High absolute Seebeck coefficient dissimilar material electron beam welding method and application thereof

Abstract

This invention provides a method for electron beam welding of dissimilar materials with high absolute Seebeck coefficients and its application. The method includes: annealing the dissimilar materials and cooling them to room temperature; grinding the annealed dissimilar materials to achieve a 4-8° inclination angle at the mating surfaces; demagnetizing the pre-processed dissimilar materials and pre-treating the mating surfaces between them; fitting the mating surfaces of the pre-processed dissimilar materials together to complete the welding assembly; and positioning the electron beam at the center of the weld to perform electron beam welding. The electron beam welding method for dissimilar materials with high absolute Seebeck coefficients provided by this invention enables one-time welding, reduces manufacturing costs, improves the mechanical properties of welded joints between dissimilar materials with high absolute Seebeck coefficients, and ensures that the welded joint quality meets Class I weld requirements, achieving a high-quality connection between dissimilar materials with high absolute Seebeck coefficients.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electron beam welding, in particular to a high-absolute-Schebeck-coefficient dissimilar material electron beam welding method and application thereof. BACKGROUND

[0002] As a kind of high-efficiency liquid rocket engine, hydrogen-oxygen engine has the advantages of high chemical energy, environmental protection, high cooling, etc., which is an important direction for the development of aerospace. Thrust chamber is an important component in hydrogen-oxygen engine, which bears the impact of high-temperature and high-pressure gas during operation, and needs to be welded by dissimilar materials during preparation. Electron beam welding method has the advantages of precise controllable energy density and providing high vacuum protection environment, which can avoid the deformation of dissimilar materials during welding and is suitable for welding of dissimilar materials.

[0003] However, the dissimilar joint composed of dissimilar materials usually has a large absolute Seebeck coefficient, which will generate a large inductive magnetic field during electron beam welding, especially when the welding thickness is greater than or equal to 5mm, which will cause the deflection of electron beam, and further produce un-melted defects at the root of the weld, which will cause the thrust chamber to fail during operation, and even cause the engine to be scrapped. At present, in order to solve the above problems, the conventional method is to carry out secondary and tertiary repair welding, but multiple repair welding will introduce a large amount of welding heat input, which will further cause the mechanical properties of the joint to decrease, and it is difficult to meet the use requirements of aerospace engines. Therefore, electron beam welding of dissimilar materials with high absolute Seebeck coefficient is a bottleneck problem in the manufacturing process of aerospace hydrogen-oxygen engine. SUMMARY

[0004] The problem solved by the present application is to provide an electron beam welding method capable of eliminating the un-melted defects at the root of the electron beam weld of dissimilar materials with high absolute Seebeck coefficient, improving the mechanical properties of the welded joint, and realizing high-quality connection between dissimilar materials with high absolute Seebeck coefficient.

[0005] To solve the above problems, the present application provides a high-absolute-Schebeck-coefficient dissimilar material electron beam welding method, comprising the following steps:

[0006] Step S1, annealing heat treatment is performed on the dissimilar materials, and the dissimilar materials are cooled to room temperature to obtain annealed dissimilar materials;

[0007] Step S2, grinding processing is performed on the annealed dissimilar materials, so that the inclination angle of the butt joint surface of the annealed dissimilar materials is 4-8°, to obtain pre-processed dissimilar materials;

[0008] Step S3, demagnetization treatment is performed on the pre-processed dissimilar materials, and the butt joint surface between the pre-processed dissimilar materials is pretreated to obtain pretreated dissimilar materials;

[0009] Step S4, the butt joint surface of the pre-processed dissimilar materials is adhered, and the welding assembly between the pre-processed dissimilar materials is completed.

[0010] Step S5, the electron beam is positioned at the center of the welding seam of the dissimilar materials, and the electron beam welding is performed.

[0011] Preferably, in the step S1, the dissimilar materials are subjected to annealing heat treatment, the temperature of the annealing heat treatment is higher than the Curie point of the dissimilar materials, and the time is not less than 2h, and after cooling to room temperature, the annealed dissimilar materials are obtained.

[0012] Preferably, in the step S3, the pre-processed dissimilar materials are subjected to demagnetization treatment by using an alternating demagnetization machine, so that the residual magnetism of the pre-processed dissimilar materials is less than or equal to 3 Gauss.

[0013] Preferably, in the step S3, alcohol and acetone are used to pre-treat the butt joint surface between the pre-processed dissimilar materials.

[0014] Preferably, in the step S4, the long side of the high Seebeck coefficient material and the short side of the low Seebeck coefficient material in the pre-processed dissimilar materials are positioned at the front of the welding seam, so that the butt joint surface of the pre-processed dissimilar materials is adhered, and the welding assembly between the pre-processed dissimilar materials is completed.

[0015] Preferably, the assembly gap between the high Seebeck coefficient material and the low Seebeck coefficient material is less than or equal to 0.01mm.

[0016] Preferably, in the step S5, the electron beam is positioned at the center of the welding seam of the dissimilar materials by using surface focusing, the acceleration voltage is 55kV, the focusing current is 2490mA, and the positioning beam current is 2mA.

[0017] Preferably, in the step S5, the parameters of the electron beam welding are set as follows: the acceleration voltage is 55kV, the focusing current is 2490mA, the welding current is 28mA, and the welding speed is 600mm / min.

[0018] Preferably, at least one of the dissimilar materials is a ferromagnetic material.

[0019] The application realizes the adjustment of the melting ratio of the high Seebeck coefficient material and the low Seebeck coefficient material in the subsequent electron beam welding process by grinding the dissimilar materials to make the butt joint surface of the dissimilar materials have an inclination angle of 4-8°, eliminates the defect of the electron beam weld root unmelting in the electron beam welding process of the high absolute Seebeck coefficient dissimilar materials, can realize one-time forming of welding, reduces the manufacturing cost, improves the mechanical properties of the welded joint between the high absolute Seebeck coefficient dissimilar materials, makes the quality of the welded joint meet the requirements of the I-grade weld, realizes the high-quality connection between the high absolute Seebeck coefficient dissimilar materials, performs the annealing treatment and demagnetization treatment of the dissimilar materials above the Curie point, reduces the influence of the residual magnetism on the electron beam deflection in the electron beam welding process, and the pretreatment of the butt joint surface of the dissimilar materials can remove the impurities on the butt joint surface and ensure the welding quality.

[0020] In another aspect, the application also provides an application of the high absolute Seebeck coefficient dissimilar material electron beam welding method, which is applied to the field of hydrogen-oxygen generator manufacturing.

[0021] The application of the high absolute Seebeck coefficient dissimilar material electron beam welding method to the field of hydrogen-oxygen generator manufacturing can improve the joint welding quality of the dissimilar materials in the hydrogen-oxygen generator, improve the yield of the hydrogen-oxygen generator manufacturing, and reduce the manufacturing cost. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a flowchart of the high absolute Seebeck coefficient dissimilar material electron beam welding method in the embodiment of the application.

[0023] Figure 2 It is an assembly relationship diagram of the dissimilar materials in embodiment 1 of the application.

[0024] Figure 3 It is an assembly relationship diagram of the dissimilar materials in comparative example 1.

[0025] Figure 4 It is a metallographic analysis diagram of the dissimilar material welded joint in embodiment 1 of the application.

[0026] Figure 5 It is a metallographic analysis diagram of the dissimilar material welded joint in comparative example 1. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the specific embodiments of the application are described in detail below.

[0028] It should be noted that, unless otherwise specified, the features in the embodiments of this invention can be combined with each other. The terms "comprising," "including," "containing," and "having" are non-limiting, meaning that other steps and other components that do not affect the results can be added. The above terms cover the terms "composed of" and "substantially composed of." Unless otherwise specified, the materials, equipment, and reagents are commercially available.

[0029] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0030] In the description of this specification, references to terms such as "embodiment," "one embodiment," and "one implementation" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or implementation is included in at least one embodiment or illustrative implementation of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or implementation. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or implementations.

[0031] This invention provides a method for electron beam welding of dissimilar materials with a high absolute Seebeck coefficient, such as... Figure 1 As shown, it includes the following steps:

[0032] Step S1: Anneal the dissimilar material and cool it to room temperature to obtain the annealed dissimilar material;

[0033] Step S2: Grind the annealed dissimilar material to make the inclination angle of the mating surface of the annealed dissimilar material 4-8°, and obtain the pre-processed dissimilar material;

[0034] Step S3: Demagnetize the pre-processed dissimilar materials and pre-treat the mating surfaces between the pre-processed dissimilar materials to obtain pre-treated dissimilar materials;

[0035] Step S4: Fit the mating surfaces of the pretreated dissimilar materials together to complete the welding assembly between the pretreated dissimilar materials;

[0036] Step S5: Position the electron beam at the center of the weld seam of the dissimilar materials and perform electron beam welding.

[0037] It should be noted that, in the embodiments of the present invention, dissimilar materials with high absolute Seebeck coefficients refer to materials with a Seebeck coefficient difference of less than 1×10⁻⁶. -5 Dissimilar materials with a V / K ratio greater than 1. For example, GH4169 and electroformed Ni are dissimilar materials with high absolute Seebeck coefficients.

[0038] In addition, at least one of the dissimilar materials is a ferromagnetic material.

[0039] In step S1, annealing the dissimilar materials improves the welding quality in the subsequent electron beam welding process. Further, the dissimilar materials are annealed at a temperature exceeding the Curie point for at least 2 hours, and then cooled to room temperature to obtain the annealed dissimilar material. Annealing above the Curie point reduces the spontaneous magnetization in the material and eliminates remanence.

[0040] In step S2, the annealed dissimilar materials are ground to achieve an inclination angle of 4-8° on the mating surfaces, resulting in pre-processed dissimilar materials. When the inclination angle of the mating surfaces is less than 4° or exceeds 8°, incomplete fusion defects during electron beam welding cannot be completely eliminated.

[0041] It should be noted that the tilt angle of the mating surfaces of dissimilar materials is related to the properties of the dissimilar materials themselves, especially the difference in Seebeck coefficients, and can be adjusted according to the properties of the dissimilar materials.

[0042] For example, when the initial mating surface of dissimilar materials is perpendicular to the upper and lower surfaces, the mating surface of the dissimilar materials is ground so that the angle between the machined inclined surface and the initial mating surface is 4-8°, and the pre-machined dissimilar materials have long sides and short sides formed on the upper and lower surfaces respectively.

[0043] In step S3, demagnetizing the pre-processed dissimilar material further eliminates its residual magnetism and reduces its influence on electron beam deflection. Specifically, a TC2 alternating demagnetizer is used to demagnetize the pre-processed dissimilar material, ensuring that its residual magnetism is less than or equal to 3 Gauss. Controlling the residual magnetism of the dissimilar material below 3 Gauss avoids incomplete fusion defects caused by electron beam deflection during electron beam welding.

[0044] Pre-treatment is performed on the mating surfaces of dissimilar materials. Specifically, alcohol and acetone are used to clean the mating surfaces of the dissimilar materials to make the surfaces smooth and free of oil and water, so that the dissimilar materials can fit together well and the impact of impurities on the welding quality is reduced.

[0045] In step S4, the long side of the material with the high Seebeck coefficient and the short side of the material with the low Seebeck coefficient in the pretreated dissimilar materials are placed on the front of the weld, so that the mating surfaces of the pretreated dissimilar materials fit together, and the welding assembly between the pretreated dissimilar materials is completed.

[0046] During electron beam welding, the electron beam deflects towards the side with higher thermoelectric potential. By using the above assembly method, the thermal action area of ​​the electron beam on the low Seebeck coefficient material can be increased during electron beam welding, thereby increasing the melting amount of the low Seebeck coefficient material. In this way, the fusion ratio of high Seebeck coefficient material and low Seebeck coefficient material can be controlled, solving the incomplete fusion defect caused by the deflection of the electron beam towards the high Seebeck coefficient material due to the magnetic field during electron beam welding of dissimilar materials with high absolute Seebeck coefficient.

[0047] During assembly, the assembly gap between the high Seebeck coefficient material and the low Seebeck coefficient material is less than or equal to 0.01 mm. Controlling the assembly gap to below 0.01 mm allows the two materials to fully bond together during electron beam welding, improving the quality of the weld joint.

[0048] In step S5, surface focusing is used, with an accelerating voltage of 55kV, a focusing current of 2490mA, and a positioning beam current of 2mA. The electron beam is positioned at the center of the weld seam of the dissimilar materials. The parameters for electron beam welding are set as follows: accelerating voltage 55kV, focusing current 2490mA, welding current 28mA, and welding speed 600mm / min.

[0049] That is, firstly, surface focusing is used to position the electron beam at the center of the weld seam of dissimilar materials, and then electron beam welding of dissimilar materials with high absolute Seebeck coefficient is performed using parameters of 55kV acceleration voltage, 2490mA focusing current, 28mA welding current, and 600mm / min welding speed.

[0050] Another embodiment of the present invention provides an application of the electron beam welding method for dissimilar materials with high absolute Seebeck coefficient, applying the electron beam welding method for dissimilar materials with high absolute Seebeck coefficient as described above to the field of hydrogen-oxygen generator manufacturing.

[0051] By applying the aforementioned high absolute Seebeck coefficient electron beam welding method for dissimilar materials to the field of hydrogen-oxygen generator manufacturing, the joint welding quality of dissimilar materials in hydrogen-oxygen generators can be improved, the yield rate of hydrogen-oxygen engine manufacturing can be increased, and the manufacturing cost can be reduced.

[0052] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to the conditions recommended by the manufacturer.

[0053] Example 1

[0054] In this embodiment, the welding objects are GH4169 material and electroformed Ni material. Both GH4169 material and electroformed Ni material are flat materials, and their initial mating surfaces are perpendicular. The specific steps are as follows:

[0055] 1.1 GH4169 material was subjected to solution treatment and double aging heat treatment. The temperature was increased to 960℃ at a heating rate of 20℃ / min, held for 2 hours, and then air-cooled to room temperature. Then the temperature was increased to 720℃ at a heating rate of 20℃ / min, and then decreased to 620℃ at a cooling rate of 50℃ / h. After holding for 8 hours, the material was air-cooled. Electroformed Ni material (Curie point 358℃) was heated to 280℃ at a heating rate of 15℃ / min, held, and then air-cooled to room temperature.

[0056] 1.2. Using grinding, inclined mating surfaces are machined on GH4169 material and electroformed Ni material respectively, so that the angle between the inclined mating surface and the initial vertical mating surface is 4°.

[0057] 1.3. The electroformed Ni was demagnetized using a TC2 alternating demagnetizer to achieve a remanence of ≤3 Gauss.

[0058] 1.4. Use alcohol and acetone to clean the surfaces of GH4169 material and electroformed Ni material to remove oil and water.

[0059] 1.5, such as Figure 2 As shown, the long side of GH4169 material and the short side of electroformed Ni material are placed on the front of the weld, and the mating surfaces of GH4169 material and electroformed Ni material are made to fit together to ensure that the maximum assembly gap is ≤0.01mm;

[0060] 1.6. Surface focusing was used, with an accelerating voltage of 55kV, a focusing current of 2490mA, and a positioning beam current of 2mA. The electron beam was positioned at the center of the weld. The electron beam welding parameters were set as follows: accelerating voltage 55kV, focusing current 2490mA, welding current 28mA, and welding speed 600mm / min. Electron beam welding of GH4169 material and electroformed Ni material was completed.

[0061] Comparative Example 1

[0062] In this embodiment, the welding objects are GH4169 material and electroformed Ni material. Both GH4169 material and electroformed Ni material are flat materials, and their initial mating surfaces are perpendicular. The specific steps are as follows:

[0063] 2.1 GH4169 material underwent solution treatment and double aging heat treatment. The temperature was increased to 960℃ at a heating rate of 20℃ / min, held for 2 hours, and then air-cooled to room temperature. Then, the temperature was increased to 720℃ at a heating rate of 20℃ / min, and then decreased to 620℃ at a cooling rate of 50℃ / h. After holding for 8 hours, the material was air-cooled. Electroformed Ni material (Curie point 358℃) was heated to 280℃ at a heating rate of 15℃ / min, held, and then air-cooled to room temperature.

[0064] 2.2. The electroformed Ni was demagnetized using a TC2 alternating demagnetizer to achieve a remanence of ≤3 Gauss.

[0065] 2.3. Use alcohol and acetone to clean the surfaces of GH4169 material and electroformed Ni material to remove oil and water.

[0066] 2.4, such as Figure 3 As shown, the perpendicular mating surfaces of GH4169 material and electroformed Ni material are bonded together to ensure that the maximum assembly gap is ≤0.01mm;

[0067] 2.5. Surface focusing was used, with an accelerating voltage of 55kV, a focusing current of 2490mA, and a positioning beam current of 2mA. The electron beam was positioned at the center of the weld. The electron beam welding parameters were set as follows: accelerating voltage 55kV, focusing current 2490mA, welding current 28mA, and welding speed 600mm / min. Electron beam welding of GH4169 material and electroformed Ni material was completed.

[0068] Experimental Example

[0069] X-ray flaw detection was performed on the welded joints obtained by the electron beam welding method in Example 1 and Comparative Example 1, and the weld cross-section was inspected for defects using an optical microscope.

[0070] The results are as follows Figure 4 and Figure 5 As shown, where, Figure 4 The image shown is a metallographic analysis diagram of the welded joint obtained in Example 1. Figure 4 Image (a) is a magnified view of the weld in Example 1, magnified 100 times. Figure 4 Image (b) is a magnified view of the weld root in Example 1, magnified 1000 times. Figure 5 The image shows the metallographic analysis of the welded joint obtained in Comparative Example 1. Figure 5 Image (a) is a magnified view of the weld in Comparative Example 1, magnified 100 times. Figure 5 (b) is a magnified view of the weld root in Comparative Example 1, magnified 1000 times.

[0071] like Figure 4As shown, no lack of fusion defects were found at the weld root in Example 1, and the weld quality met the Class I joint standard; Figure 5 As shown, in Comparative Example 1, incomplete fusion defects were found at the weld root, and the overall weld quality was low. This is mainly because Example 1, by designing a butt joint with an inclined angle, achieved adjustment of the melting ratio between materials with high and low Seebeck coefficients, eliminating incomplete fusion defects at the electron beam weld root. Furthermore, it eliminated the need for multiple welding operations, reducing manufacturing costs, improving the mechanical properties of the joint, and enabling the joint quality to meet Class I weld requirements, thus achieving a high-quality connection of dissimilar materials.

[0072] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A method for electron beam welding of dissimilar materials with high absolute Seebeck coefficient, characterized in that, Includes the following steps: Step S1: The dissimilar material is subjected to annealing heat treatment and cooled to room temperature to obtain annealed dissimilar material; wherein, the annealing heat treatment temperature exceeds the Curie point of the dissimilar material, the time is not less than 2 hours, and after cooling to room temperature, the annealed dissimilar material is obtained. Step S2: Grind the annealed dissimilar material to make the inclination angle of the mating surface of the annealed dissimilar material 4-8°, and obtain the pre-processed dissimilar material; Step S3: Demagnetize the pre-processed dissimilar materials and pre-treat the mating surfaces between the pre-processed dissimilar materials to obtain pre-treated dissimilar materials; wherein, an alternating demagnetizer is used to demagnetize the pre-processed dissimilar materials so that the residual magnetism of the pre-processed dissimilar materials is less than or equal to 3 Gauss. Step S4: Place the long side of the material with the high Seebeck coefficient and the short side of the material with the low Seebeck coefficient in the pretreated dissimilar materials on the front of the weld, so that the mating surfaces of the pretreated dissimilar materials fit together, and complete the welding assembly between the pretreated dissimilar materials. Step S5: First, use surface focusing to position the electron beam at the center of the weld seam of dissimilar materials, and then use parameters of 55kV acceleration voltage, 2490mA focusing current, 28mA welding current, and 600mm / min welding speed for electron beam welding.

2. The electron beam welding method for dissimilar materials with high absolute Seebeck coefficient according to claim 1, characterized in that, In step S3, alcohol and acetone are used to pre-treat the mating surfaces between the pre-processed dissimilar materials.

3. The electron beam welding method for dissimilar materials with high absolute Seebeck coefficient according to claim 1, characterized in that, The assembly gap between the high Seebeck coefficient material and the low Seebeck coefficient material is less than or equal to 0.01 mm.

4. The electron beam welding method for dissimilar materials with high absolute Seebeck coefficient according to claim 1, characterized in that, At least one of the dissimilar materials is a ferromagnetic material.

5. An application of an electron beam welding method for dissimilar materials with a high absolute Seebeck coefficient, characterized in that, The application of the electron beam welding method for dissimilar materials with high absolute Seebeck coefficient as described in any one of claims 1-4 in the field of hydrogen-oxygen generator manufacturing.

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