Eddy stirring friction modification method and device

Abstract

The invention relates to the technical field of metal surface modification, and discloses an eddy stirring friction modification method and a modification device. A stirring rod identical to a to-be-modified workpiece and a sleeve-shaped reinforcing material sleeving the stirring rod are used as stirring tools to rub with the workpiece, and plastic eddy is induced to be generated in the workpiece; and the reinforced material is gradually expanded into a heat-flow coupling area, the reinforced material and the material of the to-be-modified workpiece are subjected to a sufficient metallurgical reaction under the heat-flow coupling action of the plastic vortex, and the reinforced material is transited into the material of the to-be-modified workpiece in modes of decomposition, replacement reaction, synthesis, solid solution, diffusion and the like, so that reaction products such as a reinforced phase or a solid solution and the like are formed. And uniformly mixing the reaction product with the to-be-modified workpiece material under the stirring action of the vortex to generate a composite material modified layer, and distributing the composite material modified layer on the upper surface of the to-be-modified workpiece. The generated modified layer can obviously improve the hardness and wear resistance of the metal surface, and the service life of a metal component is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface modification, and relates to an eddy current stir friction modification method and a modification device. Background Art

[0002] Friction stir processing (FSP), a solid-state processing technique for microstructure manipulation, is environmentally friendly and resource-efficient. The intense plastic deformation and frictional heat introduced during processing induce dynamic recrystallization, resulting in the formation of fine, equiaxed grains. FSP has been shown to effectively refine aluminum-, magnesium-, and titanium-based alloys. However, the grain refinement and equiaxed grain size achieved solely through FSP are limited in improving the wear and corrosion resistance of the material. Introducing other strengthening elements through FSP has proven to be a more effective method for improving material properties. Chinese invention patent CN106282637B proposes a method for in-situ preparation of a boron-containing magnesium-based composite. The core process involves grooving the workpiece to be modified, powder filling, and FSP. The resulting composite exhibits significantly enhanced mechanical properties compared to the unmodified magnesium alloy. Chinese invention patent CN113199027B proposes a nano-Al4C3-reinforced aluminum-based composite and its preparation method. The core process involves composite plate preparation and FSP. After FSP treatment, the material strength is improved while still retaining excellent plasticity. The above two patents both prove that the introduction of other strengthening elements through FSP technology has great potential in metal modification, but it should be noted that the core steps of the above patents either require the preparation of powder filling grooves on the workpiece to be modified in advance, or require the pre-preparation of composite materials. These processes will undoubtedly greatly weaken the modification efficiency. In addition, when selecting cemented carbide and ceramic materials such as WC, TiC, SiC and Al2O3 as strengthening elements for FSP, these high-hardness materials will cause severe friction with the stir friction tool, resulting in tool wear, thereby shortening the service time, which will undoubtedly further increase the FSP processing cost. In view of this, it is urgent to develop an FSP method that is efficient, low-cost, and compatible with multiple materials. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the present invention provides an eddy current stir friction modification method and modification device. The generated modified layer can significantly improve the hardness and wear resistance of the metal surface and increase the service life of the metal components.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] In one aspect, the present invention proposes an eddy current stir friction modification method, which utilizes a stirring rod made of the same material as the workpiece to be modified and a sleeve-shaped reinforcing material sleeved on the outside of the stirring rod as a stirring tool to rub against the workpiece to be modified, inducing the generation of plastic eddy currents within the workpiece to be modified, which gradually expands into a heat-fluid coupling region; under the heat-fluid coupling effect of the plastic eddy current, the sleeve-shaped reinforcing material undergoes a metallurgical reaction with the workpiece to be modified, transitioning into the workpiece to be modified through decomposition, displacement reaction, synthesis, solid solution, and diffusion, forming reaction products such as a reinforcing phase or solid solution; under the stirring action of the eddy current, the reaction products are uniformly mixed with the material of the workpiece to be modified to form a composite material modified layer distributed on the upper surface of the workpiece to be modified. The modified layer generated by this eddy current stir friction action can significantly improve the surface hardness and wear resistance of the workpiece, thereby increasing the service life of the workpiece.

[0006] In combination with the first aspect, further, the eddy current stir friction modification method proposed in the present invention comprises the following steps:

[0007] The sleeve-shaped reinforcement material is loaded into the clamping device to obtain an assembled device;

[0008] Fixing the combined device to the friction stir welding machine;

[0009] The stirring rod is installed into the combined device to obtain a modified device;

[0010] 99.99% argon is introduced as a shielding gas, and the modification device is rotated and pressed downward using a set program, ensuring that the bottom end of the sleeve-shaped reinforcement material is pressed into the workpiece to be modified by 0-0.2 mm. The modification device is held for 10-15 seconds. After the sleeve-shaped reinforcement material is fully in contact with the workpiece to be modified, the modification device is moved along the pre-set modification direction. During the movement, the downward pressure applied to the modification device is kept constant to ensure uniform consumption and replenishment of the sleeve-shaped reinforcement material.

[0011] When the modification reaches the end point, stop the spindle movement, lift the modification device to 3 to 5 mm from the modified surface, stop the spindle, and keep the modification device in this position until it cools down. During this period, keep the protective gas supply for 1 to 3 minutes;

[0012] After the modification device is completely cooled, the modification device is lifted to complete the modification process.

[0013] In combination with the first aspect, further, the sleeve-shaped reinforcement material is loaded into the clamping device to obtain an assembled device, comprising:

[0014] Place the top end of the sleeve-shaped reinforcement material into the second cavity of the clamping device. After ensuring that the end face of the second cavity is tightly fitted with the upper end face of the sleeve-shaped reinforcement material, confirm again that the clamping device profile coincides with the sleeve profile. Then, screw two flat-bottomed set screws through the threaded holes on the clamping device to complete the fixation of the clamping device and the sleeve-shaped reinforcement material to obtain a combined device.

[0015] In combination with the first aspect, further, fixing the assembly device to the friction stir welding machine includes:

[0016] The combined device is installed in the tool holder of the friction stir welding machine through the upper part of the clamping device, and ensures that the top surface of the clamping device and the bottom screw position of the tool holder are tightly fitted, and then confirmed with the bottom end of the sleeve-shaped reinforcement material as the zero point.

[0017] In combination with the first aspect, further, the stirring rod is installed into the combined device to obtain the modification device, comprising:

[0018] The stirring rod is inserted into the inner cavity of the sleeve-shaped reinforcement material, ensuring that the end surface of the first cavity of the clamping device is tightly matched with the top of the stirring rod to obtain a modified device.

[0019] In combination with the first aspect, further, the rotation speed of the main shaft is 100 r / min to 700 r / min; and the moving speed of the main shaft is 10 mm / min to 50 mm / min.

[0020] In the second aspect, the present invention proposes an eddy current stir friction modification device for modifying a workpiece to be modified, comprising a clamping device, a sleeve-shaped reinforcing material fixedly connected to the clamping device, and a stirring rod; the upper part of the clamping device is connected to the tool handle of the stir friction welding machine, and a first cavity for accommodating the stirring rod and a second cavity for accommodating the sleeve-shaped reinforcing material are respectively provided inside; the sleeve-shaped reinforcing material is the source of the modifying element.

[0021] In combination with the second aspect, further, the clamping device includes a top profile, a reducing section, a first cavity end face, a second cavity end face, a first cavity, a second cavity, a clamping device profile and a threaded hole; the upper part of the clamping device is connected to the tool handle of the friction stir welding machine, and is axially fixed by relying on the reducing section arranged on the upper part of the clamping device, and the clamping device and the tool handle are further fixed by the close fit between the flat bottom set screw at the bottom of the tool handle and the top profile to transmit torque; the first cavity end face is arranged at the top of the first cavity, and is in contact with the stir The upper end surface of the rod contacts the second cavity; the second cavity end surface is arranged at the top of the second cavity, and contacts the upper end portion of the sleeve-shaped reinforcement material for axial positioning; the sleeve-shaped reinforcement material includes an internal cavity and a sleeve profile arranged at the top, the sleeve profile is matched with the clamping device profile, and two flat-bottomed set screws are screwed into the threaded holes of the clamping device, thereby achieving complete fixation of the clamping device and the sleeve-shaped reinforcement material; the internal cavity is used to accommodate the stirring rod, and the internal cavity and the stirring rod have the same configuration, thereby satisfying torque transmission.

[0022] In conjunction with the second aspect, further, the stirring rod is triangular, square, or other shape that satisfies torque transmission; the shape of the first cavity matches the shape of the stirring rod, and the first cavity and the second cavity are distributed in a stepped manner along the circumference. The second cavity is circular and partially provided with a clamping device profile that matches the sleeve profile.

[0023] In combination with the second aspect, further, the stirring rod is made of the same material as the workpiece to be modified.

[0024] In combination with the second aspect, further, the sleeve-shaped reinforcement material is one of cemented carbide, ceramic material, nickel-based alloy, high entropy alloy and nanomaterial prepared by processes such as powder sintering, chemical vapor deposition, electroplating and laser cladding.

[0025] In combination with the second aspect, further, the material of the clamping device is tool steel.

[0026] In combination with the second aspect, further, the length of the sleeve-shaped reinforcing material can be adjusted arbitrarily under the premise of meeting the equipment processing capacity and the assembly of the combined modification device, and the length of the stirring rod protrudes 0-1 mm from the bottom end of the sleeve-shaped reinforcing material after the installation is completed.

[0027] The present invention is used to modify aluminum alloys, magnesium alloys, low carbon steel, stainless steel, titanium alloys and other materials with thermoplastic properties, and can prepare composite material modified layers such as cemented carbide, ceramic materials, nickel-based alloys, high entropy alloys and nanomaterials for selected materials.

[0028] Compared with the prior art, the present invention provides a eddy current stir friction modification method and modification device, which have the following beneficial effects:

[0029] (1) The modification method of the present invention replaces the traditional stirring tool with an eddy current, thereby avoiding direct contact between the stirring tool and the modifying element, thereby effectively avoiding tool wear, especially when preparing a modified layer of a composite material with a higher hardness, which undoubtedly greatly reduces the production cost. In addition, the modification method of the present invention does not require a more complicated pretreatment of the plate before modification, thereby improving the processing efficiency.

[0030] (2) By using the modification method of the present invention in combination with the multi-stage combined modification device of the present invention, a fine modified layer that is evenly distributed along the thickness direction can be prepared. The microhardness and wear resistance of the modified layer are greatly improved. It can also efficiently and cost-effectively modify other materials with thermoplastic properties such as aluminum alloys, magnesium alloys, low carbon steel, stainless steel, titanium alloys, etc., thereby improving the mechanical properties of the materials. For selected materials, composite modified layers such as cemented carbide, ceramic materials, nickel-based alloys, high entropy alloys and nanomaterials can be prepared, which has excellent process universality.

[0031] (3) The clamping device in the modification device of the present invention does not actually participate in the processing, but only plays the role of fixing and torque transmission, so it can be reused many times. The sleeve-shaped reinforcement material can be selected from cemented carbide, ceramic materials, nickel-based alloys, high entropy alloys and nanomaterials prepared by processes such as powder sintering, chemical vapor deposition, electroplating and laser cladding. The sleeve length can be adjusted according to actual conditions before processing. During the processing, the pressure under the modification device is monitored to compensate for the sleeve consumption length. After processing, the used sleeve can be replaced, which greatly improves the flexibility of the eddy current stir friction modification process. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the principle of the eddy current stir friction modification method of the present invention, Figure 1 The three nodes from left to right are eddy current induction, reaction product generation, and composite material modification layer;

[0033] Figure 2 Schematic diagram of the three-dimensional structure of the eddy current stir friction modification device of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of the clamping device used in Examples 1, 2 and 3 of the present invention, wherein Figure 3 a is a schematic diagram of the three-dimensional structure of the clamping device, Figure 3 b is a schematic diagram of the cross-sectional structure of the clamping device;

[0035] Figure 4 Schematic diagram of the structure of the sleeve-shaped reinforcement material used in Examples 1, 2 and 3 of the present invention, Figure 4 a is a schematic diagram of the three-dimensional structure of the sleeve-shaped reinforcement material. Figure 4b is a schematic diagram of the cross-sectional structure of the sleeve-shaped reinforcement material.

[0036] Figure 5 Schematic diagram of the stirring rod structure used in Examples 1, 2 and 3 of the present invention.

[0037] Figure 6 Schematic diagram of the macroscopic morphology of the cross section of the modified layer in Example 1 of the present invention, wherein W is the distribution distance of the modified layer in the width direction; H is the distribution distance of the modified layer in the thickness direction; RS represents the retreat side, that is, the rotation direction of the modifying device is opposite to the forward direction; AS represents the forward side, indicating that the rotation direction of the modifying device is the same as the forward direction.

[0038] Figure 7 Schematic diagram of the macroscopic morphology of the cross section of the modified layer of Example 2 of the present invention, wherein W is the distribution distance of the modified layer in the width direction; H is the distribution distance of the modified layer in the thickness direction; RS represents the retreating side; AS represents the advancing side.

[0039] Figure 8 Schematic diagram of the macroscopic morphology of the cross section of the modified layer of Example 3 of the present invention, wherein W is the distribution distance of the modified layer in the width direction; H is the distribution distance of the modified layer in the thickness direction; RS represents the retreating side; AS represents the advancing side.

[0040] Figure 9 This is a graph showing the change in friction and wear coefficient of the sample before and after modification in Example 1 of the present invention, where: Figure 9 a is a schematic diagram of the friction and wear characteristics of the substrate before modification. Figure 9 b is a schematic diagram of the friction and wear characteristics of the modified substrate.

[0041] Figure 10 This is the wear cross-sectional profile of the sample before and after modification in Example 1 of the present invention, where: Figure 10 a is a schematic diagram of the wear interface profile of the substrate before modification. Figure 10 b is a schematic diagram of the wear interface profile of the modified substrate.

[0042] The meanings of the reference numerals in the figures are:

[0043] 1. Clamping device; 11. Disassembly hole; 12. Top profile; 13. Variable diameter section; 14. First cavity end face; 15. First cavity; 16. Second cavity end face; 17. Clamping device profile; 18. Threaded hole; 19. Second cavity; 2. Sleeve-shaped reinforcement material; 21. Internal cavity; 22. Sleeve profile; 3. Stirring rod; 4. Workpiece to be modified; 41. Modified layer. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. Technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may also include different values. It should be noted that similar numbers and letters represent similar items in the following drawings, and therefore, once an item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0046] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the protection content of the present invention.

[0047] Example 1

[0048] like Figures 1 to 5 As shown, this embodiment proposes an eddy current stir friction modification device for modifying a workpiece to be modified, comprising a clamping device 1, a sleeve-shaped reinforcing material 2 fixedly connected to the clamping device 1, and a stirring rod 3; the upper part of the clamping device 1 is connected to the tool handle of the stir friction welding machine, and a first cavity 15 for accommodating the stirring rod 3 and a second cavity 19 for accommodating the sleeve-shaped reinforcing material 2 are respectively provided inside; the sleeve-shaped reinforcing material 2 is the source of the modifying element.

[0049] In this embodiment, a specific implementation method is as follows: Figure 3 a. Figure 3 b. Figure 4 a. Figure 4 b and Figure 5As shown, the clamping device 1 includes a top profile 12, a reducing section 13, a first cavity end face 14, a second cavity end face 16, a first cavity 15, a second cavity 19, a clamping device profile 17 and a threaded hole 18; the upper part of the clamping device 1 is connected to the tool handle of the friction stir welding machine, and is axially fixed by the reducing section 13 provided on the upper part of the clamping device 1, and the clamping device 1 and the tool handle are further fixed by the close fit between the flat bottom set screw at the bottom of the tool handle and the top profile 12 to transmit torque; the first cavity end face 14 is provided at the top of the first cavity 15, and is in contact with the stirring rod 3 The second cavity end face 16 is arranged at the top of the second cavity 19 and contacts the upper end portion of the sleeve-shaped reinforcement material 2 for axial positioning; the sleeve-shaped reinforcement material 2 includes an internal cavity 21 and a sleeve profile 22 arranged at the top, the sleeve profile 22 is matched with the clamping device profile 17, and two flat-bottomed set screws are screwed into the threaded hole 18 of the clamping device 1, thereby achieving complete fixation of the clamping device 1 and the sleeve-shaped reinforcement material 2; the internal cavity 21 is used to accommodate the stirring rod 3, and the internal cavity 21 and the stirring rod 3 have the same configuration, thereby satisfying torque transmission.

[0050] See also Figure 1 Based on the modification device of this embodiment, the eddy current stir friction modification method is selected to modify the workpiece to be modified, including the following steps:

[0051] Step S1: Place the top end of the sleeve-shaped reinforcement material 2 into the circular second cavity 19 at the bottom of the clamping device. After ensuring that the circular second cavity end surface 16 is in close contact with the upper end surface of the sleeve-shaped reinforcement material 2, confirm again that the clamping device profile 17 coincides with the sleeve profile 22 of the sleeve-shaped reinforcement material 2. Then, screw two flat-bottomed set screws through the threaded holes 18 of the clamping device 1 to secure the clamping device 1 and the sleeve-shaped reinforcement material 2, thereby obtaining an assembled device.

[0052] Step S2: The assembly obtained in step S1 is installed in the tool holder of the friction stir welding machine through the upper reducing section 13 of the clamping device 1, and the top profile 12 of the clamping device 1 is ensured to be closely fitted with the screw position at the bottom of the tool holder. Then, the bottom end of the sleeve-shaped reinforcement material 2 is used to confirm the zero point.

[0053] Step S3: insert the stirring rod 3 from the inner cavity 21 of the sleeve-shaped reinforcing material 2, ensuring that the first cavity end surface 14 of the clamping device 1 is tightly fitted with the top end of the stirring rod 3, thereby obtaining the modification device of this embodiment;

[0054] Step S4: 99.99% argon is introduced as a shielding gas, and the modification device obtained in step S3 is rotated and pressed downward using a set program. The rotation speed is set to 300 r / min, and the bottom end of the sleeve-shaped reinforcement material 2 is pressed into the workpiece to be modified by 0.1 mm. The workpiece is held for 10-15 seconds. After the materials are fully in contact, the modification device is moved along a pre-set modification direction at a controlled movement speed of 30 mm / min. During the movement, the downward pressure applied to the modification device is maintained constant to ensure uniform consumption and replenishment of the sleeve-shaped reinforcement material 2.

[0055] Step S5: When the modification reaches the end point, the main shaft of the friction stir welding machine is stopped, and when the modification device is lifted 3-5 mm from the modified surface, the main shaft of the friction stir welding machine is stopped, and the modification device is kept in this position until it cools down, during which the protective gas is kept supplied for 1-3 minutes;

[0056] Step S6: After the modification device is completely cooled, the modification device of this embodiment is lifted to complete the modification process; the stirring rod 3 can be knocked with a rod through the disassembly hole 11 to complete the disassembly of the stirring rod 3.

[0057] Specifically, the modified workpiece 4 and stirring rod 3 used in this embodiment are both made of TC4 material. The stirring rod 3 is square in shape, and the sleeve-shaped reinforcement material 2 is a WC material prepared by powder sintering and has a square through-hole inside. It should be noted that the surface reinforcement of the modified workpiece is based on the sleeve-shaped reinforcement material 2. To facilitate installation and connection with other parts, the reinforcement material is processed into a sleeve shape to obtain the sleeve-shaped reinforcement material 2.

[0058] See also Figure 6 , is the microscopic morphology of the cross section of the sample after modification in this embodiment. The modified layer extends to ~9.474 mm in the width direction and ~0.962 mm in the thickness direction, that is, W=9.474 mm, H=0.962 mm.

[0059] The microhardness of the modified layer prepared on the titanium alloy surface in this embodiment was tested using an MHVS-1000Z touch screen digital display microhardness tester. The test parameters were: experimental load 1.96 N (200 gf), dwell time 10 s, and the test results were: the hardness of the modified layer on the titanium alloy surface in this embodiment was 402.9 HV 0.2 ~423.5 HV 0.2, which is higher than the microhardness of the workpiece 4 to be modified. The friction performance of the modified layer prepared on the titanium alloy surface in this embodiment was tested using a UMT-2 friction and wear testing machine. The wear mode was linear reciprocating motion. The surface of the modified layer 41 was a disk, and the pair was a 6mm diameter Si3N4 ball. The load was 20 N, the friction rate was 20 mm / s, the friction stroke was 8 mm, and the test time was 30 min. The wear rate was used to characterize the wear resistance. Figure 9 a. Figure 9 b. Figure 10 a and Figure 10 As shown in b, it can be found that the average friction coefficient, weight loss rate and wear volume of the modified layer prepared in this embodiment are 0.389, 0.98 mg and 5.042 mm, respectively. 3 / (N m), while those of TC4 parent material are 0.403, 1.11 mg and 6.543 mm respectively. 3 / (N×m), and the friction coefficient in the stable stage shows that the average friction coefficient of the modified layer in the stable friction stage is 0.363, while that of the TC4 base material is 0.360. This shows that in the stable friction stage, the friction coefficients of the two are similar, and after the stable wear enters the severe wear stage, the friction coefficient of the TC4 base material increases. Further, the wear profile is statistically analyzed. Figure 10 As can be seen in Figure b, the maximum width and maximum depth of the wear profile of the modified layer are 1384.95 μm and 53.28 μm, respectively, with an average depth of 28.43 μm. In contrast, the maximum width and maximum depth of the wear profile of the TC4 base material are 1549.80 μm and 71.72 μm, respectively, with an average depth of 41.88 μm. It can be seen that the modified layer has a lower friction coefficient, weight loss rate, and wear volume, and a shallower and narrower wear profile, indicating that the prepared modified layer has superior tribological properties, enabling the sample to serve in more severe working environments, thus achieving the modification goal.

[0060] Example 2

[0061] See also Figures 1 to 5 This embodiment provides a method for modifying a workpiece 4 to be modified using the modification device in embodiment 1. The steps of the modification method are basically the same as those in embodiment 1, with the only difference being that the spindle speed in step S4 is different.

[0062] Step S4 of this embodiment is as follows: 99.99% argon is introduced as a shielding gas, and the assembly device is rotated and pressed downward using a set program. The rotation speed is set to 500 r / min, and the bottom end of the sleeve-shaped reinforcing material 2 is ensured to be pressed into the workpiece to be modified by 0.1 mm. The workpiece is kept in contact for 10-15 seconds. After the materials are fully contacted, the modifying device is moved along a pre-set modification direction at a controlled movement speed of 30 mm / min. During the movement, the downward pressure applied to the modifying device is kept constant to ensure uniform consumption and replenishment of the sleeve-shaped reinforcing material 2.

[0063] Specifically, the workpiece to be modified 4 and the stirring rod 3 used in this embodiment are both made of TC4 material, the stirring rod 3 is square, and the sleeve-shaped reinforcement material 2 is a WC material prepared by powder sintering, and has a square through hole inside.

[0064] See also Figure 7 , is the microscopic morphology of the cross section of the sample after modification in this embodiment. The modified layer extends ~20.256 mm in the width direction and ~1.038 mm in the thickness direction, that is, W=20.256 mm, H=1.038 mm.

[0065] The microhardness of the modified layer prepared on the titanium alloy surface in this embodiment was then tested using the same test method as in Example 1. The test results showed that the surface hardness of the modified layer prepared in this embodiment was 415.5 HV 0.2 ~463.3 HV 0.2 , which is much better than the hardness of the workpiece 4 to be modified. The friction performance of the modified layer prepared in this embodiment was tested by the same test method as in Example 1. The test results are as follows: the friction coefficient, weight loss rate and wear volume of the modified layer prepared in this embodiment are 0.350, 0.78 mg and 4.201 mm respectively. 3 / ( ).

[0066] Example 3

[0067] See also Figures 1 to 5 This embodiment 3 provides a method for modifying the workpiece 4 to be modified using the modification device in embodiment 2. The steps of the modification method are basically the same as those in embodiment 2, with the difference that the spindle movement speed in step S4 is different, and the materials of the workpiece 4 to be modified and the stirring rod 3 are different.

[0068] Step S4 of this embodiment is as follows: 99.99% argon is introduced as a shielding gas, and the assembly device is rotated and pressed downward using a set program. The speed is set to 500 r / min, and the bottom end of the sleeve-shaped reinforcing material 2 is pressed into the workpiece to be modified by 0.1 mm. After staying for 10-15 seconds to allow the materials to fully contact, the device is moved along a pre-set modification direction at a controlled movement speed of 20 mm / min. During the movement, the downward pressure applied to the modification device is kept constant to ensure uniform consumption and replenishment of the sleeve-shaped reinforcing material 2.

[0069] Specifically, the workpiece to be modified 4 and the stirring rod 3 used in the embodiment are both made of SPCC material, the stirring rod is square, and the sleeve-shaped reinforcement material 2 is a WC material prepared by powder sintering, and has a square through hole inside.

[0070] See also Figure 8 , Figure 8 The cross-sectional micromorphology of the modified sample in this example is shown below. The modified layer extends approximately 14.048 mm in width and 0.952 mm in thickness, i.e., W = 14.048 mm and H = 0.952 mm.

[0071] Subsequently, the microhardness of the modified layer prepared on the surface of SPCC steel in this embodiment was tested using the same test method as in Example 2. The test results showed that the surface hardness of the modified layer prepared in this embodiment was 121.00 HV 0.2 ~156.20 HV 0.2 , compared with the unmodified material (surface hardness of 108.93±5.86 HV 0.2 ) increased by 11.08%~43.39%.

[0072] Examples 1, 2 and 3 have verified the application of the modification method proposed in the patent and the multi-stage combined processing modification device matched therewith in titanium alloys and low-carbon steel, and have indirectly highlighted the great potential of this modification method and the modification device matched therewith in modifying other metals to improve mechanical properties.

[0073] It should be noted that, in this application, relational terms such as first and second, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. In the absence of further restrictions, an element defined by the statement "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.

[0074] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A eddy current stir friction modification method, characterized in that: A stirring rod made of the same material as the workpiece to be modified and a sleeve-shaped reinforcement material sleeved on the outside of the stirring rod are used as stirring tools to rub against the workpiece to be modified, inducing the generation of plastic eddy currents inside the workpiece to be modified, which gradually expands into a thermal-fluid coupling region. Under the heat-fluid coupling action of the plastic eddy current, the sleeve-shaped reinforcement material undergoes a metallurgical reaction with the workpiece to be modified, and transitions to the interior of the workpiece to be modified through decomposition, replacement reaction, synthesis, solid solution and diffusion, forming a reinforcement phase or solid solution reaction product; the reaction product is uniformly mixed with the material of the workpiece to be modified under the stirring action of the eddy current to form a composite material modified layer, which is distributed on the upper surface of the workpiece to be modified.

2. The eddy current stir friction modification method according to claim 1, wherein The following steps are involved: The sleeve-shaped reinforcement material is loaded into the clamping device to obtain an assembled device; Fixing the combined device to the friction stir welding machine; The stirring rod is installed into the combined device to obtain a modified device; The protective gas is introduced, and the modification device is rotated and pressed downward to ensure that the bottom end of the sleeve-shaped reinforcement material is pressed into the workpiece to be modified by 0 to 0.2 mm. After the sleeve-shaped reinforcement material is fully in contact with the workpiece to be modified, the modification device is moved along the pre-set modification direction; When the modification reaches the end point, stop the spindle movement, lift the modification device to 3 to 5 mm from the modified surface, stop the spindle, and keep the modification device in this position until it cools down, during which time the protective gas supply is maintained for 1 to 3 minutes; After the modification device is cooled, the modification device is lifted to complete the modification process.

3. A eddy current stir friction modification method according to claim 2, characterized in that, The sleeve-shaped reinforcement material is loaded into the clamping device to obtain an assembled device, comprising: Place the top end of the sleeve-shaped reinforcement material into the second cavity of the clamping device. After ensuring that the end face of the second cavity is tightly fitted with the upper end face of the sleeve-shaped reinforcement material, confirm again that the clamping device profile coincides with the sleeve profile. Then, screw the set screw through the threaded hole on the clamping device to complete the fixation of the clamping device and the sleeve-shaped reinforcement material to obtain a combined device.

4. A eddy current stir friction modification method according to claim 2, characterized in that, The method of fixing the combined device to the friction stir welding machine comprises: The combined device is installed in the tool holder of the friction stir welding machine through the upper part of the clamping device, and ensures that the top surface of the clamping device and the bottom screw position of the tool holder are tightly fitted, and then confirmed with the bottom end of the sleeve-shaped reinforcement material as the zero point.

5. The eddy current stir friction modification method according to claim 2, characterized in that: The stirring rod is installed in the combined device to obtain a modification device, comprising: The stirring rod is inserted into the inner cavity of the sleeve-shaped reinforcement material, ensuring that the end surface of the first cavity of the clamping device is tightly matched with the top of the stirring rod to obtain a modified device.

6. The eddy current stir friction modification method according to claim 2, wherein: The rotation speed of the main shaft is 100 r / min to 700 r / min; the moving speed of the main shaft is 10 mm / min to 50 mm / min.

7. An eddy current stir friction modification device, characterized in that: It is used to modify the workpiece to be modified, including a clamping device, a sleeve-shaped reinforcing material fixedly connected to the clamping device, and a stirring rod; the upper part of the clamping device is connected to the tool handle of the stir friction welding machine, and a first cavity for accommodating the stirring rod and a second cavity for accommodating the sleeve-shaped reinforcing material are respectively provided inside; the sleeve-shaped reinforcing material is the source of the modifying element.

8. The eddy current stir friction modification device according to claim 7, characterized in that: The clamping device includes a first cavity end face, a second cavity end face, a first cavity, a second cavity, a clamping device profile and a threaded hole; the upper part of the clamping device is connected to the tool handle of the stir friction welding machine; the first cavity end face is arranged at the top of the first cavity and contacts the upper end face of the stirring rod; the second cavity end face is arranged at the top of the second cavity and contacts the upper end part of the sleeve-shaped reinforcement material for axial positioning; the sleeve-shaped reinforcement material includes an internal cavity and a sleeve profile arranged at the top, the sleeve profile is matched with the clamping device profile, and a set screw is screwed into the threaded hole of the clamping device to achieve fixation of the clamping device and the sleeve-shaped reinforcement material; the internal cavity is used to accommodate the stirring rod, and the internal cavity and the stirring rod have the same configuration, thereby satisfying torque transmission.

9. The eddy current stir friction modification device according to claim 7, characterized in that: The stirring rod is made of the same material as the workpiece to be modified.

10. The eddy current stir friction modification device according to claim 7, characterized in that: The sleeve-shaped reinforcement material is one of hard alloy, ceramic material, nickel-based alloy, high entropy alloy and nano material.

Images