A discontinuous temperature gradient heat treatment method for quickly eliminating difficultly soluble phase of Al-Mg alloy

Abstract

This invention relates to a rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys, belonging to the field of aluminum alloy heat treatment. This invention involves rapidly eliminating insoluble phases in Al-Mg alloys from room temperature at a temperature gradient of V... a The rate of increase rises to temperature point T A Reaching temperature point T A Later with V b The rate of increase rises to temperature point T B Reaching temperature point T B Later with V c The rate of increase rises to temperature point T C Reaching temperature point T C Then air cooling is performed; temperature point T A Temperature point T B and temperature point T C Based on the non-equilibrium phase diagram of Al-Mg alloys, the temperature point T is determined. A The selected temperature is within the range of 0–50°C above the precipitation start temperature of the low-melting-point second phase in the non-equilibrium phase diagram of the Al-Mg alloy. Temperature T is defined as... B Select a temperature within the range of 0–50°C above the intermediate melting point and the precipitation start temperature of the second phase in the non-equilibrium phase diagram of Al-Mg alloys. Temperature T is chosen as this temperature point. C The temperature range selected is within ±10℃ of the precipitation start temperature of the high-melting-point second phase in the non-equilibrium phase diagram of Al-Mg alloys. This invention employs a variable-speed, discontinuous temperature gradient homogenization heat treatment, which effectively dissolves the insoluble phase.

Description

Technical Field

[0001] This invention relates to a method for rapidly eliminating discontinuous temperature gradient heat treatment of refractory phases in Al-Mg alloys, belonging to the field of heat treatment of aluminum alloys. Background Technology

[0002] Al-Mg aluminum alloys are widely used in the automotive and shipbuilding industries due to their high strength, good formability, corrosion resistance, and weldability. Since Al-Mg aluminum alloys are typical non-heat-treatable aluminum alloys, a suitable homogenization process is crucial for providing high-quality Al-Mg aluminum alloy billets for subsequent material processing. Homogenization can dissolve the non-equilibrium second phases in as-cast Al-Mg aluminum alloys, significantly eliminating element segregation in the ingot, improving the alloy's machinability, and enhancing the mechanical properties and corrosion resistance of the final product. The refractory phases in the solidification structure of Al-Mg alloys mainly consist of Al(FeMn), Al(FeMnCr), Al(CrMgMn) phases, and Mg2Si phase. Currently, ordinary homogenization processes cannot dissolve these high-temperature stable second phases, and traditional methods of increasing the homogenization temperature easily lead to overheating of the alloy. These coarse, hard, and brittle phases are prone to crack initiation during processing, significantly harming the alloy's formability and overall performance. Summary of the Invention

[0003] To address the problems of Al(FeMn), Al(FeMnCr), Al(CrMgMn) and Mg2Si insoluble phases present in Al-Mg aluminum alloys treated by existing homogenization processes, which affect the alloy's processability, intergranular corrosion susceptibility, fracture toughness and fatigue limit strength, this invention proposes a discontinuous temperature gradient heat treatment method to rapidly eliminate insoluble phases in Al-Mg alloys. This method employs variable-speed discontinuous temperature gradient homogenization heat treatment, which can effectively dissolve and reduce the volume fraction of insoluble phases, spheroidize and reduce the size of blocky insoluble phases, and help prevent crack initiation at the location of insoluble phases during deformation. Furthermore, the non-isothermal process effectively avoids overheating during high-temperature heat treatment.

[0004] A rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys, comprising the following steps:

[0005] Al-Mg alloys were heated from room temperature at V a The rate of increase rises to temperature point T A Reaching temperature point T A Later with V b The rate of increase rises to temperature point T B Reaching temperature point T B Later with V c The rate of increase rises to temperature point T C Reaching temperature point T CThen air cooling is performed;

[0006] The

[0007] The temperature point T A Temperature point T B and temperature point T C The method for determining it includes the following steps:

[0008] (1) The measured chemical composition of Al-Mg aluminum alloy was input into JMatPro software, and the non-equilibrium phase diagram of Al-Mg alloy was calculated using the phase diagram calculation module;

[0009] (2) Determine the temperature point T based on the non-equilibrium phase diagram of Al-Mg alloy. A Temperature point T B and temperature point T C The temperature point T A The selected temperature is within the range of 0–50°C above the precipitation start temperature of the low-melting-point second phase in the non-equilibrium phase diagram of the Al-Mg alloy. Temperature T is defined as... B Select a temperature within the range of 0–50°C above the intermediate melting point and the precipitation start temperature of the second phase in the non-equilibrium phase diagram of Al-Mg alloys. Temperature T is chosen as this temperature point. C Select a temperature range of ±10℃ from the precipitation start temperature of the high-melting-point second phase in the non-equilibrium phase diagram of Al-Mg alloys;

[0010] The low melting point temperature range is 25–300℃, the intermediate melting point temperature range is 300–500℃, and the high melting point temperature range is 500–650℃.

[0011] The V a 500~600℃ / h, V b The temperature is 10–40℃ / h, V c The temperature is 2–10℃ / h.

[0012] Preferably, the V a 500~600℃ / h, V b The temperature is 10–30℃ / h, V c The temperature is 2–8℃ / h.

[0013] More preferably, the V a The temperature is 550–600℃ / h, V b The temperature is 15–25℃ / h, V c The temperature is 3-6℃ / h.

[0014] The beneficial effects of this invention are:

[0015] This invention employs variable-speed, non-isothermal homogenization heat treatment, which can effectively dissolve and reduce the volume fraction of insoluble phases, spheroidize and reduce the size of blocky insoluble phases, thus preventing crack initiation at the location of insoluble phases during deformation. Furthermore, the non-isothermal process effectively avoids overheating during high-temperature heat treatment, while also resulting in the precipitation of obvious dispersed phase particles. Attached Figure Description

[0016] Figure 1 This is a diagram illustrating the discontinuous temperature gradient heat treatment process for Al-Mg alloys according to the present invention.

[0017] Figure 2 The non-equilibrium phase diagrams of the Al-Mg alloys in Examples 1-5 are calculated based on the measured compositions.

[0018] Figure 3 To ensure no difference between Comparative Example 1 and Examples 1-5, at least 10 scanning electron microscope images of the insoluble phase were selected for statistical results.

[0019] Figure 4 The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in Example 1 is shown in the scanning electron microscope.

[0020] Figure 5 The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in Example 2 is shown in the scanning electron microscope.

[0021] Figure 6 The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in Example 3 is shown in the scanning electron microscope.

[0022] Figure 7 The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in Example 4 is shown in the scanning electron microscope.

[0023] Figure 8 The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in Example 5 is shown in the scanning electron microscope.

[0024] Figure 9 This is a scanning electron microscope tissue obtained by isothermal heat treatment in Comparative Example 1.

[0025] Figure 10 The non-equilibrium phase diagram of the Al-Mg alloy calculated based on the measured composition in Example 6;

[0026] Figure 11 The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in Example 6 is shown in the scanning electron microscope.

[0027] Figure 12 The non-equilibrium phase diagram of the Al-Mg alloy calculated based on the measured composition in Example 7;

[0028] Figure 13 The scanning electron microscope microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in Example 7 is shown. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0030] Example 1: A rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys (see...) Figure 1 The specific steps are as follows:

[0031] (1) The measured chemical composition of Al-Mg aluminum alloy was input into JMatPro software, and the non-equilibrium phase diagram of Al-Mg alloy was calculated using the phase diagram calculation module (see Figure 2 The measured chemical composition of Al-Mg aluminum alloy is shown in Table 1.

[0032] Table 1 Measured chemical composition of Al-Mg aluminum alloy

[0033] (2) Determine the temperature point T based on the non-equilibrium phase diagram of Al-Mg alloy. A Temperature point T B and temperature point T C The temperature point T A The selected temperature is within the range of 0–50°C above the precipitation start temperature of the low-melting-point second phase in the non-equilibrium phase diagram of the Al-Mg alloy. Temperature T is defined as... B Select a temperature within the range of 0–50°C above the intermediate melting point and the precipitation start temperature of the second phase in the non-equilibrium phase diagram of Al-Mg alloys. Temperature T is chosen as this temperature point. C Select a temperature range within ±10℃ of the high melting point second phase precipitation start temperature in the non-equilibrium phase diagram of Al-Mg alloys; where the low melting point temperature range is 25~300℃, the intermediate melting point temperature range is 300~500℃, and the high melting point temperature range is 500~650℃.

[0034] According to the non-equilibrium phase diagram of Al-Mg alloys, the precipitation start temperature of the low-melting-point second phase is 240℃, therefore temperature T A Choose 240℃; the intermediate melting point and the temperature at which the second phase precipitation begins are 360℃, therefore temperature T B Choose 360℃; the precipitation start temperature of the high-melting-point second phase is 600℃, therefore temperature T C Select 590℃;

[0035] (3) The Al-Mg alloy was heated from room temperature to V a The temperature rises to point T at a rate of 600℃ / h. A (240℃), reaching temperature point T A (240℃) followed by Vb The temperature rises to point T at a rate of 30℃ / h. B (360℃), reaching temperature point T B (360℃) followed by V c The temperature rises at a rate of (℃ / h) to the temperature point T. C (590℃), reaching temperature point T C After reaching 590℃, air cooling is performed; in this embodiment...

[0036] The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in this embodiment is shown in the scanning electron microscope. Figure 4 ,from Figure 4 It can be seen that the sparingly soluble second phase partially re-dissolves and spheroidizes, and the coarse second phase decomposes into several small-sized phases.

[0037] Example 2: A rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys (see...) Figure 1 The specific steps are as follows:

[0038] (1) The Al-Mg aluminum alloy used in this embodiment is the same Al-Mg aluminum alloy as in Example 1. Therefore, the non-equilibrium phase diagram of the Al-Mg alloy calculated by the phase diagram calculation module is the same as that in Example 1.

[0039] (2) According to the non-equilibrium phase diagram of Al-Mg alloy, the precipitation start temperature of the low-melting-point second phase is 240℃, therefore the temperature point T A Choose 250℃; the intermediate melting point and the temperature at which the second phase precipitation begins are 360℃, therefore temperature T B Choose 360℃; the precipitation start temperature of the high-melting-point second phase is 600℃, therefore temperature T C Select 590℃;

[0040] (3) The Al-Mg alloy was heated from room temperature to V a The temperature rises to point T at a rate of 550℃ / h. A (250℃), reaching temperature point T A (250℃) then V b The temperature rises to point T at a rate of 22℃ / h. B (360℃), reaching temperature point T B (360℃) followed by V c The temperature rises to point T at a rate of 5℃ / h. C (590℃), reaching temperature point T C After reaching 590℃, air cooling is performed; in this embodiment...

[0041] The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in this embodiment is shown in the scanning electron microscope. Figure 5 ,from Figure 5 It can be seen that the sparingly soluble second phase partially re-dissolves and spheroidizes, and the coarse second phase decomposes into several small-sized phases.

[0042] Example 3: A rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys (see Example 4) Figure 1 The specific steps are as follows:

[0043] (1) The Al-Mg aluminum alloy used in this embodiment is the same Al-Mg aluminum alloy as in Example 1. Therefore, the non-equilibrium phase diagram of the Al-Mg alloy calculated by the phase diagram calculation module is the same as that in Example 1.

[0044] (2) According to the non-equilibrium phase diagram of Al-Mg alloy, the precipitation start temperature of the low-melting-point second phase is 240℃, therefore the temperature point T A Choose 260℃; the intermediate melting point and the temperature at which the second phase precipitation begins are 360℃, therefore temperature T B Choose 380℃; the precipitation start temperature of the high-melting-point second phase is 600℃, therefore temperature T C Select 598℃;

[0045] (3) The Al-Mg alloy was heated from room temperature to V a The temperature rises to point T at a rate of 600℃ / h. A (260℃), reaching temperature point T A (260℃) followed by V b The temperature rises to point T at a rate of 20℃ / h. B (380℃), reaching temperature point T B (380℃) followed by V c The temperature rises to point T at a rate of (4℃ / h). C (598℃), reaching temperature point T C (598℃) followed by air cooling; in this embodiment

[0046] The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in this embodiment is shown in the scanning electron microscope. Figure 6 ,from Figure 6 It can be seen that the sparingly soluble second phase partially re-dissolves and spheroidizes, and the coarse second phase decomposes into several small-sized phases.

[0047] Example 4: A rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys (see Example 4) Figure 1 The specific steps are as follows:

[0048] (1) The Al-Mg aluminum alloy used in this embodiment is the same Al-Mg aluminum alloy as in Example 1. Therefore, the non-equilibrium phase diagram of the Al-Mg alloy calculated by the phase diagram calculation module is the same as that in Example 1.

[0049] (2) According to the non-equilibrium phase diagram of Al-Mg alloy, the precipitation start temperature of the low-melting-point second phase is 240℃, therefore the temperature point T A Choose 260℃; the intermediate melting point and the temperature at which the second phase precipitation begins are 360℃, therefore temperature T B Choose 400℃; the precipitation start temperature of the high-melting-point second phase is 600℃, therefore temperature T C Select 596℃;

[0050] (3) The Al-Mg alloy was heated from room temperature to V a The temperature rises to point T at a rate of 594℃ / h. A (260℃), reaching temperature point T A (260℃) followed by V b The temperature rises to point T at a rate of 18℃ / h. B (400℃), reaching temperature point T B (400℃) then V c The temperature rises to point T at a rate of (4℃ / h). C (596℃), reaching temperature point T C After reaching 596℃, air cooling is performed; in this embodiment...

[0051] The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in this embodiment is shown in the scanning electron microscope. Figure 7 ,from Figure 7 It can be seen that the sparingly soluble second phase partially re-dissolves and spheroidizes, and the coarse second phase decomposes into several small-sized phases.

[0052] Example 5: A rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys (see Example 5) Figure 1 The specific steps are as follows:

[0053] (1) The Al-Mg aluminum alloy used in this embodiment is the same Al-Mg aluminum alloy as in Example 1. Therefore, the non-equilibrium phase diagram of the Al-Mg alloy calculated by the phase diagram calculation module is the same as that in Example 1.

[0054] (2) According to the non-equilibrium phase diagram of Al-Mg alloy, the precipitation start temperature of the low-melting-point second phase is 240℃, therefore the temperature point T A Choose 280℃; the intermediate melting point and the temperature at which the second phase precipitation begins are 360℃, therefore temperature T B Choose 400℃; the precipitation start temperature of the high-melting-point second phase is 600℃, therefore temperature T C Select 605℃;

[0055] (3) The Al-Mg alloy was heated from room temperature to V aThe temperature rises to point T at a rate of 595℃ / h. A (280℃), reaching temperature point T A (280℃) followed by V b The temperature rises to point T at a rate of 17℃ / h. B (400℃), reaching temperature point T B (400℃) then V c The temperature rises to point T at a rate of (4℃ / h). C (605℃), reaching temperature point T C (605℃) followed by air cooling; in this embodiment

[0056] The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in this embodiment is shown in the scanning electron microscope. Figure 8 ,from Figure 8 It can be seen that the sparingly soluble second phase partially re-dissolves and spheroidizes, and the coarse second phase decomposes into several small-sized phases.

[0057] Comparative Example 1: The Al-Mg aluminum alloy used in this comparative example is the same Al-Mg aluminum alloy as in Example 1;

[0058] An isothermal heat treatment method for Al-Mg aluminum alloys, the specific steps of which are as follows:

[0059] The as-cast Al-Mg alloy was held at 320℃ for 8 hours, then rapidly heated to 590℃ and held for 16 hours, followed by air cooling.

[0060] The tissue samples from this comparative example, treated with isothermal heat therapy, are shown in the scanning electron microscope. Figure 9 As can be seen from the figure, the insoluble second phase has little re-dissolution, the coarse second phase did not decompose, and overheating of the low-temperature eutectic structure occurred;

[0061] At least 10 scanning electron microscope images of the insoluble phase were selected from Comparative Example 1 and Examples 1-5 without difference. Statistical results are shown in the figure. Figure 3 ,from Figure 3 It can be seen that the volume fraction of the refractory phase after the isothermal homogenization heat treatment process in Comparative Example 1 is 4.68%, which is much higher than that in Examples 1 to 5, where the volume fraction of the refractory phase in Example 5 is only 2.21%. The volume fraction of the refractory phase in Al-Mg alloy is greatly reduced after discontinuous temperature gradient heat treatment, which is due to the fact that the discontinuous temperature gradient promotes the migration of atoms of difficult-to-diffuse elements.

[0062] Example 6: A rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys (see Example 6) Figure 1 The specific steps are as follows:

[0063] (1) The measured chemical composition of Al-Mg aluminum alloy was input into JMatPro software, and the non-equilibrium phase diagram of Al-Mg alloy was calculated using the phase diagram calculation module (see Figure 10 The measured chemical composition of Al-Mg aluminum alloy is shown in Table 2.

[0064] Table 2 Measured Chemical Composition of Al-Mg Aluminum Alloys

[0065]

[0066] (2) Determine the temperature point T based on the non-equilibrium phase diagram of Al-Mg alloy. A Temperature point T B and temperature point T C The temperature point T A The selected temperature is within the range of 0–50°C above the precipitation start temperature of the low-melting-point second phase in the non-equilibrium phase diagram of the Al-Mg alloy. Temperature T is defined as... B Select a temperature within the range of 0–50°C above the intermediate melting point and the precipitation start temperature of the second phase in the non-equilibrium phase diagram of Al-Mg alloys. Temperature T is chosen as this temperature point. C Select a temperature range within ±10℃ of the high melting point second phase precipitation start temperature in the non-equilibrium phase diagram of Al-Mg alloys; where the low melting point temperature range is 25~300℃, the intermediate melting point temperature range is 300~500℃, and the high melting point temperature range is 500~650℃.

[0067] According to the non-equilibrium phase diagram of Al-Mg alloys, the precipitation start temperature of the low-melting-point second phase is 200℃, therefore temperature T A Choose 230℃; the intermediate melting point and the temperature at which the second phase precipitation begins are 350℃, therefore temperature T B Choose 370℃; the precipitation start temperature of the high-melting-point second phase is 560℃, therefore temperature T C Select 575℃;

[0068] (3) The Al-Mg alloy was heated from room temperature to V a The temperature rises to point T at a rate of 600℃ / h. A (230℃), reaching temperature point T A (230℃) followed by V b The temperature rises to point T at a rate of 25℃ / h. B (370℃), reaching temperature point T B (370℃) followed by V c The temperature rises to point T at a rate of 5℃ / h. C (575℃), reaching temperature point T C (575℃) followed by air cooling; in this embodiment

[0069] The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in this embodiment is shown in the scanning electron microscope. Figure 11 ,from Figure 11 It can be seen that the sparingly soluble second phase partially re-dissolves and spheroidizes, and the coarse second phase decomposes into several small-sized phases;

[0070] In this embodiment, the volume fraction of the sparingly soluble phase is 2.37%.

[0071] Example 7: A rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys (see Example 7) Figure 1 The specific steps are as follows:

[0072] (1) The measured chemical composition of Al-Mg aluminum alloy was input into JMatPro software, and the non-equilibrium phase diagram of Al-Mg alloy was calculated using the phase diagram calculation module (see Figure 12 The measured chemical composition of Al-Mg aluminum alloy is shown in Table 3.

[0073] Table 3 Measured Chemical Composition of Al-Mg Aluminum Alloy

[0074]

[0075] (2) Determine the temperature point T based on the non-equilibrium phase diagram of Al-Mg alloy. A Temperature point T B and temperature point T C The temperature point T A The selected temperature is within the range of 0–50°C above the precipitation start temperature of the low-melting-point second phase in the non-equilibrium phase diagram of the Al-Mg alloy. Temperature T is defined as... B Select a temperature within the range of 0–50°C above the intermediate melting point and the precipitation start temperature of the second phase in the non-equilibrium phase diagram of Al-Mg alloys. Temperature T is chosen as this temperature point. C Select a temperature range within ±10℃ of the high melting point second phase precipitation start temperature in the non-equilibrium phase diagram of Al-Mg alloys; where the low melting point temperature range is 25~300℃, the intermediate melting point temperature range is 300~500℃, and the high melting point temperature range is 500~650℃.

[0076] According to the non-equilibrium phase diagram of Al-Mg alloys, the precipitation start temperature of the low-melting-point second phase is 250℃, therefore temperature T A Choose 270℃; the intermediate melting point and the temperature at which the second phase precipitation begins are 440℃, therefore temperature T B Choose 460℃; the precipitation start temperature of the high-melting-point second phase is 580℃, therefore temperature T C Choose 577℃;

[0077] (3) The Al-Mg alloy was heated from room temperature to V a The temperature rises to point T at a rate of 600℃ / h. A(270℃), reaching temperature point T A (270℃) followed by V b The temperature rises to point T at a rate of 15℃ / h. B (460℃), reaching temperature point T B (460℃) followed by V c The temperature rises to point T at a rate of 3℃ / h. C (577℃), reaching temperature point T C After reaching 577℃, air cooling is performed; in this embodiment...

[0078] The microstructure of the Al-Mg alloy subjected to discontinuous temperature gradient heat treatment in this embodiment is shown in the scanning electron microscope. Figure 13 ,from Figure 13 It can be seen that the sparingly soluble second phase partially re-dissolves and spheroidizes, and the coarse second phase decomposes into several small-sized phases; in this embodiment, the volume fraction of the sparingly soluble phase is 1.88%.

[0079] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A rapid heat treatment method for eliminating discontinuous temperature gradients in Al-Mg alloys to eliminate insoluble phases, characterized in that, The specific steps are as follows: Al-Mg alloys were heated from room temperature at V a The rate of increase rises to temperature point T A Reaching temperature point T A Later with V b The rate of increase rises to temperature point T B Reaching temperature point T B Later with V c The rate of increase rises to temperature point T C Reaching temperature point T C Then air cooling is performed; The , V a 500~600℃ / h, V b The temperature is 10~40℃ / h, V c The rate is 2~10℃ / h; The temperature point T A Temperature point T B and temperature point T C The method for determining it includes the following steps: (1) The measured chemical composition of Al-Mg aluminum alloy was input into JMatPro software, and the non-equilibrium phase diagram of Al-Mg alloy was calculated using the phase diagram calculation module; (2) Determine the temperature point T based on the non-equilibrium phase diagram of Al-Mg alloy. A Temperature point T B and temperature point T C The temperature point T A The selected temperature is within the range of 0–50°C above the precipitation initiation temperature of the low-melting-point second phase in the non-equilibrium phase diagram of the Al-Mg alloy. Temperature T is defined as... B Select a temperature within the range of 0–50°C above the intermediate melting point and the precipitation start temperature of the second phase in the non-equilibrium phase diagram of Al-Mg alloys. Temperature T is chosen as this temperature point. C Select a temperature range of ±10℃ from the precipitation start temperature of the high-melting-point second phase in the non-equilibrium phase diagram of Al-Mg alloys; The low melting point temperature range is 25~300℃, the intermediate melting point temperature range is 300~500℃, and the high melting point temperature range is 500~650℃.

2. The method for rapidly eliminating discontinuous temperature gradient heat treatment of sparingly soluble phases in Al-Mg alloys according to claim 1, characterized in that: V a 500~600℃ / h, V b The temperature is 10~30℃ / h, V c The temperature is 2~8℃ / h.

3. The method for rapidly eliminating discontinuous temperature gradient heat treatment of refractory phases in Al-Mg alloys according to claim 2, characterized in that: V a The temperature is 550~600℃ / h, V b The temperature is 15~25℃ / h, V c The temperature is 3~6℃ / h.

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