A method for preparing 2050 aluminum-lithium alloy plate

Abstract

The invention belongs to the field of aluminum alloy materials and discloses a preparation method of a 2050 aluminum-lithium alloy plate. The plate is obtained by ingot casting-milling-heating-hot rolling-solid solution-stretching-cold rolling-re-stretching-aging treatment. The internal grains are stabilized by controlling the steps of hot rolling and solid solution, so that the grains of the plate can be fully stabilized, the toughness and rigidity of the product are guaranteed, and the plate is prevented from cracking. The finally obtained plate has good tensile strength, yield strength and elongation.

Description

Technical Field

[0001] The invention belongs to the field of metal materials and thermal processing thereof, and specifically is a method for preparing a 2050 aluminum-lithium alloy plate. Background Art

[0002] At present, Russia and China are the main countries that have conducted research and achieved certain results in high heat-resistant aluminum (lithium) alloys (using temperatures exceeding 250°C). Among them, Russia's Al-Cr-Zr series aluminum alloy strips prepared by rapid solidification have good high-temperature performance. In addition, Russia's Al-3.3%Cu-2.5%Mn-0.5%Zr strips prepared by electromagnetic casting also show good high-temperature stability. Xi'an Jiaotong University in my country recently added 0.3%Sc element to the cast Al-4.5%Cu-0.3%Mg-0.4%Ag alloy to further improve the stability of the precipitated phase. The alloy maintained a certain high-temperature stability at 400°C. The maximum operating temperature of traditional Al-Cu-Mn and Al-Cu-Mg-Fe-Ni heat-resistant aluminum alloys does not exceed 250°C, the temperature at which they can be used for a long time does not exceed 200°C, and the weldability of the alloy is poor; while the existing engine skins and bulkheads, the skins and support frames of high-speed unmanned weapons need to maintain sufficient strength within the temperature range of 250°C to 300°C. At the same time, in order to reduce manufacturing costs and improve reliability, the material needs to have good welding properties, and the existing traditional heat-resistant aluminum alloys cannot meet the usage requirements.

[0003] Compared with traditional heat-resistant aluminum alloys, the new heat-resistant aluminum-lithium alloy can obtain macroscopic and microscopic structures with good high-temperature stability through the design of alloy components and the regulation of preparation process. The strength at 250-300°C reaches more than 300MPa, which meets the use temperature requirements. In addition, compared with traditional heat-resistant aluminum alloys, the density of the new heat-resistant aluminum-lithium alloy is reduced by 4%, the stiffness is increased by 10%, and the strength of the fusion welding joint can reach about 75%. Therefore, it is suitable for use in high-temperature parts in the aviation and aerospace fields, which can achieve a good weight reduction effect.

[0004] 2050 aluminum-lithium alloy is a third-generation aluminum-lithium alloy. During the process of preparing the plate, cracking of the plate often occurs, which affects the performance of the product. Therefore, it is of broad significance to improve the process of preparing the plate and improve the performance of the product for its application. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for preparing a 2050 aluminum-lithium alloy plate, and the specific technical scheme is as follows:

[0006] A method for preparing a 2050 aluminum-lithium alloy plate comprises the following steps:

[0007] Step 1: Casting 2050 aluminum-lithium alloy ingot;

[0008] Step 2, milling the ingot from step 1;

[0009] Step 3: heating the ingot in step 2 to 430-450°C and keeping the temperature for 4-8 hours;

[0010] Step 4: hot rolling the product in step 3, with the first hot rolling temperature being 440-480°C and the final rolling temperature being 320-400°C;

[0011] Step 5: The product in step 4 is subjected to solution treatment. The solution treatment steps are: firstly, the first stage of heating is performed at a temperature of 490-500°C and a holding time of 40-60min, and then the second stage of heating is performed at a heating temperature of 500-510°C and a holding time of 20-40min; then, quenching treatment is performed, the quenching water temperature is 25-35°C, and the quenching transfer time does not exceed 18 seconds, and finally, pre-stretching is performed, and the pre-stretching amount is 3.8-4.2%;

[0012] Step 6: cold rolling the plate obtained in step 5;

[0013] Step 7: Pre-stretch and age the plate obtained in step 6 to obtain a 2050 aluminum-lithium alloy plate.

[0014] As a further improvement, it is characterized in that: the specific steps of step 1 are: subjecting the 2050 aluminum-lithium alloy to a secondary homogenization treatment at 470°C / 8h+505°C / 24h, and air cooling to room temperature after the homogenization treatment. The secondary homogenization treatment eliminates the original internal stress, so that the performance of the subsequent product is uniform.

[0015] As a further improvement, it is characterized in that: the milling step of step 2 is: the large surface is milled clean, the small surface is not milled, chamfering is performed, and cracks on the large and small surfaces are milled clean.

[0016] As a further improvement, it is characterized in that: in step 4, the rolling force of the first stage of hot rolling is 2200-2600t.

[0017] As a further improvement, it is characterized in that: in the step 3, when the ingot is heated, the end face of the ingot is punched, the punching depth is greater than 40mm, and when the internal temperature is detected to be 430-450℃, insulation is started.

[0018] The beneficial effects of the present invention are as follows: the 2050 aluminum-lithium alloy plate obtained by the method of the present invention can make the grains of the plate fully stable through two-stage hot rolling and solution treatment, ensure the toughness and rigidity of the product, prevent the plate from cracking, and the finally obtained plate has good tensile strength, yield strength and elongation. DETAILED DESCRIPTION

[0019] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not limit the scope of protection.

[0020] A method for preparing a 2050 aluminum-lithium alloy plate comprises the following steps:

[0021] Step 1: subjecting the 2050 aluminum-lithium alloy to a secondary homogenization treatment at 470°C / 8h+505°C / 24h, air-cooling to room temperature after the homogenization treatment, and forming an ingot;

[0022] Step 2, milling the ingot in step 1, milling the large surface cleanly, not milling the small surface, performing chamfering, and milling cleanly the large and small surfaces with cracks;

[0023] Step 3: Punch a hole on the end face of the ingot with a depth greater than 40 mm, heat the ingot in step 2, and when the internal temperature of the ingot is detected to be 440°C, start heat preservation for 5 hours;

[0024] Step 4: hot rolling the product in step 3, the first hot rolling temperature is 450°C, see Table 1 for details, and the final rolling temperature is 320°C;

[0025] Table 1

[0026]

[0027] Step 5: The product in step 4 is subjected to solution treatment. The solution treatment steps are: firstly, the first stage of heating is performed at a temperature of 495°C and a holding time of 40 minutes, and then the second stage of heating is performed at a heating temperature of 505°C and a holding time of 30 minutes; then, quenching treatment is performed, the quenching water temperature is 30°C, and the quenching transfer time does not exceed 18 seconds, and finally, pre-stretching is performed, and the pre-stretching amount is 4%;

[0028] Step 6: cold rolling the plate obtained in step 5;

[0029] Step 7: Pre-stretch and age the plate obtained in step 6 to obtain a 2050 aluminum-lithium alloy plate.

[0030] The prepared 2050 aluminum-lithium alloy sheet was subjected to a room temperature tensile property test, and the results showed: Rm: 590 MPa, Rp0.2: 560 MPa, elongation: 9.5%, and good performance.

Claims

1. A method for preparing a 2050 aluminum-lithium alloy plate, comprising the following steps: Step 1: Casting 2050 aluminum-lithium alloy ingot; Step 2, milling the ingot from step 1; Step 3: heating the ingot in step 2 to 430-450°C and keeping the temperature for 4-8 hours; Step 4: hot rolling the product in step 3, with the first hot rolling temperature being 440-480°C and the final rolling temperature being 320-400°C; Step 5: The product in step 4 is subjected to solution treatment. The solution treatment steps are: firstly, the first stage of heating is performed at a temperature of 490-500°C and a holding time of 40-60min, and then the second stage of heating is performed at a heating temperature of 500-510°C and a holding time of 20-40min; then, quenching treatment is performed, the quenching water temperature is 25-35°C, and the quenching transfer time does not exceed 18 seconds, and finally, pre-stretching is performed, and the pre-stretching amount is 3.8-4.2%; Step 6: cold rolling the plate obtained in step 5; Step 7: Pre-stretch and age the plate obtained in step 6 to obtain a 2050 aluminum-lithium alloy plate.

2. The method for preparing a 2050 aluminum-lithium alloy sheet according to claim 1, characterized in that: The specific steps of step 1 are: subjecting the 2050 aluminum-lithium alloy to a secondary homogenization treatment at 470° C. / 8 h+505° C. / 24 h, and air-cooling to room temperature after the homogenization treatment.

3. The method for preparing a 2050 aluminum-lithium alloy sheet according to claim 1, characterized in that: The milling steps of step 2 are as follows: the large surface is milled cleanly, the small surface is not milled, and chamfering is performed, and cracks on the large and small surfaces are milled cleanly.

4. The method for preparing a 2050 aluminum-lithium alloy sheet according to claim 1, characterized in that: In step 4, the rolling force of the first stage of hot rolling is 2200-2600t.

5. The method for preparing a 2050 aluminum-lithium alloy sheet according to claim 1, characterized in that: In the step 3, when the ingot is heated, the end face of the ingot is punched with a hole having a depth greater than 40 mm, and when the internal temperature is detected to be 430-450° C., insulation is started.

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