A method to accelerate the creep forming of magnesium alloys

Abstract

This invention provides a method for accelerating the creep forming of magnesium alloys, comprising the following steps: providing a magnesium alloy billet; pre-deforming the magnesium alloy billet at room temperature to introduce twins into the grains of the magnesium alloy, obtaining a twinned magnesium alloy billet; and creep forming the twinned magnesium alloy billet under creep forming temperature and stress; wherein the volume fraction of the twins after the pre-deformation treatment is ≥10%. This method is simple, highly controllable, and achieves a dual improvement in forming efficiency and product quality, making it suitable for large-scale industrial production and possessing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of metal material processing technology, and in particular relates to a method for accelerating the creep forming of magnesium alloys. Background Technology

[0002] Magnesium alloys, due to their advantages such as low density, high specific strength, and high specific stiffness, are widely used in aerospace structural components, automotive manufacturing, and electronic communications, and are one of the core materials for lightweight manufacturing of high-end equipment, with broad application prospects. However, magnesium alloys have a hexagonal close-packed (HCP) crystal structure, and the number of slip systems that can be activated at room temperature is limited, resulting in poor plastic forming ability. Creep forming, as a low-temperature slow plastic forming technology, can achieve slow and precise forming of thin-walled magnesium alloy plates under certain temperature and constant stress conditions, effectively avoiding the defect of poor room temperature plasticity of magnesium alloys, and is one of the core processes for precision machining of complex magnesium alloy components. However, the traditional magnesium alloy creep forming process relies on the slow dislocation slip and diffusion deformation of the material to achieve plastic forming. The steady-state creep rate is low, and the holding and pressure holding time for a single forming is as long as tens of hours. The overall forming cycle is long and the production efficiency is extremely low, which greatly increases the manufacturing cost of magnesium alloy components and seriously limits the large-scale and industrial application of magnesium alloy creep forming technology.

[0003] Existing technologies primarily focus on optimizing creep temperature, stress parameters, alloy composition modification, or heat treatment processes. The core approach is to adapt the overall material properties to the creep process, but this cannot fundamentally overcome the bottleneck of low creep rates. Therefore, this invention provides a method to accelerate the creep forming of magnesium alloys, solving the problems of long forming cycles and low production efficiency in existing magnesium alloy creep forming methods. Summary of the Invention

[0004] The main objective of this invention is to provide a method for accelerating the creep forming of magnesium alloys, aiming to solve the technical problems of long creep forming cycles and low production efficiency in existing magnesium alloys.

[0005] To achieve the above objectives, the present invention provides a method for accelerating the creep forming of magnesium alloys, comprising the following steps: S1: Provide magnesium alloy billets.

[0006] S2: At 10~35℃, the magnesium alloy billet is pre-deformed to introduce twins into the grains of the magnesium alloy, thereby obtaining a magnesium alloy billet containing twins.

[0007] S3: The twinned magnesium alloy billet is subjected to creep forming at creep forming temperature and stress.

[0008] The volume fraction of the twins after the pre-deformation treatment is ≥10%.

[0009] According to an embodiment of this application, the magnesium alloy billet is pre-deformed at room temperature.

[0010] The strain of the pre-deformation is 2-15%.

[0011] The strain rate of the pre-deformation is 10. -4 s -1 ~10 2 s -1 .

[0012] According to an embodiment of this application, the creep forming temperature is 50~250 °C.

[0013] The stress causing the creep deformation is a constant stress.

[0014] The creep stress is 20~250 MPa.

[0015] According to an embodiment of this application, the pretreatment method includes heating.

[0016] The heating temperature is 300~450 ℃.

[0017] The heating time is 0.5 to 24 hours.

[0018] According to the embodiments of this application, the creep forming time is 0.5 to 8 hours.

[0019] According to an embodiment of this application, the twin crystal is structured as a lenticular twin wafer layer.

[0020] The twin includes one or more of the following: tensile twin, compressive twin, and secondary twin.

[0021] According to embodiments of this application, the magnesium alloy includes one of pure magnesium, AZ31, AZ42, AM60, ZK21, and MB1 non-precipitated magnesium alloys.

[0022] Alternatively, the magnesium alloy may include one of pure magnesium, AZ31, AZ42, AM60, ZK21, or MB1 weak precipitation-strengthened magnesium alloy.

[0023] According to embodiments of this application, the pre-deformation process includes single-pass rolling deformation or multi-pass rolling deformation.

[0024] According to embodiments of this application, the pre-deformation process includes one or more of stretching, compression, rolling, bending, and high-speed impact.

[0025] According to embodiments of this application, the magnesium alloy billet is formed by at least one of die casting, extrusion, and rolling.

[0026] The rolling forming process includes single-pass rolling along the extrusion direction of the magnesium alloy billet.

[0027] The reduction in a single rolling pass is 3-8%.

[0028] The magnesium alloy billet includes flat plate magnesium alloy billet or ribbed plate magnesium alloy billet.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: The aforementioned method for accelerating the creep forming of magnesium alloys, by pre-deforming the magnesium alloy billet before creep forming, introduces twin boundaries that provide numerous high-energy regions, promoting dislocation movement and actively introducing twins with a volume fraction ≥10% into the grains. Utilizing the regulatory effect of twin boundaries on grain boundary slip and dislocation movement, the creep rate of the magnesium alloy is significantly accelerated, and the creep forming cycle is drastically shortened. This effectively solves the technical problems of long creep forming cycles and low production efficiency in existing technologies, providing a new technical approach for achieving efficient and mass-produced creep forming of magnesium alloy components. Furthermore, by precisely controlling the pre-deformation process parameters (such as deformation amount and deformation rate), this invention can quantitatively control the twin integral number, thereby effectively intervening in the subsequent creep forming kinetics, avoiding defects such as microcracks and grain distortion caused by excessive deformation. The formed magnesium alloy components exhibit high dimensional accuracy, uniform microstructure, and good performance consistency, increasing the strain rate in the creep steady-state stage and significantly shortening the total forming time.

[0030] The method of this invention is simple and highly controllable, requiring no additional alloying elements or complex heat treatment processes. The pre-deformation step can be completed using conventional rolling mills or presses without the need for specialized equipment, making it easy to integrate with existing creep forming production lines. Furthermore, the introduction of twinned structures helps to refine the deformation structure and homogenize the stress distribution, which is beneficial for obtaining creep-formed components with uniform structure and stable performance. This approach achieves a dual improvement in forming efficiency and product quality, making it suitable for large-scale industrial mass production and possessing broad application prospects. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0032] Figure 1 The relationship between creep strain and time is shown for AZ42 magnesium alloy in Example 1 under different pre-deformation strains, after creep test at creep forming temperature of 150 ℃ and constant stress of 40 MPa. Figure 2 The relationship between creep strain and time is shown for AZ42 magnesium alloy in Example 1 under different pre-deformation strains, after creep test at creep forming temperature of 150 ℃ and constant stress of 70 MPa. Figure 3 The relationship between creep strain and time is shown for AZ42 magnesium alloy in Example 1 under different pre-deformation strains, after creep test at creep forming temperature of 150 ℃ and constant stress of 100 MPa. Figure 4 This is the relationship between creep strain and time after creep tests were conducted on AZ31 magnesium alloy in Example 2 under different pre-deformation methods at a creep forming temperature of 150 ℃ and a constant stress of 40 MPa. Figure 5 This is the relationship between creep strain and time after creep tests were conducted on AZ31 magnesium alloy in Example 2 under different pre-deformation methods at a creep forming temperature of 150 ℃ and a constant stress of 70 MPa. Figure 6 This is the relationship between creep strain and time after creep tests were conducted on AZ31 magnesium alloy in Example 2 under different pre-deformation methods at a creep forming temperature of 150 ℃ and a constant stress of 100 MPa. Figure 7 The image shows the twinned structure inside the AZ42 magnesium alloy after pre-stretching by 5% in Example 1; where (a) is a grain orientation diagram and (b) is a twin distribution diagram.

[0033] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0036] To achieve the above objectives, the present invention provides a method for accelerating the creep forming of magnesium alloys, comprising the following steps: S1: Provide magnesium alloy billets.

[0037] In some embodiments, the magnesium alloy is pretreated to obtain a clean and uniform magnesium alloy billet.

[0038] In some embodiments, a magnesium alloy plate to be formed is selected as a magnesium alloy billet. The plate can be formed by die casting, extrusion or rolling. The plate type is a flat plate or a ribbed plate.

[0039] In some embodiments, AZ42 magnesium alloy or AZ31 magnesium alloy extruded sheet is provided with an initial thickness of 1~3 mm and an average grain size of 20~30 μm; the extruded sheet is placed in a heat treatment furnace at 380~420℃ for 1~2 h, then removed and naturally cooled in air to remove oxide scale and oil stains from the surface of the sheet, thereby obtaining a clean and uniform magnesium alloy billet.

[0040] S2: At 10~35℃, preferably at room temperature, the magnesium alloy billet is pre-deformed to introduce twins into the grains of the magnesium alloy, thereby obtaining a magnesium alloy billet containing twins.

[0041] The volume fraction of the twins after the pre-deformation treatment is ≥10%.

[0042] In some embodiments, pre-deformation is performed using single-pass or multi-pass rolling deformation to introduce more twins within the grains of the magnesium alloy. After pre-deformation, the volume fraction of twins is ≥10%.

[0043] In some embodiments, the presence of twins is determined based on metallographic or crystal orientation diagrams (EBSD), and the area fraction or proportion of twin boundaries of twins is calculated and used as the volume fraction of twins.

[0044] In some embodiments, the volume fraction of the twins after the pre-deformation treatment is 10-30%.

[0045] In some embodiments, the volume fraction of the twins after the pre-deformation treatment is 10-25%.

[0046] In some embodiments, the volume fraction of the twins after the pre-deformation treatment is 10-20%.

[0047] In some embodiments, the volume fraction of the twins after the pre-deformation treatment is 12-19%.

[0048] S3: The twinned magnesium alloy billet is subjected to creep forming at creep forming temperature and stress.

[0049] In some embodiments, the twinned magnesium alloy billet is placed in a creep forming mold and creep forming is performed at a forming temperature of 50 ℃ to 250 ℃ and a constant stress of 20 MPa to 250 MPa for a holding time of 0.5 h to 8 h. During this process, the twins introduced by pre-deformation act as rapid diffusion channels, accelerating dislocation slip during creep and thus significantly increasing the creep rate.

[0050] The aforementioned method for accelerating the creep forming of magnesium alloys, by pre-deforming the magnesium alloy billet before creep forming, introduces twin boundaries that provide numerous high-energy regions, promoting dislocation movement and actively introducing twins with a volume fraction ≥10% into the grains. Utilizing the regulatory effect of twin boundaries on grain boundary slip and dislocation movement, the creep rate of the magnesium alloy is significantly accelerated, and the creep forming cycle is drastically shortened. This effectively solves the technical problems of long creep forming cycles and low production efficiency in existing technologies, providing a new technical approach for achieving efficient and mass-produced creep forming of magnesium alloy components. Furthermore, by precisely controlling the pre-deformation process parameters (such as deformation amount and deformation rate), this invention can quantitatively control the twin integral number, thereby effectively intervening in the subsequent creep forming kinetics, avoiding defects such as microcracks and grain distortion caused by excessive deformation. The formed magnesium alloy components exhibit high dimensional accuracy, uniform microstructure, and good performance consistency, increasing the strain rate in the creep steady-state stage and significantly shortening the total forming time.

[0051] In some embodiments, the strain of the pre-deformation is 2-15%.

[0052] The strain rate of the pre-deformation is 10. -4 s -1 ~10 2 s -1 .

[0053] In some embodiments, the strain of the pre-deformation is 5-10%.

[0054] In some embodiments, the strain of the pre-deformation is 2-8%. Adjusting the strain appropriately can result in a high twin density without inducing significant cracking.

[0055] In some embodiments, the strain rate of the pre-deformation is 10. -3 s -1 ~10 2 s -1 .

[0056] In some embodiments, the strain rate of the pre-deformation is 10. -3 s -1 ~10 -2 s -1 .

[0057] In some embodiments, the creep forming temperature is 50~250 °C.

[0058] The stress causing the creep deformation is a constant stress.

[0059] The creep stress is 20~250 MPa.

[0060] In some embodiments, the creep forming temperature is 150~250 °C.

[0061] The creep stress is 30~150 MPa.

[0062] In some embodiments, the creep forming temperature is 150~200 °C.

[0063] The creep stress is 40~120 MPa.

[0064] In some embodiments, the creep forming temperature is 140~160 °C.

[0065] The creep stress is 40~100 MPa.

[0066] In some embodiments, the pretreatment method includes heating.

[0067] The heating temperature is 300~450 ℃.

[0068] The heating time is 0.5 to 24 hours.

[0069] In some embodiments, the creep deformation duration is 0.5 to 8 hours.

[0070] In some embodiments, the creep forming time is 0.5 to 6 hours.

[0071] In some embodiments, the creep forming time is 1 to 5 hours.

[0072] In some embodiments, the twin's structure is a lenticular twin wafer layer.

[0073] The twin includes one or more of the following: tensile twin, compressive twin, and secondary twin.

[0074] In some embodiments, the magnesium alloy includes one of pure magnesium, AZ31, AZ42, AM60, ZK21, and MB1 non-precipitated magnesium alloys.

[0075] In some embodiments, the magnesium alloy includes one of pure magnesium, AZ31, AZ42, AM60, ZK21, and MB1 weak precipitation-strengthened magnesium alloy.

[0076] In some embodiments, the present invention requires the selection of suitable magnesium alloys that do not produce significant age-induced precipitation strengthening at creep temperatures, thereby highlighting the accelerating effect of pre-deformed twins on the creep rate.

[0077] In some embodiments, the pre-deformation process includes single-pass rolling deformation or multi-pass rolling deformation.

[0078] In some embodiments, the pre-deformation process includes one or more of stretching, compression, rolling, bending, and high-speed impact.

[0079] The rolling forming process includes single-pass rolling along the extrusion direction of the magnesium alloy billet.

[0080] The reduction in a single rolling pass is 3-8%.

[0081] The magnesium alloy billet includes flat plate magnesium alloy billet or ribbed plate magnesium alloy billet.

[0082] In some embodiments, the reduction in a single rolling pass is 4-6%.

[0083] In some embodiments, the rolling forming includes unidirectional rolling along the extrusion direction of the magnesium alloy billet, with a single pass reduction of 4-6%, for a total of two passes.

[0084] In some embodiments, the rolling forming includes cross rolling, in which the sheet is rotated horizontally by 90° after one rolling pass is completed, and then the next rolling pass is performed. The reduction amount of each cross rolling pass is 4~6%, and a total of two rolling passes are performed.

[0085] In some embodiments, the pre-deformation process includes one of stretching, compression, rolling, bending, and high-speed impact.

[0086] In some embodiments, the magnesium alloy billet is formed by at least one of die casting, extrusion, and rolling.

[0087] The method of this invention is simple and highly controllable, requiring no additional alloying elements or complex heat treatment processes. The pre-deformation step can be completed using conventional rolling mills or presses without the need for specialized equipment, making it easy to integrate with existing creep forming production lines. Furthermore, the introduction of twinned structures helps to refine the deformation structure and homogenize the stress distribution, which is beneficial for obtaining creep-formed components with uniform structure and stable performance. This approach achieves a dual improvement in forming efficiency and product quality, making it suitable for large-scale industrial mass production and possessing broad application prospects.

[0088] To further illustrate the present invention, the following examples are provided: Example 1 A method for accelerating the creep forming of magnesium alloys, comprising the following steps: S1: Provide AZ42 magnesium alloy extruded sheet with an initial thickness of 2 mm and an average grain size of 25 μm; place the AZ42 magnesium alloy extruded sheet in a 410℃ heat treatment furnace for 2 h, then take it out and let it cool naturally in the air to remove the oxide scale and oil stains on the surface of the sheet, and obtain a clean and uniform blank to be deformed.

[0089] S2: At room temperature, a single-pass stretching (pre-deformation treatment) is performed along the extrusion direction of the billet to be deformed, with a strain rate of 10. -3 s -1 After pre-deformation, a twinned AZ42 magnesium alloy sheet was obtained. Testing revealed that the internal twin volume fraction of the AZ42 magnesium alloy sheet was 19%, with no microcracks or deformation defects. The twin structure consisted of lenticular twin lamellae; the twins were tensile twins, compressive twins, and secondary twins.

[0090] S3: The twinned AZ42 magnesium alloy plate was placed into the creep test mold and creeped under creep forming temperature and stress. The creep forming temperature was 150 ℃ and the creep forming stress was a constant stress of 40 MPa. The creep forming was completed after holding the temperature and pressure for 6 h.

[0091] To investigate the relationship between creep strain and time in AZ42 magnesium alloy under different pre-deformation strains, three sets of experiments were designed.

[0092] Experimental Group 1: As a control group, pure AZ42 magnesium alloy samples without pre-deformation treatment.

[0093] Experimental group 2: The strain of the pre-deformation was set at 2%.

[0094] Experimental group 3: The strain of the pre-deformation was set at 5%.

[0095] It should be noted that the pre-deformed strain is simply referred to as pre-tension, while the creep strain is... Figures 1-6 In Chinese, this is simply referred to as strain.

[0096] The specimens obtained from the above three sets of tests were subjected to creep tests at a creep forming temperature of 150 ℃ and a constant stress of 40 MPa.

[0097] See test results Figure 1 It can be seen that: within 10 hours, the maximum creep strain of the AZ42 magnesium alloy sheet sample in test group 2 that completed creep deformation was 0.46%; the maximum creep strain of the AZ42 magnesium alloy sheet sample in test group 3 that completed creep deformation was 0.77%. Figure 7 The right side of Figure (b) shows the legend: the red, green, and blue lines represent tensile twin boundaries, compressive twin boundaries, and secondary twin boundaries, respectively. See Figure (b). Figure 7It can be seen that the twinning structure inside the AZ42 magnesium alloy in Experiment Group 3 after pre-stretching by 5% consists of a large number of lenticular twin lamellae, with the proportions of tensile twins, compressive twins and secondary twins being 8.4%, 6.9% and 3.7%, respectively; while under the same experimental conditions, the maximum creep strain of the AZ42 magnesium alloy plate sample in Experiment Group 1 that has completed creep deformation is only 0.29%.

[0098] The specimens obtained from the above three sets of tests were subjected to creep tests at a creep forming temperature of 150 ℃ and a constant stress of 70 MPa.

[0099] See test results Figure 2 It can be seen that within 10 hours, the maximum creep strain of the AZ42 magnesium alloy plate sample in test group 1 that completed creep deformation was only 0.83%; while under the same creep temperature and creep stress, test group 3 only needed 1.5 hours to complete the same creep strain, which greatly shortened the creep deformation time.

[0100] The specimens obtained from the above three sets of tests were subjected to creep tests at a creep forming temperature of 150 ℃ and a constant stress of 100 MPa.

[0101] See test results Figure 3 It can be seen that when the creep strain reaches 2%, the time required for experimental groups 1, 2 and 3 is 6.9 h, 4.4 h and 1.3 h respectively, that is, pre-deformation significantly shortens the time required for creep deformation.

[0102] Example 2 Preferred method: A method for accelerating the creep forming of magnesium alloys, comprising the following steps: S1: Provide AZ31 magnesium alloy extruded sheet with an initial thickness of 2 mm and an average grain size of 25 μm; place the AZ31 magnesium alloy extruded sheet in a 400℃ heat treatment furnace for 2 h, then remove it and allow it to cool naturally in air to remove oxide scale and oil stains from the sheet surface, obtaining a clean and uniform blank to be deformed.

[0103] S2: At room temperature, single-pass rolling (pre-deformation treatment) is performed along the extrusion direction of the billet to be deformed, with a strain rate of 10. -3 s -1 After pre-deformation, a twinned AZ31 magnesium alloy sheet was obtained. Testing revealed that the internal twin volume fraction of the AZ31 magnesium alloy sheet was 12%, with no microcracks or deformation defects. The twin structure consisted of lenticular twinned lamellae; the twins were tensile twins, compressive twins, and secondary twins.

[0104] S3: The twinned AZ31 magnesium alloy plate was placed into a creep test mold and creeped under creep forming temperature and stress. The creep forming temperature was 150 ℃. The creep forming stress was a constant stress of 70 MPa. The creep forming time required to reach 0.8% creep strain was 3.5 h.

[0105] To investigate the relationship between creep strain and time in AZ31 magnesium alloy under different pre-deformation methods, three sets of experiments were designed.

[0106] Test Group 4: As a control group, compared with the above preferred method, a pure AZ31 magnesium alloy sample without pre-deformation treatment was used, and the other steps were the same as the preferred method in Example 2.

[0107] Experimental Group 5: The pre-deformation method was set as unidirectional rolling, which is the same as the preferred method in Example 2.

[0108] Experimental Group 6: Compared with Experimental Group 5, the pre-deformation method was changed; that is, Experimental Group 6 set the pre-deformation method to cross rolling.

[0109] It should be noted that in unidirectional rolling, the reduction per pass is 5%, and a total of two passes are rolled; in cross rolling, after the sheet is rolled once, the sheet is rotated horizontally by 90° and then the next pass is rolled. The reduction per pass in cross rolling is 5%, and a total of two passes are rolled.

[0110] The specimens obtained from the above three sets of tests were subjected to creep tests at a creep forming temperature of 150 ℃ and a constant stress of 40 MPa.

[0111] See test results Figure 4 It can be seen that within 10 hours, the maximum creep strain of the AZ31 magnesium alloy sheet sample that completed creep deformation in test group 5 was 0.67%; the maximum creep strain of the AZ31 magnesium alloy sheet sample that completed creep deformation in test group 6 was 0.67%; while under the same test conditions, the maximum creep strain of the AZ31 magnesium alloy sheet sample that completed creep deformation in test group 4 was only 0.29%.

[0112] The specimens obtained from the above three sets of tests were subjected to creep tests at 150 °C and constant stress of 70 MPa.

[0113] See test results Figure 5It can be seen that within 10 hours, the maximum creep strain of the AZ31 magnesium alloy sheet sample that completed creep deformation in test group 5 was 1.28%; the maximum creep strain of the AZ31 magnesium alloy sheet sample that completed creep deformation in test group 6 was 1.78%; while under the same test conditions, the maximum creep strain of the AZ31 magnesium alloy sheet sample that completed creep deformation in test group 4 was only 0.83%.

[0114] The specimens obtained from the above three sets of tests were subjected to creep tests at 150 °C and a constant stress of 100 MPa.

[0115] See test results Figure 6 It can be seen that within 10 hours, the maximum creep strain of the AZ31 magnesium alloy sheet sample that completed creep deformation in test group 5 was 11.8%; the maximum creep strain of the AZ31 magnesium alloy sheet sample that completed creep deformation in test group 6 was 15.6%; while under the same test conditions, the maximum creep strain of the AZ31 magnesium alloy sheet sample that completed creep deformation in test group 4 was only 2.4%.

[0116] The aforementioned method for accelerating the creep forming of magnesium alloys, by pre-deforming the magnesium alloy billet before creep forming, introduces twin boundaries that provide numerous high-energy regions, promoting dislocation movement and actively introducing twin structures with a volume fraction ≥10% within the grains. Utilizing the hindering and regulating effect of twin boundaries on grain boundary slip and dislocation movement, the creep rate of the magnesium alloy is significantly accelerated, and the creep forming cycle is drastically shortened. This effectively solves the technical problems of long creep forming cycles and low production efficiency in existing technologies, providing a new technical approach for achieving efficient and mass-produced creep forming of magnesium alloy components. Furthermore, by precisely controlling the pre-deformation process parameters (such as deformation amount and deformation rate), this invention can quantitatively control the volume fraction of twins, thereby effectively intervening in the subsequent creep forming kinetics, avoiding defects such as microcracks and grain distortion caused by excessive deformation. The formed magnesium alloy components exhibit high dimensional accuracy, uniform microstructure, and good performance consistency, increasing the strain rate in the creep steady-state stage by 50%~400% and significantly shortening the total forming time.

[0117] The method of this invention is simple and highly controllable, requiring no additional alloying elements or complex heat treatment processes. The pre-deformation step can be completed using conventional rolling mills or presses without the need for specialized equipment, making it easy to integrate with existing creep forming production lines. Furthermore, the introduction of twinned structures helps to refine the deformation structure and homogenize the stress distribution, which is beneficial for obtaining creep-formed components with uniform structure and stable performance. This approach achieves a dual improvement in forming efficiency and product quality, making it suitable for large-scale industrial mass production and possessing broad application prospects.

[0118] In summary, the above-described technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for accelerating the creep forming of magnesium alloys, characterized in that the steps include... include: S1: Provide magnesium alloy billets; S2: At 10~35℃, the magnesium alloy billet is pre-deformed to introduce twins into the grains of the magnesium alloy, thereby obtaining a magnesium alloy billet containing twins. S3: The twinned magnesium alloy billet is subjected to creep forming at creep forming temperature and stress; The volume fraction of the twins after the pre-deformation treatment is ≥10%.

2. The method for accelerating the creep forming of magnesium alloys according to claim 1, characterized in that, The magnesium alloy billet is pre-deformed at room temperature; The strain of the pre-deformation is 2-15%; The strain rate of the pre-deformation is 10. -4 s -1 ~10 2 s -1 .

3. The method for accelerating the creep forming of magnesium alloys according to claim 1, characterized in that, The creep forming temperature is 50~250 ℃; The stress causing the creep deformation is a constant stress; The creep stress is 20~250 MPa.

4. The method for accelerating the creep forming of magnesium alloys according to claim 1, characterized in that, The pretreatment method includes heating; The heating temperature is 300~450 ℃; The heating time is 0.5 to 24 hours.

5. The method for accelerating the creep forming of magnesium alloys according to claim 1, characterized in that, The creep deformation time is 0.5 to 8 hours.

6. The method for accelerating the creep forming of magnesium alloys according to claim 1, characterized in that, The twin crystal has a lenticular twin sheet structure; The twin includes one or more of the following: tensile twin, compressive twin, and secondary twin.

7. The method for accelerating the creep forming of magnesium alloys according to claim 1, characterized in that, The magnesium alloy includes one of pure magnesium, AZ31, AZ42, AM60, ZK21, and MB1 non-precipitated magnesium alloys; Alternatively, the magnesium alloy may include one of pure magnesium, AZ31, AZ42, AM60, ZK21, or MB1 weak precipitation-strengthened magnesium alloy.

8. The method for accelerating the creep forming of magnesium alloys according to claim 1, characterized in that, The pre-deformation process includes single-pass rolling deformation or multi-pass rolling deformation.

9. The method for accelerating the creep forming of magnesium alloys according to claim 1, characterized in that, The pre-deformation process includes one or more of the following: stretching, compression, rolling, bending, and high-speed impact.

10. The method for accelerating the creep forming of magnesium alloys according to claim 1, characterized in that, The magnesium alloy billet is formed by at least one of die casting, extrusion, and rolling. The rolling forming process includes single-pass rolling along the extrusion direction of the magnesium alloy billet; The reduction in a single rolling pass is 3-8%; The magnesium alloy billet includes flat plate magnesium alloy billet or ribbed plate magnesium alloy billet.

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