An additive manufacturing method for a gradient material

Abstract

The application discloses an additive manufacturing method for gradient materials, and relates to the technical field of additive manufacturing, and aims to solve the problem that although a part made of a single high-performance material meets work requirements, the high-performance material used for manufacturing the part is high in cost. The additive manufacturing method for gradient materials comprises the following steps: processing two kinds of titanium alloy materials by using an additive manufacturing method to obtain a part blank; the two kinds of titanium alloy materials form a gradient material; performing rough machining treatment on the part blank to obtain a first preform; performing heat treatment on the first preform according to a heat treatment strategy to obtain a second preform; and performing finish machining treatment on the second preform to obtain a part.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology, and more particularly to an additive manufacturing method for gradient materials. Background Technology

[0002] Because of its excellent properties such as high specific strength and good corrosion resistance, titanium alloys are widely used in the manufacture of parts for industries such as aviation, aerospace and shipbuilding.

[0003] As product performance in industries such as aviation, aerospace, and shipbuilding is upgraded and iterated, the working environments of parts are becoming increasingly complex. Currently, parts are typically made using a single high-performance material.

[0004] While parts made from a single high-performance material may meet the operational requirements, the high-performance material used to make these parts is very expensive. Summary of the Invention

[0005] The purpose of this invention is to provide an additive manufacturing method for gradient materials, which enables parts to meet working requirements while saving the total cost of materials used to manufacture the parts.

[0006] To achieve the above objectives, the present invention provides an additive manufacturing method for gradient materials. This additive manufacturing method for gradient materials includes:

[0007] Two titanium alloy materials are processed using additive manufacturing to obtain part blanks; the two titanium alloy materials are formed into a gradient material.

[0008] The part blank is rough-machined to obtain the first preform;

[0009] The first preform is heat-treated according to the heat treatment strategy to obtain the second preform;

[0010] The second preform is then precision machined to obtain the part.

[0011] Compared to existing technologies, the additive manufacturing method for gradient materials provided by this invention uses two titanium alloy materials to create a gradient material for the part blank. This allows for the selection of materials for different regions of the part based on their actual operating environment. For example, regions with normal operating temperatures can be made of conventional materials, regions with high operating temperatures can be made of high-temperature resistant materials, and regions with low operating temperatures can be made of low-temperature resistant materials. This not only ensures the quality and performance of the final part, meeting operational requirements, but also saves on the total material cost compared to existing technologies that use expensive, high-performance (e.g., high-temperature or low-temperature resistant) materials for part fabrication. Attached Figure Description

[0012] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0013] Figure 1 This is a schematic flowchart of an additive manufacturing method for gradient materials in an embodiment of the present invention;

[0014] Figure 2 This is a graph showing the relationship between time and temperature in the solution treatment or high-temperature annealing process in the embodiments of the present invention;

[0015] Figure 3 This is a graph showing the relationship between time and temperature in the aging process or low-temperature annealing process in the embodiments of the present invention.

[0016] Figure label:

[0017] 1-Fourth temperature, 2-Second temperature, 3-Third temperature, 4-First temperature, 5-Second preset temperature. Detailed Implementation

[0018] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0020] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. "Several" means one or more, unless otherwise explicitly specified.

[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] In conjunction with the background technology section, as product performance is iterated and upgraded, the operating temperature of parts is increasing, placing more stringent requirements on the materials used to manufacture these parts. However, conventional titanium alloys are inexpensive but cannot meet the required operating temperatures. High-temperature titanium alloys can meet even higher operating temperature requirements, but they are expensive.

[0024] To address the aforementioned technical problems, this invention provides an additive manufacturing method for gradient materials. See also... Figure 1 The additive manufacturing method for gradient materials includes:

[0025] Step 101: Two titanium alloy materials are processed using additive manufacturing to obtain a part blank; the two titanium alloy materials form a gradient material.

[0026] For example, the two types of titanium alloy materials mentioned above can include conventional titanium alloy materials and high-temperature titanium alloy materials. In this case, the areas of the part operating at normal temperatures are made of conventional materials, while the areas operating at high temperatures are made of high-temperature resistant materials. For instance, typical grades of the aforementioned conventional titanium alloy materials are TC4, TA15, and TC11. Typical grades of high-temperature titanium alloy materials are TC25, TC25G, TA32, TA33, and Ti2AlNb. Of course, the aforementioned titanium alloy materials can also include low-temperature titanium alloy materials, etc.

[0027] As one possible implementation, processing two titanium alloy materials using additive manufacturing methods to obtain part blanks includes: processing two titanium alloy materials using laser deposition and / or arc additive manufacturing to obtain part blanks.

[0028] At this point, the resulting part blanks can meet the requirements for complex and lightweight part structures. It should be understood that the aforementioned laser deposition manufacturing and / or arc additive manufacturing methods can be used not only to manufacture parts for aerospace applications, but also to manufacture some frame beams and cylindrical parts for weaponry, rockets, and manned spacecraft. Furthermore, laser deposition manufacturing and / or arc additive manufacturing also offer advantages such as high manufacturing efficiency and low overall cost.

[0029] As one possible implementation, the additive manufacturing method for gradient materials, before rough machining the part blank, also includes stress relief treatment of the part blank. This can reduce or eliminate the stress in the part blank, thereby reducing or preventing deformation and cracking of the final manufactured part, improving part quality and yield.

[0030] The stress relief process is described below using two possible scenarios as examples. It should be understood that the following description is for comprehension purposes only and is not intended to limit the specific application of the process.

[0031] Example 1: When processing two types of titanium alloy materials using laser deposition manufacturing and / or arc additive manufacturing, stress relief treatments are performed intermittently during the part blank forming process, depending on the structure and stress level of the part blank.

[0032] The stress relief methods mentioned above include: stress relief annealing, ultrasonic stress relief, or in-situ stress relief treatment.

[0033] Example 2: Stress relief treatment for completed part blanks. Stress relief methods include stress-relief annealing and ultrasonic stress relief. The process parameters for stress-relief annealing are: temperature greater than or equal to 480℃ and less than or equal to 650℃, time greater than or equal to 2 hours and less than or equal to 6 hours, and air cooling or a slower cooling rate.

[0034] It should be noted that if the residual stress in the blank forming process of the part in Example 1 has been eliminated, the stress relief step in Example 2 can be omitted.

[0035] Step 102: Perform rough machining on the part blank to obtain the first preform;

[0036] For example, based on the size requirements of the part, the loose powder and most of the machining allowance on the surface of the part blank are removed.

[0037] Step 103: Perform heat treatment on the first preform according to the heat treatment strategy to obtain the second preform;

[0038] Step 104: Perform finishing processing on the second preform to obtain the part.

[0039] For example, according to the drawing requirements, the second prefabricated part is processed into a finished product state to obtain a part.

[0040] Based on the preceding description, the heat treatment described above can regulate the microstructure and mechanical properties of the second preform, thereby regulating the microstructure and mechanical properties of the final part.

[0041] In the additive manufacturing method for gradient materials provided in this invention, the part blank is made of two titanium alloy materials, forming a gradient material. Therefore, the materials used to manufacture different regions of the part can be selected based on the actual working environment of those regions. For example, regions with normal operating temperatures can be made of conventional materials, regions with high operating temperatures can be made of high-temperature resistant materials, and regions with low operating temperatures can be made of low-temperature resistant materials. This not only ensures the quality and performance of the final part, meeting operational requirements, but also saves on the total material cost compared to existing technologies that use expensive, high-performance (e.g., high-temperature or low-temperature resistant) materials for part manufacturing.

[0042] As one possible implementation, the above heat treatment strategy is a solution aging strategy or a double annealing strategy.

[0043] After heat treatment of the first preform using a solution aging strategy, the resulting second preform has the advantage of high strength, which in turn gives the final part a high strength advantage.

[0044] By employing a double annealing strategy to heat-treat the first preform, the resulting second preform possesses advantages in both ductility and toughness, which in turn enables the final part to also possess these advantages.

[0045] In summary, depending on the requirements of the final molded part for high strength or ductility, a solution aging strategy or a double annealing strategy can be selected for heat treatment of the first preform.

[0046] The specific operational steps of the solution aging strategy and the double annealing strategy are discussed below. It should be understood that the following descriptions are for comprehension purposes only and are not intended to limit the specific application of the strategy.

[0047] For solution aging strategies:

[0048] See Figure 2 and Figure 3 Step 103: Heat-treat the first preform according to the heat treatment strategy (i.e., solution aging strategy) to obtain the second preform, including:

[0049] Step 103.1: Heat the first preform to a fourth temperature 1 and hold it at the fourth temperature 1 for a fourth time period; the fourth temperature 1 is less than the lowest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials.

[0050] In one alternative approach, the high-temperature annealing temperature of the aforementioned titanium alloy material is greater than or equal to a and less than or equal to b; wherein a = recrystallization temperature of the titanium alloy material - 50℃, and b = solidus temperature of the titanium alloy material - 100℃.

[0051] For example, the first preform is heated to a fourth temperature in the furnace. The fourth temperature is greater than or equal to 500°C and less than or equal to 600°C; the fourth time period is greater than or equal to 0.5 hours and less than or equal to 1 hour. For example, the fourth temperature is 500°C, 520°C, 540°C, 550°C, 570°C, 580°C, 596°C, or 600°C, etc. The fourth time period is 0.5 hours, 0.56 hours, 0.7 hours, 0.85 hours, 0.93 hours, or 1 hour, etc. When both materials used to make the part are titanium alloys (the specific properties of titanium alloys are not specifically limited here), the high-temperature annealing temperature of the titanium alloy is greater than or equal to 750°C and less than or equal to 1000°C.

[0052] Step 103.2: Perform at least two oscillating temperature treatments on the first preform to obtain the third preform;

[0053] By employing oscillating temperature treatment, the gradient material interface can interactively grow to form a serrated interface, resulting in better interfacial bonding and improved overall mechanical properties of the third preform, thereby enhancing the overall mechanical properties of the final part. Furthermore, the number of oscillating temperature treatments performed on the first preform is selected based on the structure and wall thickness of the final part. In this embodiment, at least two oscillating temperature treatments are used, ensuring sufficient heating of the first preform, resulting in minimal deformation, low residual stress, and excellent mechanical properties.

[0054] In one optional manner, each oscillating temperature process includes:

[0055] The first preform is heated to a second temperature 2 and held at the second temperature 2 for a second time period; the second temperature is the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials. At this time, the metallurgical kinetics of grain growth can be stimulated by the short-term high-temperature treatment, which helps to homogenize the microstructure of the titanium alloy with a higher β transformation temperature.

[0056] The following explanation uses Type A and Type B titanium alloys as examples to illustrate that "the second temperature is the highest of the solution treatment temperature and / or high-temperature annealing temperature of the two titanium alloys." It should be understood that the following description is for comprehension purposes only and is not intended to limit the application of any specific material.

[0057] (1) When Class A titanium alloy materials only have a solution temperature and Class B titanium alloy materials only have a high temperature annealing temperature, the second temperature is the highest of the solution temperature of Class A titanium alloy materials and the high temperature annealing temperature of Class B titanium alloy materials.

[0058] (2) When both Type A titanium alloy materials and Type B titanium alloy materials have only a solution temperature, the second temperature is the highest of the solution temperature of Type A titanium alloy materials and the solution temperature of Type B titanium alloy materials.

[0059] (3) When Class A titanium alloy materials only have a high temperature annealing temperature and Class B titanium alloy materials only have a high temperature annealing temperature, the second temperature is the highest of the high temperature annealing temperature of Class A titanium alloy materials and the high temperature annealing temperature of Class B titanium alloy materials.

[0060] (4) When Class A titanium alloy materials only have a high-temperature annealing temperature and Class B titanium alloy materials only have a solution treatment temperature, the second temperature is the highest of the high-temperature annealing temperature of Class A titanium alloy materials and the solution treatment temperature of Class B titanium alloy materials.

[0061] (5) When Class A titanium alloy materials have both high temperature annealing temperature and solution treatment temperature, and when Class B titanium alloy materials have both high temperature annealing temperature and solution treatment temperature, the second temperature is the highest of the above four temperatures.

[0062] (6) When Class A titanium alloy materials only have a solution temperature, and Class B titanium alloy materials have both a high-temperature annealing temperature and a solution temperature, the second temperature is the highest of the three temperatures mentioned above.

[0063] (7) When Class A titanium alloy materials only have a high temperature annealing temperature, and Class B titanium alloy materials have both a high temperature annealing temperature and a solution treatment temperature, the second temperature is the highest of the three temperatures mentioned above.

[0064] (8) When Class A titanium alloy materials have both high-temperature annealing temperature and solution treatment temperature, and Class B titanium alloy materials have only high-temperature annealing temperature, the second temperature is the highest of the above three temperatures.

[0065] (9) When Class A titanium alloy materials have both high-temperature annealing temperature and solution temperature, and Class B titanium alloy materials only have solution temperature, the second temperature is the highest of the above three temperatures.

[0066] It should be noted that the high-temperature annealing temperature of the above-mentioned Class A titanium alloy materials is greater than or equal to a1 and less than or equal to b1; where a1 = recrystallization temperature of Class A titanium alloy materials - 50℃, and b1 = solidus temperature of Class A titanium alloy materials - 100℃.

[0067] The high-temperature annealing temperature of the above-mentioned Class B titanium alloy material is greater than or equal to a2 and less than or equal to b2; wherein, a2 = recrystallization temperature of Class B titanium alloy material -50℃, and b2 = solidus temperature of Class B titanium alloy material -100℃.

[0068] For example, the second time period is 10 minutes. It should be noted that the starting time for the aforementioned second heat preservation time period is when the first preform changes from the fourth temperature to the second temperature. In this embodiment of the invention, the first preform, which is at the fourth temperature 1, is heated to the second temperature 2 and kept at the second temperature 2 for the second time period.

[0069] The first preform, heated to a second temperature 2, is cooled to a third temperature 3 and held at the third temperature 3 for a third time period; the third temperature is the lowest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials. At this time, the metallurgical kinetics of grain growth are suppressed, which helps reduce the risk of coarse grains in titanium alloys with lower β-transformation temperatures. For example, the third time period is 15 minutes.

[0070] The following explanation uses Type A and Type B titanium alloys as examples to illustrate that "the third temperature is the lowest of the solution treatment temperature and / or high-temperature annealing temperature of the two titanium alloys." It should be understood that the following description is for comprehension purposes only and is not intended to limit the application of any specific material.

[0071] (1) When Class A titanium alloy materials only have a solution temperature and Class B titanium alloy materials only have a high-temperature annealing temperature, the third temperature is the lowest of the solution temperature of Class A titanium alloy materials and the high-temperature annealing temperature of Class B titanium alloy materials.

[0072] (2) When both Type A titanium alloy materials and Type B titanium alloy materials have only a solution temperature, the third temperature is the lowest of the solution temperatures of Type A and Type B titanium alloy materials.

[0073] (3) When Class A titanium alloy materials only have a high temperature annealing temperature and Class B titanium alloy materials only have a high temperature annealing temperature, the third temperature is the lowest of the high temperature annealing temperatures of Class A titanium alloy materials and Class B titanium alloy materials.

[0074] (4) When Class A titanium alloy materials only have a high-temperature annealing temperature and Class B titanium alloy materials only have a solution treatment temperature, the third temperature is the lowest of the high-temperature annealing temperature of Class A titanium alloy materials and the solution treatment temperature of Class B titanium alloy materials.

[0075] (5) When Class A titanium alloy materials have both high-temperature annealing temperature and solution treatment temperature, and when Class B titanium alloy materials have both high-temperature annealing temperature and solution treatment temperature, the third temperature is the lowest of the above four temperatures.

[0076] (6) When Class A titanium alloy materials only have a solution temperature, and Class B titanium alloy materials have both a high-temperature annealing temperature and a solution temperature, the third temperature is the lowest of the three temperatures mentioned above.

[0077] (7) When Class A titanium alloy materials only have a high temperature annealing temperature, and Class B titanium alloy materials have both a high temperature annealing temperature and a solution treatment temperature, the third temperature is the lowest of the above three temperatures.

[0078] (8) When Class A titanium alloy materials have both high-temperature annealing temperature and solution treatment temperature, and Class B titanium alloy materials only have high-temperature annealing temperature, the third temperature is the lowest of the above three temperatures.

[0079] (9) When Class A titanium alloy materials have both high-temperature annealing temperature and solution treatment temperature, and Class B titanium alloy materials only have solution treatment temperature, the third temperature is the lowest of the above three temperatures.

[0080] It should be noted that the high-temperature annealing temperature of the above-mentioned Class A titanium alloy materials is greater than or equal to a1 and less than or equal to b1; where a1 = recrystallization temperature of Class A titanium alloy materials - 50℃, and b1 = solidus temperature of Class A titanium alloy materials - 100℃.

[0081] The high-temperature annealing temperature of the above-mentioned Class B titanium alloy material is greater than or equal to a2 and less than or equal to b2; wherein, a2 = recrystallization temperature of Class B titanium alloy material -50℃, and b2 = solidus temperature of Class B titanium alloy material -100℃.

[0082] The cooling rate at which the first preform heated to the second temperature 2 is cooled to the third temperature 3 is greater than or equal to 20℃ / min and less than or equal to 30℃ / min. For example, the cooling rate can be 20℃ / min, 23℃ / min, 25℃ / min, 26℃ / min, 28℃ / min, or 30℃ / min, etc.

[0083] The heating rate when the first preform, cooled to a third temperature 3, is heated to a second temperature 2 is greater than or equal to 20°C / min and less than or equal to 30°C / min. For example, the heating rate can be 20°C / min, 23°C / min, 25°C / min, 26°C / min, 28°C / min, or 30°C / min, etc.

[0084] In one alternative approach, while the first preform heated to the second temperature 2 is kept warm for a second time period, an alternating magnetic field is applied to the space in which the region of the first preform heated to the second temperature 2 has the lowest β transition temperature.

[0085] Under the intervention of an alternating magnetic field, abnormal growth of microstructures during heating can be suppressed, and grains can be refined. For example, coarse microstructures in titanium alloys can be suppressed to optimize the performance of the first preform. Furthermore, since the region in the first preform with the lowest β-transformation temperature is prone to structural deterioration after the aforementioned series of steps, its microstructure is easily coarsened, resulting in the worst performance compared to other regions. Therefore, in this embodiment of the invention, an alternating magnetic field is not applied to all spaces containing the first preform; instead, it is applied only to the space containing the region with the lowest β-transformation temperature within the first preform.

[0086] Based on the previous description, under the dual effects of oscillating temperature treatment and alternating magnetic field strengthening, abnormal growth of microstructures during heating can be further suppressed, grains can be refined, and the overall mechanical properties of the final obtained parts can be further improved.

[0087] Step 103.3: The third preform is subjected to temperature treatment to bring its temperature to the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials (for ease of description, this is referred to as the second preset temperature 5). At this time, rapid cooling at high temperature causes quenching or solution treatment in different regions of the third preform, forming a large number of dislocations inside the material, preparing for subsequent aging treatment.

[0088] For example, the first preform at the third temperature 3 is heated to the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials (i.e., the second preset temperature 5), and held at the second preset temperature 5 for a period of time. The specific holding time can be set according to actual needs and is not specifically limited here.

[0089] Step 103.4: Reduce the temperature of the third preform after temperature treatment to the preset temperature;

[0090] Since the temperature of the third preform is the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials, it is possible to accommodate the cooling temperatures of various materials so that all materials can be cooled to the preset temperature, which facilitates subsequent operations and ensures the quality and performance of the third preform.

[0091] The preset temperature can be set according to actual needs. For example, the preset temperature can be room temperature, slightly higher or lower than room temperature, as long as it meets the actual needs.

[0092] The methods mentioned above for reducing temperature include water cooling, oil cooling, or air cooling.

[0093] Step 103.5: Heat the third preform, which has been cooled to a preset temperature, to a first temperature 4, and hold it at the first temperature 4 for a first time period. The preset temperature is lower than the first temperature 4. The first temperature is the highest of the aging temperature and / or low-temperature annealing temperature of the two titanium alloy materials. At this temperature, the residual stress generated by the solid solution effect inside the material can be reduced, while the strength of the material can be improved. The first time period is greater than or equal to 4 hours and less than or equal to 12 hours. For example, the first time period can be 4 hours, 5 hours, 7 hours, 8 hours, 11 hours, or 12 hours, etc.

[0094] In one alternative approach, the low-temperature annealing temperature of the titanium alloy material is greater than or equal to 0.3Tb and less than or equal to 0.6Tb; where Tb represents the solidus temperature of the titanium alloy material.

[0095] For example, when both materials used to make the part are titanium alloys (the specific properties of titanium alloys are not specifically limited here), the low-temperature annealing temperature of the titanium alloy is greater than or equal to 450°C and less than 750°C.

[0096] The following explanation uses Class A and Class B titanium alloys as examples to illustrate the concept that "the first temperature is the highest of the aging temperature and / or low-temperature annealing temperature of the two titanium alloys." It should be understood that the following description is for comprehension purposes only and is not intended to limit the application of any specific material.

[0097] (1) When Class A titanium alloy materials only have an aging temperature and Class B titanium alloy materials only have a low-temperature annealing temperature, the first temperature is the highest of the aging temperature of Class A titanium alloy materials and the low-temperature annealing temperature of Class B titanium alloy materials.

[0098] (2) When both Type A titanium alloy materials and Type B titanium alloy materials have only an aging temperature, the first temperature is the highest of the aging temperatures of Type A and Type B titanium alloy materials.

[0099] (3) When Class A titanium alloy materials only have a low-temperature annealing temperature and Class B titanium alloy materials only have a low-temperature annealing temperature, the first temperature is the highest of the low-temperature annealing temperatures of Class A titanium alloy materials and Class B titanium alloy materials.

[0100] (4) When Class A titanium alloy materials only have a low-temperature annealing temperature and Class B titanium alloy materials only have an aging temperature, the first temperature is the highest of the low-temperature annealing temperature of Class A titanium alloy materials and the aging temperature of Class B titanium alloy materials.

[0101] (5) When Class A titanium alloy materials have both low-temperature annealing temperature and aging temperature, and when Class B titanium alloy materials have both low-temperature annealing temperature and aging temperature, the first temperature is the highest of the above four temperatures.

[0102] (6) When Class A titanium alloy materials only have an aging temperature, and Class B titanium alloy materials have both a low-temperature annealing temperature and an aging temperature, the first temperature is the highest of the three temperatures mentioned above.

[0103] (7) When Class A titanium alloy materials only have a low-temperature annealing temperature, and Class B titanium alloy materials have both a low-temperature annealing temperature and an aging temperature, the first temperature is the highest of the three temperatures mentioned above.

[0104] (8) When Class A titanium alloy materials have both low-temperature annealing temperature and aging temperature, and Class B titanium alloy materials have only low-temperature annealing temperature, the first temperature is the highest of the above three temperatures.

[0105] (9) When Class A titanium alloy materials have both low-temperature annealing temperature and aging temperature, and Class B titanium alloy materials only have aging temperature, the first temperature is the highest of the above three temperatures.

[0106] It should be noted that the low-temperature annealing temperature of the above-mentioned Class A titanium alloy materials is greater than or equal to 0.3Tb1 and less than or equal to 0.6Tb1; where Tb1 represents the solidus temperature of the Class A titanium alloy materials.

[0107] The low-temperature annealing temperature of the aforementioned Class B titanium alloy materials is greater than or equal to 0.3Tb2 and less than or equal to 0.6Tb2; where Tb2 represents the solidus temperature of the Class B titanium alloy materials.

[0108] Step 103.6: Cool the third preform heated to the first temperature 4 to obtain the second preform. The cooling method includes air cooling or furnace cooling. The temperature of the third preform after cooling can be set according to the actual situation, such as room temperature.

[0109] In the solution aging strategy, steps 103.1 to 103.4 above can be defined as the solution process, and steps 103.5 and 103.6 above can be defined as the aging process.

[0110] For the double annealing strategy:

[0111] See Figure 2 and Figure 3 Step 103: Heat-treat the first preform according to the heat treatment strategy (i.e., double annealing strategy) to obtain the second preform, including:

[0112] Step 103.1: Heat the first preform to a fourth temperature 1 and hold it at the fourth temperature 1 for a fourth time period; the fourth temperature 1 is less than the lowest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials.

[0113] In one alternative approach, the high-temperature annealing temperature of the aforementioned titanium alloy material is greater than or equal to a and less than or equal to b; wherein a = recrystallization temperature of the titanium alloy material - 50℃, and b = solidus temperature of the titanium alloy material - 100℃.

[0114] For example, the first preform is heated to a fourth temperature in the furnace. The fourth temperature is greater than or equal to 500°C and less than or equal to 600°C; the fourth time period is greater than or equal to 0.5 hours and less than or equal to 1 hour. For example, the fourth temperature is 500°C, 520°C, 540°C, 550°C, 570°C, 580°C, 596°C, or 600°C, etc. The fourth time period is 0.5 hours, 0.56 hours, 0.7 hours, 0.85 hours, 0.93 hours, or 1 hour, etc. When both materials used to make the part are titanium alloys (the specific properties of titanium alloys are not specifically limited here), the high-temperature annealing temperature of the titanium alloy is greater than or equal to 750°C and less than or equal to 1000°C.

[0115] Step 103.2: Perform at least two oscillating temperature treatments on the first preform to obtain the third preform;

[0116] By employing oscillating temperature treatment, the gradient material interface can interactively grow to form a serrated interface, resulting in better interfacial bonding and improved overall mechanical properties of the third preform, thereby enhancing the overall mechanical properties of the final part. Furthermore, the number of oscillating temperature treatments performed on the first preform is selected based on the structure and wall thickness of the final part. In this embodiment, at least two oscillating temperature treatments are used, ensuring sufficient heating of the first preform, resulting in minimal deformation, low residual stress, and excellent mechanical properties.

[0117] In one optional manner, each oscillating temperature process includes:

[0118] The first preform is heated to a second temperature 2 and held at this temperature for a second time period. The second temperature is the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials. At this time, the metallurgical kinetics of grain growth can be activated through a short period of high-temperature treatment, which helps to homogenize the microstructure of the titanium alloy with a higher β-transformation temperature. For the explanation of "the second temperature is the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials," please refer to the explanation of the above solution aging strategy; it will not be repeated here.

[0119] For example, the second time period is 10 minutes. It should be noted that the starting time for the aforementioned second heat preservation time period is when the first preform changes from the fourth temperature to the second temperature. In this embodiment of the invention, the first preform, which is at the fourth temperature 1, is heated to the second temperature 2 and kept at the second temperature 2 for the second time period.

[0120] The first preform, heated to a second temperature 2, is cooled to a third temperature 3 and held at this temperature for a third time period. The third temperature is the lowest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials. At this time, the metallurgical kinetics of grain growth are suppressed, which helps reduce the risk of coarse grains in titanium alloys with lower β-transformation temperatures. For example, the third time period is 15 minutes. Regarding the phrase "the third temperature is the lowest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials," please refer to the explanation of the above solution aging strategy; it will not be repeated here.

[0121] The cooling rate at which the first preform heated to the second temperature 2 is cooled to the third temperature 3 is greater than or equal to 5℃ / min and less than or equal to 15℃ / min. For example, the cooling rate can be 5℃ / min, 8℃ / min, 9℃ / min, 10℃ / min, 13℃ / min, or 15℃ / min, etc.

[0122] The heating rate when the first preform, cooled to a third temperature 3, is heated to a second temperature 2 is greater than or equal to 10℃ / min and less than or equal to 15℃ / min. For example, the heating rate can be 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, or 15℃ / min, etc.

[0123] In one alternative approach, while the first preform heated to the second temperature 2 is kept warm for a second time period, an alternating magnetic field is applied to the space in which the region of the first preform heated to the second temperature 2 has the lowest β transition temperature.

[0124] Under the intervention of an alternating magnetic field, abnormal growth of microstructures during heating can be suppressed, and grains can be refined. For example, coarse microstructures in titanium alloys can be suppressed to optimize the performance of the first preform. Furthermore, since the region in the first preform with the lowest β-transformation temperature is prone to structural deterioration after the aforementioned series of steps, its microstructure is easily coarsened, resulting in the worst performance compared to other regions. Therefore, in this embodiment of the invention, an alternating magnetic field is not applied to all spaces containing the first preform; instead, it is applied only to the space containing the region with the lowest β-transformation temperature within the first preform.

[0125] Based on the previous description, under the dual effects of oscillating temperature treatment and alternating magnetic field strengthening, abnormal growth of microstructures during heating can be further suppressed, grains can be refined, and the overall mechanical properties of the final obtained parts can be further improved.

[0126] Step 103.3: The third preform is subjected to temperature treatment to bring its temperature to the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials (for ease of description, this is referred to as the second preset temperature 5). At this time, rapid cooling at high temperature causes quenching or solution treatment in different regions of the third preform, forming a large number of dislocations inside the material, preparing for subsequent low-temperature annealing.

[0127] For example, the first preform at the third temperature 3 is heated to the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials (i.e., the second preset temperature 5), and held at the second preset temperature 5 for a period of time. The specific holding time can be set according to actual needs and is not specifically limited here.

[0128] Step 103.4: Reduce the temperature of the third preform after temperature treatment to the preset temperature;

[0129] Since the temperature of the third preform is the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials, it is possible to accommodate the cooling temperatures of various materials so that all materials can be cooled to the preset temperature, which facilitates subsequent operations and ensures the quality and performance of the third preform.

[0130] The preset temperature can be set according to actual needs. For example, the preset temperature can be room temperature, slightly higher or lower than room temperature, as long as it meets the actual needs.

[0131] The methods mentioned above for reducing temperature include water cooling, oil cooling, or air cooling.

[0132] Step 103.5: Heat the third preform, which has been cooled to a preset temperature, to a first temperature 4, and hold it at the first temperature 4 for a first time period. The preset temperature is lower than the first temperature 4. The first temperature is the lowest of the aging temperature and / or low-temperature annealing temperature of the two titanium alloy materials. At this time, the metastable structure introduced by the high-temperature annealing process can be adjusted to reduce stress and improve toughness. The first time period is greater than or equal to 4 hours and less than or equal to 8 hours. For example, the first time period can be 4 hours, 5 hours, 6 hours, 7 hours, 7.6 hours, or 8 hours, etc.

[0133] In one alternative approach, the low-temperature annealing temperature of the titanium alloy material is greater than or equal to 0.3Tb and less than or equal to 0.6Tb; where Tb represents the solidus temperature of the titanium alloy material.

[0134] For example, when both materials used to make the part are titanium alloys (the specific properties of titanium alloys are not specifically limited here), the low-temperature annealing temperature of the titanium alloy is greater than or equal to 450°C and less than 750°C.

[0135] Regarding the phrase "the first temperature is the lowest of the aging temperatures and / or low-temperature annealing temperatures of the two titanium alloy materials," please refer to the explanation of the above solution aging strategy for this purpose, which will not be repeated here.

[0136] Step 103.6: Cool the third preform heated to the first temperature 4 to obtain the second preform. The cooling method includes air cooling or furnace cooling. The temperature of the third preform after cooling can be set according to the actual situation, such as room temperature.

[0137] In the dual annealing strategy, steps 103.1 to 103.4 above can be defined as a high-temperature annealing process, and steps 103.5 and 103.6 above can be defined as a low-temperature annealing process.

[0138] In summary, compared to existing technologies that process parts made of two materials but only use a heat treatment process for one of the materials to heat-treat the first preform, the additive manufacturing method for gradient materials provided in this invention can take both materials into account, ensuring that the performance of the final part meets actual requirements and avoiding performance issues arising from one material being sacrificed for another. Furthermore, compared to existing technologies that use compromise heat treatment processes for the first preform, this method can reduce or avoid the problems of microstructure inhomogeneity and performance instability in parts formed from one or two materials. For example, it can reduce or avoid the problems of microstructure inhomogeneity and performance instability in parts formed from high-temperature titanium alloys.

[0139] This invention also provides a computer storage medium. The computer storage medium stores instructions that, when executed, implement the additive manufacturing method for gradient materials described above.

[0140] The beneficial effects of the computer storage medium provided in this embodiment of the invention are the same as those of the additive manufacturing method for gradient materials described in the above technical solution, and will not be repeated here.

[0141] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The aforementioned computer program product includes one or more computer programs or instructions. When the aforementioned computer program or instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present invention are performed, in whole or in part. The aforementioned computer can be a general-purpose computer, a special-purpose computer, a computer network, a terminal, a user equipment, or other programmable device. The aforementioned computer program or instructions can be stored in a computer-readable storage medium, or transferred from one computer-readable storage medium to another. For example, the aforementioned computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The aforementioned computer-readable storage medium can be any available medium accessible to a computer, or a data storage device such as a server or data center integrating one or more available media. The aforementioned available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video disc (DVD); or it can be a semiconductor medium, such as a solid-state drive (SSD).

[0142] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0143] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. An additive manufacturing method for gradient materials, characterized in that, include: Two titanium alloy materials are processed using additive manufacturing to obtain a part blank; the two titanium alloy materials are formed into a gradient material. The part blank is rough machined to obtain the first preform; The first preform is heat-treated according to a heat treatment strategy to obtain the second preform; The second preform is precision machined to obtain the part; The first preform is heat-treated according to a heat treatment strategy to obtain the second preform, which includes: The first preform is subjected to at least two oscillating temperature treatments to obtain the third preform. The third preform is subjected to temperature treatment so that the temperature of the third preform is the highest among the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials. The temperature of the third preform, which has undergone temperature treatment, is reduced to a preset temperature; The third preform, which has been cooled to the preset temperature, is heated to a first temperature and held at the first temperature for a first time period; the preset temperature is lower than the first temperature. The third preform heated to the first temperature is cooled to obtain the second preform; Each of the aforementioned oscillating temperature processes includes: The first preform is heated to a second temperature and held at the second temperature for a second time period; the second temperature is the highest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials. The first preform heated to the second temperature is cooled to the third temperature and held at the third temperature for a third time period; the third temperature is the lowest of the solution temperature and / or high-temperature annealing temperature of the two titanium alloy materials. The high-temperature annealing temperature of the titanium alloy material is greater than or equal to a and less than or equal to b; wherein a = recrystallization temperature of the titanium alloy material - 50℃, and b = solidus temperature of the titanium alloy material - 100℃. While the first preform heated to the second temperature is kept warm for the second time period, an alternating magnetic field is applied to the space where the region of the first preform heated to the second temperature has the lowest β transition temperature.

2. The additive manufacturing method for gradient materials according to claim 1, characterized in that, The heat treatment strategy is either a solution aging strategy or a double annealing strategy.

3. The additive manufacturing method for gradient materials according to claim 1, characterized in that, When the heat treatment strategy is a solution aging strategy, the first temperature is the highest temperature among the aging temperature and / or low-temperature annealing temperature of the two titanium alloy materials; the first time period is greater than or equal to 4 hours and less than or equal to 12 hours. When the heat treatment strategy is a dual annealing strategy, the first temperature is the lowest of the aging temperature and / or low-temperature annealing temperature of the two titanium alloy materials; the first time period is greater than or equal to 4 hours and less than or equal to 8 hours.

4. The additive manufacturing method for gradient materials according to claim 1, characterized in that, The second time period is 10 minutes, and the third time period is 15 minutes; When the heat treatment strategy is a solution aging strategy, the cooling rate when the first preform heated to the second temperature is cooled to the third temperature is greater than or equal to 20℃ / min and less than or equal to 30℃ / min; the heating rate when the first preform cooled to the third temperature is heated to the second temperature is greater than or equal to 20℃ / min and less than or equal to 30℃ / min. When the heat treatment strategy is a double annealing strategy, the cooling rate when the first preform heated to the second temperature is cooled to the third temperature is greater than or equal to 5℃ / min and less than or equal to 15℃ / min; the heating rate when the first preform cooled to the third temperature is heated to the second temperature is greater than or equal to 10℃ / min and less than or equal to 15℃ / min.

5. The additive manufacturing method for gradient materials according to claim 3, characterized in that, The low-temperature annealing temperature of the titanium alloy material is greater than or equal to 0.3Tb and less than or equal to 0.6Tb; where Tb represents the solidus temperature of the titanium alloy material.

6. The additive manufacturing method for gradient materials according to claim 1, characterized in that, Two titanium alloy materials were processed using additive manufacturing methods to obtain part blanks, including: The two titanium alloy materials are processed by laser deposition and / or arc additive manufacturing to obtain the part blank.

7. The additive manufacturing method for gradient materials according to claim 1, characterized in that, Before rough machining the part blank, the additive manufacturing method for gradient materials further includes: stress relief treatment of the part blank.

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