Self-lubricating taper die-casting metal bar for friction stir additive manufacturing and preparation method and application thereof

Abstract

The present application relates to a kind of self-lubricating taper die-casting metal bar for friction stir additive manufacturing and its preparation method and application.The preparation steps of the bar are as follows: design corresponding high-pressure casting mold according to the structure of the bar;heat the mold, then spray release agent on the surface of the mold;Pour the molten metal into the mold, and perform die casting under high speed and high pressure, and it is obtained immediately.The present application directly forms near-net-size metal bar with preset taper by die casting, and the initial fine-grained structure obtained by high speed and high pressure of die casting can regulate the recrystallization behavior in the additive process, so as to obtain uniform and fine structure.The taper structure and self-lubricating effect can reduce the frictional resistance of the bar during feeding, reduce or avoid the use of lubricant, improve the interface bonding quality during additive process, significantly reduce material loss and cost and improve the performance of additive components.

Description

Technical Field

[0001] This invention belongs to the field of advanced manufacturing technology, specifically relating to the field of metal material forming and additive manufacturing technology, and more specifically to a self-lubricating tapered die-cast metal bar for friction stir additive manufacturing, its preparation method, and its application. Background Technology

[0002] Friction stir additive manufacturing is an additive manufacturing technology based on solid-state plastic deformation. Through the rotation and axial pressure of a stirring tool, materials undergo intense plastic flow and are deposited layer by layer. Because it achieves dense bonding at relatively low temperatures, avoiding defects that occur during melting and solidification, it has broad application prospects in the manufacture of materials such as aluminum alloys and magnesium alloys.

[0003] Currently, the raw materials used in friction stir additive manufacturing are mainly rolled plates or forged materials, which are then prepared into bars or strips by wire cutting or machining before being fed into the feed system. However, this method of raw material preparation has the following shortcomings: (1) Low material utilization. A large amount of cutting waste is generated during the preparation of bar stock by wire cutting or machining, resulting in serious material waste; (2) High manufacturing cost. The raw materials need to go through multiple processing steps, such as continuous casting, cutting, and grinding, which increases the manufacturing cycle and cost; (3) Unstable microstructure and properties. Residual stress or microstructure inhomogeneity may be introduced during processing, thereby affecting the plastic flow behavior during additive manufacturing; (4) Dimensions depend on post-processing accuracy. The consistency of raw material dimensions mainly depends on machining accuracy, making it difficult to achieve efficient batch production.

[0004] On the other hand, in friction stir additive manufacturing, the bar stock typically needs to be conveyed to the processing area through a barrel or guide channel. Under high temperature and high pressure conditions, adhesion or jamming can easily occur between the bar stock and the inner wall of the channel, thus affecting the feeding stability. Existing technologies usually introduce lubricants to reduce frictional resistance, but the use of lubricants will form a residual layer on the material surface, reducing interface cleanliness and thus affecting the metallurgical bonding quality between materials during additive manufacturing.

[0005] Therefore, how to obtain metal rods that balance feeding stability, interfacial bonding quality, and material microstructure properties during additive manufacturing while improving material utilization, reducing manufacturing costs, and shortening the manufacturing cycle has become a pressing technical problem in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a self-lubricating tapered metal bar for friction stir additive manufacturing, its preparation method and application, in order to solve the problems of low material utilization, high preparation cost, dependence on lubricant in the feeding process and limited interface bonding quality in the prior art.

[0007] To achieve this objective, this invention, in its research on friction stir additive manufacturing (FSM) bars, discovered that die-cast parts possess extremely high dimensional accuracy and stability, with exceptionally smooth surfaces (Ra value reaching 0.8~3.2 μm). FSM bars produced using die casting require no subsequent processing such as cutting or grinding and can be directly used in FSM manufacturing. Furthermore, die casting can easily form bars of various shapes required for FSM, such as circular, rectangular, or other rotationally symmetric shapes, and can form most common low-melting-point metal materials, such as aluminum alloys, magnesium alloys, zinc alloys, and copper alloys. In addition, die casting relies on pressure feeding, typically eliminating the need for large risers. The die casting gating system (such as runners, sprues, etc.) and slag can be directly remelted and recycled, resulting in high material utilization. This solves the problems of low material utilization, numerous processing steps, and high manufacturing costs in existing FSM bar manufacturing processes, achieving near-net-shape forming of FSM bars.

[0008] The die-cast bars solidify under high cooling rates and high pressures, resulting in a fine-grained structure. This fine-grained structure undergoes dynamic recrystallization during subsequent friction stir additive manufacturing. However, the initial microstructure regulates the recrystallization nucleation and grain growth processes, leading to a uniform fine-grained structure in the final deposited layer, thus improving the material's mechanical properties and microstructure stability. Although the die-cast bars may contain trace casting defects such as porosity, shrinkage cavities, and segregation, these defects are mitigated during friction stir additive manufacturing. Under the influence of the stirring head, the material undergoes vigorous plastic flow and is subjected to high axial pressure. The porosity and shrinkage cavities close and compact during this process, while the material flow and migration reduce compositional segregation, ultimately resulting in a uniform and dense component.

[0009] This invention further incorporates a tapered design in the die-casting mold for friction stir additive manufacturing (FSM) bars. This tapered structure reduces the actual contact area in the feeding channel during the subsequent FSM feeding process, thereby reducing frictional resistance and adhesion tendency, and ensuring stable feeding even under high temperature and pressure conditions. The preferred tapered angle is 0.1° to 5°. A taper that is too small is insufficient to reduce frictional resistance and adhesion tendency, while a taper that is too large results in excessive cross-sectional area differences between the two ends of the bar, leading to uneven microstructure and consequently reduced and unstable performance during the subsequent additive manufacturing process.

[0010] This invention also discovers that the release agent sprayed on the mold surface during die casting can form a self-lubricating coating on the surface of the die-cast bar. This self-lubricating coating reduces the adhesion tendency between the bar surface and the mold surface. Furthermore, because this self-lubricating coating is generated under high temperature and pressure during the molten metal filling process, it has strong adhesion to the bar surface and is thin, thus having minimal impact on the interface during subsequent friction stir additive manufacturing. This invention preferably uses a water-based release agent. Common oil-based or powder-based release agents leave significant residues on the casting surface, which can affect interfacial bonding during subsequent additive manufacturing. Furthermore, this invention specifies that magnesium alloys must use silicone-free release agents. Silicon is a common impurity in magnesium alloys, and silicone-containing release agents can cause gray-black or dark spots or streaks on the surface of magnesium alloy castings, which can also affect interfacial bonding during subsequent additive manufacturing. This invention also preferably requires the mold temperature during die casting to be above 150°C. Under this condition, the mold has sufficient temperature to quickly evaporate the moisture in the release agent during spraying, thereby improving the surface quality of the casting. The present invention further preferably uses a water-based release agent aqueous solution, which contains water and water-based release agent in a volume ratio of 1:40 to 1:200. If the content of the water-based release agent is too high, it will leave excessive residue on the casting surface, which will affect the interfacial bonding during subsequent additive manufacturing. If the content of the water-based release agent is too low, it will not achieve the effect of forming a self-lubricating coating on the casting surface. Furthermore, the present invention preferably uses a release agent spraying time of no more than 6 seconds. Excessive spraying time will result in excessive residue on the casting surface and excessive drop in mold temperature.

[0011] The tapered structure and self-lubricating coating of the self-lubricating tapered metal rod prepared by this invention can reduce or avoid the use of lubricants, significantly improve the interface cleanliness and the metallurgical bonding quality between materials during the additive manufacturing process, and thus improve the performance of additive components.

[0012] The objective of this invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for preparing a self-lubricating tapered die-cast metal bar for friction stir additive manufacturing, comprising the following steps: A1. Design the corresponding high-pressure casting mold based on the structure of the self-lubricating tapered die-casting metal bar; A2. Heat the mold, and then spray a release agent onto the surface of the mold; A3. The molten metal is injected into a mold and die-cast under high speed and high pressure to obtain the self-lubricating tapered die-cast metal bar material for friction stir additive manufacturing. In step A2, the release agent is a water-based release agent aqueous solution; the volume ratio of water to water-based release agent in the water-based release agent aqueous solution is 1:40 to 1:200.

[0013] Preferably, the self-lubricating tapered die-cast metal bar has a taper set along the axial direction, such that the cross-sectional area of ​​one end of the bar is smaller than the cross-sectional area of ​​the other end; the taper is 0.1°~5°.

[0014] Preferably, the cross-section of the self-lubricating tapered die-cast metal bar is any one of a circle, a rectangle, or other rotationally symmetric shape.

[0015] Preferably, the metal material of the self-lubricating tapered die-cast metal bar includes at least one of pure aluminum or aluminum alloy, pure magnesium or magnesium alloy, pure zinc or zinc alloy, pure copper or copper alloy, and other die-castable metals.

[0016] Preferably, the water-based release agent includes any one of a water-based silicone-free release agent and a water-based silicone-containing release agent.

[0017] Preferably, when the metal material is a magnesium alloy, the water-based release agent used is a water-based silicone-free release agent; when the metal material is an aluminum alloy, zinc alloy, or copper alloy, the water-based release agent used is a water-based silicone-free release agent or a water-based silicone-containing release agent.

[0018] Preferably, in step A2, the temperature of the mold heating is above 150 °C. More preferably, the temperature is 150-250 °C.

[0019] Preferably, in step A2, the spraying time of the release agent is no more than 6 seconds. More preferably, it is 3-6 seconds.

[0020] Preferably, in step A3, the boosting pressure used in the high-speed high-pressure process is 30~150 MPa, and the injection speed is 1~5 m / s.

[0021] This invention utilizes a release agent sprayed during the die casting process to form a self-lubricating coating on the surface of the bar stock. The tapered structure is arranged along the axial direction of the bar stock. The self-lubricating coating and the tapered structure can reduce the frictional resistance of the bar stock during the friction stirring additive feeding process, thereby reducing or avoiding the use of lubricant.

[0022] Secondly, the present invention provides a self-lubricating tapered die-cast metal bar for friction stir additive manufacturing prepared according to the aforementioned method.

[0023] Thirdly, the present invention provides an application of the aforementioned self-lubricating tapered die-cast metal rod as a metal rod for friction stir additive manufacturing in the preparation of additive components.

[0024] Fourthly, the present invention provides a method for preparing additive components based on friction stir additive manufacturing, comprising the following steps: A1. Design the corresponding high-pressure casting mold based on the structure of the self-lubricating tapered die-casting metal bar; A2. Heat the mold, and then spray a release agent onto the surface of the mold; A3. The molten metal is injected into a mold and die-cast under high speed and high pressure to obtain a self-lubricating tapered die-cast metal bar for friction stir additive manufacturing. A4. The self-lubricating tapered die-cast metal bar obtained in step A3 is subjected to friction stir additive manufacturing to obtain an additive component.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention utilizes die casting to achieve near-net-shape forming of bar stock, significantly reducing material loss caused by wire cutting and machining, improving material utilization, reducing production costs, and improving manufacturing efficiency; and controls the recrystallization process through the initial fine-grained structure obtained by die casting, and utilizes the plastic flow and pressure action in the stirring friction additive process to ultimately obtain a uniform and fine structure for the additive component, thereby improving its overall performance.

[0026] (2) The present invention utilizes the self-lubricating coating formed by the die casting release agent and the tapered structure design of the bar along the axial direction, which can reduce or avoid the use of lubricant, reduce interface contamination, and improve the bonding strength and performance of additive components. Attached Figure Description

[0027] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is an overall schematic diagram of the parts produced using the die-casting mold described in this invention.

[0028] Figure 2 This is a schematic cross-sectional view of the bar stock for the parts produced by the die-casting mold designed according to the present invention.

[0029] Figure 3 This is a photograph of the microstructure of the additive component obtained in Embodiment 1 of the present invention.

[0030] Figure 4 This is a photograph of the microstructure of the additive component obtained in Comparative Example 1 of the present invention.

[0031] Figure 5 The tensile property curves of the additive components obtained in Embodiment 1 and Comparative Example 1 of the present invention are shown. Detailed Implementation

[0032] The present invention will be described in detail below with reference to specific examples. These examples will help those skilled in the art to further understand the invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0033] The raw materials used in the following embodiments are all obtained through conventional means, and the present invention does not impose any special limitations.

[0034] The results of room temperature tensile property tests for each embodiment and comparative example of the present invention are summarized in Table 1. The room temperature tensile property tests were conducted according to the methods in GB / T 228.1-2021 "Metallic materials, tensile testing - Part 1: Room temperature test method".

[0035] Example 1 This embodiment provides a method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing, the specific steps of which are as follows: (1) Mold: Based on the shape and structure of the self-lubricating tapered die-casting metal bar required, the tapered angle along the axial direction is 1°, and the die-casting mold is designed accordingly.

[0036] (2) Die casting: Mg-6Gd alloy is selected and melted using conventional methods. The die casting mold temperature is heated to 250 ℃. Before die casting, a water-based silicone oil-free release agent aqueous solution is sprayed on the mold surface for 3 seconds (the volume ratio of water to water-based silicone oil-free release agent is 1:80, the brand of water-based silicone oil-free release agent is SL-3133B, purchased from Kentian Chem-Trend). The molten metal liquid is injected into the above mold for die casting. The injection speed is 3.5 m / s, the pressurization pressure is 90 MPa, and finally a self-lubricating tapered die-cast metal bar for friction stir additive manufacturing is obtained.

[0037] The rectangular bar obtained in this embodiment is directly subjected to friction stir additive manufacturing. No lubricant is needed to ensure stable feeding during the process. The processing parameters are: rotation speed 1000 rpm, travel speed 100 mm / min, single layer thickness 1 mm, and feed speed 10 mm / min, finally obtaining an additive component.

[0038] The mechanical properties of the obtained additive components are summarized in Table 1.

[0039] Example 2 This embodiment provides a method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing, the specific steps of which are as follows: (1) Mold: Based on the shape and structure of the required self-lubricating tapered die-casting metal bar, with an axial taper of 0.1°, a corresponding die-casting mold is designed. (2) Die casting: 7075 aluminum alloy is selected and melted using conventional methods. The die casting mold temperature is heated to 200 ℃. Before die casting, a water-based silicone oil release agent aqueous solution is sprayed on the mold surface for 4 seconds (the volume ratio of water to water-based silicone oil release agent is 1:200, and the brand of water-based silicone oil release agent is SL-7698S, purchased from Kentian Chem-Trend). The molten metal liquid is injected into the above mold for die casting. The injection speed is 1 m / s and the pressurization pressure is 30 MPa. Finally, a self-lubricating tapered die casting metal bar for friction stir additive manufacturing is obtained.

[0040] The round bar obtained in this embodiment is directly subjected to friction stir additive manufacturing. No lubricant is needed to ensure stable feeding during the process. The processing parameters are the same as in Embodiment 1, and finally, an additive component is obtained.

[0041] The mechanical properties of the obtained additive components are summarized in Table 1.

[0042] Example 3 This embodiment provides a method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing, the specific steps of which are as follows: (1) Mold: Based on the shape and structure of the required self-lubricating tapered die-casting metal bar, the taper along the axial direction is 5°, and the die-casting mold is designed accordingly.

[0043] (2) Die casting: Pure copper is selected and melted using conventional methods. The die casting mold temperature is heated to 150 °C. Before die casting, a water-based silicone oil-free release agent aqueous solution is sprayed on the mold surface for 5 seconds (the volume ratio of water to water-based silicone oil-free release agent is 1:40, and the brand of water-based silicone oil-free release agent is the same as in Example 1). The molten metal liquid is injected into the above mold for die casting. The injection speed is 2.4 m / s, and the pressurization pressure is 150 MPa. Finally, a self-lubricating tapered die casting metal rod for friction stir additive manufacturing is obtained.

[0044] The hexagonal bar obtained in this embodiment is directly subjected to friction stir additive manufacturing. No lubricant is needed to ensure stable feeding during the manufacturing process. The processing parameters are the same as in Embodiment 1, and the additive component is finally obtained.

[0045] The mechanical properties of the obtained additive components are summarized in Table 1.

[0046] Example 4 This embodiment provides a method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing, the specific steps of which are as follows: (1) Mold: Based on the shape and structure of the self-lubricating tapered die-casting metal bar required, the taper along the axial direction is 2.5°, and the die-casting mold is designed accordingly.

[0047] (2) Die casting: 6061 aluminum alloy was selected and melted using conventional methods. The die casting mold temperature was heated to 220 ℃. Before die casting, a 6-second water-based silicone oil-free release agent aqueous solution was sprayed on the mold surface (the volume ratio of water to water-based silicone oil-free release agent was 1:120, and the grade of water-based silicone oil-free release agent was the same as in Example 1). The molten metal liquid was injected into the above mold for die casting. The injection speed was 5 m / s and the pressurization pressure was 120 MPa. Finally, a self-lubricating tapered die casting metal bar for friction stir additive manufacturing was obtained.

[0048] The pentagonal bar obtained in this embodiment is directly subjected to friction stir additive manufacturing. No lubricant is needed during the manufacturing process to ensure stable feeding. The processing parameters are the same as in Embodiment 1, and the additive component is finally obtained.

[0049] The mechanical properties of the obtained additive components are summarized in Table 1.

[0050] Comparative Example 1 This comparative example provides a method for preparing metal rods using friction stir additive manufacturing. A Mg-6Gd alloy is selected, and the metal rods are produced through semi-continuous casting, wire cutting, and grinding. The specific steps are as follows: (1) Semi-continuous casting: Weigh the raw materials according to the designed alloy composition, and after melting and refining, carry out semi-continuous casting to obtain Mg-6Gd alloy ingots; (2) Wire cutting: After homogenization heat treatment, the Mg-6Gd alloy ingot obtained in step (1) is cut along the ingot axis by wire cutting to obtain a bar blank of a predetermined size. The size of the bar blank is 0.5 mm larger than the target size. (3) Grinding process: The bar blank obtained in step (2) is subjected to rough grinding and fine grinding in sequence to remove the surface oxide scale and wire cutting marks, so that the surface roughness Ra ≤ 3.2 μm, and finally a metal bar that can be used for friction stir additive manufacturing is obtained.

[0051] The rectangular bar (without taper) obtained in this comparative example was subjected to friction stir additive manufacturing. Lubricant was required during friction stir additive manufacturing to ensure stable feeding (if no lubricant was added, the bar would get stuck during friction stir additive manufacturing, and a complete additive component could not be obtained). The processing parameters were the same as in Example 1, and an additive component was finally obtained.

[0052] The mechanical properties of the obtained additive components are summarized in Table 1.

[0053] Comparative Example 2 This comparative example provides a method for preparing metal rods using friction stir additive manufacturing. The method uses 7075 aluminum alloy and produces metal rods by semi-continuous casting + wire cutting + grinding. The specific steps are the same as those in Comparative Example 1.

[0054] The round bar stock (without taper) obtained in this comparative example was subjected to friction stir additive manufacturing. Lubricant was required during friction stir additive manufacturing to ensure stable feeding (if no lubricant was added, the bar stock would get stuck during friction stir additive manufacturing, and a complete additive component could not be obtained). The processing parameters were the same as in Example 1, and an additive component was finally obtained.

[0055] The mechanical properties of the obtained additive components are summarized in Table 1.

[0056] Comparative Example 3 This comparative example provides a method for preparing metal rods by friction stir additive manufacturing, which is basically the same as the method in Example 1, except that in the die casting step of this comparative example, a water-based silicone oil release agent (the same type as in Example 2) is used instead of a water-based silicone oil-free release agent.

[0057] The rectangular bar obtained in this comparative example was directly subjected to friction stir additive manufacturing. No lubricant was needed to ensure stable feeding during the process. The processing parameters were the same as in Example 1, and the additive component was finally obtained.

[0058] The mechanical properties of the obtained additive components are summarized in Table 1.

[0059] Comparative Example 4 This comparative example provides a method for preparing metal rods by friction stir additive manufacturing, which is basically the same as the method in Example 2, except that in the die casting step of this comparative example, an oil-based release agent (brand name: Yoko Advanced Release Oil S303, purchased from Yoko Petrochemical Co., Ltd.) is used instead of the aqueous solution of water-based silicone oil release agent.

[0060] The round bar obtained in this comparative example was directly subjected to friction stir additive manufacturing. No lubricant was needed to ensure stable feeding during the process. The processing parameters were the same as in Example 1, and the additive component was finally obtained.

[0061] The mechanical properties of the obtained additive components are summarized in Table 1.

[0062] Comparative Example 5 This comparative example provides a method for preparing metal rods by friction stir additive manufacturing, which is basically the same as the method in Example 3, except that the mold temperature is heated to 130 ℃ in the die casting step of this comparative example.

[0063] The hexagonal bar obtained in this comparative example was directly subjected to friction stir additive manufacturing. No lubricant was needed to ensure stable feeding during the process. The processing parameters were the same as in Example 1, and the additive component was finally obtained.

[0064] The mechanical properties of the obtained additive components are summarized in Table 1.

[0065] Comparative Example 6 This comparative example provides a method for preparing metal rods by friction stir additive manufacturing, which is basically the same as the method in Example 4, except that in the die casting step of this comparative example, the same water-based silicone-free release agent aqueous solution as in Example 4 is sprayed for 7 seconds.

[0066] The pentagonal bar obtained in this comparative example was directly subjected to friction stir additive manufacturing. No lubricant was needed to ensure stable feeding during the process. The processing parameters were the same as in Example 1, and the additive component was finally obtained.

[0067] The mechanical properties of the obtained additive components are summarized in Table 1.

[0068] Comparative Example 7 This comparative example provides a method for preparing metal rods by friction stir additive manufacturing, which is basically the same as the method in Example 3, except that in the die casting step of this comparative example, the volume ratio of the water-based silicone oil-free release agent aqueous solution to the sprayed water-based silicone oil-free release agent aqueous solution is 1:30.

[0069] The hexagonal bar obtained in this comparative example was directly subjected to friction stir additive manufacturing. No lubricant was needed to ensure stable feeding during the process. The processing parameters were the same as in Example 1, and the additive component was finally obtained.

[0070] The mechanical properties of the obtained additive components are summarized in Table 1.

[0071] Comparative Example 8 This comparative example provides a method for preparing metal rods by friction stir additive manufacturing, which is basically the same as the method in Example 2, except that in the die casting step of this comparative example, the volume ratio of water to water-based silicone oil release agent in the sprayed aqueous solution is 1:220.

[0072] Because the release agent concentration was too low, an effective self-lubricating coating could not be formed, and no lubricant was added, the bar stock prepared in this comparative example got stuck when directly subjected to the same friction stir additive manufacturing process as in Example 2, and no complete additive component was obtained.

[0073] Comparative Example 9 This comparative example provides a method for preparing metal rods by friction stir additive manufacturing, which is basically the same as the method in Example 3. The only difference is that in step (1) of this comparative example, the taper of the self-lubricating tapered die-cast metal rod is set along the axial direction as 6°, and the die-casting mold is designed accordingly.

[0074] The hexagonal bar obtained in this comparative example was directly subjected to the same friction stir additive manufacturing process as in Example 3. Due to the excessive taper, the bar was finer in the first pass and coarser in the second pass during friction stir additive manufacturing, resulting in interface separation and failure to obtain a complete additive component.

[0075] Comparative Example 10 This comparative example provides a method for preparing metal rods by friction stir additive manufacturing, which is basically the same as the method in Example 2. The only difference is that in step (1) of this comparative example, the taper of the self-lubricating tapered die-cast metal rod is set to 0° along the axial direction, and the die-casting mold is designed accordingly.

[0076] The round bar obtained in this comparative example was directly subjected to the same friction stir additive manufacturing process as in Example 2. Due to the lack of taper, the bar got stuck during friction stir additive manufacturing, and no complete additive component was obtained.

[0077] Figure 1 This is a schematic diagram of the overall structure of the parts produced using the die-casting mold described in this invention. It mainly includes a bar stock (i.e., a self-lubricating tapered die-casting bar stock), a sprue, a sprue, and a slag bag. After cutting the produced parts, self-lubricating tapered die-casting metal bars suitable for friction stir additive manufacturing can be obtained.

[0078] Figure 2 This is a schematic diagram of the cross-section of the bar stock of the part produced by the die-casting mold designed according to the present invention. It can be seen from the diagram that by designing the corresponding die-casting mold, the cross-section of the self-lubricating tapered die-casting metal bar stock can be circular, rectangular, pentagonal, hexagonal, or other rotationally symmetric shapes.

[0079] Figure 3 These are micrographs of the additive manufacturing components obtained in Embodiment 1 of the present invention. Figure 3 It can be seen that the component structure undergoes dynamic recrystallization, forming a refined and uniform grain structure with an average grain size of about 2.5 μm; and no defects such as porosity, shrinkage cavities, or segregation were found in the structure, thus achieving effective control of die casting defects.

[0080] Figure 4 The image shows the microstructure of the additive component obtained in Comparative Example 1 of this invention. Figure 4It can be seen that only part of the component structure underwent dynamic recrystallization, forming a fine-grained structure, while some grains still maintained a coarse morphology, with an average grain size of about 6.1 μm, which is much higher than that of Example 1.

[0081] Figure 5 The figures show the tensile properties of the additive components of Example 1 and Comparative Example 1 of the present invention. It can be seen that the yield strength, tensile strength and elongation of the additive component obtained in Example 1 are much higher than those in Comparative Example 1.

[0082] Table 1 below shows the room temperature tensile properties test results of various embodiments and comparative examples of the present invention.

[0083] As shown in Table 1, the die-cast metal rods obtained by this invention, after friction stir additive manufacturing, produce additive components with superior yield strength, tensile strength, and elongation compared to those obtained from traditional metal rods. Furthermore, the die-cast metal rods obtained by this invention possess self-lubricating and tapered structures, enabling stable and continuous feeding without the use of lubricants during the additive manufacturing process; no significant jamming or adhesion phenomena were observed.

[0084] In Comparative Example 3, a silicone-containing release agent was used in the magnesium alloy, and its mechanical properties were significantly reduced compared to Example 1.

[0085] Comparative Example 4 used an oil-based release agent, and its mechanical properties were significantly reduced compared to Example 2.

[0086] In Comparative Example 5, the mold temperature was insufficient, resulting in a significant decrease in its mechanical properties compared to Example 3.

[0087] In Comparative Example 6, the release agent was sprayed for too long, resulting in a significant decrease in its mechanical properties compared to Example 4.

[0088] In Comparative Example 7, the concentration of the release agent was too high, and its mechanical properties were significantly reduced compared to Example 3.

[0089] Therefore, the results show that the bar stock prepared by the method of the present invention can effectively control die casting defects while ensuring feeding stability and obtain a uniform and refined microstructure, thereby improving the overall performance of additive components.

[0090] Table 1 The above description of the embodiments is provided to enable those skilled in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing, characterized in that, Includes the following steps: A1. Design the corresponding high-pressure casting mold based on the structure of the self-lubricating tapered die-casting metal bar; A2. Heat the mold, and then spray a release agent onto the surface of the mold; A3. The molten metal is injected into a mold and die-cast under high speed and high pressure to obtain the self-lubricating tapered die-cast metal bar material for friction stir additive manufacturing. In step A2, the release agent is a water-based release agent aqueous solution; the volume ratio of water to water-based release agent in the water-based release agent aqueous solution is 1:40 to 1:

200.

2. The method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing according to claim 1, characterized in that, The self-lubricating tapered die-cast metal bar has a taper set along the axial direction; the taper is 0.1°~5°.

3. The method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing according to claim 1 or 2, characterized in that, The cross-section of the self-lubricating tapered die-cast metal bar is any one of a circle, a rectangle, or other rotationally symmetric shape.

4. The method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing according to claim 1 or 2, characterized in that, The metal material of the self-lubricating tapered die-cast metal bar includes at least one of pure aluminum or aluminum alloy, pure magnesium or magnesium alloy, pure zinc or zinc alloy, pure copper or copper alloy, and other die-castable metals. The water-based release agent includes any one of a water-based silicone-free release agent and a water-based silicone-containing release agent; When the metal material is pure magnesium or magnesium alloy, the water-based release agent used is a water-based silicone-free release agent; when the metal material is pure aluminum or aluminum alloy, pure zinc or zinc alloy, pure copper or copper alloy, or other die-castable metals, the water-based release agent used is a water-based silicone-free release agent or a water-based silicone-containing release agent.

5. The method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing according to claim 1, characterized in that, In step A2, the temperature of the mold heating is above 150 ℃.

6. The method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing according to claim 1, characterized in that, In step A2, the spraying time of the release agent shall not exceed 6 seconds.

7. The method for preparing self-lubricating tapered die-cast metal bars for friction stir additive manufacturing according to claim 1, characterized in that, In step A3, the boosting pressure used in the high-speed high-pressure process is 30~150 MPa, and the injection speed is 1~5 m / s.

8. A self-lubricating tapered die-cast metal bar for friction stir additive manufacturing prepared according to any one of claims 1-7.

9. The application of the self-lubricating tapered die-cast metal rod according to claim 8 as a metal rod for friction stir additive manufacturing in the preparation of additive components.

10. A method for preparing additive components based on friction stir additive manufacturing, characterized in that, The process includes the following steps: subjecting the self-lubricating tapered die-cast metal rod prepared by the method described in claims 1-7 or the self-lubricating tapered die-cast metal rod described in claim 8 to friction stir additive manufacturing to obtain an additive component.

Images