Medium-strength aluminum alloy with excellent impact resistance and preparation method thereof

Abstract

The invention provides an aluminum alloy with moderate strength and excellent impact resistance and a preparation method thereof, and belongs to the technical field of aluminum alloys. The high-strength and high-toughness alloy material comprises the following components in percentage by mass: 4.4%-5.1% of Zn, 1.2%-1.5% of Mg, 0.3%-0.6% of Mn, 0.08%-0.18% of Zr, 0.08%-0.15% of Er and the balance of Cr. 0.05%, Tilt; the aluminum alloy comprises, by mass, 0.05% of Cu, Si, Fe, the balance Al and inevitable impurities, the total mass percent of all the inevitable impurities is smaller than 0.15%, and the mass percent of a single inevitable impurity is smaller than 0.05%. By optimizing the component design of the aluminum alloy, the aluminum alloy with medium-high strength, good plasticity and excellent impact resistance is obtained.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, and in particular to an aluminum alloy with excellent medium-strength impact resistance and its preparation method. Background Technology

[0002] 7000 series aluminum alloys, as a type of high-strength wrought aluminum alloy, have been widely used in aerospace, rail transportation, and weaponry due to their excellent specific strength and good machinability. However, in some critical structural components requiring high material toughness and impact resistance, traditional 7000 series aluminum alloys often suffer from insufficient impact toughness, which limits their application range to some extent. Currently, industry research on 7000 series aluminum alloys focuses primarily on improving strength and fatigue performance, while systematic research on their impact performance, especially the dynamic impact response under complex service environments, is relatively scarce. Specifically, the influence mechanism of the content ratio of major alloying elements such as zinc, magnesium, and copper and their interactions on impact performance remains unclear; the intrinsic mechanism by which heat treatment processes such as solution temperature, holding time, quenching rate, and aging regime affect the type, size, distribution of precipitates, and their interaction with dislocations, thus influencing impact performance, also needs further clarification. Summary of the Invention

[0003] In view of this, in order to obtain an aluminum alloy with excellent medium-strength impact resistance, the present invention provides an aluminum alloy with excellent medium-strength impact resistance and its preparation method. By optimizing the composition design of the aluminum alloy, an aluminum alloy with medium-high strength, good plasticity and excellent impact resistance is obtained.

[0004] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides an aluminum alloy with excellent medium-strength impact resistance, comprising the following components by mass percentage: Zn: 4.4–5.1%, Mg: 1.2–1.5%, Mn: 0.3–0.6%, Zr: 0.08–0.18%, Er: 0.08–0.15%, Cr <0.05%, Ti <0.05%, and also contains Cu and Si elements. , Fe element content The balance is Al and unavoidable impurities, with the total mass percentage of all unavoidable impurities being <0.15% and the mass percentage of a single unavoidable impurity being <0.05%.

[0005] Secondly, the present invention provides a method for preparing the above-mentioned aluminum alloy with excellent medium-strength impact resistance, comprising the following steps: Step (1): Weigh the raw materials according to the mass percentage of each element, and then melt, refine, remove slag, degas online, and filter the weighed raw materials before casting to obtain as-cast ingots; Step (2): The as-cast ingot obtained in step (1) is heated and forged to obtain a forging; Step (3): After the forgings obtained in step (2) are subjected to solution quenching and artificial aging treatment in sequence, they are taken out of the furnace and air cooled to obtain aluminum alloy.

[0006] Compared with the prior art, the present invention has the following beneficial effects: Balance between medium and high strength and good plasticity: room temperature tensile strength ≥450MPa (478MPa in the example), elongation ≥13% (13.5% in the example), with both load-bearing capacity and processing deformation capacity.

[0007] Excellent impact resistance: Impact absorption energy KU2≥13J (16.5J at room temperature in the example, and still 15.8J at -40℃), with outstanding low-temperature impact resistance.

[0008] Fine grain structure improves overall performance: The grain size reaches level 4 or above (level 5.5 in the example), and the fine grain structure effectively enhances the toughness and fatigue life of the material.

[0009] Strict impurity control: individual impurity element <0.05%, total impurities <0.15%, reducing the negative impact of internal defects on performance.

[0010] Stable and reliable process: Through standardized smelting (730-760℃), forging (final forging ≥380℃), and heat treatment (solution treatment 460-480℃ + aging 150-170℃) processes, the consistency of product performance is ensured. Detailed Implementation

[0011] This invention provides an aluminum alloy with excellent medium-strength impact resistance, characterized in that it comprises the following components by mass percentage: Zn: 4.4–5.1%, Mg: 1.2–1.5%, Mn: 0.3–0.6%, Zr: 0.08–0.18%, Er: 0.08–0.15%, Cr <0.05%, Ti <0.05%, and also contains Cu and Si elements. , Fe element content The balance is Al and unavoidable impurities, with the total mass percentage of all unavoidable impurities being <0.15% and the mass percentage of a single unavoidable impurity being <0.05%.

[0012] In this invention, the aluminum alloy preferably comprises the following components by weight percentage: Zn: 4.65%, Mg: 1.32%, Mn: 0.45%, Zr: 0.12%, Er: 0.11%, Cu: 0.72%, Si: 0.43%, Fe: 0.10%, Cr: 0.03%, Ti: 0.03%, with the balance being Al and unavoidable impurities.

[0013] This invention provides a method for preparing the above-mentioned aluminum alloy with excellent medium-strength impact resistance, comprising the following steps: Step (1): Weigh the raw materials according to the mass percentage of each element, and then melt, refine, remove slag, degas online, and filter the weighed raw materials before casting to obtain as-cast ingots; In step (1), the melting temperature is 730-760℃; the refining agent is added by argon gas at a rate of 1kg / min; the slag after refining is removed by mechanical slag rake; the degassing is done by argon gas at a rate of 30-35L / min; the filtration is done by 40+50PPI filter plates; the preferred casting specification is a round ingot with a diameter of φ178-360mm.

[0014] Step (2): The as-cast ingot obtained in step (1) is heated and forged to obtain a forging; In step (2), the temperature is maintained at 350-400℃ for 3-6 hours, and then the temperature is raised to 455-470℃ and maintained for 4-6 hours for forging.

[0015] Forging process: forging speed ≤25mm / s, final forging temperature ≥380℃.

[0016] Step (3): After the forgings obtained in step (2) are subjected to solution quenching and artificial aging treatment in sequence, they are taken out of the furnace and air cooled to obtain aluminum alloy.

[0017] In step (3), the solution quenching temperature is 460-480℃, the holding time is 3-5h, the quenching medium is water at 30-60℃, and then artificial aging is carried out. The aging process is: heating to 150-170℃ and holding for 8-14h, then air cooling after removal from the furnace.

[0018] The technical solution of the present invention will be clearly and thoroughly described below with reference to specific embodiments.

[0019] Example 1 Alloy composition design: Zn: 4.65%, Mg: 1.32%, Mn: 0.45%, Zr: 0.12%, Er: 0.11%, Cu: 0.72%, Si: 0.43%, Fe: 0.10%, Cr: 0.03%, Ti: 0.03%, with the balance being Al and unavoidable impurities. Other impurity elements must individually be <0.05%, and the total amount of other impurity elements must be <0.15%. Step (1): Use molten aluminum (99.85% purity), magnesium ingots (99.90% purity), zinc ingots (99.995% purity), 10% aluminum-zirconium master alloy, 5% aluminum-erbium alloy, cathode copper plate, manganese additive, and chromium additive to make the ingredients.

[0020] Step (2): Melting temperature 745℃; refining agent is added by argon gas at a rate of 1kg / min; after refining, the slag is removed by mechanical slag rake; degassing is performed by argon gas at a rate of 30L / min; filtration is performed by 40+50PPI filter plate; casting specification is φ178mm round ingot.

[0021] Step (3): After sawing the ingot, heat it at 350℃ for 6 hours, then raise the temperature to 460℃ and hold for 6 hours. The heated billet is then forged at a forging speed of 25 mm / s and a final forging temperature of 400℃.

[0022] Step (4): Perform solution quenching on the forging at a temperature of 465℃ for 3.5 hours and a quenching water temperature of 45℃. Perform aging treatment on the forging at a temperature of 160℃ for 10 hours, and then air cool it to obtain the aluminum alloy.

[0023] Step (5): The aluminum alloy was subjected to room temperature tensile testing. The tensile strength was 478 MPa, the elongation was 13.5%, the KU2 result at room temperature was 16.5 J, and at -40℃, the KU2 result was 15.8 J. According to the intercept method of GB / T 3246.1, the grain size grade reached 5.5.

[0024] Example 2 Same as Example 1, except for the alloy composition design: Zn: 5.1%, Mg: 1.5%, Mn: 0.3%, Zr: 0.18%, Er: 0.08%, Cu: 0.80%, Si: 0.5%, Fe: 0.12%, Cr: 0.04%, Ti: 0.03%, with the balance being Al and unavoidable impurities. Other impurity elements must individually be <0.05%, and the total amount of other impurity elements must be <0.15%.

[0025] The aluminum alloy was subjected to room temperature tensile testing. The tensile strength was 455 MPa, the elongation was 13.0%, and the KU2 result was 16.0 J at room temperature and 15.5 J at -40℃. The grain size grade reached 5.0 according to the intercept method of GB / T 3246.1.

[0026] Example 3 Same as Example 1, except for the alloy composition design: Zn: 4.4%, Mg: 1.2%, Mn: 0.6%, Zr: 0.08%, Er: 0.15%, Cu: 0.70%, Si: 0.4%, Fe: 0.15%, Cr: 0.02%, Ti: 0.04%, with the balance being Al and unavoidable impurities. Other impurity elements must individually be <0.05%, and the total amount of other impurity elements must be <0.15%.

[0027] The aluminum alloy was subjected to room temperature tensile testing. The tensile strength was 468 MPa, the elongation was 13.5%, the KU2 result was 15.5 J at room temperature, and 15.3 J at -40℃. The grain size grade reached 5.0 according to the intercept method of GB / T 3246.1.

[0028] Example 4 Same as Example 1, except that the melting temperature is 760℃, the argon gas rate is 35L / min, the heating and forging process is held at 400℃ for 3 hours, then the temperature is raised to 455℃ and held for 4 hours, the solution quenching temperature is 480℃ and the holding time is 5 hours, the quenching medium is water at 30℃, and the aging process is: heated to 150℃ and held for 8 hours.

[0029] The aluminum alloy was subjected to room temperature tensile testing. The tensile strength was 470 MPa, the elongation was 13.5%, the KU2 result was 14.6 J at room temperature, and 15.0 J at -40℃. The grain size grade reached 5.5 according to the intercept method of GB / T 3246.1.

[0030] Example 5 Same as Example 1, except that the melting temperature is 730℃, the argon gas rate is 33L / min, the heating and forging process is held at 380℃ for 4 hours, then the temperature is raised to 470℃ and held for 3 hours, the solution quenching temperature is 470℃ and the holding time is 3 hours, the quenching medium is water at 60℃, and the aging process is: heated to 170℃ and held for 14 hours.

[0031] The aluminum alloy was subjected to room temperature tensile testing. The tensile strength was 465 MPa, the elongation was 14.0%, and the KU2 result was 15.8 J at room temperature and 16.2 J at -40℃. The grain size grade reached 5.0 according to the intercept method of GB / T 3246.1.

[0032] Comparative Example 1 Same as Example 1, except for the alloy composition: Zn: 4.66%, Mg: 1.44%, Mn: 0.55%, Zr: 0.11%, Er: 0.13%, Cu: 0.69%, Si: 0.39%, Fe: 0.16%, Cr: 0.02%, Ti: 0.04%, with the balance being Al and unavoidable impurities. Other impurity elements must individually be <0.05%, and the total amount of other impurity elements must be <0.15%.

[0033] The aluminum alloy was subjected to room temperature tensile testing. The tensile strength was 400 MPa, the elongation was 11.9%, and the KU2 result was 11.0 J at room temperature. At -40℃, the KU2 result was 10.6 J. According to the intercept method of GB / T 3246.1, the grain size grade reached 3.0.

[0034] Comparative Example 2 Same as Example 1, except that the melting temperature is 720℃, the argon gas rate is 25L / min, the heating and forging process is carried out at 330℃ for 5 hours, then the temperature is raised to 440℃ and held for 4 hours, the solution quenching temperature is 450℃ and the holding time is 4.5 hours, the quenching medium is water at 45℃, and the aging process is: heating to 140℃ and holding for 9 hours.

[0035] The aluminum alloy was subjected to room temperature tensile testing. The tensile strength was 410 MPa, the elongation was 12.0%, and the KU2 result was 12.0 J at room temperature and 12.5 J at -40℃. The grain size grade reached 3.5 according to the intercept method of GB / T 3246.1.

[0036] As can be seen from Examples 1-3 and Comparative Example 1, Zn / Cu≈6.75, exceeding the limit of 6.5, and Mg / Si≈3.69, exceeding the limit of 3.5, resulting in a significant reduction in tensile strength and impact performance.

[0037] As can be seen from Examples 4-5 and Comparative Example 2, the process parameters in Comparative Example 2 are outside the parameter range defined by the present invention, which also leads to a significant reduction in its tensile strength and impact performance.

[0038] The above description is merely a preferred embodiment of the present invention. However, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention should be covered within the scope of protection of the present invention.

Claims

1. An aluminum alloy with excellent medium-strength impact resistance, characterized in that, It comprises the following components by mass percentage: Zn: 4.4–5.1%, Mg: 1.2–1.5%, Mn: 0.3–0.6%, Zr: 0.08–0.18%, Er: 0.08–0.15%, Cr <0.05%, Ti <0.05%, and also contains Cu and Si elements. , Fe element content The balance is Al and unavoidable impurities, with the total mass percentage of all unavoidable impurities being <0.15% and the mass percentage of a single unavoidable impurity being <0.05%.

2. The aluminum alloy with excellent medium-strength impact resistance according to claim 1, characterized in that, According to mass percentage, it includes the following components: Zn: 4.65%, Mg: 1.32%, Mn: 0.45%, Zr: 0.12%, Er: 0.11%, Cu: 0.72%, Si: 0.43%, Fe: 0.10%, Cr: 0.03%, Ti: 0.03%, with the balance being Al and unavoidable impurities.

3. The method for preparing a medium-strength aluminum alloy with excellent impact resistance according to claim 1 or 2, characterized in that, Includes the following steps: Step (1): Weigh the raw materials according to the mass percentage of each element, and then melt, refine, remove slag, degas online, and filter the weighed raw materials before casting to obtain as-cast ingots; Step (2): The as-cast ingot obtained in step (1) is heated and forged to obtain a forging; Step (3): After the forgings obtained in step (2) are subjected to solution quenching and artificial aging treatment in sequence, they are taken out of the furnace and air cooled to obtain aluminum alloy.

4. The method for preparing a medium-strength aluminum alloy with excellent impact resistance according to claim 3, characterized in that, In step (1), the melting temperature is 730-760℃.

5. The method for preparing a medium-strength aluminum alloy with excellent impact resistance according to claim 3, characterized in that, In step (1), the refining agent is added by argon gas at a rate of 1 kg / min.

6. The method for preparing a medium-strength aluminum alloy with excellent impact resistance according to claim 3, characterized in that, In step (1), argon gas is used for online degassing at a rate of 30-35 L / min.

7. The method for preparing a medium-strength aluminum alloy with excellent impact resistance according to claim 3, characterized in that, In step (2), the temperature is kept at 350-400℃ for 3-6 hours, and then the temperature is raised to 455-470℃ and kept for 4-6 hours for forging.

8. The method for preparing a medium-strength aluminum alloy with excellent impact resistance according to claim 3, characterized in that, In step (2), the forging speed is ≤25mm / s and the final forging temperature is ≥380℃.

9. The method for preparing a medium-strength aluminum alloy with excellent impact resistance according to claim 3, characterized in that, In step (3), the solution quenching temperature is 460-480℃, the holding time is 3-5h, and the quenching medium is water at 30-60℃.

10. A method for preparing a medium-strength aluminum alloy with excellent impact resistance according to any one of claims 3-9, characterized in that, In step (3), the artificial aging time is: heating to 150-170℃ and keeping warm for 8-14 hours.

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