Heat treatment process optimization method for heat-treatable strengthened aluminum alloy based on phase calculation

Abstract

The invention provides a heat treatment process optimization method for a heat-treatable strengthened aluminum alloy based on phase calculation, and belongs to the technical field of heat treatment process optimization. The method is designed on the basis of Jmatpro software, according to components of the to-be-optimized heat-treatment-strengthened aluminum alloy, all phases forming the aluminum alloy are set as components, and a TTT curve and a CCT curve are calculated; according to the solid solution temperature range obtained through calculation, the solid solution temperature is set on Jmatpro software, and the solid solution temperature is set according to an aluminum alloy TTT curve and does not exceed the traditional overburning solid solution temperature of the corresponding type of aluminum alloy products; then, according to the components of the heat-treatable reinforced aluminum alloy, the preset aging temperature is set, a phase-time curve is drawn, the optimal aging temperature is obtained, and the aging time is deduced. According to the heat treatment optimization method provided by the invention, the trial and error cost is reduced, and the test efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of heat treatment of aluminum alloys, and in particular to a heat treatment process optimization method for heat-treatable and strengthened aluminum alloys based on phase calculation. Background Art

[0002] Aluminum alloy has low density but high strength, close to or exceeding high-quality steel, good plasticity, can be processed into various profiles, has excellent electrical conductivity, thermal conductivity and corrosion resistance, and is widely used in industry, second only to steel in usage. Heat-treatable and strengthened aluminum alloys are widely used in the automotive, aerospace, rail transportation and other fields, and in recent years, the comprehensive performance requirements for aluminum alloys have become more stringent.

[0003] The improvement of the comprehensive performance of heat-treatable aluminum alloys is mainly achieved through the following two methods: one is to optimize the types and ratios of alloying elements; the other is to optimize the heat treatment process. The heat treatment process affects the comprehensive performance of the alloy by affecting the precipitation and balance of each phase of the aluminum alloy. For example, the improvement of the performance of Al-Zn-Mg-Cu aluminum alloys is mainly to control the balance of each precipitation phase during the heat treatment process, including S phase, T phase, S' phase, GP zone, η' phase and MgZn2 phase. The residual S phase and T phase in the solid solution quenching process are beneficial to improve plasticity and toughness, increase damage tolerance performance, but will cause strength reduction; S' phase, GP zone, η' phase and MgZn2 phase will be produced during the aging process, and their effects on the performance of aluminum alloys are very complex. GP zone and η' phase can improve the strength of the material, but reduce some toughness; MgZn2 phase can improve toughness and corrosion resistance, but will reduce strength. Therefore, the precipitation and mutual coordination of each phase can be controlled by optimizing the heat treatment process, thereby balancing the comprehensive performance of the alloy.

[0004] At present, the research on traditional aluminum alloy materials and the development of new materials mainly adopt the "trial and error method" to regulate the balance of various phases in aluminum alloys, that is, to explore the appropriate heat treatment process for a certain material through a large number of experiments, resulting in the application speed of new materials lagging far behind the development of new products. Based on this, a heat treatment process optimization method for heat-treatable strengthening aluminum alloy based on phase calculation is proposed to improve the efficiency of heat treatment optimization and reduce costs. Summary of the invention

[0005] To solve the above technical problems, the present invention provides a heat treatment process optimization method for heat-treatable and strengthened aluminum alloys based on phase calculation. The isothermal transformation curve (TTT curve), continuous cooling transformation curve (CCT curve) and precipitation relationship curves of each phase at different solid solution and aging temperatures of the heat-treatable and strengthened aluminum alloy are calculated by a numerical simulation method, providing a theoretical basis for optimizing the heat treatment process of the aluminum alloy and adjusting the composition of the precipitated phase.

[0006] The technical solution of the present invention is as follows:

[0007] The present invention provides a method for optimizing the heat treatment process of a heat-treatable and strengthened aluminum alloy based on phase calculation, comprising the steps of:

[0008] (1) Determine the element composition and content of the heat-treatable and strengthened aluminum alloy to be optimized;

[0009] (2) Input the composition elements and contents of the heat-treatable aluminum alloy to be optimized in step (1) into the Jmatpro software, select the components in the aluminum alloy, set the initial calculation temperature, and calculate its TTT curve and CCT curve;

[0010] (3) After the calculation is completed, the TTT curve and CCT curve are output. The solid solution temperature range and solid solution transfer time are obtained through the TTT curve, and the quenching cooling rate is calculated through the CCT curve;

[0011] (4) according to the solution temperature range obtained in step (3), the solution temperature is set in the Jmatpro software, and the preset aging temperature is set, and then the components in the aluminum alloy are selected, and the change curves of each phase with time at different aging temperatures are calculated, and the aging temperature and aging time suitable for the aluminum alloy are determined in combination with the performance requirements of the heat-treatable aluminum alloy to be optimized;

[0012] (5) Based on the calculation results of steps (3) and (4), the optimal heat treatment process including solution temperature, solution transfer time, quenching rate, aging temperature and aging time suitable for the heat-treatable aluminum alloy to be optimized is obtained.

[0013] Furthermore, the heat-treatable and strengthened aluminum alloy in step (1) is one of Al-Cu-Mg alloy and Al-Zn-Mg-Cu alloy.

[0014] Furthermore, when the heat-treatable strengthening aluminum alloy in step (1) is an Al-Cu-Mg alloy, the components in the Al-Cu-Mg alloy in steps (2) and (3) are set to include S phase, Al2Cu phase, S' phase, θ' phase, and GP zone;

[0015] When the heat-treatable and strengthened aluminum alloy in step (1) is an Al-Zn-Mg-Cu alloy, the components in the Al-Zn-Mg-Cu alloy in steps (2) and (3) are set to include S phase, T phase, S' phase, GP zone, η' phase and MgZn2 phase.

[0016] Furthermore, the initial calculation temperature set in step (2) is 500-550°C.

[0017] Furthermore, the quenching cooling rate in step (3) is obtained according to the critical cooling rate of the component, and the calculation process is as follows:

[0018] Set two coordinates, one of which is the point on the ordinate, representing the solution temperature, which is (0, y1) on the CCT diagram, and the other is the point on the far left of the CCT diagram (x2, y2). The critical cooling rate V of the alloy k The calculation formula is:

[0019] V k =|(y2-y1) / (x2-0)|.

[0020] Furthermore, the lower limit of the preset solution temperature in step (4) is the highest point in the TTT curve, and the upper limit is the overburning temperature of the heat-treatable strengthened aluminum alloy.

[0021] Furthermore, the preset aging temperature in step (4) is room temperature to 300°C.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] (1) The present invention provides a heat treatment process optimization method for heat-treatable strengthening aluminum alloy based on phase calculation, which combines the heat treatment process parameters of the heat-treatable strengthening aluminum alloy with Jmatpro software to ensure the accuracy of material performance calculation, and can relatively accurately calculate the TTT curve, CCT curve and equilibrium phase content of the heat-treatable strengthening aluminum alloy, and can quickly determine the heat treatment process parameters of the alloy, thereby reducing the trial and error cost, improving the test efficiency, and also saving a lot of test time and test costs;

[0024] (2) The present invention calculates the phase components of heat-treatable strengthening aluminum alloys to obtain a curve of the strengthening phase changing with the heat treatment process, which can clearly show the relationship between the phase content and the heat treatment process. It is a simple and easy method for optimizing heat treatment, and has strong theoretical support. It does not require a large number of experiments and performance tests, which greatly saves time, improves efficiency, and reduces costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 is the TTT curve of the Al-Zn-Mg-Cu aluminum alloy of Example 1;

[0027] Figure 2is the CCT curve of the Al-Zn-Mg-Cu aluminum alloy of Example 1;

[0028] Figure 3 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 1 after quenching at 475°C and 100°C;

[0029] Figure 4 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 1 after quenching at 475°C and 120°C;

[0030] Figure 5 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 1 after quenching at 475°C and 140°C;

[0031] Figure 6 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 1 after quenching at 475°C and 160°C;

[0032] Figure 7 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 1 after quenching at 475°C and 180°C;

[0033] Figure 8 is the TTT curve of the Al-Zn-Mg-Cu aluminum alloy of Example 4;

[0034] Fig. 9 is the CCT curve of the Al-Zn-Mg-Cu aluminum alloy of Example 4;

[0035] Fig.10 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 4 after quenching at 477°C and 50°C;

[0036] Fig.11 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 4 after quenching at 477°C and 80°C;

[0037] Fig.12 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 4 after quenching at 477°C and 110°C;

[0038] Fig.13 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 4 after quenching at 477°C and 140°C;

[0039] Fig.14 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 4 after quenching at 477°C and 170°C;

[0040] Fig.15 This is the precipitation phase curve of the Al-Zn-Mg-Cu aluminum alloy of Example 4 after quenching at 477°C and then at 200°C.

[0041] Fig.16 is the TTT curve of the Al-Cu-Mg aluminum alloy of Example 5;

[0042] Fig.17 is the CCT curve of the Al-Cu-Mg aluminum alloy of Example 5;

[0043] Fig.18 This is the precipitation phase curve of the Al-Cu-Mg aluminum alloy of Example 5 after quenching at 477°C and 50°C;

[0044] Fig.19 This is the precipitation phase curve of the Al-Cu-Mg aluminum alloy of Example 5 after quenching at 477°C and 100°C;

[0045] Fig. 20 This is the precipitation phase curve of the Al-Cu-Mg aluminum alloy of Example 5 after quenching at 477°C and 150°C;

[0046] Fig.21 This is the precipitation phase curve of the Al-Cu-Mg aluminum alloy of Example 5 after quenching at 477°C and 200°C; DETAILED DESCRIPTION

[0047] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0048] Example 1

[0049] A heat treatment optimization method for Al-Zn-Mg-Cu aluminum alloy based on phase calculation, the specific process is as follows:

[0050] (1) Determine the element composition and content of an Al-Zn-Mg-Cu aluminum alloy, wherein the alloy specifically comprises the following components in parts by weight: Zn 5.7%, Mg 2.3%, Cu 1.6%, Mn 0.05%, Cr 0.24%, Fe 0.2%, Si 0.15%, and the balance being Al and unavoidable impurities;

[0051] (2) Using Jmatpro software, call the TTT / CCT diagrams program under the Phase transformation module, input the elements and contents in step (1) into the software, select the TTT curve and CCT curve options to be calculated, select the components in the Al-Zn-Mg-Cu aluminum alloy, the components include S phase, T phase, S' phase, GP zone, η' phase and MgZn2 phase, then set the initial calculation temperature to 500 °C, and calculate its TTT curve and CCT curve;

[0052] (3) After the calculation is completed, the TTT curve and CCT curve are output. Figure 1 , Figure 2 The solution temperature range and solution transfer time are obtained through the TTT curve, and the quenching cooling rate is calculated through the CCT curve;

[0053] Figure 1 In the TTT curve, the starting transformation temperature of the GP zone is the lowest, which is 175°C, and the nose temperature and the corresponding incubation time are 140°C and 5.68s respectively; the nose temperatures of the other phases η' phase, S' phase, MgZn2 phase, S phase, and T phase increase in turn, which are 320°C, 318°C, 360°C, 345°C, and 375°C, respectively, and the corresponding incubation times are 23.4s, 50.4s, 720s, 1044s, and 1080s respectively; in addition, it can be seen from the curve that the highest incubation temperature is 454°C of the S phase, the solid solution temperature is greater than the highest incubation temperature of the S phase, and the solid solution transfer time is less than the incubation time of the GP zone;

[0054] Figure 2 The CCT curve diagram in the figure comprehensively reflects the relationship between the phase transformation, temperature and time during the continuous cooling transformation of the alloy, which can provide an important reference for the design of aluminum alloy heat treatment process. Figure 1 , select 475℃ as the solution temperature as a point on the ordinate of the CCT curve, which is (0,475), and then select the leftmost point of the curve in the CCT graph, which is (x2,y2), and calculate the critical cooling rate according to the following formula:

[0055] V K =|(y2-y1) / (x2-0)|

[0056] In this embodiment, V K is the critical cooling rate, y 1＝ 475℃, x2=34.7s, y 2＝ 31℃.

[0057] According to the above formula, the critical cooling rate of Al-Zn-Mg-Cu aluminum alloy without precipitation phase is 12.8℃ / s;

[0058] Combined with the CCT curve and TTT curve, when Al-Zn-Mg-Cu aluminum alloy is subjected to solution treatment, the solution temperature should be greater than 454℃, the solution transfer time should be less than 5.68s, and the cooling rate of solution quenching should be greater than 12.8℃ / s, which can inhibit the precipitation of other phases and thus obtain a supersaturated solid solution.

[0059] (4) Using Jmatpro software, call the Isothermal program under the Phase transformation module; set the solution temperature to 475°C, and then set the preset aging temperatures to 100°C, 120°C, 140°C, 160°C, and 180°C; select the components in the Al-Zn-Mg-Cu aluminum alloy, which include S phase, T phase, S' phase, GP zone, η' phase, and MgZn2 phase; calculate the change curves of each phase at different aging temperatures with time when the solution temperature is 475°C, and determine the aging temperature and aging time suitable for the aluminum alloy in combination with the performance requirements of the heat-treatable aluminum alloy to be optimized;

[0060] The curves of the phase changes with time at different aging temperatures obtained in this step when the solution temperature is 475°C are as follows: Figure 3-Figure 7 As shown in the figure, by comparing and analyzing the precipitation amount of each phase at different aging temperatures and combining the performance requirements of aluminum alloy, the optimal aging process is determined. Figure 3-Figure 7 It can be seen that the aging temperature can significantly increase the precipitation rate of each phase; when the aging temperature is 100℃, the GP zone content is very high. With the increase of aging temperature, the GP zone content gradually decreases, and when the temperature is higher than 180℃, the GP zone disappears, while the precipitation time of the metastable phase η' phase and S' phase is shortened, and the precipitation rate increases; when the aging temperature is 160℃, the precipitation curves of the equilibrium phase T phase and MgZn2 phase rise significantly, and the content is higher than that of the GP zone, but the content is lower than that of the aging strengthening phase η', and continues to increase with the increase of aging temperature; when aging at 180℃, there is no GP zone, and the MgZn2 phase increases rapidly. At this time, the precipitated phase in the alloy is coarse, over-aging occurs, and the performance of the alloy is reduced; this is because the aging kinetics is controlled by the diffusion of solute atoms, and temperature is the most important factor affecting the atomic diffusion coefficient. The higher the aging temperature, the greater the diffusion coefficient of the solute atoms, and the faster the decomposition rate of the supersaturated solid solution; the more the precipitated phases, the finer the particles, and the more uniform the distribution, the better the strengthening effect on the matrix. In addition, when the aging temperature is 120℃, the precipitation amount of η' phase is the highest, but the time required for complete aging is also the longest. With the increase of temperature, the precipitation rate of η' phase increases. At 160℃, the precipitation amount of η' phase is large, and the required aging time is short. Since η' phase is the main strengthening phase of alloy aging, too much GP zone and equilibrium phase will affect the strengthening effect of precipitation phase. In order to obtain higher strength, the optimal aging temperature is determined to be 160℃ and the aging time is 4h-8h.

[0061] (5) Through the calculation results of steps (3) and (4), the optimal heat treatment process including solution temperature, solution transfer time, quenching rate, aging temperature and aging time suitable for the heat-treatable strengthening aluminum alloy to be optimized is obtained, that is, the appropriate heat treatment process under the alloy composition is solution temperature ≥ 475°C, solution transfer time less than 5.68s, quenching cooling rate greater than 12.8°C / s, aging temperature of 160°C, and aging time of 4h-8h, which can make the material have higher strength.

[0062] The TTT curve is the phase precipitation of the material at this temperature with the extension of time. To ensure that the alloy obtains a supersaturated solid solution, the solid solution temperature must be greater than the top of the TTT curve, and the solid solution transfer time must be less than the leftmost side of the TTT curve; the CCT curve is the phase transformation in the structure of the material during the cooling process. Similarly, to obtain a supersaturated solid solution, the cooling rate must avoid the leftmost curve of the CCT. Therefore, based on a certain holding temperature (that is, a certain point) on the ordinate, to a point on the leftmost side of the CCT curve, the slope of the line connecting the two points is the critical cooling rate. The cooling rate of the material must be greater than the critical cooling rate.

[0063] Example 2

[0064] A heat treatment optimization method for Al-Zn-Mg-Cu aluminum alloy based on phase calculation is different from Example 1 in that: in order to make the material have higher corrosion resistance, the suitable heat treatment process under the alloy composition is 475°C solid solution, solid solution transfer time less than 5.68s, quenching cooling rate greater than 12.8°C / s, aging temperature of 180°C, and aging time greater than 10h, which can make the GP zone in the material disappear, increase the S phase and MgZn2 phase, and make the material have excellent corrosion resistance.

[0065] Example 3

[0066] A heat treatment optimization method for Al-Zn-Mg-Cu aluminum alloy based on phase calculation is different from Example 1 in that: in order to make the material have good comprehensive properties, the suitable heat treatment process under the alloy composition is 475°C solid solution, solid solution transfer time is less than 5.68s, quenching cooling rate is greater than 12.8°C / s, aging temperature is 160°C, and aging time is 10h, so that GP zone, η' phase, S phase, and MgZn2 phase can exist in the material at the same time, so that the material has good comprehensive properties.

[0067] Example 4

[0068] A heat treatment optimization method for Al-Zn-Mg-Cu aluminum alloy based on phase calculation, the specific process is as follows:

[0069] (1) Determine the element composition and content of the Al-Zn-Mg-Cu aluminum alloy, wherein the alloy specifically comprises the following components in parts by weight: Zn 6.9%, Mg 2.7%, Cu 2.5%, Mn 0.1%, Cr 0.04%, Zr 0.15%, Fe 0.15%, Si 0.12%, and the balance being Al and unavoidable impurities;

[0070] (2) Using Jmatpro software, call the TTT / CCT diagrams program under the Phase transformation module, input the elements and contents in step (1) into the software, select the TTT curve and CCT curve options to be calculated, select the components in the Al-Zn-Mg-Cu aluminum alloy, the components include S phase, T phase, S' phase, GP zone, η' phase and MgZn2 phase, then set the initial calculation temperature to 500 °C, and calculate its TTT curve and CCT curve;

[0071] (3) After the calculation is completed, the TTT curve and CCT curve are output. Figure 8 , Fig. 9 The solution temperature range and solution transfer time are obtained through the TTT curve, and the quenching cooling rate is calculated through the CCT curve;

[0072] Figure 8 The starting transformation temperature of the GP zone in the TTT curve is the lowest and cannot be avoided, so the incubation time of the η' phase, 14.4s, is selected as the solid solution transfer time; the highest incubation temperature is 476℃ of the S phase, the solid solution temperature is greater than the highest incubation temperature of the S phase, and the solid solution transfer time is less than the incubation time of the GP zone;

[0073] Fig. 9 The CCT curve diagram in the figure comprehensively reflects the relationship between the phase transformation, temperature and time during the continuous cooling transformation of the alloy, and can provide an important reference for the design of the heat treatment process of aluminum alloy. 477℃ is selected as the solution temperature and the leftmost point of the curve in the CCT diagram. According to the formula:

[0074] V k =|(y2-y1) / (x2-0)|

[0075] In this embodiment, V k is the critical cooling rate, y1 = 477 °C, x2 = 22.17 s, y2 = 30 °C;

[0076] Combined with the above formula, it is calculated that the critical cooling rate of the Al-Zn-Mg-Cu aluminum alloy without precipitation phase is 20.16℃ / s;

[0077] Combined with the CCT curve and TTT curve, when Al-Zn-Mg-Cu aluminum alloy is subjected to solution treatment, the solution temperature should be greater than 477℃, the solution transfer time should be less than 14.4s, and the cooling rate of solution quenching should be greater than 20.16℃ / s, which can inhibit the precipitation of other phases and thus obtain a supersaturated solid solution.

[0078] (4) Using Jmatpro software, call the Isothermal program under the Phase transformation module; set the solution temperature to 477°C, and then set the preset aging temperatures to 50°C, 80°C, 110°C, 40°C, 170°C, and 200°C respectively; select the components in the Al-Zn-Mg-Cu aluminum alloy, which include S phase, T phase, S' phase, GP zone, η' phase, and MgZn2 phase, and calculate the change curves of each phase with time at different aging temperatures when the solution temperature is 477°C, and determine the aging temperature and aging time suitable for the aluminum alloy in combination with the performance requirements of the heat-treatable aluminum alloy to be optimized;

[0079] The curves of the phase changes with time at different aging temperatures obtained in this step when the solution temperature is 477°C are as follows: Figure 10-15 , combined with Figure 10-15 It can be seen that the aging temperature can significantly increase the precipitation rate of each phase; when the aging temperature is 50℃, the GP zone content is very high, and there is only the GP zone. With the increase of the aging temperature, the GP zone content gradually decreases, and when the temperature is higher than 200℃, the GP zone disappears, while the precipitation time of the metastable phase η' phase and S' phase is shortened, and the precipitation rate increases; when the aging temperature is 140℃, the precipitation amount of η' phase is the highest. Since η' phase is the main strengthening phase of alloy aging, too much GP zone and other phases will affect the strengthening effect of the precipitation phase. In order to obtain excellent strength, the optimal aging temperature is determined to be 140℃ and the aging time is 8-10h;

[0080] (5) Through the calculation results of steps (3) and (4), the optimal heat treatment process including solution temperature, solution transfer time, quenching rate, aging temperature and aging time suitable for the heat-treatable strengthening aluminum alloy to be optimized is obtained, that is, the appropriate heat treatment process under the alloy composition is solution temperature ≥ 477°C, solution transfer time less than 14.4s, quenching cooling rate greater than 20.16°C / s, aging temperature of 140°C, and aging time of 8-10h, which can make the material have higher strength.

[0081] Example 5

[0082] An Al-Cu-Mg aluminum alloy heat treatment optimization method based on phase calculation, the specific process is as follows:

[0083] (1) Determining the element composition and content of an Al-Cu-Mg aluminum alloy, wherein the alloy specifically comprises the following components in parts by weight: Cu 3.6%, Mg 1.3%, Mn 0.7%, Ti 0.05%, Zr 0.11%, and the balance being Al and unavoidable impurities;

[0084] (2) Using Jmatpro software, call the TTT / CCT diagrams program under the Phase transformation module, input the elements and contents in step (1) into the software, select the TTT curve and CCT curve options to be calculated, select the components in the Al-Zn-Mg-Cu aluminum alloy, the components include S phase, Al2Cu phase, S' phase, θ' phase, GP zone, then set the initial calculation temperature to 500 °C, and calculate its TTT curve and CCT curve;

[0085] (3) After the calculation is completed, the TTT curve and CCT curve are output. Fig.16 , Fig.17 The solution temperature range and solution transfer time are obtained through the TTT curve, and the quenching cooling rate is calculated through the CCT curve;

[0086] Fig.16 In the TTT curve, the starting transformation temperature of the GP zone is the lowest, which is 192°C, and the nose temperature and the corresponding incubation time are 160°C and 12.8s respectively; the nose temperatures of the other phases, θ' phase, S' phase, Al2Cu phase, and S phase increase in turn; in addition, it can be seen from the curve that the highest incubation temperature is 474°C of the S phase, the solid solution temperature is greater than the highest incubation temperature of the S phase, and the solid solution transfer time is less than the incubation time of the GP zone;

[0087] Fig.17 The CCT curve diagram in the figure comprehensively reflects the relationship between the phase transformation, temperature and time during the continuous cooling transformation of the alloy, which can provide an important reference for the design of aluminum alloy heat treatment process. Fig.16 , select 490℃ as the solution temperature as a point on the ordinate of the CCT curve, which is (0,490), and then select the leftmost point of the curve in the CCT graph, which is (x2,y2), and calculate the critical cooling rate according to the following formula:

[0088] V k =|(y2-y1) / (x2-0)|

[0089] In this embodiment, V k is the critical cooling rate, y1 = 490 °C, x2 = 84 s, y2 = 30 °C;

[0090] Combined with the above formula, it is calculated that the critical cooling rate of the Al-Cu-Mg aluminum alloy without precipitation phase is 15.33℃ / s;

[0091] According to the CCT curve and TTT curve, when Al-Cu-Mg aluminum alloy is subjected to solution treatment, the solution temperature should be greater than 474℃, the solution transfer time should be less than 12.8s, and the cooling rate of solution quenching should be greater than 15.33℃ / s, which can inhibit the precipitation of other phases and thus obtain a supersaturated solid solution.

[0092] (4) Using Jmatpro software, call the Isothermal program under the Phase transformation module; set the solution temperature to 490°C, and then set the preset aging temperatures to 50°C, 100°C, 150°C, and 200°C respectively; select the components in the Al-Cu-Mg aluminum alloy, which include S phase, Al2Cu phase, S' phase, θ' phase, and GP zone, and calculate the change curves of each phase with time at different aging temperatures when the solution temperature is 490°C, and determine the aging temperature and aging time suitable for the aluminum alloy in combination with the performance requirements of the heat-treatable aluminum alloy to be optimized;

[0093] The curves of the phase changes with time at different aging temperatures obtained in this step when the solution temperature is 490°C are as follows: Figure 18-Figure 21 Under this chemical composition, the strengthening phase of Al-Cu-Mg aluminum alloy is mainly S' phase, combined with Figure 18-Figure 21 It can be seen that when the aging temperature is 150℃, the content of S' phase is very high, but if the aging time is greater than 10h, the S' phase will transform into S' phase, reducing the strengthening effect of the S' phase precipitation phase. In order to obtain excellent strength, the optimal aging temperature is determined to be 150℃ and the aging time is 8-10h;

[0094] (5) Through the calculation results of steps (3) and (4), the optimal heat treatment process including solution temperature, solution transfer time, quenching rate, aging temperature and aging time suitable for the heat-treatable strengthening aluminum alloy to be optimized is obtained, that is, the appropriate heat treatment process under the alloy composition is solution temperature ≥ 474°C, solution transfer time less than 12.8s, quenching cooling rate greater than 15.33°C / s, aging temperature of 150°C, and aging time of 8-10h, which can make the material have higher strength.

[0095] The aluminum alloy profiles obtained in Examples 1-5 were subjected to mechanical property tests and exfoliation corrosion performance tests, and the results are shown in Table 1. Table 1 shows the mechanical property and exfoliation corrosion performance test results of Examples 1-5.

[0096] Table 1 Performance test results

[0097]

[0098] The test results in Table 1 are compared and analyzed with the optimization process of the above-mentioned Examples 1-5, which are basically consistent with the performance change trend of the alloy analyzed in the optimization process. The optimization method of the present invention can provide a reference for determining the heat treatment process of a new alloy, reduce the trial and error cost, and improve the test efficiency.

[0099] It should be noted that some parts not described in the present invention can be implemented by adopting or drawing on existing technologies.

[0100] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for optimizing heat treatment process of heat-treatable and strengthened aluminum alloy based on phase calculation, characterized in that: Includes steps: (1) Determine the element composition and content of the heat-treatable and strengthened aluminum alloy to be optimized; (2) Input the composition elements and contents of the heat-treatable aluminum alloy to be optimized in step (1) into the Jmatpro software, select the components in the aluminum alloy, set the initial calculation temperature, and calculate its TTT curve and CCT curve; (3) After the calculation is completed, the TTT curve and CCT curve are output, and the solution temperature range and solution transfer time are obtained through the TTT curve, and the quenching cooling rate is calculated through the CCT curve; (4) according to the solution temperature range obtained in step (3), the solution temperature is set in the Jmatpro software, and the preset aging temperature is set, and then the components in the aluminum alloy are selected, and the change curves of each phase with time at different aging temperatures are calculated, and the aging temperature and aging time suitable for the aluminum alloy are determined in combination with the performance requirements of the heat-treatable aluminum alloy to be optimized; (5) Based on the calculation results of steps (3) and (4), the optimal heat treatment process including solution temperature, solution transfer time, quenching rate, aging temperature and aging time suitable for the heat-treatable aluminum alloy to be optimized is obtained.

2. The method for optimizing heat treatment process of heat-treatable and strengthened aluminum alloy based on phase calculation according to claim 1, characterized in that: The heat-treatable and strengthened aluminum alloy in step (1) is one of Al-Cu-Mg alloy and Al-Zn-Mg-Cu alloy.

3. The method for optimizing heat treatment process of heat-treatable and strengthened aluminum alloy based on phase calculation according to claim 2, characterized in that: When the heat-treatable strengthening aluminum alloy in step (1) is an Al-Cu-Mg alloy, the components in the Al-Cu-Mg alloy in steps (2) and (3) are set to include S phase, Al2Cu phase, S' phase, θ' phase, and GP region; When the heat-treatable and strengthened aluminum alloy in step (1) is an Al-Zn-Mg-Cu alloy, the components in the Al-Zn-Mg-Cu alloy in steps (2) and (3) are set to include S phase, T phase, S' phase, GP zone, η' phase and MgZn2 phase.

4. The method for optimizing heat treatment process of heat-treatable and strengthened aluminum alloy based on phase calculation according to claim 1, characterized in that: The initial calculation temperature set in step (2) is 500-550°C.

5. The method for optimizing heat treatment process of heat-treatable and strengthened aluminum alloy based on phase calculation according to claim 1, characterized in that: The quenching cooling rate in step (3) is obtained according to the critical cooling rate of the component, and the calculation process is as follows: Set two coordinates, one of which is the point on the ordinate, representing the solution temperature, which is (0, y1) on the CCT diagram, and the other is the point on the far left of the CCT diagram (x2, y2). The critical cooling rate V of the alloy k The calculation formula is: <h2 style=";text-align:left;direction:ltr">V<h2 style=";text-align:left;direction:ltr"> k <h2 style=";text-align:left;direction:ltr"> (y2-y1) / (x2-0)| 6. The method for optimizing heat treatment process of heat-treatable and strengthened aluminum alloy based on phase calculation according to claim 1, characterized in that: The lower limit of the preset solution temperature in step (4) is the highest point in the TTT curve, and the upper limit is the overburning temperature of the heat-treatable strengthened aluminum alloy.

7. The method for optimizing heat treatment process of heat-treatable and strengthened aluminum alloy based on phase calculation according to claim 1, characterized in that: The preset aging temperature in step (4) is room temperature to 300°C.

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