Low-alloy high-strength steel powder core wire for electric arc additive manufacturing and preparation method of low-alloy high-strength steel powder core wire

Abstract

The invention discloses a low-alloy high-strength steel powder core wire for electric arc additive manufacturing and a preparation method, the low-alloy high-strength steel powder core wire is composed of flux core powder and a carbon steel strip, the flux core powder comprises alloy components and slag system components, and the alloy components comprise, by mass, 1.5-3.0 wt% of ferrosilicon powder, 3.5-5.0 wt% of electrolytic manganese, 1.5-3.0 wt% of chromium powder, 7.5-9.5 wt% of nickel powder, 6.5-9.0 wt% of ferromolybdenum powder, smaller than or equal to 1.2 wt% of ferrovanadium powder and the balance slag system components. The balance is iron powder and inevitable impurities; when the wire is used for electric arc additive manufacturing, the accumulation body is excellent in strength and plasticity, the transverse and longitudinal tensile strength is not lower than 850 MPa, the yield strength is not lower than 540 MPa, the ductility is not lower than 14%, and the transverse and longitudinal anisotropy rate is lower.

Description

Technical Field

[0001] This invention relates to the field of materials for arc additive manufacturing, and more particularly to a low-alloy high-strength steel powder core wire for arc additive manufacturing and its preparation method. Background Technology

[0002] Low-alloy high-strength steel, with its excellent mechanical properties, weldability, and low cost, occupies an important position in shipbuilding, oil pipelines, heavy machinery, and bridge engineering. With industrial development, the demand for low-alloy high-strength steel components is gradually shifting towards larger, lighter, and more complex designs. However, traditional forging, casting, or machining methods are insufficient to meet the manufacturing requirements of large and complex low-alloy high-strength steel components, limiting the full realization of its high-performance application value.

[0003] In recent years, the rapid development of electric arc additive manufacturing technology has provided a new approach to solving this problem. This technology has successfully manufactured low-alloy high-strength steel components such as industrial valves, oil pipelines, large ship stern shaft supports, and nuclear power emergency pump pipelines, and has been put into practical engineering applications. Low-alloy high-strength steel electric arc additive manufacturing technology uses an electric arc as a heat source and low-alloy high-strength steel powder-core wire as filler metal. By controlling the movement trajectory of the arc welding torch through a program, the molten metal is deposited layer by layer along a preset path, thereby achieving the rapid overall forming of large and complex low-alloy high-strength steel components. Compared with other manufacturing technologies, low-alloy high-strength steel electric arc additive manufacturing technology has significant advantages in achieving moldless, rapid, and fully dense near-net-shape forming of large-size, high-performance, and complex metal parts.

[0004] Although arc additive manufacturing technology shows broad application prospects in the field of low-alloy high-strength steel, there is currently a shortage of dedicated low-alloy high-strength steel wires for arc additive manufacturing. Currently, commercial welding wires are mainly used as substitutes, which are prone to defects such as alloy element burn-off and coarse microstructure during the additive manufacturing process, resulting in poor strength-ductility matching. Furthermore, the selective growth of the microstructure during additive manufacturing leads to significant anisotropy in the mechanical properties of the components, limiting the application and promotion of low-alloy high-strength steel arc additive manufacturing technology. Therefore, developing low-alloy high-strength steel wires for arc additive manufacturing with good strength-ductility matching and low anisotropy has significant engineering application value. Summary of the Invention

[0005] The primary technical problem to be solved by this invention is to provide a low-alloy high-strength steel powder core wire for arc additive manufacturing that has excellent mechanical properties and low anisotropy, in response to the shortcomings of the prior art.

[0006] The technical solution adopted by this invention to solve the first technical problem is: a low-alloy high-strength steel powder core wire for arc additive manufacturing, which is composed of core powder and a carbon steel strip encapsulating the core powder, wherein the core powder is composed of alloy components and slag components, characterized in that:

[0007] The alloy composition comprises the following percentages by mass in the core powder: ferrosilicon powder: 1.5-3.0 wt%, electrolytic manganese: 3.5-5.0 wt%, chromium powder: 1.5-3.0 wt%, nickel powder: 7.5-9.5 wt%, ferromolybdenum powder: 6.5-9.0 wt%, ferrovanadium powder: ≤1.2 wt%, with iron powder and unavoidable impurities as the balance.

[0008] The mass percentage of each substance in the core powder of the slag system is as follows: sodium titanate and potassium titanate: 4-7 wt%, bismuth oxide: 1-8 wt%, titanium dioxide: 5-15 wt%, fluoride: 3-10 wt%, potassium feldspar: 2-3 wt%, and aluminum powder: 1-3 wt%.

[0009] Ferrosilicon and electrolytic manganese: In arc additive manufacturing, silicon and manganese mainly function as a combined deoxidizer, producing silicates with low density and low melting point. However, when the content of ferrosilicon and electrolytic manganese is too high, a large number of inclusions will be generated during continuous additive manufacturing. These inclusions are difficult to float to the surface and be discharged quickly in the molten pool, thus remaining inside the material and causing a significant decrease in material properties. Therefore, in this invention, the mass fraction of ferrosilicon is controlled at 1.5-3.0 wt%, and the mass fraction of electrolytic manganese is controlled at 3.5-5.0 wt%.

[0010] Chromium powder can improve material strength while having little impact on ductility and toughness. It can also form a dense oxide film on the steel surface, enhancing corrosion resistance. However, when its content is too high, it will promote carbide precipitation, leading to a decrease in ductility and toughness. Therefore, the chromium-iron mass fraction in this invention is controlled at 1.5-3.0 wt%.

[0011] Nickel powder has the advantages of improving weldability, increasing material strength and toughness. However, if the nickel powder content is too high, it will lead to increased costs and may also cause elemental segregation during arc additive manufacturing, thereby reducing the strength and toughness of the material. Therefore, the nickel powder mass fraction in this invention is controlled at 7.5-9.5 wt%.

[0012] Ferromolybdenum: In arc additive manufacturing, molybdenum strengthens through solid solution and refines grain size, suppressing temper brittleness and overheating tendency caused by thermal cycling. In the alloy system of the low-alloy high-strength steel powder core wire of this invention, molybdenum also weakens texture orientation, thereby reducing the anisotropy of mechanical properties during additive manufacturing. Therefore, the ferromolybdenum mass fraction in this invention is controlled at 6.5-9.0 wt%.

[0013] Ferrovanadium: Vanadium is a strong carbide-forming element. In arc additive manufacturing, the carbides formed by vanadium and carbon can produce precipitation strengthening without impairing the material's ductility and toughness. However, when the vanadium content is too high, it can cause severe dendritic segregation during additive manufacturing, leading to a decrease in the material's mechanical properties. Therefore, in this invention, the ferrovanadium mass fraction is controlled below 1.2 wt%.

[0014] Sodium titanate and potassium titanate: As arc stabilizers, titanates effectively regulate the stability and spreadability of the molten pool. They improve the stability of the molten pool by reducing the surface tension of the slag, allowing it to spread more evenly on the surface. When the titanate content is too low, the stability of the molten pool deteriorates, leading to increased arc oscillation and spatter. Simultaneously, the spreadability of the slag is also affected, resulting in uneven molten pool coverage. Conversely, when the titanate content is too high, the viscosity of the slag increases, the slag removal ability deteriorates, and slag residue easily remains on the weld surface, affecting the weld formation quality. Therefore, in this invention, the mass fraction of sodium titanate and potassium titanate is controlled at 4-7 wt%. Their ratio can be empirically adjusted according to individual needs.

[0015] Bismuth oxide reduces surface tension, enhances slag wettability, and improves the desulfurization and deoxidation capabilities of molten slag. However, excessive amounts can lead to brittle weld metal, reduced toughness and plasticity, and may also cause welding defects, affecting the overall quality of the weld. Therefore, this invention strictly controls the mass fraction of bismuth oxide to 1-8 wt%.

[0016] Titanium dioxide: a slag-forming agent, capable of reacting with other components in the slag system to form stable silicate and other compounds. These compounds help regulate the viscosity and flowability of the slag. However, excessive content leads to overly viscous slag, affecting its normal flow and slag removal performance, resulting in a large amount of slag remaining on the weld surface, impacting the weld's appearance quality and subsequent defect detection. Therefore, the titanium dioxide content in this invention is controlled at 5-15 wt%.

[0017] Fluorides: Adjust the viscosity and fluidity of the slag, reducing spatter. They also increase the basicity of the slag, aiding in desulfurization and deoxidation. However, excessively high fluoride content produces toxic and harmful gases and fumes, posing a health hazard to operators and causing porosity in the weld metal. Conversely, excessively low content makes it difficult to effectively regulate the slag's properties. Therefore, the fluoride content in this invention is controlled at 3-10 wt%.

[0018] Potassium feldspar: Improves arc stability and regulates slag viscosity. During welding, potassium feldspar melts and participates in forming slag covering the molten pool surface, preventing the intrusion of harmful gases such as nitrogen and oxygen, thereby reducing welding defects such as porosity and oxidation. Simultaneously, the K₂O in potassium feldspar enhances the stability of arc combustion, reduces spatter, and facilitates arc ignition and sustained continuous and stable combustion. Too low a content will not fully realize these effects. Too high a potassium feldspar content leads to high slag viscosity and difficulty in slag removal. Therefore, this invention controls the potassium feldspar content at 2-3 wt%.

[0019] Aluminum powder has strong deoxidizing ability, reducing oxide inclusions in the weld, improving slag properties, and reducing spatter. Excessive aluminum powder content can cause defects such as porosity, affecting weld quality. Simultaneously, excessive aluminum powder also degrades slag properties and increases spatter during welding. Conversely, insufficient aluminum powder content limits its effects on deoxidation, slag property regulation, and arc stabilization. Therefore, this invention controls the aluminum powder content to 1-3 wt%.

[0020] Preferably, the carbon steel strip has the following mass percentage composition: C≤0.12wt%, Mn≤1.00wt%, Si≤0.75wt%, P≤0.040wt%, S≤0.03wt%, with the balance being Fe and unavoidable impurities.

[0021] Furthermore, the composition and mass ratio of low-alloy high-strength steel metal powder cored wire used in arc additive manufacturing are as follows:

[0022] C: 0.08-0.10wt%, Si: 0.3-1.0wt%, Mn: 0.8-2.0wt%, Cr: 0.3-1.0wt%, Ni: 2.0-2.5wt%, Mo: 0.8-1.3wt%, V≤0.2wt%.

[0023] The second technical problem to be solved by this invention is to address the shortcomings of existing technologies by providing a method for preparing low-alloy high-strength steel powder core wire for arc additive manufacturing, characterized by comprising the following processing steps:

[0024] (1) Mixing and drying of the core powder: The weighed core powder is put into a V-type mixer and mixed evenly. The mixed core powder is then put into a drying equipment to dry.

[0025] (2) Filling the core powder: punch the carbon steel strip into a U-shape, then put the core powder from step (1) into the U-shaped groove for filling, and then close the U-shaped groove by pressing.

[0026] (3) Welding wire drawing and sizing: The closed carbon steel strip is initially drawn to gradually reduce its diameter, and then multiple drawing passes are performed to sizing the wire.

[0027] Preferably, the drying temperature of the herbal core powder in step (1) is 80-120℃ and the drying time is 1-3 hours.

[0028] Preferably, in step (2), the carbon steel strip has a width of 9-12 mm, a thickness of 0.4-0.6 mm, and a core powder filling rate of 20%-28%.

[0029] Preferably, the diameter after the initial drawing in step (3) is 4-5 mm, and then it is drawn into a welding wire with a diameter of 0.9-1.4 mm through multiple sizing passes.

[0030] Preferably, the particle size of each substance in the core powder of the medicine in step (1) is 100-200 mesh, so as to ensure that the particle size of the medicine powder is uniform.

[0031] The low-alloy high-strength steel flux-cored wire prepared in this invention was used in a single-pass multilayer forming experiment of arc additive manufacturing using a Fonnière cold metal transfer welding power source. The substrate was a Q235 steel plate with a thickness of 15 mm. Carbon dioxide was used as the shielding gas, with a wire feed speed of 6-7 m / min, a welding torch travel speed of 6-7 mm / s, and a gas flow rate of 15-20 L / min. Horizontal tensile specimens were taken along the welding torch travel direction, and vertical tensile specimens were taken along the deposition direction. Tensile tests were performed three times in both directions, and the average value was calculated. Then, the anisotropy was evaluated.

[0032] This invention quantifies the influence of deposition on the anisotropic behavior of tensile properties of low-alloy high-strength steel flux-cored wires, and its anisotropy rate is defined as:

[0033]

[0034] Where, σ HT and σ VT These represent the tensile properties (e.g., yield strength, tensile strength, elongation) in the horizontal and vertical directions, respectively.

[0035] The advantages of this invention are:

[0036] This invention addresses the arc additive manufacturing of low-alloy high-strength steel by designing a specialized metal powder core wire composition. The core of this design lies in precisely controlling the molybdenum content to suppress grain growth in the martensitic matrix of the aggregate by delaying dislocation annihilation and subgrain formation, while ensuring good formability. This promotes the transformation of coarse columnar grains into equiaxed grains, thereby weakening the preferred grain orientation. This design utilizes a grain refinement strengthening mechanism to improve material strength while maintaining good plasticity.

[0037] The low-alloy high-strength steel powder-core wire prepared by this invention exhibits excellent process stability during arc additive manufacturing. Its droplet transition is smooth and stable, greatly improving the forming quality. Simultaneously, this wire achieves a perfect combination of high precision and high efficiency in manufacturing, demonstrating excellent forming accuracy and efficiency, making it suitable for arc additive manufacturing of low-alloy high-strength steel components.

[0038] The low-alloy high-strength steel powder core wire of the present invention exhibits excellent strength-plasticity matching in the cladding metal deposition state during arc additive manufacturing, and has a low anisotropy rate in tensile properties. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the sampling location of a single-pass multilayer deposition unit as an embodiment or comparative example of the present invention;

[0040] Figure 2 This is a schematic diagram of the tensile specimen dimensions of a single-pass multilayer deposition component, which is an embodiment and comparative example of the present invention. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to specific embodiments.

[0042] The composition of the cladding metal for low-alloy high-strength steel manufactured by electric arc additive manufacturing in three embodiments of the present invention is shown in Table 1.

[0043] Example 1

[0044] Low-alloy high-strength steel powder cored wire for arc additive manufacturing consists of flux powder and a carbon steel strip encapsulating the flux powder. The flux powder is composed of alloy components and slag components, as detailed below:

[0045] The alloy composition comprises the following components by mass percentage in the core powder: ferrosilicon: 2.96 wt%, electrolytic manganese: 4.91 wt%, ferrochrome: 2.85 wt%, nickel powder: 9.32 wt%, ferromolybdenum powder: 6.74 wt%, ferrovanadium: 1.18 wt%, and iron powder as the balance.

[0046] The mass percentages of each substance in the slag system relative to the core powder are as follows: sodium titanate and potassium titanate: 5.2 wt%, bismuth oxide: 4.1 wt%, titanium dioxide: 14.5 wt%, fluoride: 6.8 wt%, potassium feldspar: 3 wt%, and aluminum powder: 3 wt%.

[0047] The particle size of each substance in the core powder is 100-200 mesh.

[0048] The carbon steel strip has the following mass percentages: C: 0.093wt%, Mn: 0.89wt%, Si: 0.63wt%, P: 0.01wt%, S: 0.01wt%, with the balance being Fe and unavoidable impurities. The steel strip is 10mm wide and 0.5mm thick.

[0049] The specific steps for preparing low-alloy high-strength steel powder core wire for arc additive manufacturing are as follows:

[0050] (1) Put the weighed core powder into a V-type mixer and stir for more than 5 hours until it is evenly mixed. Then put the mixed core powder into a drying equipment and dry it at 105°C for 2 hours.

[0051] (2) Punch the carbon steel strip into a U-shape, and then put the core powder from step (1) into the U-shaped groove for filling, so that the core powder filling rate is 22%, and then close the U-shaped groove by pressing.

[0052] (3) After the closed carbon steel strip is initially drawn, its diameter is gradually reduced to Φ4. Then, multiple drawing passes are performed for sizing. The drawing diameter changes from Φ3.2→Φ2.8→Φ2.4→Φ1.8→Φ1.4→Φ1.2mm. The strip is then dried and wound into a coil.

[0053] The prepared low-alloy high-strength steel powder-core wire was used for arc additive manufacturing experiments with a Funes CMT welding power source. The substrate was Q235 steel with a thickness of 15 mm. Carbon dioxide was used as the shielding gas, the wire feed speed was 6 m / min (unified control of welding process parameters), the torch travel speed was 6 mm / s, the gas flow rate was 20 L / min, and the interpass dwell time was 90 s. Horizontal tensile specimens were taken along the torch travel direction, and vertical tensile specimens were taken along the deposition direction. Tensile tests were performed three times in both directions, and the average value was calculated. The mechanical properties and anisotropy rates are shown in Tables 2, 3, and 4.

[0054] Example 2

[0055] Low-alloy high-strength steel powder cored wire for arc additive manufacturing consists of flux powder and a carbon steel strip encapsulating the flux powder. The flux powder is composed of alloy components and slag components, as detailed below:

[0056] The alloy composition comprises the following components by mass percentage in the core powder: ferrosilicon: 2.8 wt%, electrolytic manganese: 3.68 wt%, ferrochrome: 2.57 wt%, nickel powder: 7.72 wt%, ferromolybdenum: 8.93 wt%, ferrovanadium: 0.72 wt%, and iron powder as the balance.

[0057] The mass percentages of each substance in the slag system relative to the core powder are as follows: sodium titanate and potassium titanate: 6 wt%, bismuth oxide: 5.6 wt%, titanium dioxide: 10 wt%, fluoride: 7 wt%, potassium feldspar: 2 wt%, and aluminum powder: 3 wt%.

[0058] The particle size of each substance in the core powder is 100-200 mesh.

[0059] The carbon steel strip has the following mass percentages: C: 0.092wt%, Mn: 0.57wt%, Si: 0.48wt%, P: 0.01wt%, S: 0.01wt%, with the balance being Fe and unavoidable impurities. The steel strip is 10mm wide and 0.5mm thick.

[0060] The specific steps for preparing low-alloy high-strength steel powder core wire for arc additive manufacturing are as follows:

[0061] (1) Place the weighed core powder into a V-type mixer and stir for more than 5 hours until it is evenly mixed. Place the mixed core powder into a drying equipment and dry it at 115°C for 2.5 hours.

[0062] (2) Punch the carbon steel strip into a U-shape, and then put the core powder from step (1) into the U-shaped groove for filling, so that the core powder filling rate is 25%, and then close the U-shaped groove by pressing.

[0063] (3) After the closed carbon steel strip is initially drawn, its diameter is gradually reduced to Φ4. Then, multiple drawing passes are performed for sizing. The drawing diameter changes from Φ3.2→Φ2.8→Φ2.4→Φ1.8→Φ1.4→Φ1.2mm. The strip is then dried and wound into a coil.

[0064] The prepared low-alloy high-strength steel powder-core wire was used for arc additive manufacturing experiments with a Funes CMT welding power source. The substrate was Q235 steel with a thickness of 15 mm. Carbon dioxide was used as the shielding gas, the wire feed speed was 6 m / min (unified control of welding process parameters), the torch travel speed was 6 mm / s, the gas flow rate was 20 L / min, and the interpass dwell time was 90 s. Horizontal tensile specimens were taken along the torch travel direction, and vertical tensile specimens were taken along the deposition direction. Tensile tests were performed three times in both directions, and the average value was calculated. The mechanical properties and anisotropy rates are shown in Tables 2, 3, and 4.

[0065] Example 3

[0066] Low-alloy high-strength steel powder cored wire for arc additive manufacturing consists of flux powder and a carbon steel strip encapsulating the flux powder. The flux powder is composed of alloy components and slag components, as detailed below:

[0067] The alloy composition comprises the following components by mass percentage in the core powder: ferrosilicon: 2.48 wt%, electrolytic manganese: 4.07 wt%, ferrochrome: 2.1 wt%, nickel powder: 7.63 wt%, ferromolybdenum: 6.6 wt%, ferrovanadium: 0.82 wt%, and iron powder as the balance.

[0068] The mass percentage of each substance in the slag system relative to the core powder is as follows: sodium titanate and potassium titanate: 6 wt%, bismuth oxide: 5.6 wt%, titanium dioxide: 15 wt%, fluoride: 7 wt%, potassium feldspar: 2.5 wt%, and aluminum powder: 2.5 wt%.

[0069] The particle size of each substance in the core powder is 100-200 mesh.

[0070] The carbon steel strip has the following mass percentages: C: 0.08wt%, Mn: 0.9wt%, Si: 0.6wt%, P: 0.01wt%, S: 0.01wt%, with the balance being Fe and unavoidable impurities. The steel strip is 10mm wide and 0.5mm thick.

[0071] The specific steps for preparing low-alloy high-strength steel powder core wire for arc additive manufacturing are as follows:

[0072] (1) Place the weighed core powder into a V-type mixer and stir for more than 5 hours until it is evenly mixed. Place the mixed core powder into a drying equipment and dry it at 115°C for 2.5 hours.

[0073] (2) Punch the carbon steel strip into a U-shape, and then put the core powder from step (1) into the U-shaped groove for filling, so that the core powder filling rate is 27%, and then close the U-shaped groove by pressing.

[0074] (3) After the closed carbon steel strip is initially drawn, its diameter is gradually reduced to Φ4. Then, multiple drawing passes are performed for sizing. The drawing diameter changes from Φ3.2→Φ2.8→Φ2.4→Φ1.8→Φ1.4→Φ1.2mm. The strip is then dried and wound into a coil.

[0075] The prepared low-alloy high-strength steel powder-core wire was used for arc additive manufacturing experiments with a Funes CMT welding power source. The substrate was Q235 steel with a thickness of 15 mm. Carbon dioxide was used as the shielding gas, the wire feed speed was 6 m / min (unified control of welding process parameters), the torch travel speed was 6 mm / s, the gas flow rate was 20 L / min, and the interpass dwell time was 90 s. Horizontal tensile specimens were taken along the torch travel direction, and vertical tensile specimens were taken along the deposition direction. Tensile tests were performed three times in both directions, and the average value was calculated. The mechanical properties and anisotropy rates are shown in Tables 2, 3, and 4.

[0076] Using commercially available low-alloy high-strength steel ER120S-G welding wire as a comparative example, the chemical composition of the deposited material after arc additive manufacturing is shown in Table 1. Arc additive manufacturing forming experiments were conducted using a Fonnius CMT welding power source. The substrate was Q235 steel with a thickness of 15 mm. Carbon dioxide was used as the shielding gas, with a wire feed speed of 6 m / min (unified control of welding process parameters), a torch travel speed of 6 mm / s, a gas flow rate of 20 L / min, and an interpass dwell time of 90 s. Horizontal tensile specimens were taken along the torch travel direction, and vertical tensile specimens were taken along the deposition direction. Tensile tests were performed three times in both directions, and the average value was calculated. The mechanical properties and anisotropy rates are shown in Tables 2, 3, and 4.

[0077] Table 1. Alloy composition obtained after arc additive manufacturing in the examples and comparative examples.

[0078]

[0079] Table 2 shows the results of performance tests in the horizontal direction of the weld metal deposited in the arc additive manufacturing of steel wire in the examples and comparative examples.

[0080]

[0081] Table 3 shows the results of performance tests in the vertical direction of the weld metal deposited in the arc additive manufacturing of steel wire in the examples and comparative examples.

[0082]

[0083] Table 4 shows the calculation results of the anisotropy rate of the properties of the weld metal in two directions of the arc additive manufacturing of steel wire in the examples and comparative examples.

[0084]

[0085] The low-alloy high-strength steel powder core wire prepared by this invention has low cost, good stability of the electric arc additive manufacturing process, and excellent forming accuracy and forming efficiency. It is particularly suitable for the electric arc additive manufacturing of low-alloy high-strength steel components.

[0086] The low-alloy high-strength steel powder-core wire prepared by this invention for arc additive manufacturing of cladding metal not only possesses excellent strength-ductility matching but also exhibits low anisotropy in tensile properties. Compared to the comparative example, the low-alloy ultra-high-strength steel powder-core wire arc additive manufacturing of the present invention shows higher strength and elongation after fracture, and lower anisotropy in transverse and longitudinal tensile properties. The tensile strength in the packed state can reach over 840 MPa in both transverse and longitudinal directions, and the yield strength can reach over 540 MPa, while the elongation remains above 14%. The anisotropy rates of tensile strength, yield strength, and elongation in the transverse and longitudinal directions are less than 2%, 8%, and 30%, respectively.

[0087] The technical means disclosed in this invention are not limited to those disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are all considered to be within the scope of protection of this invention.

Claims

1. A low-alloy high-strength steel powder core wire for arc additive manufacturing, comprising a core powder and a carbon steel strip encapsulating the core powder, wherein the core powder comprises an alloy component and a slag component, characterized in that: The mass percentage of each substance in the alloy composition relative to the core powder is as follows: ferrosilicon powder: 1.5-3.0 wt%, electrolytic manganese: 3.5-5.0 wt%, chromium powder: 1.5-3.0 wt%, nickel powder: 7.5-9.5 wt%, ferromolybdenum powder: 6.5-9.0 wt%, ferrovanadium powder: ≤1.2 wt%, with iron powder and unavoidable impurities as the balance; The mass percentage of each substance in the core powder of the slag system is as follows: sodium titanate and potassium titanate: 4-7 wt%, bismuth oxide: 1-8 wt%, titanium dioxide: 5-15 wt%, fluoride: 3-10 wt%, potassium feldspar: 2-3 wt%, and aluminum powder: 1-3 wt%.

2. The low-alloy high-strength steel powder core wire for arc additive manufacturing according to claim 1, characterized in that: The mass percentage composition of the packing is as follows: C: 0.08-0.10wt%, Si: 0.3-1.0wt%, Mn: 0.8-2.0wt%, Cr: 0.3-1.0wt%, Ni: 2.0-2.5wt%, Mo: 0.8-1.3wt%, V≤0.2wt%.

3. The low-alloy high-strength steel powder core wire for arc additive manufacturing according to claim 1, characterized in that: The carbon steel strip has the following mass percentage composition: C≤0.12wt%, Mn≤1.00wt%, Si≤0.75wt%, P≤0.040%, S≤0.03wt%, with the balance being Fe and unavoidable impurities.

4. A method for preparing low-alloy high-strength steel powder core wire for arc additive manufacturing as described in any one of claims 1 to 3, characterized in that: The preparation steps for this low-alloy high-strength steel powder core wire are as follows: (1) Mixing and drying of the core powder: The weighed core powder is put into a V-type mixer and mixed evenly. The mixed core powder is then put into a drying equipment to dry. (2) Filling the core powder: punch the carbon steel strip into a U-shape, then put the core powder from step (1) into the U-shaped groove for filling, and then close the U-shaped groove by pressing. (3) Welding wire drawing and sizing: The closed carbon steel strip is initially drawn to gradually reduce its diameter, and then multiple drawing passes are performed to sizing the wire.

5. The method for preparing low-alloy high-strength steel powder core wire for arc additive manufacturing according to claim 4, characterized in that: The drying temperature of the Chinese medicine core powder in step (1) is 80-120℃, and the drying time is 1-3 hours.

6. The method for preparing low-alloy high-strength steel powder core wire for arc additive manufacturing according to claim 4, characterized in that: In step (2), the carbon steel strip has a width of 9-12 mm, a thickness of 0.4-0.6 mm, and a core powder filling rate of 20%-28%.

7. The method for preparing low-alloy high-strength steel powder core wire for arc additive manufacturing according to claim 4, characterized in that: In step (3), the initial diameter after drawing is 4-5 mm, and then multiple passes of sizing drawing are used to produce welding wire with a diameter of 0.9-1.4 mm.

8. The method for preparing low-alloy high-strength steel powder core wire for arc additive manufacturing according to claim 4, characterized in that: In step (1), the particle size of each substance in the core powder is 100-200 mesh to ensure uniform particle size of the powder.

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