Metal type gravity casting high-strength aluminum alloy and preparation method thereof

Abstract

The invention relates to the technical field of aluminum alloy materials, and solves the problems that a ZL205 material is large in hot cracking tendency, poor in casting fluidity and the like and cannot be suitable for a metal mold gravity casting process. The invention discloses a metal type gravity casting high-strength aluminum alloy and a preparation method thereof. The metal type gravity casting high-strength aluminum alloy is composed of, by weight, 5.0%-7.0% of Si, 4.5%-5.5% of Cu, 0.3%-0.5% of Mn, 0.05%-0.15% of V, 0.10%-0.20% of Ti, 0.05%-0.15% of Zr, smaller than or equal to 0.2% of Fe, larger than or equal to 0.0040% of P and the balance Al. The high-strength aluminum alloy prepared by adopting the preparation method of the metal mold gravity casting aluminum alloy can reach the conditions that the normal-temperature tensile strength is greater than or equal to 420MPa, the elongation is greater than or equal to 1%, and the forming is good.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy materials, and in particular to a metal mold gravity casting high-strength aluminum alloy and a preparation method thereof. Background Art

[0002] Aluminum and aluminum alloys have many excellent properties such as light weight, corrosion resistance, easy formability, high specific strength, high electrical and thermal conductivity, and easy recycling. Therefore, they are widely used in various industries such as construction, automobiles, aircraft, ships, and defense industry. At present, certain products require room temperature tensile strength ≥400MPa and elongation ≥1%. The production cost of high-strength forged aluminum alloy is relatively high. In order to save costs, the metal mold gravity casting process is prepared, and it is urgent to develop a metal mold gravity casting high-strength aluminum alloy preparation and strengthening method.

[0003] The aluminum alloys suitable for metal mold gravity casting mainly include ZL101A, ZL114A, ZL108, ZL10, etc. The tensile strength of ZL101A is ≥295, and the elongation is ≥3%; the tensile strength of ZL114 is ≥310, and the elongation is ≥3%; the tensile strength of ZL108 is ≥255, and the elongation is ≥0.5%; the tensile strength of ZL109 is ≥195, and the elongation is ≥0.5%. The above materials cannot meet the use of high-strength products.

[0004] China has developed high-strength cast aluminum alloys such as ZL205, which belong to the aluminum-copper-manganese system and have material properties that can meet the requirements of this type of product. However, ZL205 has problems such as a high tendency to hot cracking and poor casting fluidity, making it unsuitable for metal mold gravity casting processes. Summary of the invention

[0005] The purpose of the present invention is to provide a metal mold gravity casting high-strength aluminum alloy and a preparation method to solve the problems of the ZL205 material in the prior art, such as a large tendency to thermal cracking, poor casting fluidity, and the inability to be applied to the metal mold gravity casting process.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The invention provides a metal mold gravity casting high-strength aluminum alloy, which consists of the following components in weight percentage: Si: 5.0-7.0%, Cu: 4.5-5.5%, Mn: 0.3-0.5%, V: 0.05-0.15%, Ti: 0.10-0.20%, Zr: 0.05-0.15%, Fe≤0.2%, P≥0.0040%, and Al balance.

[0008] The present invention also provides a method for preparing a high-strength aluminum alloy by metal mold gravity casting, comprising the following steps:

[0009] S1. Aluminum alloy material smelting: first add silicon to the bottom of the industrial frequency furnace, then pour the melted aluminum liquid in the natural gas continuous melting furnace, then add copper and manganese, turn on the industrial frequency furnace to heat up, and when the aluminum liquid temperature reaches 780℃±20℃, add aluminum vanadium alloy, aluminum titanium alloy, aluminum zirconium alloy, and aluminum phosphorus alloy, continue to heat up for insulation diffusion smelting, take samples of the components, and after the components are qualified, perform water discharge operation;

[0010] S2. Aluminum liquid refining:

[0011] S21. Pretreatment of aluminum liquid for Ca removal: at 770-790℃, the speed of the degasser is controlled at 480-520 rpm, the gas pressure is controlled at 0.5-0.6MPa, and the gas flow rate is controlled at 5-15L / min, a certain amount of Ca removal flux is rotated for degassing for 5 minutes;

[0012] S22, aluminum liquid refining treatment: Pyroflux GR DR212 refining agent is poured into the aluminum liquid vortex along the vortex edge for refining treatment, and the aluminum liquid is refined and degassed for 10 minutes;

[0013] S23, aluminum liquid standing: After aluminum liquid is refined, stand it for 10 minutes, and use density equivalent instrument to detect aluminum liquid quality. Only when density equivalent DI value is ≤0.6, can slag be cleaned and ladle be opened for pouring;

[0014] S3. Heat treatment: subjecting the aluminum alloy piston to solid solution and aging treatment.

[0015] Furthermore, the specific conditions of the heat preservation diffusion smelting in S1 are 900-930° C., and the heat preservation diffusion time is 20-40 minutes.

[0016] Furthermore, the method of adding the Ca-removing flux in S21 is as follows: the degasser rotor is placed in the center of the aluminum liquid container and rotated, and after the aluminum liquid forms a relatively large vortex, a certain amount of the Ca-removing flux is poured into the aluminum liquid vortex along the edge of the vortex.

[0017] Furthermore, the amount of the Ca-removing flux added is as follows:

[0018] Ca control range (%) FUSAL 1956 Ca removal flux addition amount Ca content in aluminum liquid after pretreatment (%) As:<0.004 80g ≤0.001 Ca: 0.004~0.006 120g ≤0.001 Ca:>0.006 160g ≤0.001 .

[0019] Furthermore, the refining temperature in S22 is 770-790° C., and the refining agent is 60-90 g.

[0020] Furthermore, the solution treatment in S3 is: 510°C×2 hours, quenching water temperature is 60-90°C, and furnace entry time is ≤15 seconds; aging treatment is: 180°C×5h, furnace entry temperature is ≤50°C, and heating time is ≥45 minutes.

[0021] Key points, highlights and corresponding mechanisms of each process of the present invention:

[0022] 1. Alloy composition selection: ① Select Cu: 4.5-5.5%, Mn: 0.3-0.5%, mainly to utilize the good strengthening and hardening effects of Cu, Mg, and Ni in this range to improve the mechanical strength of the piston. ② Select Si: 5.0-7.0%, Fe≤0.2%, which can ensure the elongation of aluminum alloy materials. ③ Add trace elements such as V, Ti, and Zr to Al-Si alloys. Trace elements such as V, Ti, and Zr can refine the cast structure and inhibit the growth of grains during the recrystallization process of the alloy, which can improve the tensile strength and plasticity of the alloy. ④: Aluminum alloys containing 5.0-7.0% Si belong to hypoeutectic components. Na or Sr modification is conventionally used, but Na modification has an onset time of less than 1 hour, which seriously corrodes the crucible. Sr modification is prone to pore defects, while material P modification achieves long-term modification. A small amount of primary silicon structure appears in the hypoeutectic composition, making the performance of the aluminum alloy stable.

[0023] 2. Alloy smelting process: In this process, aluminum-phosphorus alloy modifier is added, and the high temperature is 900-930℃, and the duration is 20-40 minutes to maintain the diffusion smelting. The alloy homogenization effect is good, and the content of free P element is mainly increased. Free P plays a role in inhibiting the growth of silicon phase and promoting the refinement of primary silicon. Hypoeutectic aluminum silicon adopts P modification process, by adding aluminum-phosphorus alloy modifier, adding temperature 900-930℃, and maintaining the diffusion smelting for 20-40 minutes.

[0024] 3. Aluminum liquid refining process: On-site aluminum liquid Ca removal pretreatment and control of the amount of Ca removal flux added: When the Ca content in the melt increases, it is easy to form AlCa compounds with high melting points, which reduce the fluidity and shrinkage compensation performance of the aluminum alloy. At the same time, it may also form a compound phase (such as Al4Ca) that is insoluble in the aluminum matrix, thereby affecting the performance of the aluminum alloy after heat treatment; excess Ca can also react with Al and Si to form coarse plate-like Al2Si2Ca phases; and the presence of Ca will also cause the rupture of the Al2O3 oxide film, increase the hydrogen content of the aluminum liquid and the probability of pores and looseness in the castings, affecting the surface and internal quality of the product. According to research, the lower the Ca content in the alloy, the more significant the P modification effect, and the smaller the average size of the primary silicon crystal. According to the Ca content in the aluminum liquid, add the corresponding Ca removal flux. When Ca≤0.001% and ≥0.006%, the aluminum liquid modification effect is best.

[0025] 4. Heat treatment aging process: Solution treatment, 510℃×2 hours, quenching water temperature 60-90℃, furnace time ≤15 seconds, aging treatment, 180℃×5h, to improve the aging strengthening effect and hardness of Al-Si alloy piston, and improve the comprehensive mechanical properties of aluminum alloy blank.

[0026] Based on the above technical solution, the embodiments of the present invention can at least produce the following technical effects:

[0027] The high-strength aluminum alloy prepared by the metal mold gravity casting aluminum alloy preparation method of the present invention can achieve: room temperature tensile strength ≥420MPa, elongation ≥1%, and good forming. DETAILED DESCRIPTION

[0028] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0029] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0030] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0031] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0033] Pyroflux GR DR212 refining agent and FUSAL 1956 Ca removal flux are purchased from Perico

[0034] According to the aluminum alloy composition control requirements, 3 furnaces of aluminum liquid alloy are prepared, each furnace is prepared with 300Kg. The aluminum liquid alloy is smelted according to the aluminum alloy material smelting process requirements, and the alloy composition is tested in each furnace.

[0035] Si: 5.0-7.0%, Cu: 4.5-5.5%, Mn: 0.3-0.5%, V: 0.05-0.15%, Ti: 0.10-0.20%, Zr 0.05-0.15%, Fe≤0.2%, P≥0.0040%

[0036] Example 1

[0037] The aluminum liquid refining process is as follows:

[0038] a) On-site aluminum liquid Ca removal pretreatment: The aluminum liquid temperature of the on-site holding furnace was detected to be 785°C, 80g FUSAL 1956 Ca removal flux was added, and the mixture was rotated for degassing for 5 minutes;

[0039] b) Aluminum liquid refining treatment: The aluminum liquid temperature after pretreatment was detected to be 776°C, and 65g of Pyroflux GRDR212 refining agent was added for refining and degassing treatment for 10 minutes;

[0040] c) Let the aluminum liquid stand: After the aluminum liquid is refined, let it stand for 10 minutes. The density equivalent meter detects that the aluminum liquid density equivalent DI value is 0.3.

[0041] d) Composition detection: After the aluminum liquid is refined, a composition sample is taken to detect the piston composition. The composition of each component of the aluminum liquid alloy is as follows:

[0042] Si 5.22%, Cu 4.84%, Mn 0.43%, V 0.085%, Ti 0.14%, Zr 0.08%, Fe 0.18%, P 0.0053%, and the rest is Al.

[0043] e) Using a special metal gravity casting mold, the pouring temperature is 760-780℃, and 20 blanks are cast, and the forming is good.

[0044] Example 2

[0045] The aluminum liquid refining process is as follows:

[0046] a) On-site aluminum liquid Ca removal pretreatment: The aluminum liquid temperature of the on-site holding furnace was detected to be 788°C, 160g FUSAL 1956 Ca removal flux was added, and the mixture was rotated for degassing for 5 minutes;

[0047] b) Aluminum liquid refining treatment: The temperature of the aluminum liquid after pretreatment was detected to be 778°C, and 70g of Pyroflux GRDR212 refining agent was added for refining and degassing treatment for 10 minutes;

[0048] c) Let the aluminum liquid stand: After the aluminum liquid is refined, let it stand for 10 minutes. The density equivalent meter detects that the aluminum liquid density equivalent DI value is 0.2.

[0049] d) Composition detection: After the aluminum liquid is refined, a composition sample is taken to detect the piston composition. The composition of each component of the aluminum liquid alloy is as follows:

[0050] Si 6.21%, Cu 4.95%, Mn 0.35%, V 0.075%, Ti 0.16%, Zr 0.09%, Fe 0.16%, P 0.0108%, Ca 0.0068%, and the rest is Al.

[0051] e) Using a special metal gravity casting mold, the pouring temperature is 760-780℃, and 20 blanks are cast, and the forming is good.

[0052] Example 3

[0053] The aluminum liquid refining process is as follows:

[0054] a) On-site aluminum liquid Ca removal pretreatment: The aluminum liquid temperature of the on-site holding furnace was detected to be 784°C, 120g FUSAL 1956 Ca removal flux was added, and the mixture was rotated for degassing for 5 minutes;

[0055] b) Aluminum liquid refining treatment: The aluminum liquid temperature after pretreatment was detected to be 775°C, and 85g of Pyroflux GRDR212 refining agent was added for refining and degassing treatment for 10 minutes;

[0056] c) Let the aluminum liquid stand: After the aluminum liquid is refined, let it stand for 10 minutes. The density equivalent meter detects that the aluminum liquid density equivalent DI value is 0.3.

[0057] d) Composition detection: After the aluminum liquid is refined, a composition sample is taken to detect the piston composition. The composition of each component of the aluminum liquid alloy is as follows:

[0058] Si 6.78%, Cu 5.21%, Mn 0.45%, V 0.088%, Ti 0.12%, Zr 0.10%, Fe 0.18%, P 0.0072%, and the rest is Al.

[0059] e) Using a special metal gravity casting mold, the pouring temperature is 760-780℃, and 20 blanks are cast, and the forming is good.

[0060] Heat treatment of blank:

[0061] The blanks of Examples 1-3 were processed in the same batch, with a vertical quenching furnace used for the solution treatment and a box-type resistance furnace used for the aging treatment.

[0062] Extraction performance:

[0063] The performance test data is as follows:

[0064]

[0065] The test data in the above table show that the high-strength aluminum alloy produced by the metal mold gravity casting process can achieve: room temperature tensile strength ≥420MPa, elongation ≥1%, and good forming.

[0066] Finally, it should be noted that:

[0067] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A metal mold gravity casting high-strength aluminum alloy, characterized in that: It is composed of the following components in weight percentage: Si: 5.0-7.0%, Cu: 4.5-5.5%, Mn: 0.3-0.5%, V: 0.05-0.15%, Ti: 0.10-0.20%, Zr: 0.05-0.15%, Fe≤0.2%, P≥0.0040%, and Al balance.

2. The method for preparing a high-strength aluminum alloy by metal mold gravity casting according to claim 1, characterized in that: The following steps are involved: S1. Melting of aluminum alloy materials: first add silicon, then pour in the molten aluminum, then add copper and manganese, start the industrial frequency furnace to heat up, and when the aluminum liquid temperature reaches 780℃±20℃, add aluminum-vanadium alloy, aluminum-titanium alloy, aluminum-zirconium alloy, and aluminum-phosphorus alloy, and continue to heat up for insulation diffusion melting; S2. Aluminum liquid refining: S21. Pretreatment of aluminum liquid for Ca removal: at 770-790℃, the speed of the degasser is controlled at 480-520 rpm, the gas pressure is controlled at 0.5-0.6MPa, and the gas flow rate is controlled at 5-15L / min, a certain amount of Ca removal flux is rotated for degassing for 5 minutes; S22, aluminum liquid refining treatment: after adding the refining agent, the aluminum liquid is refined and degassed for 10 minutes; S23, aluminum liquid standing: After aluminum liquid is refined, stand it for 10 minutes, and use density equivalent instrument to test aluminum liquid quality. Only when density equivalent DI value is ≤0.6, can slag be cleaned and ladle be opened for pouring; S3. Heat treatment: subjecting the aluminum alloy piston to solid solution and aging treatment.

3. The method for preparing a high-strength aluminum alloy by metal mold gravity casting according to claim 2, characterized in that: The specific conditions of the heat preservation diffusion smelting in S1 are 900-930° C. and the heat preservation diffusion time is 20-40 minutes.

4. The method for preparing a high-strength aluminum alloy by metal mold gravity casting according to claim 2, characterized in that: The method of adding the Ca-removing flux in S21 is as follows: the degasser rotor is placed in the center of the aluminum liquid container and rotated, and after the aluminum liquid forms a relatively large vortex, a certain amount of Ca-removing flux is poured into the aluminum liquid vortex along the edge of the vortex.

5. The method for preparing a high-strength aluminum alloy by metal mold gravity casting according to claim 4, characterized in that: The amount of Ca-removing flux added is related to the Ca% control range. When Ca<0.004%, the Ca-removing flux is 80g; Ca: When 0.004%-0.006%, remove the Ca flux of 120g; when Ca>0.006%, remove the Ca flux of 160g.

6. The method for preparing a high-strength aluminum alloy by metal mold gravity casting according to claim 2, characterized in that: The refining temperature in S22 is 770-790° C., and the refining agent is 60-90 g.

7. The method for preparing a high-strength aluminum alloy by metal mold gravity casting according to claim 2, characterized in that: The solution treatment in S3 is carried out at 510°C for 2 hours, the quenching water temperature is 60-90°C, and the furnace entry time is ≤15 seconds; the aging treatment is carried out at 180°C for 5 hours, the furnace entry temperature is ≤50°C, and the heating time is ≥45 minutes.

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