Cast aluminum alloy and preparation method thereof
By controlling the cooling rate and Mn mass fraction of cast aluminum alloys and combining them with specific heat treatment processes, the problem of decreased mechanical properties caused by coarse second phases was solved, thus improving the performance and expanding the applications of cast aluminum alloys.
Patent Information
- Application Number
- CN202511635698.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-10
- Publication Date
- 2026-02-27
AI Technical Summary
In traditional cast aluminum alloys, coarse second phases are easily formed, which leads to a decrease in material elongation and an increase in the scrap rate of plastic forming, affecting its mechanical properties and application scenarios.
By controlling the cooling rate and Mn mass fraction of the cast aluminum alloy, the formation of coarse second phase is suppressed. Specific heat treatment processes, such as solution treatment, water quenching treatment, and aging treatment, are used to ensure uniform distribution of solute atoms and refine the phase structure.
It effectively inhibits the formation of coarse second phases, improves the mechanical properties of cast aluminum alloys, and expands their high-end application scenarios.
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Figure CN121575253A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of metal materials, in particular to a cast aluminum alloy and a preparation method thereof. BACKGROUND
[0002] The cast aluminum alloy is widely used in the fields of automobile manufacturing (chassis and engine parts), aerospace (lightweight structural parts), electronic heat dissipation (radiator shell) and marine engineering (corrosion-resistant components) due to its low density, excellent cast fluidity, good corrosion resistance and thermal and electrical conductivity.
[0003] Among them, the mechanical properties such as tensile strength and elongation of the cast aluminum alloy are closely related to the size of the second phase in the cast aluminum alloy. Coarse second phases are easily formed in traditional cast aluminum alloys. Such phase particles can destroy the continuity of the matrix and cause stress concentration, resulting in a decrease of 15% to 30% in the elongation of the material. At the same time, the coarse second phase also hinders the movement of dislocations and increases the work hardening tendency, which increases the scrap rate of subsequent plastic forming. Therefore, reducing the size of the second phase is crucial to improve the comprehensive performance of the cast aluminum alloy and expand its high-end application scenarios. SUMMARY
[0004] Based on this, the present application provides a cast aluminum alloy and a preparation method thereof. The preparation method of the cast aluminum alloy provided by the present application regulates the mass fraction of Mn in the cast aluminum alloy according to different cooling rates, which can inhibit the formation of coarse second phases and further improve the mechanical properties of the cast aluminum alloy.
[0005] In a first aspect, the present application provides a preparation method of a cast aluminum alloy, comprising the following steps:
[0006] After preparing raw materials, melting and casting according to the chemical composition of the cast aluminum alloy, a cast ingot is prepared; the cooling rate in the casting step is 0.1 ℃ / s to 20 ℃ / s or 50 ℃ / s to 100 ℃ / s;
[0007] The cast ingot is subjected to heat treatment to prepare a cast aluminum alloy.
[0008] The corresponding relationship between the cooling rate in the casting step and the mass fraction of Mn in the chemical composition of the cast aluminum alloy satisfies one of the following characteristics:
[0009] (1) The cooling rate is 0.1 ℃ / s to 20 ℃ / s, and the mass fraction of Mn in the chemical composition of the cast aluminum alloy is 0.1% to 0.23%;
[0010] (2) The cooling rate is 50 ℃ / s to 100 ℃ / s, and the mass fraction of Mn in the cast aluminum alloy is 0.25% to 0.35%.
[0011] In some embodiments, the chemical composition of the cast aluminum alloy further comprises: Cr, 0.07% to 0.1% by mass.
[0012] In some embodiments, the chemical composition of the cast aluminum alloy further comprises: Al, 80% to 92.43% by mass; Fe, 0.05% to 0.2% by mass; Si, 6% to 8% by mass; Cu, 1% to 2.5% by mass; Mg, 0.4% to 0.5% by mass; Zr, 0.06% to 0.12% by mass; Ti, 0.05% to 0.1% by mass; and Sr, 0.01% to 0.3% by mass.
[0013] In some embodiments, the casting is performed by metal mold gravity casting or differential pressure casting.
[0014] In some embodiments, the step of heat treating the ingot comprises:
[0015] The ingot is sequentially subjected to solid solution treatment, water quenching treatment, and aging treatment.
[0016] In some embodiments, the step of solid solution treatment comprises:
[0017] The ingot is heated from room temperature to 250°C to 350°C at a heating rate of 150°C / h to 220°C / h for first-stage holding treatment;
[0018] The temperature is raised to 480°C to 510°C at a heating rate of 150°C / h to 220°C / h for second-stage holding treatment;
[0019] The temperature is raised to 520°C to 550°C at a heating rate of 150°C / h to 220°C / h for third-stage holding treatment.
[0020] In some embodiments, the step of solid solution treatment comprises:
[0021] The first-stage holding treatment is performed for 4h to 8h;
[0022] And / or, the second-stage holding treatment is performed for 2h to 6h;
[0023] And / or, the third-stage holding treatment is performed for 2h to 6h.
[0024] In some embodiments, the water quenching treatment is performed at a temperature of 20°C to 60°C.
[0025] In some embodiments, the step of aging treatment comprises:
[0026] The intermediate after water quenching treatment is heated to 150°C to 200°C at a heating rate of 160°C / h to 200°C / h for holding treatment.
[0027] In a second aspect, the application provides a cast aluminum alloy prepared by the method of any one of the first aspect, wherein the second phase size of the cast aluminum alloy is less than or equal to 15 microns.
[0028] The method for preparing the cast aluminum alloy provided by the application has at least the following advantages:
[0029] The method for preparing the cast aluminum alloy provided by the application controls the mass fraction of Mn in the cast aluminum alloy according to different cooling rates. When the cooling rate is 0.1-20 ℃ / s, a lower Mn content has a higher solid solubility in the aluminum matrix, which can avoid the enrichment of Mn between dendrites. Therefore, the synergy of the cooling rate and Mn element can avoid the formation of coarse α-Al(Fe, Mn)Si phase. At a higher cooling rate, the ingot solidifies rapidly, which can avoid the local enrichment of Mn element to form coarse phase. At the same time, a specific Mn content can more fully form stable intermetallic compounds with Fe element in the cast aluminum alloy, thereby neutralizing the Fe element and inhibiting the generation of coarse α-Al(Fe, Mn)Si phase.
[0030] The method for preparing the cast aluminum alloy provided by the application controls the mass fraction of Mn in the cast aluminum alloy according to different cooling rates, which can inhibit the formation of coarse phase and further improve the mechanical properties of the cast aluminum alloy. BRIEF DESCRIPTION OF DRAWINGS
[0031] Figure 1 The alloy microstructure diagram of the cast aluminum alloy prepared for Example 1.
[0032] Figure 2 The alloy microstructure diagram of the cast aluminum alloy prepared for Example 2.
[0033] Figure 3 The alloy microstructure diagram of the cast aluminum alloy prepared for Comparative Example 1.
[0034] Figure 4 The statistical diagram of the second phase size in the cast aluminum alloy prepared for Example 1 and Comparative Example 1.
[0035] Figure 5 The mechanical property comparison diagram of the cast aluminum alloy prepared for Example 1 and Comparative Example 1. DETAILED DESCRIPTION
[0036] The cast aluminum alloy and the method for preparing the same provided by the application will be further and completely described below in combination with specific embodiments. The application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the application more thorough and comprehensive.
[0037] In the present application, "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise specifically limited.
[0038] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Further, when the range refers to integers, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.
[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the specification of the present application is only for the purpose of describing specific embodiments and is not intended to limit the present application. Unless otherwise stated or contradictory, the terms or phrases used herein have the following meanings:
[0040] In the present application, "multiple", "multiple", "multiple", "multiple" and the like are not specifically limited, and refer to more than two or equal to two in number. For example, "one or more" means one or more than two.
[0041] In the present application, in the terms "first aspect", "second aspect", "third aspect", "fourth aspect" and the like, the terms "first", "second", "third", "fourth" and the like are only for the purpose of description, and cannot be understood as indicating or implying relative importance or quantity, nor can it be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth" and the like only serve the purpose of non-exhaustive enumeration and description, and should be understood as not constituting a closed limitation on the number.
[0042] In the present application, the technical features described in an open manner include both closed technical solutions consisting of listed features and open technical solutions including listed features.
[0043] In the present application, "combination thereof", "any combination thereof", "any combination thereof" and the like include all suitable combinations of any two or more of the listed items.
[0044] In the present application, the "suitable" in "suitable combination", "suitable manner", "any suitable manner" and the like is subject to the ability to implement the technical solutions of the present application, solve the technical problems of the present application, and achieve the intended technical effects of the present application.
[0045] In the present application, "preferably", "more preferably", "more preferably", "preferably" only describe the better effect of the implementation mode or embodiment, and it should be understood that it does not constitute a limitation on the protection scope of the present application.
[0046] In the present application, "further", "further", "in particular" and the like are used for description purposes, indicating differences in content, but should not be understood as a limitation on the protection scope of the present application.
[0047] In the present application, "optionally", "optional", "optional" means optional, that is, selected from any one of the two parallel schemes of "yes" or "no". If there are multiple "optional" in a technical solution, unless otherwise specified, and there is no contradictory relationship or mutual restriction, each "optional" is independent.
[0048] In the present application, the numerical interval (i.e. the numerical range) is not specified, and the optional numerical distribution within the above numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e. the minimum value and the maximum value) of the numerical range, and each numerical value between the two numerical endpoints. If not specified, when the numerical interval only refers to the integers within the numerical interval, including the two endpoint integers of the numerical range and each integer between the two endpoints, in this document, it is equivalent to directly listing each integer, such as t is an integer selected from 1-10, which means t is any one integer selected from the integer group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. In addition, when multiple ranges are provided to describe characteristics or properties, these ranges can be combined. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.
[0049] The temperature parameter in the present application, unless otherwise specified, allows constant temperature treatment and allows variation within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. It is allowed to fluctuate within the range of, for example, ±5°C, ±4°C, ±3°C, ±2°C, ±1°C.
[0050] In the present application, the percentage content, unless otherwise specified, refers to mass percentage for solid-liquid mixing and solid-solid mixing, and refers to volume percentage for liquid-liquid mixing.
[0051] In the present application, the percentage concentration refers to the final concentration, unless otherwise specified. The final concentration refers to the proportion of the added component in the system after the component is added.
[0052] In a first aspect of the present application, a preparation method of a cast aluminum alloy is provided, comprising the following steps:
[0053] After preparing raw materials, smelting and casting according to the chemical composition of the cast aluminum alloy, a cast ingot is prepared; the cooling rate in the casting step is 0.1 ℃ / s-20 ℃ / s or 50 ℃ / s-100 ℃ / s.
[0054] The cast ingot is subjected to heat treatment to prepare the cast aluminum alloy.
[0055] The corresponding relationship between the cooling rate in the casting step and the mass fraction of Mn in the chemical composition of the cast aluminum alloy satisfies that the cooling rate is 0.1 ℃ / s-20 ℃ / s, and the mass fraction of Mn in the cast aluminum alloy is 0.1%-0.23%.
[0056] Further exemplarily, the present application finds that the cooling rate V c is 0.1 ℃ / s-20 ℃ / s, and the mass fraction M (Mn，%) of Mn in the cast aluminum alloy satisfies the linear relationship with the cooling rate V c . Exemplarily, a linear equation can be constructed with the cooling rate V c as the horizontal coordinate and the mass fraction M (Mn，%) of Mn in the cast aluminum alloy as the vertical coordinate, so that the cooling rate V c and the mass fraction M (Mn，%) of Mn in the cast aluminum alloy are one-to-one corresponding. Exemplarily, the linear equation is M (Mn，%) =k1×V c +b1. k1 is 0.001-0.002. b1 is 0.18-0.19. Further exemplarily, k1 is 0.00125. b1 is 0.1875. That is, M (Mn，%) =0.00125×V c +0.1875.
[0057] The corresponding relationship between the cooling rate in the casting step and the mass fraction of Mn in the cast aluminum alloy satisfies that the cooling rate is 50 ℃ / s-100 ℃ / s, and the mass fraction of Mn in the cast aluminum alloy is 0.25%-0.35%.
[0058] Further exemplarily, the present application finds that the cooling rate V c is 50 ℃ / s-100 ℃ / s, and the mass fraction M (Mn，%) of Mn in the chemical composition of the cast aluminum alloy satisfies the linear relationship with the cooling rate V cThere is a linear relationship between them. For example, the cooling rate V c may be taken as the abscissa, and the mass fraction M (Mn，%) of Mn in the cast aluminum alloy may be taken as the ordinate, a linear equation is constructed so that the cooling rate V c and the mass fraction M (Mn，%) of Mn in the cast aluminum alloy are in one-to-one correspondence. For example, the linear equation is M (Mn，%) =k2×V c +b2. k2 is 0.001-0.0015. b2 is 0.19-0.20. Further, k2 is 0.00111. b2 is 0.1945. That is, M (Mn，%) =0.00111×V c +0.1945.
[0059] The preparation method of the cast aluminum alloy provided in the present application regulates the mass fraction of Mn in the cast aluminum alloy according to different cooling rates. When the cooling rate is 0.1-20 ℃ / s, a lower Mn content can have a higher solid solubility in the aluminum matrix, which can avoid the enrichment of Mn between dendrites, so the synergy of the cooling rate and the Mn element can avoid the formation of coarse α-Al(Fe, Mn)Si phase. At a higher cooling rate, the ingot solidifies rapidly, which can avoid the local enrichment of Mn elements to form coarse phases; at the same time, a specific Mn content can more fully form stable intermetallic compounds with Fe elements in the cast aluminum alloy, thereby neutralizing the Fe elements and inhibiting the generation of coarse α-Al(Fe, Mn)Si phase.
[0060] The preparation method of the cast aluminum alloy provided in the present application regulates the mass fraction of Mn in the cast aluminum alloy according to different cooling rates, which can inhibit the formation of coarse phases, thereby improving the mechanical properties of the cast aluminum alloy.
[0061] In some examples, the chemical composition of the cast aluminum alloy further includes Cr in a mass fraction of 0.07% to 0.1%. The present application finds that the addition of Cr in the chemical composition of the cast aluminum alloy can form Al7(Cr, Mn) with Mn at a cooling rate of 0.1 ℃ / s to 20 ℃ / s, consume excess Mn, and further inhibit the formation of coarse α-Al(Fe, Mn)Si phases. At a cooling rate of 50 ℃ / s to 100 ℃ / s, 0.07% to 0.1% of Cr can stabilize the dispersed phases, which can preferentially form Al-Cr type dispersed cores (such as Al7Cr phases) with small size and uniform distribution, and the cores have high melting points and are not easy to dissolve at medium and high cooling rates. In addition, the cores can hinder the migration of other solute atoms such as Mn to the existing dispersed phases, avoid the dissolution of small-particle dispersed phases and the abnormal growth of large-particle dispersed phases, and further inhibit the formation of coarse phases. For example, the mass fraction of Cr includes but is not limited to 0.07%, 0.075%, 0.076%, 0.077%, 0.078%, 0.079%, 0.08%, 0.081%, 0.083%, 0.085%, 0.09%, or 0.1%, or a range formed by any two of the above values as end points.
[0062] In some examples, the chemical composition of the cast aluminum alloy further includes the following components in a mass fraction: 80% to 92.43% of Al, 0.05% to 0.2% of Fe, 6% to 8% of Si, 1% to 2.5% of Cu, 0.4% to 0.5% of Mg, 0.06% to 0.12% of Zr, 0.05% to 0.1% of Ti, and 0.01% to 0.3% of Sr.
[0063] In the cast aluminum alloy provided by the present application, Al in a specific mass fraction serves as a matrix and provides a stable dissolution and precipitation environment for other elements. Zr can preferentially combine with Fe to form fine Al-Zr-Fe compound precipitates, and Zr can hinder the diffusion of solute atoms to inhibit the growth of precipitates. Si, Cu, and Mg in specific mass fractions can synergize with each other to form Al-Si-Cu-Mg type fine strengthening phases, and reduce the space for the aggregation of Mn, Fe, and other elements to form large-size precipitates. Ti can refine α-Al grains by forming TiAl3, and the increased grain boundary area can “anchor” precipitates at the grain boundary to avoid the aggregation of the precipitates in the grain. Sr can be adsorbed on the surface of the second phase to hinder the diffusion of solute atoms and indirectly inhibit the size growth of precipitates. Therefore, the above elements can collectively inhibit the formation of large-size precipitates.
[0064] For example, the mass fraction of Al includes but is not limited to 82%, 85%, 88%, 89%, 90%, 91%, 92%, or 92.43%, or a range formed by any two of the above values as end points.
[0065] The mass fraction of Fe includes but is not limited to 0.05%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18% or 0.2%, or a range formed by any two of the above values as end points.
[0066] The mass fraction of Si includes but is not limited to 6%, 6.5%, 6.8%, 7%, 7.1%, 7.18%, 7.2%, 7.5%, 7.8% or 8%, or a range formed by any two of the above values as end points.
[0067] The mass fraction of Cu includes but is not limited to 1%, 1.5%, 1.8%, 1.85%, 1.88%, 1.9%, 2%, 2.2% or 2.5%, or a range formed by any two of the above values as end points.
[0068] The mass fraction of Mg includes but is not limited to 0.4%, 0.43%, 0.44%, 0.447%, 0.45%, 0.48% or 0.5%, or a range formed by any two of the above values as end points.
[0069] The mass fraction of Zr includes but is not limited to 0.06%, 0.07%, 0.075%, 0.078%, 0.08%, 0.085%, 0.088%, 0.09%, 0.1%, 0.11% or 0.12%, or a range formed by any two of the above values as end points.
[0070] The mass fraction of Ti includes but is not limited to 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09% or 0.1%, or a range formed by any two of the above values as end points.
[0071] The mass fraction of Sr includes but is not limited to 0.01%, 0.015%, 0.018%, 0.019%, 0.0191%, 0.023%, 0.025%, 0.028%, 0.03%, 0.1%, 0.2% or 0.3%, or a range formed by any two of the above values as end points.
[0072] Further, the cooling rate V c is 0.1°C / s~20°C / s, and the chemical composition of the cast aluminum alloy includes the following components in mass fraction: 80%~92.43% of Al, 0.05%~0.2% of Fe, 6%~8% of Si, 1%~2.5% of Cu, 0.4%~0.5% of Mg, 0.06%~0.12% of Zr, 0.05%~0.1% of Ti, 0.01%~0.3% of Sr, 0.1%~0.23% of Mn and 0.07%~0.1% of Cr.
[0073] Further, the cooling rate V c is 50℃ / s~100℃ / s, and the chemical composition of the cast aluminum alloy includes, in mass fraction, 80%~92.43% of Al, 0.05%~0.2% of Fe, 6%~8% of Si, 1%~2.5% of Cu, 0.4%~0.5% of Mg, 0.06%~0.12% of Zr, 0.05%~0.1% of Ti, 0.01%~0.3% of Sr, 0.25%~0.35% of Mn, and 0.07%~0.1% of Cr.
[0074] In some examples, the casting is metal mold gravity casting or differential pressure casting.
[0075] The metal mold gravity casting is a casting method in which liquid metal formed after smelting is poured into a casting mold under the action of gravity of the earth, and a casting is obtained after the liquid metal cools and solidifies. For example, the cooling rate of the metal mold gravity casting is 0.1℃ / s~20℃ / s. The differential pressure casting is a special casting method in which liquid metal after smelting is smoothly sucked into a mold cavity and solidified under pressure to form a casting by means of the pressure difference between the gas inside and outside the mold. For example, the cooling rate of the differential pressure casting is 50℃ / s~100℃ / s.
[0076] In some examples, the step of heat treating the ingot includes:
[0077] The ingot is sequentially subjected to solid solution treatment, water quenching treatment, and aging treatment.
[0078] The ingot is sequentially subjected to solid solution treatment, water quenching treatment, and aging treatment, which can dissolve coarse phases through solid solution treatment and make solute atoms uniformly distributed, inhibit the re-aggregation and precipitation of solute atoms through rapid cooling by water quenching, and promote the precipitation of solute as fine strengthening phases through aging, thereby further avoiding the formation of coarse phases and optimizing the microstructure.
[0079] In some examples, the step of solid solution treatment includes:
[0080] a1: the ingot is heated from room temperature to 250℃~350℃ at a heating rate of 150℃ / h~220℃ / h for first-stage heat preservation.
[0081] a2: the temperature is raised to 480℃~510℃ at a heating rate of 150℃ / h~220℃ / h for second-stage heat preservation.
[0082] a3: the temperature is raised to 520℃~550℃ at a heating rate of 150℃ / h~220℃ / h for third-stage heat preservation.
[0083] Further, in step a1, the first segment of the heat preservation treatment has a time period of 4h-8h.
[0084] Further, in step a2, the second segment of the heat preservation treatment has a time period of 2h-6h.
[0085] Further, in step a3, the third segment of the heat preservation treatment has a time period of 2h-6h.
[0086] In the solid solution treatment of the present application, the combination of the segmented temperature rising and the isothermal heat preservation can not only avoid the internal stress or cracking of the ingot due to the excessively large temperature difference by the segmented temperature rising, but also can make the solute atoms fully diffuse and dissolve the coarse initial phase as the temperature gradually rises, and then ensure the uniform distribution of the solute by the isothermal solid solution, thereby improving the solid solution effect.
[0087] For example, the temperature rising rate of step a1, step a2 and step a3 is independently selected from 150℃ / h, 160℃ / h, 170℃ / h, 175℃ / h, 180℃ / h, 185℃ / h, 200℃ / h, 210℃ / h or 220℃ / h, or a range formed by any two of the above values as the end point values.
[0088] The temperature of the first segment of the heat preservation treatment is selected from 250℃, 280℃, 290℃, 295℃, 300℃, 305℃, 310℃, 330℃ or 350℃, or a range formed by any two of the above values as the end point values. The time period of the first segment of the heat preservation treatment is selected from 4h, 5h, 6h, 7h or 8h.
[0089] The temperature of the second segment of the heat preservation treatment is selected from 480℃, 490℃, 495℃, 500℃ or 510℃, or a range formed by any two of the above values as the end point values. The time period of the second segment of the heat preservation treatment is selected from 3h, 4h, 5h or 6h.
[0090] The temperature of the third segment of the heat preservation treatment is selected from 520℃, 525℃, 530℃, 540℃ or 550℃, or a range formed by any two of the above values as the end point values. The time period of the third segment of the heat preservation treatment is selected from 3h, 4h, 5h or 6h.
[0091] In some examples, the temperature of the water quenching treatment is 20℃-60℃. For example, the temperature of the water quenching treatment is selected from 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃ or 60℃, or a range formed by any two of the above values as the end point values.
[0092] In some examples, the aging treatment comprises:
[0093] The intermediate after water quenching treatment is heated at a heating rate of 160 °C / h~200 °C / h to 150 °C~200 °C for heat preservation treatment. Further, the heat preservation treatment time is 8h~12h. The heating rate of this step includes but is not limited to 150 °C / h, 160 °C / h, 170 °C / h, 175 °C / h, 180 °C / h, 185 °C / h, 200 °C / h, 210 °C / h or 220 °C / h, or a range formed by any two of the above point values as end point values. The heat preservation treatment temperature includes but is not limited to 150 °C, 160 °C, 170 °C, 180 °C, 190 °C or 200 °C, or a range formed by any two of the above point values as end point values.
[0094] In one example, the preparation method comprises: (1) determining the Mn chemical composition of the cast aluminum alloy according to the cooling rate of metal type gravity casting; the cast aluminum alloy comprises the following components in mass fraction: 80%~92.43% Al, 0.05%~0.2% Fe, 6%~8% Si, 1%~2.5% Cu, 0.4%~0.5% Mg, 0.06%~0.12% Zr, 0.05%~0.1% Ti, 0.01%~0.3% Sr, 0.1%~0.23% Mn and 0.07%~0.1% Cr.
[0095] (2) preparing raw materials according to the above chemical composition of the cast aluminum alloy, melting, and preparing an ingot after metal type gravity casting; the cooling rate in the casting step is 0.1 °C / s~20 °C / s.
[0096] (3) sequentially performing solid solution treatment, water quenching treatment and aging treatment on the ingot. The solid solution treatment step comprises: heating the ingot from room temperature to 250 °C~350 °C at a heating rate of 150 °C / h~220 °C / h for 4h~8h of first stage heat preservation treatment. Heating to 480 °C~510 °C at a heating rate of 150 °C / h~220 °C / h for 2h~6h of second stage heat preservation treatment. Heating to 520 °C~550 °C at a heating rate of 150 °C / h~220 °C / h for 2h~6h of third stage heat preservation treatment. The intermediate after solid solution treatment is subjected to water quenching treatment at 20 °C~60 °C. The intermediate after water quenching treatment is heated at a heating rate of 160 °C / h~200 °C / h to 150 °C~200 °C for 8h~12h of heat preservation treatment to prepare a cast aluminum alloy.
[0097] In another example, the preparation method comprises: (1) determining the Mn chemical composition of the cast aluminum alloy according to the cooling rate of the differential pressure casting; the cast aluminum alloy comprises the following components in mass fraction: 80% to 92.43% of Al, 0.05% to 0.2% of Fe, 6% to 8% of Si, 1% to 2.5% of Cu, 0.4% to 0.5% of Mg, 0.06% to 0.12% of Zr, 0.05% to 0.1% of Ti, 0.01% to 0.3% of Sr, 0.25% to 0.35% of Mn, and 0.07% to 0.1% of Cr.
[0098] (2) preparing a raw material according to the above chemical composition of the cast aluminum alloy, melting, and preparing an ingot after differential pressure casting; the cooling rate in the casting step is 50 ℃ / s to 100 ℃ / s.
[0099] (3) sequentially performing solid solution treatment, water quenching treatment, and aging treatment on the ingot. The solid solution treatment step comprises: heating the ingot from room temperature to 250 ℃ to 350 ℃ at a heating rate of 150 ℃ / h to 220 ℃ / h for 4 h to 8 h of first-stage heat preservation treatment. Heating to 480 ℃ to 510 ℃ at a heating rate of 150 ℃ / h to 220 ℃ / h for 2 h to 6 h of second-stage heat preservation treatment. Heating to 520 ℃ to 550 ℃ at a heating rate of 150 ℃ / h to 220 ℃ / h for 2 h to 6 h of third-stage heat preservation treatment. Water quenching the intermediate after the solid solution treatment at 20 ℃ to 60 ℃. Heating the intermediate after the water quenching to 150 ℃ to 200 ℃ at a heating rate of 160 ℃ / h to 200 ℃ / h for 8 h to 12 h of heat preservation treatment to prepare the cast aluminum alloy.
[0100] In a second aspect of the present application, a cast aluminum alloy is provided, which is prepared by the preparation method of any one of the first aspect of the present application, and the phase size area of the precipitated phase in the cast aluminum alloy is less than 15 μm.
[0101] The following further specific examples are used to illustrate the present application in detail. It should also be understood that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the scope of protection of the present application. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present application are within the scope of protection of the present application. The specific process parameters in the following examples are only one example in the appropriate range, i.e. those skilled in the art can select within the appropriate range according to the description herein, and do not necessarily have to be limited to the specific values in the following examples.
[0102] Example 1
[0103] (1) The Mn chemical composition of the cast aluminum alloy is determined according to the cooling rate of the metal mold gravity casting; the cast aluminum alloy comprises the following components in mass fraction: 0.1% of Fe, 7.18% of Si, 1.88% of Cu, 0.447% of Mg, 0.087% of Zr, 0.085% of Ti, 0.023% of Sr, 0.194% of Mn, 0.078% of Cr, 0.15% of impurity elements, and the balance of Al.
[0104] (2) The raw material is prepared according to the above chemical composition of the cast aluminum alloy, smelting, and then the ingot is prepared after the metal mold gravity casting; the cooling rate in the casting step is 5 ℃ / s.
[0105] (3) The ingot is sequentially subjected to solid solution treatment, water quenching treatment, and aging treatment. The solid solution treatment step comprises: heating the ingot from room temperature to 300 ℃ at a heating rate of 180 ℃ / h, and then performing first-stage heat preservation treatment at 300 ℃ for 6 h. Heating to 495 ℃ at a heating rate of 180 ℃ / h, and then performing second-stage heat preservation treatment for 4 h. Heating to 525 ℃ at a heating rate of 180 ℃ / h, and then performing third-stage heat preservation treatment for 4 h. The intermediate after the solid solution treatment is subjected to water quenching treatment at 30 ℃. The intermediate after the water quenching treatment is heated to 180 ℃ at a heating rate of 180 ℃ / h for heat preservation treatment for 9 h, to prepare the cast aluminum alloy.
[0106] Example 2
[0107] (1) The Mn chemical composition of the cast aluminum alloy is determined according to the cooling rate of the metal mold gravity casting; the cast aluminum alloy comprises the following components in mass fraction: 0.1% of Fe, 7.18% of Si, 1.88% of Cu, 0.447% of Mg, 0.087% of Zr, 0.085% of Ti, 0.023% of Sr, 0.194% of Mn, 0.078% of Cr, 0.15% of impurity elements, and the balance of Al.
[0108] (2) The raw material is prepared according to the above chemical composition of the cast aluminum alloy, smelting, and then the ingot is prepared after the metal mold gravity casting; the cooling rate in the casting step is 5 ℃ / s.
[0109] (3) The ingot is sequentially subjected to solid solution treatment, water quenching treatment and aging treatment. The solid solution treatment comprises the following steps: the ingot is heated from room temperature to 300°C at a heating rate of 180°C / h, then is subjected to first-stage heat preservation treatment at 300°C for 6h. The temperature is raised to 495°C at a heating rate of 180°C / h, then is subjected to second-stage heat preservation treatment for 4h. The temperature is raised to 525°C at a heating rate of 180°C / h, then is subjected to third-stage heat preservation treatment for 4h. The intermediate after the solid solution treatment is subjected to water quenching treatment at 30°C. The intermediate after the water quenching treatment is heated to 180°C at a heating rate of 180°C / h, and is subjected to heat preservation treatment for 9h to prepare the cast aluminum alloy.
[0110] Comparative Example 1
[0111] (1) The conventional Al-Si-Mg-Cu-Mn cast aluminum alloy comprises the following components in mass fraction: 0.12% of Fe, 7.01% of Si, 1.77% of Cu, 0.472% of Mg, 0.08% of Zr, 0.0675% of Ti, 0.023% of Sr, 0.27% of Mn, 0.15% of impurity elements and the balance of Al.
[0112] (2) The raw material is prepared according to the above chemical composition of the cast aluminum alloy, is melted, and is prepared into an ingot after differential pressure casting. The cooling rate in the casting step is 5°C / s.
[0113] (3) The aluminum alloy is placed in a heat treatment furnace, the ingot is heated from room temperature to 300°C at a rate of 180°C / h, then is heat preserved at 300°C for 6h, then is heated to 495°C at a rate of 180°C / h and is heat preserved for 4h, and then is heated to 525°C at a rate of 180°C / h and is heat preserved for 4h. After completion, water quenching is performed, and the water quenching temperature is 20-60°C. The alloy ingot after the solid solution treatment is placed in a heat treatment furnace, is heated to 180°C at a rate of 180°C / h and is heat preserved for 9h to obtain the final cast aluminum alloy.
[0114] The alloy structure of the cast aluminum alloy prepared in Example 1 is shown in FIG. 1. Figure 1 The alloy structure of the cast aluminum alloy prepared in Example 2 is shown in FIG. 2. Figure 2 The alloy structure of the cast aluminum alloy prepared in Comparative Example 1 is shown in FIG. 3. Figure 3 The statistical diagram of the phase size of the cast aluminum alloys prepared in Example 1 and Comparative Example 1 is shown in FIG. 4. Figure 4 The mechanical property comparison diagram of the cast aluminum alloys prepared in Example 1 and Comparative Example 1 is shown in FIG. 5. Figure 5 The area ratio (area≥15µm) of coarse phases of the cast aluminum alloys prepared in each example and comparative example is shown in Table 1.
[0115] Table 1
[0116]
[0117] As shown in Table 1, Figures 1-5 It can be seen that the application can effectively inhibit the generation of coarse phases and has more excellent mechanical properties through the mutual coordination of the cooling rate and the Mn element.
[0118] The technical features of the above-described embodiments can be combined arbitrarily. In order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present disclosure.
[0119] The above-described embodiments only express several implementation manners of the present application, facilitate the specific and detailed understanding of the technical solutions of the present application, but cannot be understood as the limitation of the patent protection scope of the present application. It should be pointed out that, for the ordinary skilled in the art, on the premise of not departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. It should be understood that, on the basis of the technical solutions provided by the present application, the technical solutions obtained by the skilled in the art through logical analysis, reasoning or limited experiments all belong to the protection scope of the appended claims of the present application. Therefore, the patent protection scope of the present application should be subject to the contents of the appended claims, and the description can be used to explain the contents of the claims.
Claims
1. A method for preparing a cast aluminum alloy, characterized in that, Includes the following steps: According to the chemical composition of the cast aluminum alloy, the raw materials are prepared, smelted, and cast to prepare the ingot; the cooling rate in the casting step is 0.1℃ / s~20℃ / s or 50℃ / s~100℃ / s; The ingot is heat-treated to prepare a cast aluminum alloy. The relationship between the cooling rate during the casting process and the mass fraction of Mn in the chemical composition of the cast aluminum alloy satisfies one of the following characteristics: (1) The cooling rate is 0.1℃ / s to 20℃ / s, and the mass fraction of Mn in the chemical composition of the cast aluminum alloy is 0.1% to 0.23%; (2) The cooling rate is 50℃ / s to 100℃ / s, and the mass fraction of Mn in the chemical composition of the cast aluminum alloy is 0.25% to 0.35%.
2. The method for preparing cast aluminum alloy according to claim 1, characterized in that, The chemical composition of the cast aluminum alloy also includes Cr with a mass fraction of 0.07% to 0.1%.
3. The method for preparing cast aluminum alloy according to claim 2, characterized in that, The chemical composition of the cast aluminum alloy also includes the following components by mass fraction: 80%~92.43% Al, 0.05%~0.2% Fe, 6%~8% Si, 1%~2.5% Cu, 0.4%~0.5% Mg, 0.06%~0.12% Zr, 0.05%~0.1% Ti and 0.01%~0.3% Sr.
4. The method for preparing cast aluminum alloy according to any one of claims 1 to 3, characterized in that, The casting method is either gravity casting or differential pressure casting.
5. The method for preparing cast aluminum alloy according to any one of claims 1 to 3, characterized in that, The steps of heat treating the ingot include: The ingot is subjected to solution treatment, water quenching treatment and aging treatment in sequence.
6. The method for preparing cast aluminum alloy according to claim 5, characterized in that, The solution treatment process includes the following steps: The ingot is heated from room temperature to 250℃~350℃ at a heating rate of 150℃ / h~220℃ / h for the first stage of heat preservation treatment. The temperature is increased to 480℃~510℃ at a heating rate of 150℃ / h~220℃ / h for the second stage of heat preservation treatment; The temperature is increased to 520℃~550℃ at a heating rate of 150℃ / h~220℃ / h for the third stage of heat preservation treatment.
7. The method for preparing cast aluminum alloy according to claim 6, characterized in that, The solution treatment process includes the following steps: The first stage of heat preservation treatment lasts for 4 to 8 hours. And / or, the second stage of heat preservation treatment lasts for 2 to 6 hours; And / or, the third stage of heat preservation treatment takes 2 to 6 hours.
8. The method for preparing cast aluminum alloy according to claim 5, characterized in that, The water quenching temperature is 20℃~60℃.
9. The method for preparing cast aluminum alloy according to claim 5, characterized in that, The steps for timeliness processing include: The intermediate after water quenching was heated to 150℃~200℃ at a heating rate of 160℃ / h~200℃ / h for aging treatment.
10. A cast aluminum alloy, characterized in that, The cast aluminum alloy is prepared by the preparation method according to any one of claims 1 to 9, wherein the size and area of the second phase in the cast aluminum alloy are ≤15μm.