Aluminum alloy conductor material heat treatment process selection method

Abstract

The invention provides an aluminum alloy conductor material heat treatment process selection method, which utilizes differential scanning calorimetry (DSC) to obtain the phase transition temperature of an aluminum alloy so as to confirm the solid solution and aging temperature in the aluminum alloy heat treatment process, and selects the solid solution time through the conductivity performance of the aluminum alloy after solid solution. The proper aging time is selected according to the tensile strength, the conductivity and other properties of the aluminum alloy, and finally the proper heat treatment process of the aluminum alloy material is obtained. The heat treatment process selection method combines theory and reality, and is higher in feasibility; different from the previous method for confirming the material heat treatment process through conjecture and hypothesis and a large number of test verification, the method can obtain the clear aluminum alloy heat treatment temperature through the aluminum alloy phase transition temperature, then the heat treatment time is clear through test verification and performance requirements, a large number of test verification time is shortened, and the research and development efficiency is improved; and as the tests of the aluminum alloy heat treatment process for verification are reduced, the labor cost and financial resource consumption are saved.

Description

Technical Field

[0001] The invention relates to the technical field of metal heat treatment, and in particular to a method for selecting a heat treatment process for an aluminum alloy conductor material. Background Art

[0002] Aluminum alloy is not only light in weight and high in specific strength, but also has a series of characteristics such as good plasticity, corrosion resistance, easy processing, excellent electrical and thermal conductivity, unique metallic luster, surface treatment, and low price. It has become one of the most widely used and economical metal materials in the world. In today's frequent power grid renewal, aluminum alloy is also regarded as the first choice for high-strength and high-conductivity materials. With the development of science and the advancement of technology, the requirements for alloy performance are becoming more and more stringent, and heat treatment technology is the key means to improve the strength and conductivity of aluminum alloy. The heat treatment process of aluminum alloy mainly includes solution treatment and aging treatment. Solution treatment refers to the process of alloying elements and second phases dissolving into the matrix, while aging treatment is the process of precipitating fine dispersed precipitation phases after solution. After heat treatment, aluminum alloy can improve the comprehensive performance of the alloy and meet the corresponding engineering technical requirements.

[0003] At present, there are many kinds of heat treatment processes for aluminum alloys. The type, composition, size and performance requirements of aluminum alloys affect the selection of heat treatment processes for aluminum alloys. The main parameters of heat treatment processes are solution temperature, solution aging, cooling method, aging temperature and aging time. These process parameters determine the heat treatment process of aluminum alloys. The heat treatment processes of different aluminum alloys are different. During the solution process, the dissolution temperature and maximum solubility of different alloying elements and second phases dissolved into the aluminum matrix are different, resulting in great differences in the selection of solution temperature and solution time. In the aging process, the aging temperature and aging time affect the state of the precipitation phase of the aluminum alloy, thereby affecting the final performance of the aluminum alloy. The heat treatment process of aluminum alloys is generally determined by the accumulated research of predecessors and a large number of test results. The process is complicated and full of uncertainty, requiring a lot of manpower, capital and time costs to verify, affecting the update and iteration of aluminum alloy products. Summary of the invention

[0004] In view of the above-mentioned defects, an object of the present invention is to provide a method for selecting a heat treatment process for aluminum alloy conductor materials, which method can select a suitable heat treatment process for aluminum alloys through thermal analysis and performance verification.

[0005] The present invention provides a method for selecting a heat treatment process for an aluminum alloy conductor material, comprising the following steps:

[0006] S1. Selecting a first sample for which a heat treatment process needs to be determined, wherein the surface of the first sample has no cracks or defects, and selecting a first sample from the first sample;

[0007] S2. performing a differential scanning calorimetry test on the first sample to obtain a first test result;

[0008] S3, analyzing the DSC curve in the first test result, and determining the solid solution temperature T in the heat treatment process according to the temperature range of the endothermic peak in the DSC curve. 1 ;

[0009] S4, subjecting the first sample to solid solution at temperature T 1 The heat treatment with different solution time was carried out, and the conductivity of the samples after heat treatment was tested. The solution time t in the heat treatment process was determined according to the samples whose conductivity no longer decreased with the increase of solution time. 1 ;

[0010] S5, subjecting the first sample to solid solution at temperature T 1 , solution time t 1 Solution treatment is performed to obtain a second sample, and a second sample is selected from the second sample;

[0011] S6. Performing a differential scanning calorimetry test on the second sample to obtain a second test result;

[0012] S7, analyzing the DSC curve in the second test result, and determining the aging temperature T in the heat treatment process according to the temperature range of the exothermic peak in the DSC curve. 2 ;

[0013] S8, heat treatment the second sample at different aging times at aging temperature T2, test the performance of the sample after heat treatment, and select a suitable aging time t according to the performance requirements of the sample 2 ;

[0014] S9, according to the above solution temperature T 1 , solution time t 1 , aging temperature T 2 and time t 2 , determine the final heat treatment process of the first sample.

[0015] Preferably, in the step S1, the first sample should be prevented from being heated and deformed during sampling.

[0016] Preferably, in step S2, nitrogen protection is used throughout the differential scanning calorimetry test, the gas flow rate is 50 ml / min, the temperature is increased from room temperature to 600° C., and the heating rate is 10° C. / min.

[0017] Preferably, in step S5, the second sample should be prevented from being heated and deformed during sampling.

[0018] Preferably, in step S6, nitrogen protection is used throughout the differential scanning calorimetry test, the gas flow rate is 50 ml / min, the temperature is increased from room temperature to 350° C., and the heating rate is 10° C. / min.

[0019] The present invention uses differential scanning calorimetry (DSC) to obtain the phase transition temperature of the aluminum alloy, thereby confirming the solid solution and aging temperatures in the aluminum alloy heat treatment process, selecting the solid solution time according to the electrical conductivity of the aluminum alloy after solid solution, and selecting the appropriate aging time according to the tensile strength, electrical conductivity and other properties of the aluminum alloy, and finally obtaining a suitable heat treatment process for the aluminum alloy material. The heat treatment process selection method combines theory with practice and has higher feasibility; different from the previous method of confirming the material heat treatment process through conjectures and assumptions and a large number of experimental verifications, this method can obtain a clear aluminum alloy heat treatment temperature through the aluminum alloy phase transition temperature, and then clarify the heat treatment time through experimental verification and performance requirements, which reduces a lot of experimental verification time and improves research and development efficiency; and because the number of experiments for verifying the aluminum alloy heat treatment process is reduced, human costs and financial consumption are saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the DSC curve of the first sample;

[0021] Figure 2 is the DSC curve of the second sample. DETAILED DESCRIPTION

[0022] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present invention, but not to limit the present invention. The terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0023] The present invention provides a method for selecting a heat treatment process for an aluminum alloy conductor material, the method comprising the following steps:

[0024] S1. Select a first sample for which a heat treatment process needs to be determined. The surface of the first sample has no cracks or defects. Select a 5-10 mg block or sheet first sample from the first sample.

[0025] S2. performing a differential scanning calorimetry test on the first sample to obtain a first test result;

[0026] S3, analyzing the DSC curve in the first test result, and determining the solid solution temperature T in the heat treatment process according to the temperature range of the endothermic peak in the DSC curve. 1 ;

[0027] S4. Solvent temperature T 1The heat treatment with different solution time was carried out, and the conductivity of the samples after heat treatment was tested. The solution time t in the heat treatment process was determined according to the samples whose conductivity no longer decreased with the increase of solution time. 1 ;

[0028] S5. Solvent temperature T 1 , solution time t 1 Solution treatment is performed to obtain a second sample, and 5-10 mg of a block or sheet second sample is selected from the second sample;

[0029] S6. Perform a differential scanning calorimetry test on the second sample to obtain a second test result;

[0030] S7, analyzing the DSC curve in the second test result, and determining the aging temperature T in the heat treatment process according to the temperature range of the exothermic peak in the DSC curve. 2 ;

[0031] S8. Heat treat the second sample at different aging times at aging temperature T2, test the performance of the sample after heat treatment, and select a suitable aging time t according to the performance requirements of the sample. 2 ;

[0032] S9, according to the above solution temperature T 1 , solution time t 1 , aging temperature T 2 and time t 2 , determine the final heat treatment process of the first sample.

[0033] The present invention applies the DSC thermal analysis method for studying material phase change to the selection of heat treatment process for aluminum alloy conductor materials, and determines the appropriate heat treatment temperature of the aluminum alloy by observing the DSC curve of heat change during the second phase phase change in the aluminum alloy; determines the heat treatment temperature through DSC test, and then determines the heat treatment time according to the performance change after heat treatment and the final alloy performance requirements, thereby reducing the cumbersome trial production and verification tests of the heat treatment process in the past, saving time, and improving research and development efficiency. The selection method of the present invention can reduce the tests for verifying the heat treatment process of the aluminum alloy, reduce the cumbersome and repeated test verification links, and greatly save manpower costs and financial consumption.

[0034] Example

[0035] S1. Select the first sample A for which the heat treatment process needs to be determined. The first sample A is an Al-Mg-Si aluminum alloy, and its surface should be free of cracks and defects. Select 5-10 mg of the first sample a in block or sheet form from the first sample A. When sampling, avoid heating and deformation of the first sample a.

[0036] S2. Perform a differential scanning calorimetry (DSC) test on the first sample a. During the test, nitrogen protection is used throughout the test, and the gas flow rate is 50 ml / min. The temperature is increased from room temperature to 600°C, and the heating rate is 10°C / min. Finally, the first test result is obtained, such as Figure 1 shown.

[0037] S3, analyze the DSC curve in the first test result, such as Figure 1 As shown in the figure, the horizontal axis is temperature and the vertical axis is heat flow rate. During the solution treatment, the second phase in the aluminum alloy sample dissolves into the matrix and produces an endothermic phenomenon, which is manifested as a downward endothermic peak in the DSC curve. Figure 1 It can be seen that the first sample a has a downward endothermic peak in the range of 480℃-540℃, and the peak temperature is 520℃, so the solution temperature T in the heat treatment process can be determined. 1 It is 520℃.

[0038] S4. The four first samples A were subjected to heat treatment at 520°C for four different solution times (30min, 45min, 60min and 75min), and the electrical conductivity of the samples after heat treatment was tested, as shown in Table 1. As shown in Table 1, the electrical conductivity of the first sample A3 and the first sample A4 no longer decreases with the increase of solution time. It can be seen that the aluminum alloy of the first sample A3 has a better solution strengthening effect and the element solution is more complete. Therefore, the solution time t in the heat treatment process is determined. 1 For 60 minutes.

[0039] Table 1 Properties of the first sample A after solution treatment

[0040]

[0041] S5. Select the first sample A for solution temperature T 1 =520℃, solution time t 1 = 60min of solution treatment to obtain a second sample B, and select 5-10mg of a block or sheet second sample b from the second sample B. When sampling, the second sample b should be prevented from being heated and deformed.

[0042] S6. Perform a differential scanning calorimetry (DSC) test on the second sample b. Nitrogen protection is used throughout the test, and the gas flow rate is 50 ml / min; the temperature is increased from room temperature to 350°C, and the heating rate is 10°C / min. Finally, the second test result is obtained, such as Figure 2 shown.

[0043] S7, analyzing the DSC curve in the second test result, such as Figure 2As shown in the figure, the horizontal axis is temperature and the vertical axis is heat flow rate. During the aging treatment, the precipitation of the second phase in the aluminum matrix of the aluminum alloy will produce heat release, which is manifested as an upward exothermic peak in the DSC curve. In addition, due to the changes in the precipitated second phase, multiple exothermic peaks will appear. Figure 2 It can be seen that the second sample b has multiple upward exothermic peaks, among which peak 1 represents the precipitation of Mg and Si clusters in the aluminum alloy, with a temperature range of 78°C-80°C; peak 2 represents the precipitation of GP zone, with a temperature range of 107°C-109°C; peak 3 represents the precipitation of β” phase, with a temperature range of 149°C-151°C; peak 4 represents the precipitation of β' phase, with a temperature range of 202°C-204°C; peak 5 represents the precipitation of β phase, with a temperature range of 230°C-270°C. Among them, β” phase is the main strengthening phase, and the precipitation temperature is between 150°C-200°C, so the aging temperature T in the heat treatment process can be selected. 2 is 175°C.

[0044] S8. Heat treatment of the four second samples B at 175°C for four different aging times (2h, 4h, 6h and 8h) was performed respectively, and the performance of the samples after heat treatment was tested. As shown in Table 2, the appropriate aging time t can be selected according to the performance requirements of the samples. 2 If a high-strength aluminum alloy is required, the aging time of 4h corresponding to the second sample B2 can be selected; if a high-conductivity aluminum alloy is required, the aging time of 8h corresponding to the second sample B4 can be selected.

[0045] Table 2 Properties of the second sample B after aging treatment

[0046]

[0047] S9. In summary, the heat treatment process of high-strength aluminum alloy is 520℃*60min solution treatment and 175℃*4h aging treatment; the heat treatment process of high-conductivity aluminum alloy is 520℃*60min solution treatment and 175℃*8h aging treatment.

[0048] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for selecting a heat treatment process for an aluminum alloy conductor material, characterized in that: The following steps are involved: S1. Selecting a first sample for which a heat treatment process needs to be determined, wherein the surface of the first sample has no cracks or defects, and selecting a first sample from the first sample; S2. performing a differential scanning calorimetry test on the first sample to obtain a first test result; S3, analyzing the DSC curve in the first test result, and determining the solid solution temperature T1 in the heat treatment process according to the temperature range of the endothermic peak in the DSC curve; S4, performing heat treatment on the first sample at a solution temperature T1 with different solution times, detecting the conductivity of the sample after the heat treatment, and determining the solution time t1 in the heat treatment process according to the sample whose conductivity no longer decreases with increasing solution time; S5, performing a solution treatment at a solution temperature T1 and a solution time t1 on the first sample to obtain a second sample, and selecting a second sample from the second sample; S6. Performing a differential scanning calorimetry test on the second sample to obtain a second test result; S7, analyzing the DSC curve in the second test result, and determining the aging temperature T2 in the heat treatment process according to the temperature range of the exothermic peak in the DSC curve; S8, performing heat treatment on the second sample at different aging times at an aging temperature T2, detecting the performance of the sample after the heat treatment, and selecting a suitable aging time t2 according to the performance requirements of the sample; S9. Determine the final heat treatment process of the first sample according to the above-mentioned solution temperature T1, solution time t1, aging temperature T2 and aging time t2.

2. The method for selecting a heat treatment process for an aluminum alloy conductor material according to claim 1, characterized in that: In the step S1, the first sample should be prevented from being heated and deformed during sampling.

3. The method for selecting a heat treatment process for an aluminum alloy conductor material according to claim 1, characterized in that: In the step S2, nitrogen protection is used throughout the differential scanning calorimetry test, the gas flow rate is 50 ml / min, the temperature is increased from room temperature to 600° C., and the heating rate is 10° C. / min.

4. The method for selecting a heat treatment process for an aluminum alloy conductor material according to claim 1, characterized in that: In the step S5, the second sample should be prevented from being heated and deformed during sampling.

5. The method for selecting a heat treatment process for an aluminum alloy conductor material according to claim 1, characterized in that: In the step S6, nitrogen protection is used throughout the differential scanning calorimetry test, the gas flow rate is 50 ml / min, the temperature is increased from room temperature to 350° C., and the heating rate is 10° C. / min.

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