Aluminum alloy and preparation method and application thereof

Abstract

The invention discloses an aluminum alloy as well as a preparation method and application thereof, the aluminum alloy comprises the following components in percentage by weight: 0.1 to 0.2 percent of Cu, 0.4 to 0.5 percent of Mn, 0.2 to 0.5 percent of Zn and 0.15 to 0.2 percent of Cr, and the weight ratio of Mn to Cr is 2.5 to 3. According to the aluminum alloy, precipitation of precipitation strengthening phases such as beta and Q is promoted to the maximum extent, the Mn / Cr content ratio is controlled, and a fine and evenly-distributed alpha-Al (FeMnCr) Si dispersed phase is obtained in combination with two-stage homogenization treatment, so that the purpose of grain refinement is achieved, and the mechanical property and corrosion resistance of a 6-series aluminum alloy profile are greatly improved on the basis of precipitation strengthening and fine grain strengthening.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to an aluminum alloy and a preparation method and application thereof. Background Art

[0002] 6 series aluminum alloys (Al-Mg-Si series) have become key structural materials for transportation vehicles due to their advantages such as light weight, corrosion resistance and good machinability. For example, aluminum alloys such as 6061, 6082 and 6110A with strength levels of 300-350MPa are used for key components such as body panels, compartments, bodies, crossbeams and pillow blocks. However, in the context of the equipment manufacturing industry's increasing pursuit of energy conservation, emission reduction and high performance, the existing 300-350MPa 6 series aluminum alloy strength still cannot meet the urgent requirements for further weight reduction of vehicles and the needs of lightweight development of new transportation vehicles. Therefore, in view of the above-mentioned low strength characteristics, some researchers have further increased the strength to more than 400MPa by increasing the content of the main alloying elements Mg and Si and trace alloying elements Cu, Cr, Mn, Zr, etc., but higher alloying elements will further deteriorate the corrosion performance and extrudability of profiles.

[0003] Therefore, it is necessary to provide a high-strength and corrosion-resistant Al-Mg-Si alloy that meets the lightweight requirements. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides an aluminum alloy, which has high strength through compounding of raw materials, and the profile strength can reach more than 400MPa, and has good corrosion resistance and extrudability.

[0005] The invention also provides a method for preparing the aluminum alloy.

[0006] The present invention also proposes an application of the aluminum alloy in transportation vehicles.

[0007] According to one aspect of the present invention, an aluminum alloy is provided, comprising the following components, by weight percentage: Cu 0.1-0.2wt.%, Mn 0.4-0.5wt.%, Zn 0.2-0.5wt.%, Cr 0.15-0.2wt.%, wherein the weight ratio of Mn to Cr is 2.5-3.

[0008] According to the first aspect of the present invention, there are at least the following beneficial effects:

[0009] Usually, in order to achieve high-strength aluminum alloy, the Cu content is controlled at 0.5-0.8.wt%. During the aging process, Q phase (AlMgSiCu phase) and Cu-rich phase at the grain boundary can be formed, thereby improving the mechanical properties of the alloy. Although these phases can produce a large strengthening effect, they will seriously affect the intergranular corrosion performance of the alloy. Therefore, in the present invention, the Cu element content is controlled at 0.1-0.2.wt%. On the basis of not seriously affecting the corrosion performance of the alloy, an appropriate amount of Cu-rich phase can be obtained to improve the mechanical properties of the alloy.

[0010] In the present invention, the Zn content is controlled at 0.2-0.5 wt%. On the one hand, since the vacancy binding capacity of Zn atoms is between that of Si and Mg, the Mg-Si phase containing Zn will be preferentially formed during the aging process, and the Mg-Zn phase cannot be formed, so the influence on the corrosion ability of the alloy is small. On the other hand, the addition of Zn will promote the formation of Mg-Si atomic clusters, effectively improve the aging precipitation rate of the alloy, make the size of the β" phase small and dispersed, and slightly increase the number density, thereby improving the precipitation strengthening effect of the alloy.

[0011] In the present invention, the Mn content is controlled at 0.4-0.5wt.%, the Cr content is controlled at 0.1-0.2wt.%, and the Mn / Cr content ratio is set within the range of 2.5-3. The existing technology does not limit the Mn / Cr content ratio. However, the 6-series aluminum alloy needs to be homogenized to obtain a fine and dispersed α-AlFeMnSi dispersed phase, so as to obtain more sub-grain structures during the extrusion deformation process and improve the mechanical properties and corrosion properties of the alloy. When the Mn / Cr content ratio is too high, the α-Al (FeMnCr) Si dispersed phase particle size is large and it is difficult to achieve a grain refinement effect. When the Mn / Cr content ratio is too low, the number of α-Al (FeMnCr) Si dispersed phase particles is small, and the grain refinement effect is also weakened.

[0012] In some embodiments of the present invention, the aluminum alloy further comprises: Mg 0.9-1.2 wt.%.

[0013] In some embodiments of the present invention, the composition of the aluminum alloy further includes: Si 1.0-1.4wt.%.

[0014] An aluminum alloy comprises the following components by weight percentage: Cu 0.1-0.2wt.%, Mn 0.4-0.5wt.%, Zn 0.2-0.5wt.%, Cr 0.15-0.2wt.%, Mg 0.9-1.2wt.%, Si 1.0-1.4wt.%, and the balance is aluminum, wherein the weight ratio of Mn to Cr is 2.5-3.

[0015] According to two aspects of the present invention, a method for preparing an aluminum alloy is provided, comprising the following steps:

[0016] S1: melting and casting an aluminum ingot and a raw material containing the aluminum alloy component to obtain an aluminum alloy ingot;

[0017] S2: homogenizing the aluminum alloy ingot obtained in step S1;

[0018] S3: extruding the aluminum alloy ingot obtained in step S2 to obtain an aluminum alloy extruded profile;

[0019] S4: The extruded profile is subjected to solution quenching and then aging treatment.

[0020] According to the second aspect of the present invention, there are at least the following beneficial effects:

[0021] In some embodiments of the present invention, the melting temperature is 730-750°C; and / or the casting temperature is 730-740°C.

[0022] In some embodiments of the present invention, the homogenization step includes: heating the aluminum alloy ingot to 460-480°C and keeping it for 6-8h, then heating it to 530-550°C at a rate of 5-8°C / min, keeping it for 8-12h, then cooling it to 380-400°C at a cooling rate not higher than 15°C / min, and then cooling it to room temperature at a cooling rate not lower than 35°C / min.

[0023] The smelting casting, hot extrusion, solution quenching and aging treatment in the present invention are similar to the traditional 6 series aluminum alloy processing method. The difference is that the homogenization treatment adopts a two-stage homogenization treatment. The first stage is 460-480°C for 6-8 hours, and the main purpose is to allow the nano-scale α-Al(FeMnCr)Si dispersed phase to nucleate. The second stage is 530-550°C for 8-12 hours, and the main purpose is to eliminate dendrite segregation and transform the coarse flaky micron-scale β-AlFeSi phase into a fine spherical α-AlFeSi phase.

[0024] In addition, during the homogenization cooling process of the 6 series aluminum alloy in the present invention, if the cooling rate is too low, a Mg2Si quenching precipitation phase will be generated, and it will be difficult to eliminate the Mg2Si phase in the subsequent hot extrusion process, resulting in reduced extrudability and even cracking of the profile. If the cooling rate is too fast, the ingot will also crack, affecting the extrusion performance. Therefore, the homogenization cooling rate is optimized, and a cooling rate of no more than 15°C / min is used in the high temperature section (>400°C) to avoid cracking of the ingot. In the low temperature section (<400°C), a cooling rate of no less than 35°C / min is used to avoid the precipitation temperature of the Mg2Si phase.

[0025] In summary, compared with the prior art, the beneficial technical effects of the present invention are as follows: by reasonably adding low-cost alloying elements such as Cu and Zn, the precipitation of precipitation-strengthening phases such as β and Q is promoted to the maximum extent, the Mn / Cr content ratio is controlled, and a fine and uniformly distributed α-Al(FeMnCr)Si dispersed phase is obtained in combination with a two-stage homogenization treatment, thereby achieving the purpose of grain refinement, and greatly improving the mechanical properties and corrosion properties of the 6 series aluminum alloy profiles on the basis of precipitation strengthening and fine grain strengthening.

[0026] In some embodiments of the present invention, the extrusion temperature is 450-470° C., and the extrusion time is 1-2 h.

[0027] In some embodiments of the present invention, the temperature of the solid solution quenching is 530-550° C., and the time of the solid solution quenching is 40-80 min.

[0028] In some embodiments of the present invention, in step S3, in the step of solution quenching, the temperatures of the extrusion barrel, the extrusion pad and the extrusion die are all 460-480°C; the extrusion ratio is 25-30; and the extrusion speed does not exceed 8m / min.

[0029] In some embodiments of the present invention, the temperature of the aging treatment is 165-175° C., and the time of the aging treatment is 6-10 h.

[0030] According to three aspects of the present invention, an application of an aluminum alloy in transportation vehicles is proposed. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0032] Figure 1 TEM image of the homogenized state of Example 1;

[0033] Figure 2 EBSD image of the extruded state of Example 1;

[0034] Figure 3 This is the TEM image of the homogenized state of Comparative Example 1. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0036] Example 1

[0037] This embodiment provides a 6 series aluminum alloy, with specific contents as follows: Mg content: 1.2wt.%, Si content: 1.4wt.%, Cu content: 0.1wt.%, Mn content: 0.4wt.%, Zn content: 0.2wt.%, Fe content: ≤0.1wt.%, Cr content: 0.15wt.%, and the remainder is Al. The sum of the weight percentages of the components is 100%, of which Mn / Cr: 2.7.

[0038] This embodiment also provides a method for preparing a 6 series aluminum alloy, specifically:

[0039] S1. The ingot is prepared by a semi-continuous ingot casting method, with a melting temperature of 750°C and a casting temperature of 740°C;

[0040] S2. The primary homogenization temperature is 480℃, which is kept for 6 hours, then heated to 530℃ at a rate of 5℃ / min and kept for 12 hours. The ingot is first cooled to 380℃ at a cooling rate of 10℃ / min, and then cooled to room temperature at a cooling rate of 45℃ / min.

[0041] S3. The homogenized ingot was heated to 470°C and kept warm for 1h; the temperature of the extrusion cylinder, the extrusion pad and the extrusion die were all 480°C; the extrusion ratio was 30; the extrusion speed was 5m / min to obtain an extruded profile;

[0042] S4. The obtained extruded profile is kept at 530°C for 80 minutes, then water-cooled to room temperature and then aged at 165°C for 10 hours.

[0043] Example 1 TEM photo of the homogenized state is as follows Figure 1 As shown in Figure 2, there is a fine dispersed α-Al(FeMnCr)Si phase in the matrix. The area fraction of the dispersed phase is 2.4% and the size is 18.6nm. The EBSD photo of the extruded state is shown in Figure 2. Figure 2 As shown, it can be found that the grain structure is fine and distributed in a band-like manner along the extrusion direction.

[0044] Example 2

[0045] This embodiment provides a 6 series aluminum alloy, with specific contents as follows: Mg content: 0.9wt.%, Si content: 1.0wt.%, Cu content: 0.2wt.%, Mn content: 0.5wt.%, Zn content: 0.5wt.%, Fe content: ≤0.1wt.%, Cr content: 0.2wt.%, and the remainder is Al. The sum of the weight percentages of the components is 100%, where Mn / Cr: 2.5.

[0046] This embodiment also provides a method for preparing a 6 series aluminum alloy, specifically:

[0047] S1. The ingot is prepared by a semi-continuous ingot casting method, with a melting temperature of 740°C and a casting temperature of 730°C;

[0048] S2. The primary homogenization temperature is 460°C, kept at this temperature for 8 hours, then heated to 550°C at a rate of 5°C / min, kept at this temperature for 8 hours, the ingot is first cooled to 400°C at a cooling rate of 15°C / min, and then the ingot is cooled to room temperature at a cooling rate of 40°C / min;

[0049] S3. The homogenized ingot was heated to 450°C and kept warm for 2h; the temperature of the extrusion cylinder, extrusion pad and extrusion die was 460°C; the extrusion ratio was 25; the extrusion speed was 4m / min;

[0050] S4. The obtained extruded profile is kept at 550°C for 40 minutes, then water-cooled to room temperature and then aged at 175°C for 8 hours.

[0051] Example 3

[0052] This embodiment provides a 6 series aluminum alloy, with specific contents as follows: Mg content: 1.0wt.%, Si content: 1.2wt.%, Cu content: 0.2wt.%, Mn content: 0.5wt.%, Zn content: 0.4wt.%, Fe content: ≤0.1wt.%, Cr content: 0.17wt.%, and the remainder is Al. The sum of the component weight percentages is 100%, of which Mn / Cr: 2.9.

[0053] This embodiment also provides a method for preparing a 6 series aluminum alloy, specifically:

[0054] S1. The ingot is prepared by a semi-continuous ingot casting method, with a melting temperature of 750°C and a casting temperature of 730°C;

[0055] S2. The primary homogenization temperature is 470°C, kept at this temperature for 8 hours, then heated to 550°C at a rate of 5°C / min, kept at this temperature for 10 hours, the ingot is first cooled to 400°C at a cooling rate of 15°C / min, and then cooled to room temperature at a cooling rate of 40°C / min;

[0056] S3. The homogenized ingot was heated to 450°C and kept warm for 1.5h; the temperature of the extrusion cylinder, extrusion pad and extrusion die was 480°C; the extrusion ratio was 25; the extrusion speed was 5m / min;

[0057] S4. The obtained extruded profile is kept at 550°C for 60 minutes, then water-cooled to room temperature, and then water-cooled to room temperature and then aged at 175°C for 8 hours.

[0058] Comparative Example 1

[0059] This comparative example provides a 6 series aluminum alloy, with specific contents as follows: Mg content: 1.0wt.%, Si content: 1.2wt.%, Cu content: 0.2wt.%, Mn content: 0.5wt.%, Zn content: 0.4wt.%, Fe content: ≤0.1wt.%, Cr content: 0.2wt.%, and the remainder is Al. The sum of the weight percentages of the components is 100%, wherein Mn / Cr: 2.5.

[0060] This comparative example also provides a preparation method of a 6-series aluminum alloy, wherein the homogenization treatment is a single-stage homogenization treatment, specifically:

[0061] S1. The ingot is prepared by a semi-continuous ingot casting method, with a melting temperature of 740°C and a casting temperature of 730°C;

[0062] S2. The homogenization temperature is 550°C, and the temperature is maintained for 10 h. Then, the ingot is cooled to 400°C at a cooling rate of 15°C / min, and then the ingot is cooled to room temperature at a cooling rate of 40°C / min;

[0063] S3. The homogenized ingot was heated to 450°C and kept warm for 2h; the temperature of the extrusion cylinder, extrusion pad and extrusion die was 460°C; the extrusion ratio was 25; the extrusion speed was 4m / min;

[0064] S4. The obtained extruded profile is kept at 550°C for 40 minutes, then water-cooled to room temperature, and then water-cooled to room temperature and then aged at 175°C for 8 hours.

[0065] TEM photos of the homogenized state of Comparative Example 1 are as follows Figure 3 As shown, Figure 1 By comparison, we can find that Figure 3 The α-Al(FeMnCr)Si dispersed phase particles are larger in size and fewer in number. According to statistics, the dispersed phase area fraction is 2.1% and the size is 34.8nm.

[0066] Comparative Example 2

[0067] This comparative example prepares an aluminum alloy with a Mn content of 0.2wt.% and a Mn / Cr ratio of 1. The specific process is as follows:

[0068] This comparative example provides a 6 series aluminum alloy, with specific contents as follows: Mg content: 1.1wt.%, Si content: 1.2wt.%, Cu content: 0.2wt.%, Mn content: 0.2wt.%, Zn content: 0.4wt.%, Fe content: ≤0.1wt.%, Cr content: 0.2wt.%, and the remainder is Al. The sum of the weight percentages of the components is 100%, where Mn / Cr: 1.

[0069] This comparative example also provides a preparation method of a 6 series aluminum alloy, specifically:

[0070] S1. The ingot is prepared by a semi-continuous ingot casting method, with a melting temperature of 740°C and a casting temperature of 730°C;

[0071] S2. The primary homogenization temperature is 460°C, kept at this temperature for 8 hours, then heated to 550°C at a rate of 5°C / min, kept at this temperature for 8 hours, the ingot is first cooled to 400°C at a cooling rate of 15°C / min, and then the ingot is cooled to room temperature at a cooling rate of 40°C / min;

[0072] S3. The homogenized ingot was heated to 450°C and kept warm for 2h; the temperature of the extrusion cylinder, extrusion pad and extrusion die was 470°C; the extrusion ratio was 25; the extrusion speed was 4m / min;

[0073] S4. The obtained extruded profile is kept at 550°C for 40 minutes, then water-cooled to room temperature, and then water-cooled to room temperature and then aged at 175°C for 8 hours.

[0074] Comparative Example 3

[0075] This comparative example prepares an aluminum alloy with a Cu content of 0.5wt.%, and the specific process is as follows:

[0076] This comparative example provides a 6 series aluminum alloy, with specific contents as follows: Mg content: 1.0wt.%, Si content: 1.2wt.%, Cu content: 0.5wt.%, Mn content: 0.5wt.%, Zn content: 0.4wt.%, Fe content: ≤0.1wt.%, Cr content: 0.2wt.%, and the remainder is Al. The sum of the weight percentages of the components is 100%, wherein Mn / Cr: 2.5.

[0077] This comparative example also provides a preparation method of a 6 series aluminum alloy, specifically:

[0078] S1. The ingot is prepared by a semi-continuous ingot casting method, with a melting temperature of 740°C and a casting temperature of 730°C;

[0079] S2. The primary homogenization temperature is 470°C, kept at this temperature for 8 hours, then heated to 550°C at a rate of 5°C / min, kept at this temperature for 8 hours, the ingot is first cooled to 400°C at a cooling rate of 15°C / min, and then the ingot is cooled to room temperature at a cooling rate of 45°C / min;

[0080] S3. The homogenized ingot was heated to 450°C and kept warm for 2h; the temperature of the extrusion cylinder, extrusion pad and extrusion die was 480°C; the extrusion ratio was 25; the extrusion speed was 4m / min;

[0081] S4. The obtained extruded profile is kept at 550°C for 60 minutes, then water-cooled to room temperature, and then water-cooled to room temperature and then aged at 165°C for 10 hours.

[0082] Comparative Example 4

[0083] This comparative example prepares an aluminum alloy with a Mn / Cr ratio of 2. The specific process is as follows:

[0084] This comparative example provides a 6 series aluminum alloy, with specific contents as follows: Mg content: 0.9wt.%, Si content: 1.1wt.%, Cu content: 0.2wt.%, Mn content: 0.4wt.%, Zn content: 0.3wt.%, Fe content: ≤0.1wt.%, Cr content: 0.2wt.%, and the remainder is Al. The sum of the weight percentages of the components is 100%, wherein Mn / Cr: 2.

[0085] This comparative example also provides a preparation method of a 6 series aluminum alloy, specifically:

[0086] S1. The ingot is prepared by a semi-continuous ingot casting method, with a melting temperature of 740°C and a casting temperature of 730°C;

[0087] S2. The primary homogenization temperature is 460°C, kept at this temperature for 8 hours, then heated to 550°C at a rate of 5°C / min, kept at this temperature for 8 hours, the ingot is first cooled to 400°C at a cooling rate of 15°C / min, and then the ingot is cooled to room temperature at a cooling rate of 40°C / min;

[0088] S3. The homogenized ingot was heated to 450°C and kept warm for 2h; the temperature of the extrusion cylinder, extrusion pad and extrusion die was 470°C; the extrusion ratio was 25; the extrusion speed was 4m / min;

[0089] S4. The obtained extruded profile is kept at 550°C for 40 minutes, then water-cooled to room temperature, and then water-cooled to room temperature and then aged at 175°C for 8 hours.

[0090] Comparative Example 5

[0091] This comparative example prepares an aluminum alloy with a Zn content of 0.10wt.%, and the specific process is as follows:

[0092] This comparative example provides a 6 series aluminum alloy, with specific contents as follows: Mg content: 1.0wt.%, Si content: 1.1wt.%, Cu content: 0.2wt.%, Mn content: 0.5wt.%, Zn content: 0.10wt.%, Fe content: ≤0.1wt.%, Cr content: 0.2wt.%, and the remainder is Al. The sum of the weight percentages of the components is 100%, wherein Mn / Cr: 2.5.

[0093] This comparative example also provides a preparation method of a 6 series aluminum alloy, specifically:

[0094] S1. The ingot is prepared by a semi-continuous ingot casting method, with a melting temperature of 740°C and a casting temperature of 730°C;

[0095] S2. The primary homogenization temperature is 460°C, kept at this temperature for 8 hours, then heated to 550°C at a rate of 5°C / min, kept at this temperature for 8 hours, the ingot is first cooled to 400°C at a cooling rate of 15°C / min, and then the ingot is cooled to room temperature at a cooling rate of 40°C / min;

[0096] S3. The homogenized ingot was heated to 450°C and kept warm for 2h; the temperature of the extrusion cylinder, extrusion pad and extrusion die was 470°C; the extrusion ratio was 25; the extrusion speed was 4m / min;

[0097] S4. The obtained extruded profile is kept at 550°C for 40 minutes, then water-cooled to room temperature, and then water-cooled to room temperature and then aged at 175°C for 8 hours.

[0098] Comparative Example 6

[0099] This comparative example prepares an aluminum alloy with a Zn content of 0.65wt.%, and the specific process is as follows:

[0100] This comparative example provides a 6 series aluminum alloy, with specific contents as follows: Mg content: 0.9wt.%, Si content: 1.1wt.%, Cu content: 0.2wt.%, Mn content: 0.5wt.%, Zn content: 0.65wt.%, Fe content: ≤0.1wt.%, Cr content: 0.2wt.%, and the remainder is Al. The sum of the weight percentages of the components is 100%, wherein Mn / Cr: 2.5.

[0101] This comparative example also provides a preparation method of a 6 series aluminum alloy, specifically:

[0102] S1. The ingot is prepared by a semi-continuous ingot casting method, with a melting temperature of 740°C and a casting temperature of 730°C;

[0103] S2. The primary homogenization temperature is 460°C, kept at this temperature for 8 hours, then heated to 550°C at a rate of 5°C / min, kept at this temperature for 8 hours, the ingot is first cooled to 400°C at a cooling rate of 15°C / min, and then the ingot is cooled to room temperature at a cooling rate of 40°C / min;

[0104] S3. The homogenized ingot was heated to 450°C and kept warm for 2h; the temperature of the extrusion cylinder, extrusion pad and extrusion die was 470°C; the extrusion ratio was 25; the extrusion speed was 4m / min;

[0105] S4. The obtained extruded profile is kept at 550°C for 40 minutes, then water-cooled to room temperature, and then water-cooled to room temperature and then aged at 175°C for 8 hours.

[0106] Test example

[0107] The performance test results of the embodiments and comparative examples are shown in Table 1:

[0108] The detection methods used are:

[0109] Room temperature tensile properties: in accordance with GBT228.1-2010 Metallic material tensile test Part 1: Room temperature test method. Intergranular corrosion properties: in accordance with GB / T7998-2005 Aluminum alloy intergranular corrosion determination method.

[0110] Table 1 Comparison of mechanical properties and intergranular corrosion performance of different cases

[0111]

[0112]

[0113] Test standard:

[0114] From the test results in Table 1, it can be seen that in Comparative Example 1, after single-stage homogenization treatment, the size of the α-Al(FeMnCr)Si dispersed phase is larger and the number is smaller, as shown in FIG. Figure 1 and Figure 3 , which leads to a decrease in the pinning effect on the grain boundaries and coarsening of the grain size after solution aging, which ultimately affects the mechanical and corrosion properties of the alloy.

[0115] It can be seen from the test results in Table 1 that in Comparative Example 2, the Mn content and the Mn / Cr ratio are too low. After the alloy is subjected to the double-stage homogenization treatment, the amount of the α-Al(FeMnCr)Si dispersed phase is reduced, which affects the mechanical properties of the alloy.

[0116] It can be seen from the test results in Table 1 that in Comparative Example 3, too high a Cu content can improve the mechanical properties, but a continuous Cu-rich film will be formed on the grain boundary, which seriously affects the intergranular corrosion performance of the alloy.

[0117] It can be seen from the test results in Table 1 that in Comparative Example 4, the Mn / Cr ratio is too low, the amount of α-Al(FeMnCr)Si dispersed phase is reduced, resulting in coarse grains and reduced mechanical properties.

[0118] From the test results in Table 1, it can be seen that in Comparative Example 5, the Zn content is too low, which has little effect on the formation of Mg-Si atomic clusters. After the aging is completed, the amount of β" phase is small and the precipitation strengthening effect is reduced.

[0119] It can be seen from the test results in Table 1 that in Comparative Example 6, the Zn content is too high, which can form a T phase in the matrix to improve the mechanical properties, but also form a coarse Zn-rich phase at the grain boundary, ultimately affecting the intergranular corrosion performance.

[0120] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. An aluminum alloy, characterized in that: Calculated by weight percentage, the invention comprises the following components: Cu 0.1-0.2wt.%, Mn 0.4-0.5wt.%, Zn 0.2-0.5wt.%, Cr 0.15-0.2wt.%, wherein the weight ratio of Mn to Cr is 2.5-3.

2. The aluminum alloy according to claim 1, characterized in that The components of the aluminum alloy also include: Mg 0.9-1.2wt.%.

3. The aluminum alloy according to claim 1, characterized in that The components of the aluminum alloy also include: Si 1.0-1.4wt.%.

4. A method for preparing an aluminum alloy as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: S1: melting and casting an aluminum ingot and a raw material containing the aluminum alloy component to obtain an aluminum alloy ingot; S2: homogenizing the aluminum alloy ingot obtained in step S1; S3: extruding the aluminum alloy ingot obtained in step S2 to obtain an aluminum alloy extruded profile; S4: The extruded profile is subjected to solution quenching and then aging treatment.

5. The method for preparing the aluminum alloy according to claim 4, characterized in that: The melting temperature is 730-750°C; and / or the casting temperature is 730-740°C.

6. The method for preparing the aluminum alloy according to claim 4, characterized in that: The homogenization step comprises: heating the aluminum alloy ingot to 460-480°C for 6-8h, then heating to 530-550°C at a rate of 5-8°C / min, keeping the temperature for 8-12h, cooling down to 380-400°C at a cooling rate of no higher than 15°C / min, and then cooling down to room temperature at a cooling rate of no lower than 35°C / min.

7. The method for preparing the aluminum alloy according to claim 4, characterized in that: The extrusion temperature is 450-470° C., and the extrusion time is 1-2 hours.

8. The method for preparing an aluminum alloy according to claim 4, characterized in that: The temperature of the solid solution quenching is 530-550° C., and the time of the solid solution quenching is 40-80 min.

9. The method for preparing an aluminum alloy according to claim 4, characterized in that: The temperature of the aging treatment is 165-175° C., and the time of the aging treatment is 6-10 hours.

10. Use of the aluminum alloy according to any one of claims 1 to 3 in transportation vehicles.

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