A method for rapidly preparing large-size dissimilar metal gradient material by using electric-shock hot melting composition change wire

Abstract

The application discloses a method for rapidly preparing large-size heterogeneous metal gradient material by using electroslag hot melting component change drug core wire, and the method comprises three steps: preparation of component continuous change drug core wire, assembly of an electroslag hot melting device, and electroslag hot melting drug core wire forming process. In the electroslag process, the drug core wire and the melting nozzle are continuously melted in a slag pool and enter a lower metal molten pool; liquid metal in the metal molten pool is continuously solidified, and the slag pool and the metal molten pool are continuously lifted until the electroslag process is finished; and after removing a water-cooled crystallizer, the large-size heterogeneous metal gradient material is obtained. The application provides a simple, efficient and flexible method for preparing metal gradient material, and can be used for producing various different types of metal products, and effectively solves actual production problems, such as complex preparation process, high processing cost and low preparation efficiency of functional gradient material.

Description

Technical Field

[0001] This invention relates to the field of rapid preparation technology of metal gradient materials, and in particular to a method for preparing iron-based metal gradient materials by electroslag remelting of a metal-core wire with varying metal composition. Background Technology

[0002] With the rapid development of technology, engineering equipment is becoming increasingly powerful, placing higher demands on the metallic materials required for its construction. In many applications, different parts of a workpiece require different properties. For example, one side of the workpiece needs high specific strength to meet structural load-bearing requirements, while the other side needs good functionality, such as high corrosion resistance. In such cases, a single metal or alloy often cannot meet the requirements, necessitating the combination of two or more materials to satisfy the performance requirements. In practical applications, welding or hot rolling methods are often used to join two metal materials. However, the connectivity of dissimilar metals is often poor, with defects easily appearing at the interface, making it difficult to meet the required connection strength. To address this, there is a desire for different properties or functions on both sides of the same material, with a perfect combination of these different properties to prevent damage due to mismatched microstructures and properties under harsh operating conditions. Based on this need, in the 1980s, Japanese scientist Toshio Hirai first proposed the new concept of functionally gradient materials (FGM) and began research. The basic idea behind this material design concept is to select two materials with different properties according to specific requirements, and to continuously change the composition and structure of the two materials to make their internal interface disappear, thereby obtaining a heterogeneous material whose function gradually changes with the changes in composition and structure, in order to reduce and overcome the performance mismatch factors at the joint.

[0003] The main methods for preparing graded functional materials include self-propagating high-temperature synthesis (SHS), centrifugal casting, deposition methods, and additive manufacturing. SHS has low energy consumption, simple process, and good product quality, and is widely used in the preparation of ceramic-lined composite pipes and graded ceramic materials on metal surfaces. Centrifugal casting is mainly used for particle-reinforced composite materials. By changing the rotation speed, particle size, and density, the reinforcing medium is distributed in a gradient, and the volume percentage of the outer layer particles is controlled to achieve selective strengthening. This method is relatively simple, has low equipment requirements, and produces high-density castings. Deposition methods include physical vapor deposition, chemical vapor deposition, and co-deposition. These methods can prepare thin-layer graded materials with continuously varying compositions. With the rapid development of additive manufacturing technology, laser, arc, and electron beam additive manufacturing methods for preparing graded materials have attracted more attention and research. Metal heterogeneous material additive manufacturing technology can manufacture graded material parts with complex structures and fine material layouts, and the manufacturing process is simpler than traditional manufacturing methods, but the efficiency is relatively low and the equipment is complex and expensive.

[0004] In summary, current methods for preparing functionally graded metal materials each have their own characteristics and are suitable for different applications. However, they generally suffer from problems such as complex operation, high process difficulty, high cost, and inefficient preparation of large-size functionally graded metal materials. To address these issues, this invention draws on the process characteristics of flux-cored wires, electroslag welding with fused nozzles, and electroslag remelting metallurgy to propose a method for rapidly preparing large-size dissimilar functionally graded metal materials using flux-cored wires with varying compositions obtained through electroslag thermal melting.

[0005] Flux-cored welding wire: Metal powder-cored flux-cored welding wire combines the advantages of both solid and flux-cored welding wires, offering high welding efficiency, minimal spatter and fumes, and high weld quality. With technological advancements and increased production efficiency, the cost of this new type of flux-cored welding wire will continue to decrease, making it increasingly advantageous for use in production. The controllable and easy-to-prepare composition of flux-cored welding wire provides excellent technical conditions for this invention. The continuously variable composition of the flux-cored wire provides a good raw material guarantee for the preparation of metal gradient materials, while also improving the quality of the finished product.

[0006] Electroslag welding with a molten nozzle is a fusion welding method that uses the resistance heat generated by an electric current passing through conductive liquid molten slag to melt the metal (filler metal and base metal), forming a strong bond between metal atoms after solidification. The heat source for electroslag welding comes from the resistance heat of the slag pool, which can reach a maximum temperature of around 2000℃. Intense eddies are generated within the slag pool, resulting in a relatively uniform temperature distribution, thus melting the edges of the workpiece. In manufacturing, electroslag welding is used for thick plate splicing, vertical welding of blast furnaces in steel plants, and welding of large castings and forgings. It is suitable for welding in vertical positions and is mainly used for welding steel structure partitions and flanges. It is a relatively mature and advanced technology. A molten nozzle electroslag welding machine consists of a power supply, wire feeding mechanism, nozzle clamping structure, and frame. Its electrode consists of a nozzle fixed in the joint gap and welding wire continuously fed into the molten pool by the wire feeding mechanism. The welding wire from the fused nozzle can penetrate deep into the center of the weld, allowing for direct assembly of workpieces with straight edges without beveling, enabling one-time welding. Electroslag welding with a fused nozzle, as a simple and efficient process, provides favorable technical conditions for this invention.

[0007] Electroslag remelting (ESR) is a method of smelting metals using the resistance heat generated when an electric current passes through molten slag. ESR is used to purify metals, primarily to obtain clean, uniform, and dense steel ingots. Steel produced through ESR has high purity, low sulfur content, few non-metallic inclusions, and a smooth, clean, uniform, and dense ingot surface. The as-cast mechanical properties of ESR steel can meet or exceed the specifications of forgings of the same steel grade. The quality of ESR steel ingots depends on a reasonable ESR process and the equipment conditions that ensure the ESR process. ESR technology is a crucial technology in this invention, providing excellent technical support for obtaining pure, uniform, and dense metallic materials. Summary of the Invention

[0008] Addressing the shortcomings of existing metal functional graded material (FJPM) preparation technologies, and drawing upon the process characteristics of flux-cored wires, electroslag welding with fused nozzles, and electroslag remelting metallurgy, this invention addresses the technical problem of rapidly preparing large-size dissimilar metal graded materials using electroslag thermal melting of flux-cored wires with varying compositions. The chemical composition of the flux-cored wire can be easily adjusted; by continuously changing the composition ratio, flux-cored wires with continuously varying compositions can be obtained. The flux-cored wire is then heated and melted in an electroslag bath to form a molten metal pool of a certain volume. This molten metal pool solidifies continuously in a water-cooled crystallizer of a specific shape, ultimately yielding a large-size metal graded material with continuously varying compositions. Because the molten metal pool has a certain volume, the liquid metal flows fully within it, further ensuring the uniformity of composition in the microscopic local areas of the graded material, thereby avoiding the formation of dissimilar metal interfaces.

[0009] The entire process flow diagram of the preparation method is as follows:Figure 1 As shown in the process flow diagram, there are three main steps in preparing electroslag melt flux core wire samples: preparing flux core wire with continuously changing composition, assembling the electroslag melt device, and forming the electroslag melt flux core wire.

[0010] The specific preparation method is as follows:

[0011] Step 1) Preparation of a continuously variable composition core filament: The core filament is prepared using the "steel strip method". Based on the concept of differential calculus and combined with the calculation of the molten pool mass, the unit weight of the powder is determined. The composition of the powder in each unit is uniform, and the composition of the powder in adjacent units changes in a gradient according to the design. After the steel strip is cold-bent into a U-shaped tube, the powder from adjacent units is added sequentially and continuously, then closed into an O-shaped tube. After multiple drawing operations, a continuously variable composition core filament is obtained as a whole.

[0012] Step 2) Assemble the electroslag melting device: The electroslag melting device includes a power supply 1, a wire feeding mechanism 2, a parameter control panel 3, a melting nozzle 4, and a water-cooled crystallizer 5; the bottom of the water-cooled crystallizer 5 is an inlet plate 51, one end of the power supply 1 is connected to the inlet plate 51, and the other end is connected to the upper end of the melting nozzle 4, with the lower end of the melting nozzle 4 vertically inserted above the inlet plate 51; the power supply provides energy for the electroslag process; the wire feeding mechanism and the parameter control panel are integrated on the welding carriage;

[0013] Step 3) Electroslag melt flux core wire forming process:

[0014] In the initial stage, the end of the flux-cored wire 6 is first fed to the top of the inlet plate 51 at the bottom of the water-cooled crystallizer 5, and a small amount of flux is laid on the inlet plate 51. The power supply 1 is turned on, and an electric arc is generated between the flux-cored wire 6 and the inlet plate 51 to melt the flux. Flux is continuously added, and after a stable slag pool 7 is formed, the electric arc is extinguished, and the electroslag process begins. The slag pool 7 is located above the molten metal pool 8. The flux-cored wire 6 and the melting nozzle 4 are continuously melted in the slag pool 7 and enter the molten metal pool 8 below. The liquid metal in the molten metal pool 8 is continuously solidified, and the slag pool 7 and the molten metal pool 8 continue to rise until the electroslag process ends. The water-cooled crystallizer 5 is removed, and the slag skin on the metal surface is cleaned off to obtain a larger-sized metal gradient material with the same shape as the cavity of the water-cooled crystallizer, i.e., the formed metal 54.

[0015] As a preferred embodiment of the above technical solution, the present invention provides a method for rapidly preparing large-size dissimilar metal gradient materials using electroslag remelting of composition-changing flux-cored wires, which further includes some or all of the following technical features:

[0016] As an improvement to the above technical solution, in step 1), due to the agitation of the liquid metal in the molten pool when the flux core wire is melted by electroslag melting, the abrupt change in the composition of the flux powder at the junction of adjacent units in the flux core wire is eliminated.

[0017] As an improvement to the above technical solution, in step 2), the upper end of the melting nozzle 4 is clamped below the wire feeding wheel of the wire feeding mechanism 2 and connected to the power supply 1, while the other end of the melting nozzle 4 extends into the liquid slag pool inside the water-cooled crystallizer 5.

[0018] As an improvement to the above technical solution, in step 2), the upper end of the melting nozzle 4 is clamped below the wire feeding wheel of the wire feeding mechanism 2 and connected to the power supply 1 through the conductive rod 9.

[0019] As an improvement to the above technical solution, in step 2), the shape of the water-cooled crystallizer can be designed according to the size and shape requirements of the product, such as a cylindrical or cubic shape.

[0020] As an improvement to the above technical solution, in step 2), the water-cooled crystallizer 5 is made of a water-cooled copper block 52 containing flowing cooling water 53 inside.

[0021] As an improvement to the above technical solution, in step 3), the added flux just forms a slag pool, which covers and extinguishes the electric arc.

[0022] As an improvement to the above technical solution, the resulting dissimilar metal gradient material can be further processed such as rolling and forging according to its microstructure and performance characteristics and application requirements.

[0023] As an improvement to the above technical solution, the present invention provides a method for preparing iron-based metal gradient materials. Based on traditional, high-precision, and mass-producible electroslag remelting and electroslag welding processes, and utilizing relevant principles, iron-based metal gradient materials such as carbon steel-stainless steel and stainless steel with different alloy compositions are prepared, providing a new approach to achieve different properties in different parts of the material.

[0024] This invention establishes an equipment platform for preparing metal gradient materials using electroslag remelting of flux-cored wires. The composition of the flux-cored wires is controllable and easy to prepare; the electroslag welding operation of the melting nozzle is simple and suitable for forming deep, long vertical welds; electroslag remelting can refine metals, and the product size and microstructure are controllable. This invention's experimental platform integrates the advantages and characteristics of these three processing methods, enabling the rapid, simple, and efficient preparation of high-quality metal gradient materials under relatively simple equipment and process conditions, significantly reducing process costs and demonstrating high practical value and innovative significance.

[0025] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0026] 1) Higher production efficiency: Electroslag remelting casting can heat metal quickly, and water-cooled crystallizers can cool molten metal quickly, making the entire production process more efficient. Flux-cored wire is of better quality than other welding wires, which can also improve production efficiency.

[0027] 2) High purity, stable quality, and uniform gradient transition: The electroslag metallurgical effect of the molten metal pool can further purify the metal and isolate it from air, preventing oxidation or other contaminants from entering the metal. Simultaneously, because the molten metal pool has a certain volume, the full flow of liquid metal within it can further ensure the uniformity of composition in the microscopic local areas of the gradient material, thereby avoiding the formation of dissimilar metal interfaces.

[0028] 3) Adjustable composition and wide range of applications: During the preparation of flux-cored welding wire, the composition of the powder can be adjusted. By changing the composition of different alloying elements, flux-cored wires with varying compositions can be made, which has a wide range of applications. At the same time, electroslag remelting is very suitable for processing various types of metals and is very beneficial for preparing metal gradient materials.

[0029] 4) Simple operation: Compared with other methods for preparing functionally graded materials, the electroslag welding with a melting nozzle used in this invention can eliminate the need to constantly adjust the height of the conductive rod, making the electroslag process simple and reliable.

[0030] In summary, this invention provides a simple, efficient, and flexible method for preparing metal gradient materials, which can be used to produce various types of metal products. It effectively solves practical production problems such as complex preparation processes, high processing costs, and low preparation efficiency of functionally graded materials.

[0031] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, the following detailed description is provided in conjunction with preferred embodiments. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0033] Figure 1 This is a process flow diagram of the method for rapidly preparing large-size dissimilar metal gradient materials using electroslag thermal melting of flux-cored wires with varying composition, as described in this invention.

[0034] Figure 2 This is a schematic diagram of the apparatus for rapidly preparing large-size dissimilar metal gradient materials using electroslag thermal melting of flux-cored wires with varying composition, as described in this invention.

[0035] Figure 3 This is a schematic diagram of the water-cooled crystallizer forming process of the method for rapidly preparing large-size dissimilar metal gradient materials by using electroslag thermal melting of flux-cored wire with changing composition, as described in this invention.

[0036] Figure 4This is a top view of a cylindrical water-cooled crystallizer used in the method for rapidly preparing large-size dissimilar metal gradient materials by utilizing electroslag thermal melting of flux-cored wires with varying compositions, as described in this invention.

[0037] In the diagram: 1-Power supply, 2-Wire feeding mechanism, 3-Parameter control panel, 4-Melting nozzle, 5-Water-cooled crystallizer, 51-Introduction plate, 52-Water-cooled copper block, 53-Cooling water, 54-Formed metal, 6-Core wire, 7-Slag pool, 8-Melting pool, 9-Conductive rod. Detailed Implementation

[0038] The following detailed description of specific embodiments of the present invention is part of this specification. The principles of the present invention are illustrated through examples, and other aspects, features and advantages of the present invention will become apparent from this detailed description.

[0039] Example 1

[0040] A method for preparing a carbon steel-stainless steel composition-tunable gradient material includes the following steps:

[0041] 1) The finished product is a cuboid (40mm long, 30mm wide, and 80mm high at the bottom). The composition variation areas along the height of the finished product are determined as follows: 0-40mm is the carbon steel area, and 40mm-80mm is the stainless steel area. Carbon steel-stainless steel flux-cored welding wire (wire diameter φ3.2mm) is prepared. The flux-cored wire powder is selected. The composition of the flux-cored wire for the carbon steel part is: 0.21% C, 0.33% Mn, 0.018% Si, and 0.015% P. The composition of the flux-cored wire for the stainless steel part is: 0.072% C, 0.94% Mn, 0.038% Si, 0.022% P, 12.59% Cr, 4.63% Ni, 0.62% Mo, and 0.24% Cu. The composition of each area is clearly marked on the steel strip. After the powders of different areas are mixed evenly, they are assembled into the steel strip of the corresponding area. Rolling, drawing, and winding are then started. The preparation of the carbon steel-stainless steel flux-cored welding wire is completed.

[0042] 2) Assemble the rectangular water-cooled crystallizer (the bottom surface of the inner cooling cavity is 40mm long, 30mm wide, and 90mm high; the outer bottom surface is 100mm long, 90mm wide, and 90mm high; the thickness of the cooling water circulation area is 20mm), and check the sealing of the inlet and outlet.

[0043] 3) Check whether the connections of the power supply, die head, melting nozzle, and wire feeding mechanism are normal;

[0044] 4) Add the flux-cored welding wire into the wire feeding mechanism;

[0045] 5) One end of the welding nozzle is clamped below the conductive rod of the welding machine and connected to the power supply, while the other end of the welding nozzle extends into the top of the bottom of the water-cooled crystallizer;

[0046] 6) Turn on the power, adjust the welding parameters in the parameter control panel, set the welding current and wire feeding speed, start feeding the wire, and stop feeding the wire when the welding wire extends 3mm out of the melting nozzle.

[0047] 7) Turn on the water-cooled crystallizer switch, and open both the inlet and outlet simultaneously to introduce flowing cooling water;

[0048] 8) Start electroslag melting. Spread a small amount of flux onto the inlet plate. The flux layer thickness is about 10-15mm. After igniting the arc, add a small amount of flux until a liquid slag pool is formed and extinguish the arc. As the electroslag process proceeds, the liquid level in the slag pool continues to rise, and the melting nozzle continuously melts and enters the slag pool. When the melting nozzle melts at 80mm, turn off the power. Finally, a carbon steel-stainless steel gradient material is formed.

[0049] 9) After the metal material has solidified in the crystallizer, turn off the power to the crystallizer and disassemble the water-cooled crystallizer;

[0050] 10) Clean the slag on the metal surface to obtain a carbon steel-stainless steel gradient material that matches the shape of the crystallizer cavity.

[0051] Example 2

[0052] A method for preparing a ferritic stainless steel-martensitic stainless steel composition-tunable gradient material includes the following steps:

[0053] 1) The finished product is cylindrical (bottom diameter φ40mm, height 100mm). The compositional variation range along the height of the finished product is determined: 0-50mm is the ferritic stainless steel region, and 50mm-100mm is the martensitic stainless steel region. Ferritic stainless steel-martensitic stainless steel flux-cored welding wire (wire diameter φ4mm) is prepared. The calculated lengths of the flux-cored welding wire for the ferritic stainless steel section are 5m and for the martensitic stainless steel section are 6m (considering the limitations of the wire feeding mechanism, an extra 1m is needed for clamping and ensuring continuous wire feeding). The flux-cored wire powder is selected, with the ferritic stainless steel section flux-cored wire composition being: 0.050% C. The composition of the flux-cored welding wire for martensitic stainless steel segments is: 0.060% C, 0.97% Mn, 0.045% Si, 0.018% P, 11.61% Cr, 4.75% Ni, 0.58% Mo, and 0.25% Cu. The composition of each region is clearly marked on the steel strip. After the powder from different regions is evenly mixed, it is assembled into the corresponding region of the steel strip. Rolling, drawing, and winding then begin, completing the preparation of the ferritic stainless steel-martensitic stainless steel flux-cored welding wire.

[0054] 2) Assemble the cylindrical water-cooled crystallizer (outer diameter) Inner circular cavity diameter (Height is 110mm, cooling water circulation area thickness is 20mm), check the sealing of the inlet and outlet;

[0055] 3) Check whether the connections of the power supply, die head, melting nozzle, and wire feeding mechanism are normal;

[0056] 4) Add the flux-cored welding wire into the wire feeding mechanism;

[0057] 5) One end of the welding nozzle is clamped below the conductive rod of the welding machine and connected to the positive terminal of the power supply, while the other end of the welding nozzle extends into the top of the bottom of the water-cooled crystallizer.

[0058] 6) Turn on the power, adjust the welding parameters in the parameter control panel, set the welding current and wire feeding speed, start feeding the wire, and stop feeding the wire when the welding wire extends 3mm out of the melting nozzle.

[0059] 7) Turn on the water-cooled crystallizer switch, and open both the inlet and outlet simultaneously to introduce flowing cooling water;

[0060] 8) Start electroslag melting. Spread a small amount of flux onto the inlet plate. The flux layer thickness is about 10-15mm. After ignition, add a small amount of flux until a liquid slag pool is formed and extinguish the arc. As the electroslag process proceeds, the liquid level in the slag pool rises continuously. The molten nozzle continuously melts and enters the slag pool. When the molten nozzle melts at 100mm, turn off the power. Finally, a ferritic stainless steel-martensitic stainless steel gradient material is formed.

[0061] 9) After the metal material has solidified in the crystallizer, turn off the power to the crystallizer and disassemble the water-cooled crystallizer;

[0062] 10) Clean the slag on the metal surface to obtain a ferritic stainless steel-martensitic stainless steel gradient material that matches the shape of the crystallizer cavity.

[0063] This invention addresses the lack of rapid preparation methods for large-size iron-based metal gradient materials, which are widely used in the chemical industry. Based on the process characteristics of flux-cored wire, electroslag welding of melting nozzles, and electroslag remelting metallurgy, this invention proposes a method for rapidly preparing large-size dissimilar metal gradient materials using flux-cored wires with varying compositions obtained through electroslag thermal melting. This method can effectively prepare iron-based metal gradient materials such as carbon steel-stainless steel and stainless steels with different alloy compositions. Furthermore, the composition ratio of the flux-cored wire can be adjusted accordingly to meet the performance requirements of different products.

[0064] All the raw materials listed in this invention, as well as the upper and lower limits and ranges of the raw materials and the upper and lower limits and ranges of the process parameters (such as temperature, time, etc.), can realize this invention. Examples are not listed one by one here.

[0065] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for rapidly preparing large-size dissimilar metal gradient materials using electroslag remelting of a flux-cored wire with varying composition, characterized in that, The method includes the following steps: Step 1) Preparation of core wire with continuously changing composition: The core wire is prepared by the "steel strip method". Based on the differential idea and the calculation of the mass of the molten pool, the unit weight of the powder is determined. The composition of the powder in each unit is uniform and consistent. The composition of the powder in adjacent units changes in a gradient according to the design. After the steel strip is cold-bent into a U-shaped tube, the powder of adjacent units is added in sequence. Then it is closed into an O-shaped tube. After multiple drawing, the core wire with continuously changing composition is obtained as a whole (6). Step 2) Assemble the electroslag hot melting device: The electroslag hot melting device includes a power supply (1), a wire feeding mechanism (2), a parameter control panel (3), a melting nozzle (4), and a water-cooled crystallizer (5); the bottom of the water-cooled crystallizer (5) is an inlet plate (51), one end of the power supply (1) is connected to the inlet plate (51), and the other end is connected to the upper end of the melting nozzle (4). The lower end of the melting nozzle (4) is vertically inserted above the inlet plate (51); The power supply provides energy for the electroslag process; the wire feeding mechanism and parameter control panel are integrated into the welding carriage; Step 3) Electroslag melt flux core wire forming process: In the initial stage, the end of the flux-cored wire (6) is first sent to the top of the inlet plate (51) at the bottom of the water-cooled crystallizer (5), and a small amount of flux is laid on the inlet plate (51). When the power supply (1) is turned on, an electric arc is generated between the flux-cored wire (6) and the inlet plate (51) and the flux is melted. Flux is continuously added, and after a stable slag pool (7) is formed, the electric arc is extinguished and the electroslag process begins. The slag pool (7) is located above the molten metal pool (8). The flux-cored wire (6) and the nozzle (4) are continuously melted in the slag pool (7) and enter the molten metal pool (8) below. The liquid metal in the molten metal pool (8) is continuously solidified, and the slag pool (7) and the molten metal pool (8) continue to rise until the electroslag process ends. The water-cooled crystallizer (5) is removed, and the slag skin on the metal surface is cleaned off. A larger size metal gradient material with the same shape as the cavity of the water-cooled crystallizer can be obtained.

2. The method for rapidly preparing large-size dissimilar metal gradient materials using electroslag remelting of composition-changing flux-cored wires as described in claim 1, characterized in that, In step 1), due to the agitation of the liquid metal in the molten pool during the electroslag melting of the flux core wire, the abrupt change in the composition of the flux powder at the junction of adjacent units in the flux core wire is eliminated.

3. The method for rapidly preparing large-size dissimilar metal gradient materials using electroslag remelting of composition-changing flux-cored wires as described in claim 1, characterized in that... In step 2), the upper end of the melting nozzle (4) is clamped below the wire feeding wheel of the wire feeding mechanism (2) and connected to the power supply (1), while the other end of the melting nozzle (4) extends into the liquid slag pool inside the water-cooled crystallizer (5).

4. The method for rapidly preparing large-size dissimilar metal gradient materials using electroslag remelting of composition-changing flux-cored wires as described in claim 1, characterized in that, In step 2), the upper end of the melting nozzle (4) is clamped below the wire feeding wheel of the wire feeding mechanism (2) and connected to the power supply (1) through the conductive rod (9).

5. The method for rapidly preparing large-size dissimilar metal gradient materials using electroslag remelting of a flux-cored wire with varying composition, as described in claim 1, is characterized in that... In step 2), the shape of the water-cooled crystallizer is designed according to the size and shape requirements of the product, including a cylinder or a cube.

6. The method for rapidly preparing large-size dissimilar metal gradient materials using electroslag remelting of composition-changing flux-cored wires as described in claim 1, characterized in that, In step 2), the water-cooled crystallizer (5) is made of a water-cooled copper block (52) containing flowing cooling water (53) inside.

7. The method for rapidly preparing large-size dissimilar metal gradient materials using electroslag remelting of a flux-cored wire with varying composition, as described in claim 1, is characterized in that... In step 3), the added flux just forms a slag pool, which covers and extinguishes the electric arc.

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