A thin-walled member having a gradient structure and properties and a forming method thereof

Abstract

The application provides a thin-walled component with gradient organization and performance and a forming method thereof, and belongs to the technical field of metal plastic forming. The forming method comprises the following steps: obtaining the size and shape of a blank material; obtaining the deformation priority of different regions in the thin-walled component after forming; obtaining the corresponding positions of the deformation weak region, the intermediate region and the deformation strong region in the blank material; obtaining the corresponding stress values of the different regions in the deformation process, determining the grain size of the different regions in the blank material, and obtaining a blank material design drawing; performing plastic processing on the homogeneous slab to obtain a gradient organization material; performing forming on the gradient organization material under ultra-low temperature environmental conditions to obtain a formed gradient organization material; and performing heat treatment modification to obtain the thin-walled component with gradient organization and performance. The application can obtain the thin-walled component with gradient organization and performance by actively regulating the gradient organization and controlling the forming process, and meets the service performance requirements of different positions.

Description

Technical Field

[0001] This invention relates to the field of metal plastic forming technology, and more specifically, to a thin-walled component with gradient structure and properties and its forming method. Background Technology

[0002] With the increasing trend towards more complex, lightweight, and integrated structures in fields such as aerospace, rail transportation, and energy and chemical engineering, the demand for complex thin-walled components with gradient microstructures and properties is becoming increasingly urgent. In existing technologies, the use of uniformly microstructured blanks during the forming process of thin-walled components with gradient microstructures and properties easily induces defects such as cracking and thickness reduction in areas subjected to significant plastic deformation, resulting in severely uneven wall thickness distribution. Under the same external load conditions, the load-bearing capacity of the thinned-walled region is lower, leading to uneven mechanical properties and significantly impacting the service performance of thin-walled components.

[0003] Furthermore, in aerospace and other complex components, the load conditions and mechanical performance requirements vary significantly across different parts during service. During the design process, designers aim for high load-bearing capacity in high-stress areas while maximizing material performance and minimizing weight loss in low-stress areas. For example, the thin-walled bottom of a large rocket fuel tank is a hemispherical curved component. During service, the central area of ​​this bottom component is subjected to internal fuel pressure. Simultaneously, as the primary location for transmitting engine loads, the central area experiences the most complex stress and is considered the "weakest point" in the bottom component. Typically, to meet service performance requirements, designers resort to localized welding reinforcement in this area, significantly increasing the weight of the bottom structure and reducing the rocket's effective payload capacity. Therefore, aerospace and other fields urgently require integrated, complex thin-walled components with gradient structure and performance.

[0004] Existing forming technologies, such as room temperature deep drawing, hot deep drawing, superplastic forming, or hot spinning, are all difficult to form complex thin-walled components with gradient structures and properties. In room temperature deep drawing, the gradient structure has a low forming limit, easily inducing stress concentration and uneven deformation, leading to cracking defects. In hot forming processes such as hot deep drawing, superplastic forming, and hot spinning, the gradient structure has poor thermal stability, easily exhibiting abnormal growth and softening, resulting in severe deterioration of the microstructure and localized thinning. Summary of the Invention

[0005] The problem addressed by this invention is how to provide a thin-walled component with gradient structure and properties and its forming method, which can actively control the structure and properties of different regions of the thin-walled component, reduce defects after forming, and improve service performance.

[0006] To address at least one of the aforementioned problems, the present invention provides a method for forming a thin-walled component with gradient structure and properties, comprising the following steps:

[0007] Step S1: Obtain the dimensions and shape of the blank material based on the three-dimensional model of the formed thin-walled component;

[0008] Step S2: Obtain the deformation priority of different regions in the formed thin-walled component, and divide the different regions of the formed thin-walled component into weak deformation region, intermediate region and strong deformation region.

[0009] Step S3: Based on the deformation priority of different regions in the formed thin-walled component, and the size and shape of the blank material, obtain the corresponding positions of the weak deformation region, the intermediate region and the strong deformation region in the blank material;

[0010] Step S4: Obtain the first stress value, second stress value, and third stress value of the weak deformation region, the intermediate region, and the strong deformation region during the deformation process. Based on the first stress value, the second stress value, and the third stress value, determine the grain size of different regions in the blank material to obtain a blank material design drawing with a gradient structure.

[0011] Step S5: Plastic process the homogeneous slab according to the blank material design drawing to obtain a gradient structure material with fine local grains, wherein the blank material is made of aluminum, aluminum alloy or stainless steel.

[0012] Step S6: The gradient structure material is shaped under ultra-low temperature conditions to obtain the shaped gradient structure material;

[0013] Step S7: The formed gradient structure material is heat-treated to modify it, thereby obtaining a thin-walled component with gradient structure and properties.

[0014] Preferably, step S1 includes:

[0015] The three-dimensional model of the formed thin-walled component is unfolded according to the law of constant volume to obtain the size and shape of the blank material.

[0016] Preferably, step S2 includes:

[0017] Based on material flow criteria and finite element simulation, the deformation priority of different regions in the formed thin-walled component is obtained. Regions that are prone to plastic deformation during the forming process are designated as weak deformation regions, regions that are not prone to plastic deformation during the forming process are designated as strong deformation regions, and regions in the formed thin-walled component other than the weak deformation regions and the strong deformation regions are designated as intermediate regions.

[0018] Preferably, step S3 includes:

[0019] Based on the deformation priority of different regions in the formed thin-walled component, and the size and shape of the blank material, reverse processing is performed using finite element simulation to obtain the corresponding positions of the weak deformation region, the intermediate region, and the strong deformation region in the blank material.

[0020] Preferably, step S4 includes:

[0021] The first stress value, the second stress value, and the third stress value of the weak deformation region, the intermediate region, and the strong deformation region during the deformation process are obtained;

[0022] The grain size in different regions of the blank material is determined according to Formula 1, which includes:

[0023] d Ⅰ -1 / 2 :d Ⅱ -1 / 2 :d Ⅲ -1 / 2 =σ Ⅰ -σ0:σ Ⅱ -σ0:σ Ⅲ -σ0;

[0024] In the formula, d Ⅰ d Ⅱ d Ⅲ σ represents the required grain size for the weak deformation region, the intermediate region, and the strong deformation region, respectively. Ⅰ σ Ⅱ σ Ⅲ These represent the first stress value, the second stress value, and the third stress value, respectively, and σ0 represents the material constant of the blank material;

[0025] Based on the grain size of different regions in the blank material, a design drawing of the blank material with a gradient structure is obtained.

[0026] Preferably, step S5 includes:

[0027] According to the design drawing of the blank material, the weak deformation zone and the intermediate region in the homogeneous slab are subjected to severe plastic deformation processing to obtain the gradient structure material with locally fine grain size.

[0028] Preferably, step S6 includes:

[0029] The gradient structure material is turned to obtain a gradient structure material blank with a uniform thickness in the length direction. The areas corresponding to the weak deformation area and the middle area in the gradient structure material blank are placed in an ultra-low temperature environment for cooling and forming at the same time to obtain the formed gradient structure material.

[0030] Preferably, step S7 includes:

[0031] The formed gradient structure material is subjected to solution treatment and aging treatment to obtain a thin-walled component with gradient structure and properties.

[0032] Preferably, after step S5 and before step S6, the method further includes:

[0033] The gradient structure material is annealed to obtain an annealed gradient structure material;

[0034] Step S6 includes:

[0035] The annealed gradient microstructure material is turned and then formed under ultra-low temperature conditions to obtain the formed gradient microstructure material.

[0036] This invention reverse-engineers the dimensions and structure of the blank material used to prepare the thin-walled component by performing reverse analysis on the formed thin-walled component. Then, based on the deformation priority of the thin-walled component during the forming process and practical application, it divides the component into regions such as weak deformation zone, intermediate zone, and strong deformation zone, and maps these regions to the blank material. The stress values ​​of different regions determine the grain size of different regions, thus obtaining a blank material design drawing to guide the processing of the blank material. In this process, the blank material can be reverse-engineered according to the forming process and application scenario of the thin-walled component, proactively designing the blank material according to the required performance of the thin-walled component to ensure that the performance meets the requirements. Based on the blank material design drawing, the homogeneous slab is plastically processed to give different grain sizes in different regions, and then formed in an ultra-low temperature environment, significantly enhancing its strength and work hardening ability, providing sufficient deformation capacity, and effectively suppressing defects such as structural damage. Finally, heat treatment modification is used to adjust the properties, resulting in a thin-walled component with gradient microstructure and properties. The forming method for thin-walled components with gradient structure and properties provided by the present invention can obtain a blank material design drawing through reverse design, adjust the gradient structure and properties of different regions of the blank material based on the blank material design drawing, and improve the deformation capacity by forming in an ultra-low temperature environment. By actively regulating the gradient structure and controlling the forming process, thin-walled components with gradient structure and properties can be obtained to meet the service performance requirements of different positions.

[0037] The present invention also provides a thin-walled component with gradient structure and properties, which is prepared by the preparation method of the thin-walled component with gradient structure and properties as described above. The grain size of the weak deformation region, the intermediate region and the strong deformation region of the thin-walled component with gradient structure and properties are different. The grain size of the weak deformation region is smaller than the grain size of the intermediate region and the grain size of the intermediate region is smaller than the grain size of the strong deformation region.

[0038] The beneficial effects of the thin-walled component with gradient structure and properties provided by the present invention compared with the prior art are the same as the preparation method of the thin-walled component with gradient structure and properties, and will not be repeated here. Attached Figure Description

[0039] Figure 1 This is a schematic flowchart of a method for forming a thin-walled component with gradient structure and properties according to an embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of the process of processing raw materials through SPD and turning in an embodiment of the present invention;

[0041] Figure 3 This is a schematic diagram of a typical thin-walled member with equal thickness plate deep drawing in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of a typical curved surface deep-drawn thin-walled component in an embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of a thin-walled component with local features in an embodiment of the present invention;

[0044] Figure 6 This is a schematic diagram of the process of the blank material undergoing oscillating and rolling treatment and deep drawing through a die in Embodiment 1 of the present invention. Detailed Implementation

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below.

[0046] It should be noted that, unless otherwise specified, the features in the embodiments of this invention can be combined with each other. The terms "comprising," "including," "containing," and "having" are non-limiting, meaning that other steps and other components that do not affect the results can be added. The above terms cover the terms "composed of" and "substantially composed of." Unless otherwise specified, the materials, equipment, and reagents are commercially available.

[0047] This invention provides a method for forming thin-walled components with gradient structure and properties, such as... Figure 1 As shown, it includes the following steps:

[0048] Step S1: Obtain the dimensions and shape of the blank material based on the three-dimensional model of the formed thin-walled component;

[0049] Step S2: Obtain the deformation priority of different regions in the formed thin-walled component, and divide the different regions of the formed thin-walled component into weak deformation region, intermediate region and strong deformation region.

[0050] Step S3: Based on the deformation priority of different regions in the formed thin-walled component, and the size and shape of the blank material, obtain the corresponding positions of the weak deformation region, the intermediate region and the strong deformation region in the blank material;

[0051] Step S4: Obtain the first stress value, second stress value, and third stress value of the weak deformation region, the intermediate region, and the strong deformation region during the deformation process. Based on the first stress value, the second stress value, and the third stress value, determine the grain size of different regions in the blank material to obtain a blank material design drawing with a gradient structure.

[0052] Step S5: Plastic process the homogeneous slab according to the blank material design drawing to obtain a gradient structure material with fine local grains, wherein the blank material is made of aluminum, aluminum alloy or stainless steel.

[0053] Step S6: The gradient structure material is shaped under ultra-low temperature conditions to obtain the shaped gradient structure material;

[0054] Step S7: The formed gradient structure material is heat-treated to modify it, thereby obtaining a thin-walled component with gradient structure and properties.

[0055] This invention, through reverse engineering of the formed thin-walled component, obtains the dimensions and structure of the blank material used to prepare the component. Then, based on the deformation priority of the formed thin-walled component during the forming process and practical applications, it is divided into weak deformation zones, intermediate zones, and strong deformation zones, and these zones are mapped onto the blank material. The stress values ​​of different zones determine the grain size, thus obtaining a blank material design drawing to guide the processing of the blank material. In this process, the blank material can be reverse-engineered according to the forming process and application scenario of the formed thin-walled component, proactively designing the blank material based on the required performance of the component to ensure performance meets the requirements. Based on the blank material design drawing, the homogeneous slab is plastically processed to give different grain sizes in different regions. Forming is then performed at ultra-low temperatures, significantly enhancing its strength and work hardening ability, providing sufficient deformation capacity, and effectively suppressing defects such as structural damage. Finally, heat treatment modification is used to adjust the properties, resulting in a thin-walled component with gradient microstructure and properties. The forming method for thin-walled components with gradient structure and properties provided in this invention can obtain a blank material design drawing through reverse design, adjust the gradient structure and properties of different regions of the blank material based on the blank material design drawing, and improve the deformation capacity by forming in an ultra-low temperature environment. By actively regulating the gradient structure and controlling the forming process, thin-walled components with gradient structure and properties can be obtained to meet the service performance requirements of different positions.

[0056] In step S1, the three-dimensional model of the formed thin-walled component is unfolded according to the law of constant volume to obtain the size and shape of the blank material.

[0057] During pressure processing, if the density of the material does not change, the volume before and after deformation will not change. By applying the law of constant volume, the shape of the formed thin-walled component can be reverse-engineered to obtain the dimensions and shape of the blank material used to prepare the formed thin-walled component. Obtaining the dimensions and shape of the blank material facilitates design based on it.

[0058] In step S2, based on the material flow criteria and finite element simulation, the deformation priority of different regions in the formed thin-walled component is obtained. The region that is prone to plastic deformation during the forming process is designated as the weak deformation region, the region that is not prone to plastic deformation during the forming process is designated as the strong deformation region, and the region in the formed thin-walled component other than the weak deformation region and the strong deformation region is designated as the intermediate region.

[0059] During the forming process, areas prone to plastic deformation are typically stress concentration areas, designated as weak deformation zones (i.e., Zone I). Areas less prone to deformation are designated as strong deformation zones (i.e., Zone III). Areas other than these two zones are designated as intermediate zones (i.e., Zone II). Alternatively, the deformation priority of different zones can be determined based on the load conditions of different parts of the thin-walled component during service. Areas requiring high load-bearing capacity are designated as weak deformation zones, while areas not requiring high load-bearing capacity are designated as strong deformation zones. Areas other than these two zones are designated as intermediate zones.

[0060] For example, when forming a cylindrical component by stretching, the area corresponding to the fillet of the punch, the transition area of ​​the curved component, and the areas with characteristic shapes such as local fillets and bulges are subject to greater stress due to the specificity of their geometry, making them prone to deformation and resulting in thinning of the wall thickness. These areas are called weak deformation areas (area I). ​​Correspondingly, when forming a rigid die by deep drawing, the material at the bottom of the punch and in the flange area is not easily deformed due to friction. These areas are called strong deformation areas (area III). The areas other than the weak deformation areas and strong deformation areas are called intermediate areas (area II).

[0061] Among them, the material flow criterion refers to the assumption of the direction of the plastic deformation increment after the material reaches yield, that is, a proportional relationship in which the components of the plastic deformation increment change.

[0062] In step S3, based on the deformation priority of different regions in the formed thin-walled component and the size and shape of the blank material, reverse processing is performed using finite element simulation to obtain the corresponding positions of the weak deformation region, the intermediate region, and the strong deformation region in the blank material.

[0063] In other words, after determining the weak deformation zone, intermediate zone, and strong deformation zone based on the formed thin-walled component, finite element simulation calculations are performed using a computer to calculate the corresponding positions of different regions in the blank material, which facilitates the design of the blank material.

[0064] In step S4, the first stress value, the second stress value, and the third stress value of the weak deformation zone, the intermediate region, and the strong deformation zone during the deformation process are obtained;

[0065] The grain size in different regions of the blank material is determined according to Formula 1, which includes:

[0066] d Ⅰ -1 / 2 :d Ⅱ -1 / 2 :d Ⅲ -1 / 2 =σ Ⅰ -σ0:σ Ⅱ -σ0:σⅢ -σ0;

[0067] In the formula, d Ⅰ d Ⅱ d Ⅲ σ represents the required grain size for the weak deformation region, the intermediate region, and the strong deformation region, respectively. Ⅰ σ Ⅱ σ Ⅲ These represent the first stress value, the second stress value, and the third stress value, respectively, and σ0 represents the material constant of the blank material;

[0068] Based on the grain size of different regions in the blank material, a design drawing of the blank material with a gradient structure is obtained.

[0069] Specifically, the stress values ​​of different regions during the deformation process are extracted using the finite element simulation method, and then the grain size to be achieved in each region is determined according to Formula 1 above.

[0070] It should be noted that, under normal circumstances, d Ⅲ The initial grain size of the blank material is known data.

[0071] In step S5, according to the blank material design drawing, the weak deformation zone and the intermediate zone in the homogeneous slab are subjected to severe plastic deformation processing to obtain the gradient structure material with locally fine grain size.

[0072] Among them, the severe plastic deformation (SPD) processing methods include friction stirring, oscillating rolling and rotary rolling. According to the grain size requirements of the weak deformation area and the intermediate area in the blank material design drawing, the appropriate SPD processing method is selected, and the grain size of different areas is controlled by controlling the amount of deformation.

[0073] After processing by SPD, the blank material can be actively controlled before forming to obtain a blank material with a gradient structure.

[0074] Gradient microstructure materials with fine local grain sizes refer to materials in which different regions have different grain sizes, with the grain size in the weak deformation region and the intermediate region being smaller than that in the strong deformation region, thus giving different regions different forming properties.

[0075] It should be noted that, under normal circumstances, the grain size of the strong deformation region is the initial grain size of the blank material, while the grain size of the weak deformation region and the intermediate region is determined by the above formula. The resulting gradient microstructure material has a grain size in the weak deformation region and the intermediate region that is smaller than the grain size in the strong deformation region, which is a gradient microstructure material with locally small grain size.

[0076] In one embodiment, after step S5 and before step S6, the method further includes:

[0077] The gradient structure material is annealed to obtain an annealed gradient structure material.

[0078] Annealing can improve the reduced forming ability of weak and intermediate areas caused by SPD processing without reducing the strength of the weak and intermediate areas.

[0079] In step S6, the gradient structure material is shaped under ultra-low temperature conditions to obtain the shaped gradient structure material.

[0080] For gradient microstructure materials such as aluminum, aluminum alloys, or stainless steel, forming at ultra-low temperatures can significantly enhance the strength and work hardening capacity of the gradient microstructure materials, provide sufficient deformation capacity, and effectively suppress defects such as microstructure damage.

[0081] For example, the temperature range of the ultra-low temperature environment is -150℃ to -196℃, which can be achieved by filling with liquid nitrogen.

[0082] Further, step S6 includes:

[0083] The gradient structure material is turned to obtain a gradient structure material blank with a uniform thickness in the length direction. The areas corresponding to the weak deformation area and the middle area in the gradient structure material blank are placed in an ultra-low temperature environment for cooling and forming at the same time to obtain the formed gradient structure material.

[0084] When it is necessary to form a plate of equal thickness, the gradient structure material is first turned before forming to obtain a plate blank of gradient structure material with consistent thickness in the length direction (i.e., an equal thickness plate blank).

[0085] Then, the weak and intermediate regions of the gradient microstructure material slab are cooled in an ultra-low temperature environment while being formed. By locally cooling the weak and intermediate regions, the deformation resistance of the material in these regions can be further improved under the dual effects of the gradient microstructure and the gradient temperature. The strength difference brought about by fine grain strengthening and low temperature strengthening can fully compensate for the stress difference brought about by the forming load, making the deformation distribution of the entire blank material more uniform, thereby meeting the forming requirements of complex thin-walled components.

[0086] It should be understood that the need to turn the gradient structure material depends on the structure of the final thin-walled component. When it is necessary to use a slab of equal thickness for preparation, it is necessary to turn it first and then form it. However, when it is necessary to use a plate of varying thickness for preparation, it is not necessary to turn it first and it can be formed directly.

[0087] Figure 2 This diagram illustrates the material processing steps for a blank. A homogeneous slab is used as the blank material. Initially, the homogeneous slab has a uniform thickness along its length, with a thickness of t0. The grain size is the same in all regions. Based on the distribution of the weak deformation region, intermediate region, and strong deformation region in the blank material design drawing, the intermediate region of the homogeneous slab is subjected to SPD processing, reducing its thickness to t1 to form a weak deformation region. The two ends of the homogeneous slab retain their original thickness t0, forming strong deformation regions. An intermediate region is formed between the weak deformation region and the strong deformation region. Then, mechanical turning is performed with the thickness t1 of the weak deformation region as a reference to obtain a gradient microstructure material slab (equal thickness slab) with a thickness of t1.

[0088] In step S7, the formed gradient structure material is subjected to solution treatment and aging treatment to obtain a thin-walled component with gradient structure and properties.

[0089] Based on the service requirements of the thin-walled component with gradient structure and properties, different heat treatment modification processes are selected for treatment, such as solution treatment and aging treatment, to adjust the microstructure and properties of the gradient structure material after forming, so as to obtain a thin-walled component that meets the requirements in both shape and properties.

[0090] Furthermore, for heat-treatable aluminum alloy thin-walled components, thermal stress deformation easily occurs during quenching after forming due to the extremely rapid cooling rate, leading to a decrease in the dimensional accuracy of the thin-walled components. At the same time, grain growth is prone to occur during solution treatment after severe deformation in the annealed state. To avoid the above defects, solution treatment can be performed on the blank material before SPD processing, and then aging treatment can be performed after forming to ensure the dimensional accuracy and mechanical performance requirements of the thin-walled components.

[0091] Another embodiment of the present invention provides a thin-walled component with gradient structure and properties, which is prepared by the method for preparing a thin-walled component with gradient structure and properties as described above. The grain sizes of the weak deformation region, the intermediate region and the strong deformation region of the thin-walled component with gradient structure and properties are different. The grain size of the weak deformation region is smaller than the grain size of the intermediate region and the grain size of the intermediate region is smaller than the grain size of the strong deformation region.

[0092] For example, thin-walled components with gradient structure and properties include typical equal-thickness plate deep-drawn thin-walled components, typical curved surface deep-drawn thin-walled components, or thin-walled components with local features, the structural schematic diagrams of which are shown below. Figure 3 , Figure 4 and Figure 5 As shown, the size of the hexagon in the cross-section represents the grain size. From Figures 3-5As can be seen, depending on the different structures of different thin-walled components, the distribution of their weak deformation zone, intermediate zone and strong deformation zone is also different. Different regions have different grain sizes to provide gradient structure and properties.

[0093] The beneficial effects of the thin-walled component with gradient structure and properties provided in this embodiment of the invention compared to the prior art are the same as the preparation method of the thin-walled component with gradient structure and properties, and will not be repeated here.

[0094] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to the manufacturer's recommended conditions. It should be noted that all percentages in the embodiments are by weight.

[0095] Example 1

[0096] Fuel tanks are critical components on rockets and various missiles, consisting of four welded parts: the tank bottom, the cylindrical section, the short shell, and the fork-shaped ring. The fork-shaped ring connects the other three parts. This embodiment achieves integrated forming of the tank bottom and the fork-shaped ring using a thin-walled component forming method with gradient structure and performance. The selected material is 2219 aluminum alloy, commonly used in award-winning fuel tanks in current launch vehicles. The target thin-walled component is a semi-ellipsoid, with the following dimensions: opening diameter 3350mm, axis-to-length ratio 1.6, central thin-wall thickness 8mm, and edge thick-wall thickness 3-5 times that of the thin-wall thickness.

[0097] The specific preparation steps include:

[0098] 1.1. Based on the law of constant volume, the 3D model of the formed thin-walled component is unfolded to obtain the dimensions and shape of the blank material. The blank material is a radially thick plate with one side being flat and the other side being non-planar. The overall outer diameter is Φ4200mm, the thickness of the edge thick-walled region is 40mm, the inner diameter of the central thin-walled region is Φ3500mm, and the thickness is 8mm. The central thin-walled region and the edge thick-walled region are connected by a sloping transition, and the angle between the sloping surface and the plate plane is 10°-20°.

[0099] 1.2. Based on the material flow criteria and finite element simulation, the deformation priority of different regions in the formed thin-walled component is obtained. The region that is prone to plastic deformation during the forming process is designated as the weak deformation region (region I), which is the central thin-walled region in step 1.1. The region that is not prone to plastic deformation during the forming process is designated as the strong deformation region (region III), which corresponds to the edge thick-walled region in step 1.1. The region in the formed thin-walled component other than the weak deformation region and the strong deformation region is designated as the intermediate region (region II), which is the inclined transition region in step 1.1.

[0100] 1.3. Using conventional solution-treated homogeneous 2219 aluminum alloy as blank material, the blank material model was used to simulate the deep drawing of thin-walled components after forming. During the simulation, the solution treatment parameters were 535℃ for 1 hour. The deep drawing process adopted a central local cooling method to improve the deformation resistance and forming limit of Zone I and Zone II.

[0101] 1.4 Extract the stress distribution of the thin-walled component after forming simulation, and obtain the first stress value, second stress value, and third stress value corresponding to region I, region II, and region III respectively. Calculate the grain size of each region according to the following formula:

[0102] d Ⅰ -1 / 2 :d Ⅱ -1 / 2 :d Ⅲ -1 / 2 =σ Ⅰ -σ0:σ Ⅱ -σ0:σ Ⅲ -σ0;

[0103] In the formula, d Ⅰ d Ⅱ d Ⅲ σ represents the required grain size for regions I, II, and III, respectively. Ⅰ σ Ⅱ σ Ⅲ These represent the first stress value, the second stress value, and the third stress value, respectively, and σ0 represents the material constant of the blank material; specifically, in this embodiment, σ0 is 10 MPa, σ Ⅰ and v Ⅲ The pressures are 460 MPa and 100 MPa, respectively, while σ Ⅱ Between 150MPa and 460MPa;

[0104] Among them, the grain size of region III is the original grain size of the blank material, which is about 25 μm. After calculation, the grain size of region II is 1 to 10 μm, and the grain size of region I is about 1 μm.

[0105] 1.5. Keep the raw material at 535℃ for 1 hour, and then put it into water for solution treatment;

[0106] 1.6. Based on the grain size of each region determined in step 1.4, SPD processing is performed on regions I and II of the blank material with an initial thickness of 40mm using a swivel rolling process. The grain size of different regions is controlled by controlling the amount of deformation. After swivel rolling, the thickness of the central thin-walled region is reduced to 8mm, and the grain size is about 1μm. The thickness of region III remains basically unchanged, and the grain size is maintained at about 25μm.

[0107] The thickness of region II is gradient-distributed, and the grain size is 1–10 μm, resulting in a gradient-structured material.

[0108] 1.7 The gradient structure material was kept at 200℃ for 1 hour and then air-cooled for annealing to obtain an annealed gradient structure material.

[0109] 1.8 Place the annealed gradient material on the mold, fill the cavities of the die and punch with liquid nitrogen for cooling, so that the I and II zones of the annealed gradient material are kept at -150℃ to -196℃. Set an insulation layer between the mold cavity and the flange to keep the temperature of the III zone at room temperature. Then apply a blank holder force to perform deep drawing to obtain the formed gradient material.

[0110] 1.9 The formed gradient structure material is kept at 175℃ for 18 hours for heat treatment modification to achieve the peak aging state at service, resulting in a thin-walled component with integrated box bottom and fork ring, which has gradient structure and properties.

[0111] Figure 6 This is a schematic diagram of the rolling process and deep drawing process in this embodiment. Figure 6 The upper left image is a schematic diagram of the milling process. Figure 6 The lower left image is a schematic diagram of deep drawing. Figure 6 The diagram on the right shows the process of forming a gradient microstructure material from raw material through a rolling and deep drawing process, and the resulting gradient microstructure material. Figure 6 As can be seen, after the blank material is processed by the rolling process, different regions have different grain sizes, forming a gradient structure material. After deep drawing, the resulting gradient structure material has gradient structure and properties, which meet the performance requirements during service.

[0112] Although the invention has been disclosed above, the scope of protection of this invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this invention, and all such changes and modifications will fall within the scope of protection of this invention.

Claims

1. A method for forming a thin-walled component with gradient structure and properties, characterized in that, Includes the following steps: Step S1: Obtain the dimensions and shape of the blank material based on the three-dimensional model of the formed thin-walled component; Step S2: Obtain the deformation priority of different regions in the formed thin-walled component, and divide the different regions of the formed thin-walled component into weak deformation region, intermediate region and strong deformation region. Step S3: Based on the deformation priority of different regions in the formed thin-walled component, and the size and shape of the blank material, obtain the corresponding positions of the weak deformation region, the intermediate region and the strong deformation region in the blank material; Step S4: Obtain the first stress value, second stress value, and third stress value of the weak deformation region, the intermediate region, and the strong deformation region during the deformation process. Based on the first stress value, the second stress value, and the third stress value, determine the grain size of different regions in the blank material to obtain a blank material design drawing with a gradient structure. Step S5: Plastic process the homogeneous slab according to the blank material design drawing to obtain a gradient structure material with fine local grains, wherein the blank material is made of aluminum, aluminum alloy or stainless steel. Step S6: The gradient structure material is shaped under ultra-low temperature conditions to obtain the shaped gradient structure material; Step S7: The formed gradient structure material is heat-treated to modify it, thereby obtaining a thin-walled component with gradient structure and properties.

2. The forming method for a thin-walled component with gradient structure and properties according to claim 1, characterized in that, Step S1 includes: unfolding the three-dimensional model of the formed thin-walled component according to the law of constant volume to obtain the size and shape of the blank material.

3. The forming method for a thin-walled component with gradient structure and properties according to claim 1, characterized in that, Step S2 includes: obtaining the deformation priority of different regions in the formed thin-walled component according to the material flow criterion and finite element simulation method, taking the region that is easy to undergo plastic deformation during the forming process as the weak deformation region, taking the region that is not easy to undergo plastic deformation during the forming process as the strong deformation region, and taking the region in the formed thin-walled component other than the weak deformation region and the strong deformation region as the intermediate region.

4. The forming method for a thin-walled component with gradient structure and properties according to claim 1, characterized in that, Step S3 includes: based on the deformation priority of different regions in the formed thin-walled component, and the size and shape of the blank material, reverse processing is performed using finite element simulation to obtain the corresponding positions of the weak deformation region, the intermediate region, and the strong deformation region in the blank material.

5. The forming method for a thin-walled component with gradient structure and properties according to claim 1, characterized in that, Step S4 includes: The first stress value, the second stress value, and the third stress value of the weak deformation region, the intermediate region, and the strong deformation region during the deformation process are obtained; The grain size in different regions of the blank material is determined according to Formula 1, which includes: ； In the formula, , , These represent the required grain sizes for the weak deformation region, the intermediate region, and the strong deformation region, respectively. , , These represent the first stress value, the second stress value, and the third stress value, respectively. This represents the material constant of the blank material; Based on the grain size of different regions in the blank material, a design drawing of the blank material with a gradient structure is obtained.

6. The forming method of the thin-walled component with gradient structure and properties according to claim 1, characterized in that, Step S5 includes: according to the blank material design drawing, performing severe plastic deformation processing on the weak deformation zone and the intermediate region in the homogeneous slab to obtain the gradient structure material with locally fine grain size.

7. The forming method for a thin-walled component with gradient structure and properties according to claim 1, characterized in that, Step S6 includes: turning the gradient structure material to obtain a gradient structure material blank with a uniform thickness in the length direction; placing the areas corresponding to the weak deformation area and the middle area in the gradient structure material blank in an ultra-low temperature environment for cooling while forming, to obtain the formed gradient structure material.

8. The forming method of the thin-walled component with gradient structure and properties according to claim 1, characterized in that, Step S7 includes: performing solution treatment and aging treatment on the formed gradient structure material to obtain a thin-walled component with gradient structure and properties.

9. The forming method for a thin-walled component with gradient structure and properties according to claim 1, characterized in that, After step S5 and before step S6, the method further includes: annealing the gradient structure material to obtain an annealed gradient structure material. Step S6 includes: turning the annealed gradient microstructure material and then forming it under ultra-low temperature conditions to obtain the formed gradient microstructure material.

10. A thin-walled component with gradient structure and properties, characterized in that, The thin-walled component with gradient structure and properties is obtained by forming method according to any one of claims 1-9. The grain size of the weak deformation region, the intermediate region and the strong deformation region of the thin-walled component with gradient structure and properties are different. The grain size of the weak deformation region is smaller than the grain size of the intermediate region and the grain size of the intermediate region is smaller than the grain size of the strong deformation region.

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