A method for improving the creep age forming performance of aluminum alloy

Abstract

The present invention discloses a method for improving the creep age forming performance of aluminum alloy. The characteristics are as follows: first, the aluminum alloy blank is solution-treated and then water-quenched to obtain a semi-finished aluminum alloy product; then, the quenched semi-finished aluminum alloy product is subjected to aging treatment; then, the aged semi-finished aluminum alloy product is subjected to high-speed impact pre-deformation; finally, the semi-finished aluminum alloy product after high-speed impact pre-deformation is subjected to creep age forming to obtain a finished aluminum alloy product. The advantages are that before the creep age forming of the semi-finished aluminum alloy product, high-speed impact pre-deformation treatment is carried out, so that the internal grains of the aluminum alloy are refined, and at the same time, dislocation microstructures can be introduced into the aluminum alloy matrix, effectively improving the creep amount of the aluminum alloy, promoting the dislocation movement in the aluminum alloy, accelerating the precipitation of the precipitation phase, improving the strength and forming performance of the finished aluminum alloy product, facilitating the simultaneous forming and property improvement of the aluminum alloy, and saving energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloy forming, and particularly relates to a method for improving the creep age forming performance of aluminum alloy. Background Art

[0002] Due to advantages such as low density, high specific strength, good thermal and electrical conductivity, and easy forming and processing, aluminum alloys are widely used in lightweight structures or functional materials for aerospace, military equipment, automobiles, power cables, etc. As heat-treatable aluminum alloys, their strength increases after artificial aging. However, the high strength and high ductility (i.e., plasticity) of aluminum alloys are mutually exclusive, which means that increasing their strength will lead to a corresponding decrease in ductility. Therefore, it is crucial to combine strength and plasticity during the forming process.

[0003] Currently, creep age forming technology has become an important technology for forming aluminum alloy integral panels due to advantages such as small residual stress and simultaneous forming and strengthening. Creep age forming technology can improve macro and micro properties while achieving precise forming, and is suitable for the forming of aluminum alloy components that can be age-strengthened.

[0004] However, with the trend that structural components used in the future aerospace field will be more complex, the relatively low formability of aluminum alloys at room temperature is considered to limit their further application. Continuing to use traditional cold forming technologies (such as single tension forming, double tension forming, roll bending forming, etc.) often results in forming defects such as buckling and cracking. At the same time, traditional cold forming technologies perform forming and age strengthening treatments separately, with more forming processes, lower efficiency, and poorer surface quality of the formed parts. Creep age forming technology synchronizes the creep forming and age strengthening treatments of materials, significantly increasing the forming accuracy and efficiency of components. However, compared with traditional 2-series aluminum alloys (such as 2219 aluminum alloy), aerospace high-strength lightweight aluminum alloys (aluminum-lithium alloys, 7-series aluminum alloys) have small creep amounts and low forming efficiency of components, severely restricting the application of aerospace high-strength lightweight aluminum alloys. In summary, it is very important to increase the creep amount during the creep age forming process of aluminum alloys (aluminum-lithium alloys, 7-series aluminum alloys) and the mechanical properties after creep aging. Therefore, there is an urgent need for an aluminum alloy creep age forming method that can simultaneously obtain high material strength and good forming performance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for improving the creep age forming performance of aluminum alloy, which can effectively increase the creep amount of aluminum alloy, while improving the strength and forming performance of the aluminum alloy finished product, facilitating the collaborative manufacturing of formability of aluminum alloy, and saving energy consumption.

[0006] The technical solution adopted by the present invention to solve the above technical problem is: a method for improving the creep age forming performance of aluminum alloy, including the following specific steps:

[0007] (1) Solutionize the aluminum alloy blank and then perform water quenching to obtain a semi-finished aluminum alloy product;

[0008] (2) Perform aging treatment on the quenched semi-finished aluminum alloy product;

[0009] (3) Perform high-speed impact pre-deformation on the semi-finished aluminum alloy product after aging treatment;

[0010] (4) Perform creep aging forming on the semi-finished aluminum alloy product after high-speed impact pre-deformation to obtain a finished aluminum alloy product.

[0011] Furthermore, in step (2), the aging treatment temperature is 60 - 250 °C, and the aging time is 0.5 - 20 h.

[0012] Furthermore, in step (2), the aging treatment is 1 - 4 level aging heat treatment.

[0013] Furthermore, in step (3), the strain rate of high-speed impact is 100 - 6000 s -1 , and the deformation amount is 0.1 - 15%.

[0014] Furthermore, in step (4), when performing creep aging forming on the semi-finished aluminum alloy product, control the creep aging temperature to be 60 - 300 °C, the time to be 2 - 20 h, and the creep stress to be 50 - 650 Mpa.

[0015] Furthermore, the aluminum alloy blank is obtained by hot rolling.

[0016] Furthermore, the aluminum alloy is an aluminum-lithium alloy, a 2-series aluminum alloy, or a 7-series aluminum alloy.

[0017] Compared with the prior art, the advantages of the present invention are as follows: Before performing creep aging forming on the semi-finished aluminum alloy product, high-speed impact pre-deformation treatment is carried out, which refines the internal grains of the aluminum alloy, and at the same time, dislocation microstructures can be introduced into the aluminum alloy matrix, effectively improving the creep amount of the aluminum alloy, promoting the dislocation movement in the aluminum alloy, accelerating the precipitation of precipitated phases, improving the strength and formability of the finished aluminum alloy product, facilitating the collaborative manufacturing of the formability of the aluminum alloy, and saving energy consumption. Through experimental verification, under the same creep aging temperature and time, compared with the aluminum alloy after conventional slow-rate pre-deformation in the traditional T3 and T4 states, the creep amount of the finished aluminum alloy product formed by the present invention is increased by 20 - 130%, the ductility is improved, the yield strength is increased by 15 - 35%, and the tensile strength is increased by 15 - 35%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the process flow chart of the present invention;

[0019] Figure 2 Schematic diagram for comparing creep curves of aluminum alloy bars in Embodiments 1-3 and Comparative Examples 1 and 2 of the present invention;

[0020] Figure 3 Schematic diagram for comparing creep curves of aluminum alloy bars in Embodiment 4 and Comparative Examples 3 and 4 of the present invention;

[0021] Figure 4 Schematic diagram for comparing mechanical properties of aluminum alloy bars in Embodiments 1-3 and Comparative Examples 1 and 2 of the present invention;

[0022] Figure 5 Schematic diagram for comparing mechanical properties of aluminum alloy bars in Embodiment 4 and Comparative Examples 3 and 4 of the present invention. Detailed implementation manners

[0023] The present invention will be further described in detail below with reference to the embodiments in the drawings.

[0024] The aluminum alloy billets used in the embodiments and comparative examples are commercial aluminum alloys: 2195 aluminum alloy (aluminum-lithium alloy) and 7075 aluminum alloy.

[0025] Embodiment 1: A method for improving the creep age forming performance of aluminum alloy, including the following specific steps:

[0026] (1), Put the 2195 aluminum alloy into an air-circulating resistance furnace, perform solution treatment at a temperature of 510 °C for 30 min, take it out and perform water quenching to obtain an aluminum alloy bar;

[0027] (2), Perform primary aging treatment on the quenched aluminum alloy bar in an aging furnace, control the aging treatment temperature to be 160 °C, and the treatment time to be 3 h;

[0028] (3), Perform high-speed impact on the aluminum alloy bar after aging treatment through a Hopkinson bar device, control the strain rate of the high-speed impact to be 3000 s -1 , and the pre-deformation amount to be 5%;

[0029] (4), Perform creep age forming on the aluminum alloy bar after high-speed impact pre-deformation, control the creep age temperature to be 160 °C, the time to be 16 h, and the creep stress to be 200 Mpa, and finally obtain an aluminum alloy finished product.

[0030] Embodiment 2: A method for improving the creep age forming performance of aluminum alloy, including the following specific steps:

[0031] (1), Put the 2195 aluminum alloy into an air-circulating resistance furnace, perform solution treatment at a temperature of 510 °C for 30 min, take it out and perform water quenching to obtain an aluminum alloy bar;

[0032] (2) Subject the quenched aluminum alloy bar to primary aging treatment in an aging furnace, controlling the aging treatment temperature at 120°C and the treatment time at 6 h;

[0033] (3) Conduct high-speed impact on the aluminum alloy bar after aging treatment through a Hopkinson bar device, controlling the strain rate of high-speed impact at 5000 s -1 , and the pre-deformation amount at 12%;

[0034] (4) Subject the aluminum alloy bar after high-speed impact pre-deformation to creep aging forming, controlling the creep aging temperature at 250°C, the time at 10 h, and the creep stress at 200 Mpa, and finally obtain the aluminum alloy finished product.

[0035] Example 3: A method for improving the creep aging forming performance of aluminum alloy, including the following specific steps:

[0036] (1) Place 2195 aluminum alloy in an air-circulating resistance furnace, conduct solution treatment at a temperature of 510°C for 30 min, take it out and quench it in water to obtain an aluminum alloy bar;

[0037] (2) Subject the quenched aluminum alloy bar to primary aging treatment in an aging furnace, controlling the aging treatment temperature at 100°C and the treatment time at 10 h;

[0038] (3) Conduct high-speed impact on the aluminum alloy bar after aging treatment through a Hopkinson bar device, controlling the strain rate of high-speed impact at 1000 s -1 , and the pre-deformation amount at 5%;

[0039] (4) Subject the aluminum alloy bar after high-speed impact pre-deformation to creep aging forming, controlling the creep aging temperature at 100°C, the time at 20 h, and the creep stress at 150 Mpa, and finally obtain the aluminum alloy finished product.

[0040] Example 4: A method for improving the creep aging forming performance of aluminum alloy, including the following specific steps:

[0041] (1) Place 7075 aluminum alloy in an air-circulating resistance furnace, conduct solution treatment at a temperature of 480°C for 30 min, take it out and quench it in water to obtain an aluminum alloy bar;

[0042] (2) Subject the quenched aluminum alloy bar to secondary aging treatment in an aging furnace, controlling the temperature of the first-stage aging treatment at 115°C and the treatment time at 6 h; the temperature of the second-stage aging treatment at 140°C and the treatment time at 1.5 h;

[0043] (3) Conduct high-speed impact on the aluminum alloy bar after aging treatment through a Hopkinson bar device, controlling the strain rate of high-speed impact at 1500 s -1, the pre-deformation amount is 7%;

[0044] (4) Subject the pre-deformed aluminum alloy bar after high-speed impact to creep age forming, control the creep age temperature at 120 °C, the time at 16 h, and the creep stress at 200 Mpa, and finally obtain the aluminum alloy finished product.

[0045] Comparative Example 1:

[0046] Place the 2195 aluminum alloy in an air-circulating resistance furnace, solution treat it at a temperature of 510 °C for 30 min, take it out and quench it in water to obtain an aluminum alloy bar; subject the quenched aluminum alloy bar to primary aging treatment in an aging furnace, control the aging treatment temperature at 160 °C, and the treatment time at 3 h; then, on a room-temperature tensile testing machine, stretch the aluminum alloy bar at a rate of 2 mm / min to a pre-deformation amount of 5%; finally, subject the aluminum alloy bar to creep age forming, control the creep age temperature at 160 °C, the time at 16 h, and the creep stress at 200 Mpa to obtain the aluminum alloy finished product.

[0047] Comparative Example 2:

[0048] Place the 2195 aluminum alloy in an air-circulating resistance furnace, solution treat it at a temperature of 510 °C for 30 min, take it out and quench it in water to obtain an aluminum alloy bar; subject the quenched aluminum alloy bar to primary aging treatment in an aging furnace, control the aging treatment temperature at 160 °C, and the treatment time at 3 h; then subject the aluminum alloy bar to creep age forming, control the creep age temperature at 160 °C, the time at 16 h, and the creep stress at 200 Mpa to obtain the aluminum alloy finished product.

[0049] Comparative Example 3:

[0050] Place the 7075 aluminum alloy in an air-circulating resistance furnace, solution treat it at a temperature of 510 °C for 30 min, take it out and quench it in water to obtain an aluminum alloy bar; subject the quenched aluminum alloy bar to secondary aging treatment in an aging furnace, control the temperature of the first-stage aging treatment at 115 °C, and the treatment time at 6 h; the temperature of the second-stage aging treatment at 140 °C, and the treatment time at 1.5 h; then, on a room-temperature tensile testing machine, stretch the aluminum alloy bar at a rate of 2 mm / min to a pre-deformation amount of 7%; finally, subject the aluminum alloy bar to creep age forming, control the creep age temperature at 120 °C, the time at 16 h, and the creep stress at 200 Mpa to obtain the aluminum alloy finished product.

[0051] Comparative Example 4:

[0052] Put the 7075 aluminum alloy into an air-circulation resistance furnace and perform solution treatment at a temperature of 510 °C for 30 min. After taking it out and quenching it in water, an aluminum alloy bar is obtained; the quenched aluminum alloy bar is subjected to two-stage aging treatment in an aging furnace. Control the temperature of the first-stage aging treatment to be 115 °C and the treatment time to be 6 h; the temperature of the second-stage aging treatment is 140 °C and the treatment time is 1.5 h; then the aluminum alloy bar is subjected to creep aging forming, control the creep aging temperature to be 120 °C, the time to be 16 h, and the creep stress to be 200 Mpa to obtain the finished aluminum alloy product.

[0053] The 2195 aluminum alloy and 7075 aluminum alloy used in the above examples and comparative examples are both obtained by hot rolling; and the creep aging forming of the aluminum alloy bar is carried out on a high-temperature creep rupture strength testing machine, and the temperature control accuracy of the testing machine is ±2 °C, and the load accuracy is ±3 N.

[0054] After the final aluminum alloy bar products formed in all the above examples and comparative examples are cooled at room temperature, a tensile test is carried out. The standard adopted for the tensile test is: GB / T228 2002, and the results are as Figure 2-5 shown. It can be seen from the figure that: under the same temperature and stress conditions, the aluminum-lithium alloy and 7-series aluminum alloy treated by the method of the present invention have a creep variable increase of 20-130% compared with the creep variable after the conventional slow-rate pre-deformation treatment in the traditional T3 and T4 states, the yield strength can be increased by 15-35%, and the tensile strength is increased by 15-35%. The above data prove that the creep aging forming process proposed by the present invention can greatly improve the creep variable and mechanical properties of aluminum alloy components, and the components can obtain a large creep variable and excellent mechanical properties under creep aging at a lower temperature and stress.

[0055] The protection scope of the present invention includes but is not limited to the above embodiments. The protection scope is subject to the claims. Any replacement, deformation, and improvement that are easily conceivable by those skilled in the art to this technology fall within the protection scope of the present invention.

Claims

1. A method for improving the creep age forming performance of aluminum alloy, characterized in that It includes the following specific steps: (1) Solutionize and water quench the billets of aluminum-lithium alloy, 2xxx series aluminum alloy or 7xxx series aluminum alloy to obtain semi-finished aluminum alloy products; (2) Perform aging treatment on the quenched semi-finished aluminum alloy products; (3) Subject the aged aluminum alloy semi-finished product to high-speed impact pre-deformation, and control the strain rate of the high-speed impact to be 100 - 6000 s -1 , and the deformation amount is 0.1 - 15%; (4) Perform creep aging forming on the semi-finished aluminum alloy products after high-speed impact pre-deformation, control the creep aging temperature at 60 - 300 °C, the time at 2 - 20 h, and the creep stress at 50 - 650 Mpa to obtain finished aluminum alloy products.

2. The method for improving the creep age forming performance of aluminum alloy according to claim 1, characterized in that: In step (2) described above, the aging treatment temperature is 60 - 250 °C, and the aging time is 0.5 - 20 h.

3. The method for improving the creep age forming performance of aluminum alloy according to claim 1, characterized in that: In step (2) described above, the aging treatment is 1 - 4 level aging heat treatment.

4. A method for improving the creep age forming performance of aluminum alloy as claimed in claim 1, characterized in that: The aluminum alloy billets are obtained by hot rolling.

Images