Pressure resistance welding method and device for ODS steel T-shaped connector thin-wall part

Abstract

The invention relates to a pressure resistance welding method and device for an ODS steel T-shaped connector thin-wall part, and belongs to the technical field of nuclear material welding. According to the welding method, when the technological parameters are as follows: the welding current is 2.0-10.6 kA, the welding time is 12-59 ms, and the electrode pressure is 1-5.5 kN, no large-size interface oxide exists at the position of an obtained welding interface, and nanometer oxides are distributed in a welding interface deformation area in a dispersed mode. Meanwhile, a resistance welding matching device is needed and comprises an upper electrode, a lower electrode, a clamp and a copper cushion block, the lower electrode is composed of a bakelite layer and a copper alloy layer, isolates current conduction between the lower electrode and the clamp and is provided with a groove matched with the clamp to be used for restraining the welding part A, and the clamp is provided with a limiting block and a reserved groove to restrain the welding part B and the copper cushion block. The size of the cushion block is matched with the size of a reserved groove of the clamp, and the height of the part exceeding the clamp is larger than 1mm. The method not only can be used for welding the reactor core structure of an advanced nuclear energy system, but also can be popularized and applied to welding of other materials and structures in the fields of thermal power, aviation, aerospace and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear material welding, and in particular to a method and device for pressure resistance welding of thin-walled parts of oxide dispersion strengthened (ODS) steel T-joints. Background Art

[0002] Oxide dispersion strengthened (ODS) steel has attracted wide attention in nuclear engineering research due to its excellent high-temperature strength, radiation resistance and corrosion resistance, and is expected to become one of the most promising structural materials in the next generation of nuclear energy systems. At present, the application of ODS steel in the fourth-generation fission reactors and fusion reactors has been widely studied, including the first wall structure in tokamaks, advanced fuel cladding systems and high-temperature steam pipelines in supercritical water-cooled reactor configurations.

[0003] Welding of ODS steel faces a key challenge: traditional fusion welding causes melting of the material, which will lead to dissolution and agglomeration coarsening of Y-Ti-O nanoparticles in the material, resulting in a decrease in the strength of the material and damage to its radiation resistance. Solid-state joining techniques achieve the joining of metal materials through atomic diffusion and recrystallization caused by plastic deformation. There is no melting of the material during the welding process, effectively preventing thermal damage to the nanoparticles in the material and ensuring the dispersion of the nanoparticles. Therefore, it has become the most promising method to solve the welding problem of ODS steel. Pressure resistance welding belongs to a kind of solid-state joining technique and realizes the rapid joining of components by applying resistance heat and pressure. T-joints are a common type of structure. Based on the differential method, the fuel rod cladding can also be regarded as an annular structure composed of countless T-joints. Matching a suitable pressure resistance welding process and device for thin-walled parts of ODS steel T-joints can significantly improve the joint reliability. This is because when the resistance welding process is inappropriate, it will lead to the deterioration of the performance of ODS steel, thereby reducing or even losing its original performance. In addition, all existing devices for resistance welding of ODS steel are special devices, and there is no ordinary resistance welding device and pressure resistance welding method applicable to thin-walled parts of ODS steel T-joints. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for pressure resistance welding of thin-walled parts of ODS steel T-joints, which can ensure that nano-oxides (size ≤ 50 nm) in the deformation zone of the welding interface are dispersed and do not undergo severe coarsening, and there are no large-size interface oxides at the welding interface that damage the mechanical properties of the joint.

[0005] In order to achieve the above purpose, the technical solutions adopted by the present invention are as follows:

[0006] A pressure resistance welding device for thin-walled parts of ODS steel T-joints, comprising an upper electrode, a lower electrode, a fixture and a copper pad; a groove penetrating through the cross-section is opened at the top end of the lower electrode; the fixture is installed above the lower electrode, a limiting groove corresponding to the top end of the lower electrode is opened at the bottom of the fixture, a reserved groove communicating with the limiting groove is opened on the top surface of the fixture, a limiting block is convexly provided on the inner side surface of the limiting groove and outside the reserved groove, and the limiting block is used for inserting into the groove on the lower electrode to limit and fix the welding part A, and the reserved groove is used for limiting and fixing the welding part B and the copper pad; the copper pad is arranged in the reserved groove of the fixture, the upper surface of the copper pad contacts the lower surface of the upper electrode, and the lower surface of the copper pad contacts the upper surface of the welding part B, and is used for pressing the welding part A and the welding part B, the outer contour shape of the copper pad matches the reserved groove, and the height of the copper pad above the upper surface of the fixture is greater than or equal to 1 mm.

[0007] Further, the shape of the groove on the lower electrode matches the welding part A, and the shape of the reserved groove on the fixture matches the welding part B.

[0008] Further, the lower electrode is composed of two materials, copper alloy and bakelite; the bakelite is inlaid on the upper layer of the copper alloy to form a bakelite layer and a copper alloy layer, and the shape of the bakelite layer matches the position where the lower electrode contacts the fixture, and is used for isolating the current conduction between the lower electrode and the fixture.

[0009] A pressure resistance welding method for thin-walled parts of ODS steel T-joints, comprising the following steps:

[0010] (1) Clean the welding parts A and B required for welding the T-joint thin-walled parts, and then dry them;

[0011] (2) Raise the upper electrode of the pressure resistance welding device according to claim 1, insert the welding part A into the middle position of the groove of the lower electrode, install the fixture on the lower electrode, then put the welding part B into the reserved groove of the fixture, place the copper pad, and lower the upper electrode until it contacts the upper surface of the copper pad;

[0012] (3) Set the resistance welding process parameters to achieve welding, and the welding parameters include welding current, welding time and electrode pressure.

[0013] Furthermore, the thin-walled T-joint is formed by welding the welding component A and the welding component B. The welding component A is a rectangular structural member with a predetermined thickness, and the thickness dimension of the welding component A is equal to the width of the groove at the top end of the lower electrode. The length direction of the welding component A is 0.2 - 0.5 mm higher than the upper surface of the lower electrode. The welding component B is also a rectangular structural member with a predetermined thickness, and a boss with a height of 0.2 - 0.5 mm is provided at a position corresponding to the welding component A. The thicknesses of the welding component A and the welding component B are 0.3 - 3 mm.

[0014] Furthermore, at the welding interface of the ODS steel T-joint prepared by the pressure resistance welding method, the size of the oxide is ≤ 0.5 μm, and nano-oxides are diffusely distributed in the deformation zone of the welding interface, and the particle size of the nano-oxides is ≤ 50 nm.

[0015] Furthermore, the welding process parameters in step (3) are as follows: the welding current is 2.0 - 10.6 kA, the welding time is 12 - 59 ms, and the electrode pressure is 1 - 5.5 kN.

[0016] Furthermore, when the thickness of the welding material is less than or equal to 1 mm, the welding process parameters are: the welding current is 2 - 5 kA, the welding time is 11 - 32 ms, and the electrode pressure is 1 - 2.5 kN; the preferred welding process parameters are: the welding current is 2 - 3 kA, the welding time is 25 - 32 ms, and the electrode pressure is 1 - 1.5 kN; or it is set as: the welding current is 3 - 4 kA, the welding time is 18 - 25 ms, and the electrode pressure is 1.5 - 2 kN; or it is set as: the welding current is 4 - 5 kA, the welding time is 11 - 18 ms, and the electrode pressure is 2 - 2.5 kN.

[0017] Furthermore, when the thickness of the welding material is 1 - 2 mm, that is, 1 mm < thickness ≤ 2 mm, the welding process parameters are: the welding current is 4.8 - 7.8 kA, the welding time is 25 - 46 ms, and the electrode pressure is 2.5 - 4 kN; the preferred welding process parameters are: the welding current is 4.8 - 5.8 kA, the welding time is 39 - 46 ms, and the electrode pressure is 2.5 - 3 kN; or it is set as: the welding current is 5.8 - 6.8 kA, the welding time is 32 - 39 ms, and the electrode pressure is 3 - 3.5 kN; or it is set as: the welding current is 6.8 - 7.8 kA, the welding time is 25 - 32 ms, and the electrode pressure is 3.5 - 4 kN.

[0018] Further, when the thickness of the welding material is 2 - 3 mm, i.e., 2 mm < thickness ≤ 3 mm, the welding process parameters are: welding current 7.6 - 10.6 kA, welding time 38 - 59 ms, electrode pressure 4 - 5.5 kN; the preferred welding process parameters are: welding current 7.6 - 8.6 kA, welding time 52 - 59 ms, electrode pressure 4 - 4.5 kN; or set as: welding current 8.6 - 9.6 kA, welding time 45 - 52 ms, electrode pressure 4.5 - 5 kN; or set as: welding current 9.6 - 10.6 kA, welding time 38 - 45 ms, electrode pressure 5 - 5.5 kN.

[0019] Advantages of the present invention:

[0020] A pressure resistance welding method and device for ODS steel T-joint thin-walled parts disclosed by the present invention can obtain no large interfacial oxides (size ≤ 0.5 μm) at the welding interface, and the nano-oxides (size ≤ 50 nm) in the welding interface deformation zone are diffusely and evenly distributed, and the nano-oxides will not undergo serious coarsening. It can ensure the strength and radiation resistance performance of the joint.

[0021] The present invention is applicable to ordinary resistance welders, greatly reducing the welding cost. The resistance welding device of the present invention has a simple structure, is convenient for installation and disassembly. The fixture can directly restrict the movement of the welding component A and does not affect the flow direction of the resistance welding current, improving the welding efficiency while ensuring the welding effect.

[0022] The welding process of the present invention for ODS steel has a wide range of application fields. It can not only be used for the welding of the core structure of advanced nuclear energy systems, but also be extended to the welding of materials and structures used in other fields such as thermal power, aviation, and aerospace. Brief Description of the Drawings

[0023] Figure 1 It is a schematic assembly structure diagram of the pressure resistance welding device and the welding component of the present invention;

[0024] In the figure: 1 - lower electrode; 2 - fixture; 3 - welding component; 4 - copper pad; 5 - upper electrode;

[0025] Figure 2 It is the front view of the lower electrode;

[0026] Figure 3 It is the top view of the lower electrode;

[0027] Figure 4 It is the side view of the lower electrode;

[0028] Figure 2-4 In it: 101 - bakelite layer; 102 - groove; 103 - copper alloy layer;

[0029] Figure 5 It is the front view of the special fixture;

[0030] Figure 6 It is the top view of the special fixture;

[0031] Figure 7 It is the side view of the special fixture;

[0032] Figure 5-7 In the figure: 201 - limit groove; 202 - reserved groove; 203 - limit block;

[0033] Figure 8 It is the pre - welding structure diagram of the welding component;

[0034] In the figure: 301 - welding component A; 302 - welding component B;

[0035] Figure 9 It is the post - welding appearance diagram of the welding component;

[0036] Figure 10 It is the scanning diagram of the welding interface after welding in Comparative Example 1;

[0037] Figure 11 It is the transmission diagram of the welding interface after welding in Example 1;

[0038] Figure 12 It is the macroscopic diagram of the oxide on the welding interface after welding in Comparative Example 2;

[0039] Figure 13 It is the macroscopic diagram of the welding interface without oxide after welding in Example 6. Specific embodiments

[0040] The following further describes in detail the above - mentioned inventive content of the present invention in combination with specific embodiments. However, this should not be construed as limiting the scope of the above - mentioned subject matter of the present invention to the following embodiments. Without departing from the above - mentioned technical idea of the present invention, various substitutions and modifications made according to ordinary technical knowledge and customary means in the art should be included within the scope of the present invention.

[0041] The embodiment of the present application discloses a pressure resistance welding device for thin - walled parts of ODS steel T - type joints.

[0042] Reference Figures 1-8, A pressure resistance welding device for thin-walled parts of ODS steel T-joints includes a lower electrode 1, a fixture 2, a copper pad 4 and an upper electrode 5. Among them, the lower electrode 1 and the fixture 2 are specially designed and used for the welding of thin-walled parts of T-joints. The lower electrode 1 of the welding device includes a main body copper alloy layer 103, and a bakelite layer 101 is inlaid on the copper alloy layer 103. The shape of the bakelite layer 101 matches the position where the lower electrode 1 contacts the fixture 2, and is used to isolate the current conduction between the fixture. A groove 102 is opened at the top of the lower electrode to restrain the welding part A301. A limit groove 201 is opened at the bottom of the fixture 2 for inserting the lower electrode 1 to restrain the fixture 2, and a limit block 203 is used to insert the lower electrode 1 and limit the movement of the welding part A301. A reserved groove 202 is opened on the top surface of the fixture 2 to restrain the welding part B302 and the copper pad 4. The outer contour shape of the copper pad 4 matches the reserved groove 202, and the height is 1 mm higher than the upper surface of the special fixture 2.

[0043] The embodiment of the present application discloses a pressure resistance welding method for thin-walled parts of ODS steel T-joints using the above welding device. The structures of the thin-walled parts of the T-joints before and after welding are shown in Figure 8 and Figure 9 , The thin wall means that the thickness H is in the range of 0.3 - 3 mm. The resistance welding machine used in this application is an intermediate frequency inverter DC spot welding machine of model DTBZ-160KA, with a rated power of 160 kVA, a maximum short-circuit current of 52 kA, and a maximum electrode pressure of 12000 N.

[0044] It includes the following steps:

[0045] Step 1: Clean the two parts required for welding the thin-walled parts of the T-joint: welding part A301 and welding part B302;

[0046] Step 2: Start the resistance welding machine, and the upper electrode 5 rises;

[0047] Step 3: Insert the welded part A301 cleaned in Step 1 into the groove 102 of the lower electrode of the pressure resistance welding device, and put the fixture 2 on the lower electrode 1;

[0048] Step 3: Insert the welded part B302 into the reserved groove 202 of the fixture, and place the copper pad 4 above the welded part B302;

[0049] Step 4: The upper electrode 5 descends to closely contact the copper pad 4, set the pressure resistance welding process parameters for welding. The upper electrode 5 presses down the copper pad 4 so that the welded part A301 and the welded part B302 are pressed tightly. During this process, due to the heat generated by energization, the parts to be connected undergo thermoplastic deformation, and finally the welded part A301 and the welded part B302 are connected through recrystallization;

[0050] Further, the cleaning of the two components required for welding the thin-walled T-joint includes the following process: First, use an automated grinding machine to grind the welding component A301 and the welding component B302 to be flat and shiny. Then, use ultrasonic waves to clean the oil stains on the surfaces of the welding component A301 and the welding component B302 twice. The medium is acetone or alcohol, and the ultrasonic cleaning time is 30 minutes. After that, use an electric hair dryer to blow dry the residual acetone or alcohol reagent on the surface. In resistance spot welding, if the specimens to be welded are stored for too long, a relatively thick oxide film will form on the surface, affecting the connection quality. Uneven surfaces of the components will also cause a decrease in the interface connection rate. Therefore, in this application, the surfaces to be welded are made flat and clean through machining, ultrasonic cleaning, and electric drying.

[0051] Further, in step 3, insert the cleaned welding component A301 into the reserved groove 102 of the lower electrode. The reserved groove 102 of the lower electrode is made of copper alloy to conduct electricity, and the part away from the reserved groove 102 of the lower electrode is a bakelite layer 101 for insulating the fixture 2. First, put the fixture 2 on the welding component A301, and then insert it along the reserved groove 102 of the lower electrode into the lower electrode 1, ensuring complete insertion.

[0052] Further, in step 3, insert the welding component B302 into the reserved groove 202 of the fixture 2. The bottom size of the welding component B302 matches the size of the reserved groove 202 of the fixture 2. Then, put the copper pad 4 into the reserved groove 202 of the fixture 2 so that the copper pad 4 contacts the bottom of the welding component B302. The outer contour size of the copper pad 4 matches the size of the reserved groove 202 of the fixture 2, and the height is 1 mm higher than the surface of the fixture 2.

[0053] Further, in step 4, the welding process conditions input on the control panel of the resistance spot welding machine are as follows: welding current 2.0 - 10.6 kA, welding time 12 - 59 ms, and electrode pressure 1 - 5.5 kN. This process can make the nano-oxides (particle size ≤ 50 nm) in the ODS steel at the welded joint disperse and not coarsen severely, and there are no large-size interfacial oxides (large-size interfacial oxides refer to particle size > 0.5 μm) that damage the mechanical properties of the joint at the welding interface.

[0054] For materials with a thickness H less than or equal to 1 mm, the welding process is as follows: welding current 2 - 5 kA, welding time 11 - 32 ms, and electrode pressure 1 - 2.5 kN. Further preferably: welding current 2 - 3 kA, welding time 25 - 32 ms, and electrode pressure 1 - 1.5 kN; or preferably: welding current 3 - 4 kA, welding time 18 - 25 ms, and electrode pressure 1.5 - 2 kN; or preferably: welding current 4 - 5 kA, welding time 11 - 18 ms, and electrode pressure 2 - 2.5 kN.

[0055] For materials with a thickness H of 1 - 2 mm, the welding process is as follows: welding current 4.8 - 7.8 kA, welding time 25 - 46 ms, and electrode pressure 2.5 - 4 kN. Further preferably: welding current 4.8 - 5.8 kA, welding time 39 - 46 ms, and electrode pressure 2.5 - 3 kN; or preferably: welding current 5.8 - 6.8 kA, welding time 32 - 39 ms, and electrode pressure 3 - 3.5 kN; or preferably: welding current 6.8 - 7.8 kA, welding time 25 - 32 ms, and electrode pressure 3.5 - 4 kN.

[0056] For materials with a thickness H of 2 - 3 mm, the welding process is as follows: welding current 7.6 - 10.6 kA, welding time 38 - 59 ms, and electrode pressure 4 - 5.5 kN. Further preferably: welding current 7.6 - 8.6 kA, welding time 52 - 59 ms, and electrode pressure 4 - 4.5 kN; or preferably: welding current 8.6 - 9.6 kA, welding time 45 - 52 ms, and electrode pressure 4.5 - 5 kN; or preferably: welding current 9.6 - 10.6 kA, welding time 38 - 45 ms, and electrode pressure 5 - 5.5 kN;

[0057] The welding process is adjusted according to the thickness H of the material to be welded. The thicker the material to be welded, the larger the welding current, the longer the welding time, and the higher the electrode pressure.

[0058] The materials used in the examples and comparative examples of the present invention are all oxide dispersion strengthened (ODS) steels, and their chemical compositions are shown in Table 1:

[0059] Table 1 Chemical composition of ODS steel (mass fraction %)

[0060] Cr W Ti Y Fe 12 2.0 0.25 0.3 balance

[0061] Example 1:

[0062] Joint form: T - type joint, material: ODS steel, width: 5 mm, thickness: 1.0 mm. The welding parameters are set as follows: welding current 5.0 kA, welding time 11 ms, and electrode pressure 2 kN. After welding, it is found that the connection quality of the welding interface is good (metallurgical bonding is achieved, the weld is uniform and continuous, without defects such as pores, cracks, and lack of fusion), there are no oxides larger than 0.5 μm, and there are nano - oxides distributed dispersedly inside the ODS steel at the joint. The size of the nano - oxides has not been severely coarsened compared with the base material (average particle size 6 nm), and the average particle size is 8.7 nm.

[0063] Example 2:

[0064] Joint form: T-joint, Material: ODS steel, Width: 5 mm, Thickness: 1.0 mm, Welding parameters are set as: Welding current 3.5 kA, Welding time 22 ms, Electrode pressure 1.8 kN. After welding, it is found that the connection quality of the welding interface is good, there is no oxide larger than 0.5 μm, there are nano-oxides distributed dispersedly near the interface, and the size of the nano-oxides has not been severely coarsened compared with the base material (6 nm), with an average size of 9.1 nm.

[0065] Example 3:

[0066] Joint form: T-joint, Material: ODS steel, Width: 5 mm, Thickness: 1.0 mm, Welding parameters are set as: Welding current 2.5 kA, Welding time 29 ms, Electrode pressure 1.3 kN. After welding, it is found that the connection quality of the welding interface is good, there is no oxide larger than 0.5 μm, there are nano-oxides distributed dispersedly near the interface, and the size of the nano-oxides has not been severely coarsened compared with the base material (6 nm), with an average size of 13.2 nm.

[0067] Example 4:

[0068] Joint form: T-joint, Material: ODS steel, Width: 5 mm, Thickness: 1.5 mm, Welding parameters are set as: Welding current 7.3 kA, Welding time 28 ms, Electrode pressure 3.7 kN. After welding, it is found that the connection quality of the welding interface is good, there is no oxide larger than 0.5 μm, there are nano-oxides distributed dispersedly near the interface, and the size of the nano-oxides has not been severely coarsened compared with the base material (6 nm), with an average size of 15.6 nm.

[0069] Example 5:

[0070] Joint form: T-joint, Material: ODS steel, Width: 5 mm, Thickness: 1.5 mm, Welding parameters are set as: Welding current 6.3 kA, Welding time 36 ms, Electrode pressure 3.3 kN. After welding, it is found that the connection quality of the welding interface is good, there is no oxide larger than 0.5 μm, there are nano-oxides distributed dispersedly near the interface, and the size of the nano-oxides has not been severely coarsened compared with the base material (6 nm), with an average size of 23.7 nm.

[0071] Example 6:

[0072] Joint form: T-joint, Material: ODS steel, Width: 5 mm, Thickness: 1.5 mm, Welding parameters are set as: Welding current 5.3 kA, Welding time 42 ms, Electrode pressure 2.7 kN. After welding, it is found that the connection quality of the welding interface is good, there is no oxide larger than 0.5 μm, there are nano-oxides distributed dispersedly near the interface, and the size of the nano-oxides has not been severely coarsened compared with the base material (6 nm), with an average size of 27.4 nm.

[0073] Example 7:

[0074] The joint was a T-joint made of ODS steel, 5 mm wide and 2.5 mm thick. The welding parameters were: welding current 10.1 kA, welding time 42 ms, and electrode pressure 5.3 kN. The weld interface was found to be of good quality, with no oxides larger than 0.5 μm. Nano-oxides were dispersed near the interface, but the nano-oxides were not significantly coarsened compared to the base metal (6 nm), with an average size of 23.2 nm.

[0075] Example 8:

[0076] The joint was a T-joint made of ODS steel, 5 mm wide and 2.5 mm thick. The welding parameters were: welding current 9.1 kA, welding time 49 ms, and electrode pressure 4.7 kN. The weld interface was found to be of good quality, with no oxides larger than 0.5 μm. Nano-oxides were dispersed near the interface, but the nano-oxides were not significantly coarsened compared to the base metal (6 nm), with an average size of 25.7 nm.

[0077] Example 9:

[0078] The joint was a T-joint, made of ODS steel, with a width of 5 mm and a thickness of 2.5 mm. The welding parameters were: welding current 8.1 kA, welding time 55 ms, and electrode pressure 4.3 kN. The weld interface was found to be of good quality, with no oxides larger than 0.5 μm. Nano-oxides were dispersed near the interface, but the nano-oxides were not significantly coarsened compared to the base metal (6 nm), with an average size of 29.3 nm.

[0079] Comparative Example 1:

[0080] The joint was a T-joint made of ODS steel, 5 mm wide and 1.0 mm thick. The welding parameters were 5.0 kA current, 9 ms welding time, and 2 kN electrode pressure. After welding, large, discontinuous oxides, up to 7 μm in size, were observed at the weld interface.

[0081] Comparative Example 2:

[0082] The joint was a T-joint made of ODS steel, 5 mm wide and 1.5 mm thick. The welding parameters were 7.5 kA, 25 ms, and 2 kN of electrode pressure. After welding, large, discontinuous oxides, up to 70 μm in size, were observed at the weld interface.

[0083] Comparative Example 3:

[0084] Joint form: T-joint, Material: ODS steel, Width: 5 mm, Thickness: 2.5 mm, Welding parameters are set as: Welding current 6 kA, Welding time 55 ms, Electrode pressure 4.3 kN. After welding, large-sized blocky discontinuous oxides were found at the welding interface, with the maximum size of 83 μm. The oxide condition at the welding interface is shown in Table 2.

[0085] Table 2 Sizes of large-sized interface oxides and nano-oxides in the deformation zone at the welding interface

[0086]

[0087] Using the pressure resistance welding method designed by the present invention, the process parameters used in Examples 1-9 are all within the scope of the present invention. The generation of large-sized interface oxides at the welding interface is avoided. Under the combined action of electrode pressure and resistance heat, sufficient high temperature and pressure accelerate the decomposition of large-sized interface oxides, and the short high-temperature holding time avoids the severe coarsening of nano-oxides inside the material, meeting the requirements of the technical solution of the present invention. The welding time of Comparative Example 1 is short, 9 ms, not within the scope of the technical solution of the present invention (welding time 11-18 ms). The large-sized interface oxides at the interface have no time to decompose, and the maximum size is 7 μm, not meeting the requirements of the technical solution of the present invention (oxide size ≤ 0.5 μm). The electrode pressure of Comparative Example 2 is small, 2 kN, not within the scope of the technical solution of the present invention (electrode pressure 3.5-4 kN). There is not enough pressure to break and accelerate the decomposition of interface oxides, resulting in the residue of interface oxides, with the maximum size of 70 μm, not meeting the requirements of the technical solution of the present invention (oxide size ≤ 0.5 μm). The welding current of Comparative Example 3 is low, 6 kA, not within the scope of the technical solution of the present invention (7.6-8.6 kA). The welding heat input is too small, resulting in incomplete decomposition of interface oxides, with the maximum size of 83 μm, not meeting the requirements of the technical solution of the present invention (oxide size ≤ 0.5 μm).

[0088] Figure 9 The post-welding appearance diagram is shown. Only a small amount of extrusion deformation exists at the weld seam, and the joint can be made more beautiful through subsequent grinding. Figure 10 The scanning diagram of the welding interface after welding for Comparative Example 1 is shown. There are black continuous interface oxides at the interface, not meeting the requirements of the technical solution of the present invention. This is because the welding time is short, resulting in no time for the interface oxides to decompose. Figure 11 The transmission diagram of the welding interface after welding for Example 1 is shown. There are no large-sized interface oxides at the welding interface, and no severely coarsened nano-oxides are found. The initial welding interface disappears, indicating that metallurgical bonding has been achieved. Figure 12It is the macroscopic view of the welding interface of Comparative Example 2. The welding interface presents a black linear shape, indicating the existence of continuous large-size interfacial oxides, which does not meet the requirements of the technical solution of the present invention. This is due to the small electrode pressure, which is not conducive to the fragmentation and decomposition of the interfacial oxides. Figure 13 It is the macroscopic view of the welding interface of Example 6. The welding interface achieves metallurgical bonding, and no large-size interfacial oxides are found, and the joint quality is good.

[0089] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. The present invention extends to any new feature or any new combination disclosed in this specification, as well as any new method or process step or any new combination disclosed.

Claims

1. A pressure resistance welding device for thin-walled parts of ODS steel T-joints, characterized in that: It includes an upper electrode, a lower electrode, a fixture, and a copper spacer; a groove penetrating the cross-section is provided at the top end of the lower electrode; the fixture is installed above the lower electrode, a limiting groove corresponding to the top end of the lower electrode is provided at the bottom of the fixture, a reserved groove communicating with the limiting groove is provided on the top surface of the fixture, a limiting block is convexly provided on the inner side surface of the limiting groove and outside the reserved groove, and the limiting block is used to insert into the groove on the lower electrode to limit and fix the welding component A, and the reserved groove is used to limit and fix the welding component B and the copper spacer; the copper spacer is arranged in the reserved groove of the fixture, the upper surface of the copper spacer contacts the lower surface of the upper electrode, and the lower surface of the copper spacer contacts the upper surface of the welding component B, which is used to press the welding component A and the welding component B, the outer contour shape of the copper spacer matches the reserved groove, and the height of the copper spacer above the upper surface of the fixture is greater than or equal to 1 mm.

2. The pressure resistance welding device for the thin-walled part of the ODS steel T-joint according to claim 1, characterized in that: The groove on the lower electrode matches the welding component A in shape, and the reserved groove on the fixture matches the welding component B in shape.

3. The pressure resistance welding device for thin-walled parts of ODS steel T-joints according to claim 1, characterized in that: The lower electrode is composed of two materials, copper alloy and bakelite; the bakelite is embedded in the upper layer of the copper alloy to form a bakelite layer and a copper alloy layer, and the shape of the bakelite layer matches the position where the lower electrode contacts the fixture, which is used to isolate the current conduction with the fixture.

4. A method for pressure resistance welding of thin-walled parts of ODS steel T-joints, characterized in that, It includes the following steps: (1) Clean the welding components A and B required for welding the thin-walled T-joint, and then dry them; (2) Raise the upper electrode of the pressure resistance welding device according to claim 1, insert the welding component A into the middle position of the groove of the lower electrode, install the fixture on the lower electrode, then put the welding component B into the reserved groove of the fixture, place the copper spacer, and lower the upper electrode until it contacts the upper surface of the copper spacer; (3) Set the resistance welding process parameters to achieve welding, and the welding parameters include welding current, welding time, and electrode pressure.

5. The method for pressure resistance welding of thin-walled parts of ODS steel T-joints according to claim 4, characterized in that: The thin-walled T-joint is formed by welding the welding components A and B. The welding component A is a rectangular structural part with a predetermined thickness, and the thickness dimension of the welding component A is equal to the width of the groove at the top end of the lower electrode. The length direction of the welding component A is 0.2 - 0.5 mm higher than the upper surface of the lower electrode. The welding component B is also a rectangular structural part with a predetermined thickness, and a convex platform with a height of 0.2 - 0.5 mm is provided at the position corresponding to the welding component A. The thicknesses of the welding components A and B are 0.3 - 3 mm.

6. The method for pressure resistance welding of thin-walled parts of ODS steel T-joints according to claim 4, characterized in that At the welding interface of the ODS steel T-joint prepared by the pressure resistance welding method, the size of the oxide is ≤0.5 μm, and nano-oxides are diffusely distributed in the deformation zone of the welding interface, and the size of the nano-oxide particles is ≤50 nm.

7. The pressure resistance welding method for the thin-walled member of the ODS steel T-joint according to claim 4, characterized in that: The welding process parameters in step (3) are: welding current 2.0 - 10.6 kA, welding time 12 - 59 ms, and electrode pressure 1 - 5.5 kN.

8. The pressure resistance welding method for the thin-walled part of the ODS steel T-joint according to claim 4, characterized in that When the thickness of the welding material is less than or equal to 1 mm, the welding process parameters are as follows: welding current 2 - 5 kA, welding time 11 - 32 ms, electrode pressure 1 - 2.5 kN; the preferred welding process parameters are: welding current 2 - 3 kA, welding time 25 - 32 ms, electrode pressure 1 - 1.5 kN; or set as: welding current 3 - 4 kA, welding time 18 - 25 ms, electrode pressure 1.5 - 2 kN; or set as: welding current 4 - 5 kA, welding time 11 - 18 ms, electrode pressure 2 - 2.5 kN.

9. The pressure resistance welding method for the thin-walled member of the ODS steel T-joint according to claim 4, characterized in that, When the thickness of the welding material is 1 - 2 mm, that is, 1 mm < thickness ≤ 2 mm, the welding process parameters are as follows: welding current 4.8 - 7.8 kA, welding time 25 - 46 ms, electrode pressure 2.5 - 4 kN; the preferred welding process parameters are: welding current 4.8 - 5.8 kA, welding time 39 - 46 ms, electrode pressure 2.5 - 3 kN; or set as: welding current 5.8 - 6.8 kA, welding time 32 - 39 ms, electrode pressure 3 - 3.5 kN; or set as: welding current 6.8 - 7.8 kA, welding time 25 - 32 ms, electrode pressure 3.5 - 4 kN.

10. The pressure resistance welding method for the thin-walled part of the ODS steel T-joint according to claim 4, characterized in that, When the thickness of the welding material is 2 - 3 mm, that is, 2 mm < thickness ≤ 3 mm, the welding process parameters are as follows: welding current 7.6 - 10.6 kA, welding time 38 - 59 ms, electrode pressure 4 - 5.5 kN; the preferred welding process parameters are: welding current 7.6 - 8.6 kA, welding time 52 - 59 ms, electrode pressure 4 - 4.5 kN; or set as: welding current 8.6 - 9.6 kA, welding time 45 - 52 ms, electrode pressure 4.5 - 5 kN; or set as: welding current 9.6 - 10.6 kA, welding time 38 - 45 ms, electrode pressure 5 - 5.5 kN.

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