A seamless flux-cored wire and a method of manufacturing the same

Abstract

The present application provides a kind of seamless flux-cored wire and its preparation method, specifically relates to welding material field.The seamless flux-cored wire of the present application includes steel band skin and the medicine core filled in the steel band skin, the raw material composition of the medicine core and the weight percentage of each component are: 30-50wt% of rutile, 2-4wt% of potassium titanate, 2-4wt% of feldspar, 1-3wt% of quartz, 8-12wt% of manganese silicon alloy, 6-10wt% of low carbon manganese iron, 1-2wt% of aluminum magnesium alloy, 1.5-3wt% of aluminum iron, 10-12wt% of nickel powder, 2-3wt% of molybdenum iron, 1.5-3wt% of sodium fluoroaluminate, 2-3.5wt% of titanium iron, 0.2-0.6wt% of low boron iron, 1-2wt% of calcium zirconium lanthanum, and the balance of iron powder.The seamless flux-cored wire of the present application has stable arc, less spatter, excellent all-position welding process when welding, and the deposited metal not only has excellent strength and low temperature toughness, but also has low diffusible hydrogen content, which is suitable for 690Mpa long-distance pipeline automatic welding.

Description

Technical Field

[0001] This invention relates to the field of welding materials, and more specifically to a seamless flux-cored welding wire and its preparation method. Background Technology

[0002] Long-distance pipelines refer to pipelines used to transport commercial media between production sites, storage facilities, and user units, primarily for transporting crude oil, refined oil, natural gas, and liquefied petroleum gas. In the flat sections of oil and gas pipeline projects, the fully automated gas-shielded solid wire welding process is mainly used, meaning that the welding process from the root to the filler and capping is completed using mechanized and automated welding equipment. However, in some special sections of the pipeline project, such as mountainous areas, coastal areas, plateaus, and joint welds, the automated gas-shielded flux-cored wire welding process is mainly used. Because the steel pipes in trunk pipeline projects typically have high strength levels, such as L555M and L485M grade pipeline steel, the welding materials are required to have high strength, high toughness, and all-position welding process performance. In some low-temperature areas, the welding materials also need to meet low-temperature impact toughness requirements of -45℃ or even lower.

[0003] Currently, there are few varieties of high-strength flux-cored welding wires for long-distance pipelines in China, and the country mainly relies on imports. Traditional flux-cored welding wires are prone to moisture absorption, have high hydrogen diffusion, and are prone to cracking after welding. Developing high-strength flux-cored welding wires for long-distance pipelines is an urgent need for the development of welding materials. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a seamless flux-cored welding wire and its preparation method to improve the problems of traditional flux-cored welding wires being prone to moisture absorption, high diffusible hydrogen, and easy cracking after welding.

[0005] To achieve the above and other related objectives, the present invention provides a seamless flux-cored welding wire, comprising a steel strip outer sheath and a flux core filled within the steel strip outer sheath. The raw material composition and weight percentage of each component of the flux core are as follows: rutile 30-50 wt%, potassium titanate 2-4 wt%, feldspar 2-4 wt%, quartz 1-3 wt%, manganese silicon alloy 8-12 wt%, low-carbon ferromanganese 6-10 wt%, aluminum-magnesium alloy 1-2 wt%, aluminum iron 1.5-3 wt%, nickel powder 10-12 wt%, ferromolybdenum 2-3 wt%, sodium fluoroaluminate 1.5-3 wt%, ferrotitanium 2-3.5 wt%, low-boron iron 0.2-0.6 wt%, calcium zirconium lanthanum 1-2 wt%, and the balance being iron powder.

[0006] In one example of the present invention, the rutile contains ≥95wt% titanium dioxide (TiO2), the potassium titanate contains ≥65wt% TiO2, the feldspar contains 63-73wt% silicon dioxide (SiO2), the quartz contains ≥97wt% SiO2, the manganese silicon alloy contains 62-67wt% manganese (Mn), the low-carbon ferromanganese contains ≥80wt% Mn, the aluminum magnesium alloy contains 47-53wt% aluminum (Al), the ferroaluminum contains 48-52wt% Al, the nickel powder contains ≥99wt% nickel (Ni), the ferromolybdenum contains ≥55wt% molybdenum (Mo), the sodium fluoroaluminate (Na3AlF6) has a purity ≥93%, the ferrotitanium titanate contains 25-35wt% titanium (Ti), the low-boron ferroaluminate contains 0.9-1.1wt% boron (B), and the calcium zirconium lanthanum contains 40-43wt% lanthanum (La).

[0007] In one example of the present invention, the weight percentages of each component in the steel strip sheath are as follows: carbon (C) content ≤ 0.04 wt%, manganese (Mn) content 0.10~0.25 wt%, silicon (Si) content ≤ 0.015 wt%, phosphorus (P) content ≤ 0.010 wt%, and sulfur (S) content ≤ 0.008 wt%.

[0008] In one example of the present invention, the outer sheath of the steel strip is made of HS5 low-carbon steel strip.

[0009] In one example of the present invention, the weight of the flux core is 14-16% of the total weight of the seamless flux-cored wire.

[0010] In one example of the present invention, the diameter of the seamless flux-cored wire is 1.2~1.6 mm.

[0011] This invention also provides a method for preparing a seamless flux-cored welding wire, comprising the following steps:

[0012] Weigh each component of the core according to the formula, dry each component and mix them evenly to obtain the core.

[0013] The steel strip is rolled into a U-shaped groove, the core is filled into the U-shaped groove, closed, and welded.

[0014] The seamless flux-cored welding wire is obtained by drawing and reducing the diameter of the steel strip filled with flux to the required specifications.

[0015] In one example of the present invention, the drying process of each component of the core includes: holding manganese silicon alloy, low-carbon manganese iron, aluminum iron, nickel powder, molybdenum iron, titanium iron, low-boron iron, and iron powder at 160~180℃ for 115~125min; holding feldspar, quartz, calcium zirconium lanthanum at 390~410℃ for 355~365min; and holding rutile at 840~860℃ for 355~365min.

[0016] The seamless flux-cored welding wire of this invention uses a rutile slag system. By adding appropriate amounts of alloying elements such as Mn, Si, Ni, Mo, and La, the number of acicular ferrite in the weld is increased, the grains are refined, the weld is purified, and the strength and low-temperature toughness of the weld are guaranteed. The addition of appropriate amounts of potassium titanate, feldspar, sodium fluoroaluminate, and calcium zirconium lanthanum ensures less spatter, a stable arc, and excellent all-position welding performance during welding. Simultaneously, the seamless flux-cored welding wire production process ensures that the diffusible hydrogen content of the deposited metal is below 4 mL / 100g, which not only reduces moisture absorption problems caused by storage and transportation but also effectively improves the crack resistance of the weld. Therefore, the seamless flux-cored welding wire of this invention can perform all-position welding, has good wire feeding stability, and is suitable for automated welding of 690 MPa long-distance pipelines. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating the preparation process of the seamless flux-cored welding wire of the present invention in one embodiment. Detailed Implementation

[0019] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of the present invention is for describing specific implementation schemes and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0020] In this document, when numerical ranges are mentioned, unless otherwise specified, the distribution of selectable values ​​within a numerical range is considered continuous, including the two endpoints of the range (i.e., the minimum and maximum values), and every value between these two endpoints. When multiple numerical ranges are provided to describe a feature or property, these numerical ranges can be combined.

[0021] It should be noted that, unless otherwise specified, "%" and "wt%" in this article both represent mass percentages.

[0022] The seamless flux-cored welding wire of the present invention comprises a steel strip outer sheath and a flux core filled within the steel strip outer sheath. The raw material composition of the flux core and the weight percentage of each component are as follows: rutile 30~50wt%, potassium titanate 2~4wt%, feldspar 2~4wt%, quartz 1~3wt%, manganese silicon alloy 8~12wt%, low carbon ferromanganese 6~10wt%, aluminum magnesium alloy 1~2wt%, aluminum iron 1.5~3wt%, nickel powder 10~12wt%, ferromolybdenum 2~3wt%, sodium fluoroaluminate 1.5~3wt%, ferrotitanium 2~3.5wt%, low boron iron 0.2~0.6wt%, calcium zirconium lanthanum 1~2wt%, and the balance being iron powder.

[0023] The functions of each component in the flux-cored welding wire of this application are as follows:

[0024] Rutile: Primarily used for slag formation and arc stabilization. It reduces spatter, improves weld surface quality, and ensures good all-position welding performance of the welding wire.

[0025] Potassium titanate: Potassium titanate comprises titanium dioxide and potassium oxide. Titanium dioxide not only helps stabilize the arc, reduce spatter, and improve the stability of the welding process, but also helps optimize the microstructure of the weld metal, improving its mechanical properties. Potassium oxide helps improve the plasticity of the weld metal, making it less prone to cracking under welding stress.

[0026] Feldspar: A slag-forming agent. Adding an appropriate amount can adjust the viscosity of the molten slag, improve the weld formation, and ensure the realization of all-position welding.

[0027] Quartz: Its main function is to form slag and stabilize the arc. Adding an appropriate amount can increase the activity of the slag and adjust the melting point and viscosity of the molten slag.

[0028] Manganese-silicon alloy: It is the main deoxidizer and also has the effect of alloying, maintaining the strength and toughness of the deposited metal.

[0029] Low-carbon ferromanganese: Its main functions are deoxidation, desulfurization, and solid solution strengthening.

[0030] Aluminum-magnesium alloys: Al and Mg in them act as strong deoxidizers, which can reduce the oxygen content of the weld and reduce porosity. Adding an appropriate amount can improve the welding processability and increase the impact toughness.

[0031] Aluminum-iron: Deoxidizer; adding an appropriate amount can improve weld formation and increase the gloss of the weld surface.

[0032] Nickel powder: Nickel is used as a diffusion alloy to reduce proeutectoid ferrite in weld metal, increase acicular ferrite, improve austenite stability, and enhance the weld's resistance to intergranular corrosion.

[0033] Ferromolybdenum: It is mainly used for alloying, which can introduce Mo into the weld, refine the grains, improve the weld strength and low-temperature toughness, and prevent crack sensitivity.

[0034] Sodium fluoroaluminate: Its main function is dehydrogenation, preventing weld cracks.

[0035] Titanium iron: refines the weld seam, generates needle-like ferrite, and improves the toughness of the weld seam structure.

[0036] Low-boron iron: Boron is a grain-refining element commonly used in carbon steel and low-alloy steel, which can significantly improve the impact toughness of welds and the strength of deposited metal.

[0037] Calcium, zirconium, and lanthanum: mainly used for deoxidation and microalloying, purifying weld seams and refining grains.

[0038] The steel strip sheath, as the outer layer of the flux-cored wire, protects the internal flux powder. It not only prevents the flux powder from being contaminated, damp, or otherwise damaged during transportation, storage, and use, but also provides necessary mechanical support to ensure that the flux powder does not scatter or deform during welding. Furthermore, the steel strip sheath and the flux core work together to enhance the strength and toughness of the weld. Through appropriate alloying elements and process control, the weld can achieve excellent mechanical properties and corrosion resistance. The combination of the steel strip sheath and flux powder optimizes weld formation, making the weld more aesthetically pleasing and smooth, and reducing welding defects.

[0039] In one embodiment, the rutile contains ≥95wt% TiO2, the potassium titanate contains ≥65wt% TiO2, the feldspar contains 63-73wt% SiO2, the quartz contains ≥97wt% SiO2, the manganese silicon alloy contains 62-67wt% Mn, the low-carbon ferromanganese contains ≥80wt% Mn, the aluminum magnesium alloy contains 47-53wt% Al, the aluminum ferromanganese contains 48-52wt% Al, the nickel powder contains ≥99wt% Ni, the ferromolybdenum contains ≥55wt% Mo, the sodium fluoroaluminate contains ≥93wt% Na3AlF6, the ferrotitanium ilmenite contains 25-35wt% Ti, the low-boron ferromanganese contains 0.9-1.1wt% B, and the calcium zirconium lanthanum contains 40-43wt% La.

[0040] In one embodiment, the weight percentages of each component in the steel strip sheath are as follows: C content ≤ 0.04 wt%, Mn content 0.10~0.25 wt%, Si content ≤ 0.015 wt%, P content ≤ 0.010 wt%, and S content ≤ 0.008 wt%. In this embodiment, the steel strip sheath is made of HS5 low-carbon steel strip. HS5 low-carbon steel strip is a steel with a low carbon content, exhibiting good weldability and toughness. As the sheath of flux-cored welding wire, it ensures the stability and continuity of the welding wire during the welding process. Simultaneously, HS5 low-carbon steel strip also possesses certain strength and corrosion resistance, protecting the flux-cored welding wire from damage caused by the external environment. In other embodiments, other types of steel strip can also be selected for the steel strip sheath, provided that the content of each trace element meets the usage requirements.

[0041] In one embodiment, the weight of the flux core is 14 to 16% of the total weight of the seamless flux-cored wire, for example, 14%, 15% or 16%.

[0042] In one embodiment, the diameter of the seamless flux-cored wire of this application is 1.2~1.6mm, for example 1.2mm, 1.4mm or 1.6mm.

[0043] Please see Figure 1 This invention provides a method for preparing a seamless flux-cored welding wire, comprising the following steps:

[0044] S1. Weigh each component of the core according to the ratio, dry each component and mix them evenly to obtain the core.

[0045] S2. Roll the steel strip into a U-shaped groove, fill the core into the U-shaped groove, close it, and weld it together;

[0046] S3. The steel strip filled with flux is drawn and reduced in diameter to the required specification to obtain the seamless flux-cored welding wire.

[0047] In step S1, the components of the core are weighed according to the following proportions: rutile 30-50 wt%, potassium titanate 2-4 wt%, feldspar 2-4 wt%, quartz 1-3 wt%, manganese silicon alloy 8-12 wt%, low-carbon manganese iron 6-10 wt%, aluminum magnesium alloy 1-2 wt%, aluminum iron 1.5-3 wt%, nickel powder 10-12 wt%, molybdenum iron 2-3 wt%, sodium fluoroaluminate 1.5-3 wt%, titanium iron 2-3.5 wt%, low-boron iron 0.2-0.6 wt%, calcium zirconium lanthanum 1-2 wt%, and the balance being iron powder. The drying treatment of each component of the core is as follows: manganese silicon alloy, low-carbon manganese iron, aluminum iron, nickel powder, molybdenum iron, titanium iron, low-boron iron, and iron powder are kept at 160~180℃ for 115~125min; feldspar, quartz, and calcium zirconium lanthanum are kept at 390~410℃ for 355~365min; and rutile is kept at 840~860℃ for 355~365min. After drying, the above components are mixed evenly.

[0048] In step S2, the steel strip outer sheath contains ≤0.04wt% C, 0.10~0.25wt% Mn, ≤0.015wt% Si, ≤0.010wt% P, and ≤0.008wt% S. In one embodiment, the steel strip outer sheath is made of HS5 low-carbon steel strip. Rolling the steel strip into a U-shaped groove, filling it with flux core, closing it, and welding it all employ conventional techniques in the art. The filling rate of the seamless flux-cored wire, i.e., the weight of the flux core, is 14~16% of the total weight of the seamless flux-cored wire, for example, 14%, 15%, or 16%.

[0049] In step S3, the diameter of the seamless flux-cored wire of this application is 1.4~1.6mm, for example 1.4mm, 1.5mm or 1.6mm.

[0050] The technical solution of the present invention will be described in detail below through several specific embodiments. Unless otherwise stated, the raw materials and reagents used in the following embodiments are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the embodiments are all commercially available.

[0051] Example 1

[0052] In this embodiment, the seamless flux-cored welding wire includes a steel strip outer sheath and a flux core filled within the steel strip outer sheath. In this embodiment, the steel strip outer sheath is made of HS5 low-carbon steel strip, and the thickness × width of the steel strip outer sheath is 0.3mm × 10mm. First, the components of the flux core are weighed according to the following ratio: rutile 30wt%, potassium titanate 4wt%, feldspar 4wt%, quartz 1wt%, manganese silicon alloy 12wt%, low-carbon ferromanganese 10wt%, aluminum-magnesium alloy 1wt%, aluminum iron 3wt%, nickel powder 11wt%, ferromolybdenum 3wt%, sodium fluoroaluminate 3wt%, ferrotitanium 3.5wt%, low-boron iron 0.2wt%, calcium zirconium lanthanum 2wt%, and iron powder 12.3wt%. Then, manganese silicon alloy, low-carbon ferromanganese, ferroaluminum, nickel powder, ferromolybdenum, ferrotitanium, low-boron ferrometallurgical, and iron powder are heated at 170℃ for 120 min. Feldspar, quartz, and calcium zirconium lanthanum are heated at 390℃ for 365 min, and rutile is heated at 840℃ for 365 min. The dried components are then mixed evenly to obtain the flux core. A steel strip is rolled into a U-shaped groove, the flux core is filled into the U-shaped groove, the U-shaped groove is closed and welded, and finally the flux-filled steel strip is drawn and reduced in diameter to the required specification to obtain a seamless flux-cored welding wire. In this embodiment, the flux core filling rate is 14%, and the diameter of the seamless flux-cored welding wire is 1.2 mm.

[0053] Example 2

[0054] In this embodiment, the seamless flux-cored welding wire includes a steel strip outer sheath and a flux core filled within the steel strip outer sheath. In this embodiment, the steel strip outer sheath is made of HS5 low-carbon steel strip, and the thickness × width of the steel strip outer sheath is 0.3mm × 10mm. First, the components of the flux core are weighed according to the following ratio: rutile 36wt%, potassium titanate 3wt%, feldspar 2wt%, quartz 2wt%, manganese silicon alloy 10wt%, low-carbon ferromanganese 8wt%, aluminum-magnesium alloy 1.5wt%, aluminum iron 2wt%, nickel powder 12wt%, ferromolybdenum 2.5wt%, sodium fluoroaluminate 2.5wt%, ferrotitanium 3wt%, low-boron iron 0.3wt%, calcium zirconium lanthanum 1.5wt%, and iron powder 13.7wt%. Then, manganese silicon alloy, low-carbon ferromanganese, ferroaluminum, nickel powder, ferromolybdenum, ferrotitanium, low-boron ferrometallurgical, and iron powder are heated at 180℃ for 115 minutes. Feldspar, quartz, and calcium zirconium lanthanum are heated at 400℃ for 360 minutes, and rutile is heated at 840℃ for 365 minutes. The dried components are then mixed evenly to obtain the flux core. A steel strip is rolled into a U-shaped groove, the flux core is filled into the U-shaped groove, the U-shaped groove is closed and welded, and finally the flux-filled steel strip is drawn and reduced in diameter to the required specification to obtain a seamless flux-cored welding wire. In this embodiment, the flux core filling rate is 15%, and the diameter of the seamless flux-cored welding wire is 1.4 mm.

[0055] Example 3

[0056] In this embodiment, the seamless flux-cored welding wire includes a steel strip outer sheath and a flux core filled within the steel strip outer sheath. In this embodiment, the steel strip outer sheath is made of HS5 low-carbon steel strip, and the thickness × width of the steel strip outer sheath is 0.3mm × 10mm. First, the components of the flux core are weighed according to the following ratio: rutile 40wt%, potassium titanate 2.5wt%, feldspar 3wt%, quartz 3wt%, manganese silicon alloy 11wt%, low-carbon ferromanganese 9wt%, aluminum-magnesium alloy 2wt%, aluminum iron 1.5wt%, nickel powder 10wt%, ferromolybdenum 2wt%, sodium fluoroaluminate 1.5wt%, ferrotitanium 2.5wt%, low-boron iron 0.5wt%, calcium zirconium lanthanum 1wt%, and iron powder 10.5wt%. Then, manganese silicon alloy, low-carbon ferromanganese, ferroaluminum, nickel powder, ferromolybdenum, ferrotitanium, low-boron ferrometallurgical, and iron powder are heated at 160℃ for 125 min. Feldspar, quartz, and calcium zirconium lanthanum are heated at 410℃ for 355 min. Rutile is heated at 850℃ for 360 min. The dried components are then mixed evenly to obtain the flux core. A steel strip is rolled into a U-shaped groove. The flux core is filled into the U-shaped groove, which is then closed and welded. Finally, the flux-filled steel strip is drawn and reduced in diameter to the required specifications to obtain a seamless flux-cored welding wire. In this embodiment, the flux core filling rate is 16%, and the diameter of the seamless flux-cored welding wire is 1.6 mm.

[0057] Example 4

[0058] In this embodiment, the seamless flux-cored welding wire includes a steel strip outer sheath and a flux core filled within the steel strip outer sheath. In this embodiment, the steel strip outer sheath is made of HS5 low-carbon steel strip, and the thickness × width of the steel strip outer sheath is 0.3mm × 10mm. First, the components of the flux core are weighed according to the following ratio: rutile 50wt%, potassium titanate 2wt%, feldspar 2wt%, quartz 1wt%, manganese silicon alloy 8wt%, low-carbon ferromanganese 6wt%, aluminum-magnesium alloy 1wt%, aluminum-iron 2wt%, nickel powder 11wt%, ferromolybdenum 2wt%, sodium fluoroaluminate 1.5wt%, ferrotitanium 2wt%, low-boron ferrometallurgical 0.6wt%, calcium zirconium lanthanum 1wt%, and iron powder 9.9wt%. Then, manganese silicon alloy, low-carbon ferromanganese, ferroaluminum, nickel powder, ferromolybdenum, ferrotitanium, low-boron ferrometallurgical, and iron powder are heated at 170℃ for 120 min. Feldspar, quartz, and calcium zirconium lanthanum are heated at 400℃ for 360 min, and rutile is heated at 860℃ for 355 min. The dried components are then mixed evenly to obtain the flux core. A steel strip is rolled into a U-shaped groove, the flux core is filled into the U-shaped groove, the U-shaped groove is closed and welded, and finally the flux-filled steel strip is drawn and reduced in diameter to the required specification to obtain a seamless flux-cored welding wire. In this embodiment, the flux core filling rate is 16%, and the diameter of the seamless flux-cored welding wire is 1.6 mm.

[0059] The content of each component in the flux core of the seamless flux-cored welding wires prepared in Examples 1 to 4 is shown in Table 1. Welding was carried out using the seamless flux-cored welding wires prepared in Examples 1 to 4 according to the welding process parameters in Table 2. The properties of the deposited metal and the welding processability are shown in Table 3.

[0060] Table 1: Flux-cored component content in flux-cored wires of Examples 1 to 4

[0061]

[0062] Table 2: Welding process parameters for Examples 1 to 4

[0063]

[0064] Table 3: Deposited Metal Properties and Welding Processability of Seamless Flux-Cored Welding Wires in Examples 1 to 4

[0065]

[0066] As can be seen from the results in Table 3, the seamless flux-cored welding wire provided by this invention exhibits excellent mechanical properties of the deposited metal. The tensile strength of the deposited metal is not less than 670 MPa, the yield strength is not less than 750 MPa, and the elongation after fracture is approximately 20%, effectively reducing residual welding stress. The weld has higher plasticity and fracture toughness, reducing the sensitivity to cold cracking. The impact energy at -60℃ is ≥82 J, indicating that the flux-cored welding wire of this invention also has good toughness at low temperatures. Moreover, the seamless flux-cored welding wire of this invention has excellent toughness and good fatigue performance of the welded joint, effectively improving the formation of cold cracks in welding. The arc is stable during welding, with less spatter, and excellent all-position welding process.

[0067] The seamless flux-cored welding wire of this invention uses a rutile slag system. By adding appropriate amounts of alloying elements such as Mn, Si, Ni, Mo, and La, the number of acicular ferrite in the weld is increased, the grains are refined, the weld is purified, and the strength and low-temperature toughness of the weld are guaranteed. The addition of appropriate amounts of potassium titanate, feldspar, sodium fluoroaluminate, and calcium zirconium lanthanum ensures less spatter, a stable arc, and excellent all-position welding performance during welding. Simultaneously, the seamless flux-cored welding wire production process ensures that the diffusible hydrogen content of the deposited metal is below 4 mL / 100g, which not only reduces moisture absorption problems caused by storage and transportation but also effectively improves the crack resistance of the weld. Therefore, the seamless flux-cored welding wire of this invention can perform all-position welding, has good wire feeding stability, and is suitable for automated welding of 690 MPa long-distance pipelines. Thus, this invention effectively overcomes some practical problems in the prior art, and therefore has high utilization value and application significance.

[0068] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A seamless flux cored welding wire characterized by, The seamless flux-cored wire comprises a steel belt sheath and a flux core filled in the steel belt sheath, and the raw material composition and the weight percentage of each component of the flux core are as follows: 30-50wt% of rutile, 2-4wt% of potassium titanate, 2-4wt% of feldspar, 1-3wt% of quartz, 8-12wt% of manganese-silicon alloy, 6-10wt% of low-carbon manganese iron, 1-2wt% of aluminum-magnesium alloy, 1.5-3wt% of aluminum-iron, 10-12wt% of nickel powder, 2-3wt% of molybdenum iron, 1.5-3wt% of sodium fluoroaluminate, 2-3.5wt% of titanium iron, 0.2-0.6wt% of low-boron iron, 1-2wt% of calcium-zirconium-lanthanum, and the balance of iron powder, wherein the content of lanthanum in the calcium-zirconium-lanthanum is 40-43wt%, and the weight of the flux core is 14-16% of the total weight of the seamless flux-cored wire.

2. The seamless flux cored wire of claim 1, wherein The content of titanium dioxide in the rutile is ≥95wt%, the content of silicon dioxide in the feldspar is 63-73wt%, the content of silicon dioxide in the quartz is ≥97wt%, the content of manganese in the manganese-silicon alloy is 62-67wt%, the content of manganese in the low-carbon manganese iron is ≥80wt%, the content of aluminum in the aluminum-magnesium alloy is 47-53wt%, the content of aluminum in the aluminum-iron is 48-52wt%, the content of nickel in the nickel powder is ≥99wt%, the content of molybdenum in the molybdenum iron is ≥55wt%, the purity of the sodium fluoroaluminate is ≥93wt%, the content of titanium in the titanium iron is 25-35wt%, and the content of boron in the low-boron iron is 0.9-1.1wt%.

3. The seamless flux cored wire of claim 1, wherein The weight percentage of each component in the steel belt sheath is as follows: the content of carbon is ≤0.04wt%, the content of manganese is 0.10-0.25wt%, the content of silicon is ≤0.015wt%, the content of phosphorus is ≤0.010wt%, and the content of sulfur is ≤0.008wt%.

4. The seamless flux cored wire of claim 1 wherein, The steel belt sheath is selected from HS5 low-carbon steel belts.

5. The seamless flux cored wire of claim 1 wherein, The diameter of the seamless flux-cored wire is 1.2-1.6mm.

6. A method of producing the seamless flux-cored wire as claimed in any one of claims 1 to 5, characterized by, The method comprises the following steps: The components of the flux core are weighed according to the proportion, dried, and then mixed uniformly to obtain the flux core; The steel belt is rolled into a U-shaped groove, the flux core is filled into the U-shaped groove, and the U-shaped groove is closed and welded; The steel belt filled with the flux core is drawn to the required specification to obtain the seamless flux-cored wire.

7. The production method according to claim 6, characterized by, The drying treatment of the components of the flux core comprises the following steps: the manganese-silicon alloy, the low-carbon manganese iron, the aluminum-iron, the nickel powder, the molybdenum iron, the titanium iron, the low-boron iron, and the iron powder are treated at 160-180℃ for 115-125min; the feldspar, the quartz, and the calcium-zirconium-lanthanum are treated at 390-410℃ for 355-365min; and the rutile is treated at 840-860℃ for 355-365min.

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