Homogenization process of ultra-high strength aluminum alloy based on pore evolution and thermal coupling simulation model

Abstract

The application discloses a homogenization process for super-high-strength aluminum alloy based on a pore evolution and thermal coupling simulation model and belongs to the technical field of metal heat treatment. In view of the problems of poor plasticity, high porosity and difficult organization regulation of a large-size super-high-strength aluminum alloy ingot prepared by spray forming, the application adopts a three-stage ladder homogenization, hot compression densification, thermal coupling simulation and two-stage solid solution and aging integrated process, establishes a quantitative model coupled with an Arrhenius constitutive equation, dynamic recrystallization and pore evolution, realizes the cooperative regulation of coarse precipitated phase dissolution, pore closure and organization refinement, shortens the homogenization cycle by more than 30%, reduces the residual porosity to less than 0.3%, increases the elongation by more than 50%, and is stable and excellent in mechanical properties. The simulation precision R is greater than or equal to 0.95, and the application is suitable for the preparation of large-size super-high-strength aluminum alloy components.

Description

Technical Field

[0001] This invention belongs to the field of heat treatment and plastic forming technology of metallic materials, specifically involving a homogenization process for ultra-high strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling. It is particularly suitable for microstructure control and defect elimination of large-size AlZnMgCuZr(Sc) series ultra-high strength aluminum alloy ingots formed by spray forming. Background Technology

[0002] Spray-formed large-size ultra-high-strength aluminum alloys have advantages such as uniform composition, fine grains, no macroscopic segregation, and high degree of alloying, and are widely used in key load-bearing components in aerospace. However, these ingots generally suffer from problems such as poor plasticity, complex porosity defects, insufficient dissolution of coarse precipitates, difficulty in suppressing static recrystallization, long homogenization cycle, and high energy consumption.

[0003] Traditional homogenization processes often employ single-stage or simple two-stage insulation, lacking quantitative characterization of pore evolution and accurate simulation of thermo-mechanical coupling deformation. This makes it difficult to achieve coordinated control of microstructure homogenization and pore closure, resulting in subsequent forming processes that are prone to cracking, exhibit large performance fluctuations, and lack stability.

[0004] Current technologies lack an integrated simulation model that couples Arrhenius constitutive model, dynamic recrystallization, and porosity evolution, making it impossible to predict and optimize hot working parameters. This results in poor process repeatability and high costs. Therefore, developing an efficient, accurate, and simulable homogenization process for ultra-high strength aluminum alloys has significant engineering value. Summary of the Invention

[0005] This invention addresses the problems of poor plasticity, high porosity, and difficulty in microstructure control in large-scale ultra-high-strength aluminum alloy ingots produced by spray forming. It provides a homogenization process for ultra-high-strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling, significantly improving the stability of the material's plasticity and mechanical properties. The homogenization process provided by this invention reduces the total homogenization time by more than 30%, resulting in energy savings and efficiency improvements; reduces residual porosity from 1%-2% to below 0.05%; increases elongation by more than 30%; and achieves tensile strength ≥800 MPa. The simulation model has high accuracy, and the process is predictable, replicable, and scalable for production. It also suppresses static recrystallization, resulting in a uniform microstructure and complete dissolution of coarse precipitates.

[0006] A homogenization process for ultra-high strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling includes the following steps: Composition: By mass percentage: Zn 10-12%, Mg 1.8-3%, Cu 1.1-2.2%, Zr 0.08-0.25%, Sc 0-0.2%, total impurities ≤0.15%, balance Al; Spray forming: Obtain large-size billets with a density of 98%–99% and an initial porosity of 1%–2%; Homogenization treatment: Two-stage homogenization is used for Zr-containing alloys, and three-stage homogenization is used for Zr+Sc-containing alloys, with a heating rate of 30-40℃ / h; Hot compression deformation: temperature 300~450℃, strain rate 0.01~10 s. -1 True strain 0.2–0.8; Thermo-coupling simulation: Based on the Arrhenius constitutive model, dynamic recrystallization model, and pore evolution model, predict stress, microstructure, and pore evolution; A two-stage solution treatment followed by aging treatment is performed to obtain a uniform microstructure with a high strength and high toughness.

[0007] Preferably, the two-stage homogenization is as follows: Stage 1: 420-440℃, heat preservation for 6-8 h; Stage 2: 460-475℃, heat preservation for 8-12 h.

[0008] Preferably, the three-stage homogenization is as follows: Stage 1: 410-430℃, heat preservation for 5-7 h; Stage 2: 440-460℃, heat preservation for 6-8 h; Stage 3: 465-475℃, heat preservation for 8-12 h.

[0009] Preferably, the strain-compensated Arrhenius constitutive model is adopted: (1) (2) In the formula: Strain rate; For rheological stress; Q is the activation energy for thermal deformation; R = 8.314 J·mol -1 ; T is the absolute temperature; A, α, and n are material constants; Z is the parameter for ZenerHollomon.

[0010] Preferred dynamic recrystallization volume fraction model: (3) In the formula: The critical strain; Peak strain; c and d are material constants.

[0011] Preferred porosity evolution model: In the formula: f0 is the initial porosity; Porosity under strain ε; k is the pore closure coefficient.

[0012] Preferably, the two-stage solution treatment is as follows: Stage 1: 450-460℃, 30-120 min; Stage 2: 465-475℃, 30-90 min; heated in a salt bath furnace and quenched in water.

[0013] Preferably, the aging time is 110-150℃, and the heat preservation time is 10-24 h.

[0014] Preferably, the simulation accuracy meets the following requirements: correlation coefficient R ≥ 0.95, and average relative error AARE ≤ 10%.

[0015] Beneficial effects of this invention: The evolution of coarse precipitates and Al3X dispersed phase precipitation in spray-formed aluminum alloys containing Zr and Zr and Sc under different homogenization processes was studied. Two-stage and three-stage homogenization processes optimized for the two alloys were proposed, which effectively improved the microstructure and suppressed static recrystallization. The evolution of porosity defects in the spray-formed aluminum alloys with deformation was analyzed by XCT scanning under different hot compression conditions, laying the foundation for subsequent porosity defect elimination.

[0016] Hot compression experiments and microstructure characterization under conditions of 300-450 °C and 0.01-10 / s revealed the subgrain rotation dynamic recrystallization mechanism of ultra-high strength aluminum alloys. Coupled with crystal plasticity simulation methods, a continuous dynamic recrystallization model of ultra-high strength aluminum alloys was established, predicting the stress and dynamic recrystallization evolution under hot compression conditions. A method based on macroscopic thermo-mechanical coupling simulation discretization and microscopic dynamic recrystallization calculation integration was proposed, realizing the prediction of dynamic recrystallization structure under non-uniform hot deformation.

[0017] (3) Friction correction and temperature correction were performed using the hot compressive stress-strain curve data of ultra-high strength aluminum alloy. An Arrhenius constitutive model that can comprehensively consider the compensation of three deformation parameters, namely deformation temperature, strain rate and strain, was established. The accuracy correlation coefficient R≥0.95 and the average relative error AARE≤10%. Based on the Prasad instability criterion and microstructure analysis, a three-dimensional processing instability diagram and a dynamic recrystallization diagram were established, and the hot working tolerance was determined.

[0018] (4) The homogenization process of ultra-high strength aluminum alloy provided by the present invention reduces the total homogenization time by more than 30%, saving energy and increasing efficiency; the residual porosity is reduced from 1%-2% to less than 0.05%; the elongation is increased by more than 30% and the tensile strength is ≥800MPa; the simulation model has high accuracy, the process is predictable, replicable and can be scaled up for production; static recrystallization is suppressed, the structure is uniform, and the coarse precipitates are completely dissolved. Attached Figure Description

[0019] Figure 1. Process flow diagram of the present invention. Detailed Implementation

[0020] The present invention will be described in detail below with reference to embodiments and comparative examples. However, the present invention is not limited to the following embodiments. Example 1

[0021] 1. Raw material composition (wt%) is as follows: Zn: 11.3; Mg: 2.1; Cu: 1.6; Zr: 0.12; Sc: 0.15; Total impurities: ≤0.15; Balance: Al.

[0022] 2. The billet is formed by spray forming, with a density of 98.1% and an initial porosity of f0=1.9%.

[0023] 3. Homogenization process: Two-stage homogenization: Stage 1: 430℃, holding for 7 h; Stage 2: 470℃, holding for 10 h. Heating rate: 40℃ / h.

[0024] 4. Hot compression parameters: temperature 400℃, strain rate 0.1s -1 True strain 0.6.

[0025] 5. Model parameters: Q=185000J / mol; A=1.2×1012 s-1; α = 0.015 MPa⁻¹; n=4.8; k=3.2.

[0026] 6. Formula calculation: (1) Calculation of Z parameters: Porosity calculation: 7. Solution aging: Level 1: 455℃, 60 min; Level 2: 470℃, 45 min; Salt bath furnace heating at 120℃ for 18 h, water quenching.

[0027] 8. Test Results: Simulation accuracy: R=0.976, AARE=7.2%. Porosity: 0%. Mechanical properties: R m =805 MPa; R p0.2 =748 MPa; A=7% Example 2

[0028] 1. Raw material composition (wt%): Zn: 11.8; Mg: 2.6; Cu: 1.8; Zr: 0.18; Sc: 0.10; Total impurities: ≤0.15; Balance: Al.

[0029] 2. The billet is formed by spray forming, with a density of 98.5% and an initial porosity of f0=1.5%.

[0030] 3. Homogenization process: three-stage homogenization: stage 1: 420℃, holding for 6 h; stage 2: 450℃, holding for 7 h; stage 3: 470℃, holding for 10 h; heating rate 40℃ / h.

[0031] 4. Hot compression parameters: temperature 420℃, strain rate 1s -1 True response .

[0032] 5. Model parameters: Q = 192000 J / mol; k = 3.6.

[0033] Formula for calculating porosity evolution: 7. Solution aging: Level 1: 455℃, 60 min; Level 2: 475℃, 45 min; Salt bath furnace heating at 120℃ for 18 h, followed by water quenching.

[0034] 8. Test Results Simulation accuracy: R=0.981, AARE=6.5%; Porosity: 0%; Mechanical properties: R m =810MPa; R p0.2 =752MPa; A=6.5% Example 3

[0035] 1. Raw material composition (wt%) is as follows: Zn: 11.3; Mg: 2.1; Cu: 1.6; Zr: 0.12; Sc: 0.15; Total impurities: ≤0.15; Balance: Al.

[0036] 2. The billet is formed by spray forming, with a density of 98.4% and an initial porosity of f0=1.6%.

[0037] 3. Homogenization process: three-stage homogenization: stage 1: 425℃, holding for 6 hours; stage 2: 455℃, holding for 7 hours; stage 3: 475℃, holding for 9 hours; heating rate 40℃ / h.

[0038] 4. Thermal compression parameters: Temperature 380℃, strain rate 10s -1 True response .

[0039] 5. Model parameters: Q = 188000 J / mol; k = 3.0.

[0040] 6. Formula calculation: (1) Z parameters: Porosity: Solution aging: First-stage solution treatment: 450℃, 60 min; Second-stage solution treatment: 470℃, 45 min; Salt bath furnace heating at 130℃ for 16 h; Water quenching.

[0041] 8. Test Results Simulation accuracy: R=0.968, AARE=8.1%; Porosity: 0%; Mechanical properties: Rm=808 MPa; Rp0.2=746 MPa; A=6.8%.

[0042] Comparative Example 1. The raw material composition is the same as in Example 1.

[0043] 2. Traditional single-stage homogenization process: 460℃×24 h; optimization without thermo-coupling; densification without thermal compression; conventional single-stage solution aging.

[0044] 3 Results Porosity: 0.1% Mechanical properties: Rm = 725 MPa; Rp0.2 = 680 MPa; A = 6.3% Structure: There are many coarse residual phases, obvious grain boundary segregation, high degree of recrystallization, and large fluctuations in performance.

[0045] Test Data Summary Table The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

[0046] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

Claims

1. A homogenization process for ultra-high strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling, characterized in that, Includes the following steps: Composition: By mass percentage: Zn 10-12%, Mg 1.8-3%, Cu 1.1-2.2%, Zr 0.08-0.25%, Sc 0-0.2%, total impurities ≤0.15%, balance Al; Spray forming: Obtain large-size billets with a density of 98%–99% and an initial porosity of 1%–2%; Homogenization treatment: Two-stage homogenization is used for Zr-containing alloys, and three-stage homogenization is used for Zr+Sc-containing alloys, with a heating rate of 30-40℃ / h; Hot compression deformation: temperature 300~450℃, strain rate 0.01~10 s. -1 True strain 0.2–0.8; Thermo-coupling simulation: Based on the Arrhenius constitutive model, dynamic recrystallization model, and pore evolution model, predict stress, microstructure, and pore evolution; A two-stage solution treatment followed by aging treatment is performed to obtain a uniform microstructure with a high strength and high toughness.

2. The homogenization process for ultra-high strength aluminum alloy based on a simulation model of pore evolution and thermo-mechanical coupling according to claim 1, characterized in that, The two-stage homogenization process is as follows: Stage 1: 420-440℃, heat preservation for 6-8 hours; Level 2: 460~475℃, keep warm for 8~12 hours.

3. The homogenization process for ultra-high strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling as described in claim 1, characterized in that, The three-stage homogenization process is as follows: Stage 1: 410–430℃, heat preservation for 5–7 h; Level 2: 440~460℃, keep warm for 6~8 hours; Level 3: 465~475℃, keep warm for 8~12 hours.

4. The homogenization process for ultra-high strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling according to claim 1, characterized in that, The strain-compensated Arrhenius constitutive model is adopted: (1) (2) In the formula: Strain rate; For rheological stress; Q is the activation energy for thermal deformation; R = 8.314 J mol -1 ; T is the absolute temperature; A, α, and n are material constants; Z is the ZenerHollomon parameter.

5. The homogenization process for ultra-high strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling according to claim 1, characterized in that, Dynamic recrystallization volume fraction model: (3) In the formula: The critical strain; Peak strain; c and d are material constants.

6. The homogenization process for ultra-high strength aluminum alloy based on a simulation model of pore evolution and thermo-mechanical coupling according to claim 1, characterized in that, Porosity evolution model: In the formula: f0 is the initial porosity; Porosity under strain ε; k is the pore closure coefficient.

7. The homogenization process for ultra-high strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling according to claim 1, characterized in that, The two-stage solution treatment is as follows: Stage 1: 450–460℃, 30–120 min; Level 2: 465~475℃, 30~90 min; heated in a salt bath furnace, then quenched in water.

8. The homogenization process for ultra-high strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling according to claim 1, characterized in that, The aging time is: 110~150℃, heat preservation for 10~24 h.

9. The homogenization process for ultra-high strength aluminum alloys based on a simulation model of pore evolution and thermo-mechanical coupling according to any one of claims 1 to 8, characterized in that, The simulation accuracy meets the following requirements: correlation coefficient R ≥ 0.95, and average relative error AARE ≤ 10%.

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