Al-based high-entropy alloy welding wire for surfacing of TP347H pipe as well as preparation method and application of Al-based high-entropy alloy welding wire

Abstract

The invention discloses an Al-based high-entropy alloy welding wire for surfacing of a TP347H pipe and a preparation method and application of the Al-based high-entropy alloy welding wire, and particularly relates to the field of metal materials, the Al-based high-entropy alloy welding wire for surfacing of the TP347H pipe comprises a flux core and a welding skin, and powder of the flux core comprises, by mass, 38.0%-40.0% of Al powder, 16.0%-20.0% of Cr powder, 8.0%-10.0% of Ni powder, 16.0%-18.0% of Cu powder, 3.0%-6.0% of Ti powder and the balance Fe powder; the sum of the mass percentages of the components is 100%. According to the welding wire, an Al-based high-entropy alloy system is designed, the stability at the high temperature is high, the abrasion resistance of high-temperature abrasive particles is high, the problems of surface abrasion and corrosion in the service process of a TP347H pipe can be solved, and the service life of the pipe is effectively prolonged.

Description

Technical Field

[0001] This invention belongs to the field of metallic materials, specifically relating to an Al-based high-entropy alloy welding wire for TP347H pipe overlay welding, its preparation method, and its application. Background Technology

[0002] TP347H austenitic stainless steel, due to its excellent high-temperature strength and structural stability, is widely used in key pipe fittings of superheaters and reheaters in ultra-supercritical thermal power plant boilers. These fittings operate for extended periods in extreme environments characterized by high temperatures, high pressures, and the presence of corrosive media and hard fly ash. Their pipe walls inevitably suffer from severe high-temperature oxidation, high-temperature corrosion, and erosion wear from flue gas particles. The coupled effect of these multiple failure modes leads to continuous thinning of the pipe wall, posing significant safety hazards and potentially causing serious accidents such as pipe rupture, severely threatening the safe operation and economic benefits of power plants.

[0003] To address the aforementioned issues, preparing a high-performance, wear- and corrosion-resistant weld overlay layer on the surface of critical pipeline components is an effective strategy for extending service life and providing protection. However, existing conventional weld overlay materials on the market (such as cobalt-based and nickel-based alloys) are insufficient to meet the requirements of this complex operating condition. These materials generally face a key performance contradiction: materials with good weldability often lack sufficient high-temperature erosion resistance; while materials with excellent high-temperature erosion resistance often suffer from poor weldability and cracking of the cladding layer due to complex alloy systems or the presence of a large number of hard and brittle phases. This contradiction severely restricts the effectiveness and reliability of surface protection technology. The root cause lies in the difficulty of achieving a synergistic improvement in high strength, high hardness, good ductility, toughness, and weldability using traditional alloy design concepts.

[0004] Therefore, developing a novel surfacing material that combines excellent weldability with superior high-temperature erosion resistance has become a pressing technical challenge in this field. High-entropy alloys, as a novel material that breaks away from traditional principal component design concepts, offer a new direction for solving this problem. Through the ingenious combination of multiple principal components, high-entropy alloys are expected to form a stable solid solution matrix in the microstructure and generate nanoscale reinforcing phases in situ, thereby achieving a good balance between strength and toughness and avoiding the high weld crack sensitivity caused by coarse and brittle phases in traditional materials.

[0005] Chinese patent application CN108161277A discloses a welding wire for the transition layer of TA1-Cu-Q345 steel, comprising a flux core and a weld coat. The flux powder is composed of the following components by mass percentage: Ni powder 40-60%, Al powder 20-30%, Si powder 10-20%, and Mn powder 5-10%, with the sum of the mass percentages of these components being 100%. This welding wire solves the problem of insufficient weld strength on the steel side when directly fusion welding TA1-Cu-Q345 three-layer composite plates. However, the patent does not mention improvements for high-temperature oxidation, high-temperature corrosion, and erosion wear from particulate matter in TP347H austenitic stainless steel, therefore further exploration and improvement are needed. Summary of the Invention

[0006] The technical problem to be solved by this invention is how to develop a new Al-based high-entropy alloy welding material suitable for arc welding process. Through innovative composition and microstructure design, the bottleneck problem of performance mismatch of existing welding materials is fundamentally solved. An Al-Cr-Cu-Fe-Ni-Ti alloy system is designed to solve the surface wear and corrosion problems of TP347H pipe during service.

[0007] The present invention solves the above-mentioned technical problems through the following technical means: The first aspect of this invention provides an Al-based high-entropy alloy welding wire for TP347H pipe overlay welding, comprising a flux core and a welding sheath, wherein the flux core is composed of the following components by mass percentage: 38.0~40.0% Al powder, 16.0~20.0% Cr powder, 8.0~10.0% Ni powder, 16.0~18.0% Cu powder, 3.0~6.0% Ti powder, and the remainder being Fe powder, the sum of the mass percentages of the above components being 100%; the filling rate of the flux core in the welding wire is controlled at 18~20%.

[0008] Preferably, the filling rate = powder mass / (steel strip volume + powder mass) × 100%.

[0009] Preferably, the purity of Al powder is ≥99.9%, the purity of Cr powder is ≥99.9%, the purity of Ni powder is ≥99.9%, the purity of Cu powder is ≥99.9%, the purity of Ti powder is ≥99.9%, and the purity of Fe powder is ≥99.9%, and the particle size of all six powders is 100~200 mesh.

[0010] Preferably, the material of the weld bead is stainless steel; more preferably, it is 304 steel strip.

[0011] Preferably, the weld skin is made of 304 steel strip, the thickness of which is 0.2~0.6mm and the width is 5~9mm, and more preferably the thickness is 0.4mm and the width is 7mm.

[0012] A second aspect of the present invention provides a method for preparing the Al-based high-entropy alloy welding wire for TP347H pipe overlay welding, comprising the following steps: (1) Weigh out Al powder 38.0~40.0%, Cr powder 16.0~20.0%, Ni powder 8.0~10.0%, Cu powder 16.0~18.0%, Ti powder 3.0~6.0%, and the remainder is Fe powder, according to the mass percentages of the above powder components. The sum of the mass percentages of the above powder components is 100%. (2) Place the powder weighed in step 1 into a vacuum heating furnace and heat it to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing. (3) Use alcohol to remove the grease from the surface of the 304 steel strip, and wrap the powder obtained in step 2 inside the 304 steel strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm. (4) After the first drawing process is completed, the die hole diameter is reduced in sequence to finally obtain flux-cored welding wire with a diameter of 1.0~1.2mm; (5) After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0013] Preferably, in step (1), the purity of Al powder is ≥99.9%, the purity of Cr powder is ≥99.9%, the purity of Ni powder is ≥99.9%, the purity of Cu powder is ≥99.9%, the purity of Ti powder is ≥99.9%, the purity of Fe powder is ≥99.9%, and the particle size of the six powders is 100~200 mesh.

[0014] Preferably, in step (2), the heating method is to keep warm at 180~220℃ for 1~3 hours.

[0015] Preferably, in step (2), the mixing time is 1 to 3 hours.

[0016] Preferably, in step (3), the filling rate of the flux core in the welding wire is controlled at 18~20%.

[0017] Preferably, in step (3), the thickness of the 304 steel strip is 0.4 mm and the width is 7 mm.

[0018] Preferably, in step (4), the mold hole diameter decreases sequentially from 2.4mm, 2.2mm, 2.1mm, 1.9mm, 1.8mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm, 1.2mm, 1.1mm, to 1.0mm.

[0019] A third aspect of the present invention proposes the application of the above-mentioned Al-based high-entropy alloy welding wire in the surfacing welding of TP347H pipe.

[0020] A fourth aspect of the present invention provides a welding method for the above-mentioned Al-based high-entropy alloy welding wire, comprising the following steps: Arc welding was performed on the surface of TP347H pipe using the aforementioned Al-based high-entropy alloy welding wire. The welding current was 180~220A, the welding voltage was 13~16V, and the shielding gas was 80%Ar+20%He. Two layers were welded. The thickness of the first layer was controlled at 1.8~2.0mm, the weld overlap rate was 20~30%, and the interpass temperature was controlled below 150℃. The thickness of the second layer was controlled at 1.9~2.2mm, the weld overlap rate was 10~20%, and the interpass temperature was controlled below 100℃.

[0021] The beneficial effects of this invention are as follows: (1) The welding wire of this invention is designed with Al-Cr-Cu-Fe-Ni-Ti alloy system, which has high stability at high temperature and strong resistance to wear of high temperature abrasive particles, thus perfectly solving the surface wear and corrosion problems of TP347H pipe during service and improving the service life of the pipe.

[0022] (2) This invention patent designs a cladding metal microstructure composition mode of face-centered cubic (FCC) + body-centered cubic (BCC) + a small amount of hard phase through reasonable element ratio and microstructure design, thereby ensuring high bonding strength between the weld overlay and the pipe substrate while ensuring excellent high temperature erosion resistance.

[0023] (3) The welding wire of the present invention improves the high temperature resistance of the weld overlay layer by means of Al, Cr and Ti elements; improves the toughness of the weld overlay layer by means of Ni and Cu; and improves the wear resistance of the weld overlay metal by means of Fe-Ti hard phase and Laves phase.

[0024] (4) The welding wire provided by the present invention can be used for welding with either TIG or MIG, and is easy to implement and apply in engineering sites. The welding wire preparation process of the present invention is simple, and the flux powder is wrapped in the welding skin and then drawn. The preparation cycle is short and the production efficiency is high.

[0025] (5) The main alloy components of the welding wire designed in this invention have the following functions and roles: 1. The main alloying element in the cladding metal of the welding wire is Fe: The main alloying element of the TP347H pipe is Fe, and the main alloying element of the designed welding wire is also Fe, ensuring excellent metallurgical bonding performance between the weld layer and the pipe. In addition, Fe is inexpensive, which can further reduce the cost of the welding wire and increase its application value.

[0026] 2. The main alloying element in the weld metal cladding is Cr: Cr is introduced into the weld metal through the weld skin and flux powder. Cr is the main alloying element in the formation of Fe-Cr solid solution (BCC phase) and Fe-Cr-Ni solid solution (FCC phase) in high-entropy alloy welds. Cr is an indispensable key element in high-temperature alloy systems, and its core role is to endow the alloy with the ability to serve in extreme high-temperature environments. In terms of resistance to high-temperature oxidation, the core value of Cr lies in its selective oxidation, dynamically forming a dense, continuous Cr2O3 protective film on the alloy surface with extremely strong adhesion to the matrix. This oxide film has an extremely low oxygen ion diffusion coefficient and excellent stability at high temperatures, effectively blocking the inward erosion of corrosive media such as oxygen and sulfur, becoming the first barrier against high-temperature oxidation and hot corrosion. For components that serve for a long time in high-temperature flue gas, this self-generated, repairable protective film is a decisive factor in ensuring its service life. At the same time, Cr atoms, through solid solution in the matrix, induce significant lattice distortion, producing a strong solid solution strengthening effect, thereby improving the alloy's strength and hardness at both room temperature and high temperature. This not only enhances the deformation resistance of the alloy matrix but also provides solid support for its resistance to wear failure at high temperatures. Therefore, in the design of high-temperature alloys, the Cr content is directly related to the material's high-temperature environmental durability and structural stability, and is a key factor in balancing the alloy's oxidation resistance, corrosion resistance, and mechanical properties.

[0027] 3. The welding wire cladding metal contains a certain amount of Al: Al is a powerful body-centered cubic (BCC) structure-forming element. In this multi-principal-element system, the addition of Al significantly promotes the formation and stabilization of the BCC solid solution phase. The BCC phase typically possesses high strength and hardness, while the face-centered cubic phase provides better plasticity. Therefore, by precisely controlling the Al content, the ratio of FCC to BCC phases in the alloy can be effectively regulated, thereby achieving an optimized balance between alloy strength and toughness. This is crucial for weld overlays that require both wear resistance and crack prevention. At high temperatures, Al has a strong affinity for oxygen, preferentially forming a dense, stable, and well-adhesive Al2O3 (alumina) protective film on the alloy surface. This film grows slowly but provides extremely strong protection, far more stable than the FeO film on ordinary steel surfaces. It effectively prevents the inward diffusion of oxygen atoms and the outward diffusion of metal atoms, thus greatly enhancing the alloy's resistance to high-temperature oxidation and hot corrosion in high-temperature flue gas environments.

[0028] 4. The welding wire cladding metal contains a certain amount of Ni: Ni plays a core role as a "phase structure stabilizer" and "toughness coordinator" in this hexa-element high-entropy alloy. Its role is mainly reflected in the following aspects: 1) Promoting the formation and stabilization of the FCC phase and optimizing toughness and plasticity. Ni is a strong face-centered cubic structure stabilizing element. In this system, Al and Cr are strong BCC phase forming elements, which tend to make the alloy harder and more brittle. The addition of Ni can effectively counteract this tendency and promote the formation of the FCC phase with better toughness or the formation of an FCC / BCC dual-phase structure. This dual-phase structure is the key to achieving a combination of high strength and good plasticity in high-entropy alloys. By ensuring that the alloy has sufficient toughness and ductility, Ni directly determines the resistance to thermal fatigue and the ability to resist cracking during welding. 2) Enhancing the thermal stability of the alloy. The "hysteresis diffusion" effect of high-entropy alloys means that atoms migrate more slowly in the crystal lattice. The addition of Ni further enhances this effect, helping to suppress the excessive growth and coarsening of brittle intermetallic compounds (such as σ phase and Laves phase) during high-temperature welding or long-term high-temperature service. This keeps the alloy microstructure stable at high temperatures, which is crucial for maintaining the performance of the weld overlay under long-term high-temperature conditions. 3) Balancing the segregation tendency of Cu. The mixing enthalpy of Cu with elements such as Fe and Cr in the system is positive, making it prone to segregation during solidification. Ni and Cu are miscible, and the addition of Ni helps to alleviate the microsegregation tendency of Cu, making the microstructure more uniform and thus improving the overall performance of the alloy.

[0029] 5. The welding wire cladding metal contains a certain amount of Ti: Ti is a strong carbide and nitride forming element. Even if the alloy contains only trace amounts of C or N, Ti can preferentially combine with them to form high-hardness, high-thermal-stability nanoscale hard particles such as TiC or TiN. More importantly, Ti can react with major elements such as Fe and Ni to promote the dispersed precipitation of Ti-rich Laves phase or other intermetallic compounds. These fine second-phase particles can effectively pin grain boundaries and hinder dislocation movement, producing a significant precipitation strengthening effect, thereby greatly improving the strength, hardness, and high-temperature wear resistance of the alloy. At the same time, the addition of Ti also helps to refine the solidification structure and optimize the overall mechanical properties of the alloy.

[0030] 6. The welding wire cladding metal contains a certain amount of Cu: Cu plays a unique and crucial "performance regulator" role in Al-Cr-Cu-Fe-Ni-Ti high-entropy alloys. Due to its positive enthalpy of mixing with main elements such as Fe and Cr, Cu tends to agglomerate during solidification, forming nanoscale Cu-rich phases. These soft second phases, distributed within the hard BCC / FCC matrix, act as a solid lubricant during friction, effectively reducing the friction coefficient and significantly improving the alloy's resistance to adhesive wear. However, this characteristic is a double-edged sword; if the Cu content is not properly controlled, its agglomeration intensifies, leading to uneven microstructure and decreased continuity, thus weakening the overall strength. Therefore, precisely controlling the Cu content is key to realizing its beneficial effects, avoiding its negative impacts, and ultimately optimizing the alloy's strength-toughness balance and wear resistance.

[0031] Of course, implementing any product or method of the present invention does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0032] Figure 1 The image shows the metallographic structure of the weld overlay obtained by using the Al-based high-entropy alloy welding wire prepared in Example 1 to weld over the surface of a TP347H pipe.

[0033] Figure 2 The image shows the cross-sectional morphology of the weld overlay layer after a 12-hour high-temperature corrosion test at 700°C, obtained by overlaying the Al-based high-entropy alloy welding wire prepared in Example 1 onto the surface of a TP347H pipe.

[0034] Figure 3 The image shows the surface morphology of the weld overlay layer obtained after a high-temperature erosion test at 600°C (10 min) on the surface of a TP347H pipe using the Al-based high-entropy alloy welding wire prepared in Example 1. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical terms used below have the same meaning as understood by those skilled in the art.

[0036] Unless otherwise specified, the test materials and reagents used in the following examples are commercially available or prepared by known methods.

[0037] Unless otherwise specified, all techniques or conditions described in the embodiments can be performed in accordance with the techniques or conditions described in the literature in this field or in the product manual. Unless otherwise specified, the quantitative experiments in the following embodiments are all repeated three times or more, and the results are averaged.

[0038] Example 1 A method for preparing Al-based high-entropy alloy welding wire for TP347H pipe overlay welding: Step 1: Weigh out the following components by mass percentage: Al 39.47%, Cr 17.26%, Ni 9.13%, Cu 17.82%, Ti 4.95%, with the remainder being Fe. The sum of the mass percentages of the above components is 100%. Step 2: Place the powder weighed in Step 1 into a vacuum heating furnace and heat it at 180℃ for 1 hour to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1 hour. Step 3: Remove the grease from the surface of the 304 steel strip with alcohol, and wrap the flux-cored wire powder prepared in Step 2 inside the 304 steel strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm, and the filling rate of the flux-cored wire powder is controlled at 19.86%. Step 4: After the first drawing process is completed, the die hole diameter is reduced in sequence to finally obtain flux-cored welding wire with a diameter of 1.0~1.2mm; Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0039] A welding method using an Al-based high-entropy alloy welding wire prepared in Example 1 for surfacing TP347H pipe: Arc welding is performed on the surface of the TP347H pipe using the welding wire of this invention. The welding current is 180A, the welding voltage is 13V, and the shielding gas is 80%Ar + 20%He. Two layers are surfacing. The thickness of the first layer is controlled at 1.8mm, the weld overlap rate is 20%, and the interpass temperature is controlled at 140℃. The thickness of the second layer is controlled at 1.9mm, the weld overlap rate is 10%, and the interpass temperature is controlled at 19℃.

[0040] The welding process and the properties of the weld overlay are as follows: (1) The arc is stable and there is less spatter during the welding process; (2) The weld overlay prepared in Example 1 was subjected to a high-temperature corrosion test at 700℃. After 12 hours, the weight gain was 1.5g. The TP347H base material of the same size gained 2.5g after 12 hours of high-temperature corrosion at 700℃. The greater the weight gain during the high-temperature corrosion test, the worse the corrosion resistance. Therefore, the Al-based high-entropy alloy weld overlay developed in this invention has excellent high-temperature corrosion resistance. When it is welded onto the surface of the base material TP347H, it can effectively protect the base material TP347H. (3) The weld overlay prepared in Example 1 was subjected to high-temperature erosion at 600°C for 10 minutes. The weight loss after erosion was 0.41g, and the weight loss of the TP347H base material after erosion at 600°C for 10 minutes was 1.90g. During the high-temperature erosion test, the greater the weight loss, the worse the erosion resistance. Therefore, the Al-based amorphous alloy weld overlay developed in this invention has excellent high-temperature erosion resistance.

[0041] The Al-based high-entropy alloy welding wire prepared in Example 1 was used to deposit welds on the surface of a TP347H pipe. The metallographic structure of the resulting weld layer is as follows: Figure 1 As shown in the figure, the weld overlay consists of BCC phase, FCC phase (eutectic lamellar structure) and a small amount of Fe-Ti hard phase.

[0042] like Figure 2 The figure shows the cross-sectional morphology of the weld overlay layer after being deposited on the surface of a TP347H pipe using the Al-based high-entropy alloy welding wire prepared in Example 1 and subjected to a high-temperature corrosion test at 700℃ for 12 hours. As can be seen from the figure, the corrosion layer is relatively thin after 12 hours of corrosion, indicating that the weld metal has good high-temperature corrosion resistance.

[0043] like Figure 3 The figure shows the surface morphology of the weld overlay layer after a 600°C high-temperature erosion test (10 min) on the surface of a TP347H pipe, obtained by welding with the Al-based high-entropy alloy welding wire prepared in Example 1. As can be seen from the figure, the volume of weld metal that was ground off at high temperature was small, and no large-scale peeling was observed, indicating that it has excellent high-temperature wear resistance.

[0044] Example 2 A method for preparing Al-based high-entropy alloy welding wire for TP347H pipe overlay welding: Step 1: Weigh out the following components by mass percentage: Al 40.0%, Cr 20.0%, Ni 10.0%, Cu 18.0%, Ti 6.0%, with the remainder being Fe. The sum of the mass percentages of the above components should be 100%. Step 2: Place the weighed powder from Step 1 into a vacuum heating furnace and heat it at 220℃ for 3 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 3 hours. Step 3: Remove the grease from the surface of the 304 steel strip with alcohol, and wrap the flux-cored wire powder prepared in Step 2 inside the 304 steel strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm, and the filling rate of the flux-cored wire powder is controlled at 19%. Step 4: After the first drawing process is completed, the die hole diameter is reduced in sequence to finally obtain flux-cored welding wire with a diameter of 1.0~1.2mm; Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0045] A welding method using an Al-based high-entropy alloy welding wire prepared in Example 2 for surfacing TP347H pipe: Arc welding is performed on the surface of the TP347H pipe using the welding wire of this invention. The welding current is 220A, the welding voltage is 16V, and the shielding gas is 80%Ar + 20%He. Two layers are welded. The thickness of the first layer is controlled at 2.0mm, the weld overlap rate is 30%, and the interpass temperature is controlled at 130℃. The thickness of the second layer is controlled at 2.2mm, the weld overlap rate is 20%, and the interpass temperature is controlled at 80℃.

[0046] The welding process and the properties of the weld overlay are as follows: (1) The arc is stable and there is less spatter during the welding process; (2) The weld overlay prepared in Example 2 was subjected to a high-temperature corrosion test at 700°C. After 12 hours, the weight gain was 1.51g. The TP347H base material of the same area gained 2.5g after 12 hours of high-temperature corrosion at 700°C. During the high-temperature corrosion test, the greater the weight gain, the worse the corrosion resistance. Therefore, the Al-based high-entropy alloy weld overlay developed in this invention has excellent high-temperature corrosion resistance. When it is welded onto the surface of the base material TP347H, it can effectively protect the base material TP347H.

[0047] (3) The weld overlay prepared in Example 2 was subjected to high-temperature erosion at 600°C for 10 minutes. The weight loss after erosion was 0.42 g, and the weight loss of the TP347H base material after erosion at 600°C for 10 minutes was 1.90 g. During the high-temperature erosion test, the greater the weight loss, the worse the erosion resistance. Therefore, the Al-based amorphous alloy weld overlay developed in this invention has excellent high-temperature erosion resistance.

[0048] Example 3 A method for preparing Al-based high-entropy alloy welding wire for TP347H pipe overlay welding: Step 1: Weigh out the following components by mass percentage: Al 39.0%, Cr 18.0%, Ni 9.0%, Cu 17.0%, Ti 4.5%, with the remainder being Fe. The sum of the mass percentages of the above components is 100%. Step 2: Place the weighed powder from Step 1 into a vacuum heating furnace and heat it at 200℃ for 2 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 2 hours. Step 3: Remove the grease from the surface of the 304 steel strip with alcohol, and wrap the flux-cored wire powder prepared in Step 2 inside the 304 steel strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm, and the filling rate of the flux-cored wire powder is controlled at 18%. Step 4: After the first drawing process is completed, the die hole diameter is reduced in sequence to finally obtain flux-cored welding wire with a diameter of 1.0~1.2mm.

[0049] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0050] A welding method using an Al-based high-entropy alloy welding wire prepared in Example 3 for surfacing TP347H pipe: Arc welding is performed on the surface of the TP347H pipe using the welding wire of this invention. The welding current is 200A, the welding voltage is 14.5V, and the shielding gas is 80%Ar + 20%He. Two layers are welded. The thickness of the first layer is controlled at 1.9mm, the weld overlap rate is 25%, and the interpass temperature is controlled at 130℃. The thickness of the second layer is controlled at 2.05mm, the weld overlap rate is 15%, and the interpass temperature is controlled at 70℃.

[0051] The welding process and the properties of the weld overlay are as follows: (1) The arc is stable and there is less spatter during the welding process; (2) The weld overlay prepared in Example 3 was subjected to a high-temperature corrosion test at 700℃. After 12 hours, the weight gain was 1.49g. The TP347H base material of the same area gained 2.5g after 12 hours of high-temperature corrosion at 700℃. During the high-temperature corrosion test, the greater the weight gain, the worse the corrosion resistance. Therefore, the Al-based high-entropy alloy weld overlay developed in this invention has excellent high-temperature corrosion resistance. When it is welded onto the surface of the base material TP347H, it can effectively protect the base material TP347H.

[0052] (3) The weld overlay prepared in Example 3 was subjected to high-temperature erosion at 600°C for 10 minutes. The weight loss after erosion was 0.42 g, and the weight loss of the TP347H base material after erosion at 600°C for 10 minutes was 1.90 g. During the high-temperature erosion test, the greater the weight loss, the worse the erosion resistance. Therefore, the Al-based amorphous alloy weld overlay developed in this invention has excellent high-temperature erosion resistance.

[0053] Example 4 A method for preparing Al-based high-entropy alloy welding wire for TP347H pipe overlay welding: Step 1: Weigh out the following components by mass percentage: Al 38.1%, Cr 16.1%, Ni 8.1%, Cu 16.1%, Ti 3.1%, with the remainder being Fe. The sum of the mass percentages of the above components is 100%. Step 2: Place the weighed powder from Step 1 into a vacuum heating furnace and heat it at 181℃ for 1.1 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1.1 hours. Step 3: Remove the grease from the surface of the 304 steel strip with alcohol, and wrap the flux-cored wire powder prepared in Step 2 inside the 304 steel strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm, and the filling rate of the flux-cored wire powder is controlled at 20%. Step 4: After the first drawing process is completed, the die hole diameter is reduced in sequence to finally obtain flux-cored welding wire with a diameter of 1.0~1.2mm.

[0054] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0055] A welding method using an Al-based high-entropy alloy welding wire prepared in Example 4 for surfacing TP347H pipe: Arc welding is performed on the surface of the TP347H pipe using the welding wire of this invention. The welding current is 181A, the welding voltage is 13.1V, and the shielding gas is 80%Ar + 20%He. Two layers are surfacing. The thickness of the first layer is controlled at 1.81mm, the weld overlap rate is 21%, and the interpass temperature is controlled at 100℃. The thickness of the second layer is controlled at 1.91mm, the weld overlap rate is 11%, and the interpass temperature is controlled at 60℃.

[0056] The welding process and the properties of the weld overlay are as follows: (1) The arc is stable and there is less spatter during the welding process; (2) The weld overlay prepared in Example 4 was subjected to a high-temperature corrosion test at 700°C. After 12 hours, the weight gain was 1.55g. The TP347H base material of the same area gained 2.5g after 12 hours of high-temperature corrosion at 700°C. During the high-temperature corrosion test, the greater the weight gain, the worse the corrosion resistance. Therefore, the Al-based high-entropy alloy weld overlay developed in this invention has excellent high-temperature corrosion resistance. When it is welded onto the surface of the base material TP347H, it can effectively protect the base material TP347H. (3) The weld overlay prepared in Example 4 was subjected to high-temperature erosion at 600°C for 10 minutes. The weight loss after erosion was 0.45g, and the weight loss of the TP347H base material after erosion at 600°C for 10 minutes was 1.90g. During the high-temperature erosion test, the greater the weight loss, the worse the erosion resistance. Therefore, the Al-based amorphous alloy weld overlay developed in this invention has excellent high-temperature erosion resistance.

[0057] Example 5 A method for preparing Al-based high-entropy alloy welding wire for TP347H pipe overlay welding: Step 1: Weigh out Al as 38.5%, Cr as 16.5%, Ni as 8.5%, Cu as 16.5%, Ti as 3.5%, and the remainder as Fe according to the mass percentage. The sum of the mass percentages of the above components is 100%.

[0058] Step 2: Place the weighed powder from Step 1 into a vacuum heating furnace and heat it at 185℃ for 1.5 hours to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing for 1.5 hours. Step 3: Remove the grease from the surface of the 304 steel strip with alcohol, and wrap the flux-cored wire powder prepared in Step 2 inside the 304 steel strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm, and the filling rate of the flux-cored wire powder is controlled at 18.5%. Step 4: After the first drawing process is completed, the die hole diameter is reduced in sequence to finally obtain flux-cored welding wire with a diameter of 1.0~1.2mm.

[0059] Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0060] A welding method using an Al-based high-entropy alloy welding wire prepared in Example 5 for surfacing TP347H pipe: Arc welding is performed on the surface of the TP347H pipe using the welding wire of this invention. The welding current is 185A, the welding voltage is 15V, and the shielding gas is 80%Ar + 20%He. Two layers are welded. The thickness of the first layer is controlled at 1.85mm, the weld overlap rate is 22%, and the interpass temperature is controlled at 90℃. The thickness of the second layer is controlled at 1.95mm, the weld overlap rate is 12%, and the interpass temperature is controlled at 99℃.

[0061] The welding process and the properties of the weld overlay are as follows: (1) The arc is stable and there is less spatter during the welding process; (2) The weld overlay prepared in Example 5 was subjected to a high-temperature corrosion test at 700°C. After 12 hours, the weight gain was 1.57g. The TP347H base material of the same area gained 2.5g after 12 hours of high-temperature corrosion at 700°C. During the high-temperature corrosion test, the greater the weight gain, the worse the corrosion resistance. Therefore, the Al-based high-entropy alloy weld overlay developed in this invention has excellent high-temperature corrosion resistance. When it is welded onto the surface of the base material TP347H, it can effectively protect the base material TP347H. (3) The weld overlay prepared in Example 5 was subjected to high-temperature erosion at 600°C for 10 minutes. The weight loss after erosion was 0.46g, and the weight loss of the TP347H base material after erosion at 600°C for 10 minutes was 1.90g. During the high-temperature erosion test, the greater the weight loss, the worse the erosion resistance. Therefore, the Al-based amorphous alloy weld overlay developed in this invention has excellent high-temperature erosion resistance.

[0062] Example 6 A method for preparing Al-based high-entropy alloy welding wire for TP347H pipe overlay welding: Step 1: Weigh out the following components by mass percentage: Al 38.8%, Cr 16.9%, Ni 8.9%, Cu 16.9%, Ti 3.9%, with the remainder being Fe. The sum of the mass percentages of the above components is 100%. Step 2: Place the weighed powder from Step 1 into a vacuum heating furnace and heat it at 210℃ for 2.5 hours to remove the water of crystallization from the powder. After drying, place the powder into a powder mixer for thorough mixing for 2.5 hours. Step 3: Remove the grease from the surface of the 304 steel strip with alcohol, and wrap the flux-cored wire powder prepared in Step 2 inside the 304 steel strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm, and the filling rate of the flux-cored wire powder is controlled at 18%. Step 4: After the first drawing process is completed, the die hole diameter is reduced in sequence to finally obtain flux-cored welding wire with a diameter of 1.0~1.2mm; Step 5: After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

[0063] A welding method using an Al-based high-entropy alloy welding wire prepared in Example 6 for surfacing TP347H pipe: Arc welding is performed on the surface of the TP347H pipe using the welding wire of this invention. The welding current is 215A, the welding voltage is 15.5V, and the shielding gas is 80%Ar + 20%He. Two layers are welded. The thickness of the first layer is controlled at 1.95mm, the weld overlap rate is 29%, and the interpass temperature is controlled at 145℃. The thickness of the second layer is controlled at 2.15mm, the weld overlap rate is 18%, and the interpass temperature is controlled at 50℃.

[0064] The welding process and the properties of the weld overlay are as follows: (1) The arc is stable and there is less spatter during the welding process; (2) The weld overlay prepared in Example 6 was subjected to a high-temperature corrosion test at 700°C. After 12 hours, the weight gain was 1.59g. The TP347H base material of the same area gained 2.5g after 12 hours of high-temperature corrosion at 700°C. During the high-temperature corrosion test, the greater the weight gain, the worse the corrosion resistance. Therefore, the Al-based high-entropy alloy weld overlay developed in this invention has excellent high-temperature corrosion resistance. (3) The weld overlay prepared in Example 6 was subjected to high-temperature erosion at 600°C for 10 minutes. The weight loss after erosion was 0.39g, and the weight loss of the TP347H base material after erosion at 600°C for 10 minutes was 1.90g. During the high-temperature erosion test, the greater the weight loss, the worse the erosion resistance. Therefore, the Al-based high-entropy alloy weld overlay developed in this invention has excellent high-temperature corrosion resistance. When it is welded onto the surface of the base material TP347H, it can effectively protect the base material TP347H.

[0065] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: Step 1: Weigh out Al as 30%, Cr as 10%, Ni as 5%, Cu as 15%, Ti as 2%, and the remainder as Fe according to the mass percentage. The sum of the mass percentages of the above components is 100%.

[0066] The Al-based high-entropy alloy welding wire for TP347H pipe overlay welding prepared in Comparative Example 1 has weakened corrosion resistance and high-temperature erosion resistance, and cannot achieve the original design goal of this invention.

[0067] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: Step 1: Weigh out Al as 41%, Cr as 21%, Ni as 11%, Cu as 19%, Ti as 7%, and the remainder as Fe according to the mass percentage. The sum of the mass percentages of the above components is 100%.

[0068] The Al-based high-entropy alloy welding wire for TP347H pipe overlay welding prepared in Comparative Example 2 has weakened corrosion resistance and high-temperature erosion resistance, and cannot achieve the original design goal of this invention.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An Al-based high-entropy alloy welding wire for TP347H pipe overlay welding, characterized in that, The welding wire includes a flux core and a welding sheath. The flux core is composed of the following components by mass percentage: Al powder 38.0~40.0%, Cr powder 16.0~20.0%, Ni powder 8.0~10.0%, Cu powder 16.0~18.0%, Ti powder 3.0~6.0%, and the remainder is Fe powder. The sum of the mass percentages of the above components is 100%. The welding sheath is made of stainless steel. The thickness of the welding sheath is 0.2~0.6mm and the width is 5~9mm. The flux core filling rate in the welding wire is controlled at 18~20%.

2. The Al-based high-entropy alloy welding wire according to claim 1, characterized in that, The purity of Al powder is ≥99.9%, Cr powder is ≥99.9%, Ni powder is ≥99.9%, Cu powder is ≥99.9%, Ti powder is ≥99.9%, and Fe powder is ≥99.9%. The particle size of all six powders is 100~200 mesh.

3. The Al-based high-entropy alloy welding wire according to claim 1, characterized in that, The weld bead is made of 304 steel strip, with a thickness of 0.4 mm and a width of 7 mm.

4. The method for preparing the Al-based high-entropy alloy welding wire for TP347H pipe overlay welding according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Weigh out Al powder 38.0~40.0%, Cr powder 16.0~20.0%, Ni powder 8.0~10.0%, Cu powder 16.0~18.0%, Ti powder 3.0~6.0%, and the remainder is Fe powder, according to the mass percentages of the above powder components. The sum of the mass percentages of the above powder components is 100%. (2) Place the powder weighed in step 1 into a vacuum heating furnace and heat it to remove the water of crystallization from the powder; place the dried powder into a powder mixer for thorough mixing. (3) Use alcohol to remove the grease from the surface of the 304 steel strip, and wrap the powder obtained in step 2 inside the 304 steel strip using a flux-cored wire drawing device. The diameter of the first drawing die is 2.6 mm. (4) After the first drawing process is completed, the die hole diameter is reduced in sequence to finally obtain flux-cored welding wire with a diameter of 1.0~1.2mm; (5) After the flux-cored welding wire is drawn, it is wound onto the welding wire spool by a wire winding machine and finally sealed in a flux-cored welding wire vacuum packaging bag for later use.

5. The preparation method according to claim 4, characterized in that, In step (1), the purity of Al powder is ≥99.9%, the purity of Cr powder is ≥99.9%, the purity of Ni powder is ≥99.9%, the purity of Cu powder is ≥99.9%, the purity of Ti powder is ≥99.9%, the purity of Fe powder is ≥99.9%, and the particle size of the six powders is 100~200 mesh.

6. The preparation method according to claim 4, characterized in that, In step (2), the heating method is to keep the temperature at 180~220℃ for 1~3h; the mixing time is 1~3h.

7. The preparation method according to claim 4, characterized in that, In step (3), the filling rate of the flux core in the welding wire is controlled at 18~20%; the thickness of the 304 steel strip is 0.4mm and the width is 7mm.

8. The preparation method according to claim 4, characterized in that, In step (4), the mold hole diameter is set to decrease sequentially from 2.4mm, 2.2mm, 2.1mm, 1.9mm, 1.8mm, 1.7mm, 1.6mm, 1.5mm, 1.4mm, 1.3mm, 1.2mm, 1.1mm and 1.0mm.

9. The application of the Al-based high-entropy alloy welding wire according to any one of claims 1-3 or the Al-based high-entropy alloy welding wire prepared by the preparation method according to any one of claims 4-8 in the surfacing welding of TP347H pipe.

10. A welding method for Al-based high-entropy alloy welding wire used for TP347H pipe overlay welding, characterized in that, Includes the following steps: The Al-based high-entropy alloy welding wire according to any one of claims 1-3 or the Al-based high-entropy alloy welding wire prepared by any one of claims 4-8 is used for arc welding on the surface of TP347H pipe. The welding current is 180~220A, the welding voltage is 13~16V, and the shielding gas is 80%Ar+20%He. Two layers are welded. The thickness of the first layer is controlled at 1.8~2.0mm, the weld overlap rate is 20~30%, and the interpass temperature is controlled below 150℃. The thickness of the second layer is controlled at 1.9~2.2mm, the weld overlap rate is 10~20%, and the interpass temperature is controlled below 100℃.

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