Method for producing a friction stir processed modified layer

Abstract

The application discloses a preparation method of a modified layer by friction stir processing, and the preparation method comprises the following steps: firstly, a first powder material is paved on the upper surface of a processed material, and a friction stir processing tool with set friction stir processing parameters is used to process the processed material, so that the cracking defects are actively controlled to form; secondly, the second powder material is filled on the upper surface of the cracking defects, and a friction stir processing tool with controlled process parameters is used to process the processed material and the first powder material, so that the cracking defects are eliminated; and the above steps are repeated for k times until k=n, so that the formed tissue contains a modified material, and a modified layer is formed. By using the existing friction stir welding equipment, all preparation processes of the modified layer can be completed, more equipment does not need to be invested, the production cost can be reduced, the preparation steps of the modified layer are simplified, and the practicability of the modified layer prepared by the friction stir processing is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of friction stir processing technology, and in particular to a method for preparing a friction stir modified layer. Background Technology

[0002] Friction stir welding (FSW) is a solid-state welding technology, particularly suitable for materials such as aluminum alloys, magnesium alloys, and copper alloys that are difficult to weld using hot-melt welding methods (e.g., laser welding, electron beam welding, and TIG welding). Friction stir processing (FSP) evolved from FSW technology and aims to use the principles of FSW to modify the surface of raw materials, thereby improving their service performance to meet more demanding engineering requirements.

[0003] Using powder particles as the main material for modification and reinforcement, and employing FSP technology to prepare modified layers on materials such as aluminum alloys, the methods are mainly divided into two categories: the drilling reconstruction method and the pre-layer reconstruction method. The pre-layer reconstruction method involves first coating a pre-layer onto the substrate surface using methods such as spraying, and then processing it using FSP technology to achieve microstructure and property control. The drilling reconstruction method involves first drilling holes in the substrate surface, then filling the pores with powder, and finally processing it using FSP technology to ensure thorough mixing of the powder and substrate to form a coating. Although preparing modified layers on the surface of materials such as aluminum alloys using drilling FSP and pre-layer FSP processes is feasible, both are only applied in certain specific fields and have relatively limited application in the overall engineering industry. These methods consistently face challenges and limitations in large-scale application, such as the drilling process and the preparation of the pre-layer, which significantly increase the complexity and cost (mainly due to additional equipment investment and operator learning costs).

[0004] Compared to pre-formed layers, the drilling reconstruction method yields a deeper and more uniform modified layer. This is because the depth of the modified layer is only affected by the length of the stirring head of the friction stir tool, and the amount and distribution of the injected modified material can be adjusted according to the initial drilling conditions (e.g., hole diameter, hole depth, number of holes, and hole location distribution). The pre-formed reconstruction method, due to the inherent cutting effect during the friction stir process, can compromise the integrity of the pre-formed layer, affecting the thickness and performance of the final coating. Therefore, the drilling reconstruction method provides better mechanical support, is more conducive to preserving the original coating and achieving better results, and is beneficial to the stability and quality of the modified layer.

[0005] By simplifying the process of preparing surface-modified layers for materials such as aluminum alloys using perforated FSP (Friction Stir Welding), and shortening the preparation process and operational steps, the engineering application scenarios of FSP surface modification technology can be significantly broadened, making it more practical. In the FSP process, a type of weld breakage and cracking often occurs, commonly seen in the welding of dissimilar materials, and is known as tool path cracking. Welding dissimilar materials is one of the most common causes of cracking defects. Introducing this weld breakage and cracking defect structure to replace the pre-process steps of perforated FSP allows a single friction stir welding machine to complete the entire process of surface-modified layer preparation, significantly improving industrial processing efficiency and making the FSP surface-modified layer preparation process truly practical. Summary of the Invention

[0006] The technical problem to be solved by this invention is that the existing friction stir processing technology for preparing surface modification layers of materials such as aluminum alloys is complex and costly, thus preventing its large-scale application. This invention provides a method for preparing friction stir modified layers, which uses only existing friction stir welding equipment to complete all the preparation steps of the modified layer, thereby greatly improving the practicality of friction stir processing for preparing modified layers.

[0007] The technical solution adopted by this invention to solve its technical problem is: a method for preparing a stir friction processing modified layer, comprising: A modified layer is prepared on the upper surface of the material being processed by modifying powder. The modified layer includes n layers of first powder material and n layers of second powder material, which are alternately arranged from bottom to top on the upper surface of the material being processed. The method for preparing the modified layer includes the following steps: S1. The first powder material is first laid on the upper surface of the material to be processed, and the friction stir welding tool with set friction stir welding tool parameters is used to perform friction stir welding on the material to be processed, so that cracking defects are actively controlled and shaped. S2. The second powder material is first injected and filled into the upper surface of the crack defect, and the friction stir welding tool with controlled process parameters is used to perform friction stir processing on the workpiece, the first powder material and the second powder material to eliminate the crack defect. S3, repeat steps S1 and S2 above for n-1 times until the modified layer comprising n layers of first powder material and second powder material is formed, wherein: n≥1; Where: n≥1, k is the number of times the current paving and grouting are performed.

[0008] Therefore, all the preparation processes of the modified layer can be completed using existing friction stir welding equipment without investing in more equipment. This reduces production costs, simplifies the preparation steps of the modified layer, and greatly improves the practicality of friction stir processing for preparing modified layers, enabling the widespread use of friction stir processing for preparing modified layers.

[0009] Further, in step S1, setting the friction stir processing parameters of the friction stir welding tool includes: the rotational speed parameter of the second powder material and the feed rate parameter of the second powder material.

[0010] Furthermore, the rotational speed of the friction stir welding tool is 800 rpm-1500 rpm, and the feed rate of the friction stir welding tool is 20 mm / min-100 mm / min. Therefore, the friction stir welding tool has a slow rotational speed and a fast feed rate, resulting in poor welding performance.

[0011] Further, in step S2, the process parameters include: preheating the material to be processed, the rotational speed of the friction stir welding tool, the feed speed of the friction stir welding tool, changing the friction stir welding tool, and changing the feed path of the friction stir welding tool.

[0012] Furthermore, the first powder material is any one of tungsten carbide, alumina, copper, and nickel, and the second powder material is any one of tungsten carbide, alumina, copper, and nickel.

[0013] Furthermore, the material of the first powder material may be the same as or different from the material of the second powder material.

[0014] Furthermore, the material being processed is any one of aluminum alloy, magnesium alloy, copper alloy, and titanium alloy.

[0015] Furthermore, the cracking defects include: tissue pores, surface grooves, surface cracks, or tunnel defects.

[0016] Furthermore, in step S1, the paving method includes: carrier paving, room temperature paving, high temperature paving, or chemical paving.

[0017] Compared with the prior art, the beneficial effects of the present invention are: All preparation processes of the modified layer can be completed using existing friction stir welding equipment without investing in more equipment. This reduces production costs, simplifies the preparation steps of the modified layer, and greatly improves the practicality of friction stir processing for preparing modified layers, enabling the widespread use of friction stir processing for preparing modified layers. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Figure 1 This is a flowchart of the method for preparing the friction stir modified layer of the present invention; Figure 2 This is a flowchart of the preparation method of the friction stir modified layer in Example 1; Figure 3 This is a schematic diagram of the process operation flow of Example 1; Figure 4 Comparison of cracking defects in ordinary 7075 aluminum alloy sheet and 7075 aluminum alloy sheet with binder-modified powder. Figure 5 This is a comparison diagram of the commonly used drilling, powder filling, stirring, and friction processing method in Example 1 and the operation method in Example 1; Figure 6 This is a flowchart of the preparation method of the friction stir modified layer in Example 2; Figure 7 This is a flowchart of the preparation method of the friction stir modified layer in Example 3.

[0020] In the figure: 1. Material to be processed; 2. Modified layer; 3. First powder material; 4. Second powder material; 5. Friction stir welding tool; 6. Crack defect. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the 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, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0023] 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Example 1: like Figures 1 to 5 As shown, a method for preparing a friction stir modified layer includes: A modified layer 2 is prepared on the upper surface of the material being processed 1 by modifying powder. The modified layer 2 includes a first powder material 3 and a second powder material 4. The first powder material 3 and the second powder material 4 are alternately arranged from bottom to top on the upper surface of the material being processed 1. The preparation method of modified layer 2 includes the following steps: S1. First powder material 3 is first laid on the upper surface of the material to be processed 1, and the friction stir welding tool 5 with set friction stir welding parameters is used to perform friction stir welding on the material to be processed, so that the cracking defect 6 is actively controlled and shaped. S2. A second powder material 4 is first injected and filled into the upper surface of the crack defect 6. Then, a friction stir welding tool 5 with controlled process parameters is used to perform friction stir processing on the workpiece material 1, the first powder material 3, and the second powder material 4, eliminating the crack defect 6 and forming a structure containing the modified material, thus forming the modified layer 2. Therefore, all the preparation steps of the modified layer 2 can be completed using existing friction stir welding equipment without investing in more equipment. This reduces production costs, simplifies the preparation steps of the modified layer 2, and significantly improves the practicality of friction stir processing for preparing the modified layer 2, enabling its widespread application.

[0025] Specifically, the two-stage preparation method involves one paving and one injection filling (i.e., two preparation processes).

[0026] Specifically, in step S1, the processed material 1 is different from the first powder material 3, which can promote the formation of crack defects.

[0027] In this embodiment, in step S1, the parameters for friction stir welding of the tool 5 include: the rotational speed of the tool 5 and the feed rate of the tool 5; the rotational speed of the tool 5 is 800 rpm-1500 rpm, and the feed rate of the tool 5 is 20 mm / min-100 mm / min. Therefore, the slow rotational speed and fast feed rate of the tool 5 result in poor welding performance.

[0028] Specifically, under identical friction stir welding tool 5 and process parameters (the rotation speed of the friction stir welding tool 5 is 1200 rpm, and the feed rate of the friction stir welding tool 5 is 60 mm / min), ordinary 7075 aluminum alloy sheets can obtain a smooth and dense structure after processing, while 7075 aluminum alloy sheets with binder-coated modified powder are more prone to cracking along the processing path; for 7075-T6 aluminum alloy sheets subjected to friction stir welding, when the rotation speed of the friction stir welding tool 5 is reduced (from 1200 rpm to 750 rpm) and the feed rate is increased (from 60 mm / min to 100 mm / min), no pits, point cracks, or tunnel cracks appear macroscopically on the surface of the material.

[0029] In this embodiment, the process parameters include: preheating the material to be processed 1, the rotational speed of the friction stir welding tool 5, the feed rate of the friction stir welding tool 5, changing the friction stir welding tool 5, and the feed path for changing the friction stir welding tool 5. For example, the feed path of the friction stir welding tool 5 adopts a Z-shaped feed path.

[0030] In this embodiment, the first powder material 3 is any one of tungsten carbide, alumina, copper, and nickel, and the second powder material 4 is any one of tungsten carbide, alumina, copper, and nickel. The materials of the first powder material 3 and the second powder material 4 may be the same or different. Specifically, the first powder material 3 and the second powder material 4 are service performance enhancement materials.

[0031] In this embodiment, the processed material 1 is any one of aluminum alloy, magnesium alloy, copper alloy, and titanium alloy; the cracking defect 6 includes: tissue pores, surface grooves, surface cracks, and tunnel defects; the paving method includes: carrier paving, room temperature paving, high temperature paving, and chemical paving. Specifically, the platform of the cracking defect 6 is changed according to the characteristics of the first powder material 3, for example, the type of the first powder material 3, particle size, and the amount of material introduced per unit time.

[0032] Example 2: like Figure 6 As shown, the difference from Embodiment 1 is that it includes: A modified layer 2 is prepared on the upper surface of the material being processed 1 by modifying powder. The modified layer 2 includes two layers of first powder material 3 and two layers of second powder material 4, which are alternately arranged from bottom to top on the upper surface of the material being processed 1. The preparation method of modified layer 2 includes the following steps: S1. First powder material 3 is first laid on the upper surface of the material to be processed 1, and the friction stir welding tool 5 with set friction stir welding parameters is used to perform friction stir welding on the material to be processed, so that the cracking defect 6 is actively controlled and shaped. S2. First, fill the upper surface of the crack defect 6 with the second powder material 4, and use the friction stir welding tool 5 with controlled process parameters to perform friction stir processing on the workpiece material 1, the first powder material 3 and the second powder material 4, so that the crack defect 6 is eliminated. S3. The first powder material 3 is laid on the upper surface of the material to be processed 1 for the second time, and the friction stir welding tool 5 with the set friction stir welding tool 5 stirring friction processing parameters is used to stir and friction process the material to be processed, so that the cracking defect 6 is actively controlled and shaped. S4. A second layer of powder material 4 is injected and filled onto the upper surface of the crack defect 6. A friction stir welding tool 5 with controlled process parameters is used to perform friction stir processing on the workpiece material 1, the first powder material 3, and the second powder material 4, thereby eliminating the crack defect 6 and forming a structure containing the modified material, thus forming the modified layer 2. Therefore, the second powder material 4 injected and filled in the two instances is different, resulting in the modified layer 2 of Example 2 having different characteristics than the modified layer 2 of Example 1 (i.e., Example 2 has an additional characteristic compared to Example 1).

[0033] Specifically, the preparation method involves two paving steps and two injection filling steps, which constitutes a three-stage preparation process (i.e., three preparation steps).

[0034] Example 3: like Figure 7 As shown, the difference from Embodiment 1 is that it includes: A modified layer 2 is prepared on the upper surface of the material being processed 1 by modifying powder. The modified layer 2 includes three layers of first powder material 3 and three layers of second powder material 4, which are alternately arranged from bottom to top on the upper surface of the material being processed 1. The preparation method of modified layer 2 includes the following steps: S1. First powder material 3 is first laid on the upper surface of the material to be processed 1, and the friction stir welding tool 5 with set friction stir welding parameters is used to perform friction stir welding on the material to be processed, so that the cracking defect 6 is actively controlled and shaped. S2. First, fill the upper surface of the crack defect 6 with the second powder material 4, and use the friction stir welding tool 5 with controlled process parameters to perform friction stir processing on the workpiece material 1, the first powder material 3 and the second powder material 4, so that the crack defect 6 is eliminated. S3. First powder material 3 is first laid on the upper surface of the material to be processed 1, and the friction stir welding tool 5 with set friction stir welding parameters is used to perform friction stir welding on the material to be processed, so that the cracking defect 6 is actively controlled and shaped. S4. First, fill the upper surface of the crack defect 6 with the second powder material 4, and use the friction stir welding tool 5 with controlled process parameters to perform friction stir processing on the workpiece material 1, the first powder material 3 and the second powder material 4, so that the crack defect 6 is eliminated. S5. First powder material 3 is first laid on the upper surface of the material to be processed 1, and the material to be processed is subjected to friction stirring processing by the friction stirring welding tool 5 with the set friction stirring processing parameters, so that the cracking defect 6 is actively controlled and shaped. S6. The second powder material 4 is first injected and filled into the upper surface of the crack defect 6, and the workpiece material 1, the first powder material 3 and the second powder material 4 are subjected to friction stirring processing using a friction stirring tool 5 with controlled process parameters, so that the crack defect 6 is eliminated, and the structure containing the modified material is formed, forming the modified layer 2. As a result, the second powder material 4 is different in the three injections and fillings, so that the characteristics of the modified layer 2 in Example 3 are different from those in Example 1 (that is, compared with Example 1, Example 3 has two additional characteristics).

[0035] Specifically, the preparation method involves three paving steps and three injection filling steps, which constitutes a four-step preparation process (i.e., four preparation steps).

[0036] In summary, this invention can complete all the preparation steps of the modified layer 2 using existing friction stir welding equipment without investing in more equipment. This reduces production costs, simplifies the preparation steps of the modified layer 2, and greatly improves the practicality of friction stir processing for preparing the modified layer 2, enabling the widespread use of friction stir processing for preparing the modified layer 2.

[0037] The above description is based on the preferred embodiments of the present invention. Through the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the contents of the specification, but must be determined by the scope of the claims.

Claims

1. A method for preparing a friction stir modified layer, characterized in that, include: A modified layer (2) is prepared on the upper surface of the material to be processed (1) by modifying powder. The modified layer (2) includes: n layers of first powder material (3) and n layers of second powder material (4). The n layers of first powder material (3) and n layers of second powder material (4) are alternately arranged from bottom to top on the upper surface of the material to be processed (1). The method for preparing the modified layer (2) includes the following steps: S1. The first powder material (3) is first laid on the upper surface of the material to be processed (1), and the friction stir welding tool (5) with the set friction stir welding tool (5) is used to perform friction stir processing on the material to be processed (1), so that the cracking defect (6) is actively controlled and shaped. S2. The second powder material (4) is injected and filled into the upper surface of the crack defect (6) for the first time, and the friction stir welding tool (5) with controlled process parameters is used to perform friction stir processing on the workpiece (1), the first powder material (3) and the second powder material (4) so ​​that the crack defect (6) is eliminated. S3, repeat steps S1 and S2 above for n-1 times until the modified layer (2) comprising n layers of first powder material and second powder material is formed, wherein: n≥1; The first powder material (3) is any one of tungsten carbide, aluminum oxide, copper and nickel, and the second powder material (4) is any one of tungsten carbide, aluminum oxide, copper and nickel; The material to be processed (1) is any one of aluminum alloy, magnesium alloy, copper alloy and titanium alloy.

2. The method for preparing the friction stir modified layer according to claim 1, characterized in that, In step S1, setting the friction stir welding tool (5) parameters includes: The rotational speed parameters and feed rate parameters of the friction stir welding tool (5).

3. The method for preparing the friction stir modified layer according to claim 2, characterized in that, In step S1, the rotational speed of the friction stir welding tool (5) is 800 rpm-1500 rpm, and the feed rate of the friction stir welding tool (5) is 20 mm / min-100 mm / min.

4. The method for preparing the friction stir modified layer according to claim 1, characterized in that, In step S2, the process parameters include: the rotational speed of the friction stir welding tool (5), the feed speed of the friction stir welding tool (5), and the feed path for changing the friction stir welding tool (5).

5. The method for preparing the friction stir modified layer according to claim 1, characterized in that, The material of the first powder material (3) may be the same as or different from the material of the second powder material (4).

6. The method for preparing the friction stir modified layer according to claim 1, characterized in that, The cracking defects (6) include: tissue pores, surface grooves, surface cracks or tunnel defects.

7. The method for preparing the friction stir modified layer according to claim 1, characterized in that, In step S1, the paving method includes: carrier paving, room temperature paving, high temperature paving, or chemical paving.

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