the formula of Al-Si alloy, the industrial pure aluminum ingot was added to the melting furnace, the temperature was raised to 735 °C, and the temperature was maintained for 4 hours. At this time, the pure aluminum ingot was melted to half, and pure Mg and other intermediate alloys (specifically Al-30% Si, Al-50%Cu, Al-10%Zr, Al-10%Er, Al-10%La, Al-30%Mn and Al-50%Fe), cooled to 715°C, heat preservation and smelting for 3.5h to obtain alloy liquid;

Insert the refining pipe of the degasser into the alloy liquid to carry out powder refining, so as to achieve degassing and slag removal, and obtain a refining liquid; wherein, the operation parameters of the powder refining include: the rotation speed of the degasser is 125rpm, the inlet pressure is 0.32MPa, the powder output is 2.2kg/min, and the refining time is 25min; the refining agents used in the powder spray refining include Na ₃ AlF ₆ , Mg ₂ N ₃ , C ₂ Cl ₆ , NaCl and KCl , wherein the addition amount of Na ₃ AlF ₆ is 4.5% of the total mass of the alloy liquid, the addition amount of Mg ₂ N ₃ is 5.9% of the total weight of the alloy liquid, and the addition amount of C ₂ Cl ₆ is 3.2% of the total weight of the alloy liquid , the total amount of NaCl and KCl added is 3% of the total mass of the alloy liquid, and the mass ratio of NaCl and KCl is 35:65;

Under the action of the ultrasonic/electromagnetic compound field, the refining solution is shaped based on the semi-continuous casting process to obtain an alloy ingot; wherein, the refining solution is filtered through a foam ceramic filter plate (porosity is 100ppi) before the shaping process. The operating parameters of the forming treatment include: the casting temperature is 710°C, the ultrasonic power is 325W, the ultrasonic frequency is 18kHz, the electromagnetic frequency is 23kHz, and the electromagnetic intensity is 135A; the cooling water pressure during the ingot is 220m ³ /h, the ingot is drawn The speed is 130mm/min;

The alloy billet was placed in an intermediate frequency induction furnace, and heated at 580°C for 25min to obtain a semi-solid billet;

The mold is preheated at 290°C for 60 minutes, the semi-solid billet is transferred into the preheated mold, and squeeze casting is performed to obtain an alloy ingot; wherein, the operating parameters of the squeeze casting include: specific pressure is 590MPa, the holding time is 45s, and the extrusion speed is 9mm/s;

The alloy ingot is subjected to quenching treatment, wherein the quenching treatment time is 30s, the quenching medium is a 10wt% NaCl aqueous solution, and the temperature of the NaCl aqueous solution is 18°C; after the quenching treatment, it is naturally air-dried to obtain a quenched alloy ingot;

The quenched alloy ingot is sequentially subjected to solution treatment and aging treatment, and then cooled in a furnace to obtain an Al-Si alloy; wherein, the temperature of the solution treatment is 515° C., and the time is 75 minutes; the temperature of the aging treatment is 175°C for 12h.

Example 3

In this embodiment, the Al-Si alloy is composed of the following components by mass percentage: Si 17%, Cu 3.6%, Mg 1.1%, Zr 0.2%, La 0.2%, Er 0.2%, Mn 0.15%, Fe 0.12%, and the remainder The amount is Al and unavoidable impurities, and the content of each impurity in the unavoidable impurities is less than 0.01%.

According to the formula of the Al-Si alloy, the industrial pure aluminum ingot was added to the melting furnace, the temperature was raised to 745°C, and the temperature was maintained for 3 hours. At this time, the pure aluminum ingot was melted to half, and pure Mg and other intermediate alloys (specifically Al-30% Si, Al-50%Cu, Al-10%Zr, Al-10%Er, Al-10%La, Al-30%Mn and Al-50%Fe), cooled to 720℃, heat-smelting for 2h to obtain the alloy liquid;

Insert the refining pipe of the degasser into the alloy liquid to carry out powder refining, so as to realize degassing and slag removal, and obtain a refining liquid; wherein, the operation parameters of the powder refining include: the rotation speed of the degasser is 125rpm, the inlet pressure is 0.4MPa, the powder output is 2.8kg/min, and the refining time is 25min; the refining agents used in the powder spray refining include Na ₃ AlF ₆ , Mg ₂ N ₃ , C ₂ Cl ₆ , NaCl and KCl , wherein the addition amount of Na ₃ AlF ₆ is 4% of the total mass of the alloy liquid, the addition amount of Mg ₂ N ₃ is 4.6% of the total weight of the alloy liquid, and the addition amount of C ₂ Cl ₆ is 2.8% of the total weight of the alloy liquid , the total amount of NaCl and KCl added is 3.3% of the total mass of the alloy liquid, and the mass ratio of NaCl and KCl is 35:65;

Under the action of the ultrasonic/electromagnetic compound field, the refining liquid is shaped based on the semi-continuous casting process to obtain an alloy ingot; wherein, the refining liquid is filtered through a foam ceramic filter plate (porosity is 90ppi) before the shaping treatment. The operating parameters of the forming treatment include: the casting temperature is 710°C, the ultrasonic power is 330W, the ultrasonic frequency is 19kHz, the electromagnetic frequency is 23kHz, and the electromagnetic intensity is 133A; the cooling water pressure during the ingot is 230m ³ /h, the ingot is drawn The speed is 150mm/min;

The alloy billet is placed in an intermediate frequency induction furnace, and heated at 585° C. for 20 minutes to obtain a semi-solid billet;

The mold is preheated at 300° C. for 75 minutes, the semi-solid billet is transferred into the preheated mold, and squeeze casting is performed to obtain an alloy ingot; wherein, the operating parameters of the squeeze casting include: specific pressure is 600MPa, the holding time is 45s, and the extrusion speed is 10mm/s;

The alloy ingot is subjected to quenching treatment, wherein the quenching treatment time is 30s, the quenching medium is a 10wt% NaCl aqueous solution, and the temperature of the NaCl aqueous solution is 20°C; after the quenching treatment, it is naturally air-dried to obtain a quenched alloy ingot;

The quenched alloy ingot is sequentially subjected to solution treatment and aging treatment, and then cooled in a furnace to obtain an Al-Si alloy; wherein, the temperature of the solution treatment is 520° C., and the time is 60 minutes; the temperature of the aging treatment is 180 ℃, time is 12h.

Example 4

In this embodiment, the Al-Si alloy is composed of the following components by mass percentage: Si 15.7%, Cu 2.8%, Mg 1.0%, Zr 0.18%, La 0.12%, Er 0.12%, Mn 0.2%, Fe 0.15%, and the remainder The amount is Al and unavoidable impurities, and the content of each impurity in the unavoidable impurities is less than 0.01%.

According to the formula of the Al-Si alloy, the industrial pure aluminum ingot was added to the melting furnace, the temperature was raised to 755 °C, and the temperature was maintained for 2.5 hours. At this time, the pure aluminum ingot was melted to half, and pure Mg and other intermediate alloys (specifically Al-30 %Si, Al-50%Cu, Al-10%Zr, Al-10%Er, Al-10%La, Al-30%Mn and Al-50%Fe), cool down to 735℃, heat preservation for 1.5h, get alloy liquid;

Insert the refining pipe of the degasser into the alloy liquid to carry out powder refining, so as to achieve degassing and slag removal, and obtain a refining liquid; wherein, the operation parameters of the powder refining include: the rotation speed of the degasser is 130rpm, the inlet pressure is 0.5MPa, the powder output is 3kg/min, and the refining time is 30min _; the refining agents used in the powder spray refining include _Na3AlF6 , _Mg2N3 , _C2Cl6 , _NaCl and _KCl , Among them, the addition amount of Na ₃ AlF ₆ is 4.7% of the total mass of the alloy liquid, the addition amount of Mg ₂ N ₃ is 4.2% of the total weight of the alloy liquid, and the addition amount of C ₂ Cl ₆ is 2.1% of the total weight of the alloy liquid %, the total amount of NaCl and KCl added is 3.6% of the total mass of the alloy liquid, and the mass ratio of NaCl and KCl is 35:65;

Under the action of the ultrasonic/electromagnetic compound field, the refining solution is shaped based on the semi-continuous casting process to obtain an alloy ingot; wherein, the refining solution is filtered through a foam ceramic filter plate (porosity is 85ppi) before the shaping process. The operating parameters of the forming treatment include: the casting temperature is 720°C, the ultrasonic power is 340W, the ultrasonic frequency is 20kHz, the electromagnetic frequency is 25kHz, and the electromagnetic intensity is 135A; the cooling water pressure during the ingot is 235m ³ /h, the ingot is drawn The speed is 170mm/min;

The alloy billet is placed in an intermediate frequency induction furnace, and heated at 590° C. for 15 minutes to obtain a semi-solid billet;

The mold is preheated at 310° C. for 90 minutes, the semi-solid billet is transferred into the preheated mold, and extrusion casting is performed to obtain an alloy ingot; wherein, the operating parameters of the extrusion casting include: specific pressure is 610MPa, the holding time is 50s, and the extrusion speed is 12mm/s;

The alloy ingot is subjected to quenching treatment, wherein the quenching treatment time is 30s, the quenching medium is a 10wt% NaCl aqueous solution, and the temperature of the NaCl aqueous solution is 22°C; after the quenching treatment, it is naturally air-dried to obtain a quenched alloy ingot;

The quenched alloy ingot is sequentially subjected to solution treatment and aging treatment, and then cooled in a furnace to obtain an Al-Si alloy; wherein, the temperature of the solution treatment is 525° C., and the time is 30 minutes; the temperature of the aging treatment is 190°C for 10h.

Comparative Example 1

The Al-Si alloy in this comparative example is composed of the following components by mass percentage: Si 13.5%, Cu 0.5%, Mg 0.2%, and the balance is Al and unavoidable impurities. Among the unavoidable impurities, each impurity The content is lower than 0.01%.

The preparation method of Al-Si alloy in this comparative example comprises the following steps:

According to the formula of the Al-Si alloy, the industrial pure aluminum ingot was added to the melting furnace, the temperature was raised to 765 °C, and the temperature was maintained for 6 hours. At this time, the pure aluminum ingot was melted to half, and pure Mg and other intermediate alloys (specifically Al-30% Si and Al-50%Cu), cooled to 710°C, heat preservation and smelting for 3h to obtain alloy liquid;

Insert the refining pipe of the degasser into the alloy liquid to carry out powder refining, so as to achieve degassing and slag removal, and obtain a refining liquid; wherein, the operation parameters of the powder refining include: the rotation speed of the degasser is 100rpm, the inlet pressure is 0.2MPa, the powder output is 1kg/min, and the refining time is 15min; the refining agents used in the powder refining include Na ₃ AlF ₆ , Mg ₂ N ₃ , C ₂ Cl ₆ , NaCl and KCl, Among them, the addition amount of Na ₃ AlF ₆ is 3% of the total mass of the alloy liquid, the addition amount of Mg ₂ N ₃ is 4.1% of the total weight of the alloy liquid, and the addition amount of C ₂ Cl ₆ is 2% of the total weight of the alloy liquid, The total addition amount of NaCl and KCl is 2% of the total mass of the alloy liquid, and the mass ratio of the NaCl and KCl is 35:65;

Under the action of the ultrasonic/electromagnetic compound field, the refining solution is shaped based on the semi-continuous casting process to obtain an alloy ingot; wherein, the refining solution is filtered through a foam ceramic filter plate (porosity is 80ppi) before the shaping process. The operating parameters of the forming process include: the casting temperature is 690°C, the ultrasonic power is 280W, the ultrasonic frequency is 15kHz, the electromagnetic frequency is 20kHz, and the electromagnetic intensity is 115A; the cooling water pressure during the ingot is 200m ³ /h, the ingot is drawn The speed is 120mm/min;

The alloy billet is placed in an intermediate frequency induction furnace, and heated at 570° C. for 35 minutes to obtain a semi-solid billet;

The mold is preheated at 250° C. for 30 minutes, the semi-solid billet is transferred into the preheated mold, and squeeze casting is performed to obtain an alloy ingot; wherein, the operating parameters of the squeeze casting include: specific pressure is 560MPa, the holding time is 20s, and the extrusion speed is 15mm/s;

The alloy ingot is subjected to quenching treatment, wherein the quenching treatment time is 30s, the quenching medium is a 10wt% NaCl aqueous solution, and the temperature of the NaCl aqueous solution is 28°C; after the quenching treatment, it is naturally air-dried to obtain a quenched alloy ingot;

The quenched alloy ingot is sequentially subjected to solution treatment and aging treatment, and then cooled with a furnace to obtain an Al-Si alloy; wherein, the temperature of the solution treatment is 495° C., and the time is 100 min; the temperature of the aging treatment is 160 ℃, time is 12h.

Comparative Example 2

The Al-Si alloy in this comparative example is composed of the following mass percentages: Si 13.5%, Cu 0.5%, Mg 0.2%, Er 0.12%, Mn 0.15%, Fe 0.12%, and the balance is Al and unavoidable Impurities, among the unavoidable impurities, the content of each impurity is less than 0.01%.

According to the formula of Al-Si alloy, the industrial pure aluminum ingot is added to the melting furnace, the temperature is raised to 765°C, and the temperature is maintained for 6 hours. At this time, the pure aluminum ingot is melted to half, and pure Mg and other intermediate alloys (specifically Al-30% Si, Al-50%Cu, Al-10%Zr, Al-10%Er, Al-30%Mn and Al-50%Fe), cooled to 710°C, heat preservation and smelting for 3h to obtain alloy liquid;

Insert the refining pipe of the degasser into the alloy liquid to carry out powder refining, so as to achieve degassing and slag removal, and obtain a refining liquid; wherein, the operation parameters of the powder refining include: the rotation speed of the degasser is 100rpm, the inlet pressure is 0.2MPa, the powder output is 1kg/min, and the refining time is 15min; the refining agents used in the powder refining include Na ₃ AlF ₆ , Mg ₂ N ₃ , C ₂ Cl ₆ , NaCl and KCl, Among them, the addition amount of Na ₃ AlF ₆ is 3.5% of the total mass of the alloy liquid, the addition amount of Mg ₂ N ₃ is 7.2% of the total weight of the alloy liquid, and the addition amount of C ₂ Cl ₆ is 3.8% of the total weight of the alloy liquid, The total addition amount of NaCl and KCl is 3.9% of the total mass of the alloy liquid, and the mass ratio of the NaCl and KCl is 35:65;

Under the action of the ultrasonic/electromagnetic compound field, the refining solution is shaped based on the semi-continuous casting process to obtain an alloy ingot; wherein, the refining solution is filtered through a foam ceramic filter plate (porosity is 110ppi) before the shaping process. The operating parameters of the forming process include: the casting temperature is 690°C, the ultrasonic power is 280W, the ultrasonic frequency is 15kHz, the electromagnetic frequency is 20kHz, and the electromagnetic intensity is 115A; the cooling water pressure during the ingot is 200m ³ /h, the ingot is drawn The speed is 120mm/min;

The alloy ingot is subjected to quenching treatment, wherein the quenching treatment time is 30s, the quenching medium is a 10wt% NaCl aqueous solution, and the temperature of the NaCl aqueous solution is 25°C; after the quenching treatment, it is naturally air-dried to obtain a quenched alloy ingot;

The quenched alloy ingot is sequentially subjected to solution treatment and aging treatment, and then cooled in a furnace to obtain an Al-Si alloy; wherein, the temperature of the solution treatment is 495° C., and the time is 100 minutes; the temperature of the aging treatment is 160 ℃, time is 12h.

The alloys prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were tested for performance, wherein the tensile test was completed on the WGW-100H universal material testing machine, and the hardness test was completed on the HB3000 Brinell hardness tester. The performance test was completed on the MMU-5G material end face high temperature friction and wear testing machine.

Specifically, tensile strength is tested according to GB 228-2000 standard, yield strength is tested according to GB 228-2000 standard, elongation is tested according to GB/T 17737.308-2018 standard, hardness is tested according to GB/T 231.1-2009 standard, friction coefficient is tested according to GB/T 231.1-2009 standard GB 3142-82 standard test; the results are shown in Table 1.

It can be seen from Table 1 that the present invention ensures that the obtained alloy has high strength and wear resistance and excellent comprehensive performance by adding Mn, Zr and composite rare earth elements La and Er, and controlling the alloy composition within a specific content range.

Table 1 Performance test results of alloys prepared in Examples 1-4 and Comparative Examples 1-2

Figure 1 is a microstructure diagram of the Al-Si alloy prepared in Example 1. It can be seen from Figure 1 that the Al-Si alloy prepared by the semi-continuous casting process is relatively uniform due to the stirring effect of the composite physical field of ultrasonic and electromagnetic fields. .

Figure 2 is a microstructure diagram of the Al-Si alloy prepared in Example 3. It can be seen from Figure 2 that after semi-solid extrusion, the Al-Si alloy structure is further refined. The shape of α-Al is transformed into an equiaxed shape, so the mechanical properties are further improved.

Fig. 3 is a microstructure diagram of the Al-Si alloy prepared in Comparative Example 1. It can be seen from Fig. 3 that since no rare earth elements are added to the Al-Si alloy, the degree of grain refinement is weakened.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. It should be regarded as the protection scope of the present invention.

Claims

An Al-Si alloy, by mass percentage, comprises Si 14-22%, Cu 2-5%, Mg 0.5-2.2%, Zr 0.15-0.25%, La 0.1-0.5%, Er 0.1-0.3% , Mn≤0.2%, Fe≤0.15%, and the balance is Al and unavoidable impurities. Among the unavoidable impurities, the content of each impurity is lower than 0.01%.
The Al-Si alloy according to claim 1, characterized in that it comprises Si 15.5-18%, Cu 2.5-4.5%, Mg 0.5-1.8%, Zr 0.18-0.22%, La 0.1-0.3%, Er 0.1 ~ 0.2%, Mn 0.15 ~ 0.2%, Fe 0.1 ~ 0.15%, the balance is Al and inevitable impurities.
The preparation method of the described Al-Si alloy of claim 1 or 2, comprises the following steps:

Smelting the prepared raw materials according to the composition of the Al-Si alloy to obtain an alloy liquid;

Refining the alloy liquid to obtain a refining liquid;

Under the action of an ultrasonic/electromagnetic compound field, the refining liquid is shaped based on a semi-continuous casting process to obtain an Al-Si alloy.
The preparation method according to claim 3, wherein the preparation raw materials comprise pure aluminum ingots and master alloys;

The smelting includes: first smelting pure aluminum ingots, and after part of the pure aluminum ingots is melted, adding the master alloy for second smelting.
The preparation method according to claim 3, wherein the temperature of the first smelting is 720-770°C, and the time is 1-5h, and the temperature of the second smelting is 700-760°C, and the time is 1- 4h.
The preparation method according to claim 4, wherein the part of the pure aluminum ingot accounts for 45-65% of the total mass of the pure aluminum ingot.
The preparation method according to claim 3, wherein the refining is powder refining.
The preparation method according to claim 7, wherein the operation parameters of the powder refining include: the rotation speed of the degasser is 100-140 rpm, the inlet pressure is 0.2-0.6 MPa, and the powder output is 1-3.5 kg/min, and the refining time is 10 to 40 minutes.
The preparation method according to claim 3, wherein the operating parameters of the forming treatment include: a casting temperature of 680-720° C., an ultrasonic power of 300-360 W, an ultrasonic frequency of 15-20 kHz, and an electromagnetic frequency of 20-20 kHz. 30kHz, the electromagnetic intensity is 120～150A; the cooling water pressure is 200～250m 3 /h, and the speed of the dummy is 100～180mm/min.
The preparation method according to any one of claims 3 to 9, characterized in that, after the forming treatment, the method further comprises:

The alloy billet obtained after the forming treatment is subjected to heat treatment to obtain a semi-solid billet;

Squeeze casting the semi-solid billet to obtain an alloy ingot;

The alloy ingot is quenched to obtain a quenched alloy ingot;

The quenched alloy ingot is subjected to T6 heat treatment to obtain an Al-Si alloy.
The preparation method according to claim 10, wherein the heating treatment is performed in an intermediate frequency induction furnace, the temperature of the heating treatment is 570-600°C, and the time is 15-30 min.
The preparation method according to claim 10, wherein the operating parameters of the squeeze casting include: a specific pressure of 580-620 MPa, a pressure holding time of 40-60 s, and an extrusion speed of 5-12 mm/s.
The preparation method according to claim 10, wherein the time of the quenching treatment is 30-100s; the quenching medium used in the quenching treatment is 10wt% NaCl aqueous solution, and the temperature of the NaCl aqueous solution is 17-28 s °C.
The preparation method according to claim 10, wherein the T6 heat treatment comprises a solution treatment and an aging treatment performed in sequence; the temperature of the solution treatment is 500-525°C, and the time is 20-100min; the The temperature of aging treatment is 170～190℃, and the time is 8～12h.
Application of the Al-Si alloy according to claim 1 or 2 or the Al-Si alloy prepared by the preparation method according to any one of claims 3 to 14 in auto parts.