A flux-cored wire for a wear-resistant coating of a dredging pipeline and a method of manufacturing the same

Abstract

The application discloses a flux-cored wire for wear-resistant coating of dredging pipes and a preparation method thereof, which is composed of a sheath and a core, and is used for robot MIG, and has excellent mechanical properties and good hardness. The metal flux-cored wire core alloy component is composed of the following components in percentage by mass: Cr: 16.0-18.0%, C: 4.3-8.0%, Ti: 5.43-9.0%, Ni: 1.9-3.0%, TiC: 15.0-20.0%, Mn: 1.3-1.5%, Si: 0.4-0.5%, B: 4.6-7.85%, and the balance of Fe and inevitable impurities, and the sum of the above components is 100%. In the working process, the hardness of the cladding layer can reach 59HRC at most, and the shearing property of the cladding layer and the base material can reach 620MPa.

Description

Technical Field

[0001] This invention belongs to the field of welding materials technology, and relates to a flux-cored welding wire for wear-resistant coating of dredging pipelines and its preparation method. Background Technology

[0002] Dredged pipelines face the scouring of high-pressure, high-speed fluids and the erosion of silt and corrosive media in marine engineering, river dredging, and port construction, making wear resistance and corrosion resistance particularly important. Traditional wear-resistant coating materials are prone to cracking, deformation, and insufficient adhesion during welding, affecting coating performance and lifespan. Developing welding materials suitable for wear-resistant coatings on dredged pipelines has become a research focus. New wear-resistant coating welding materials must possess high hardness and excellent wear resistance, while maintaining thermal and chemical stability under high-temperature welding conditions and exhibiting good weldability.

[0003] In practical applications, high-performance wear-resistant coated welding materials have been validated in dredgers and port dredging equipment, significantly improving service life and maintenance costs, and enhancing engineering efficiency and safety. Flux-cored welding wire consists of an outer steel strip and an inner flux core containing alloy powder, deoxidizers, and arc stabilizers, which melt under the action of an electric arc to form a deposited metal with specific properties. Through arc surfacing technology, flux-cored welding wire can form a high-hardness, high-wear-resistant weld overlay layer on the surface of dredged pipelines, effectively resisting fluid erosion and particulate wear. Therefore, flux-cored welding wire is a welding material with very broad development prospects and has wide applications in wear-resistant surfacing; however, currently available iron-based wear-resistant welding wires generally lack sufficient hardness, and the prepared coatings are prone to cracking. Summary of the Invention

[0004] Given the current state of limited domestic technology, this invention introduces a wear-resistant coated flux-cored welding material specifically designed for dredging pipelines. This invention significantly extends service life and reduces maintenance costs, thereby improving project efficiency and safety.

[0005] The first technical solution of the present invention is a flux-cored welding wire for wear-resistant coating of dredging pipelines, comprising an outer sheath and a flux core, wherein the flux core is composed of the following components by mass percentage: Cr: 16.0-18.0%, C: 4.3-8.0%, Ti: 5.43-9.0%, Ni: 1.9-3.0%, TiC: 15.0-20.0%, Mn: 1.3-1.5%, Si: 0.4-0.5%, B: 4.6-7.85%, with the balance being Fe and unavoidable impurities, and the sum of the mass percentages of the above components being 100%.

[0006] The outer sheath material of the welding wire is low-carbon steel strip, which comprises, by mass percentage: C: 0.021%, Mn: 0.15%, Si: 0.19%, with the remainder being Fe.

[0007] The chemical composition of the welding wire in this invention is designed based on the following: Cr: The introduction of chromium (Cr) is a major highlight in the development of wear-resistant coated flux-cored welding wire for dredged pipelines. As an important alloying element, Cr possesses extremely high hardness and excellent wear resistance, making it key to improving the wear resistance of the welding wire. When Cr is added to the flux-cored welding wire, it reacts with the substrate during welding to form a hard chromium carbide protective layer. This protective layer not only effectively resists friction and wear generated during dredging but also significantly increases the hardness of the welded area. Furthermore, the addition of Cr optimizes the microstructure of the welding wire, increasing the number and more uniform distribution of carbides, resulting in a good strength-toughness match with the matrix, thereby further improving wear resistance and ensuring the dredged pipeline remains efficient, safe, and stable during long-term operation.

[0008] Carbon (C) plays a crucial role in the design of flux-cored welding wires for wear-resistant coatings in dredged pipelines. The design is based on the significant impact of carbon content on wear resistance and microstructure. Appropriately increasing the carbon content can promote the formation of hard phases, such as carbides, in the welding wire. These hard phases significantly improve the hardness and wear resistance of the wear-resistant coating. Simultaneously, carbon also affects the ratio of γ-Fe matrix to hard phases in the welding wire's microstructure. By precisely controlling the carbon content, the distribution of the matrix and hard phases can be optimized, allowing the wear-resistant coating to maintain high hardness while also possessing good toughness and crack resistance. This meets the wear resistance requirements of dredged pipelines in complex operating environments, extends their service life, and improves the overall efficiency of the project.

[0009] Titanium (Ti) plays a crucial role in the design of wear-resistant coated flux-cored welding wires for dredged pipelines. This design is based on Ti's ability to effectively enhance the wire's hardness, wear resistance, and microstructure stability. As an alloying element, Ti reacts with carbon (C) to form a hard titanium carbide phase, significantly improving the hardness and wear resistance of the weld layer. Simultaneously, the addition of Ti optimizes the wire's microstructure, resulting in a more uniform carbide distribution and improved overall mechanical properties of the weld layer. Furthermore, Ti refines the grain size, increasing the density and crack resistance of the microstructure, further enhancing the wire's wear resistance and service life. This ensures that dredged pipelines maintain good wear resistance even in harsh operating environments, improving the reliability and safety of the project.

[0010] Ni (nickel) plays a crucial role in the design of wear-resistant coated flux-cored welding wires for dredged pipelines. The design is primarily based on Ni's ability to effectively improve the wire's corrosion resistance and toughness, while also enhancing its wear resistance. The addition of Ni significantly improves the weld's resistance to thermal cracking and corrosion, especially in harsh environments such as seawater and chemical corrosion, enabling the wire to adapt to more complex operating conditions. Furthermore, Ni optimizes the wire's microstructure by refining grains and strengthening the matrix, thereby improving the overall hardness and wear resistance of the weld layer. Therefore, the addition of Ni not only enhances the wire's durability but also improves the overall safety and reliability of the project, ensuring that the dredged pipeline maintains excellent wear resistance during long-term use.

[0011] TiC (titanium carbide) plays a crucial reinforcing role in the design of wear-resistant coated flux-cored wires for dredging pipelines. This design is based on TiC's high hardness, high wear resistance, and good chemical stability. As a hard phase, the addition of TiC significantly improves the wire's hardness and wear resistance, effectively resisting friction and abrasion during dredging operations. Simultaneously, the uniform distribution of TiC particles within the weld layer forms a dense protective layer, enhancing its corrosion resistance and anti-stripping properties. Furthermore, TiC optimizes the wire's microstructure, improving the bonding strength between the matrix and the hard phase, ensuring the stability and reliability of the weld layer under complex stress environments. Therefore, the introduction of TiC is a crucial basis for designing high-performance wear-resistant coated flux-cored wires for dredging pipelines.

[0012] Manganese (Mn) plays a crucial role in the design of wear-resistant coated flux-cored welding wires for dredging pipelines. This design is based on the fact that Mn effectively enhances the hardness, strength, and wear resistance of the welding wire. Mn can form high-temperature compounds with other elements in the welding wire, increasing its melting temperature and stability. Simultaneously, Mn reacts with oxygen to generate volatile manganese oxides, inhibiting porosity and improving weld quality. Furthermore, the addition of Mn optimizes the microstructure of the welding wire, improving the hardenability and toughness of the matrix. This allows the weld layer to maintain high hardness while also possessing good toughness and crack resistance, thus meeting the wear-resistant requirements of dredged pipelines in complex operating environments.

[0013] Silicon (Si) plays a crucial role in the design of wear-resistant coated flux-cored welding wires for dredging pipelines. The design is primarily based on Si's ability to effectively improve the welding performance and wear resistance of the wire. Si lowers the melting point of the wire, improves the fluidity of the molten pool, and promotes the formation and stabilization of the molten pool, thereby increasing welding efficiency and quality. Simultaneously, as a deoxidizing element, Si prevents iron from combining with oxides, reducing oxide inclusions in the cladding layer and improving its purity and mechanical properties. Furthermore, Si enhances the hardness and wear resistance of the weld layer, enabling the welding wire to better resist wear during dredging operations and extend the pipeline's service life. Therefore, the inclusion of Si is an important consideration in the design of high-performance wear-resistant coated flux-cored welding wires for dredging pipelines.

[0014] Boron (B) plays a crucial role in the design of flux-cored welding wires for wear-resistant coatings on dredged pipelines. B is a chemical component that enhances the wear resistance of welding wires, offering multifaceted improvements in this area. Increased wear resistance is essential for dredged pipelines, which frequently endure wear and erosion. The addition of B can help optimize the metallographic structure of the welding wire, making it more refined. A refined metallographic structure typically improves the hardness and wear resistance of the weld overlay, which is beneficial for enhancing the overall performance of the dredged pipeline. By adjusting the B content in the welding wire, the hardness and toughness of the weld overlay can be balanced. Appropriate hardness ensures wear resistance, while sufficient toughness prevents brittle fracture under impact or vibration.

[0015] TiB2: TiB2 (titanium diboride) is a high-hardness, high-wear-resistance ceramic material. When added to flux-cored welding wire, it generates a large number of TiC-TiB2 particles in the weld overlay alloy through a metallurgical reaction. These particles are dispersed in the primary carbides and matrix, thus significantly improving the hardness and wear resistance of the weld overlay alloy. This is crucial for dredged pipelines, which frequently endure wear and erosion; improved wear resistance can extend the pipeline's service life.

[0016] The second technical solution of this invention is: a method for preparing flux-cored welding wire for wear-resistant coating of dredging pipelines, the specific steps of which are as follows: Step 1: First, prepare the components of the core into a powder of ≤100 mesh. Then, weigh the core powder according to the following mass percentages: Cr: 16.0-18.0%, C: 4.3-8.0%, Ti: 5.43-9.0%, Ni: 1.9-3.0%, TiC: 15.0-20.0%, Mn: 1.3-1.5%, Si: 0.4-0.5%, B: 4.6-7.85%, with the balance being Fe and unavoidable impurities. The sum of the mass percentages of the above components is 100%.

[0017] Step 2, Drying: Heat the alloy powder weighed in Step 1 to 160-210 degrees Celsius in a vacuum tube furnace and keep it at that temperature for 2 hours; Step 3: Fill the U-shaped groove of the low carbon steel strip with the core powder obtained in step 2, with a filling rate of 23wt%~27wt%, and make it into 1.20mm welding wire after passing through the closed forming roller.

[0018] The second technical solution of this invention is also characterized by: The dried powder in step 2 is heated and kept warm in a vacuum tube furnace under an argon atmosphere; The low-carbon steel strip in step 3 has a width of 7mm and a thickness of 0.3mm; A method for using a wear-resistant coated flux-cored welding wire for dredging pipelines, wherein welding is performed under the following conditions: voltage 20-23V, current 110-180A, and wire extension length 12-18mm.

[0019] The welding method used is robotic MIG welding.

[0020] The beneficial effects of this invention are: 1. This invention provides a wear-resistant coated flux-cored welding wire for dredging pipelines, which has a short preparation cycle, high production efficiency, and can be mass-produced; 2. The metal powder-cored wire of this invention has good processability and excellent weld formation. Special alloy components are added to the flux-cored wire, which can form hard carbides or other hard phases during welding, significantly improving the hardness and wear resistance of the weld layer.

[0021] 3. This invention provides a welding process using robotic MIG and metal powder-cored wire as raw material; during the welding process, the flux core is uniform and the arc is stable, which can greatly improve the wear resistance and service life of the weld, and the weld formation is beautiful with virtually no collapse. Attached Figure Description

[0022] Figure 1 This is a microstructure diagram of Example 4 of the present invention. Detailed Implementation

[0023] As described in the background section, there is currently a lack of domestic and international manufacturers of novel wear-resistant coating welding materials with high hardness and excellent wear resistance. Traditional wear-resistant coating materials are prone to cracking, deformation, and insufficient adhesion during welding, affecting coating performance and lifespan. Therefore, this invention proposes a flux-cored welding wire for wear-resistant coatings in dredging pipelines and its preparation method. The invention will now be further described in conjunction with specific implementation methods.

[0024] Example 1 Step 1: First, prepare the components of the core into a powder with a mesh size ≤100. Then, weigh the core powder according to the following mass percentages: Cr: 16.58%, C: 4.4%, Ti: 5.48%, Ni: 2.10%, TiC: 18.7%, Mn: 1.36%, Si: 0.41%, B: 4.75%, with the balance being Fe and unavoidable impurities. The sum of the mass percentages of the above components is 100%. The low-carbon steel strip has a width of 7mm and a thickness of 0.3mm.

[0025] Step 2, Drying: Heat the alloy powder weighed in Step 1 to 160-210 degrees Celsius in a vacuum tube furnace and keep it at that temperature for 2 hours; Step 3: Fill the U-shaped groove of the low carbon steel strip with the core powder obtained in Step 2, with a filling rate of 23wt%, and make it into 1.20mm welding wire after passing through the closed forming roll.

[0026] A method for using a wear-resistant coated flux-cored welding wire for dredging pipelines, wherein welding is performed under the following conditions: voltage 20V, current 121A, and wire extension length 13mm.

[0027] Example 1: This welding wire is specifically designed for dredging pipelines, using high-quality flux-cored material to ensure a stable arc during welding and a uniform and robust coating. Through meticulous processing, the welding wire effectively avoids defects such as porosity and slag inclusions during welding, while also preventing issues like incomplete fusion or penetration, ensuring the integrity and reliability of the weld. The resulting wear-resistant coating possesses extremely high hardness and wear resistance, effectively resisting erosion and wear during dredging. The shear strength of the resulting cladding layer to the substrate reaches 601 MPa, and the hardness reaches 51 HRC, meeting the usage requirements.

[0028] Example 2 Step 1: First, prepare the components of the core into a powder with a mesh size of ≤100. Then, weigh the core powder according to the following mass percentages: Cr: 16.96%, C: 4.50%, Ti: 5.69%, Ni: 2.23%, TiC: 19.2%, Mn: 1.43%, Si: 0.43%, B: 4.95%, with the balance being Fe and unavoidable impurities. The sum of the mass percentages of the above components is 100%. The low-carbon steel strip has a width of 7mm and a thickness of 0.3mm.

[0029] Step 2, Drying: Heat the alloy powder weighed in Step 1 to 160-210 degrees Celsius in a vacuum tube furnace and keep it at that temperature for 2 hours; Step 3: Fill the U-shaped groove of the low carbon steel strip with the core powder obtained in Step 2, with a filling rate of 24wt%, and make it into 1.20mm welding wire after passing through the closed forming roll.

[0030] A method for using a wear-resistant coated flux-cored welding wire for dredging pipelines, wherein welding is performed at a voltage of 21V, a current of 128A, and a wire extension length of 14mm.

[0031] Example 2: This welding wire is specifically designed for dredging pipelines, using high-quality flux-cored material to ensure a stable arc during welding and a uniform and robust coating. Through meticulous processing, the welding wire effectively avoids defects such as porosity and slag inclusions during welding, while also preventing issues like incomplete fusion or penetration, ensuring the integrity and reliability of the weld. The resulting wear-resistant coating possesses extremely high hardness and wear resistance, effectively resisting erosion and wear during dredging. The shear strength of the resulting cladding layer to the substrate reaches 587 MPa, and the hardness reaches 53 HRC, meeting the usage requirements.

[0032] Example 3 Step 1: First, prepare the components of the core into a powder with a mesh size of ≤100. Then, weigh the core powder according to the following mass percentages: Cr: 17.3%, C: 4.71%, Ti: 5.87%, Ni: 2.64%, TiC: 19.34%, Mn: 1.48%, Si: 0.48%, B: 5.68%, with the balance being Fe and unavoidable impurities. The sum of the mass percentages of the above components is 100%. The low-carbon steel strip has a width of 7mm and a thickness of 0.3mm.

[0033] Step 2, Drying: Heat the alloy powder weighed in Step 1 to 160-210 degrees Celsius in a vacuum tube furnace and keep it at that temperature for 2 hours; Step 3: Fill the U-shaped groove of the low carbon steel strip with the core powder obtained in step 2, with a filling rate of 25wt%, and make it into 1.20mm welding wire after passing through the closed forming roll.

[0034] A method for using a wear-resistant coated flux-cored welding wire for dredging pipelines, wherein welding is performed at a voltage of 22V, a current of 135A, and a wire extension length of 15mm.

[0035] Example 3: This welding wire is specifically designed for dredging pipelines, using high-quality flux-cored material to ensure a stable arc during welding and a uniform and robust coating. Through meticulous processing, the welding wire effectively avoids defects such as porosity and slag inclusions during welding, while also preventing issues like incomplete fusion or penetration, ensuring the integrity and reliability of the weld. The resulting wear-resistant coating possesses extremely high hardness and wear resistance, effectively resisting erosion and wear during dredging. The shear strength of the resulting cladding layer to the substrate reaches 598 MPa, and the hardness reaches 54 HRC, meeting the usage requirements.

[0036] Example 4 Step 1: First, prepare the components of the core into a powder with a mesh size of ≤100. Then, weigh the core powder according to the following mass percentages: Cr: 18.0%, C: 5.0%, Ti: 6.0%, Ni: 3.0%, TiC: 20.0%, Mn: 1.5%, Si: 0.5%, B: 6.98%, with the balance being Fe and unavoidable impurities. The sum of the mass percentages of the above components is 100%. The low-carbon steel strip has a width of 7mm and a thickness of 0.3mm.

[0037] Step 2, Drying: Heat the alloy powder weighed in Step 1 to 160-210 degrees Celsius in a vacuum tube furnace and keep it at that temperature for 2 hours; Step 3: Fill the U-shaped groove of the low carbon steel strip with the core powder obtained in step 2, with a filling rate of 23wt%~27wt%, and make it into 1.20mm welding wire after passing through the closed forming roller.

[0038] A method for using a wear-resistant coated flux-cored welding wire for dredging pipelines, wherein welding is performed at a voltage of 23V, a current of 140A, and a wire extension length of 16mm.

[0039] Example 4: This welding wire is specifically designed for dredging pipelines, using high-quality flux-cored material to ensure a stable arc during welding and a uniform and robust coating. Through meticulous processing, the welding wire effectively avoids defects such as porosity and slag inclusions during welding, while also preventing issues like incomplete fusion or penetration, ensuring the integrity and reliability of the cladding layer. The resulting wear-resistant coating possesses extremely high hardness and wear resistance, effectively resisting erosion and wear during dredging. The shear strength of the resulting cladding layer to the substrate reaches 620 MPa, and the hardness reaches 59 HRC, meeting the usage requirements.

[0040] The microstructure of the cladding layer of the metal powder core wire prepared according to Example 4 is as follows: Figure 1 Clearly demonstrated, the cladding layer exhibits a network structure with fine titanium carbide particles within, enhancing the hardness of the wear-resistant coating. The cladding layer obtained in this example achieves a shear strength of 620 MPa and a hardness of 59 HRC with the substrate. In dredging environments, it resists abrasion from silt and gravel. Furthermore, due to its high shear strength, the wear-resistant coating is difficult to detach, significantly extending the service life of the dredged pipeline.

[0041] The addition of boron (B) forms TiB2, increasing the nucleation rate and resulting in a greater number and more uniform distribution of primary carbides. This leads to a decrease in the ratio of primary carbide spacing to abrasive grain size. When the primary carbide spacing is close to the abrasive grain size, the abrasive grains perform little or no cutting wear on the matrix, eliminating the cutting effect on the matrix and effectively protecting the matrix structure. Simultaneously, the addition of TiB increases the matrix area, leading to a corresponding increase in the amount of martensite and retained austenite. The increased amount of retained austenite also improves the wear resistance of the weld overlay alloy to some extent. Furthermore, the welding metallurgical reaction during the welding process forms a large number of TiC-TiB black hard phase particles, which are embedded within the microstructure. These particles have strong bonding with the carbides and matrix, making them less likely to detach from the carbides and matrix during wear, thus hindering wear and giving the weld overlay alloy relatively high resistance to plastic deformation, thereby improving wear resistance.

Claims

1. A method for preparing a flux-cored welding wire for a wear-resistant coating of dredging pipelines, characterized in that, The flux-cored wire comprises an outer sheath and a flux core, the flux core consisting of the following components by weight percentage: composition: Cr：16.0-18.0%， C：4.3 -8.0%， Ti: 5.43-9.0%, Ni: 1.9-3.0%, TiC: 15.0-20.0%, Mn: 1.3-1.5%, Si: 0.4-0.5%, B: 4.6-7.85%, balance being Fe and unavoidable impurities; the sum of the mass percentages of the above components is 100%. The outer sheath material is low-carbon steel strip, which comprises, by mass percentage: C: 0.021%, Mn: 0.15%, Si: 0.19%, with the remainder being Fe; The specific steps of this preparation method are as follows: Step 1: After preparing the components of the core into powder of ≤100 mesh, weigh out the core powder according to the mass percentage. Step 2, Drying: Heat the alloy powder weighed in Step 1 to 160-210 degrees Celsius in a vacuum tube furnace and keep it at that temperature for 2 hours; Step 3: Fill the U-shaped groove of the low carbon steel strip with the core powder obtained in step 2, with a filling rate of 23wt%~27wt%, and make it into 1.20mm welding wire after passing through the closed forming roll.

2. The method for preparing the flux-cored welding wire for wear-resistant coating of dredging pipelines according to claim 1, characterized in that, In step 3, the outer skin is a low-carbon steel strip with a width of 7mm and a thickness of 0.3mm.

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