A method for improving super-low-temperature strength and toughness of a high manganese steel fusion welding joint based on in-situ formation of a high-entropy alloy in a weld

Abstract

The application belongs to the technical field of high manganese steel welding, and provides a method for improving the super-low-temperature strength and toughness of a high manganese steel fusion welding joint based on in-situ formation of a high-entropy alloy in a weld seam; a flux-cored wire is used to melt and weld the to-be-welded part of a low-temperature high manganese steel plate, thereby forming an FeCoCrNiMn high-entropy alloy structure in situ; in the flux-cored wire, the atomic percentage of each element is as follows: Fe 0.5-12%, Co 25-35%, Cr 25-35%, Ni 25-35%, and Mn 2-20%. The flux-cored wire is used to melt and weld the to-be-welded part of the low-temperature high manganese steel plate; the components of the flux-cored wire and the locally melted Fe and Mn elements of the low-temperature high manganese steel plate melt into the weld pool and undergo a metallurgical reaction, thereby forming an FeCoCrNiMn high-entropy alloy structure with equal atomic ratio or near equal atomic ratio in situ, and further improving the super-low-temperature strength and toughness of the low-temperature high manganese steel weld metal.

Description

Technical Field

[0001] This invention relates to the field of high manganese steel welding technology, and in particular to a method for improving the ultra-low temperature strength and toughness of high manganese steel welded joints based on the in-situ formation of a high-entropy alloy in the weld. Background Technology

[0002] With the continuous growth of global energy consumption and demand, clean energy and energy security are receiving increasing attention. Liquefied natural gas (LNG), with its high calorific value and low carbon content, is gradually gaining importance in the energy structure. The development of the LNG industry necessitates the construction of a large number of LNG storage (tanks) and receiving terminal facilities, leading to a demand for over 600,000 tons of steel for cryogenic applications.

[0003] Low-temperature austenitic high-manganese steel possesses excellent low-temperature toughness and strength, and has seen rapid development in recent years to replace 9Ni steel, a material used in LNG storage tanks with high nickel content, significantly reducing production costs. However, research has found that the cryogenic mechanical properties (especially low-temperature toughness) of high-manganese steel weld metal are significantly lower than those of the base metal, limiting the large-scale application of high-manganese steel in cryogenic engineering. Many researchers have explored ways to simultaneously improve the strength and cryogenic toughness of cryogenic high-manganese steel by changing the composition of filler materials and using different welding methods. The inventions described in "A High-Manganese Austenitic Welding Electrode for Welding Fe-Mn-Al System Low-Temperature Steel and Its Preparation Method (CN115625450A)," "A Submerged Arc Welding Wire, Flux, and Its Preparation and Welding Method for Low-Temperature High-Manganese Steel for LNG Ships (CN115647650A)," "A Consumable Electrode Solid Welding Wire for Welding Ultra-Low-Temperature Austenitic High-Manganese Steel (CN111805120A)," and "A Tungsten Inert Gas Welding Solid Welding Wire for Welding Ultra-Low-Temperature High-Manganese Steel (CN107009046B)" all improve the ultra-low-temperature performance of high-manganese steel weld metal by adding stabilizing austenitic elements such as Mn and Ni to make the weld metal microstructure fully austenitic. However, compared with the ultra-low-temperature performance of the low-temperature austenitic high-manganese steel base material, these methods do not significantly improve the low-temperature performance.

[0004] High-entropy alloys, formed from four or more main elements, promote the formation of disordered FCC or BCC solid solution structures through high mixing entropy. The high mixing entropy effect, lattice distortion effect, hysteresis diffusion effect, and cocktail effect endow the alloys with excellent mechanical properties. Currently, some scholars have attempted to use high-entropy alloys as filler materials, such as in "A TWIP Steel Laser Welding Method Based on a High-Entropy Alloy Interlayer (CN114734144A)," "A Steel-Aluminum Alloy Laser Welding Method Using a Nickel-Based High-Entropy Alloy Interlayer (CN114406469A)," and "High-Entropy Alloy Welding Wire for TIG Welding of Titanium / Stainless Steel and Its Application (CN104476010A)." However, these patents do not consider the influence of base metal melting on the weld metal composition during the welding process, leading to unsatisfactory high-entropy weld effects. Therefore, some scholars have proposed using multi-principal element high-entropy weld filler materials, considering the dilution effect of localized base metal melting, and modifying the initial chemical composition of the weld metal to directly form a high-entropy alloy structure within the weld. For example, the patents "A laser welding method for aluminum / steel based on an in-situ synthesized AlXCoCrFeNi high-entropy alloy intermediate layer (CN114951997A)," "A method for inhibiting the formation of brittle intermetallic compounds in weld seams by laser high-entropy filler powder welding (CN111590204A)," and "A eutectic high-entropy welding material and its preparation method and a method for welding titanium / steel composite plates (CN115846929A)" utilize the high-entropy effect and hysteresis diffusion effect of high-entropy alloys to inhibit the formation of brittle intermetallic compounds in dissimilar metal weld joints, but they cannot solve the problem that the ultra-low temperature performance of high-manganese steel weld metal is significantly lower than that of the base metal.

[0005] Therefore, it is necessary to provide a new filler material and its welding method to improve the ultra-low temperature strength and toughness of high-manganese steel. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art by providing a method for improving the ultra-low temperature strength and toughness of high-manganese steel welded joints based on the in-situ formation of high-entropy alloys in the weld.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for improving the ultra-low temperature strength and toughness of high-manganese steel fusion weld joints based on the in-situ formation of high-entropy alloys in the weld. The method uses flux-cored welding wire to perform fusion welding on the weldable parts of the low-temperature high-manganese steel plate, thereby forming an in-situ FeCoCrNiMn high-entropy alloy structure.

[0009] In flux-cored welding wire, the atomic percentages of each element are: Fe 0.5-12%, Co 25-35%, Cr 25-35%, Ni 25-35%, and Mn 2-20%.

[0010] As a preferred option, the welding area of ​​the low-temperature high-manganese steel plate is V-shaped bevel, with an opening angle of 45 to 90°.

[0011] As a preferred method, tungsten inert gas (TIG) welding is used for fusion welding.

[0012] Preferably, the thickness of the low-temperature high-manganese steel plate is 2-5mm, and the diameter of the flux-cored welding wire is 0.8-2.5mm.

[0013] Preferably, the current for tungsten inert gas welding is 24–75 A, the diameter of the tungsten needle is 1.6–2.4 mm, the inert gas is argon with a purity ≥99.99%, and the flow rate is 12–18 L / min.

[0014] Preferably, the preparation method of the flux-cored welding wire is as follows: using a Ni-Cr-Co nickel-based alloy strip as the outer sheath and a high-purity metal mixed powder as the flux core, the high-purity metal mixed powder is filled into the nickel-based alloy strip and drawn to obtain the flux-cored welding wire.

[0015] The atomic percentages of each element in the Ni-Cr-Co nickel-based alloy strip are: Co 26-32%, Cr 26-32%, and Ni 36-48%. The atomic percentages of each element in the mixture of the Ni-Cr-Co nickel-based alloy strip and high-purity metal mixed powder are: Fe 0.5-12%, Co 25-35%, Cr 25-35%, Ni 25-35%, and Mn 2-20%.

[0016] As a preferred option, the Ni-Cr-Co nickel-based alloy strip is in the form of a U-shaped groove. After being filled with high-purity metal mixed powder, the nickel-based alloy strip is closed from the U-shaped groove into an O-shape and then drawn to obtain a flux-cored welding wire.

[0017] Preferably, in the high-purity metal mixed powder, the purity of each metal powder is ≥99.99%, and the particle size of each metal powder is 100-300 mesh.

[0018] The beneficial effects of this invention include:

[0019] 1) Since the Fe and Mn elements brought into the weld pool by the melting of the low-temperature high-manganese steel base material during the welding process will change the metal composition of the weld, this invention uses a flux-cored wire composed of Fe, Co, Cr, Ni, and Mn as the main elements and the flux-cored wire as the filler material. The content of Fe, Co, Cr, Ni, and Mn in the flux-cored wire is controlled. The flux-cored wire is used to melt and weld the parts of the low-temperature high-manganese steel plate to be welded. The composition of the flux-cored wire and the Fe and Mn elements melted into the low-temperature high-manganese steel plate locally undergo a metallurgical reaction in the weld pool, forming an equiatomic or near-equiatomic FeCoCrNiMn high-entropy alloy structure in situ, thereby improving the ultra-low temperature strength and toughness of the low-temperature high-manganese steel weld metal.

[0020] 2) This invention utilizes the low stacking fault energy of FeCoCrNiMn high-entropy alloys with equiatomic or near-equiatomic ratios to increase the Shockley dislocation spacing during deformation, thereby hindering lateral slip and promoting the formation of nanotwins. Through the synergistic effect of multiple deformation mechanisms such as dislocation slip, stacking faults, deformed nanotwins, and HCP structural transformation, the comprehensive properties of high-manganese steel weld metal at ultra-low temperatures, including strength, ductility, and fracture toughness, are improved, thereby achieving the goal of improving the ultra-low temperature strength and toughness of high-manganese steel weld joints. Attached Figure Description

[0021] Figure 1 A macroscopic view of the low-temperature high-manganese steel welded joint obtained in Example 1;

[0022] Figure 2 This is a scanned element distribution diagram of the weld / base material interface of the low-temperature high-manganese steel welded joint obtained in Example 1;

[0023] Figure 3 The stress-strain curve of the low-temperature high-manganese steel welded joint obtained in Example 1 under tension at 77K.

[0024] Figure 4 The stress-strain curve of the low-temperature high-manganese steel welded joint obtained in Example 2 under tension at 77K.

[0025] Figure 5 This is a schematic diagram illustrating the principle of obtaining low-temperature high-manganese steel welds according to the present invention. Detailed Implementation

[0026] This invention provides a method for improving the ultra-low temperature strength and toughness of high-manganese steel fusion weld joints based on the in-situ formation of high-entropy alloys in the weld. The method uses flux-cored welding wire to perform fusion welding on the weldable parts of the low-temperature high-manganese steel plate, thereby forming an in-situ FeCoCrNiMn high-entropy alloy structure.

[0027] In flux-cored welding wire, the atomic percentages of each element are: Fe 0.5-12%, Co 25-35%, Cr 25-35%, Ni 25-35%, and Mn 2-20%.

[0028] In the flux-cored welding wire of the present invention, the content of Fe element is lower than the content of any one of Co, Cr and Ni element, the content of Mn element is lower than the content of any one of Co, Cr and Ni element, and the content of Mn element is not lower than the content of Fe element.

[0029] The flux-cored wire of the present invention contains 0.5 to 12% Fe by atomic percentage, preferably 2 to 7%, and more preferably 4 to 6%.

[0030] The flux-cored wire of the present invention contains 25-35% Co by atomic percentage, preferably 26-31%, and more preferably 28-30%.

[0031] The flux-cored welding wire of the present invention contains 25-35% Cr by atomic percentage, preferably 26-31%, and more preferably 28-30%.

[0032] The flux-cored wire of the present invention contains 25-35% Ni by atomic percentage, preferably 26-31%, and more preferably 28-30%.

[0033] The flux-cored wire of the present invention contains 2-20% Mn by atomic percentage, preferably 5-15%, and more preferably 8-10%.

[0034] The low-temperature high-manganese steel plate of the present invention is preferably Fe-23Mn-0.45C low-temperature high-manganese steel.

[0035] In this invention, the welding portion of the low-temperature high-manganese steel plate is preferably V-shaped, and the opening angle of the V-shaped bevel is preferably 45-90°, more preferably 50-80°, and even more preferably 60-70°.

[0036] In this invention, the preferred method of fusion welding is tungsten inert gas (TIG) welding.

[0037] In this invention, the thickness of the low-temperature high-manganese steel plate is preferably 2-5 mm, more preferably 3-4 mm, and even more preferably 3.5 mm; the diameter of the flux-cored welding wire is preferably 0.8-2.5 mm, more preferably 1.3-2 mm, and even more preferably 1.6-1.8 mm.

[0038] In this invention, the current for tungsten inert gas (TIG) welding is preferably 24–75 A, more preferably 45–65 A, and even more preferably 50–55 A; the diameter of the tungsten needle is preferably 1.6–2.4 mm, more preferably 1.8–2.2 mm, and even more preferably 2 mm; the inert gas is preferably argon, and the purity of the argon is preferably ≥99.99%, more preferably ≥99.995%; the flow rate is preferably 12–18 L / min, more preferably 14–16 L / min, and even more preferably 15 L / min.

[0039] In this invention, the flux-cored welding wire consists of an outer sheath and a flux core.

[0040] In this invention, the preferred method for preparing the flux-cored welding wire is as follows: using a Ni-Cr-Co nickel-based alloy strip as the outer sheath and a high-purity metal mixed powder as the flux core, the high-purity metal mixed powder is filled into the nickel-based alloy strip and drawn to obtain the flux-cored welding wire.

[0041] The atomic percentages of each element in the Ni-Cr-Co nickel-based alloy strip are: Co 26-32%, Cr 26-32%, and Ni 36-48%. The atomic percentages of each element in the mixture of the Ni-Cr-Co nickel-based alloy strip and high-purity metal mixed powder are: Fe 0.5-12%, Co 25-35%, Cr 25-35%, Ni 25-35%, and Mn 2-20%.

[0042] In the Ni-Cr-Co nickel-based alloy strip of the present invention, the atomic percentages of each element are preferably: Co 28-31%, Cr 28-31%, Ni 38-45%, and more preferably: Co 29-30%, Cr 29-30%, Ni 40-42%.

[0043] In this invention, the Ni-Cr-Co nickel-based alloy strip is in the form of a U-shaped groove. After being filled with high-purity metal mixed powder, the nickel-based alloy strip is closed from the U-shaped groove into an O-shape and then drawn to obtain a flux-cored welding wire.

[0044] In this invention, the Ni-Cr-Co nickel-based alloy strip is sequentially cleaned, dried, and then rolled into a U-shaped groove; the drying temperature is preferably 70-90°C, more preferably 75-85°C, and even more preferably 80°C.

[0045] In the high-purity metal mixed powder of the present invention, the purity of each metal powder is preferably ≥99.99%, and the particle size of each metal powder is preferably 100-300 mesh, more preferably 150-250 mesh, and even more preferably 200 mesh.

[0046] In this invention, the high-purity metal mixed powder is preferably obtained by heating each metal powder independently and then mixing them. The heating temperature is preferably 140-160°C, more preferably 145-155°C, and even more preferably 150°C. The heating time is preferably 1.5-2.5 hours, and even more preferably 2 hours.

[0047] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0048] In the embodiment, the low-temperature high-manganese steel plate is Fe-23Mn-0.45C low-temperature high-manganese steel.

[0049] Example 1

[0050] Using a Ni-Cr-Co nickel-based alloy strip as the outer sheath and a high-purity metal mixed powder as the core, the atomic percentages of each element in the Ni-Cr-Co nickel-based alloy strip are: Co 28%, Cr 28%, and Ni 44%. The atomic percentages of each element in the flux-cored welding wire are: Fe 6%, Co 28%, Cr 28%, Ni 28%, and Mn 10%. Subtracting the atomic percentages of each element in the outer sheath from the atomic percentages of each element in the flux-cored welding wire yields the Fe and Mn metal powder content.

[0051] Fe and Mn metal powders (both 99.99% pure, 200 mesh) were heated to 150°C in a vacuum furnace (0.08 Pa vacuum) and held for 2 hours. Then, they were stirred evenly in a powder mixer at 300 rpm to obtain a high-purity metal mixed powder. Ni-Cr-Co nickel-based alloy strips were cleaned with water, dried at 80°C, and rolled into 5mm×5mm×5mm U-shaped grooves. The high-purity metal mixed powder was filled into the nickel-based alloy strips, and the U-shaped grooves were closed into an O-shape using a flux-cored wire forming machine. The wire was then drawn step-by-step through a reducing mill (single-pass elongation coefficient of 1.25) to a diameter of 1.6mm to obtain the flux-cored wire.

[0052] A 60° V-groove was cut into the welding area of ​​a 3.5mm thick low-temperature high-manganese steel plate. The V-groove was then ground to obtain the low-temperature high-manganese steel plate to be welded. Tungsten inert gas (TIG) welding was performed on the high-manganese steel plate using a 1.6mm diameter flux-cored wire. The TIG welding current was 50A, the tungsten needle diameter was 2mm, and the argon gas purity was 99.99% with a flow rate of 15L / min. After welding, a near-equiatomic FeCoCrNiMn high-entropy alloy structure was formed in the weld zone of the high-manganese steel weld joint, resulting in the low-temperature high-manganese steel weld joint.

[0053] The macroscopic diagram of the low-temperature high-manganese steel welded joint obtained in this embodiment is as follows: Figure 1 As shown.

[0054] The elemental distribution of the weld (WZ) / base metal (BM) interface line of the low-temperature high-manganese steel welded joint obtained in this embodiment is as follows: Figure 2 As shown. From Figure 2 It can be seen that the weld interface has good bonding. The contents of the five elements Fe, Co, Cr, Ni and Mn in the weld are in the range of 20±10%, forming a weld with a high entropy alloy structure of FeCoCrNiMn with a near-equal atomic ratio.

[0055] The engineering stress-strain curve of the low-temperature high-manganese steel welded joint obtained in this embodiment under tensile stress at 77K is shown below. Figure 3 As shown. From Figure 3 It can be seen that the high-manganese steel welded joint has excellent low-temperature mechanical properties.

[0056] Example 2

[0057] Using a Ni-Cr-Co nickel-based alloy strip as the outer sheath and a high-purity metal mixed powder as the core, the atomic percentages of each element in the Ni-Cr-Co nickel-based alloy strip are: Co 30%, Cr 30%, and Ni 40%. The atomic percentages of each element in the flux-cored welding wire are: Fe 7%, Co 26%, Cr 26%, Ni 26%, and Mn 15%. Subtracting the atomic percentages of each element in the outer sheath from the atomic percentages of each element in the flux-cored welding wire yields the Fe and Mn metal powder content.

[0058] Fe and Mn metal powders (both 99.99% pure, 150 mesh) were heated to 145℃ in a vacuum furnace (0.09 Pa vacuum) and held for 2.5 h. Then, they were stirred evenly in a powder mixer at 300 r / min to obtain a high-purity metal mixed powder. Ni-Cr-Co nickel-based alloy strips were cleaned with water, dried at 75℃, and rolled into 5 mm × 5 mm × 5 mm U-shaped grooves. The high-purity metal mixed powder was filled into the nickel-based alloy strips, and the U-shaped grooves were closed into an O-shape using a flux-cored wire forming machine. The wire was then drawn step-by-step through a reducing mill (single-pass elongation coefficient of 1.23) to a diameter of 1.3 mm to obtain the flux-cored wire.

[0059] A 70° V-groove was cut into the welding area of ​​a 3.5mm thick low-temperature high-manganese steel plate. The V-groove was then ground to obtain the low-temperature high-manganese steel plate to be welded. Tungsten inert gas (TIG) welding was performed on the high-manganese steel plate using a 1.3mm diameter flux-cored wire. The TIG welding current was 55A, the tungsten needle diameter was 2mm, and the argon gas purity was 99.99% with a flow rate of 15L / min. After welding, a near-equiatomic FeCoCrNiMn high-entropy alloy structure was formed in the weld zone of the high-manganese steel weld joint, resulting in the low-temperature high-manganese steel weld joint.

[0060] The engineering stress-strain curve of the low-temperature high-manganese steel welded joint obtained in this embodiment under tensile stress at 77K is shown below. Figure 4 As shown. From Figure 4 It can be seen that the high manganese steel welded joint has excellent low-temperature performance.

[0061] Example 3

[0062] Using a Ni-Cr-Co nickel-based alloy strip as the outer sheath and a high-purity metal mixed powder as the core, the atomic percentages of each element in the Ni-Cr-Co nickel-based alloy strip are: Co 31%, Cr 31%, and Ni 38%. The atomic percentages of each element in the flux-cored welding wire are: Fe 2%, Co 30%, Cr 30%, Ni 30%, and Mn 8%. Subtracting the atomic percentages of each element in the outer sheath from the atomic percentages of each element in the flux-cored welding wire yields the Fe and Mn metal powder content.

[0063] Fe and Mn metal powders (both with a purity of 99.992% and a particle size of 250 mesh) were heated to 155°C in a vacuum furnace (vacuum degree of 0.08 Pa) and held at that temperature for 1.5 hours. Then, they were stirred evenly in a powder mixer at a speed of 300 r / min to obtain a high-purity metal mixed powder. Ni-Cr-Co nickel-based alloy strips were cleaned with water, dried at 85°C, and rolled into 5mm×5mm×5mm U-shaped grooves. The high-purity metal mixed powder was filled into the nickel-based alloy strips, and the U-shaped grooves were closed into an O-shape using a flux-cored wire forming machine. The wire was then drawn step-by-step through a reducing mill (single-pass elongation coefficient of 1.29) to a diameter of 1.8mm to obtain the flux-cored wire.

[0064] A 50° V-groove was cut into the welding area of ​​a 3mm thick low-temperature high-manganese steel plate. The V-groove was then ground to obtain the low-temperature high-manganese steel plate to be welded. Tungsten inert gas (TIG) welding was performed on the high-manganese steel plate using a 1.8mm diameter flux-cored wire. The TIG welding current was 45A, the tungsten needle diameter was 1.8mm, and the argon gas purity was 99.99% with a flow rate of 14L / min. After welding, a near-equiatomic FeCoCrNiMn high-entropy alloy structure was formed in the weld zone of the high-manganese steel weld joint, resulting in the low-temperature high-manganese steel weld joint.

[0065] Example 4

[0066] Using a Ni-Cr-Co nickel-based alloy strip as the outer sheath and a high-purity metal mixed powder as the core, the atomic percentages of each element in the Ni-Cr-Co nickel-based alloy strip are: Co 29%, Cr 29%, and Ni 42%. The atomic percentages of each element in the flux-cored welding wire are: Fe 2%, Co 31%, Cr 31%, Ni 31%, and Mn 5%. Subtracting the atomic percentages of each element in the outer sheath from the atomic percentages of each element in the flux-cored welding wire yields the metal powder content of Fe, Co, Cr, and Mn.

[0067] Fe, Co, Cr, and Mn metal powders (all with a purity of 99.995% and a particle size of 200 mesh) were heated to 150°C in a vacuum furnace (vacuum degree of 0.07 Pa) and held at that temperature for 2 hours. Then, they were stirred evenly in a powder mixer at a speed of 300 r / min to obtain a high-purity metal mixed powder. Ni-Cr-Co nickel-based alloy strips were cleaned with water and dried at 80°C, then rolled into 5mm × 5mm × 5mm U-shaped grooves. The high-purity metal mixed powder was filled into the nickel-based alloy strips, and the U-shaped grooves were closed into an O-shape using a flux-cored wire forming machine. The wire was then drawn step-by-step through a reducing mill (single-pass elongation coefficient of 1.32) to a wire diameter of 1.6mm to obtain the flux-cored wire.

[0068] A 45° V-groove was cut into the welding area of ​​a 4mm thick low-temperature high-manganese steel plate. The V-groove was then ground to obtain the low-temperature high-manganese steel plate to be welded. Tungsten inert gas (TIG) welding was performed on the high-manganese steel plate using a 1.6mm diameter flux-cored wire. The TIG welding current was 65A, the tungsten needle diameter was 2.2mm, and the argon gas purity was 99.99% with a flow rate of 16L / min. After welding, a near-equiatomic FeCoCrNiMn high-entropy alloy structure was formed in the weld zone of the high-manganese steel weld joint, resulting in the low-temperature high-manganese steel weld joint.

[0069] A schematic diagram illustrating the principle of obtaining low-temperature high-manganese steel welds in this invention is shown below. Figure 5 As shown.

[0070] This invention utilizes the main elements Fe and Mn that are locally melted into the weld pool by low-temperature high-manganese steel base material, and controls the composition and content of flux-cored welding wire composed of main elements such as Fe, Co, Cr, Ni, and Mn, so that the weld pool can form an in-situ high-entropy alloy structure with an equiatomic ratio or near-equiatomic ratio of FeCoCrNiMn with ultra-low temperature strength and toughness.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for improving the ultra-low temperature strength and toughness of high-manganese steel welded joints based on in-situ formation of high-entropy alloys in the weld, characterized in that, Flux-cored welding wire was used to perform fusion welding on the parts of the low-temperature high-manganese steel plate to be welded, forming an in-situ FeCoCrNiMn high-entropy alloy structure. In flux-cored welding wire, the atomic percentages of each element are: Fe 0.5–12%, Co 25–35%, Cr… 25~35%, Ni 25~35%, Mn 2~20%.

2. The method according to claim 1, characterized in that, The welding area of ​​the low-temperature high-manganese steel plate has a V-shaped bevel, and the opening angle of the V-shaped bevel is 45-90°.

3. The method according to claim 2, characterized in that, The fusion welding method is tungsten inert gas (TIG) shielded welding.

4. The method according to claim 3, characterized in that, The thickness of the low-temperature high-manganese steel plate is 2-5mm, and the diameter of the flux-cored welding wire is 0.8-2.5mm.

5. The method according to claim 4, characterized in that, The current for tungsten inert gas (TIG) welding is 24–75 A, the diameter of the tungsten needle is 1.6–2.4 mm, the inert gas is argon with a purity ≥99.99% and a flow rate of 12–18 L / min.

6. The method according to any one of claims 1 to 5, characterized in that, The preparation method of the flux-cored welding wire is as follows: using Ni-Cr-Co nickel-based alloy strip as the outer sheath and high-purity metal mixed powder as the flux core, the high-purity metal mixed powder is filled into the nickel-based alloy strip and drawn to obtain the flux-cored welding wire. The atomic percentages of each element in the Ni-Cr-Co nickel-based alloy strip are: Co 26-32%, Cr 26-32%, and Ni 36-48%. The atomic percentages of each element in the mixture of the Ni-Cr-Co nickel-based alloy strip and high-purity metal mixed powder are: Fe 0.5-12%, Co 25-35%, Cr 25-35%, Ni 25-35%, and Mn 2-20%.

7. The method according to claim 6, characterized in that, The Ni-Cr-Co nickel-based alloy strip is formed into a U-shaped groove. After being filled with high-purity metal mixed powder, the nickel-based alloy strip is closed from the U-shaped groove into an O-shape and then drawn to obtain a flux-cored welding wire.

8. The method according to claim 7, characterized in that, In high-purity metal mixed powder, the purity of each metal powder is ≥99.99%, and the particle size of each metal powder is 100-300 mesh.

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