Method for electron beam welding of high-entropy alloy and low-temperature steel based on tooth-shaped self-locking structure

Abstract

This invention proposes a method for electron beam welding of high-entropy alloys and low-temperature steel based on a toothed self-locking structure, belonging to the field of vacuum welding technology. It addresses the problem that welding cracks are easily generated during the welding process of high-entropy alloys and low-temperature steel. Existing methods that rely on adjusting welding parameters are only applicable to specific metal types and have complex processes with poor practicality. The method includes: Step 1: Determining the interface between the high-entropy alloy and low-temperature steel metal plates to be welded; Step 2: Workpiece assembly; Step 3: Vacuum welding; Step 4: Completing welding and heat preservation, then removing the welded workpiece. This invention uses a simple and easy-to-implement toothed self-locking joint, which can be directly integrated with existing welding processes. It mechanically increases the connection strength and stability. Compared with the traditional method of adding a metallurgical control intermediate layer, the self-locking structure ensures that the joint still has a certain connection strength after weld cracking, preventing immediate failure and providing processing time, thus serving as an early warning system.

Description

Technical Field

[0001] This invention relates to a method for electron beam welding of high-entropy alloys and low-temperature steel based on a toothed self-locking structure, belonging to the field of vacuum welding technology. Background Technology

[0002] Welding is a common method of joining metals in industry. With continuous technological and industrial development, the combination of different types of metals is becoming increasingly common in product design and manufacturing. This results in dissimilar metal welded joints, which facilitate the application and combination of various materials, expanding design and manufacturing freedom. The development of dissimilar metal welding is crucial for improving product quality, reducing costs, and enhancing industrial production efficiency. Simultaneously, dissimilar metal welding also offers possibilities for achieving sustainable development goals, such as its potential applications in lightweighting, energy conservation, and resource utilization; therefore, the prospects for dissimilar metal welding are very broad.

[0003] High-entropy alloys possess excellent comprehensive properties. Nanotwinning induced during deformation and work hardening result in superior mechanical properties at both room and low temperatures, exhibiting high resistance to hydrogen embrittlement and fracture toughness, making them promising candidates for cryogenic components. However, the complex manufacturing process and high cost of high-entropy alloys limit their application. Cryogenic steel, on the other hand, also possesses good resistance to cryogenic impact and is widely used in cryogenic pressure vessels, cryogenic pipelines, liquid ammonia fuel tanks, and other cryogenic components. Furthermore, its price is relatively low. Combining high-entropy alloys with cryogenic steel offers significant cost-effectiveness and facilitates the widespread application of high-entropy alloys.

[0004] However, high-entropy alloys and low-temperature steels exhibit differences in their thermophysical properties, such as a mismatch in their coefficients of linear expansion and specific heat capacity. When welding these two materials using electron beam welding, the different degrees of material expansion on both sides of the weld seam can easily lead to stress concentration in the weld area, causing welding cracks and reducing the performance and service reliability of the welded joint. Furthermore, electron beam welding involves extremely rapid cooling, while high-entropy alloys are highly sensitive to the welding cooling rate when welding dissimilar materials. Therefore, slow cooling is necessary during welding to prolong the high-temperature residence time of the weld seam, suppress welding stress, and reduce the tendency for welding cracks. This can generally be achieved by reducing the welding speed. Existing methods for improving the performance of dissimilar metal welded joints by controlling welding parameters, such as using off-beam welding, are only applicable to specific metal types. Additionally, methods for controlling weld metallurgical compatibility by adding a metal layer require significant material and time for process exploration, and are complex and impractical. This invention addresses the joint cracking problem by designing the joint shape as a toothed self-locking structure. Summary of the Invention

[0005] This invention addresses the problem that welding cracks easily occur during the welding of high-entropy alloys and low-temperature steel. Existing methods involving adjusting welding parameters are only applicable to specific metal types and have complex processes, resulting in poor practicality. Therefore, this invention proposes a method for electron beam welding of high-entropy alloys and low-temperature steel based on a toothed self-locking structure, specifically including:

[0006] Step 1: Prepare high-entropy alloy and low-temperature steel metal plates of the same size, and process the interface to be welded on the high-entropy alloy and low-temperature steel metal plates;

[0007] Step 2: Perform ultrasonic cleaning on the processed high-entropy alloy and low-temperature steel metal plates, polish the interface to be welded with sandpaper, wipe the interface to be welded with petroleum ether after polishing, and blow dry immediately after wiping.

[0008] Step 3: Connect the high-entropy alloy and low-temperature steel metal plates along the toothed path, snap them together along the thickness direction, place the assembled high-entropy alloy and low-temperature steel metal plates on the welding fixture and fix them, and place the welding fixture in the vacuum chamber of the electron beam welding machine.

[0009] Step 4: Turn on the vacuum system. When the vacuum level in the vacuum chamber reaches the preset value, start the electron gun and motion system, select the corresponding welding parameters, and control the electron beam to weld the high-entropy alloy and low-temperature steel along the toothed mating surface. After welding, keep it warm.

[0010] Step 5: After heat preservation, remove the workpiece to complete the welding of high-entropy alloy and low-temperature steel.

[0011] Optionally, in step 1, the interface to be welded is toothed, and the height and width of the teeth are greater than the width of the weld.

[0012] Optionally, in step 2, the ultrasonic frequency is 20kHz, the ultrasonic cleaning time is 5 minutes, and the sandpaper mesh is 1000-2000.

[0013] Optionally, in step 3, the docking interface is a toothed self-locking structure with a rounded corner radius of 2.5mm, a bevel angle of 80°, and a tooth width of 8mm.

[0014] Optionally, the preset vacuum level in the vacuum chamber in step 4 is 5×10⁻⁶. -2 Pa, holding time is 10-20 min, acceleration voltage of electron gun and motion system is 60 kV, welding beam current is 20 mA, welding speed is 10 mm / s.

[0015] The beneficial effects of this invention are:

[0016] (1) This invention is suitable for welding high-entropy alloys and low-temperature steel with a thickness of 2-5mm. By controlling the welding energy distribution through electron beam welding, the toothed weld can be accurately tracked to achieve precise welding and obtain an electron beam welded joint with a self-locking structure.

[0017] (2) The present invention uses a simple and easy-to-use toothed self-locking joint, which can be directly combined with the existing welding process. It increases the connection strength and stability through mechanical means. Compared with the traditional method of adding a metallurgical control intermediate layer, the self-locking structure ensures that the joint still has a certain connection strength after the weld cracks and will not fail immediately. It reserves time for processing and has an early warning function.

[0018] (3) Compared with traditional straight welds, the direction of toothed welds changes continuously, which changes the stress distribution of the joint and suppresses stress concentration after welding. When local cracks occur in the weld, straight welds are prone to cracking along the weld, while the direction of toothed welds has a large angle deflection, which can effectively suppress cracks from spreading along a straight line.

[0019] (4) Under the same workpiece size and welding speed, the welding time of the toothed weld is longer, the high temperature dwell time of the weld is longer, and the cooling rate is slower, which is beneficial to suppress the generation of welding cracks. Attached Figure Description

[0020] Figure 1 A flowchart of the method for electron beam welding of high-entropy alloys and low-temperature steel based on a toothed self-locking structure provided by the present invention;

[0021] Figure 2 This is an assembly diagram illustrating the welding process between high-entropy alloys and low-temperature steel provided by the present invention.

[0022] Figure 3 A detailed dimension drawing of the weld seam of a high-entropy alloy and low-temperature steel metal plate with dimensions of 200mm×50mm×2mm provided for this invention;

[0023] Figure 4 A detailed dimension drawing of the weld seam of a high-entropy alloy and low-temperature steel metal plate with dimensions of 260mm×50mm×3mm provided for this invention;

[0024] Figure 5 The present invention provides a detailed dimension drawing of the weld seam of a high-entropy alloy and low-temperature steel metal plate with dimensions of 280mm×60mm×4mm. Detailed Implementation

[0025] Specific implementation method one: Combining Figure 1-3 This implementation method is described as follows: Figure 1 As shown, the steps of the method for electron beam welding of high-entropy alloys and low-temperature steel based on a toothed self-locking structure described in this embodiment include:

[0026] S1: Determine the welding interface between the high-entropy alloy and the low-temperature steel metal plate;

[0027] This embodiment prepares two pieces of high-entropy alloy and low-temperature steel materials with dimensions of 200mm × 50mm × 2mm, such as... Figure 3 As shown, teeth with a width of 6mm, a spacing of 6mm, and a 2mm rounded corner are machined on the interface to be welded, so that the mating surfaces of the two plates match each other and are smooth and flat. The tooth spacing and tooth width can be adjusted accordingly for plates of different sizes.

[0028] Compared with traditional straight welds, the toothed weld in this embodiment has a continuously changing direction, which changes the stress distribution of the joint and suppresses stress concentration after welding. When local cracks occur in the weld, straight welds are prone to cracking along the weld, while the toothed weld has a large angle of deflection, which can effectively suppress the crack from propagating in a straight line.

[0029] S2: Workpiece assembly;

[0030] S201: The processed high-entropy alloy and low-temperature steel metal plates are ultrasonically cleaned at a frequency of 20kHz for 5 minutes to remove oil, sewage stains and other contaminants.

[0031] S202: Use 1000-2000# sandpaper to polish the interface to be welded to remove contaminants such as oxides and rust, then wipe the interface to be welded with petroleum ether and blow dry immediately after wiping;

[0032] S203: As Figure 2 As shown, the metal plates are matched along the toothed path and interlocked together along the thickness direction to ensure that the interfaces to be welded on the metal plates are aligned and overlapped.

[0033] S3: Vacuum welding;

[0034] S301: Place the assembled high-entropy alloy and low-temperature steel metal plates on the welding fixture and fix them. After fixing, place the fixture and metal plates in the vacuum chamber of the electron beam welding machine and turn on the vacuum system.

[0035] This embodiment uses a simple and easy-to-implement toothed self-locking joint, which can be directly combined with existing welding processes. It increases the connection strength and stability through mechanical means. Compared with the traditional method of adding a metallurgical control intermediate layer, the self-locking structure ensures that the joint still has a certain connection strength after the weld cracks, and will not fail immediately. It provides processing time and has an early warning function.

[0036] S302: The vacuum level of the vacuum chamber reaches 5×10⁻⁶. -2 At time Pa, the electron gun and motion system are activated, with the focus position on the upper surface of the metal plate. Appropriate welding parameters are selected to control the electron beam to weld high-entropy alloys and low-temperature steel along the toothed weld seam.

[0037] S4: Complete welding and maintain temperature, then remove the welded workpiece;

[0038] After welding, the workpiece is kept in a vacuum chamber for 10 to 20 minutes before being removed.

[0039] Specific Implementation Method Two: Combining Figure 1 , Figure 2 and Figure 4 This implementation method is described as follows: Figure 1 As shown, the steps of the method for electron beam welding of high-entropy alloys and low-temperature steel based on a toothed self-locking structure described in this embodiment include:

[0040] S1: Determine the welding interface between the high-entropy alloy and the low-temperature steel metal plate;

[0041] This embodiment prepares two pieces of high-entropy alloy and low-temperature steel materials with dimensions of 260mm × 50mm × 3mm, such as... Figure 4 As shown, a tooth-shaped mating surface is machined on the long side, with a fillet radius of 2.5mm, a bevel angle of 80°, and a tooth width of 8mm.

[0042] S2: Workpiece assembly;

[0043] S201: The processed high-entropy alloy and low-temperature steel metal plates are ultrasonically cleaned at a frequency of 20kHz for 5 minutes to remove oil, sewage stains and other contaminants.

[0044] S202: Use 1000-2000# sandpaper to polish the interface to be welded to remove contaminants such as oxides and rust, then wipe the interface to be welded with petroleum ether and blow dry immediately after wiping;

[0045] S203: As Figure 2 As shown, the metal plates are matched along the toothed path and interlocked together along the thickness direction to ensure that the interfaces to be welded on the metal plates are aligned and overlapped.

[0046] S3: Vacuum welding;

[0047] S301: Place the assembled high-entropy alloy and low-temperature steel metal plates on the welding fixture and fix them. After fixing, place the fixture and metal plates in the vacuum chamber of the electron beam welding machine and turn on the vacuum system.

[0048] S302: The vacuum level of the vacuum chamber reaches 5×10⁻⁶. -2 At Pa, the electron gun and motion system are activated, the accelerating voltage is 60kV, the focusing position is the upper surface of the metal plate, the welding beam current is 20mA, and the electron beam is controlled to weld high-entropy alloys and low-temperature steel along the toothed mating surface at a welding speed of 10mm / s.

[0049] S4: Complete welding and maintain temperature, then remove the welded workpiece;

[0050] After welding, the workpiece is kept in a vacuum chamber for 10 to 20 minutes before being removed.

[0051] Specific implementation method three: Combining Figure 1 , Figure 2 and Figure 5 This implementation method is described as follows: Figure 1 As shown, the steps of the method for electron beam welding of high-entropy alloys and low-temperature steel based on a toothed self-locking structure described in this embodiment include:

[0052] S1: Determine the welding interface between the high-entropy alloy and the low-temperature steel metal plate;

[0053] This embodiment prepares two pieces of high-entropy alloy and low-temperature steel materials with dimensions of 280mm × 60mm × 4mm, such as... Figure 5 As shown, the tooth-shaped interface is machined on the long side, with a fillet radius of 3mm, a bevel angle of 80°, and a tooth width of 10mm.

[0054] S2: Workpiece assembly;

[0055] S201: The processed high-entropy alloy and low-temperature steel metal plates are ultrasonically cleaned at a frequency of 20kHz for 5 minutes to remove oil, sewage stains and other contaminants.

[0056] S202: Use 1000-2000# sandpaper to polish the interface to be welded to remove contaminants such as oxides and rust, then wipe the interface to be welded with petroleum ether and blow dry immediately after wiping;

[0057] S203: As Figure 2 As shown, the metal plates are matched along the toothed path and interlocked together along the thickness direction to ensure that the interfaces to be welded on the metal plates are aligned and overlapped.

[0058] S3: Vacuum welding;

[0059] S301: Place the assembled high-entropy alloy and low-temperature steel metal plates on the welding fixture and fix them. After fixing, place the fixture and metal plates in the vacuum chamber of the electron beam welding machine and turn on the vacuum system.

[0060] S302: The vacuum level of the vacuum chamber reaches 5×10⁻⁶. -2 At Pa, the electron gun and motion system are activated, the accelerating voltage is 60kV, the focusing position is the upper surface of the metal plate, the welding beam current is 20mA, and the electron beam is controlled to weld high-entropy alloys and low-temperature steel along the toothed interface at a welding speed of 10mm / s.

[0061] S4: Complete welding and maintain temperature, then remove the welded workpiece;

[0062] After welding, the workpiece is kept in a vacuum chamber for 10 to 20 minutes before being removed.

[0063] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A method for electron beam welding of high-entropy alloys and cryogenic steels based on a tooth-shaped self-locking structure, characterized in that, The steps of the method for electron beam welding high-entropy alloys and low-temperature steel based on a toothed self-locking structure include: Step 1: Prepare high-entropy alloy and low-temperature steel metal plates of the same size, and process the interface to be welded on the high-entropy alloy and low-temperature steel metal plates; In step 1, the interface to be welded is toothed, and the height and width of the teeth are greater than the width of the weld. Step 2: Perform ultrasonic cleaning on the processed high-entropy alloy and low-temperature steel metal plates, polish the interface to be welded with sandpaper, wipe the interface to be welded with petroleum ether after polishing, and blow dry immediately after wiping. Step 3: Connect the high-entropy alloy and low-temperature steel metal plates along the toothed path, snap them together along the thickness direction, place the assembled high-entropy alloy and low-temperature steel metal plates on the welding fixture and fix them, and place the welding fixture in the vacuum chamber of the electron beam welding machine. In step 3, the docking interface is a toothed self-locking structure with a rounded corner radius of 2.5mm, a bevel angle of 80°, and a tooth width of 8mm. Step 4: Turn on the vacuum system. When the vacuum level in the vacuum chamber reaches the preset value, start the electron gun and motion system, select the corresponding welding parameters, and control the electron beam to weld the high-entropy alloy and low-temperature steel along the toothed mating surface. After welding, keep it warm. The preset vacuum level in the vacuum chamber in step 4 is [value missing]. The heat preservation time is 10-20 min, the acceleration voltage of the electron gun and motion system is 60 kV, the welding beam current is 20 mA, and the welding speed is 10 mm / s. Step 5: After heat preservation, remove the workpiece to complete the welding of high-entropy alloy and low-temperature steel.

2. The method for electron beam welding of high-entropy alloys and low-temperature steel based on a toothed self-locking structure according to claim 1, characterized in that, In step 2, the ultrasonic frequency is 20 kHz, the ultrasonic cleaning time is 5 minutes, and the sandpaper mesh is 1000~2000.

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