Composite welding method of austenitic stainless steel plate

Abstract

The invention relates to the field of welding processing technology of steel, and discloses a composite welding method of an austenitic stainless steel plate, which comprises the following steps: step 1, preparing two plate materials, and processing the end part of each plate material to form a U-shaped groove and an I-shaped groove; secondly, the groove ends of the two plate materials are assembled to form an assembly body, and the I-shaped grooves of the two plate materials are arranged in an attached mode; 3, the assembly is placed in a working chamber, the assembly is heated to a preset temperature, and the working chamber is vacuumized to a preset vacuum degree; fourthly, the assembly is welded through electron beam welding; 5, machining the excess weld metal of an electron beam welding seam, and enabling the transition position of the U-shaped groove and the I-shaped groove to be in smooth transition; and sixthly, filler wire welding is conducted on the U-shaped groove of the assembly. Therefore, the two plates are welded through the welding method combining electron beam welding and wire filling welding, the welding requirement for the plates with the large thickness (such as the plates with the thickness larger than 160 mm) can be met, and the welding efficiency and the welding seam quality are improved.

Description

Technical Field

[0001] The present application relates to the field of steel welding processing technology, and in particular to a composite welding method for austenitic stainless steel plates. Background Art

[0002] At present, austenitic stainless steel is widely used in petroleum, chemical industry, nuclear power, fusion reactor and other fields due to its excellent corrosion resistance and high strength. A large number of equipment use thick austenitic stainless steel plates as supporting structures, and the plate thickness is generally greater than 80mm. To achieve the welding of such thick austenitic stainless steel plates, it is necessary to overcome the difficulties of large welding deformation, easy cracking, complex process and low operating efficiency.

[0003] In the related art, thick stainless steel plates are usually welded by manual argon arc welding, metal electrode gas shielded welding, laser wire welding, laser welding and vacuum electron beam welding.

[0004] Among them, the greater the thickness of the stainless steel plate, the greater the difficulty of welding. In some schemes, in order to improve the quality of the weld, austenitic stainless steel is welded by laser welding combined with laser wire welding. However, laser welding requires double-sided welding when welding thick stainless steel plates with higher plate thickness, so quality defects are prone to occur at the double-sided weld positions and are difficult to remedy. Summary of the invention

[0005] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present application is to propose a composite welding method for austenitic stainless steel plates, which can improve welding efficiency and weld quality and achieve efficient welding of austenitic stainless steel plates.

[0006] The composite welding method of austenitic stainless steel plates according to the embodiment of the present application includes the following steps: step 1: preparing two sheets, and the end of each sheet is processed to form a U-shaped groove and an I-shaped groove; step 2: assembling the groove ends of the two sheets to form an assembly, and the I-shaped grooves of the two sheets are arranged in a fitting manner; step 3: placing the assembly in a working room, and heating the assembly to a preset temperature, and evacuating the working room to a preset vacuum degree; step 4: welding the assembly by electron beam welding; step 5: processing the electron beam welding weld excess height formed by electron beam welding, and smoothly transitioning the transition position of the U-shaped groove and the I-shaped groove; step 6: performing filler wire welding on the U-shaped groove of the assembly.

[0007] According to some embodiments of the present application, step two also includes: fixing a gasket on a side of the assembly away from the U-shaped groove, and respectively assembling an arc starting plate and an arc ending plate at both ends of the I-shaped groove.

[0008] According to some embodiments of the present application, the composite welding method of austenitic stainless steel plates further includes step seven: removing the gasket fixed to the assembly and cleaning the surface of the laser filler wire welding seam of the filler wire welding.

[0009] According to some embodiments of the present application, in step 3, the preset temperature is above 100°C, and the preset vacuum degree is lower than 5×10 -2 Pa.

[0010] According to some embodiments of the present application, in the step four, welding the assembly by electron beam welding includes: performing electron beam positioning welding on the I-groove of the assembly with first preset parameters, and the focal position is the surface focus; performing electron beam welding on the assembly along the weld of the electron beam positioning welding with second preset parameters, and the focal position is the lower focus.

[0011] According to some embodiments of the present application, the first preset parameters include: using a beam intensity of 5mA-15mA, a surface moving speed of 3mm / s, a voltage of 150kV, and a working distance of 600mm-1000mm; the second preset parameters include: using a beam intensity of 180mA-230mA, a surface moving speed of 3mm / s, a voltage of 150kV, and a working distance of 600mm-1000mm.

[0012] According to some embodiments of the present application, after the assembly is welded by electron beam welding in step 4, the step further includes: cooling the assembly in the working room for a preset time.

[0013] According to some embodiments of the present application, the preset time is not less than 12 hours.

[0014] According to some embodiments of the present application, the filler wire welding process in step six is ​​one of a laser filler wire welding process and a submerged arc welding process.

[0015] According to some embodiments of the present application, the thickness of the sheet is L, and satisfies the relationship: L≥80mm; and / or, the thickness of each sheet at the U-shaped groove is L1, and satisfies the relationship: L1≥30mm; and / or, the thickness of each sheet at the I-shaped groove is L2, and satisfies the relationship: L2≥50mm.

[0016] In summary, the composite welding method of austenitic stainless steel plates according to the embodiment of the present application has at least the following advantages compared with the prior art: (1) The hybrid welding method of electron beam welding combined with laser wire welding can achieve the welding of austenitic stainless steel sheets with a thickness of more than 160 mm; (2) Vacuum electron beam welding is used to weld the sheet metal at the I-type groove. There is no need for multi-layer and multi-pass welding, which can improve welding efficiency. Vacuum electron beam welding can avoid the impact of multiple heat inputs and improve the quality of weld joints. There is no need to fill the deposited metal, which saves welding materials and reduces welding costs. At the same time, vacuum electron beam welding has low line energy, fast welding speed, and small welding deformation.

[0017] (3) Laser wire welding is used to complete the welding of the assembly at the U-shaped groove, with small heat input and deformation and excellent weld quality.

[0018] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 is a schematic diagram of assembling two panels according to an embodiment of the present application; Figure 2 It is a schematic diagram of the coordination of the sheet material, the liner, the arc starting plate and the arc ending plate according to one embodiment of the present application; Figure 3 It is a schematic diagram of an electron beam welding seam and a laser wire welding seam according to an embodiment of the present application; Figure 4 is an electron beam welding weld diagram according to an embodiment of the present application; Figure 5 It is a microscopic metallographic test result according to one embodiment of the present application; Figure 6 is a tensile test result according to one embodiment of the present application; Figure 7 is a bending test result according to one embodiment of the present application; Figure 8 is an impact test result according to an embodiment of the present application; Fig. 9 It is a flow chart of a composite welding method according to one embodiment of the present application.

[0020] Reference numerals: Sheet material 1; I-shaped groove 2; U-shaped groove 3; gasket 4; arc starting plate 51; arc closing plate 52; electron beam welding seam 6; laser wire filling welding seam 7. DETAILED DESCRIPTION

[0021] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0022] Reference below Figure 1-Figure 9 A composite welding method for an austenitic stainless steel plate according to an embodiment of the present application is described. The composite welding method can be applied to the welding of austenitic stainless steel plates to improve welding efficiency and weld quality and achieve efficient welding of austenitic stainless steel plates.

[0023] Specifically, the composite welding method includes at least the following steps: Step 1: prepare two sheets 1, and the end of each sheet 1 is processed to form a U-shaped groove 3 and an I-shaped groove 2; Step 2: assemble the groove ends of the two sheets 1 to form an assembly, and the I-shaped grooves 2 of the two sheets 1 are arranged in a close fit; Step 3: place the assembly in a working room, and heat the assembly to a preset temperature, and evacuate the working room to a preset vacuum degree; Step 4: weld the assembly by electron beam welding; Step 5: process the excess height of the electron beam welding weld 6 formed by electron beam welding, and smoothly transition the transition position of the U-shaped groove 3 and the I-shaped groove 2; Step 6: perform wire welding at the U-shaped groove 3 of the assembly.

[0024] Reference Figure 1 As shown, two sheets 1 are prepared in the welding process, each of which is a stainless steel sheet made of austenitic stainless steel, and the welding ends of the two sheets 1 are processed to form a U-shaped groove 3 and an I-shaped groove 2. When the two sheets 1 need to be arranged in a welding matching position, the I-shaped grooves 2 of the two sheets 1 are arranged in a close fit, that is, there is no gap between the I-shaped grooves 2 of the two sheets 1, so as to improve the tightness of the matching between the two sheets 1, and the two sheets 1 are matched to form an assembly.

[0025] Furthermore, the assembly is arranged in a working room and heated by a heating device to make the assembly reach a preset temperature, and then the vacuum degree of the working room is further adjusted to a preset vacuum degree by vacuuming to prepare for subsequent electron beam welding of the assembly.

[0026] It should be noted that the above-mentioned "studio" refers to a storage space for arranging an assembly, and in this storage space, functions such as heating the assembly and adjusting the vacuum degree can be realized, and electron beam welding operations can be performed on the assembly.

[0027] Among them, in the electron beam welding process, the two plates 1 can meet the welding requirements by only tightly fitting at the I-type groove 2, reducing the need to open a groove in the plate 1, and can significantly reduce the amount of welding materials, reduce costs and save welding time, thereby improving welding efficiency.

[0028] After the assembly is processed by the electron beam welding process, the electron beam welding weld 6 formed by the electron beam welding can be processed so that the assembly can have a smooth transition in the adjacent transition area between the I-shaped groove 2 and the U-shaped groove 3, so as to facilitate the wire filling welding at the U-shaped groove 3 of the assembly and ensure the welding effect of the assembly at the U-shaped groove 3.

[0029] It can be understood that the above-mentioned processing method for the excess height of the electron beam welding weld 6 formed by electron beam welding can be mechanical processing, and specifically can be processed by processing techniques such as milling. The processing method is not limited here. It is sufficient to be able to process the excess height of the electron beam welding weld 6 and achieve a smooth transition between the adjacent areas of the U-shaped groove 3 and the I-shaped groove 2.

[0030] Therefore, in the welding process of the austenitic stainless steel plate, the two plates 1 are first welded by electron beam welding, and the assembly is further welded by wire welding (such as laser wire welding), so that the welds of the two plates 1 (including electron beam welding welds 6 and laser wire welding welds 7) have narrow heat-affected zones, fine grain structures of the welds and heat-affected zones, and excellent joint performance. In other words, by combining the two welding processes, the processing requirements for the groove when welding the plate 1 can be reduced, and the welding efficiency can be improved.

[0031] It should be noted that, at present, stainless steel thick plates are usually welded by manual argon arc welding, metal arc welding, laser welding with wire, laser welding and vacuum electron beam welding. In the related technology, the thicker the stainless steel plate, the greater the difficulty of welding. In order to improve the quality of the weld, some schemes use laser welding combined with laser welding with wire to weld austenitic stainless steel. However, laser welding requires double-sided welding when welding thick stainless steel plates with high plate thickness, so quality defects are prone to occur at the double-sided weld position and are difficult to remedy, and thus cannot meet the welding needs of thicker stainless steel plates.

[0032] In the present application, during the welding process of two sheets 1 (austenitic stainless steel sheets), the two sheets 1 are first welded by electron beam welding, and then the assembly formed by the two sheets 1 is further filled with solder at the U-shaped groove 3 by wire welding and welded, thereby being able to meet the welding requirements of sheets 1 with thicker thickness (such as: thickness greater than 160 mm, etc.).

[0033] Specifically, by performing electron beam welding in a studio with a certain degree of vacuum, there is no need for multi-layer and multi-pass welding, which saves welding steps and improves welding efficiency. In addition, electron beam welding has low line energy, fast welding speed, and small welding deformation, which can ensure welding quality. At the same time, electron beam welding is more efficient than double-sided welding required by laser welding, and can avoid the influence of multiple heat inputs, thereby improving the quality of weld joints. At the same time, there is no need to fill the deposited metal between the two sheets 1, which can save welding materials.

[0034] Combination Figure 1 and Figure 2 As shown, in some embodiments of the present application, step two also includes: fixing a gasket 4 on the side of the assembly away from the U-shaped groove 3, and respectively assembling an arc starting plate 51 and an arc ending plate 52 at both ends of the I-shaped groove 2.

[0035] It is understandable that by arranging the gasket 4 on the assembly, it is possible to effectively prevent the back of the assembly (i.e., the side of the assembly away from the U-shaped groove 3) from welding leakage and collapse, thereby improving the reliability and safety of the welding process. At the same time, by arranging the arc starting plate 51 and the arc ending plate 52 at both ends of the I-shaped groove 2, the welding quality of the weld at the arc starting position and the arc ending position can be improved.

[0036] In a further embodiment of the present application, the hybrid welding method further includes step seven: removing the gasket 4 fixed to the assembly, and cleaning the surface of the laser filler wire welding seam 7 welded by the filler wire welding.

[0037] It is understandable that after the assembly is welded by filler wire welding, the welding operation of the assembly is completed, that is, the assembly does not need to be protected by the gasket 4, and the gasket 4 can be removed from the assembly to facilitate further cleaning of the laser filler wire welding seam 7 formed by the filler wire welding.

[0038] In some embodiments of the present application, in the above step 3, the preset temperature is above 100°C, and the preset vacuum degree is lower than 5×10 -2 Pa.

[0039] It should be noted that the preset temperature can be a range parameter, such as 100°C-150°C. When the preset temperature is within the above parameter range, the vacuum degree of the working chamber can be adjusted so that the vacuum degree of the vacuum chamber is lower than 5×10 - 2 Pa, to achieve vacuum electron beam welding of the assembly and improve the welding effect of the assembly at the I-groove 2.

[0040] In some embodiments of the present application, in step four, welding the assembly by electron beam welding further includes: performing electron beam positioning welding on the I-type groove 2 of the assembly with first preset parameters, and the focus position is the surface focus; performing electron beam welding along the weld of the assembly by electron beam positioning welding with second preset parameters, and the focus position is the lower focus.

[0041] That is to say, in the process of electron beam welding the assembly, there are two welding operations. First, the assembly is firstly subjected to electron beam tack welding with the first preset parameters, and the focus of the electron beam tack welding is located on the surface of the assembly, so as to position the two sheets 1; second, the positioned assembly is further subjected to electron beam welding with the second preset parameters to achieve the welding coordination of the two sheets 1 at the I-shaped groove 2, and the focus of the electron beam welding is the lower focus, which can ensure the welding depth of the electron beam welding and improve the welding effect of the two sheets 1 at the I-shaped groove 2.

[0042] In some embodiments of the present application, the first preset parameters include: using a beam intensity of 5mA-15mA, a surface movement speed of 3mm / s, a voltage of 150kV, and a working distance of 600mm-1000mm; the second preset parameters include: using a beam intensity of 180mA-230mA, a surface movement speed of 3mm / s, a voltage of 150kV, and a working distance of 600mm-1000mm.

[0043] The above-mentioned “surface moving speed” refers to the moving speed of the welding equipment relative to the assembly; the above-mentioned “working distance” refers to the distance between the output end of the equipment emitting the electron beam and the assembly.

[0044] In some embodiments of the present application, after the assembly is welded by electron beam welding in step 4, the step further includes: cooling the assembly in the working chamber for a preset time, thereby improving the microstructure and properties of the weld.

[0045] It can be understood that the composite welding method in the present application is suitable for thicker sheets 1. Since the welding thickness of the sheet 1 at the I-type groove 2 is relatively large, by slowly cooling the assembly in the vacuum environment formed in the studio, the grains can be refined, the weld microstructure performance can be improved, and the welding effect of electron beam welding on the assembly can be enhanced.

[0046] In a further embodiment of the present application, the preset time is not less than 12 hours, so that the assembly can be fully cooled.

[0047] The assembly can be cooled by natural cooling, and the cooling environment of the assembly is a studio, so that the assembly after electron beam welding is slowly cooled under a vacuum state, thereby improving the effect of grain refinement and improving weld microstructure performance.

[0048] In some embodiments of the present application, the filler wire welding process in step six is ​​one of a laser filler wire welding process and a submerged arc welding process to meet the welding requirements of the assembly at the U-shaped groove 3.

[0049] Among them, the laser wire-filling welding process refers to: adding welding wire during the laser welding process, so that the welding process has the high energy density and fast welding speed of the laser, and has the metallurgical reaction and molten pool formation of the arc, which helps to improve the weld performance; the submerged arc welding process refers to: melting the welding wire, flux and base metal and filling them between the workpieces through electric arc heating, and forming a weld after cooling to connect the workpieces together, and has the advantages of high welding efficiency, good welding quality, no arc light and less smoke.

[0050] In a specific embodiment of the present application, a laser wire-filling welding process is taken as an example. In the laser wire-filling welding process, the laser power is 4kw-7kw, the welding speed is 6mm / s-11mm / s, the defocus is 40mm-70mm, and N2 (nitrogen) is used as the shielding gas, the nitrogen concentration is ≥99.99%, the flow rate is 40L / min-70L / min, and a φ1.6mm austenitic stainless steel welding wire is used for laser wire-filling welding, and the wire feeding speed is 140cm / min-260cm / min. It should be noted that the laser wire-filling welding process is not limited to the above parameters, and the specific parameters can be adaptively adjusted according to actual welding requirements.

[0051] In some embodiments of the present application, the thickness of the sheet material 1 is L, and satisfies the relationship: L≥80 mm.

[0052] In some embodiments of the present application, the thickness of each sheet material 1 at the U-shaped groove 3 is L1, and satisfies the relationship: L1 ≥ 30 mm.

[0053] In some embodiments of the present application, the thickness of each sheet material 1 at the I-groove 2 is L2, and satisfies the relationship: L2 ≥ 50 mm.

[0054] The plate 1 to which the composite welding method of the embodiment of the present application is applied can simultaneously meet the above-mentioned multiple groups of parameters, for example: L is 160 mm, L1 is 60 mm, L2 is 100 mm, and so on.

[0055] It should be noted that the composite welding method of austenitic stainless steel plates according to the embodiment of the present application can meet the welding requirements of plates 1 with larger thickness (eg, L≥160 mm) by combining vacuum electron beam welding with laser wire welding.

[0056] In a specific embodiment of the application of the above-mentioned composite welding method: the beam intensity used in electron beam welding is 180-230mA, the surface movement speed is 3mm / s, the voltage is 150kV, the working distance is 600-1000mm, the focus position is the lower focus, and the assembly is slowly cooled in a vacuum state for 12 hours after electron beam welding, and the excess height of the electron beam weld 6 formed by electron beam welding is processed by mechanical processing to make the transition position between the U-shaped groove 3 and the I-shaped groove 2 smooth, so as to improve the fusion quality of laser wire welding and electron beam weld.

[0057] Therefore, compared with the traditional manual argon arc welding and metal arc gas shielded welding methods, the welding efficiency and weld quality are improved, and efficient welding of stainless steel thick plates is achieved.

[0058] Combined with Figure 4 , Figure 5 , Figure 6 , Figure 7 as well as Figure 8 Analysis of the effect of the welded product obtained by the composite welding method of this application. Figure 4 , in the cross-sectional view of the weld formed by electron beam welding, the weld is uniform and the fusion effect is good; refer to Figure 5 ,In the microscopic metallographic examination results, no microcracks were found in the weld; Figure 6 , in the tensile test results, the tensile strength of the weld is greater than that of the parent material; Figure 7 In the bending test results, the welded joint has no cracks when bent 180° sideways; Figure 8 , in the impact test results, the impact absorption energy is greater than 60J (Joule).

[0059] Therefore, the composite welding method in the embodiment of the present application can make the welding between the plates 1 stable, and the tensile strength of the welded joint (under room temperature conditions, such as: 23°C) is greater than that of the parent material, and the side bending test and impact test of the welded joint both meet the requirements of the specifications.

[0060] In summary, the composite welding method of austenitic stainless steel plates according to the embodiment of the present application has at least the following advantages compared with the prior art: (1) The hybrid welding method of electron beam welding combined with laser wire welding can achieve the welding of austenitic stainless steel sheets with a thickness of more than 160 mm; (2) Vacuum electron beam welding is used to weld the sheet metal at the I-type groove. There is no need for multi-layer and multi-pass welding, which can improve welding efficiency. Vacuum electron beam welding can avoid the impact of multiple heat inputs and improve the quality of weld joints. There is no need to fill the deposited metal, which saves welding materials and reduces welding costs. At the same time, vacuum electron beam welding has low line energy, fast welding speed, and small welding deformation.

[0061] (3) Laser wire welding is used to complete the welding of the assembly at the U-shaped groove, with small heat input and deformation and excellent weld quality.

[0062] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0063] In the description of this application, "first feature" or "second feature" may include one or more of the features.

[0064] In the description of the present application, “plurality” means two or more.

[0065] In the description of the present application, a first feature being “on” or “under” a second feature may include that the first and second features are directly in contact with each other, or may include that the first and second features are not in direct contact with each other but are in contact with each other via another feature therebetween.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0067] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A composite welding method for austenitic stainless steel plates, characterized in that: The following steps are involved: Step 1: preparing two sheets of sheet metal, and processing the ends of each sheet of sheet metal to form a U-shaped groove and an I-shaped groove; Step 2: Assembling the groove ends of the two sheets to form an assembly, and arranging the I-shaped grooves of the two sheets in a close fit; Step 3: placing the assembly in a working chamber, heating the assembly to a preset temperature, and evacuating the working chamber to a preset vacuum degree; Step 4: welding the assembly by electron beam welding; Step 5: Processing the electron beam welding weld excess height formed by electron beam welding to smoothly transition the transition position between the U-shaped groove and the I-shaped groove; Step 6: Perform filler wire welding on the U-shaped groove of the assembly.

2. The composite welding method of austenitic stainless steel plate according to claim 1, characterized in that: The step 2 also includes: A liner is fixedly arranged on one side of the assembly body away from the U-shaped groove, and an arc starting plate and an arc closing plate are respectively arranged on both ends of the I-shaped groove.

3. The composite welding method of austenitic stainless steel plate according to claim 2, characterized in that: Also includes step seven: The gasket fixed to the assembly is disassembled, and the surface of the laser filler wire welding seam of the filler wire welding is cleaned.

4. The composite welding method of austenitic stainless steel plate according to claim 1, characterized in that: In step 3, the preset temperature is above 100°C and the preset vacuum degree is lower than 5×10 -2 Pa.

5. The composite welding method of austenitic stainless steel plate according to claim 1, characterized in that: In the step 4, welding the assembly by electron beam welding comprises: Electron beam tack welding is performed on the I-shaped groove of the assembly with first preset parameters, and the focal position is the surface focal point; The assembly is electron beam welded along the electron beam welding seam of the electron beam tack welding with second preset parameters, and the focus position is the lower focus.

6. The composite welding method of austenitic stainless steel plate according to claim 5, characterized in that: The first preset parameters include: using a beam intensity of 5mA-15mA, a surface moving speed of 3mm / s, a voltage of 150kV, and a working distance of 600mm-1000mm; The second preset parameters include: a beam intensity of 180 mA-230 mA, a surface moving speed of 3 mm / s, a voltage of 150 kV, and a working distance of 600 mm-1000 mm.

7. The composite welding method of austenitic stainless steel plate according to claim 1, characterized in that: The step 4 further comprises, after the assembly is welded by electron beam welding: The assembly is cooled in the working chamber for a predetermined time.

8. The composite welding method of austenitic stainless steel plate according to claim 7, characterized in that: In the step 4, the preset time is not less than 12 hours.

9. The composite welding method of austenitic stainless steel plate according to claim 1, characterized in that: The filler wire welding process in step six is ​​one of a laser filler wire welding process and a submerged arc welding process.

10. The composite welding method of austenitic stainless steel plate according to claim 1, characterized in that: The sheet thickness is L and satisfies the relationship: L ≥ 80 mm; And / or, the thickness of each of the plates at the U-shaped groove is L1, and satisfies the relationship: L1 ≥ 30 mm; And / or, the thickness of each of the plates at the I-shaped groove is L2, and satisfies the relationship: L2≥50mm.

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