A flux for H-shaped steel double-wire submerged arc deep penetration welding, a preparation method thereof and a welding method

Abstract

This invention discloses a flux for double-wire submerged arc deep penetration welding of H-beams, its preparation method, and welding method. The flux raw materials include magnesite, wollastonite, white corundum, manganese oxide powder, mica, kaolin, titanium diboride powder, zircon, and scandium oxide powder. The flux composition, by mass percentage, includes: MgO: 10%–25%; Al2O3: 25%–40%; SiO2: 15%–30%; P: ≤0.02%; S: ≤0.02%; K2O: ≤3%; CaO: 3%–10%; TiB2: 1%–5%; MnO: 6%–10%; Fe2O3: 1%–6%; ZrO2: 3%–8%; Sc2O3: 1%–3%. The flux of this invention protects the weld metal from harmful gases in the surrounding atmosphere when it is in the liquid state, eliminating welding defects such as porosity, slag inclusions, undercut, and cracks, ensuring full penetration of the web, good fusion of the flanges and weld formation, and improving the strength and toughness of the weld by transition alloying elements.

Description

Technical Field

[0001] This invention relates to a welding technology, and more particularly to a flux for double-wire submerged arc deep penetration welding of H-beams, its preparation method, and welding method. Background Technology

[0002] H-beams are characterized by their parallel flanges on both the inner and outer sides, with right-angled flange ends, hence the name "parallel flange H-beams." H-beams have a thinner web than ordinary H-beams, but wider flanges. In various metal structures, H-beams offer superior pressure load capacity, bending resistance, and compressive strength. Under the same load-bearing capacity, they can save 10% to 40% of metal. Due to their wide flanges, thin web, numerous specifications, and flexible application, H-beams are widely used in various truss structures. The traditional method of welding H-beams involves assembling a pair of flanges to the web. However, this method is labor-intensive, often resulting in insufficient weld penetration, severely affecting the joint strength and impact toughness. Furthermore, external environmental factors or unstable impurities can also affect weld penetration. Therefore, strict control of welding process parameters is necessary during H-beam production. Current welding methods for H-beams mainly involve multi-layer, multi-pass welding, which is complex and inefficient. While twin-wire submerged arc welding can achieve one-time forming of H-beams, it suffers from poor strength-toughness matching in fillet welds. For example, the raw materials for traditional high-efficiency submerged arc welding sintered flux include the following components: bauxite (Al2O3), magnesia (MgO), wollastonite (Al2O3, SiO2), fluorite (CaF2), refractory clay (Al2O3, SiO2), kaolin (Al2O3, K2O, CaO, TiO2, Fe2O3), and ferrosilicon (SiFe). Specifically, the composition includes: SiO2: 15%–25%; CaF2: 15%–25%; Al2O3: 15%–25%; Fe2O3: 0%–1%; (MgO, CaO): 25%–40%; TiO2: 3%–6%; K2O: 1%–3%; SiFe: 1%–2%. However, during H-beam welding, as the welding heat input increases, the sintered flux is prone to slag adhesion, poor arc stability, resulting in undercut, spatter, and unattractive weld formation. The weld is also prone to having a coarse proeutectoid ferrite structure, leading to a decrease in the mechanical properties of the weld. Summary of the Invention

[0003] Purpose of the invention: The present invention aims to provide a flux for double-wire submerged arc deep penetration welding of H-beams with good weld formation, free from porosity, slag inclusions, and undercut, and with good mechanical properties of the welded joint, as well as its preparation method and welding method.

[0004] Technical solution: The present invention provides a flux for double-wire submerged arc deep penetration welding of H-beams, wherein the flux raw materials include magnesite, wollastonite, white corundum, manganese oxide powder, mica, kaolin, titanium diboride powder, zircon, and scandium oxide powder.

[0005] Preferably, the flux composition, by mass percentage, includes: MgO: 10%–25%; Al2O3: 25%–40%; SiO2: 15%–30%; P: ≤0.02%; S: ≤0.02%; K2O: ≤3%; CaO: 3%–10%; TiB2: 1%–5%; MnO: 6%–10%; Fe2O3: 1%–6%; ZrO2: 3%–8%; Sc2O3: 1%–3%.

[0006] Preferably, the flux composition, by mass percentage, comprises: MgO: 17.02%; Al2O3: 34.32%; SiO2: 20.87%; P: 0.017%; S: 0.013%; K2O: 0.26%; CaO: 9.47%; TiB2: 1.73%; MnO: 8.15%; Fe2O3: 2.74%; ZrO2: 3.41%; Sc2O3: 2%; LOI: -0.33%.

[0007] The present invention discloses a method for preparing a flux for double-wire submerged arc deep penetration welding of H-beams, comprising the following steps:

[0008] (1) Prepare the raw materials according to the mass percentage and mix them for 10-20 minutes using a V-type mixer to ensure they are mixed evenly and thoroughly. The mixing speed of the mixer is 100-150 r / min. The raw materials, by mass percentage, include: MgO: 10%-25%; Al2O3: 25%-40%; SiO2: 15%-30%; P: ≤0.02%; S: ≤0.02%; K2O: ≤3%; CaO: 3%-10%; TiB2: 1%-5%; MnO: 6%-10%; Fe2O3: 1%-6%; ZrO2: 3%-8%; Sc2O3: 1%-3%.

[0009] (2) The mixed raw materials are granulated using an alkaline binder and then dried in a dryer at 300-350°C.

[0010] (3) The dried flux is placed into an inclined mixing granulator for dispersion and refining, and then screened to sort out qualified particles of 20-70 mesh.

[0011] (4) The dried and screened flux is placed in a high-temperature sintering furnace and sintered at 800-900℃ for 1.5-2 hours. After cooling, the finished sintered flux is formed.

[0012] Preferably, the raw materials, by mass percentage, comprise: MgO: 17.02%; Al2O3: 34.32%; SiO2: 20.87%; P: 0.017%; S: 0.013%; K2O: 0.26%; CaO: 9.47%; TiB2: 1.73%; MnO: 8.15%; Fe2O3: 2.74%; ZrO2: 3.41%; Sc2O3: 2%; LOI: -0.33%.

[0013] Preferably, the alkaline binder comprises potassium silicate and soda ash, with a mass ratio of potassium silicate to soda ash of 2:1. Using an alkaline binder allows for more uniform mixing with the raw materials, resulting in better flowability of the mixed materials. Adding soda ash can increase the granulation rate of the raw materials, making the particle size smaller and more uniform; it can also improve the thermal stability of the raw materials, lower the sintering temperature, and shorten the sintering time.

[0014] This invention discloses a double-wire submerged arc deep penetration welding method for H-beams, which enables good formation of H-beam fillet welds, improves the mechanical properties of H-beam welds, and extends their service life. Specifically, it includes: using welding wire in conjunction with the aforementioned sintered flux, performing double-wire submerged arc deep penetration welding at a 45° angle to the hull position of the fillet weld between the flange and web of the H-beam; the welded joint is a full penetration H-beam without beveling; the welding wire material has the following composition by mass percentage: C: ≤0.12%; Mn: 1.50%~1.90%; Si: ≤0.07%; Cr: ≤0.20%; Ni: ≤0.30%; Cu: ≤0.20%; S: ≤0.035%; P: ≤0.035%.

[0015] Preferably, the welding current of the front wire is 950-1100A, the welding current of the rear wire is 700-850A; the welding voltage of the front wire is 31-32V, the welding voltage of the rear wire is 37-38V; the spacing between the front and rear welding wires is 15-20mm; and the welding speed is 420-430mm / min.

[0016] Preferably, the welding wire is a solid core welding wire of type H10Mn2.

[0017] The main components of the sintering flux of this invention have the following functions: MgO: It increases the viscosity of the slag; 10%–25% MgO can improve its slag removal properties and increase the melting point of the sintering flux; Al2O3: During sintering, Al2O3 can promote the formation of an infinite solid solution, leading to lattice distortion, thereby activating the lattice and significantly promoting sintering; SiO2: Its main function is slag formation, reacting with impurity elements and oxide films to eliminate the influence of impurity elements and oxide films on the mechanical properties of the weld; MnO and K2O: Their main functions are to dilute the slag, increase the reducing power of the flux, and improve the basicity of the flux; CaO: A small amount of CaO can help form a dense microstructure with uniform and fine grains. The structure of the weld joint is improved by transferring harmful elements such as P and S into the weld slag shell, thus enhancing the impact toughness of the weld joint. Fe2O3 primarily functions as slag-forming material, improving the slag removal properties of the sintered flux, increasing the melting point of the weld, reducing the high-temperature viscosity of the molten slag, and improving the mechanical properties of the weld. TiB2, a hexagonal quasi-metallic compound and a novel functional material, effectively transfers alloying elements into the weld, increasing its strength and making the weld surface smoother and shinier. ZrO2, with small amounts, can transfer into the weld, refining the weld microstructure and improving its mechanical properties. Sc2O3 promotes the spheroidization process of the molten slag, improves the slag removal properties of the weld, and a small amount can refine the weld microstructure. The weld joint not only possesses good chemical and thermal stability but also a strong crystal field. The rare earth element Sc can enhance the high-temperature fracture toughness and bending strength of the weld, while simultaneously transforming the monoclinic phase of ZrO2 into a more stable tetragonal phase, thereby enhancing the weld strength.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0019] 1. The sintered flux of the present invention has a low bulk density, a thin and brittle slag shell that is easy to clean, low flux consumption, and excellent slag removal properties. It facilitates the transport and recycling of flux during the welding process, resulting in low welding production costs. Furthermore, it improves the mechanical properties of the weld during the welding process, isolates air to prevent weld defects, ensures good and beautiful weld formation, and achieves a penetration depth of up to 20mm with 100% full penetration. After ultrasonic flaw detection, the weld is free of porosity, slag inclusions, internal cracks, and other defects. The weld is smooth and has high application value.

[0020] 2. In the process of dual-wire submerged arc welding, firstly, it protects the weld metal from harmful gases in the surrounding atmosphere while it is in a liquid state, ensuring good weld formation; secondly, it improves the quality of weld formation; and thirdly, it strengthens the weld performance through alloy strengthening treatment, i.e., dissolving the required alloying elements during the welding process. The sintered flux of this invention, when used with H10Mn2 solid core welding wire, can achieve efficient and reliable welding of H-beams under optimal welding process parameters. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the welding position for double-wire submerged arc deep penetration welding of web H-beams in an embodiment of the present invention;

[0022] Figure 2 This is a schematic diagram of the weld formation of the outer corner weld between the flange and web of an H-beam obtained by sintering flux welding in Embodiment 3 of the present invention.

[0023] Figure 3 This is a schematic diagram of the weld formation of the inner corner weld between the flange and web of an H-beam obtained by sintering flux welding in Embodiment 3 of the present invention.

[0024] Figure 4 This is a schematic diagram of the full penetration cross-section of the flange and web of the H-beam obtained by sintering flux welding in Embodiment 3 of the present invention. Detailed Implementation

[0025] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0026] The flux for double-wire submerged arc deep penetration welding of H-beams described in this invention comprises magnesia (MgO), wollastonite (SiO2), white corundum (Al2O3), manganese oxide powder (MnO), mica (Al2O3, SiO2), kaolin (Al2O3, K2O, CaO, Fe2O3), titanium diboride powder (TiB2), zircon (SiO2, ZrO2), and scandium oxide powder (Sc2O3). Its composition, by mass percentage, includes: MgO: 10%–25%; Al2O3: 25%–40%; SiO2: 15%–30%; P: ≤0.02%; S: ≤0.02%; K2O: ≤3%; CaO: 3%–10%; TiB2: 1%–5%; MnO: 6%–10%; Fe2O3: 1%–6%; ZrO2: 3%–8%; Sc2O3: 1%–3%.

[0027] Preferably, the flux composition, by mass percentage, comprises: MgO: 17.02%; Al2O3: 34.32%; SiO2: 20.87%; P: 0.017%; S: 0.013%; K2O: 0.26%; CaO: 9.47%; TiB2: 1.73%; MnO: 8.15%; Fe2O3: 2.74%; ZrO2: 3.41%; Sc2O3: 2%; LOI: -0.33%.

[0028] The present invention discloses a method for preparing a flux for double-wire submerged arc deep penetration welding of H-beams, comprising the following steps:

[0029] (1) Prepare the raw materials according to the above composition and mass percentage, and use a V-type mixer to mix for 10 to 20 minutes to make them even and thorough. The mixing speed of the mixer is 100 r / min to 150 r / min.

[0030] (2) The mixed raw materials are granulated using an alkaline binder and then dried in a dryer at 300-350°C; the alkaline binder includes potassium silicate and soda ash, with a mass ratio of potassium silicate to soda ash of 2:1.

[0031] (3) The dried flux is placed into an inclined mixing granulator for dispersion and refining, and then screened to sort out qualified particles of 20-70 mesh.

[0032] (4) The dried and screened flux is placed in a high-temperature sintering furnace and sintered at 800-900℃ for 1.5-2 hours. After cooling, the finished sintered flux is formed.

[0033] The present invention discloses a welding method for double-wire submerged arc deep penetration welding of H-beams, comprising: using welding wire in conjunction with the aforementioned sintered flux, performing double-wire submerged arc deep penetration welding at a 45° angle to the hull position of the fillet weld between the flange and web of the H-beam, wherein the welded joint is a full penetration H-beam without beveling; the welding wire material has the following composition by mass percentage: C: ≤0.12%; Mn: 1.50%~1.90%; Si: ≤0.07%; Cr: ≤0.20%; Ni: ≤0.30%; Cu: ≤0.20%; S: ≤0.035%; P: ≤0.035%. Preferably, the welding wire is a solid core welding wire of type H10Mn2, with a front wire diameter of 3.2-5.0 mm and a rear wire diameter of 4.0-5.0 mm; the welding process parameters include: the welding current of the front wire is 950-1100A, the welding current of the rear wire is 700-850A; the welding voltage of the front wire is 31-32V, the welding voltage of the rear wire is 37-38V; the spacing between the front and rear welding wires is 15-20 mm; and the welding speed is 420-430 mm / min.

[0034] Example 1

[0035] The flux for double-wire submerged arc deep penetration welding of H-beams described in this invention comprises, by mass percentage: MgO: 11%; Al2O3: 33%; SiO2: 27.21%; P: 0.015%; S: 0.015%; K2O: 1.1%; CaO: 9.05%; TiB2: 1.7%; MnO: 7%; Fe2O3: 3.12%; ZrO2: 4.11%; Sc2O3: 2.68%; LOI: 0%.

[0036] Its preparation method includes the following steps:

[0037] (1) Mix the above raw materials according to the mass percentage, put them into a V-type mixer and mix for 10 minutes to make them fully and evenly mixed.

[0038] (2) The mixed raw materials are granulated using an alkaline binder with a mass ratio of potassium silicate to soda ash of 2:1, and then placed in a dryer and dried at 300°C.

[0039] (3) The dried flux is placed into an inclined mixing granulator for dispersion and refinement, and then screened to sort out 40-mesh qualified particles.

[0040] (4) The dried and screened flux is placed in a high-temperature sintering furnace and sintered at 800°C for 1.5 hours. After cooling, the finished sintered flux is formed.

[0041] Example 2

[0042] The flux for double-wire submerged arc deep penetration welding of H-beams described in this invention comprises, by mass percentage: MgO: 21%; Al2O3: 25.35%; SiO2: 29.59%; P: 0.012%; S: 0.018%; K2O: 1%; CaO: 3.5%; TiB2: 1.9%; MnO: 10%; Fe2O3: 2%; ZrO2: 4%; Sc2O3: 1.63%; LOI: 0%.

[0043] Its preparation method includes the following steps:

[0044] (1) Mix the above raw materials according to the mass percentage, put them into a V-type mixer and mix for 15 minutes to make them fully and evenly mixed.

[0045] (2) The mixed raw materials are granulated using an alkaline binder with a mass ratio of potassium silicate to soda ash of 2:1, and then placed in a dryer and dried at 330°C.

[0046] (3) The dried flux is placed into an inclined mixing granulator for dispersion and refining, and then screened to sort out 50-mesh qualified particles.

[0047] (4) The dried and screened flux is placed in a high-temperature sintering furnace and sintered at 850°C for 1.5 hours. After cooling, the finished sintered flux is formed.

[0048] Example 3

[0049] The flux for double-wire submerged arc deep penetration welding of H-beams described in this invention comprises, by mass percentage: MgO: 17.02%; Al2O3: 34.32%; SiO2: 20.87%; P: 0.017%; S: 0.013%; K2O: 0.26%; CaO: 9.47%; TiB2: 1.73%; MnO: 8.15%; Fe2O3: 2.74%; ZrO2: 3.41%; Sc2O3: 2%; LOI: -0.33%.

[0050] Its preparation method includes the following steps:

[0051] (1) Mix the above raw materials according to the mass percentage, put them into a V-type mixer and mix for 20 minutes to make them fully and evenly mixed.

[0052] (2) The mixed raw materials are granulated using an alkaline binder with a mass ratio of potassium silicate to soda ash of 2:1, and then placed in a dryer and dried at 350°C.

[0053] (3) The dried flux is placed into an inclined mixing granulator for dispersion and refinement, and then 60-mesh qualified particles are screened and sorted out.

[0054] (4) The dried and screened flux is placed in a high-temperature sintering furnace and sintered at 800°C for 2 hours. After cooling, the finished sintered flux is formed.

[0055] Example 4

[0056] The flux for double-wire submerged arc deep penetration welding of H-beams described in this invention comprises, by mass percentage: MgO: 16.5%; Al2O3: 38.42%; SiO2: 16.55%; P: 0.01%; S: 0.02%; K2O: 0.5%.

[0057] CaO: 6.18%; TiB2: 4.07%; MnO: 6.95%; Fe2O3: 1.35%; ZrO2: 7.35%; Sc2O3: 2.1%; LOI: -0.05%;

[0058] Its preparation method includes the following steps:

[0059] (1) Mix the above raw materials according to the mass percentage, put them into a V-type mixer and mix for 12 minutes to make them fully and evenly mixed.

[0060] (2) The mixed raw materials are granulated using an alkaline binder with a mass ratio of potassium silicate to soda ash of 2:1, and then placed in a dryer and dried at 320°C.

[0061] (3) The dried flux is placed into an inclined mixing granulator for dispersion and refining, and then screened to sort out qualified 30-mesh particles.

[0062] (4) The dried and screened flux is placed in a high-temperature sintering furnace and sintered at 900°C for 1.5 hours. After cooling, the finished sintered flux is formed.

[0063] Example 5

[0064] The flux for double-wire submerged arc deep penetration welding of H-beams described in this invention comprises, by mass percentage: MgO: 23%; Al2O3: 31.25%; SiO2: 15.5%; P: 0.01%; S: 0.01%; K2O: 2.17%; CaO: 9.43%; TiB2: 1.5%; MnO: 6.63%; Fe2O3: 5.71%; ZrO2: 3.64%; Sc2O3: 1.15%; LOI: 0%.

[0065] Its preparation method includes the following steps:

[0066] (1) Mix the above raw materials according to the mass percentage, put them into a V-type mixer and mix for 18 minutes to make them fully and evenly mixed.

[0067] (2) The mixed raw materials are granulated using an alkaline binder with a mass ratio of potassium silicate to soda ash of 2:1, and then placed in a dryer and dried at 300°C.

[0068] (3) The dried flux is placed into an inclined mixing granulator for dispersion and refinement, and then screened to sort out 40-mesh qualified particles.

[0069] (4) The dried and screened flux is placed in a high-temperature sintering furnace and sintered at 850°C for 1.5 hours. After cooling, the finished sintered flux is formed.

[0070] For Examples 1-5, double-wire submerged arc deep penetration welding was used with H10Mn2 welding wire (the composition range of the material was determined based on the steel plate used in this welding test: C: ≤0.12%; Mn: 1.50%~1.90%; Si: ≤0.07%; Cr: ≤0.20%; Ni: ≤0.30%; Cu: ≤0.20%; S: ≤0.035%; P: ≤0.035%), and welded with the corresponding sintered flux at a 45° angle to the fillet weld of the H-beam flange and web of a 20mm web. Figure 1 As shown in Table 1-2, the experimental setup and welding process parameters used are as follows.

[0071] Table 1 Test Setup

[0072] Equipment Name Power supply model Nose type test platform Twin-wire submerged arc welding machine ZD7-1250G+ZDE7-1000G Multi-wire submerged arc welding head Multi-filament test platform

[0073] Table 2 Welding process parameters

[0074]

[0075] Through the above experiments, taking the weld formation of Example 3 as an example, as shown... Figure 2-4 As shown, ultrasonic testing revealed no porosity, cracks, or slag inclusions inside the weld. Therefore, the welding arc was stable and slag removal was excellent during the welding of H-beams, resulting in a beautiful weld formation, weld penetration meeting design requirements, and no welding defects.

[0076] To further verify the present invention, comparative examples 1-5 were set up. Comparative example 1 used a common sintered flux, and the flux composition, by mass percentage, included: MgO: 18%; SiO2: 12%; CaF2: 20%; TiO2: 5%; Al2O3: 22%; Fe2O3: 0.5%; K2O: 2%; CaO: 19%; SiFe: 1.5%. Its flux composition differs from that of the present invention. The flux compositions of comparative examples 2-5 are the same as those of the present invention, and their formulations are shown in Table 3.

[0077] Table 3 shows the chemical composition of comparative examples 2–5 (rounded to the nearest integer).

[0078]

[0079]

[0080] For Examples 1-5 and Comparative Examples 1-5, double-wire submerged arc deep penetration welding was used with H10Mn2 welding wire and flux prepared with corresponding components. Welding was performed at 45° to the hull position of the fillet weld between the flange and web of an H-beam with a 20mm web. The welding parameters were as follows: front wire diameter 5.0mm, rear wire diameter 5.0mm; welding current 1050A for the front wire and 800A for the rear wire; welding voltage 32V for the front wire and 38V for the rear wire; welding speed 430mm / min; and wire spacing 20mm. After welding, the mechanical properties of the fillet welds of the H-beam joints in each example and comparative example were tested. The test results are shown in Tables 4 and 5, respectively.

[0081] Table 4 Mechanical property test values ​​of Examples 1-5

[0082] Test number Example 1 Example 2 Example 3 Example 4 Example 5 Yield strength (MPa) 418 421 435 425 432 Tensile strength (MPa) 497 508 535 501 515 Elongation (%) 30 32 33 30 29 Impact absorption energy at 0℃ (J) 116 128 130 121 123

[0083] Table 5 Mechanical property test values ​​for Comparative Examples 1-5

[0084] Test number Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Yield strength (MPa) 343 361 378 374 369 Tensile strength (MPa) 421 479 467 425 428 Elongation (%) 15 25 30 29 31 Impact absorption energy at 0℃ (J) 56 125 119 115 108

[0085] Based on the above mechanical performance test data, the mechanical performance test values ​​of Examples 1-5 are generally better than those of the comparative examples, and Example 3 has the best overall mechanical performance, with beautiful weld formation, weld penetration depth that meets design requirements and no welding defects.

[0086] Specifically, the mechanical property test results of Examples 1-5 and Comparative Example 1 show that during H-beam welding, the ordinary sintered flux in Comparative Example 1 is prone to slag adhesion, poor arc stability, resulting in undercut, spatter, and unattractive weld formation. The weld is also prone to developing coarse proeutectoid ferrite, leading to a decrease in the weld's mechanical properties. The flux of this invention protects the weld metal from harmful gases in the surrounding atmosphere while it is in a liquid state, eliminating welding defects such as porosity, slag inclusions, undercut, and cracks. It ensures full penetration of the web, good fusion of the flanges, and good weld formation. Furthermore, the transition alloying elements improve the weld's strength and toughness. The mechanical property test results of Examples 3 and Comparative Examples 4 and 5 show that when the TiB2 content in the sintered flux is high, excessive metal compounds are easily generated in the weld, leading to a decrease in the weld's yield strength and tensile strength. When the CaO content is low, the binding ability with impurity elements S and P in the weld metal weakens, resulting in poor joint mechanical properties. In Comparative Example 2, excessive CaO content led to excessive coarse dendrites in the weld microstructure, resulting in porosity and reducing the weld elongation. The mechanical property test results of Comparative Example 3 show that insufficient ZrO2 content and excessive Sc2O3 content resulted in an imbalance, leading to decreased resistance to high-temperature oxidation and weakening the strength of the weld metal.

[0087] To test the impact toughness of the sintered flux of the present invention under low-temperature conditions, a double-wire submerged arc deep penetration welding method was used, employing H10Mn2 welding wire and the flux prepared according to the composition of Example 3. Welding was performed at a 45° angle to the flange and web fillet weld of an H-beam with a 20mm web. The welding parameters were: front wire diameter 4.0mm, rear wire diameter 5.0mm; welding current 1100A for the front wire and 850A for the rear wire; welding voltage 32V for the front wire and 38V for the rear wire; welding speed 430mm / min; and wire spacing 15mm. The results of three tests are shown in Table 6. It can be seen that the sintered flux of the present invention still exhibits good impact toughness under low-temperature conditions.

[0088] Table 6 Low-Temperature Mechanical Property Test Values

[0089]

Claims

1. A flux for double-wire submerged arc deep penetration welding of H-beams, characterized in that, The flux raw materials include magnesite, wollastonite, white corundum, manganese oxide powder, mica, kaolin, titanium diboride powder, zircon, and scandium oxide powder; the flux composition by mass percentage is: MgO: 10%–25%; Al2O3: 25%–40%; SiO2: 15%–30%; P: 0.01%–0.02%; S: 0.01%–0.02%; K2O: ≤3%; CaO: 3%–10%; TiB2: 1%–5%. Composition: MnO: 6%–10%; Fe2O3: 1%–6%; ZrO2: 3%–8%; Sc2O3: 1%–3%.

2. The flux for double-wire submerged arc deep penetration welding of H-beams according to claim 1, characterized in that, The flux composition, by mass percentage, includes: MgO: 17.02%; Al2O3: 34.32%; SiO2: 20.87%; P: 0.017%; S: 0.013%; K2O: 0.26%; CaO: 9.47%; TiB2: 1.73%; MnO: 8.15%; Fe2O3: 2.74%; ZrO2: 3.41%; Sc2O3: 2%; LOI: -0.33%.

3. A method for preparing flux for double-wire submerged arc deep penetration welding of H-beams according to claim 1, characterized in that, Includes the following steps: (1) Mix the raw materials according to the mass percentage and use a V-type mixer to mix for 10 to 20 minutes to make them even and thorough; (2) The mixed raw materials are granulated using an alkaline binder and then dried in a dryer at 300-350°C; (3) The dried flux is placed into an inclined mixing granulator for dispersion and refining, and then screened to sort out qualified particles of 20-70 mesh. (4) The dried and screened flux is placed in a high-temperature sintering furnace and sintered at 800-900℃ for 1.5-2 hours. After cooling, the finished sintered flux is formed.

4. The method for preparing flux for double-wire submerged arc deep penetration welding of H-beams according to claim 3, characterized in that, The raw materials, by mass percentage, comprise: MgO: 17.02%; Al2O3: 34.32%; SiO2: 20.87%; P: 0.017%; S: 0.013%; K2O: 0.26%; CaO: 9.47%; TiB2: 1.73%; MnO: 8.15%; Fe2O3: 2.74%; ZrO2: 3.41%; Sc2O3: 2%; LOI: -0.33%.

5. The method for preparing flux for double-wire submerged arc deep penetration welding of H-beams according to claim 3, characterized in that, The alkaline binder comprises potassium silicate and soda ash, with a mass ratio of potassium silicate to soda ash of 2:

1.

6. A welding method for double-wire submerged arc deep penetration welding of H-beams, characterized in that, include: Using H10Mn2 welding wire and the flux for double-wire submerged arc deep penetration welding of H-beams as described in any of claims 1-2, double-wire submerged arc deep penetration welding is performed at a 45° angle to the hull position of the fillet weld between the flange and web of the H-beam. The welded joint is a full penetration H-beam without beveling. The mass percentage composition of the welding wire is: C: ≤0.12%; Mn: 1.50%~1.90%; Si: ≤0.07%; Cr: ≤0.20%; Ni: ≤0.30%; Cu: ≤0.20%. S: ≤0.035%; P: ≤0.035%.

7. The welding method for double-wire submerged arc deep penetration welding of H-beams according to claim 6, characterized in that, The diameter of the front wire of the welding wire is 3.2-5.0 mm, and the diameter of the rear wire is 4.0-5.0 mm.

8. The welding method for double-wire submerged arc deep penetration welding of H-beams according to claim 7, characterized in that, The welding current for the front wire is 950–1100A, and the welding current for the rear wire is 700–850A; the welding voltage for the front wire is 31–32V, and the welding voltage for the rear wire is 37–38V; the spacing between the front and rear welding wires is 15–20mm; and the welding speed is 420–430mm / min.

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