High-speed flux for fine-wire submerged arc welding of pipeline girth welds and method of making

Abstract

The application discloses a kind of high-speed flux for pipeline girth weld fine wire submerged arc welding and preparation method, including by mass percentage: fluorite 23-26%, calcined coke stone 20-23%, pre-melting calcium aluminate 18-21%, talc powder 12-14%, potassium fluosilicate 5-7%, zirconium-rich iron ore 5-7%, heavy rare earth silicon iron 2.5-4%, carbonized nickel-iron alloy 2-4%.The application meets the demand of multi-fine wire submerged arc welding X90Q pipeline girth weld, has good welding process and post-welding butt joint metal mechanical properties, is widely used in pipeline production industry, greatly improves the production efficiency and life quality of people.

Description

Technical Field

[0001] This invention belongs to the field of submerged arc welding materials technology, and in particular relates to a fine wire high-speed submerged arc welding flux for pipeline circumferential welds and its preparation method. Background Technology

[0002] Submerged arc welding (SAW), as an internationally advanced and efficient welding method, has been introduced and studied by domestic technicians, gradually developing its own capabilities. However, compared to other welding methods, SAW has a relatively short history of practical application in Chinese engineering projects, resulting in a limited variety and limited availability of SAW fluxes. To ensure construction quality and schedule, key domestic projects often require the procurement of imported fluxes. Imported fluxes are expensive, have long delivery cycles, and are subject to technological limitations imposed by foreign welding material manufacturers. Therefore, steel pipe manufacturers urgently require improvements to domestically produced sintered fluxes and the development of corresponding specialized fluxes.

[0003] Welding is a highly complex physicochemical process characterized by high reaction temperatures, short reaction times, and the difficulty in achieving equilibrium among the various reacting phases. Quantitative analysis of the welding metallurgical process remains challenging. Research on the influence of flux components on welding process performance, both domestically and internationally, primarily employs extensive formulation experiments. Therefore, this patent development process utilized numerous experiments to study the effects of flux components on welding process performance and butt joint mechanical properties, and based on these studies, developed a novel sintered flux for pipeline steel.

[0004] Submerged arc welding (SAW) is a welding method that uses the heat generated by an electric arc burning between an electrode and the workpiece under a layer of flux to melt the electrode, flux, and base metal. SAW is characterized by high production efficiency, good weld quality, and ease of automation. In recent years, my country has significantly improved the level of industrial automation in basic pipeline infrastructure construction, and the use of SAW has greatly improved welding production efficiency, reduced labor costs, and improved working conditions for workers.

[0005] In recent years, with the rapid development of my country's economy, infrastructure planning has become more specific and clear, posing significant challenges to my country's industrial production. To meet these challenges, Chinese engineers have developed various types of high-strength pipeline steel, with large demand and high construction efficiency requirements. Furthermore, submerged arc welding (SAW) often requires continuous welding, sometimes even welding multiple seams simultaneously, demanding even higher efficiency. Traditional manual welding electrodes and gas-shielded welding wires are mostly used manually, making automated welding impossible. To resolve these contradictions, submerged arc welding should be adopted, which urgently requires the development of new welding materials. Currently, domestic research on submerged arc welding of high-strength pipeline steel is not in-depth, and there is a significant gap in welding material products that urgently need to be filled. This invention takes a different approach, employing a special slag system that prioritizes ensuring the fluidity of the molten iron in the circumferential weld while also guaranteeing the tensile strength, yield strength, and elongation of the weld metal, thus reducing the weld's tendency to crack. In actual welding operations, this flux is simple to operate, highly automated, easy to remove slag, produces aesthetically pleasing welds, and significantly reduces the labor intensity of workers. Invention Content In view of this, the present invention aims to provide a fine wire high-speed submerged arc welding flux for pipeline circumferential welds and its preparation method, so as to solve at least one technical problem in the background art.

[0006] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A high-speed submerged arc welding flux for pipeline circumferential welds, comprising by weight percentage: 23-26% fluorite, 20-23% calcined charcoal, 18-21% pre-melted calcium aluminate, 12-14% talc, 5-7% potassium fluorosilicate, 5-7% zirconium-rich iron ore, 2.5-4% heavy rare earth ferrosilicon, and 2-4% nickel-iron carbide alloy.

[0007] The fluoride added in this application is mainly fluorite. The main active component of fluorite is CaF2. During welding, calcium fluoride releases gas when the electric arc burns, forming a protective atmosphere around the arc. This ensures uniform melting of the welding wire and optimizes weld bead formation. Furthermore, fluorides like CaF2 effectively reduce the content of harmful gases in the weld metal, preventing welding defects such as porosity and cratering. Adding an appropriate amount of fluoride to the flux also significantly improves the fluidity of the molten metal during welding, but the amount added in the flux formulation must be carefully controlled. Too much will result in excessively thin molten metal, while too little will affect arc stability. Through numerous experiments, the fluorite content in this invention is controlled at 23-26%.

[0008] Furthermore, the calcined char gemstone contains ≥40% SiO2 and ≥42% Al2O3. Calcined char gemstone is a powder obtained from clay ore through grinding or weathering. According to the requirements of the flux according to this invention, NHNT-1 type calcined char gemstone is selected, with SiO2 controlled at ≥40% and Al2O3 controlled at ≥42%. In this formulation, the appropriate addition ratio of calcined char gemstone is 20-23%.

[0009] Furthermore, the pre-melted calcium aluminate contains 60-65% CaO and 25-30% Al2O3. Pre-melted calcium aluminate is a residue produced during blast furnace steelmaking, primarily composed of Al2O3 and CaO. In this formulation, CaAl-30 should be used, meaning the CaO content should be controlled at 60-65% and the Al2O3 content at 25-30%. In this formulation, the appropriate proportion of pre-melted calcium aluminate is 18-21%.

[0010] Furthermore, the pre-melted calcium aluminate is CaAl-30.

[0011] Furthermore, the talc powder should contain SiO2 ≥ 58%, MgO ≥ 29%, Al2O3 ≤ 1.5%, CaO ≤ 1.5%, and Fe2O3 ≤ 1.5%. Talc is a non-metallic mineral, a magnesium silicate mineral belonging to the talc group, with hydrated magnesium silicate as its main component. It is produced by treatment with hydrochloric acid, washing with water, and drying. The talc used in this formula should be of type HS-58, with the following main component requirements: SiO2 ≥ 58%, MgO ≥ 29%, Al2O3 ≤ 1.5%, CaO ≤ 1.5%, and Fe2O3 ≤ 1.5%. In this formula, the appropriate proportion of talc powder should be controlled at 12-14%.

[0012] Furthermore, the talc powder is designated as HS-58.

[0013] Furthermore, the K₂SiF₆ content in potassium fluorosilicate is above 98%. Potassium fluorosilicate is an inorganic compound with the chemical formula K₂SiF₆, a white crystalline powder that is almost insoluble in cold water. In this formulation, potassium fluorosilicate of type KSF-98 should be selected, with the K₂SiF₆ content controlled above 98%, and the appropriate addition ratio is 5-7%.

[0014] Furthermore, it also includes an adhesive, which is a high-temperature putty.

[0015] Furthermore, the binder constitutes 24-27% of the total mass of the powder.

[0016] Zirconium-rich iron ore is a crucial zirconium ore for steelmaking. It is a complex formed by the high-temperature sintering of metallic zirconium and metallic iron. Zirconium is a rare metal. Zirconium is one of the strongest deoxidizers in steelmaking. Zirconium iron is used as a deoxidizer and alloying additive in special-purpose high-temperature alloys, low-alloy high-strength steels, ultra-high-strength steels, and cast iron, and subsequently in atomic technology, aerospace manufacturing, and radio technology. During flux sintering, zirconium iron partially converts into ZrO2, and the remaining elemental Zr plays a deoxidizing role in the weld during arc combustion. ZrO2 is an acidic oxide in the flux, primarily enhancing the fluidity of molten iron, allowing the weld bead to spread out and optimize its shape. In this invention, zirconium-rich iron ore accounts for 5-7% of the total weight.

[0017] Rare earth silicon-iron alloys can refine grains, and their appropriate addition can improve the secondary crystallization morphology after welding. The silicon-iron alloy in the flux mainly serves a deoxidizing function, while also introducing a certain amount of silicon into the weld. Appropriate amounts of silicon in the weld can improve the strength of the deposited metal. Simultaneously, adding appropriate amounts of silicon to the flux can enhance the fluidity of the molten iron and reduce defects such as cratering and porosity in the weld. Rare earth elements, as additives in the flux, mainly function to further refine acicular ferrite grains and reduce the diffusible hydrogen content of the deposited metal. However, if too many rare earth elements are added, they can easily contaminate grain boundaries, failing to inhibit the formation of proeutectoid ferrite and reducing the impact toughness of the weld. This invention selects a silicon-iron alloy containing the rare earth element Ce, designated ReSiFe-26Ce, with a mass fraction of 2.5-4% in the total weight.

[0018] Nickel-iron carbide is an alloy powder produced by pretreatment of nickel ore, followed by pyrometallurgical refining, and finally high-temperature calcination with coke. Compared to ordinary nickel powder, nickel-iron carbide can improve the transition efficiency and stability of nickel. Nickel can refine the grain, especially in the post-weld acicular ferrite region and recrystallization region, which have a significant impact on low-temperature impact toughness. The addition of an appropriate amount of nickel can improve the stability of low-temperature impact toughness. Simultaneously, to improve weld strength, some carbon needs to be transferred from the flux. Through extensive experimentation, in this invention, the amount of nickel-iron carbide added should be controlled at 2-4%.

[0019] The following describes the roles of each chemical component in the above-mentioned mineral powder in the flux.

[0020] The addition of alumina ensures slag removal during welding. Alumina has a high melting point and low density, allowing it to float to the top of the molten pool during welding, dominating slag shell formation and giving the flux excellent slag removal properties. In this formulation, Al2O3 mainly comes from calcined slag and pre-melted calcium aluminate.

[0021] The main function of silica in welding flux is slag formation. During welding, silica reacts with other components in the flux to form silicates, adjusting the viscosity of the weld slag and reducing the basicity of the flux. An appropriate silica content in the flux ensures proper fluidity of the molten iron during welding, resulting in a smooth weld slag surface and good slag removal. However, excessive silicates can increase weld burn-off. In this formulation, SiO2 mainly comes from calcined sapphire and talc.

[0022] Calcium oxide is a slag-forming agent that increases the basicity of the flux and deoxidizes and desulfurizes the weld metal. If the calcium oxide content in the flux is too low, it cannot effectively purify the weld metal; if the calcium oxide content is too high, it can easily cause coarser weld lines and worsen welding processability. Furthermore, excessive CaO content makes the flux more susceptible to moisture absorption, leading to defects such as cratering and porosity during welding. In this formulation, the CaO mainly comes from pre-melted calcium aluminate.

[0023] Magnesium oxide primarily functions as a slag-forming agent in welding flux. In this invention, magnesium oxide mainly comes from talc. Magnesium oxide can lower the temperature required for the welding slag to reach a molten state. However, excessive magnesium oxide content in the flux can lead to welding defects, thereby reducing weld strength; excessive magnesium oxide content can also worsen the slag-removing properties of the flux, but these can generally be avoided by adjusting the amount of magnesium oxide added.

[0024] One of the highlights of this application is the addition of potassium fluorosilicate. During high-temperature arc combustion, an appropriate amount of potassium ions can stabilize the arc, while an appropriate amount of silicate can reduce flux alkalinity, enhance molten iron fluidity, and optimize weld surface formation. Appropriate amounts of fluoride ions can react with oxides during welding and possess a certain reducing property, reducing potential inclusions in the weld and causing them to float to the slag shell, generating fluorides and elemental metals. Furthermore, fluorides are one of the most effective components for preventing hydrogen porosity in the weld.

[0025] Another highlight of this application is the inclusion of zirconium-rich iron ore. The zirconium in zirconium-rich iron ore combines with oxygen under the high-temperature combustion of an electric arc to form ZrO2. This is an acidic oxide that effectively improves weld bead formation, resulting in a smoother and more even weld surface. To ensure the stability and mechanical properties of multi-wire high-heat welding, most multi-wire submerged arc welding fluxes use fluorine-alkali slag systems, which can lead to a deterioration in the welding processability of multi-wire submerged arc welding. Therefore, it is necessary to appropriately add acidic oxides to balance the flux alkalinity and adjust the welding processability. Previously, ZrO2 was mostly used in surfacing fluxes to improve slag fluidity. In this invention, ZrO2 is innovatively applied to joining welding fluxes to optimize the welding processability of multi-wire welding, representing a new application of an old raw material.

[0026] The binder of this invention uses high-temperature mortar. Adding an appropriate amount of high-temperature mortar can bind the flux powder and granulate it. Furthermore, the moisture in the high-temperature mortar evaporates rapidly after the flux granulation is complete, resulting in round, dense flux particles with high strength that are not easily broken during transportation. The high-temperature mortar is made of inorganic materials and will not release harmful organic compounds during use. It also does not contain heavy metals such as lead, chromium, and cadmium, meeting the strict national requirements for hazardous substance emissions during industrial production. However, excessive binder addition can worsen welding processability and make flux preparation difficult, leading to large particles and poor flux granulation. Through multiple experiments, the amount of high-temperature mortar added should be controlled at 24-27% of the total mass of the mixed powder, and can be flexibly adjusted according to the actual granulation situation during production.

[0027] The preparation method of the above-mentioned high-speed submerged arc welding flux for pipeline circumferential welds includes the following steps: the high-speed submerged arc welding flux powder is first dry-mixed, a high-temperature mortar binder is used as the binder, the sintering temperature is 490-510℃, and the sintering time is more than 2.5h.

[0028] Compared with existing technologies, the fine wire high-speed submerged arc welding flux for pipeline circumferential welds and its preparation method described in this invention have the following advantages: This invention utilizes a fluorine-alkali slag system primarily composed of calcium fluoride, magnesium oxide, aluminum oxide, silicon dioxide, and calcium oxide. Alumina and calcium oxide primarily function as slag-forming agents, improving weld bead slag removal. Calcium fluoride also possesses reducing properties, stabilizing the arc in the flux. The addition of potassium fluorosilicate stabilizes the arc and enhances the fluidity of molten iron during welding, while also possessing reducing properties, thus purifying the weld. The addition of zirconium-rich iron ore adjusts the flux's pH, optimizing weld bead formation. Furthermore, a ferrosilicon alloy containing rare earth elements is added to this main slag system, introducing silicon into the weld. Silicon refines grains and expands the recrystallized fine-grained region, thereby increasing weld strength. The addition of nickel-iron carbide alloy enhances the low-temperature impact toughness of the weld. Through the combined effects of these raw materials, the required strength and low-temperature impact toughness of the butt metal in multi-wire submerged arc welding can be guaranteed.

[0029] Fluoro-alkali slag systems can effectively improve the transition coefficient of the aforementioned alloying elements into the weld. However, excessive alkalinity can lead to decreased welding processability, coarser weld lines, and defects such as porosity and indentation. In such cases, acidic components such as silica and zirconium dioxide are used to neutralize the alkaline slag system of the flux itself, improving the fluidity of the molten metal during welding, optimizing welding processability, and achieving a balance between welding processability and the mechanical properties of the deposited metal. This invention can meet the requirements of multi-wire submerged arc welding of X90Q pipeline circumferential welds, exhibiting good welding processability and post-weld butt metal mechanical properties. It is widely used in the pipeline manufacturing industry, greatly improving people's productivity and quality of life. Detailed Implementation

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0031] The invention will now be described in detail with reference to the embodiments.

[0032] Examples 1-3: The weight percentages of various raw materials in the flux powder are shown in the table below: (%) Table 1. Weight percentage of various raw materials in flux powder (2) The adhesive is high-temperature putty, model GJF-1.

[0033] (3) The sintered flux was prepared according to the above composition and tested. According to the national standard GB / T8110-2020, the welding wire drawn from the wire rod with the composition code ER49-1 and the specification Φ2.0 was used to test the mechanical properties of the butt metal.

[0034] Welding specifications: The first welding wire is powered by DC reverse polarity, and the second to fourth welding wires are powered by AC. The total welding heat input is 25-30 KJ / cm, and the interpass temperature is controlled at ≤100℃. The test plate thickness is 38mm, using a double V-groove with a 60° bevel angle and a 4-6mm blunt edge.

[0035] Table 2 Current and Voltage Meters ① Flux type: Sintered flux.

[0036] ② Flux S and P content: Table 3. Flux S and P content project S P Guaranteed value ≤0.035 ≤0.040 Example 1 0.028 0.035 Example 2 0.027 0.035 Example 3 0.026 0.036 ③ Chemical composition of the deposited metal Table 4 Chemical composition of deposited metal project S P Guaranteed value ≤0.015 ≤0.025 Example 1 0.010 0.022 Example 2 0.008 0.022 Example 3 0.011 0.019 ④ Measured values ​​of mechanical properties of the butt metal (welded state) Table 5. Measured Mechanical Properties of Butt Metals Mechanics Project <![CDATA[R m (MPa)]]> Plate pulling test results Bending test results <![CDATA[KV2(J)-40℃]]> Standard value 695~915 The weld fracture strength is higher than that of the base metal. qualified ≥60 Example 1 752 Broken base material Forward and reverse side bends passed 114、123、118 Example 2 784 Broken base material Forward and reverse side bends passed 92、89、88 Example 3 767 Broken base material Forward and reverse side bends passed 89、92、88 ⑤ The diffusible hydrogen content of the deposited metal is ≤5mL / 100g (mercury method or chromatographic method).

[0037] The above embodiments demonstrate stable arc welding, good molten metal fluidity, and suitability for circumferential welds on pipelines. They exhibit good slag removal properties, allow for continuous welding, and automatically remove slag. The tensile strength of the butt weld is higher than that of the base metal, meeting technical requirements. The plates are bendable on both sides without cracks. The low-temperature impact toughness is qualified and stable.

[0038] Comparative Example 1: Reduce Fluorite The weight percentages of various raw materials in the flux powder are shown in the table below: (%) Table 6. Raw Material Weight Percentage Measured mechanical properties of butt metals (welded condition, welding specifications as per example). Table 7. Measured Mechanical Properties of Butt Metals Mechanics Project <![CDATA[R m (MPa)]]> Plate pulling test results Bending test results <![CDATA[KV2(J)-40℃]]> Standard value 695~915 The weld fracture strength is higher than that of the base metal. qualified ≥60 Measured value 633 Broken weld Straight bends are unacceptable; reverse bends and side bends are unacceptable. 55、58、62 A low fluorite content can lead to unstable arcs during welding, poor weld bead formation, and coarser weld lines. It also increases impurities and harmful element content in the weld, resulting in inclusions in the weld metal and substandard impact toughness.

[0039] Comparative Example 2: Reducing the amount of calcined gemstones The weight percentages of various raw materials in the flux powder are shown in the table below: (%) Table 8. Raw Material Weight Percentage Table Measured mechanical properties of butt metals (welded state) Table 9. Measured Mechanical Properties of Butt Metals Mechanics Project <![CDATA[R m (MPa)]]> Plate pulling test results Bending test results <![CDATA[KV2(J)-40℃]]> Standard value 695~915 The weld fracture strength is higher than that of the base metal. qualified ≥60 Measured value 599 Broken weld Front and back side bends failed to meet standards 43、35、40 The weld was coarse, with slag adhesion, resulting in an unattractive appearance and poor slag removal. The weld failed X-ray inspection, exhibiting multiple slag inclusions. The tensile test bar contained hydrogen pores, and its overall mechanical properties were poor; therefore, it should be discarded.

[0040] Comparative Example 3: Adding pre-melted calcium aluminate The weight percentages of various raw materials in the flux powder are shown in the table below: (%) Table 10 Raw Material Weight Percentage Table Measured mechanical properties of butt metals (welded state) Table 11 Measured Mechanical Properties of Butt Metals Mechanics Project <![CDATA[R m (MPa)]]> Plate pulling test results Bending test results <![CDATA[KV2(J)-40℃]]> Standard value 695~915 The weld fracture strength is higher than that of the base metal. qualified ≥60 Measured value 432 Broken weld Forward and reverse bends failed, side bends passed. 26、32、22 The measured mechanical properties show that when too much pre-melted calcium aluminate is added, slag adhesion defects easily occur in the weld, leading to unqualified X-ray inspection results. The tensile and bending tests also fail; furthermore, the impact toughness is low and does not meet the requirements.

[0041] Comparative Example 4: Reducing Heavy Rare Earth Ferrosilicon The weight percentages of various raw materials in the flux powder are shown in the table below: (%) Table 12 Weight Percentage of Various Raw Materials Measured mechanical properties of butt metals (welded state) Table 13 Measured Mechanical Properties of Butt Metals Mechanics Project <![CDATA[R m (MPa)]]> Plate pulling test results Bending test results <![CDATA[KV2(J)-40℃]]> Standard value 695~915 The weld fracture strength is higher than that of the base metal. qualified ≥60 Measured value 589 Broken weld Forward and reverse side bends passed 88、94、89 The measured mechanical properties of the weld indicate that the molten iron has poor fluidity, resulting in poor weld formation, unevenness, and poor spread of the weld bead when welding the circumferential weld seam of the pipeline. The weld strength is low, the tensile strength is substandard, and although the impact toughness is acceptable, it still does not meet the required mechanical properties.

[0042] Comparative Example 5: Increase the amount of zirconium-rich iron ore The weight percentages of various raw materials in the flux powder are shown in the table below: (%) Table 14 Weight Percentage of Various Raw Materials Measured mechanical properties of butt metals (welded state) Table 15 Measured Mechanical Properties of Butt Metals Mechanics Project <![CDATA[R m (MPa)]]> Plate pulling test results Bending test results <![CDATA[KV2(J)-40℃]]> Standard value 695~915 The weld fracture strength is higher than that of the base metal. qualified ≥60 Measured value 432 Broken weld Forward and reverse bends passed, side bends failed. 50、49、45 During welding, the welding process was poor: the molten iron was too thin, causing it to flow erratically when welding the circumferential weld of the pipeline at position 1G. Numerous indentations and porosity were observed in the weld bead, resulting in poor weld quality. X-ray inspection revealed numerous incomplete fusion defects. Mechanical properties of the butt metal showed a significant decrease in weld strength and low-temperature impact toughness, making it difficult to meet mechanical performance requirements.

[0043] Comparative Example 6: Adding heavy rare earth silicon iron The weight percentage of raw materials is shown in the table below: (%) Table 16 Raw Material Weight Percentage Table Measured mechanical properties of butt metals (welded state) Table 17 Measured Mechanical Properties of Butt Metals Mechanics Project <![CDATA[R m (MPa)]]> Plate pulling test results Bending test results <![CDATA[KV2(J)-40℃]]> Standard value 695~915 The weld fracture strength is higher than that of the base metal. qualified ≥60 Measured value 872 Broken base material Forward and reverse bending and side bending qualified 62、58、53 As can be seen from the mechanical properties of the weld metal, excessive increase in weld strength will lead to a decrease in low-temperature impact toughness, with some values ​​falling below the lower limit of acceptance, thus failing to meet the required mechanical properties.

[0044] Comparative Example 7: Adding pre-melted calcium aluminate The weight percentages of various raw materials in the flux powder are shown in the table below: (%) Table 18 Weight Percentage of Various Raw Materials in Flux Powder Measured mechanical properties of deposited metal (welded state) Table 17 Measured Mechanical Properties of Deposited Metal Mechanics Project <![CDATA[R m (MPa)]]> Plate pulling test results Bending test results <![CDATA[KV2(J)-40℃]]> Standard value 695~915 The weld fracture strength is higher than that of the base metal. qualified ≥60 Measured value 603 Broken base material Front and back side bends failed to meet standards 28、32、25 During welding, the weld bead bulges, making slag removal difficult and requiring manual slag removal, which affects the efficiency of automated welding. Fine slag adheres to the weld bead and is difficult to completely remove. The mechanical properties of the butt metals are poor, with weld strength, low-temperature impact toughness, and other comprehensive mechanical properties failing to meet requirements.

[0045] Comparative Example 8: Reduction of potassium fluorosilicate (1) The weight percentage of various raw materials in the flux powder is shown in the table below: (%) Table 19 Raw Material Weight Percentage Table (2) Measured values ​​of mechanical properties of the deposited metal (in the weld state) Table 20 Measured Mechanical Properties of Deposited Metal Mechanics Project <![CDATA[R m (MPa)]]> Plate pulling test results Bending test results <![CDATA[KV2(J)-40℃]]> Standard value 695~915 The weld fracture strength is higher than that of the base metal. qualified ≥60 Measured value 875 Broken base material Forward and reverse side bends passed 42、107、34 During welding, the multi-wire welding arc is unstable, and sparks appear in the molten pool, affecting the welding working environment. The molten iron is relatively thick, causing the weld to not spread properly during circumferential welding, resulting in coarse weld lines and poor weld formation. The mechanical properties of the butt metal show that while the weld strength is high, the low-temperature impact toughness is unstable, with many low values, leading to poor overall mechanical properties that do not meet the technical requirements.

[0046] Conclusion: The sintered flux in this invention, combined with ER49-1 and using a multi-wire high-speed submerged arc welding process, is specifically designed for X90Q pipeline steel ring welds. It exhibits excellent welding performance and produces aesthetically pleasing weld formations. Tensile strength is guaranteed to be 695~915MPa, yield strength 625~775MPa, and low-temperature impact energy at -40℃ ≥60J, thus solving the problems associated with multi-wire high-speed submerged arc welding of X90Q ring welds. Its excellent comprehensive mechanical properties meet the technical requirements for X90Q pipeline submerged arc welding in applications such as gas pipelines and oil pipelines.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-speed submerged arc welding flux with fine wire for pipeline circumferential welds, characterized in that: By weight percentage, it includes: fluorite 23-26%, calcined charcoal 20-23%, pre-melted calcium aluminate 18-21%, talc 12-14%, potassium fluorosilicate 5-7%, zirconium-rich iron ore 5-7%, heavy rare earth ferrosilicon 2.5-4%, and nickel-iron carbide alloy 2-4%.

2. The fine wire high-speed submerged arc welding flux for pipeline circumferential welds according to claim 1, characterized in that: The calcined char gemstone contains SiO2 ≥ 40% and Al2O3 ≥ 42%. Preferably, the calcined char gemstone is of type NHNT-1.

3. The fine wire high-speed submerged arc welding flux for pipeline circumferential welds according to claim 1, characterized in that: In pre-melted calcium aluminate, CaO accounts for 60-65% and Al2O3 accounts for 25-30%.

4. The fine wire high-speed submerged arc welding flux for pipeline circumferential welds according to claim 1, characterized in that: The pre-melted calcium aluminate is CaAl-30.

5. The fine wire high-speed submerged arc welding flux for pipeline circumferential welds according to claim 1, characterized in that: The talc contains SiO2 ≥ 58%, MgO ≥ 29%, Al2O3 ≤ 1.5%, CaO ≤ 1.5%, and Fe2O3 ≤ 1.5%.

6. The fine wire high-speed submerged arc welding flux for pipeline circumferential welds according to claim 1, characterized in that: The talc powder is designated as HS-58.

7. The fine wire high-speed submerged arc welding flux for pipeline circumferential welds according to claim 1, characterized in that: The K2SiF6 content in potassium fluorosilicate is over 98%.

8. The fine wire high-speed submerged arc welding flux for pipeline circumferential welds according to claim 1, characterized in that: It also includes an adhesive, which is a high-temperature putty.

9. The fine wire high-speed submerged arc welding flux for pipeline circumferential welds according to claim 8, characterized in that: The binder accounts for 24-27% of the total mass of the powder.

10. A method for preparing a fine wire high-speed submerged arc welding flux for pipeline circumferential welds according to any one of claims 1-9, characterized in that: The process includes the following steps: the high-speed submerged arc welding flux powder is first dry-mixed, a high-temperature adhesive is used as the binder, the sintering temperature is 490-510℃, and the sintering time is more than 2.5 hours.

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