High-copper-content aluminum-silicon alloy and thermomechanical treatment method thereof

Abstract

The invention discloses a high-copper-content aluminum-silicon alloy and a thermomechanical treatment method thereof. The high-copper-content aluminum-silicon alloy comprises the following components in percentage by weight: 6.8 to 7.2 percent of Si, 2.8 to 3.2 percent of Cu, 0.45 to 0.55 percent of Mg, 0.02 to 0.04 percent of Sr, 0.02 to 0.04 percent of Ti, less than 0.15 percent of Fe and the balance of Al and inevitable impurities. The thermomechanical treatment method of solution treatment, friction stir treatment and aging treatment is adopted, the contradiction problem of second-phase overburning and eutectic silicon refining and spheroidizing of the high-copper-content aluminum-silicon alloy under the condition of a traditional heat treatment process is solved, synergistic improvement of the obdurability of the high-copper-content aluminum-silicon alloy is achieved, and the structure defects are remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy processing, more particularly, to a high-copper-content aluminum-silicon alloy and a thermo-mechanical processing method thereof, and especially to a thermo-mechanical processing method of a high-copper-content aluminum-silicon alloy based on friction stir processing. BACKGROUND

[0002] Under the trend of green manufacturing of high-end equipment, various structural parts also develop towards lightweight. Aluminum-silicon alloy has a broad application prospect in the fields of automobile manufacturing, rail transit and aerospace due to its small density, good casting performance and corrosion resistance; however, the coarse dendrites and coarse lamellar eutectic silicon particles in the microstructure of the aluminum-silicon alloy seriously affect the comprehensive performance of the aluminum-silicon alloy. In order to improve the strength and toughness of the alloy, alloying elements such as copper and magnesium are usually added to the aluminum-silicon alloy, and through the traditional T6 heat treatment process (two stages of solid solution treatment and artificial aging), copper-rich and magnesium-rich precipitation strengthening phases are precipitated, so that the mechanical properties are improved. However, for the traditional T6 heat treatment process applied to high-copper-content aluminum-silicon alloy, if the solid solution temperature is low, even if a longer solid solution time is used, the copper-containing phase cannot be fully solid-solved; if the solid solution temperature is too high, the Q-AlSiCuMg phase will melt to form holes and other defects; the contradiction between the full solid solution of the copper-containing phase and the melting of the Q-AlSiCuMg phase to form hole defects in the traditional T6 treatment process leads to the difficulty in synergistically improving the strength and toughness of the high-copper-content aluminum-silicon alloy after aging treatment, especially the plasticity and toughness.

[0003] For deformed aluminum alloys and some aluminum-based composites, heat treatment and deformation are often inseparable, and it is found in research that different combinations of heat treatment and deformation can change the microstructure of the material, thereby causing great differences in the mechanical properties of the material. Thermo-mechanical process (TMP) is a reasonable process that combines plastic deformation and heat treatment, and has gradually become one of the important manufacturing processes for aluminum alloys and their composites; in the thermo-mechanical process, plastic deformation causes an increase in the density of dislocations and vacancies in the material, and the distribution also changes, thereby changing the type, quantity, size and distribution of precipitates during heat treatment; the change in the precipitation behavior can affect the movement of dislocations and hinder the recrystallization of the material during deformation, thereby achieving the purpose of improving the strength and toughness of the alloy. Thermo-mechanical process was first used for steel, and for aluminum alloys, it was first studied in 1965, first for Al-Zn-Mg alloy, then for Al-Cu-Mg, Al-Zn-Mg-Cu and Al-Mg alloys, and in recent years, thermo-mechanical process has been used to improve the performance of Al-Li, Al-Cu-Li and other series of aluminum alloys.

[0004] Therefore, applying the thermomechanical processing technology to the synergistic strengthening and toughening design of aluminum-silicon alloys, developing a thermomechanical processing method including high-temperature solid solution treatment, friction stir processing and aging treatment can further break and spheroidize the eutectic silicon in high-copper-content aluminum-silicon alloys, weld the pores generated by the melting of Q phase during high-temperature solid solution treatment, eliminate the damage of pores to the plasticity of the alloy sheet, and improve the strength and plasticity of the material, thereby expanding its application range. However, there are few reports on the thermomechanical processing method of high-copper-content aluminum-silicon alloys by friction stir processing.

[0005] Chinese Patent Publication No. CN110129594A provides a method for strengthening hypoeutectic aluminum-silicon alloy by friction stir processing. Al-Si-Mg alloy is used as the main raw material for friction stir processing, and then the friction stir processed sheet is subjected to solid solution heat treatment and aging heat treatment (i.e., friction stir processing + heat treatment), thereby obtaining the strengthened hypoeutectic aluminum-silicon alloy. This alloy is quite different from the high-copper-content aluminum-silicon alloy of the present application, and the high-copper-content aluminum-silicon alloy has strong temperature and time sensitivity during friction stirring and heat treatment. Therefore, the traditional heat treatment and deformation processing cannot achieve the advantages of strength and toughness. Chinese Patent Publication No. CN115786784A discloses “A high-strength and high-toughness cast aluminum-silicon-copper-magnesium alloy, a preparation method thereof and an application thereof”, and Chinese Patent Publication No. CN116024482A discloses “A high-strength and high-toughness high-yield pressure die-cast aluminum-silicon alloy, a preparation method thereof and an application thereof”. Both of them only involve similar aluminum-silicon alloys, and do not mention the thermomechanical processing technology including friction stir processing in the preparation process. The document “Effect of friction stir processing and water cooling on grain refinement and deformation control of A356 cast aluminum alloy” only applies friction stir processing to Al-Si-Mg alloy, which does not contain Cu element, and does not involve thermomechanical processing technology and changes in tensile properties. The document “Optimizing the mechanical properties of Al–Si alloys through friction stir processing and rolling” also only applies friction stir processing and subsequent rolling (including warm rolling and cold rolling, etc.) to Al-Si-Mg alloy, which does not contain Cu element, and does not involve thermomechanical processing technology. The tensile properties are also relatively low.

[0006] In view of the above, it is urgent to develop a thermomechanical processing method suitable for high-copper-content aluminum-silicon alloys, which can solve the contradictory problem between the full solid solution of copper-containing phase and the formation of pore defects by the dissolution of Q-AlSiCuMg phase during the traditional T6 heat treatment process of high-copper-content aluminum-silicon alloys, and achieve the synergistic improvement of the strength and toughness of high-copper-content aluminum-silicon alloys. SUMMARY

[0007] In view of the problem of insufficient mechanical properties of high copper content aluminum silicon alloy caused by the existing heat treatment technology, the present application aims to provide a high copper content aluminum silicon alloy and a deformation heat treatment method thereof, which eliminates the hole defects caused by partial overburning of Q phase in the higher temperature solid solution process, promotes the full solid solution of Q phase and the full spheroidization of silicon particles, refines the microstructure of the alloy, effectively solves the contradiction between the fine spheroidization of eutectic silicon and the dissolution of copper-containing phase in the traditional T6 heat treatment process, and significantly improves the strength and toughness of the high copper content aluminum silicon alloy.

[0008] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0009] The first aspect of the present application provides a high copper content aluminum silicon alloy, which comprises the following components in percentage by weight: Si: 6.8-7.2%, Cu: 2.8-3.2%, Mg: 0.45-0.55%, Sr: 0.02-0.04%, Ti: 0.02-0.04%, Fe <0.15%, and the balance being Al and unavoidable impurities.

[0010] Preferably, the microstructure of the high copper content aluminum silicon alloy comprises eutectic silicon particles and residual Q phase.

[0011] Preferably, the size of the eutectic silicon particles is ≤2.8 μm, and the area ratio of the eutectic silicon particles in the alloy is ≤7.8%; and / or

[0012] The size of the residual Q phase is ≤2.6 μm, and the area ratio of the residual Q phase in the alloy is ≤0.8%.

[0013] Preferably, the performance satisfies: the tensile strength reaches 400 MPa or more, the yield strength reaches 320 MPa or more, and the elongation rate reaches 9% or more.

[0014] The second aspect of the present application provides a deformation heat treatment method of the high copper content aluminum silicon alloy as described in the first aspect of the present application, which comprises the following steps:

[0015] S1, preparing a high copper content aluminum silicon alloy plate according to the composition of the high copper content aluminum silicon alloy;

[0016] S2, performing solid solution treatment on the high copper content aluminum silicon alloy plate at 495-525 ℃, and then performing quenching treatment;

[0017] S3, performing friction stir processing on the quenched high copper content aluminum silicon alloy plate at a rotation speed of 600-1000 rpm;

[0018] S4, performing aging treatment on the high copper content aluminum silicon alloy plate after the friction stir processing.

[0019] Preferably, in the step S1, the raw materials for preparing the high-copper-content aluminum-silicon alloy plate are high-purity Al, high-purity Mg, Al-Cu intermediate alloy, Al-Si intermediate alloy and Al-Sr intermediate alloy.

[0020] Preferably, in the step S1, when preparing the high-copper-content aluminum-silicon alloy plate, the raw materials are melted into an aluminum melt and then cast into a slab, and the slab is cut into the high-copper-content aluminum-silicon alloy plate with a thickness of ≤3 mm.

[0021] Preferably, in the step S2, the solid solution treatment time is 10-14 h.

[0022] Preferably, the time interval between the step S2 and the step S3 is not more than 1 h.

[0023] Preferably, in the step S2, the quenching treatment is quenching the high-copper-content aluminum-silicon alloy plate after the solid solution treatment in warm water at 70-80 ℃, and the quenching treatment time is 10-15 min.

[0024] Preferably, in the step S3, the forward speed of the stir head used for the friction stir processing is 100-120 mm / min.

[0025] Preferably, in the step S4, in the aging treatment, the aging temperature is 175-180 ℃, and the treatment time is 4-8 h.

[0026] Compared with the prior art, the high-copper-content aluminum-silicon alloy and the deformation heat treatment method thereof provided by the application have the following beneficial effects:

[0027] 1. The deformation heat treatment (solid solution treatment + friction stir processing + artificial aging) process adopted by the application solves the contradictory problem of Q phase overburning and melting to produce hole defects and eutectic silicon refinement of the high-copper-content aluminum-silicon alloy under the traditional heat treatment process conditions, realizes the synergistic improvement of the strength and toughness of the high-copper-content aluminum-silicon alloy, and significantly reduces the organizational defects.

[0028] 2. The application not only further breaks and spheroidizes the eutectic silicon in the high-copper-content aluminum-silicon alloy, but also welds the holes produced by the melting of Q phase at a relatively high temperature during solid solution, eliminates the damage of the holes to the plasticity of the alloy plate, and thus can realize the substantial improvement of the strength and plasticity of the traditional alloy with low cost and simple alloying process, thereby expanding the application range thereof.

[0029] 3. Compared with the conventional T6 heat treatment process, the deformation heat treatment method involved in the application makes the tensile strength of the high-copper-content aluminum-silicon alloy be more than 400 MPa, the yield strength be more than 320 MPa, and the elongation be more than 9%, and thus the performance requirements of the aluminum alloy in the fields of automobile manufacturing, rail transit and aerospace complex structure castings can be completely met. Attached Figure Description

[0030] Figure 1 This is a temperature change diagram of the high copper content aluminum-silicon alloy and its deformation heat treatment method according to the present invention;

[0031] Figure 2 The following are metallographic diagrams of the alloys of Comparative Example 1 and Example 2: (a) is the metallographic diagram of the alloy of Comparative Example 1 after solution treatment at 495℃ for 12 hours; (b) is the metallographic diagram of the alloy of Comparative Example 2 after solution treatment at 515℃ for 12 hours; and (c) is the metallographic diagram of the alloy of Example 2 after deformation heat treatment.

[0032] Figure 3 This is the DSC chart of alloy 1 (Comparative Example 1);

[0033] Figure 4 This is a schematic diagram illustrating the mechanism of the effect of friction stir processing on eutectic silicon and voids in this invention. Detailed Implementation

[0034] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0035] To address the contradiction between the complete solid solution of the copper phase and the formation of voids due to the dissolution of the Q-AlSiCuMg phase during the traditional T6 heat treatment of high-copper-content aluminum-silicon alloys, this invention applies deformation heat treatment to the aluminum-silicon alloy processing to achieve a synergistic improvement in strength and toughness. An effective deformation heat treatment process is designed, incorporating high-temperature solution treatment, friction stir processing, and aging treatment. This process not only further breaks down and spheroidizes the eutectic silicon in the high-copper-content aluminum-silicon alloy but also welds the voids generated by the melting of the Q phase during high-temperature solution treatment, eliminating the damage to the plasticity of the alloy plate caused by the voids. This allows for a significant improvement in the strength and plasticity of a traditional alloy that is inexpensive and has a simple alloying process, thereby expanding its application range.

[0036] The present invention provides a high copper content aluminum-silicon alloy comprising the following components by weight percentage: Si: 6.8-7.2%, Cu: 2.8-3.2%, Mg: 0.45-0.55%, Sr: 0.02-0.04%, Ti: 0.02-0.04%, Fe < 0.15%, with the balance being Al and unavoidable impurities.

[0037] The design principles of each component in the high copper content aluminum-silicon alloy of this invention are as follows:

[0038] Si: form eutectic silicon organization in hypoeutectic alloy, increase casting alloy fluidity, etc.; Cu: add high content to form Q-AlSiCuMg and Al2Cu nano precipitated phase by aging, improve alloy strength, but will significantly reduce alloy plasticity; In addition, it will also cause the formation of hole defects during casting and heat treatment; Mg: form Mg2Si phase with Si, and Q-AlSiCuM phase with Cu and Si, improve alloy strength. Sr: modify the morphology of coarse lamellar eutectic silicon into fine fibrous; Ti: refine the grain structure of the alloy; Fe: harmful elements that cannot be removed from the cast alloy have an impact on mechanical properties, especially plasticity.

[0039] The microstructure of the high-copper-content aluminum-silicon alloy includes eutectic silicon and residual Q phase; the size of the eutectic silicon is ≤2.8 μm, and the area ratio of the eutectic silicon in the alloy is ≤7.8%; the size of the residual Q phase is ≤2.6 μm, and the area ratio of the residual Q phase in the alloy is ≤0.8%. In the high-copper-content aluminum-silicon alloy, the size of the hole caused by the melting of the Q phase is <1 μm, and the area ratio is close to 0.

[0040] The performance of the high-copper-content aluminum-silicon alloy satisfies: the tensile strength reaches more than 400 MPa, the yield strength reaches more than 320 MPa, and the elongation rate reaches more than 9%.

[0041] In combination with Figure 1 The application also provides a method for the deformation heat treatment of the high-copper-content aluminum-silicon alloy, which comprises the following steps:

[0042] S1, preparing a high-copper-content aluminum-silicon alloy plate according to the composition of the high-copper-content aluminum-silicon alloy;

[0043] Specifically, raw materials are configured according to the composition of the high-copper-content aluminum-silicon alloy, the raw materials can be selected from high-purity Al ingots, high-purity Mg ingots, Al-Cu intermediate alloy ingots, Al-Si intermediate alloy ingots, Al-Sr intermediate alloy rods, Al-Ti-B intermediate alloy rods, etc., the raw materials are melted into aluminum melt in a traditional resistance furnace, a degassing refining process is implemented according to a conventional process, the aluminum melt after melting is cast into a slab with a thickness of 20±5 mm, and the slab is cut into a plurality of high-copper-content aluminum-silicon alloy plates with a thickness ≤3 mm.

[0044] S2, performing solid solution treatment on the high-copper-content aluminum-silicon alloy plate at 495-525 ℃, and then performing quenching treatment;

[0045] Specifically, the high-copper-content aluminum-silicon alloy plate is subjected to solid solution treatment at 495-525 ℃, and the solid solution treatment time is 10-14 h; then quenching treatment is performed, and the high-copper-content aluminum-silicon alloy plate after solid solution treatment is subjected to quenching treatment in warm water at 70-80 ℃, and the quenching treatment time is 10-15 min.

[0046] S3, the quenched high copper content aluminum silicon alloy plate is subjected to a friction stir processing at a rotational speed of 600-1000 rpm, wherein the forward speed of the stir head used in the friction stir processing is 100-120 mm / min.

[0047] In combination Figure 4 As shown in the figure, before the friction stir processing, a large number of holes and eutectic silicon along the grain boundary are generated by only the solid solution treatment; after the friction stir processing, the eutectic silicon is further broken and spheroidized due to the large shear force and temperature generated by the friction stir processing, and the holes generated due to the melting of Q phase are welded, so that the damage of the holes to the plasticity of the alloy is eliminated, and the improvement of the plasticity is ensured.

[0048] In the above process, the time interval between the solid solution treatment of step S2 and the friction stir processing of step S3 should not exceed 1 h, so as to prevent the influence of natural aging.

[0049] S4, the high copper content aluminum silicon alloy plate after the friction stir processing is subjected to an aging treatment; in the aging treatment, the aging temperature is 175-180℃, and the treatment time is 4-8 h.

[0050] The high copper content aluminum silicon alloy and the method for its deformation heat treatment according to the present application will be further described below in combination with specific examples.

[0051] Example 1

[0052] The composition and chemical components of the high copper content aluminum silicon alloy of the present example are as follows: Si: 6.90%, Cu: 2.96%, Mg: 0.54%, Sr: 0.04%, Fe: 0.09%, Ti: 0.02%, and the balance is Al and unavoidable impurities.

[0053] The method for the deformation heat treatment of the high copper content aluminum silicon alloy of the present example comprises the following steps:

[0054] (1) The raw materials are configured according to the composition of the high copper content aluminum silicon alloy, and high-purity Al ingot, high-purity Mg ingot, Al-50Cu (mass fraction, 50%, same below) intermediate alloy ingot, Al-20Si intermediate alloy ingot, Al-10Sr intermediate alloy rod, and Al-5Ti-1B intermediate alloy rod are selected as raw materials, and the aluminum melt after melting is cast into a slab with a thickness of 20 mm, and cut into several high copper content aluminum silicon alloy plates with a thickness of 3 mm;

[0055] (2) The high copper content aluminum silicon alloy plate is subjected to a solid solution treatment, and the solid solution treatment is performed at a temperature of 515℃ for 12 h;

[0056] (3) the high copper content aluminum silicon alloy after solution treatment is quenched in 70℃ warm water for 10 minutes;

[0057] (4) the high copper content aluminum silicon alloy after quenching is subjected to friction stir processing at a rotation speed of 600 rpm, the forward speed of the stirring head used in the friction stir processing is 100 mm / min;

[0058] (5) the high copper content aluminum silicon alloy after friction stir processing is immediately aged at a temperature of 175℃ for 4h.

[0059] Example 2

[0060] The high copper content aluminum silicon alloy of the present example has the same composition and chemical components as in Example 1.

[0061] The method for deformation heat treatment of the high copper content aluminum silicon alloy of the present example comprises the following steps:

[0062] (1) raw materials are configured according to the composition of the high copper content aluminum silicon alloy, high-purity Al ingot, high-purity Mg ingot, Al-50Cu (mass fraction, 50%, same below) intermediate alloy ingot, Al-20Si intermediate alloy ingot, Al-10Sr intermediate alloy rod, and Al-5Ti-1B intermediate alloy rod are selected as raw materials, and are melted in a traditional resistance furnace, the degassing refining process is implemented according to the conventional process, the aluminum melt after melting is cast into a slab with a thickness of 20mm, and is cut into a plurality of high copper content aluminum silicon alloy plates with a thickness of 3mm;

[0063] (2) the high copper content aluminum silicon alloy plate is subjected to solution treatment, the solution treatment is at a temperature of 515℃ for 12h;

[0064] (3) the high copper content aluminum silicon alloy after solution treatment is quenched in 70℃ warm water for 10 minutes;

[0065] (4) the high copper content aluminum silicon alloy after quenching is subjected to friction stir processing at a rotation speed of 800 rpm, the forward speed of the stirring head used in the friction stir processing is 100 mm / min;

[0066] (5) the high copper content aluminum silicon alloy after friction stir processing is immediately aged at a temperature of 175℃ for 4h.

[0067] Example 3

[0068] The high copper content aluminum silicon alloy of the present example has the same composition and chemical components as in Example 1.

[0069] The method for deformation heat treatment of the high copper content aluminum silicon alloy of the present example comprises the following steps:

[0070] (1) According to the composition of high copper content aluminum silicon alloy, the raw materials are configured, high purity Al ingot, high purity Mg ingot and Al-50Cu (mass fraction, 50%, the same below) intermediate alloy ingot, Al-20Si intermediate alloy ingot, Al-10Sr intermediate alloy rod, Al-5Ti-1B intermediate alloy rod are selected as raw materials, and are smelted in a traditional resistance furnace, the degassing refining process is implemented according to the conventional process, the aluminum melt after smelting is cast into a slab with a thickness of 20mm, and is cut into several high copper content aluminum silicon alloy plates with a thickness of 3mm;

[0071] (2) The high copper content aluminum silicon alloy plate is subjected to solid solution treatment, and the solid solution treatment is under the condition of 515℃ temperature for 12h;

[0072] (3) The high copper content aluminum silicon alloy after solid solution treatment is quenched in warm water at 75℃ for 10min;

[0073] (4) The quenched high copper content aluminum silicon alloy is subjected to friction stir processing at a rotating speed of 1000rpm, and the forward speed of the stir head used for friction stir processing is 100mm / min;

[0074] (5) The high copper content aluminum silicon alloy after friction stir processing is immediately aged at a temperature of 175℃ for 4h.

[0075] Example 4

[0076] The weight percentage and chemical composition of the high copper content aluminum silicon alloy of the embodiment are as follows: Si: 6.90%, Cu: 2.97%, Mg: 0.51%, Sr: 0.02%, Fe: 0.10%, Ti: 0.02%, and the balance is Al and unavoidable impurities.

[0077] The method for deformation heat treatment of the high copper content aluminum silicon alloy of the embodiment comprises the following steps:

[0078] (1) According to the composition of high copper content aluminum silicon alloy, the raw materials are configured, high purity Al ingot, high purity Mg ingot and Al-50Cu (mass fraction, 50%, the same below) intermediate alloy ingot, Al-20Si intermediate alloy ingot, Al-10Sr intermediate alloy rod, Al-5Ti-1B intermediate alloy rod are selected as raw materials, and are smelted in a traditional resistance furnace, the degassing refining process is implemented according to the conventional process, the aluminum melt after smelting is cast into a slab with a thickness of 20mm, and is cut into several high copper content aluminum silicon alloy plates with a thickness of 3mm;

[0079] (2) The high copper content aluminum silicon alloy plate is subjected to solid solution treatment, and the solid solution treatment is under the condition of 495℃ temperature for 12h;

[0080] (3) The high copper content aluminum silicon alloy after solid solution treatment is quenched in warm water at 80℃ for 15min;

[0081] (4) quenching the high copper content aluminum silicon alloy at 800 rpm under friction stir processing, the advance speed of the stir head used in the friction stir processing is 100 mm / min;

[0082] (5) aging the high copper content aluminum silicon alloy immediately after the friction stir processing at 175℃ for 6h.

[0083] Example 5

[0084] The weight percentage and chemical composition of the high copper content aluminum silicon alloy of this example are the same as those of Example 4.

[0085] The method of the deformation heat treatment of the high copper content aluminum silicon alloy of this example comprises the following steps:

[0086] (1) configuring raw materials according to the composition of the high copper content aluminum silicon alloy, selecting high-purity Al ingot, high-purity Mg ingot, Al-50Cu (mass fraction, 50%, the same below) intermediate alloy ingot, Al-20Si intermediate alloy ingot, Al-10Sr intermediate alloy rod, and Al-5Ti-1B intermediate alloy rod as raw materials, melting in a traditional resistance furnace, and implementing degassing refining process according to the conventional process, casting the aluminum melt after melting into a slab with a thickness of 20 mm, and cutting into several high copper content aluminum silicon alloy plates with a thickness of 3 mm;

[0087] (2) solid solution treatment of the high copper content aluminum silicon alloy plate, the solid solution treatment is at a temperature of 525℃ for 12h;

[0088] (3) quenching the high copper content aluminum silicon alloy after solid solution treatment in 70℃ water for 10min;

[0089] (4) quenching the high copper content aluminum silicon alloy at 800 rpm under friction stir processing, the advance speed of the stir head used in the friction stir processing is 100 mm / min;

[0090] (5) aging the high copper content aluminum silicon alloy immediately after the friction stir processing at 175℃ for 4h.

[0091] Example 6

[0092] The weight percentage and chemical composition of the high copper content aluminum silicon alloy of this example are: Si: 6.97%, Cu: 2.95%, Mg: 0.48%, Sr: 0.02%, Fe: 0.08%, Ti: 0.02%, and the balance is Al and unavoidable impurities.

[0093] The method of the deformation heat treatment of the high copper content aluminum silicon alloy of this example comprises the following steps:

[0094] (1) According to the composition of high copper content aluminum silicon alloy, raw materials are configured, high purity Al ingot, high purity Mg ingot and Al-50Cu (mass fraction, 50%, the same below) intermediate alloy ingot, Al-20Si intermediate alloy ingot, Al-10Sr intermediate alloy rod, Al-5Ti-1B intermediate alloy rod are selected as raw materials, and are smelted in a traditional resistance furnace, the degassing refining process is implemented according to the conventional process, the aluminum melt after smelting is cast into a slab with a thickness of 20mm, and is cut into several high copper content aluminum silicon alloy plates with a thickness of 3mm;

[0095] (2) The high copper content aluminum silicon alloy plate is subjected to solid solution treatment, and the solid solution treatment is under the condition of 515℃ temperature for 12h;

[0096] (3) The high copper content aluminum silicon alloy after solid solution treatment is quenched in 70℃ warm water for 10min;

[0097] (4) The high copper content aluminum silicon alloy after quenching is subjected to friction stir processing at a speed of 800rpm, and the forward speed of the stir head used for friction stir processing is 100mm / min;

[0098] (5) The high copper content aluminum silicon alloy after friction stir processing is immediately aged at a temperature of 175℃ for 6h.

[0099] Example 7

[0100] The weight percentage and chemical composition of the high copper content aluminum silicon alloy of the embodiment are the same as those of example 6.

[0101] The deformation heat treatment method of the high copper content aluminum silicon alloy of the embodiment includes the following steps:

[0102] (1) According to the composition of high copper content aluminum silicon alloy, raw materials are configured, high purity Al ingot, high purity Mg ingot and Al-50Cu (mass fraction, 50%, the same below) intermediate alloy ingot, Al-20Si intermediate alloy ingot, Al-10Sr intermediate alloy rod, Al-5Ti-1B intermediate alloy rod are selected as raw materials, and are smelted in a traditional resistance furnace, the degassing refining process is implemented according to the conventional process, the aluminum melt after smelting is cast into a slab with a thickness of 20mm, and is cut into several high copper content aluminum silicon alloy plates with a thickness of 3mm;

[0103] (2) The high copper content aluminum silicon alloy plate is subjected to solid solution treatment, and the solid solution treatment is under the condition of 515℃ temperature for 12h;

[0104] (3) The high copper content aluminum silicon alloy after solid solution treatment is quenched in 70℃ warm water for 10min;

[0105] (4) quenching the high copper content Al-Si alloy after quenching at a rotational speed of 800 rpm, the forward speed of the stir head used in the friction stir processing being 100 mm / min;

[0106] (5) immediately aging the high copper content Al-Si alloy after the friction stir processing at a temperature of 175℃ for 8h.

[0107] Example 8

[0108] The high copper content Al-Si alloy of this example has the following weight percentage and chemical composition: Si: 7.2%, Cu: 3.2%, Mg: 0.45%, Sr: 0.03%, Fe: 0.14%, Ti: 0.04%, and the balance being Al and unavoidable impurities.

[0109] The method for the deformation heat treatment of the high copper content Al-Si alloy of this example includes the following steps:

[0110] (1) configuring raw materials according to the composition of the high copper content Al-Si alloy, selecting high-purity Al ingots, high-purity Mg ingots, Al-50Cu (mass fraction, 50%, same below) intermediate alloy ingots, Al-20Si intermediate alloy ingots, Al-10Sr intermediate alloy rods, and Al-5Ti-1B intermediate alloy rods as raw materials, melting in a traditional resistance furnace, and implementing degassing refining process according to the conventional process, casting the aluminum melt after melting into a slab with a thickness of 20mm, and cutting into several high copper content Al-Si alloy plates with a thickness of 3mm;

[0111] (2) solid solution treatment of the high copper content Al-Si alloy plate, the solid solution treatment being at a temperature of 515℃ for 14h;

[0112] (3) quenching the high copper content Al-Si alloy after solid solution treatment in 80℃ warm water for 10min;

[0113] (4) quenching the high copper content Al-Si alloy after quenching at a rotational speed of 800 rpm, the forward speed of the stir head used in the friction stir processing being 120 mm / min;

[0114] (5) immediately aging the high copper content Al-Si alloy after the friction stir processing at a temperature of 180℃ for 6h.

[0115] Comparative Example 1

[0116] The high copper content Al-Si alloy selected in this comparative example has the same weight percentage and chemical composition as Example 1, and the method for the deformation heat treatment of the high copper content Al-Si alloy in this comparative example includes the following steps:

[0117] (1) high copper content Al-Si alloy is solid solution treated, the solid solution is at 495℃ temperature condition for 12h;

[0118] (2) high copper content Al-Si alloy after solid solution treatment is quenched in 70℃ warm water;

[0119] (3) high copper content Al-Si alloy after quenching is immediately aged at 175℃ temperature condition for 4h.

[0120] Comparative Example 2

[0121] The high copper content Al-Si alloy selected in the present comparative example has the same composition and chemical components as in Example 1, and the deformation heat treatment method of the high copper content Al-Si alloy in the present comparative example comprises the following steps:

[0122] (1) high copper content Al-Si alloy is solid solution treated, the solid solution is at 515℃ temperature condition for 12h;

[0123] (2) high copper content Al-Si alloy after solid solution treatment is quenched in 80℃ warm water;

[0124] (3) high copper content Al-Si alloy after quenching is immediately aged at 180℃ temperature condition for 4h.

[0125] Comparative Example 3

[0126] The high copper content Al-Si alloy selected in the present comparative example has the same composition and chemical components as in Example 1, and the deformation heat treatment method of the high copper content Al-Si alloy in the present comparative example comprises the following steps:

[0127] The alloys after the treatment in the above-mentioned Examples 1-8 and Comparative Examples 1-3 are subjected to performance detection, and the details are shown in Table 1.

[0128] Table 1 Performance indexes of the alloys after the treatment in Examples 1-8 and Comparative Examples 1-3

[0129]

[0130]

[0131] As can be seen from Table 1, the tensile strength of the high copper content Al-Si alloy in Examples 1-8 is in the range of 410-431MPa, the yield strength is in the range of 339-366MPa, and the elongation is in the range of 9.4%-13.2%; while the alloys in the comparative examples after heat treatment or friction stirring treatment cannot have both strength and toughness; thus, it can be seen that the high copper content Al-Si alloy in the present application after deformation heat treatment realizes the synergistic improvement of the strength and toughness of the high copper content Al-Si alloy.

[0132] Combination Figure 2 As shown in (a), the microstructure of the alloy of Comparative Example 1 after solid solution treatment at 495℃ for 12h, (b) is the microstructure of the alloy of Comparative Example 2 after solid solution treatment at 515℃ for 12h, (c) is the microstructure of the alloy of Example 2 after deformation heat treatment, in which, the grayish white is the aluminum matrix, the gray is the eutectic silicon particles, and the brown is the hole defects produced by the melting of Q phase; in combination with Figure 2 As shown in (a), the microstructure of the alloy of Comparative Example 1 after solid solution treatment at 495℃ for 12h, (b) is the microstructure of the alloy of Comparative Example 2 after solid solution treatment at 515℃ for 12h, (c) is the microstructure of the alloy of Example 2 after deformation heat treatment, in which, the grayish white is the aluminum matrix, the gray is the eutectic silicon particles, and the brown is the hole defects produced by the melting of Q phase; in combination with Figure 2 As shown in (b), the microstructure of the alloy of Comparative Example 2 after solid solution treatment at 515℃ for 12h, in which, the eutectic silicon particles have a size of about 3.8μm, the residual Q phase has a size of ≤3.4μm, and the hole defects produced by the melting of Q phase have a size of about 17.2μm-20.2μm, and the area ratio of the hole defects is about 0.8%; in combination with Figure 2 As shown in (c), the microstructure of the alloy of Example 2, in which, the eutectic silicon particles have a size of 2.1-2.8μm, and the area ratio of the eutectic silicon particles in the alloy is 7.3-7.8%; the residual Q phase has a size of ≤2.6μm, and the area ratio of the residual Q phase in the alloy is ≤0.8%; since the hole defects produced by the melting of Q phase are welded by the friction stir processing in Example 2, the size of the hole defects produced by the melting of Q phase is <1μm, and the area ratio is close to 0.

[0133] Figure 3 As shown in the DSC graph of the alloy of Comparative Example 1, it can be seen that the Q phase will melt at about 506℃, which is the reason why the hole defects will be produced when the high-copper-content aluminum-silicon alloy is solid-solution-treated at a temperature higher than 510℃; the eutectic silicon will be broken and spheroidized very slowly when the solid solution is carried out at a temperature lower than 510℃, which is not conducive to the application in the industrial production process; these hole defects produced by the solid solution will be significantly eliminated in the friction stir processing.

[0134] Figure 4 As shown in the DSC graph of the alloy of Comparative Example 1, it can be seen that the Q phase will melt at about 506℃, which is the reason why the hole defects will be produced when the high-copper-content aluminum-silicon alloy is solid-solution-treated at a temperature higher than 510℃; the eutectic silicon will be broken and spheroidized very slowly when the solid solution is carried out at a temperature lower than 510℃, which is not conducive to the application in the industrial production process; these hole defects produced by the solid solution will be significantly eliminated in the friction stir processing.

[0135] In summary, the method for thermo-mechanical treatment of the present application eliminates some hole defects formed by partial overburning of Q phase in high temperature solid solution process through friction stir processing, promotes full solid solution of Q phase and full spheroidization of silicon particles, further refines the microstructure of the alloy, and effectively solves the contradiction between fine spheroidization of eutectic silicon and dissolution of copper-containing phase in the traditional T6 treatment process.

[0136] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present application, and are not used as a limitation to the present application, and as long as the changes and modifications of the above described embodiments are within the spirit and principles of the present application, they will fall within the scope of the claims of the present application.

Claims

1. A high-copper-content aluminum-silicon alloy, characterized by, The alloy comprises the following ingredients by weight percentage: Si: 6.8-7.2%, Cu: 2.8-3.2%, Mg: 0.45-0.55%, Sr: 0.02-0.04%, Ti: 0.02-0.04%, Fe < 0.15%, and the balance of Al and inevitable impurities.

2. The high-copper-content Al-Si alloy according to claim 1, characterized in that, The microstructure of the high-copper-content aluminum-silicon alloy comprises eutectic silicon particles and residual Q phase.

3. The high-copper-content Al-Si alloy according to claim 2, characterized in that, The size of the eutectic silicon particles is ≤2.8 μm, and the area percentage of the eutectic silicon particles in the alloy is ≤7.8%; and / or The size of the residual Q phase is ≤2.6 μm, and the area percentage of the residual Q phase in the alloy is ≤0.8%.

4. The high-copper-content Al-Si alloy according to claim 1, characterized in that, The performance satisfies: the tensile strength is above 400 MPa, the yield strength is above 320 MPa, and the elongation is above 9%.

5. A method of thermomechanical treatment of high-copper aluminum-silicon alloys as claimed in any one of claims 1 to 4, characterized in that, The method comprises the following steps: S1, preparing a high-copper-content aluminum-silicon alloy plate according to the composition of the high-copper-content aluminum-silicon alloy; S2, subjecting the high-copper-content aluminum-silicon alloy plate to solid solution treatment at 495-525 ℃, and then to quenching treatment; S3, subjecting the quenched high-copper-content aluminum-silicon alloy plate to stir friction treatment at a rotating speed of 600-1000 rpm; S4, subjecting the high-copper-content aluminum-silicon alloy plate after the stir friction treatment to aging treatment.

6. The method of thermomechanical treatment of high-copper aluminum-silicon alloys according to claim 5, characterized in that, In the step S1, the raw materials for preparing the high-copper-content aluminum-silicon alloy plate are high-purity Al, high-purity Mg, Al-Cu intermediate alloy, Al-Si intermediate alloy, Al-Sr intermediate alloy, and Al-Ti-B intermediate alloy.

7. The method of thermomechanical treatment of high-copper aluminum silicon alloy according to claim 6, characterized in that, In the step S1, when preparing the high-copper-content aluminum-silicon alloy plate, the raw materials are melted into an aluminum melt, then cast into a slab, and the slab is cut into a high-copper-content aluminum-silicon alloy plate with a thickness of ≤3 mm.

8. The method of thermomechanical treatment of high-copper aluminum-silicon alloys according to claim 5, characterized in that, In the step S2, the solid solution treatment time is 12-14 h.

9. The method of thermomechanical treatment of high-copper aluminum silicon alloy according to claim 5, wherein The time interval between the step S2 and the step S3 is not more than 1 h.

10. The method of thermomechanical treatment of high-copper aluminum-silicon alloys according to claim 5, characterized in that, In the step S2, the quenching treatment is quenching the high-copper-content aluminum-silicon alloy plate after the solid solution treatment in warm water at 70-80 ℃, and the quenching treatment time is 10-15 min.

11. The method of thermomechanical treatment of high-copper aluminum-silicon alloy according to claim 5, wherein In the step S3, the forward speed of the stir head used for the stir friction treatment is 100-120 mm / min.

12. The method of thermomechanical treatment of high-copper aluminum-silicon alloys according to claim 5, characterized in that, In the step S4, in the aging treatment, the aging temperature is 175-180 ℃, and the treatment time is 4-8 h.

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