Preparation method for improving thermal fatigue performance of multi-component aluminum alloy and multi-component aluminum-silicon alloy

Abstract

The present invention relates to the technical field of aluminum alloy preparation, and more particularly to a preparation method for improving the thermal fatigue performance of a multinary aluminum-silicon alloy. The present invention provides a preparation method for improving the thermal fatigue performance of a multinary aluminum-silicon alloy. The present invention further refines the structure of the modified alloy through Sr modification, RE modification, ultrasonic treatment, and multi-stage cryogenic treatment. Through the coordinated operation of other preparation processes, the multinary aluminum-silicon alloy obtains better toughness and plasticity, thereby improving the thermal fatigue performance of the alloy. In the present invention, AlSr10 alloy is a modifier, and AlRE alloy is a refining modifier. The combined modification effect brought about by the addition of AlSr10 alloy and AlRE alloy, and the grain refinement effect brought about by ultrasonic treatment and multi-stage cryogenic treatment, improve the thermal fatigue performance of the alloy.

Description

Technical Field

[0001] The present application belongs to the technical field of aluminum alloy preparation, and in particular relates to a preparation method for improving the thermal fatigue performance of multi-component aluminum alloys and a multi-component aluminum-silicon alloy. Background Art

[0002] Further reducing vehicle energy consumption and emissions has become a pressing issue for the automotive industry. Lightweighting is an effective way to achieve energy conservation and emission reduction in vehicles, and the application of new lightweight materials such as aluminum alloys is one of the keys to achieving this goal. Currently, the most widely used automotive aluminum alloy is aluminum-silicon alloy. It offers low density, high specific strength, excellent casting properties, good mechanical properties, wear resistance, and machinability, making it widely used in the manufacture of components such as wheels, bodies, engine blocks, cylinder heads, and pistons.

[0003] Alloying treatment is an important method to improve the microstructure of aluminum alloys and enhance the mechanical properties. As the most important alloying element in aluminum-silicon alloys, the addition of Si can improve the casting properties and mechanical properties of aluminum alloys. It should be noted that the mechanical properties of aluminum-silicon alloys are closely related to the morphology, size and distribution of the eutectic Si phase and the primary Si phase. The primary Si phase in the form of coarse laths or polygonal blocks and the long needle-shaped eutectic Si phase will cause the aluminum alloy matrix to crack and weaken the mechanical properties of the aluminum-silicon alloy. Therefore, aluminum-silicon alloys usually need to be modified to optimize the microscopic characteristics such as the morphology, size and distribution of the Si phase, thereby increasing toughness while improving strength.

[0004] Currently, the main methods for modifying and refining Al-Si alloys include chemical modification, rapid cooling, electromagnetic stirring, ultrasonic treatment, and mechanical vibration. Chemical modification is the most widely used due to its simple operation, low cost, and excellent modification effect. However, single-method modification and refinement methods are no longer sufficient to meet the requirements of Al-Si casting alloys. The combined use of multiple strengthening and toughening methods has become an important research direction in the preparation of Al-Si alloys. Combining these methods with appropriate heat treatment processes can effectively improve the strength and toughness of Al-Si alloys. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method for improving the thermal fatigue performance of a multinary aluminum-silicon alloy and the resulting multinary aluminum-silicon alloy. The preparation method provided by the present invention can significantly improve the thermal fatigue performance of the alloy.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] The present invention provides a preparation method for improving the thermal fatigue performance of a multinary aluminum-silicon alloy, comprising the following steps:

[0008] S1: Melt the multi-component aluminum-silicon alloy or pure metal raw material at 800-820°C, keep the temperature for 30-60 minutes, then skim off the slag and perform ultrasonic treatment to obtain an initial alloy melt;

[0009] S2: Cooling to 700-720°C, adding AlSr10 alloy, stirring evenly after the AlSr10 alloy melts, and keeping the temperature for 20-40 minutes to obtain Sr modified alloy liquid;

[0010] S3: After degassing, refining, and slag removal of the melt obtained in step S2, AlRE alloy is added, and the AlRE alloy is melted, stirred evenly, and kept warm for 10 to 20 minutes before slag removal to obtain RE refined modified alloy liquid;

[0011] S4: ultrasonically treating the melt obtained in step S3, deslagging and filtering the melt, and then casting the melt into a metal mold cavity to obtain a multi-component aluminum-silicon alloy;

[0012] S5: The alloy ingot obtained in step S4 is subjected to solution treatment, multi-stage cryogenic treatment and aging treatment in sequence to obtain a multi-component aluminum-silicon alloy resistant to thermal fatigue.

[0013] The preparation method for improving the thermal fatigue performance of a multi-element aluminum-silicon alloy of the present invention comprises the following chemical compositions, calculated by mass content, of the initial alloy melt in step S1: Si 10-12%, Cu 4.5-5.5%, Mn 0.3-0.6%, Mg 0.6-0.9%, Zn 0.3-0.6%, Cr 0.08-0.15%, Ni 0.05-0.1%, V 0.05-0.1%, and the remainder being Al and unavoidable impurities.

[0014] In the preparation method for improving the thermal fatigue performance of a multi-component aluminum-silicon alloy of the present invention, the resonant frequency of the ultrasonic treatment in step S1 is 20 kHz, the power is 1000 W, and the ultrasonic treatment time is 4 to 6 minutes.

[0015] In the preparation method for improving the thermal fatigue performance of a multi-component aluminum-silicon alloy of the present invention, the amount of Sr added to the AlSr10 alloy in step S2 is 0.02-0.04% of the total mass of the alloy obtained after mixing and melting in step S1.

[0016] The present invention provides a preparation method for improving the thermal fatigue performance of a multi-component aluminum-silicon alloy. In step S3, the chemical composition of the AlRE alloy is 5-6% La, 2-3% Ce, 1-2% Pr, and the remaining rare earth elements are less than 1%, with the balance being Al. The amount of RE added to the Al-RE master alloy is 0.1-0.3% of the total mass of the alloy obtained after mixing and melting in step S1.

[0017] In the preparation method for improving the thermal fatigue performance of a multi-component aluminum-silicon alloy of the present invention, the resonant frequency of the ultrasonic treatment in step S4 is 20 kHz, the power is 1000 W, and the ultrasonic treatment time is 2 to 5 minutes.

[0018] The present invention provides a preparation method for improving the thermal fatigue performance of a multi-component aluminum-silicon alloy. In step S5, the temperature of the solution treatment is 490-510°C, the time is 1-2 hours, and the cooling water temperature is 70-90°C; the multi-stage cryogenic treatment includes sequentially performing shallow cryogenic treatment and cryogenic treatment, the cooling medium of the shallow cryogenic treatment is dry ice, the temperature is -70--90°C, and the time is 2-4 hours; the cooling medium of the cryogenic treatment is liquid nitrogen, the temperature is -140--160°C, and the time is 4-6 hours; and the temperature of the aging treatment is 150-160°C, and the time is 10-16 hours.

[0019] The present invention provides a multinary aluminum-silicon alloy resistant to thermal fatigue, which is prepared by using the preparation method described in any one of the above technical solutions.

[0020] The invention provides a preparation method for improving the thermal fatigue performance of a multinary aluminum-silicon alloy. The method comprises the following steps: melting a multinary aluminum-silicon alloy or a pure metal raw material at 800-820° C., holding the temperature for 30-60 minutes, skimming the slag, and performing ultrasonic treatment to obtain an initial alloy melt; cooling the initial alloy melt to 700-720° C., adding an AlSr10 alloy, stirring the AlSr10 alloy until it melts, and holding the temperature for 20-40 minutes to obtain an Sr modified alloy liquid; degassing, refining, and skimming the Sr modified alloy liquid, adding an AlRE alloy, stirring the AlRE alloy until it melts, and holding the temperature for 10-20 minutes to skim the slag to obtain an RE refined modified alloy liquid; performing ultrasonic treatment on the RE refined modified alloy liquid, skimming the slag, filtering, and casting the RE refined modified alloy liquid into a metal mold cavity to obtain a multinary aluminum-silicon alloy; and sequentially performing a solid solution treatment, a multi-stage cryogenic treatment, and an aging treatment on the multinary aluminum-silicon alloy to obtain a multinary aluminum-silicon alloy resistant to thermal fatigue. The present invention performs composite modification and refinement treatment on the alloy through chemical modification and ultrasonic treatment during the smelting preparation process, and through the coordinated operation of other processes, the multi-component aluminum-silicon alloy obtains better resistance to thermal fatigue. In the present invention, AlSr10 alloy is a modifier, and the Sr element is selectively adsorbed on the twin valleys on the surface of eutectic silicon, causing the eutectic silicon to be modified. The ultrasonic treatment has the effect of refining the grains and precipitating the phase, and the RE element has a modification effect and a refinement effect, and can also purify the melt, thereby improving the thermal fatigue resistance of the multi-component aluminum-silicon alloy.

[0021] Technical effects:

[0022] The multi-component aluminum-silicon alloy prepared by the present invention has a good balance of toughness and strength, achieving excellent thermal fatigue performance. The results of the examples show that the multi-component aluminum-silicon alloy improved by the present invention has high thermal fatigue performance at 26-200°C, 26-300°C, and 26-400°C, which is beneficial for improving the service life of the multi-component aluminum-silicon alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The thermal fatigue performance test results of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 at 26 to 200°C are shown;

[0024] Figure 2 The thermal fatigue performance test results of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 at 26 to 300°C are shown;

[0025] Figure 3 These are the test results of thermal fatigue properties of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 at 26 to 400°C. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] Example 1

[0028] Al-20Si, Al-10Cu, Al-5Mn, Al-5Cr, Al-5Ni, Al-5V, pure Al, pure Mg, and pure Zn were melted at 810°C, kept warm for 50 minutes, and then slag was removed. The original alloy melt was ultrasonically treated for 5 minutes to obtain the original alloy melt. The specific chemical composition was 11.2% Si, 4.9% Cu, 0.5% Mn, 0.4% Zn, 0.8% Mg, 0.07% Ni, 0.11% Cr, 0.06% V, and the balance was Al and unavoidable impurities.

[0029] The original alloy melt was cooled to 710° C., AlSr10 alloy was added, and after the AlSr10 alloy was melted, the mixture was stirred evenly and kept warm for 30 minutes to obtain Sr modified alloy liquid;

[0030] After degassing, refining and deslagging the Sr modified alloy liquid, AlRE alloy is added, and after the AlRE alloy is melted, it is stirred evenly, kept warm for 15 minutes and then deslagging to obtain RE refined modified alloy liquid;

[0031] The RE refined alloy liquid is ultrasonically treated for 3 minutes, the melt is deslagging and filtering, and then cast into a metal mold cavity to obtain a multi-component aluminum-silicon alloy;

[0032] The multi-component aluminum-silicon alloy is subjected to solution treatment, multi-stage cryogenic treatment and aging treatment in sequence to obtain a multi-component aluminum-silicon alloy resistant to thermal fatigue; wherein the solution treatment is specifically heat-keeping at 495°C for 1.5 hours and then placed in 80°C water for cooling; the multi-stage cryogenic treatment is specifically: first heat-keeping in -80°C dry ice for 4 hours; then heat-keeping in -150°C liquid nitrogen for 6 hours; the aging treatment is specifically heat-keeping at 160°C for 10 hours.

[0033] Example 2

[0034] Al-20Si, Al-10Cu, Al-5Mn, Al-5Cr, Al-5Ni, Al-5V, pure Al, pure Mg, and pure Zn were melted at 820°C, kept warm for 30 minutes, and then slag was removed. The original alloy melt was ultrasonically treated for 6 minutes to obtain the original alloy melt. The specific chemical composition was Si: 10%, Cu: 4.5%, Mn: 0.3%, Zn: 0.6%, Mg: 0.9%, Ni: 0.05%, Cr: 0.15%, V: 0.05%, and the balance was Al and unavoidable impurities.

[0035] The original alloy melt was cooled to 710° C., AlSr10 alloy was added, and after the AlSr10 alloy was melted, the mixture was stirred evenly and kept warm for 40 minutes to obtain Sr modified alloy liquid;

[0036] After degassing, refining and deslagging the Sr modified alloy liquid, AlRE alloy is added, and after the AlRE alloy is melted, it is stirred evenly, kept warm for 10 minutes and then deslagging to obtain RE refined modified alloy liquid;

[0037] The RE refined alloy liquid is ultrasonically treated for 2 minutes, the melt is skimmed and filtered, and then cast into a metal mold cavity to obtain a multi-component aluminum-silicon alloy;

[0038] The multi-component aluminum-silicon alloy is subjected to solution treatment, multi-stage cryogenic treatment and aging treatment in sequence to obtain a multi-component aluminum-silicon alloy resistant to thermal fatigue; wherein the solution treatment is specifically heat-keeping at 490°C for 2 hours and then placed in 70°C water for cooling; the multi-stage cryogenic treatment is specifically: first heat-keeping in -80°C dry ice for 3 hours; then heat-keeping in -150°C liquid nitrogen for 5 hours; the aging treatment is specifically heat-keeping at 150°C for 15 hours.

[0039] Example 3

[0040] Al-20Si, Al-10Cu, Al-5Mn, Al-5Cr, Al-5Ni, Al-5V, pure Al, pure Mg, and pure Zn were melted at 800°C, kept warm for 50 minutes, and then slag was removed. The original alloy melt was ultrasonically treated for 5 minutes to obtain the original alloy melt. The specific chemical composition was Si: 12%, Cu: 5.5%, Mn: 0.6%, Zn: 0.3%, Mg: 0.6%, Ni: 0.1%, Cr: 0.08%, V: 0.05%, and the balance was Al and unavoidable impurities.

[0041] The original alloy melt was cooled to 700° C., AlSr10 alloy was added, and after the AlSr10 alloy was melted, the mixture was stirred evenly and kept warm for 30 minutes to obtain Sr modified alloy liquid;

[0042] After degassing, refining and deslagging the Sr modified alloy liquid, AlRE alloy is added, and after the AlRE alloy is melted, it is stirred evenly, kept warm for 15 minutes and then deslagging to obtain RE refined modified alloy liquid;

[0043] The RE refined alloy liquid is ultrasonically treated for 4 minutes, the melt is deslagging and filtering, and then cast into a metal mold cavity to obtain a multi-component aluminum-silicon alloy;

[0044] The multi-component aluminum-silicon alloy is subjected to solution treatment, multi-stage cryogenic treatment and aging treatment in sequence to obtain a multi-component aluminum-silicon alloy resistant to thermal fatigue; wherein the solution treatment is specifically heat-insulating at 500°C for 1 hour and then cooling in 80°C water; the multi-stage cryogenic treatment is specifically: first heat-insulating in -80°C dry ice for 2 hours; then heat-insulating in -150°C liquid nitrogen for 4 hours; the aging treatment is specifically heat-insulating at 155°C for 12 hours.

[0045] Example 4

[0046] Al-20Si, Al-10Cu, Al-5Mn, Al-5Cr, Al-5Ni, Al-5V, pure Al, pure Mg, pure Zn, were melted at 800℃, kept warm for 50 minutes, and then slag was removed. The original alloy melt was ultrasonically treated for 5 minutes to obtain the original alloy melt. The specific chemical composition was Si 10.6%, Cu

[0047] The main components are Mg, Ni, Cr, and V. The main components are Cr, Mn, Zn, Mg, Ni, Cr, and V. The main components are Al, Ni, and unavoidable impurities.

[0048] The original alloy melt was cooled to 705° C., AlSr10 alloy was added, and after the AlSr10 alloy was melted, the mixture was stirred evenly and kept warm for 35 minutes to obtain Sr modified alloy liquid;

[0049] After degassing, refining and deslagging the Sr modified alloy liquid, AlRE alloy is added, and after the AlRE alloy is melted, it is stirred evenly, kept warm for 12 minutes and then deslagging to obtain RE refined modified alloy liquid;

[0050] The RE refined alloy liquid is ultrasonically treated for 3 minutes, the melt is deslagging and filtering, and then cast into a metal mold cavity to obtain a multi-component aluminum-silicon alloy;

[0051] The multi-component aluminum-silicon alloy is subjected to solution treatment, multi-stage cryogenic treatment and aging treatment in sequence to obtain a multi-component aluminum-silicon alloy resistant to thermal fatigue; wherein the solution treatment is specifically heat-insulating at 505°C for 1 hour and then cooling in 80°C water; the multi-stage cryogenic treatment is specifically: first heat-insulating in -80°C dry ice for 3 hours; then heat-insulating in -150°C liquid nitrogen for 5 hours; the aging treatment is specifically heat-insulating at 160°C for 12 hours.

[0052] Comparative Example 1

[0053] The preparation steps are basically the same as those in Comparative Example 1, except that the ultrasonic treatment is omitted.

[0054] Comparative Example 2

[0055] The preparation steps are basically the same as those in Comparative Example 1, except that the addition process of the AlRE alloy and the multi-stage cryogenic treatment process are omitted.

[0056] Effect Examples

[0057] The multi-element aluminum-silicon alloys obtained in Examples 1-4 and Comparative Examples 1-2 were processed into hot and cold fatigue specimens according to national standards. The dimensions of the hot and cold fatigue specimens were 40 mm × 20 mm × 5 mm. A V-shaped notch with a depth of 3 mm was machined into the specimens using a wire cutting method. A circular hole was machined into the other end of the notch to fix the specimens. The hot and cold fatigue specimens were tested on a hot and cold fatigue testing machine at three temperature ranges of 26-200°C, 26-300°C, and 26-400°C. The specimens were removed after every 1000 cycles, polished to remove the surface oxide film, and the crack length at the V-shaped notch was measured. 0.1 mm was used as the crack initiation length, and the number of cycles of crack initiation of the specimens was recorded. The test results are shown as follows: Figures 1 to 3 shown; among them, Figure 1 The thermal fatigue performance test results of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 at 26 to 200°C are shown; Figure 2 The thermal fatigue performance test results of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 at 26 to 300°C are shown; Figure 3 These are the test results of thermal fatigue properties of Examples 1 to 4, Comparative Example 1 and Comparative Example 2 at 26 to 400°C.

[0058] Depend on Figures 1 to 3 It can be seen that after multiple refinement and modification treatments and multi-stage cryogenic treatments, the multi-component aluminum-silicon alloy has a good combination of toughness and strength, and has achieved better cold and hot fatigue performance.

[0059] The above description is merely a preferred embodiment of the present invention. Based on the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A preparation method for improving the thermal fatigue performance of multi-element aluminum-silicon alloy, characterized in that: The following steps are involved: S1: Melt the multi-component aluminum-silicon alloy or pure metal raw material at 800-820°C, keep the temperature for 30-60 minutes, then skim off the slag and perform ultrasonic treatment to obtain an initial alloy melt; S2: Cooling to 700-720°C, adding AlSr10 alloy, stirring evenly after the AlSr10 alloy melts, and keeping the temperature for 20-40 minutes to obtain Sr modified alloy liquid; S3: After degassing, refining, and slagging the melt obtained in step S2, AlRE alloy is added, and the AlRE alloy is melted, stirred evenly, and kept warm for 10 to 20 minutes before slagging to obtain RE refined modified alloy liquid; S4: ultrasonically treating the melt obtained in step S3, deslagging and filtering the melt, and then casting the melt into a metal mold cavity to obtain a multi-component aluminum-silicon alloy; S5: performing solution treatment, multi-stage cryogenic treatment, and aging treatment on the alloy ingot obtained in step S4 to obtain a multi-component aluminum-silicon alloy resistant to thermal fatigue; The chemical composition of the initial alloy melt in step S1 is, by mass content, 10-12% Si, 4.5-5.5% Cu, 0.3-0.6% Mn, 0.6-0.9% Mg, 0.3-0.6% Zn, 0.08-0.15% Cr, 0.05-0.1% Ni, 0.05-0.1% V, and the balance being Al and unavoidable impurities. The chemical composition of the AlRE alloy in step S3 is La 5-6%, Ce 2-3%, Pr 1-2%, the remaining rare earth elements are less than 1%, and the balance is Al; the amount of RE added to the Al-RE master alloy is 0.1-0.3% of the total mass of the alloy obtained after mixing and melting in step S1; The multi-stage cryogenic treatment includes shallow cryogenic treatment and deep cryogenic treatment in sequence, wherein the cooling medium of the shallow cryogenic treatment is dry ice, the temperature is -70 to -90°C, and the time is 2 to 4 hours; the cooling medium of the deep cryogenic treatment is liquid nitrogen, the temperature is -140 to -160°C, and the time is 4 to 6 hours; the temperature of the aging treatment is 150 to 160°C, and the time is 10 to 16 hours.

2. A preparation method for improving the thermal fatigue performance of multi-component aluminum-silicon alloy according to claim 1, characterized in that: The resonant frequency of the ultrasonic treatment in step S1 is 20 kHz, the power is 1000 W, and the ultrasonic treatment time is 4 to 6 minutes.

3. The method for improving the thermal fatigue performance of a multinary aluminum-silicon alloy according to claim 1, wherein: The amount of Sr added to the AlSr10 alloy in step S2 is 0.02-0.04% of the total mass of the alloy obtained after mixing and melting in step S1.

4. A preparation method for improving the thermal fatigue performance of multinary aluminum-silicon alloy according to claim 1, characterized in that: The resonant frequency of the ultrasonic treatment in step S4 is 20 kHz, the power is 1000 W, and the ultrasonic treatment time is 2 to 5 minutes.

5. The method for improving the thermal fatigue performance of a multinary aluminum-silicon alloy according to claim 1, wherein: The temperature of the solution treatment in step S5 is 490-510°C, the time is 1-2 hours, and the cooling water temperature is 70-90°C.

6. A multi-component aluminum-silicon alloy, characterized in that: The preparation method is described in any one of claims 1 to 5.

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