Layered-structure low-splashing flux-cored wire and preparation method thereof

Abstract

The invention belongs to the technical field of welding materials, discloses a layered-structure low-splashing flux-cored wire and a preparation method thereof, and solves the problems of serious splashing and poor welding seam performance caused by discontinuous action of an arc stabilizer, insufficient molten pool core deoxidation and coarse welding seam grains of an existing flux-cored wire. The welding wire comprises a low-carbon steel strip metal outer skin and a layered flux core (an outer layer and an inner layer), wherein the outer layer flux core is located on the inner surface of the outer skin, accounts for 8-12% of the total mass of the welding wire, and comprises a mesoporous SiO2-KI compound, a CaF2-MgO-La2O3 composite slag former and the like; the center of the outer layer is filled with the inner layer flux core, the inner layer flux core accounts for 10%-18% of the total mass of the welding wire, TiC-coated ZrB2 core-shell particles (relay deoxidation and grain refinement), Fe-Sc-Ti alloy powder (collaborative deoxidation) and the like are contained, and the total proportion of the inner layer and the outer layer is 18%-26%. Compared with a traditional welding wire, the splashing amount is reduced by 30%, the tensile strength of a welding seam is improved by 20% or above, and the flux-cored wire is innovative.

Description

Technical Field

[0001] This invention belongs to the field of welding materials technology, specifically relating to a layered structure low-spatter flux-cored welding wire and its preparation method. Background Technology

[0002] Welding is a core joining process in equipment manufacturing, construction engineering, and other fields. Flux-cored welding wire has become one of the mainstream consumables in the welding field due to its balance between welding efficiency and process adaptability, as well as its flexible composition adjustment during preparation. However, welding spatter remains a key issue restricting the further application of this technology: on the one hand, spatter causes direct loss of metal materials and requires additional time to clean welding residue, significantly increasing production costs; on the other hand, spatter can also lead to defects such as porosity and slag inclusions in the weld, directly causing a decrease in the tensile strength of the welded joint and affecting the safety and reliability of structural components.

[0003] The core cause of spatter is the violent escape of carbon monoxide (CO) gas from the weld pool: Under the action of a high-temperature arc above 3000K, oxygen in the weld pool (mainly from the oxide film of the welding wire, flux-cored impurities, and the welding atmosphere) reacts with carbon to generate CO. CO expands rapidly at high temperatures, and if its escape rate exceeds the constraint of the surface tension of the weld pool, it will carry molten metal and form spatter. Although existing flux-cored welding wires have been improved by adding deoxidizers, arc stabilizers, and other components, the following key technical problems still exist, resulting in poor spatter control: (1) Low and unstable deoxidation efficiency, and difficult to control CO generation: Traditional welding wire relies on elemental Ti and Mn for deoxidation. Elemental Ti is easy to oxidize and form TiO2 film in the early stage of preparation or welding, resulting in the loss of most of the effective deoxidizing components. At the same time, Ti will also form coarse inclusions with N and S in the molten pool at high temperature. These inclusions will become channels for CO to escape. In addition, a single deoxidizer cannot adapt to the oxygen concentration difference in different areas of the molten pool, resulting in large fluctuations in CO generation concentration, which ultimately leads to high and unstable welding spatter. (2) Poor sustained effect of arc stabilizer, increased arc fluctuation and spatter: The arc stabilizer KI (boiling point 1330℃) added to the existing welding wire is much lower than the arc temperature (3000~6000K). KI will volatilize rapidly in the early stage of welding, and by the later stage of welding, the core component for arc stabilization (K) will have diminished. + When the ions are almost depleted, the arc energy distribution becomes uneven and the droplet transition deteriorates. At the same time, KI is prone to moisture absorption and clumping, which will cause uneven distribution of the flux core components, further reduce arc stability, and ultimately aggravate welding spatter. (3) The core structure is simple and the functional components cannot act precisely: Traditional cores adopt a single structure of "uniformly mixed components". The deoxidizer will be consumed prematurely in the high-temperature arc zone, resulting in insufficient deoxidation reaction in the core area of ​​the molten pool and easy generation of CO; the slag-forming agent will decompose prematurely at high temperature in the arc zone, resulting in low slag coverage and easy intrusion of external oxygen into the molten pool, further promoting CO generation. (4) The weld grains are coarse and the resistance to gas impact is weak: The lack of efficient nucleation cores in the weld pool leads to larger grain size and lower density of the deposited metal. The grain boundaries are easy to become channels for CO to escape, which will aggravate spatter and reduce the mechanical properties of the weld.

[0004] Chinese Patent 202510640053.8 discloses a wear-resistant flux-cored welding wire and its manufacturing method (application date: May 19, 2025). The welding wire consists of a low-carbon steel strip wrapped with three layers of flux: the inner main wear-resistant layer contains chromium carbide, recycled slag, cobalt-based alloy, and nanofibers; the gradient mixing layer is a gradient transition between the inner and outer layers; and the outer auxiliary wear-resistant layer contains tungsten carbide, ferrovanadium alloy, and electrolytic manganese powder. The preparation method includes waste slag recycling, ultrasonic dispersion mixing, layered vibration compaction, and cold drawing. This invention improves wear resistance by 20%~30% and reduces costs by 15%~20% through the synergistic effect of the three-layer structure, nano-reinforcement, and solid waste recycling. However, this patent has the following defects: the multi-layer flux-cored structure in the solution only focuses on the physical isolation and gradient transition of wear-resistant components, which is essentially a simple stacking of multiple functional materials. It does not perform functional design based on the significant temperature gradient and reaction time differences between the arc zone, the surface of the molten pool, and the core zone of the molten pool during welding metallurgy. The simultaneous melting and mixing of the various flux core layers during welding leads to a disordered temporal and spatial sequence of reactions among key functional components such as arc stabilization, slag formation, and deoxidation, making it impossible to achieve the synergistic effect of "first stabilizing the arc and isolating oxygen, then deeply deoxidizing." Therefore, although this structure improves wear resistance, it is difficult to systematically solve the core problems of high welding spatter rate and numerous weld defects caused by the uncontrolled escape of CO gas.

[0005] The fundamental flaw in existing technologies lies in their inability to adapt to the temperature gradient changes and corresponding reaction requirements from the arc zone to the core of the molten pool during welding. They are limited to adjusting component ratios or optimizing mixing processes, failing to address the core need of "achieving functional specialization through structural innovation." Therefore, developing a flux-cored welding wire that synergistically suppresses CO generation and reduces spatter through structural innovation is a pressing technical problem that researchers in this field need to solve. Summary of the Invention

[0006] The purpose of this invention is to provide a layered structure low-spatter flux-cored welding wire and its preparation method, which specifically solves the problems of existing flux-cored welding wires, such as the lack of continuous arc stabilizing agent effect, poor slag-forming agent effect, insufficient deoxidation in the core area of ​​the molten pool, and coarse weld grains, resulting in severe welding spatter and poor weld performance.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A layered low-spatter flux-cored welding wire includes a metal outer sheath 1 and a layered flux core filled within the metal outer sheath 1. The layered flux core consists of an outer flux core 2 and an inner flux core 3, with the inner flux core 3 filling the central area enclosed by the outer flux core 2. The core design of the outer flux core 2 is to address the problems of insufficient arc stabilizing agent effect, poor slag-forming agent effect, and insufficient auxiliary deoxidation in the prior art (corresponding to problems 2 and 3 in the background art). The design of the inner flux core 3 focuses on addressing the shortcomings of insufficient deoxidation in the core area of ​​the molten pool and coarse weld grains (corresponding to problems 1 and 4 in the background art). The dual-layer structure works together to achieve the functional division of "internal layer cuts off CO source and outer layer controls CO escape".

[0008] The outer flux core 2 is located on the inner surface of the metal outer sheath 1, and has a thickness of 0.15~0.25mm; based on the total mass of the layered low-spatter flux-cored wire as 100%, the mass of the outer flux core 2 accounts for 8%~12% of the total mass of the flux-cored wire; Based on the total mass of the outer core 2 as 100%, it comprises: 3%~5% of mesoporous SiO2-KI composite with a particle size of 1~5μm, 8%~12% of composite slagging agent, 10%~15% of Fe-Mn alloy powder, and the balance being reduced iron powder with a particle size of 5~10μm. Based on the total mass of the layered low-splash flux-cored wire, the inner flux core 3 accounts for 10% to 18% of the total mass of the flux-cored wire. Based on the total mass of the inner flux core 3, it comprises: 8% to 12% TiC@ZrB2 core-shell particles with a particle size of 2 to 5 μm, 6% to 9% Fe-Sc-Ti alloy powder, 4% to 6% aluminum powder, and the balance being reduced iron powder with a particle size of 5 to 10 μm. The combined mass of the outer and inner flux cores accounts for 18% to 26% of the total mass of the flux-cored wire (including the metal sheath 1); The mesoporous SiO2-KI composite is a structure in which KI crystals are supported in mesoporous SiO2 channels with a pore size of 20~30nm, and the KI loading is 30%~40%. The KI loading refers to the mass percentage of KI in the mesoporous SiO2-KI composite.

[0009] The composite slag-forming agent is a composite particle formed by high-temperature sintering and crushing of CaF2, MgO and La2O3 in a mass ratio of 5:3:1. The particle size of CaF2, MgO and La2O3 is 5~10μm, and the particle size of the composite slag-forming agent is 40~60μm.

[0010] The metal outer skin 1 is made of cold-rolled low-carbon steel strip.

[0011] The diameter of the flux-cored welding wire is 2.0~6.0mm.

[0012] Based on the total mass of the Fe-Mn alloy powder as 100%, it contains: 14%~18% Mn, with the balance being Fe, and the particle size of the Fe-Mn alloy powder is 20~30μm.

[0013] Based on a total mass of 100%, the Fe-Sc-Ti alloy powder contains: 0.6%~1.0% Sc, 16%~20% Ti, with the balance being Fe; the particle size of the Fe-Sc-Ti alloy powder is 20~30μm.

[0014] The outer metal sheath 1 is made of cold-rolled low-carbon steel strip, and the grade of cold-rolled low-carbon steel strip selected is DC07 in GB / T 5213. This grade of steel strip has good ductility and rolling performance, which can ensure that it is not easy to crack during subsequent flux filling and drawing process, and ensure the quality of welding wire forming.

[0015] Outer core 2 includes: ① Mesoporous SiO2-KI composite with a particle size of 1~5μm (mesoporous pore size 20~30nm): Its core function is to achieve high-temperature sustained release of arc stabilizer KI, solving the problems of easy volatility and unsustainable effect of traditional KI; ② Composite slag-forming agent: used to form a dense slag film on the surface of the molten pool, preventing external oxygen intrusion and solving the problems of easy decomposition and low coverage of traditional slag-forming agents; ③Fe-Mn alloy powder: It can assist in deoxidation in the arc zone and the surface of the molten pool, and form a "two-stage deoxidation system" in combination with the strong deoxidation in the inner layer, thereby reducing the overall oxygen content of the molten pool; ④ The remainder is reduced iron powder: with a particle size of 5~10μm, grade FHT100・25 in YB / T5138, as a basic filler component to ensure the weldability of the welding wire.

[0016] Taking the total mass of the layered low-splash flux-cored wire as 100%, the outer flux-cored layer 2 accounts for 8%~12% of the mass. This range is set based on "functional effectiveness + process feasibility": if the proportion is less than 8%, the total amount of mesoporous SiO2-KI composite is insufficient, and K cannot be continuously released. + Ions maintain arc stability, but the slag film generated by the composite slag-forming agent is not thick enough and has poor density, leading to increased external oxygen intrusion and aggravated CO generation. If the proportion is higher than 12%, it will squeeze the inner core filling space, resulting in insufficient strong deoxidation components and inadequate deoxidation in the core area of ​​the molten pool, thus failing to inhibit CO generation from the source.

[0017] The inner core contains: ①TiC@ZrB2 core-shell particles with a particle size of 2~5μm: They have the functions of relay deoxidation and grain refinement, solving the problems of premature consumption of traditional deoxidizers and coarse grains in welds; ②Fe-Sc-Ti alloy powder: a strong deoxidizing core component. Sc can activate the deoxidizing activity of Ti, greatly improving the deoxidation efficiency and solving the problem of low deoxidation efficiency of traditional Fe-Ti alloy powder; ③ Aluminum powder: an auxiliary deoxidizing component that further reduces the oxygen content in the core area of ​​the molten pool; ④ The remainder is reduced iron powder: consistent with the reduced iron powder used in the outer core, ensuring the consistency of the core composition and welding stability.

[0018] Taking the total mass of the layered low-splash flux-cored wire as 100%, the mass ratio of the inner flux core 3 is 10%~18%. The reason for setting this range is as follows: If the ratio is less than 10%, the content of strong deoxidizing components (Ti, Sc, Zr) and grain refining components (TiC) is insufficient, which cannot preferentially combine with dissolved oxygen in the core area of ​​the molten pool, and it is difficult to refine the weld grain, resulting in high CO content and decreased weld tensile strength; if the ratio is higher than 18%, the total ratio of the outer and inner flux cores will exceed the upper limit of 26%, which will make the metal skin prone to cracking and deformation during rolling and drawing, and the flux core components are prone to segregation, affecting the stability of welding performance.

[0019] The combined mass of the outer and inner core fluxes accounts for 18% to 26% of the total mass of the flux-cored wire.

[0020] Design details of key composite components: 1) Mesoporous SiO2-KI composite: This structure consists of KI crystals loaded within mesoporous SiO2 channels with a pore size of 20-30 nm, with a KI loading of 30%-40%. This composite represents a cross-disciplinary technological innovation, addressing the problem of one-time volatilization of traditional KI at high welding temperatures through the high-temperature structural stability of mesoporous SiO2. The application environment requirements for the mesoporous SiO2 carrier in this invention differ fundamentally from existing technologies: the core requirement for existing mesoporous carriers in the field of drug sustained release is slow release at room / low temperatures, while this invention needs to solve the dual technical challenges of "carrier structural stability at high temperatures (3000-6000K)" and "matching the release rate of the active component (KI) to the welding cycle." To achieve the aforementioned structural stability and controllable release at high temperatures, this invention innovates key parameters of the mesoporous carrier: adjusting the large-pore (50-100 nm) mesoporous SiO2 commonly used in drug sustained release to a small-pore structure of 20-30 nm suitable for the high-temperature welding environment. Reducing the pore size significantly increases the specific surface area and pore wall thickness of the mesoporous structure, enabling it to effectively maintain the integrity of the pore framework and prevent premature collapse under the instantaneous high-temperature impact of an electric arc at 3000~6000K during the 70℃ drying process. Simultaneously, the smaller pore size provides a stronger confinement effect on KI crystals, achieving a slow-release kinetics matched to the welding speed (300mm / min), ensuring the K... +A continuous and stable supply of ions throughout the entire welding cycle. By controlling the pore size and pore density of mesoporous SiO2, its structural integrity is maintained during the 70℃ drying process and under the high temperature of the electric arc, thus achieving the slow release of KI and matching the needs of the entire welding process; 2) Preparation of mesoporous SiO2: P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) was used as a template agent, and tetraethyl orthosilicate was used as the silicon source. The mixture was stirred at 40℃ for 24 h, aged at 80℃ for 12 h, and calcined at 550℃ for 6 h to remove the template agent, resulting in mesoporous SiO2 with a pore size of 20~30 nm. This preparation process can ensure that the mesoporous structure remains intact during the drying process at 70℃ and the high temperature of 3000~6000K arc, achieving a slow release of KI and matching the welding speed (300 mm / min). 3) Composite slagging agent: This composite particle is formed by sintering CaF2, MgO, and La2O3 in a 5:3:1 mass ratio at 1250℃ followed by crushing. This design solves the problems of segregation and melting point mismatch in traditional mechanically mixed slagging agents. ①Sintering synergistic effect: The high temperature of 1250℃ enables the three components to form stable composite particles, avoiding premature decomposition at high temperature; ② Precisely matched ratio: The 5:3:1 ratio matches the melting point and viscosity of the slag-forming agent with the surface temperature of the molten pool (1800~2000K), ensuring rapid melting to form slag and avoiding excessively thin slag loss or excessively thick slag uneven coverage; ③ Component synergistic optimization: CaF2 adjusts the viscosity of the slag and improves its fluidity, MgO enhances the density of the slag and strengthens the oxygen barrier effect, and La2O3 refines the slag particles and improves its spreadability. The three work together to form a "fusible, dense and uniform" slag film. 4) Fe-Mn alloy powder: Based on 100% of total mass, it contains 14%~18% Mn and the balance is Fe, with a particle size of 20~30μm; This composition design can ensure that Mn can efficiently assist in deoxidation in the arc zone, and the generated MnO can easily be incorporated into the slag, avoiding the formation of inclusions; 5) Fe-Sc-Ti alloy powder: Based on a total mass of 100%, it contains 0.6%~1.0% Sc, 16%~20% Ti, and the balance is Fe, with a particle size of 20~30μm; Sc breaks through the oxidation barrier of Ti by preferentially deoxidizing, enhances the oxygen affinity of Ti by electron transfer, and accelerates the diffusion of Ti by lattice distortion, which significantly reduces the activation energy of Ti deoxidation reaction, making the deoxidation efficiency much higher than that of traditional Fe-Ti alloy powder; 6) TiC@ZrB2 core-shell particles: Prepared by the following method: TiC with a particle size of 1~3μm and ZrB2 micro powder with a particle size of 80~150nm are mixed at a mass ratio of 1:1.5~1:2, and ball-milled for 1~1.5h under argon protection (ball-to-material ratio 5:1, ball milling media is stainless steel balls, rotation speed 300r / min) to form a core-shell structure of ZrB2 coating TiC; the ZrB2 shell can protect TiC from initial arc oxidation, and the decomposition temperature of ZrB2 (2200℃) and TiC (1800℃) form a gradient, realizing "Zr deoxidation first (high temperature zone) → Ti The relay mechanism of "post-deoxidation (intermediate temperature zone)" has its core value in that the ZrB2 shell not only physically protects TiC from initial arc oxidation, but more importantly, it utilizes the fact that the decomposition temperature of ZrB2 (approximately 2200℃) is higher than that of TiC (approximately 1800℃) to form a natural deoxidation gradient, ensuring the continuity and efficiency of the deoxidation reaction. At the same time, TiC can act as a grain nucleation core, refining the weld grain.

[0021] The total filling rate of the outer core 2 and the inner core 3 is 18%~26%. This range can take into account both the functional effectiveness of the core and the forming processability of the welding wire, avoiding insufficient functional components due to too low a filling rate, or cracking of the metal outer skin due to too high a filling rate.

[0022] The preparation method of this layered low-spatter flux-cored welding wire includes the following steps, each designed to ensure the structural integrity and compositional uniformity of the layered flux core: S1: Core preparation 1) Preparation of outer core paste: Mesoporous SiO2-KI composite, composite slag-forming agent, Fe-Mn alloy powder, and reduced iron powder are mixed in proportion, and 10%~15% of water-soluble binder (2%~4% PVA aqueous solution, PVA molecular weight 8000~10000) relative to the mass fraction of outer core 2 is added. Stirring forms a uniform paste with a viscosity of 5000~8000 mPa·s. This viscosity ensures that the paste adheres uniformly to the inner wall of the U-shaped groove during the subsequent roller coating process and is not easy to fall off after drying. 2) Preparation of inner core powder: TiC@ZrB2 core-shell particles, Fe-Sc-Ti alloy powder, aluminum powder and reduced iron powder are mixed evenly in proportion. No binder is needed to avoid affecting the reactivity of the inner core components in the core area of ​​the molten pool. S2: U-groove rolling: The metal outer skin 1 (DC07 cold-rolled low carbon steel strip) with a width of 3~5mm is rolled into a U-groove. The groove depth design needs to match the subsequent outer core coating thickness and inner core filling amount to ensure a compact layered core structure. S3: Outer core coating: The outer core paste prepared in step S1 is uniformly coated onto the inner surface of the U-shaped groove using a roller coating process; the roller coating process can ensure uniform paste thickness and avoid local over-thickness or under-thinness, which may lead to failure of the outer layer function; S4: Drying and shaping: Dry at 60~80℃ for 15~20min to form a solid paste layer of the outer core paste on the inner surface of the U-shaped groove; this drying temperature and time can ensure that the binder is fully cured, while avoiding premature volatilization of KI due to excessive temperature; S5: Inner core filling and forming: Inner core 3 is filled into the U-shaped groove formed in step S4. Vibration is used to make the inner core 3 compact (to avoid internal voids causing component segregation during welding). Then the U-shaped groove is rolled into a circle and drawn to a diameter of 2.0~6.0mm. The drawing diameter can be adjusted according to the actual welding requirements to ensure that the welding wire is suitable for different welding scenarios.

[0023] This invention addresses four major problems in the prior art through a synergistic design of "layered core structure + specialized composite components," achieving end-to-end control by "blocking the CO source in the inner layer and controlling CO escape in the outer layer." The specific mechanism is as follows: 1. Mechanism of action of outer core 2 (addressing issues of insufficient arc stabilization, oxygen intrusion, and assisted deoxygenation): 1) Stabilizes the electric arc and suppresses spatter-inducing factors: The mesoporous SiO2-KI composite slowly releases K+ under the high temperature of the electric arc. + Ions continuously maintain the conductivity of the electric arc, avoiding the arc energy fluctuations caused by the traditional KI's "excessive volatilization in the early stage and lack of arc-stabilizing components in the later stage"; a stable electric arc can ensure smooth droplet transition and reduce spatter caused by the deterioration of droplet transition. 2) Formation of protective slag to isolate external oxygen: The composite slag-forming agent melts rapidly on the surface of the molten pool to form a continuous and dense slag film, blocking the intrusion of oxygen in the air into the molten pool and reducing the indirect path of "external oxygen → CO reaction → CO generation"; at the same time, the slag film can also buffer the impact force when CO escapes, reducing the probability of molten metal being entrained. 3) Assisted deoxidation to reduce oxygen content in the molten pool: Mn in Fe-Mn alloy powder preferentially combines with oxygen in the arc zone and on the surface of the molten pool to form MnO (MnO is easily incorporated into the molten slag), thus achieving assisted deoxidation; this process can reduce the overall oxygen concentration in the molten pool, reduce the load on deoxidation of the inner core area, and form a synergistic effect of "two-stage deoxidation"; 2. Mechanism of action of inner core 3 (addressing issues of insufficient deoxidation and coarse grains in the core area): 1) Strong deoxidation, blocking the source of CO generation: Sc in Fe-Sc-Ti alloy powder activates the deoxidation activity of Ti, so that Ti, Sc, and Zr (from TiC@ZrB2 core-shell particles) preferentially combine with dissolved oxygen in the core area of ​​the molten pool to generate stable oxides such as Sc2O3, TiO2, and ZrO2 (these oxide particles are small and can be discharged with the slag); since the deoxidation capacity of Ti, Sc, and Zr is much higher than that of C, it can significantly inhibit the CO reaction and reduce CO generation from the source. In Fe-Sc-Ti alloy powder, Sc activates the deoxidation activity of Ti through a "triple synergistic effect," significantly reducing the activation energy of the Ti deoxidation reaction. The specific mechanisms are as follows: ① Preferential deoxidation breaking the barrier: Sc's deoxidation ability (standard formation free energy) is higher than Ti's, so it preferentially combines with dissolved oxygen in the core region of the molten pool to form Sc2O3, reducing the competitive resistance between Ti and oxygen and breaking the barrier of the TiO2 passivation film that is easily formed on the Ti surface; ② Electron transfer enhancing activity: The outer electronic structure of Sc atoms makes it easy to release electrons upon entering the molten pool, which are transferred to the 3d orbitals of Ti atoms, enhancing Ti's affinity for oxygen and accelerating the combination reaction between Ti and O in the molten pool; ③ Lattice distortion promoting diffusion: When Sc and Ti form a solid solution, the difference between the atomic radius of Sc (0.161 nm) and the atomic radius of Ti (0.145 nm) leads to lattice distortion, expanding the diffusion channels of Ti atoms in the molten pool, allowing Ti to reach the oxygen-rich region more quickly to undergo the deoxidation reaction. These three synergistic effects work together to significantly reduce the activation energy of the Ti deoxidation reaction, enabling it to quickly and efficiently capture dissolved oxygen in the core area of ​​the molten pool, thereby fundamentally inhibiting the CO reaction, effectively blocking the source of CO porosity, and refining the solidification structure. 2) Precise reaction, avoiding the side effects of deoxidizers: The inner core flux is concentrated in the core area with the flow of the molten pool during welding through the "center filling" structural design, avoiding the problem of traditional deoxidizers being consumed too early in the arc area; at the same time, Ti, Sc and other substances only react in the core area, reducing the risk of them forming coarse inclusions with N and S, improving the cleanliness of the molten pool, and further reducing the CO escape channels. 3) Grain refinement enhances resistance to gas impact: TiC in TiC@ZrB2 core-shell particles can serve as an efficient nucleation core for weld grains, refining the grains of the deposited metal; at the same time, Sc and Ti in Fe-Sc-Ti alloy powder can also improve weld density through solid solution strengthening; the refined grains and higher density can reduce the number of grain boundaries, reduce CO escape channels, enhance the weld's resistance to gas impact, and improve the weld's tensile strength. 3. Synergistic mechanism of bilayer drug core: 1) Precise spatial and temporal division of functional components: The outer core reacts rapidly in the high-temperature arc zone / molten pool surface (arc stabilization, oxygen isolation, and auxiliary deoxidation), while the inner core reacts slowly in the mid-temperature molten pool core zone (strong deoxidation and grain refinement), perfectly matching the "temperature gradient and reaction requirements of different regions" during welding. Specifically, there is a significant temperature gradient in the welding process: arc zone (3000~6000K) → molten pool surface (1800~2000K) → molten pool core zone (1500~1800K). The double-layer structure design of this invention is precisely to adapt to this gradient: the outer core reacts rapidly in the high-temperature zone (e.g., composite slag-forming agent forms a slag film, mesoporous SiO2 releases KI to stabilize the arc), while the inner core reacts slowly in the mid-temperature core zone (e.g., TiC@ZrB2 core-shell particles relay deoxidation). This precise matching of "structure-temperature-function" is the core prerequisite for achieving "cutting off the CO source in the inner layer and controlling CO escape in the outer layer", which solves the defect of "uniform mixing of all components and misalignment of action" in traditional single-core formulations. 2) CO control through internal and external linkage: The inner layer blocks the source of CO generation through "strong deoxygenation", while the outer layer reduces the raw materials for CO generation and inhibits CO escape through "oxygen isolation + arc stabilization", forming a full-chain control system from "CO generation" to "CO escape", minimizing CO-induced splashing. 3) Dual improvement in performance and process: Grain refinement and solid solution strengthening improve weld strength, toughness and wear resistance, while arc stability and reliable slag design improve welding process stability, achieving the dual goals of "low spatter" and "high performance".

[0024] Beneficial technical effects of the present invention: (1) Significant reduction in welding spatter: Through the dual-layer synergistic design of “inner layer blocking CO generation (through efficient deoxidation of Fe-Sc-Ti alloy powder) + outer layer inhibiting CO escape (through full-process arc stabilization achieved by mesoporous SiO2-KI composite),” the amount of welding spatter is reduced by more than 30% compared with traditional single flux-cored wire (such as E501T-1 in GB / T10045); the slow-release effect of mesoporous SiO2-KI composite stabilizes the arc throughout the process, further reducing spatter caused by the deterioration of droplet transition, effectively solving the core problem of severe spatter in the background technology; (2) Dual improvement in weld performance and defect control: The grain refinement effect of TiC@ZrB2 core-shell particles combined with the solid solution strengthening of Fe-Sc-Ti alloy powder increases the tensile strength of the deposited metal by more than 20% compared with traditional welding wire (up to 650 or more); the dense slag film of the composite slag-forming agent and the two-stage deoxidation system significantly reduce the occurrence rate of defects such as weld porosity and slag inclusion, and specifically improve the problems of poor weld performance and many defects in the background technology; (3) Improved stability of core components: The layered structure makes the functional components evenly distributed. The coating of KI by mesoporous SiO2 can prevent KI from absorbing moisture and clumping. The inner layer “center filling” design can prevent the premature consumption of deoxidizers such as Ti and Sc, thus solving the problems of easy segregation and poor stability of traditional core components. (4) The source of technical effect and creative support: The layered design of this invention transcends the existing physical stacking paradigm of multi-layer flux cores. Its essence lies in the deep integration of the "spatiotemporal functional division" based on the temperature gradient of the welding process and the "chemical reaction synergy" of the special composite components. It is this structural innovation that has become the fundamental guarantee for achieving the significant technical effects of (1) to (3) (compared to the traditional E501T-1, the amount of spatter is reduced by more than 30%, the tensile strength is increased by more than 20%, and the components are highly stable). This precise matching of "structure-function-component" makes the comprehensive effect of low spatter, high performance and high stability an inevitable result that existing technologies cannot achieve through conventional design methods, thereby strengthening the irreplaceability and application advantages of the technical solution from the root.

[0025] In summary, the significant beneficial effects of the layered low-spatter flux-cored wire provided by this invention stem from its unique technical solution. Specifically: ① Structurally, the radial spatiotemporal division of labor between the outer paste layer and the inner powder layer provides a foundation for the precise action of functional components; ② In terms of composition, a series of specialized composite components, such as mesoporous SiO2-KI composites and TiC@ZrB2 core-shell particles, are innovatively applied, achieving synergistic and enhanced functionality; ③ Ultimately, the invention achieves quantitative technical benefits of reducing spatter by more than 30% and increasing weld strength by more than 20%. This synergistic effect produced by the interaction of specific structures and specific components is something that cannot be readily apparent to those skilled in the art based on existing technologies. Attached Figure Description

[0026] Figure 1 The process flow for preparing the layered structure low-splash flux-cored wire of this invention is as follows; Figure 2 This is a cross-sectional view perpendicular to the length direction after the steel strip is rolled into a U-shaped groove and the outer layer of flux core paste is rolled onto its inner surface during the preparation of the layered low-splash flux-cored wire of the present invention. Figure 3 This is a cross-sectional view of the layered low-splash flux-cored wire of the present invention, perpendicular to its length. In the diagram: 1—metal outer sheath; 2—outer core; 3—inner core; 4—steel strip rolled into a U-shaped groove; 5—outer core paste coated on the inner surface of the U-shaped groove.

[0027] Caption: 5 is prepared into 2, and 4 is prepared into 1. Detailed Implementation

[0028] The principles and effects of the present invention are described below with reference to embodiments and comparative examples. The embodiments and comparative examples listed are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0029] Example 1

[0030] A layered low-splash flux-cored wire includes a metal sheath 1 and a layered flux core filled within the metal sheath 1. The layered flux core consists of an outer flux core 2 and an inner flux core 3, with the inner flux core 3 filling the central region enclosed by the outer flux core 2. Metal outer skin 1 is made of cold-rolled low-carbon steel strip; The outer flux core 2 is located on the inner surface of the metal outer sheath 1, and has a thickness of 0.2 mm; taking the total mass of the layered low-spatter flux-cored wire as 100%, the mass of the outer flux core 2 accounts for 10% of the total mass of the layered flux-cored wire. Based on the total mass of the outer core 2 as 100%, it contains: 4% mesoporous SiO2-KI composite with a particle size of 1~5μm, 10% composite slagging agent, 12.5% ​​Fe-Mn alloy powder, and the balance is reduced iron powder. The mesoporous SiO2-KI composite is a structure in which KI crystals are supported in mesoporous SiO2 channels with a pore size of 20~30nm, and the KI loading is 30%~40%. The composite slag-forming agent is a composite particle formed by high-temperature sintering and crushing of CaF2, MgO and La2O3 in a mass ratio of 5:3:1. The particle size of CaF2, MgO and La2O3 is 5~10μm, and the particle size of the composite slag-forming agent is 40~60μm. Based on the total mass of Fe-Mn alloy powder as 100%, it contains: 14%~18% Mn, with the balance being Fe; the particle size of Fe-Mn alloy powder is 20~30μm; Taking the total mass of the layered low-splash flux-cored wire as 100%, the inner flux core 3 accounts for 14% of the total mass of the layered flux-cored wire. Taking the total mass of the inner flux core 3 as 100%, it contains: 10% TiC@ZrB2 core-shell particles with a particle size of 2~5μm, 7.5% Fe-Sc-Ti alloy powder, 5% aluminum powder, and the balance is reduced iron powder. Based on a total mass of 100% in the Fe-Sc-Ti alloy powder, it contains: 0.8% Sc, 18% Ti, and the balance is Fe, with a mass ratio of Sc to Ti of 1:24; the particle size of the Fe-Sc-Ti alloy powder is 20~30μm; The particle size of the reduced iron powder is 5~10μm.

[0031] The preparation method of layered low-splash flux-cored welding wire includes the following steps (see appendix). Figure 1 ): S1: Mix the mesoporous SiO2-KI composite, composite slag-forming agent, Fe-Mn alloy powder, and reduced iron powder, add a water-soluble binder at a mass fraction of 12.5% ​​relative to the outer core 2, and stir to form a uniform paste with a viscosity of 6500 mPa·s. The water-soluble binder is a 3% PVA aqueous solution with a molecular weight of 8000~10000. Mix the inner core powder evenly. S2: Roll a 4mm wide cold-rolled low-carbon steel strip into a U-shaped groove; S3: The outer core paste prepared in step S1 is uniformly coated onto the inner surface of the U-shaped groove prepared in step S2 using a roller coating process. S4: Dry at 60~80℃ for 17.5 min to form a solid paste layer on the inner surface of the U-shaped groove (see attached). Figure 2 ); S5: Fill the U-shaped groove formed in step S4 with the inner core 3, and compact the inner core 3 by vibration. Then roll the U-shaped groove into a circle (see appendix). Figure 3 ), drawn to a diameter of 4.0 mm.

[0032] Mesoporous SiO2-KI composite was prepared by impregnation-drying method: mesoporous SiO2 was immersed in saturated KI aqueous solution, left to stand for 2.5 h, and then dried at 70 °C until KI crystals were loaded in the mesoporous channels; The composite slag-forming agent is prepared by sintering CaF2, MgO, and La2O3 particles with a particle size of 5-10 μm at 1250℃ and then crushing them into particles with a particle size of 40-60 μm. The preparation method of TiC@ZrB2 core-shell particles is as follows: P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) is used as a template agent, and tetraethyl orthosilicate is used as a silicon source. The mixture is stirred at 40℃ for 24 h, aged at 80℃ for 12 h, and calcined at 550℃ for 6 h to remove the template agent, yielding mesoporous SiO2 with a pore size of 20-30 nm. TiC with a particle size of 1-3 μm and ZrB2 micropowder with a particle size of 80-150 nm are mixed at a mass ratio of 1:1.75 and ball-milled for 1.25 h under argon protection at a ball-to-material ratio of 5:1 and a rotation speed of 300 r / min to form a ZrB2-coated TiC core-shell structure.

[0033] Example 2

[0034] A layered low-splash flux-cored wire includes a metal sheath 1 and a layered flux core filled within the metal sheath 1. The layered flux core consists of an outer flux core 2 and an inner flux core 3, with the inner flux core 3 filling the central region enclosed by the outer flux core 2. Metal outer skin 1 is made of cold-rolled low-carbon steel strip; The outer flux core 2 is located on the inner surface of the metal outer sheath 1, and has a thickness of 0.15 mm; taking the total mass of the layered low-splash flux-cored wire as 100%, the mass of the outer flux core 2 accounts for 8% of the total mass of the layered flux-cored wire. Based on the total mass of the outer core 2 as 100%, it contains: 3% of mesoporous SiO2-KI composite with a particle size of 1~5μm, 8% of composite slagging agent, 10% of Fe-Mn alloy powder, and the balance is reduced iron powder. The mesoporous SiO2-KI composite is a structure in which KI crystals are supported in mesoporous SiO2 channels with a pore size of 20~30nm, and the KI loading is 30%~40%. The composite slag-forming agent is a composite particle formed by high-temperature sintering and crushing of CaF2, MgO and La2O3 in a mass ratio of 5:3:1. The particle size of CaF2, MgO and La2O3 is 5~10μm, and the particle size of the composite slag-forming agent is 40~60μm. Based on the total mass of Fe-Mn alloy powder as 100%, it contains: 14%~18% Mn, with the balance being Fe; the particle size of Fe-Mn alloy powder is 20~30μm; Taking the total mass of the layered low-splash flux-cored wire as 100%, the inner flux-cored wire 3 accounts for 14% of the total mass of the layered flux-cored wire. Taking the total mass of the inner flux-cored wire 3 as 100%, it contains: 8% TiC@ZrB2 core-shell particles with a particle size of 2~5μm, 6% Fe-Sc-Ti alloy powder, 4% aluminum powder, and the balance is reduced iron powder. Based on a total mass of 100% in the Fe-Sc-Ti alloy powder, it contains: 0.6% Sc, 16% Ti, and the balance is Fe; the particle size of the Fe-Sc-Ti alloy powder is 20~30μm; The particle size of the reduced iron powder is 5~10μm.

[0035] A method for preparing a layered, low-splash flux-cored welding wire includes the following steps: S1: Mix the mesoporous SiO2-KI composite, composite slag-forming agent, Fe-Mn alloy powder, and reduced iron powder, add a water-soluble binder at a mass fraction of 10%~15% relative to the outer core 2, and stir to form a uniform paste with a viscosity of 5000 mPa·s. The water-soluble binder is a 2% PVA aqueous solution with a molecular weight of 8000~10000. Mix the inner core powder evenly. S2: Roll a 3mm wide cold-rolled low-carbon steel strip into a U-shaped groove; S3: The outer core paste prepared in step S1 is uniformly coated onto the inner surface of the U-shaped groove prepared in step S2 using a roller coating process. S4: Dry at 60~80℃ for 15 minutes to form a solid paste layer on the inner surface of the U-shaped groove; S5: Fill the U-shaped groove formed in step S4 with inner core 3, make the inner core 3 compact by vibration, and then roll the U-shaped groove into a circle and draw it to a diameter of 2.0 mm.

[0036] Mesoporous SiO2-KI composites were prepared by an impregnation-drying method: P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) was used as a template agent, and tetraethyl orthosilicate was used as the silicon source. The mixture was stirred at 40℃ for 24 h, aged at 80℃ for 12 h, and calcined at 550℃ for 6 h to remove the template agent, yielding mesoporous SiO2 with a pore size of 20-30 nm. The mesoporous SiO2 was then immersed in a saturated KI aqueous solution, allowed to stand for 2 h, and then dried at 70℃ until KI crystals were loaded into the mesoporous channels. The composite slag-forming agent is prepared by sintering CaF2, MgO, and La2O3 particles with a particle size of 5-10 μm at 1250℃ and then crushing them into particles with a particle size of 40-60 μm. The preparation method of TiC@ZrB2 core-shell particles is as follows: TiC with a particle size of 1~3μm and ZrB2 micro powder with a particle size of 80~150nm are mixed at a mass ratio of 1:1.5, and ball-milled for 1h under argon protection with a ball-to-material ratio of 5:1 and a rotation speed of 300r / min to form a core-shell structure of ZrB2 coating TiC.

[0037] Example 3

[0038] A layered low-splash flux-cored wire includes a metal sheath 1 and a layered flux core filled within the metal sheath 1. The layered flux core consists of an outer flux core 2 and an inner flux core 3, with the inner flux core 3 filling the central region enclosed by the outer flux core 2. Metal outer skin 1 is made of cold-rolled low-carbon steel strip; The outer flux core 2 is located on the inner surface of the metal outer sheath 1, with a thickness of 0.25 mm; taking the total mass of the layered low-spatter flux-cored wire as 100%, the mass of the outer flux core 2 accounts for 12% of the total mass of the layered flux-cored wire. Based on the total mass of the outer core 2 (100%), it comprises: mesoporous SiO₂ particles with a particle size of 1~5 μm. 2- The composition consists of 5% KI complex, 12% composite slag-forming agent, 15% Fe-Mn alloy powder, and the balance being reduced iron powder. The mesoporous SiO2-KI composite is a structure in which KI crystals are supported in mesoporous SiO2 channels with a pore size of 20~30nm, and the KI loading is 30%~40%. The composite slag-forming agent is a composite particle formed by high-temperature sintering of CaF2, MgO and La2O3 in a mass ratio of 5:3:1. The particle size of CaF2, MgO and La2O3 is 5~10μm, and the particle size of the composite slag-forming agent is 40~60μm. Based on the total mass of Fe-Mn alloy powder as 100%, it contains: 14%~18% Mn, with the balance being Fe; the particle size of Fe-Mn alloy powder is 20~30μm; Taking the total mass of the layered low-splash flux-cored wire as 100%, the inner flux-cored wire 3 accounts for 14% of the total mass of the layered flux-cored wire. Taking the total mass of the inner flux-cored wire 3 as 100%, it contains: 12% TiC@ZrB2 core-shell particles with a particle size of 2~5μm, 9% Fe-Sc-Ti alloy powder, 6% aluminum powder, and the balance is reduced iron powder. Based on a total mass of 100% in the Fe-Sc-Ti alloy powder, it contains: Sc 1.0%, Ti 20%, with the balance being Fe; the particle size of the Fe-Sc-Ti alloy powder is 20~30μm; The particle size of the reduced iron powder is 5~10μm.

[0039] A method for preparing a layered, low-splash flux-cored welding wire includes the following steps: S1: Mix the mesoporous SiO2-KI composite, composite slag-forming agent, Fe-Mn alloy powder, and reduced iron powder, add 15% (by mass) of water-soluble binder relative to the outer core 2, and stir to form a uniform paste with a viscosity of 8000 mPa·s. The water-soluble binder is a 4% PVA aqueous solution with a molecular weight of 8000~10000. Mix the inner core powder evenly. S2: Roll a 5mm wide cold-rolled low-carbon steel strip into a U-shaped groove; S3: The outer core paste prepared in step S1 is uniformly coated onto the inner surface of the U-shaped groove prepared in step S2 using a roller coating process. S4: Dry at 60~80℃ for 20 minutes to form a solid paste layer on the inner surface of the U-shaped groove; S5: Fill the U-shaped groove formed in step S4 with inner core 3, make the inner core 3 compact by vibration, and then roll the U-shaped groove into a circle and draw it to a diameter of 6.0 mm.

[0040] Mesoporous SiO2-KI composites were prepared by an impregnation-drying method: P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) was used as a template agent, and tetraethyl orthosilicate was used as the silicon source. The mixture was stirred at 40℃ for 24 h, aged at 80℃ for 12 h, and calcined at 550℃ for 6 h to remove the template agent, yielding mesoporous SiO2 with a pore size of 20-30 nm. The mesoporous SiO2 was then immersed in a saturated KI aqueous solution, allowed to stand for 3 h, and then dried at 70℃ until KI crystals were loaded into the mesoporous channels. The composite slag-forming agent is prepared by sintering CaF2, MgO, and La2O3 particles with a particle size of 5-10 μm at 1250℃ and then crushing them into particles with a particle size of 40-60 μm. The preparation method of TiC@ZrB2 core-shell particles is as follows: TiC with a particle size of 1~3μm and ZrB2 micro powder with a particle size of 80~150nm are mixed at a mass ratio of 1:2, and ball-milled for 1.5h under argon protection with a ball-to-material ratio of 5:1 and a rotation speed of 300r / min to form a core-shell structure of ZrB2 coated with TiC.

[0041] To verify the necessity of the layered structure and dedicated composite components of this invention, the following comparative examples were set up (except for the differences in labeling, the other parameters are the same as in Example 1): Comparative Example 1: Only the inner core 3 is retained, and the outer core 2 is removed. Everything else is the same as in Example 1.

[0042] Comparative Example 2: Only the outer core 2 is retained, and the inner core 3 is removed. Everything else is the same as in Example 1.

[0043] Comparative Example 3: The outer core 2 and the inner core 3 were mixed into a single core, which was then loaded into a U-shaped groove and pulled out. The rest was the same as in Example 1.

[0044] Comparative Example 4: The mesoporous SiO2-KI composite was replaced with a mechanical mixture of SiO2 and KI, and everything else was the same as in Example 1.

[0045] Comparative Example 5: The sintering composite slag-forming agent was replaced by a mechanical mixture of CaF2, MgO, and La2O3, and everything else was the same as in Example 1.

[0046] Comparative Example 6: The mass ratio of CaF2:MgO:La2O3 in the composite slag-forming agent was changed to 3:5:2, and the rest was the same as in Example 1.

[0047] Comparative Example 7: Fe-Ti alloy powder was used instead of Fe-Sc-Ti alloy powder, and everything else was the same as in Example 1.

[0048] Comparative Example 8: TiC@ZrB2 core-shell particles were replaced with a mechanical mixture of TiC and ZrB2, otherwise the same as in Example 1.

[0049] Comparative Example 9: The outer flux core accounts for 6% of the total mass of the welding wire, the inner flux core accounts for 14% of the total mass of the welding wire, and the rest is the same as in Example 1.

[0050] Comparative Example 10: The outer flux core accounts for 14% of the total mass of the welding wire, the inner flux core accounts for 14% of the total mass of the welding wire, and the rest is the same as in Example 1.

[0051] Comparative Example 11: The outer flux core accounts for 10% of the total mass of the welding wire, the inner flux core accounts for 8% of the total mass of the welding wire, and the rest is the same as in Example 1.

[0052] Comparative Example 12: The outer flux core accounts for 10% of the total mass of the welding wire, the inner flux core accounts for 20% of the total mass of the welding wire, and the rest is the same as in Example 1.

[0053] Comparative Example 13: The outer flux core accounts for 7% of the total mass of the welding wire, the inner flux core accounts for 9% of the total mass of the welding wire, and the rest is the same as in Example 1.

[0054] Comparative Example 14: Commercially available E501T-1 flux-cored welding wire was used.

[0055] Performance testing and results analysis 1. Detection Method

[0056] Welding spatter detection: According to section 3.2.4 "Spatter rate" of GB / T 25776—2010 "Methods for Evaluation of Welding Material Welding Process Performance" (although this standard tests the spatter rate of welding rods, the spatter rate test of flux-cored welding wire can be referred to); a gas shielded welding machine (welding current 200~220A, welding voltage 28~32V, welding speed 300mm / min, shielding gas is CO2) was used to collect spatter from a 100mm weld length and calculate the spatter reduction ratio (based on the same diameter E501T-1 welding wire, its spatter amount is 9g / 100mm).

[0057] Weld tensile strength test: According to GB / T 2651—2023 "Destructive Test of Welds of Metallic Materials - Transverse Tensile Test", standard tensile specimens (gauge length 50mm, diameter 10mm) were cut from the Q345 steel welded test plate (thickness 12mm), and the tensile strength was determined by a universal testing machine (loading rate 2mm / min). The average value of 3 specimens was taken.

[0058] Weld defect detection: Visual inspection is used to observe the porosity and slag inclusions on the weld surface and cross-section.

[0059] 2. Test Results

[0060] The test results are shown in Table 1:

[0061] 3. Results Analysis

[0062] Examples 1-3 verify the effectiveness of the technical solution: The spatter reduction rate of Examples 1-3 reached 30%~38%, the tensile strength of the weld reached 650~702MPa, and the defects were minimal, proving that the "double-layer flux core structure + special composite component" can effectively solve the four major problems in the background technology: the outer flux core solves the problems of arc stabilization and oxygen isolation, and the inner flux core solves the problems of core area deoxidation and grain coarsening, thus synergistically achieving low spatter and high performance.

[0063] Comparative Examples 1-3 verify the necessity of the layered structure: Comparative Example 1 (inner layer only), Comparative Example 2 (outer layer only), and Comparative Example 3 (mixed core) showed a splash reduction of only 8%~12% and an intensity of only 510~542 MPa, indicating numerous defects. The reasons are: a single inner layer cannot stabilize the arc or isolate oxygen; a single outer layer cannot deoxidize the core area; and the mixed structure disrupts the functional division of labor, failing to solve the problems in the background technology. This proves that the layered structure is the core guarantee of the technical effect. In particular, Comparative Example 3, even using the exact same chemical composition, disrupted the radial spatiotemporal structure of the "outer layer-inner layer," causing the reaction sequence and spatial distribution of its functional components to be disrupted. This leads to premature consumption of the arc stabilizer, waste of the deoxidizer on the surface, and poor slagging agent effect, ultimately resulting in a sharp decline in all performance aspects. This conversely confirms that the "structure" of this invention is as important as the "components," and both are indispensable and work synergistically.

[0064] Comparative Examples 4-8 verify the necessity of the special components: Comparative Example 4 (without mesoporous SiO2-KI) suffers from insufficient arc stabilization due to rapid KI volatilization; Comparative Examples 5-6 (without sintering slag-forming agent / proportion deviation) suffer from excessive oxygen intrusion due to poor slag film; Comparative Example 7 (without Fe-Sc-Ti) suffers from excessive CO generation due to low deoxidation efficiency; and Comparative Example 8 (without core-shell particles) suffers from poor grain refinement due to easy oxidation of TiC. The performance of these comparative examples is significantly inferior to that of the examples, proving that the special composite components are the key to solving the problems in the background technology.

[0065] The range of 8%~12% for the outer core, 10%~18% for the inner core, and 18%~26% for the total filler content in Comparative Examples 9-13 represents the optimal range that balances "functional effectiveness (low spatter, high performance)" and "process feasibility (wire forming, drawing stability)." When the proportion is below the lower limit or above the upper limit, problems such as a significant increase in spatter, a decrease in weld strength, and an increase in defects will occur, further supporting the scientific validity and rationality of the content range setting in the claims.

[0066] Comparative Example 14 uses the commonly available E501T-1 flux-cored welding wire.

[0067] In summary, this invention, through the "synergistic design of layered flux-cored structure and specialized composite components," specifically addresses the core technical pain points of existing flux-cored welding wires, demonstrating significant technical effectiveness and possessing both innovation and practicality. The scope of this invention must be determined based on the claims; all equivalent changes or modifications made based on the spirit and essence of this invention should be included within its protection scope.

Claims

1. A layered structure low-splash flux-cored welding wire, characterized in that, It includes a metal outer skin (1) and a layered drug core filled in the metal outer skin (1). The layered drug core consists of an outer drug core (2) and an inner drug core (3). The inner drug core (3) fills the central area enclosed by the outer drug core (2). The outer core (2) is located on the inner surface of the metal outer skin (1) and has a thickness of 0.15~0.25mm; based on the total mass of the layered low-splash flux-cored wire as 100%, the mass of the outer core (2) accounts for 8%~12% of the total mass of the flux-cored wire; Based on the total mass of the outer core (2) as 100%, it contains: 3%~5% of mesoporous SiO2-KI composite with a particle size of 1~5μm, 8%~12% of composite slag-forming agent, 10%~15% of Fe-Mn alloy powder, and the remainder is reduced iron powder with a particle size of 5~10μm. Based on the total mass of the layered low-splash flux-cored wire, the inner flux core (3) accounts for 10% to 18% of the total mass of the flux-cored wire. Based on the total mass of the inner flux core (3), it contains: 8% to 12% TiC@ZrB2 core-shell particles with a particle size of 2 to 5 μm, 6% to 9% Fe-Sc-Ti alloy powder, 4% to 6% aluminum powder, and the remainder is reduced iron powder with a particle size of 5 to 10 μm. The combined mass of the outer and inner flux cores accounts for 18% to 26% of the total mass of the flux-cored welding wire. The mesoporous SiO2-KI composite is a structure in which KI crystals are supported in mesoporous SiO2 channels with a pore size of 20~30nm, and the KI loading is 30%~40%.

2. The layered low-splash flux-cored wire according to claim 1, characterized in that, The composite slag-forming agent is a composite particle formed by high-temperature sintering and crushing of CaF2, MgO and La2O3 in a mass ratio of 5:3:

1. The particle size of CaF2, MgO and La2O3 is 5~10μm, and the particle size of the composite slag-forming agent is 40~60μm.

3. The layered low-splash flux-cored wire according to claim 1, characterized in that, The metal outer skin (1) is made of cold-rolled low-carbon steel strip.

4. The layered low-splash flux-cored wire according to claim 1, characterized in that, The diameter of the flux-cored welding wire is 2.0~6.0mm.

5. The layered low-splash flux-cored wire according to claim 1, characterized in that, Based on the total mass of the Fe-Mn alloy powder as 100%, it contains: 14%~18% Mn, with the balance being Fe, and the particle size of the Fe-Mn alloy powder is 20~30μm.

6. The layered low-splash flux-cored wire according to claim 1, characterized in that, Based on a total mass of 100%, the Fe-Sc-Ti alloy powder contains: 0.6%~1.0% Sc, 16%~20% Ti, with the balance being Fe; the particle size of the Fe-Sc-Ti alloy powder is 20~30μm.

7. A method for preparing a layered, low-splash flux-cored welding wire according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Mix the mesoporous SiO2-KI composite, composite slag-forming agent, Fe-Mn alloy powder, and reduced iron powder, and add a water-soluble binder with a mass fraction of 10%~15% relative to the outer core (2), and stir to form a uniform paste with a viscosity of 5000~8000 mPa·s. The water-soluble binder is a PVA aqueous solution with a mass fraction of 2%~4% and a molecular weight of 8000~10000. Mix the inner core powder evenly. S2: Cold-rolled low-carbon steel strip with a width of 3~5mm is rolled into a U-shaped groove; S3: The outer core paste prepared in step S1 is uniformly coated onto the inner surface of the U-shaped groove prepared in step S2 using a roller coating process. S4: Dry at 60~80℃ for 15~20min to form a solid paste layer on the inner surface of the U-shaped groove; S5: Fill the U-shaped groove formed in step S4 with inner core (3), and make the inner core (3) compact by vibration. Then roll the U-shaped groove into a circle and draw it to a diameter of 2.0~6.0mm.

8. The preparation method according to claim 7, characterized in that: The mesoporous SiO2-KI composite was prepared by an impregnation-drying method: mesoporous SiO2 was immersed in a saturated KI aqueous solution, left to stand for 2-3 hours, and then dried at 70°C until KI crystals were loaded into the mesoporous channels.

9. The preparation method according to claim 7, characterized in that: The composite slag-forming agent is prepared by sintering CaF2, MgO, and La2O3 particles with a particle size of 5-10 μm at 1250℃ and then pulverizing them into particles with a particle size of 40-60 μm.

10. The preparation method according to claim 7, characterized in that: The TiC@ZrB2 core-shell particles are prepared by mixing TiC with a particle size of 1~3μm and ZrB2 micro powder with a particle size of 80~150nm at a mass ratio of 1:1.5~1:2, ball milling for 1~1.5h under argon protection, with a ball-to-material ratio of 5:1 and a rotation speed of 300r / min to form a core-shell structure of ZrB2 coating TiC.

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