Aluminum alloy treatment method

Abstract

The invention relates to the technical field of aluminum alloy treatment, in particular to an aluminum alloy treatment method. The invention provides an aluminum alloy treatment method. The aluminum alloy treatment method comprises the steps that first-stage electric pulse treatment, second-stage direct current compensation treatment, third-stage electric pulse treatment and fourth-stage direct current compensation treatment are sequentially conducted on aluminum alloy; wherein in each stage of treatment, the directions of currents passing through the aluminum alloy are consistent, the treatment time of the first-stage electric pulse treatment or the third-stage electric pulse treatment is 1-2 s, and the treatment time of the second-stage direct current compensation treatment or the fourth-stage direct current compensation treatment is 1-3 h; and naturally cooling to room temperature after each stage of treatment is finished. According to the treatment method, an electric pulse and direct current compensation cross treatment mode is adopted, the treatment time is shortened to be not more than 5 h, the treatment efficiency is greatly improved, the energy loss is reduced, the mechanical strength and corrosion resistance of the aluminum alloy are improved at the same time, and the treatment method has huge potential in the metal treatment industry.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy processing, and in particular to an aluminum alloy processing method. Background Art

[0002] 7 series aluminum alloy has the characteristics of high specific strength, good processing performance, excellent thermal and electrical conductivity, etc. It is widely used in various vehicle bodies including automobiles. When used as a vehicle body, it is required to have excellent corrosion resistance, but there is a contradiction between its strength and corrosion resistance that is difficult to improve at the same time. This contradiction seriously limits the development and application of 7 series aluminum alloy. The contradiction between strength and corrosion resistance has always been the main factor restricting its further development and application.

[0003] At present, heat treatment is often used to balance the contradiction between the two. However, the traditional heat treatment process completely relies on the heat treatment furnace. It is not only difficult to accurately control the temperature, but also the process is extremely complex and time-consuming, resulting in low processing efficiency and serious energy waste. Patent CN 116536598 A discloses a heat treatment method for 7475 aluminum alloy to solve the contradiction between strength and corrosion resistance. The method relies on heat treatment furnace for heat treatment, and the treatment time is as long as 49h; Patent CN116043146A discloses a method for improving the intergranular corrosion resistance of aluminum alloy and the aluminum alloy obtained. The method combines heat treatment, natural aging treatment and pulse current treatment, and the cumulative treatment time exceeds 95h; Patent CN104694865A discloses an electric pulse regression treatment method for aluminum alloy. The first step of the method relies on the heat treatment furnace for solid solution treatment, and it requires natural aging for 10 days, which increases the time cost.

[0004] Electric current treatment has the characteristics of high efficiency, low energy consumption, no secondary pollution, wide applicability, and strong controllability, and is a feasible alternative to traditional heat treatment methods. However, the current electric current treatment method is still partially dependent on heat treatment, that is, it still needs to be combined with heat treatment to obtain a more ideal result, and it has not completely gotten rid of the limitations of the heat treatment furnace; in addition, although some studies have achieved pure electric current treatment of aluminum alloys, the treatment time is still more than 8 hours. Summary of the invention

[0005] In view of this, the present invention provides an aluminum alloy processing method. The processing method can improve the strength and corrosion resistance of aluminum alloy plates in a short time (5 hours), breaking through the technical bottleneck of aluminum alloy plate performance regulation, and can also be used in other metal material processing fields, with great promotion prospects and significant economic benefits.

[0006] To solve the above technical problems, the first aspect of the present invention provides an aluminum alloy processing method, comprising: subjecting the aluminum alloy to sequential electric pulse treatment, secondary DC compensation treatment, tertiary electric pulse treatment and quaternary DC compensation treatment; wherein, in each stage of treatment, the direction of the current passing through the aluminum alloy is consistent, the processing time of the first-level electric pulse treatment or the third-level electric pulse treatment is 1 to 2 seconds, and the processing time of the second-level DC compensation treatment or the fourth-level DC compensation treatment is 1 to 3 hours; after each stage of treatment is completed, the aluminum alloy is naturally cooled to room temperature.

[0007] The aluminum alloy processing method provided by the present invention adopts pulse current and DC compensation cross processing to replace the traditional muffle furnace heating treatment, so that the material precipitate phase can be dissolved back more quickly, and after the three-level electric pulse treatment, the precipitation speed of the precipitate phase during the four-level DC compensation treatment can be accelerated, and the processing time can be significantly shortened. The processing method can simultaneously improve the strength and corrosion resistance of the material, and can also greatly reduce the energy consumption in the production process, improve production efficiency, and has great practical application significance.

[0008] In combination with the first aspect, the total processing time of the first-level electric pulse treatment, the second-level DC compensation treatment, the third-level electric pulse treatment and the fourth-level DC compensation treatment does not exceed 5 hours.

[0009] The total processing time of the processing method provided by the present invention does not exceed 5 hours, and the obtained aluminum alloy has better tensile strength and corrosion resistance than the aluminum alloy obtained by the existing heat treatment method, which greatly saves the processing time and improves the processing efficiency.

[0010] In combination with the first aspect, the direction of the current passing through the aluminum alloy is consistent: the two ends of the aluminum alloy to be processed are marked as the first end and the second end, respectively, wherein the first end is connected to the positive pole of the power supply, and the second end is connected to the negative pole of the power supply.

[0011] In combination with the first aspect, in the first-stage electric pulse treatment, the 2 The treatment was carried out at a current density of 1 to 2 seconds, wherein the current frequency was 5 to 10 Hz, the positive pulse width was 0.04 to 0.1 s, and the duty cycle was 40% to 60%. The current density, treatment time, current frequency, positive pulse width, and duty cycle within this range can fully dissolve the precipitated phase.

[0012] Preferably, in the first-stage electric pulse treatment, the 2 The treatment was carried out at a current density of 1s.

[0013] Preferably, in the primary electric pulse treatment, the current frequency is 10 Hz and the positive pulse width is 0.05 s.

[0014] In combination with the first aspect, in the secondary DC compensation process, at 20~30 A / mm 2 The material is treated at a current density of 1.5 to 2 hours. This current density and treatment time can cause the material to precipitate a fine and evenly distributed precipitate phase.

[0015] Preferably, in the secondary DC compensation process, at 25 A / mm 2 The treatment was carried out at a current density of 1.5 h.

[0016] In combination with the first aspect, in the three-stage electric pulse treatment, the 2 The treatment is carried out at a current density of 1 to 2 seconds, wherein the current frequency is 5 to 10 Hz, the positive pulse width is 0.04 to 0.1 s, and the duty cycle is 40% to 60%. The current density, treatment time, current frequency, positive pulse width, and duty cycle within this range can cause the precipitated phase in the crystal to dissolve back and become a fine precipitated phase.

[0017] Preferably, at 200A / mm 2 The treatment was carried out at a current density of 1s.

[0018] In combination with the first aspect, in the four-stage DC compensation process, at 25~35 A / mm 2 The treatment was carried out at a current density of 2.5-3h. This current density and treatment time can make the grain boundary precipitation phase more uniform and dense.

[0019] A second aspect of the present invention provides a high-strength, corrosion-resistant 7-series aluminum alloy using the aluminum alloy processing method described above.

[0020] The 7 series aluminum alloy is treated by the four-level electric pulse and DC compensation cross-treatment method provided by the present invention, which can simultaneously improve the mechanical strength and corrosion resistance of the 7 series aluminum alloy and greatly shorten the treatment time, and has good application prospects.

[0021] A third aspect of the present invention provides an application of the high-strength, corrosion-resistant 7-series aluminum alloy in the fields of automobile manufacturing, shipbuilding, aerospace, or rail transportation.

[0022] Beneficial effects obtained by the present invention: The aluminum alloy processing method provided by the present invention has different processing time, current frequency, current density and other parameters for two electric pulse processing and two DC compensation processing, and the above parameters can be autonomously regulated, thereby realizing precise regulation of the distribution of the precipitated phase, and improving both mechanical properties and corrosion properties. Moreover, the present invention adopts the method of cross-processing of electric pulse and DC compensation to shorten the processing time to no more than 5 hours, greatly improving the processing efficiency, reducing energy loss, and at the same time improving the mechanical strength and corrosion resistance of the aluminum alloy. The mechanical properties and corrosion resistance of the aluminum alloy obtained under the condition of greatly shortened processing time are better than those of the aluminum alloy obtained according to the existing method, and has great potential in the metal processing industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 1 is a precipitation phase distribution diagram of the aluminum alloy in Example 1 of the present invention before and after treatment, wherein (a) is a precipitation phase distribution diagram of the 7475 aluminum alloy before treatment, and (b) is a precipitation phase distribution diagram of the 7475 aluminum alloy after treatment obtained in Example 1 of the present invention; Figure 2 The hardness variation diagram of the aluminum alloys obtained in Examples 1 to 2 of the present invention and Comparative Example 1 and the corresponding aluminum alloys before treatment; Figure 3 The stress-strain curves of the aluminum alloys obtained in Examples 1 to 2 of the present invention and Comparative Example 1 and the corresponding aluminum alloys before treatment; Figure 4 This is a graph showing the corrosion resistance of the 7475 aluminum alloy obtained in Example 1 of the present invention and the 7475 aluminum alloy before treatment; Figure 5 This is a graph showing the corrosion resistance of the 7N01 aluminum alloy obtained in Example 2 of the present invention and the 7N01 aluminum alloy before treatment; Figure 6 This is a graph showing the change in corrosion resistance of the 7475 aluminum alloy obtained in Comparative Example 1 of the present invention and the 7475 aluminum alloy before treatment. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following is a detailed description of the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] 7 series aluminum alloy is widely used in automobiles and various vehicle bodies, but the contradiction between its strength and corrosion resistance seriously limits its development and application. In view of the fact that the current method for solving the contradiction between the strength and corrosion resistance of aluminum alloys needs to rely on heat treatment furnaces and / or requires a long processing time, the present invention provides a four-level electric pulse and DC compensation cross-processing method, which adopts a cross-processing mode of electric pulse processing and DC compensation, does not require cutting processing, and can achieve the simultaneous improvement of the strength and corrosion resistance of 7 series aluminum alloy within 5 hours, significantly shortens the processing time, and significantly reduces energy consumption.

[0026] The aluminum alloy processing method provided by the present invention is described in more detail below through specific examples and comparative examples.

[0027] Example 1 This embodiment provides a method for treating 7475 aluminum alloy, comprising the following steps: S1, primary electric pulse treatment: mark the two ends of 7475 aluminum alloy as end A and end B respectively, connect end A to the positive pole of the power supply, and end B to the negative pole of the power supply, at 250 A / mm 2 The pulse current was treated for 1s at a current density of , wherein the pulse current frequency was 10 Hz, the positive pulse width was 0.05s, the duty cycle was 50%, and the mixture was naturally cooled to room temperature; S2, secondary DC compensation treatment: The A end of the aluminum alloy cooled to room temperature in S1 is connected to the positive pole of the power supply, and the B end is connected to the negative pole of the power supply. 2 DC compensation treatment was performed at a current density of 1.5 h, and then naturally cooled to room temperature; S3, three-level electric pulse treatment: The A end of the aluminum alloy cooled to room temperature in S2 is connected to the positive electrode of the power supply, and the B end is connected to the negative electrode of the power supply. 2 The pulse current was treated for 1s at a current density of , wherein the pulse current frequency was 10 Hz, the positive pulse width was 0.04s, the duty cycle was 40%, and the mixture was naturally cooled to room temperature; S4, four-level DC compensation treatment: The A end of the aluminum alloy cooled to room temperature in S3 is connected to the positive electrode of the power supply, and the B end is connected to the negative electrode of the power supply. 2 The alloy was treated with direct current for 2.5 h at a current density of , and then naturally cooled to room temperature to obtain a 7475 aluminum alloy with high strength and high corrosion resistance.

[0028] Example 2 This embodiment provides a method for treating 7N01 aluminum alloy, comprising the following steps: S1, primary electric pulse treatment: mark the two ends of 7N01 aluminum alloy as A and B respectively, connect A to the positive pole of the power supply, and connect B to the negative pole of the power supply. 2 The pulse current was treated for 2s at a current density of , wherein the pulse current frequency was 10 Hz, the positive pulse width was 0.05s, the duty cycle was 55%, and the mixture was naturally cooled to room temperature; S2, secondary DC compensation treatment: The A end of the aluminum alloy cooled to room temperature in S1 is connected to the positive pole of the power supply, and the B end is connected to the negative pole of the power supply. 2 DC current treatment was performed at a current density of 2 h for DC compensation treatment, and then naturally cooled to room temperature; S3, three-level electric pulse treatment: The A end of the aluminum alloy cooled to room temperature in S2 is connected to the positive electrode of the power supply, and the B end is connected to the negative electrode of the power supply. 2 The pulse current was treated for 1s at a current density of , wherein the pulse current frequency was 10 Hz, the positive pulse width was 0.06s, the duty cycle was 60%, and the mixture was naturally cooled to room temperature; S4, four-level DC compensation treatment: The A end of the aluminum alloy cooled to room temperature in S3 is connected to the positive electrode of the power supply, and the B end is connected to the negative electrode of the power supply. 2 The alloy was treated with direct current for 2.5 h at a current density of , and then naturally cooled to room temperature to obtain a 7N01 aluminum alloy with high strength and high corrosion resistance.

[0029] Example 3 This embodiment provides a method for treating 7475 aluminum alloy, comprising the following steps: S1, primary electric pulse treatment: mark the two ends of 7475 aluminum alloy as end A and end B respectively, connect end A to the positive pole of the power supply, and end B to the negative pole of the power supply, at 240 A / mm 2 The pulse current was treated for 1s at a current density of , wherein the pulse current frequency was 10 Hz, the positive pulse width was 0.05s, the duty cycle was 50%, and the mixture was naturally cooled to room temperature; S2, secondary DC compensation treatment: The A end of the aluminum alloy cooled to room temperature in S1 is connected to the positive pole of the power supply, and the B end is connected to the negative pole of the power supply. 2 DC compensation treatment was performed at a current density of 1.5 h, and then naturally cooled to room temperature; S3, three-level electric pulse treatment: The A end of the aluminum alloy cooled to room temperature in S2 is connected to the positive electrode of the power supply, and the B end is connected to the negative electrode of the power supply. 2 The pulse current was treated for 2s at a current density of , wherein the pulse current frequency was 10 Hz, the positive pulse width was 0.05s, the duty cycle was 50%, and the mixture was naturally cooled to room temperature; S4, four-level DC compensation treatment: The A end of the aluminum alloy cooled to room temperature in S3 is connected to the positive electrode of the power supply, and the B end is connected to the negative electrode of the power supply. 2 The alloy was treated with direct current for 3 h at a current density of , and then naturally cooled to room temperature to obtain a 7475 aluminum alloy with high strength and high corrosion resistance.

[0030] Example 4 This embodiment provides a method for treating 7475 aluminum alloy, comprising the following steps: S1, primary electric pulse treatment: mark the two ends of 7475 aluminum alloy as A and B respectively, connect A to the positive pole of the power supply, and connect B to the negative pole of the power supply. 2 The pulse current was treated for 1s at a current density of , wherein the pulse current frequency was 10 Hz, the positive pulse width was 0.05s, the duty cycle was 50%, and the mixture was naturally cooled to room temperature; S2, secondary DC compensation treatment: The A end of the aluminum alloy cooled to room temperature in S1 is connected to the positive pole of the power supply, and the B end is connected to the negative pole of the power supply. 2 DC current treatment was performed at a current density of 2 h for DC compensation treatment, and then naturally cooled to room temperature; S3, three-level electric pulse treatment: The A end of the aluminum alloy cooled to room temperature in S2 is connected to the positive electrode of the power supply, and the B end is connected to the negative electrode of the power supply. 2 The pulse current was treated for 1s at a current density of , wherein the pulse current frequency was 10 Hz, the positive pulse width was 0.05s, the duty cycle was 50%, and the mixture was naturally cooled to room temperature; S4, four-level DC compensation treatment: The A end of the aluminum alloy cooled to room temperature in S3 is connected to the positive electrode of the power supply, and the B end is connected to the negative electrode of the power supply. 2 The alloy was treated with direct current for 2 h at a current density of , and then naturally cooled to room temperature to obtain a 7475 aluminum alloy with high strength and high corrosion resistance.

[0031] Comparative Example 1 This comparative example provides a method for treating 7475 aluminum alloy, comprising the following steps: S1, primary electric pulse treatment: the specific steps are the same as step S1 of embodiment 1; S2, secondary DC compensation treatment: The A end of the aluminum alloy cooled to room temperature in S1 is connected to the positive pole of the power supply, and the B end is connected to the negative pole of the power supply. 2 The DC compensation treatment was carried out by direct current treatment at a current density of 4 h, and then naturally cooled to room temperature.

[0032] Comparative Example 2 In this comparative example, 7475 aluminum alloy is treated according to the existing treatment method combining electric pulse and heat treatment, including the following steps: S1, primary electric pulse treatment: mark the two ends of 7475 aluminum alloy as end A and end B respectively, connect end A to the positive pole of the power supply, and end B to the negative pole of the power supply. 2 The pulse current treatment was carried out for 3s at a current density of , wherein the pulse current frequency was 10 Hz, the positive pulse width was 0.05s, the duty cycle was 50%, and water quenching was performed immediately after the electric pulse ended; S2. Heat treatment: The aluminum alloy cooled in S1 is placed in a muffle furnace and artificially aged at 180°C for 8 hours, and then air-cooled to room temperature.

[0033] Test Example 1 The morphology of the 7475 aluminum alloy before treatment and the 7475 aluminum alloy obtained in Example 1 was analyzed, and the distribution diagram of the precipitated phase is shown as follows: Figure 1 As shown, it can be seen that the precipitated phase at the grain boundary of the 7475 alloy obtained in Example 1 after treatment is significantly increased, which is beneficial to improving the corrosion resistance of the material.

[0034] Test Example 2 The aluminum alloys obtained in Examples 1-2, Comparative Example 1, and the corresponding aluminum alloys without any treatment (before treatment) were tested for hardness, mechanical properties, and corrosion resistance. The results are as follows: Figures 2 to 6 shown.

[0035] Depend on Figure 2 It can be seen that the hardness of the 7475 aluminum alloy obtained in Example 1 is slightly improved compared with the corresponding hardness before treatment, and the average hardness of the area within 15 mm from the center of the sample is increased from 171.3 HV before treatment to 177.4 HV, an increase of 3.6%; the average hardness of the 7N01 aluminum alloy obtained in Example 2 within 15 mm from the center of the sample is increased from 106.5 HV before treatment to 117.2 HV, an increase of 10%; while the average hardness of the aluminum alloy obtained in Comparative Example 1 using secondary treatment in the area within 15 mm from the center of the sample is not only not improved, but is significantly decreased (decreased by about 11%).

[0036] Depend on Figure 3 It can be seen that the tensile strength of the 7475 aluminum alloy obtained in Example 1 is increased from 501 MPa before treatment to 531.7 MPa, an increase of 6.1%, and the yield strength is improved; the tensile strength of the 7N01 aluminum alloy obtained in Example 2 is increased from 310 MPa before treatment to 330 MPa, an increase of 6.5%, and the yield strength is also improved; while the yield strength and tensile strength of the aluminum alloy obtained in Comparative Example 1 using secondary treatment are significantly reduced.

[0037] Depend on Figures 4 to 6 It can be seen that the corrosion potential of the 7475 aluminum alloy obtained in Example 1 changed from -1.272 V before treatment to -1.233 V, and the corrosion current changed from 28 μA / cm 2 Reduced to 5.9 μA / cm 2 , the corrosion current decreased by 79%, indicating that the corrosion resistance was significantly improved; the corrosion potential of the 7N01 aluminum alloy obtained in Example 2 changed from -1.321 V before treatment to -1.264 V, and the corrosion current changed from 87.3 μA / cm before treatment 2 Reduced to 33.1 μA / cm 2 , decreased by about 62%, indicating that the corrosion resistance is significantly improved; the corrosion potential of the aluminum alloy obtained in Comparative Example 1 changed from -1.272V before treatment to -1.252V, and the corrosion current increased from 28 μA / cm 2 Reduced to 15.5 μA / cm 2 , reduced by about 45%.

[0038] The performance test results of the aluminum alloys obtained in Comparative Example 2 and Example 1 and the 7475 aluminum alloy before treatment are shown in Table 1.

[0039] Table 1 .

[0040] It can be seen from Table 1 that, compared with the 7475 aluminum alloy without any treatment, the hardness, tensile strength, yield strength and corrosion resistance of the aluminum alloys obtained in Example 1 and Comparative Example 2 are improved to varying degrees. The performance of the aluminum alloy obtained in Example 1 treated according to the treatment method provided by the present invention is better than that of the aluminum alloy obtained in Comparative Example 2 treated according to the prior art, and the time is shortened by nearly 40%, and the treatment efficiency is significantly improved.

[0041] In summary, it can be seen that after treating the 7 series aluminum alloy according to the treatment method provided by the present invention, the hardness, tensile strength and corrosion resistance of the aluminum alloy can be improved at the same time, and the various properties of the obtained aluminum alloy are better than those of the existing aluminum alloy obtained by long-term heat treatment. The treatment method can be completed within 5 hours, which significantly shortens the treatment time and significantly reduces energy consumption.

[0042] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for treating an aluminum alloy, characterized in that: include: The aluminum alloy is sequentially subjected to a first-level electric pulse treatment, a second-level DC compensation treatment, a third-level electric pulse treatment, and a fourth-level DC compensation treatment; Among them, in each level of treatment, the direction of the current passing through the aluminum alloy is consistent, the processing time of the first-level electric pulse treatment or the third-level electric pulse treatment is 1~2s, and the processing time of the second-level DC compensation treatment or the fourth-level DC compensation treatment is 1~3h; after each level of treatment is completed, it is naturally cooled to room temperature.

2. The aluminum alloy processing method according to claim 1, characterized in that: The total processing time of the first-level electric pulse treatment, the second-level DC compensation treatment, the third-level electric pulse treatment and the fourth-level DC compensation treatment does not exceed 5 hours.

3. The aluminum alloy processing method according to claim 1, characterized in that: The direction of the current passing through the aluminum alloy is consistent: the two ends of the aluminum alloy to be processed are marked as a first end and a second end respectively, wherein the first end is connected to the positive electrode of the power supply, and the second end is connected to the negative electrode of the power supply.

4. The aluminum alloy processing method according to claim 1, characterized in that: In the first-level electric pulse treatment, the 2 The current density is 1~2s; the current frequency is 5~10 Hz, the positive pulse width is 0.04~0.1 s, and the duty cycle is 40%~60%.

5. The aluminum alloy processing method according to claim 1, characterized in that: In the secondary DC compensation process, the current is between 20 and 30 A / mm. 2 Treat at a current density of 1.5~2h.

6. The aluminum alloy processing method according to claim 1, characterized in that: In the three-stage electric pulse treatment, the 2 The current density is 1~2s; the current frequency is 5~10 Hz, the positive pulse width is 0.04~0.1 s, and the duty cycle is 40%~60%.

7. The aluminum alloy processing method according to claim 1, characterized in that: In the four-stage DC compensation process, the 2 Treat at a current density of 2.5~3h.

8. A high-strength, corrosion-resistant 7 series aluminum alloy, characterized in that: The aluminum alloy processing method according to any one of claims 1 to 7 is adopted.

9. Use of the high-strength, corrosion-resistant 7-series aluminum alloy according to claim 8 in the fields of automobile manufacturing, shipbuilding, aerospace, or rail transportation.

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