Low-hydrogen high-toughness sintered flux and production process thereof

Abstract

The invention discloses a low-hydrogen high-toughness sintered flux and a production process thereof, and relates to the technical field of welding auxiliary materials, and the production process comprises the following steps: proportioning a rare earth reinforced functionalized flux modifier, manganese oxide, magnesium oxide, titanium dioxide and calcium carbonate to obtain a mixture; carrying out ball milling on the mixture, then adding a sodium silicate solution as a binder, and carrying out granulation to obtain a granular semi-finished product; sintering is conducted on the granular semi-finished product, specifically, standing defoaming and dewatering are conducted at the preheating temperature, then heating is conducted to the sintering temperature in a gradient temperature rising mode, sintering heat preservation is conducted, and a sintered product is formed; and the sintered product is subjected to gradient cooling, and the low-hydrogen high-toughness sintered flux is obtained. Through chemical synthesis of the functional modifier and optimization of the production process, low hydrogen and high toughness of the welding flux are synergistically realized. The product can significantly reduce the hydrogen content of the weld joint to avoid cracks, and greatly improve the toughness of the slag to ensure the mechanical properties of the joint, and has excellent comprehensive performance.

Description

Technical Field

[0001] The invention relates to the technical field of welding auxiliary materials, and in particular to a low-hydrogen high-toughness sintered flux and a production process thereof. Background Art

[0002] Sintered flux is an essential auxiliary material for efficient welding methods such as submerged arc welding (SAAW). During the welding process, the flux melts under the high temperature of the arc, forming a slag and a specific atmosphere covering the surface of the molten metal. This slag and atmosphere play multiple critical roles, including protecting the weld pool from harmful atmospheric gases (such as nitrogen and oxygen), stabilizing the welding arc, transitioning alloying elements to the weld metal, and influencing weld formation and mechanical properties. Sintered flux is typically produced by mixing various powdered raw materials (such as silicates, oxides, carbonates, and fluorides) in specific proportions. After adding a binder and granulating, the flux is sintered at a specific temperature to induce a solid-phase reaction between the components, and finally crushed and screened to the desired particle size. The flux's chemical composition, basicity, and particle morphology directly determine its processing performance and impact on weld quality. Therefore, developing sintered fluxes with specific properties is crucial for improving welding quality and efficiency.

[0003] Existing sintered flux technology faces significant technical bottlenecks when meeting high-standard welding requirements, particularly when simultaneously pursuing the two core attributes of low hydrogen and high toughness. First, traditional fluxes generally have strong hygroscopic properties. Physically adsorbed water absorbed during storage and use decomposes under the high temperatures of the welding arc, generating large amounts of hydrogen. This hydrogen dissolves in the molten pool and remains in the weld metal, causing delayed cracking and posing a serious threat to the safety of critical structural components such as high-strength steel and pressure vessels. Second, the slag formed after welding lacks toughness and poor stability at high temperatures. This not only affects the weld's coverage and protection, but can also lead to substandard mechanical properties of the welded joint. While various improvements have been attempted, they often compromise one aspect while also focusing on the other. For example, simply increasing the flux's basicity to reduce hydrogen content often compromises slag fluidity and toughness; adding conventional toughening agents can negatively impact dehydrogenation. Simply physically mixing various functional raw materials makes it difficult to generate synergistic effects within the complex welding metallurgical reactions, failing to fundamentally resolve the conflict between low hydrogen and high toughness. Summary of the Invention

[0004] The purpose of the present invention is to provide a low-hydrogen high-toughness sintered flux and a production process thereof, which solves the problems existing in the background technology.

[0005] In order to solve the above technical problems, the present invention provides a production process of a low-hydrogen, high-toughness sintered flux, comprising the following steps: (a) mixing a rare earth enhanced functionalized flux modifier, manganese oxide, magnesium oxide, titanium dioxide, and calcium carbonate to obtain a mixture; (b) ball-milling the mixture, and then adding a sodium silicate solution as a binder to granulate the mixture to obtain a granular semi-finished product; (c) sintering the granular semi-finished product, the sintering comprising: first, standing for degassing and dehydration at a preheating temperature, then heating to a sintering temperature by a gradient heating method and sintering and holding the temperature to form a sintered product; (d) subjecting the sintered product to gradient cooling to obtain a low-hydrogen, high-toughness sintered flux; The preparation method of the rare earth enhanced functionalized flux modifier in step (a) comprises: mixing a fluoride modified aluminosilicate intermediate with a rare earth oxide, and then performing doping and sintering at a high temperature; The preparation method of the fluoride-modified aluminosilicate intermediate comprises: mixing a calcium aluminosilicate basic skeleton with fluoride, and then performing a low-temperature solid-phase reaction at a grafting temperature; The preparation method of the calcium aluminosilicate basic skeleton comprises: reacting sodium silicate, aluminum oxide and calcium oxide at a reaction temperature.

[0006] Preferably, in the ingredients of step (a), by weight, the rare earth enhanced functionalized flux modifier is 35-45 parts, manganese oxide is 8-12 parts, magnesium oxide is 5-8 parts, titanium dioxide is 3-5 parts, and calcium carbonate is 15-20 parts.

[0007] Preferably, in step (b), the ball milling time is 6-8 hours until the material particle size reaches 200-300 mesh; the concentration of the sodium silicate solution is 3-5%; and the diameter of the granular semi-finished product obtained after granulation is 2-3 mm.

[0008] Preferably, in step (c), the preheating temperature is 300°C, the standing degassing and dehydration time is 30 minutes; the sintering temperature is 750-850°C, and the sintering and heat preservation time is 60 minutes.

[0009] Preferably, in step (d), the gradient cooling rate is 5°C / min.

[0010] Preferably, in the preparation of the calcium aluminosilicate basic skeleton, the reaction temperature is 800-900°C.

[0011] Preferably, in the preparation of the fluoride-modified aluminosilicate intermediate, the fluoride is a mixture of calcium fluoride and potassium fluorosilicate, and the grafting temperature is 600-700°C.

[0012] Preferably, in the preparation of the rare earth enhanced functionalized flux modifier, the rare earth oxide is cerium oxide or lanthanum oxide, and its weight accounts for 0.5-2% of the fluoride modified aluminosilicate intermediate; the high temperature doping sintering temperature is 1000-1100°C.

[0013] Also provided is a low-hydrogen high-toughness sintered flux, which is prepared by the above-mentioned production process of the low-hydrogen high-toughness sintered flux.

[0014] Preferably, it is made by sintering raw materials containing the following components: 35-45 parts by weight of a rare earth-enhanced functionalized flux modifier, 8-12 parts by weight of manganese oxide, 5-8 parts by weight of magnesium oxide, 3-5 parts by weight of titanium dioxide, and 15-20 parts by weight of calcium carbonate; Among them, the rare earth enhanced functionalized flux modifier is made by high temperature doping and sintering of fluoride modified aluminosilicate intermediate and rare earth oxide; Among them, the fluoride-modified aluminosilicate intermediate is formed by a low-temperature solid-phase reaction of a calcium aluminosilicate basic skeleton and fluoride.

[0015] Compared with the prior art, the present invention has the following beneficial effects: Through a unique chemical design, it can actively capture and remove hydrogen sources in a stable form in the high-temperature environment of the welding arc, so that the diffusible hydrogen content in the weld metal reaches an extremely low level, enhancing the ability of the weld joint to resist cold cracks, and providing higher safety redundancy and structural integrity for key engineering components such as in-service pressure-bearing equipment and large steel structures, ensuring their long-term service reliability.

[0016] The formed slag can build a strong and stable network skeleton in the molten state, fundamentally improving the impact toughness of the slag itself and providing better physical protection for the welding pool. Thanks to the micro-regulation effect of special elements, the high-temperature stability of the slag is also enhanced, ensuring that the mechanical properties of the weld joint are excellent and stable, especially when performing multi-layer and multi-pass welding, the overall joint quality can be guaranteed to be highly uniform.

[0017] It ensures that various functional components are pre-integrated in a chemically bonded manner, achieves efficient synergy, and avoids performance uncertainty caused by simple physical mixing. Through precise control of key heat treatment links such as sintering and cooling, a final product with highly consistent performance is obtained, showing excellent processability, stable arc combustion, and clean slag removal after welding, which helps to improve the production cycle and yield of automated welding. DETAILED DESCRIPTION Example 1

[0018] This embodiment provides a production process for a low-hydrogen, high-toughness sintered flux. The process first prepares a rare earth-reinforced functionalized flux modifier, and the preparation process is as follows: sodium silicate, aluminum oxide, and calcium oxide are reacted at 800°C to prepare a calcium aluminosilicate basic skeleton; then, the skeleton is subjected to a solid-phase reaction with a mixture of calcium fluoride and potassium fluorosilicate at 600°C to obtain a fluoride-modified aluminosilicate intermediate; finally, the intermediate is mixed with 0.5% by weight of cerium oxide, and the mixture is doped and sintered at 1000°C to obtain a modifier; the final flux production process is as follows: 35 Parts by weight of the above-mentioned modifier, 8 parts by weight of manganese oxide, 5 parts by weight of magnesium oxide, 3 parts by weight of titanium dioxide, and 15 parts by weight of calcium carbonate were mixed; the mixture was ball-milled in a ball mill for 6 hours to a particle size of 200 mesh, and then granulated with a 3% sodium silicate solution to produce a granular semi-finished product with a diameter of 2 mm; the semi-finished product was preheated at 300°C and allowed to stand for 30 minutes for dehydration and degassing, then heated to 750°C and sintered for 60 minutes; and the sintered product was finally gradient-cooled at a rate of 5°C / min to obtain a finished flux; The core performance of the low-hydrogen, high-toughness sintered flux prepared by the production process of this embodiment is effectively improved; when used for circumferential welding of large pressure vessels, its lower diffusible hydrogen content helps prevent the occurrence of hydrogen-induced cracks, ensuring the safety of the equipment in long-term service; the basic impact toughness of the slag provides reliable mechanical performance guarantee for the welded joint, and at the same time, the slag removal performance is good, reducing the post-weld cleaning time. Example 2

[0019] This embodiment provides a production process for a low-hydrogen, high-toughness sintered flux. The process first prepares a rare earth-reinforced functionalized flux modifier, and the preparation process is as follows: first, a calcium aluminosilicate basic skeleton is prepared at 850°C; then, fluoride is grafted at 650°C to obtain a fluoride-modified aluminosilicate intermediate; finally, the intermediate is mixed with 1.2% by weight of cerium oxide, and the mixture is doped and sintered at 1050°C to obtain a modifier; the final flux production process is as follows: 4 0 parts by weight of the above-mentioned modifier, 10 parts by weight of manganese oxide, 6.5 parts by weight of magnesium oxide, 4 parts by weight of titanium dioxide, and 17.5 parts by weight of calcium carbonate were prepared; the mixture was ball-milled for 7 hours to a particle size of 250 mesh, and granulated with a 4% sodium silicate solution to form particles with a diameter of 2.5 mm; the particles were preheated at 300°C for 30 minutes, then heated to 800°C and sintered for 60 minutes; the sintered product was gradient cooled at a rate of 5°C / min; The low-hydrogen, high-toughness sintered flux prepared by the production process of this embodiment has balanced and excellent comprehensive performance; it is particularly suitable for welding operations in high-humidity environments (such as shipyards and offshore platforms). The bonded fluoride groups in the functionalized modifier show good resistance to moisture absorption and passivation, and the low-hydrogen characteristics of the weld remain stable; the high toughness of the slag enables good coverage and protection of the lower weld during multi-layer and multi-pass welding, thereby improving the quality uniformity of the overall weld joint. Example 3

[0020] This embodiment provides a production process for a low-hydrogen, high-toughness sintered flux. The process first prepares a rare earth-reinforced functionalized flux modifier, and the preparation process is as follows: first, a calcium aluminosilicate basic skeleton is prepared at 900°C; then, fluoride is grafted at 700°C; finally, the intermediate is mixed with 2% by weight of lanthanum oxide, and the modifier is prepared by doping and sintering at 1100°C. The final flux production process is as follows: 45 parts by weight of the above modifier, 12 parts by weight of manganese oxide, 8 parts by weight of magnesium oxide, 5 parts by weight of titanium dioxide, and 20 parts by weight of calcium carbonate are added; the mixture is ball-milled for 8 hours to 300 mesh, and granulated with a 5% sodium silicate solution to produce particles with a diameter of 3 mm; the particles are preheated at 300°C for 30 minutes, then heated to 850°C and sintered for 60 minutes; the sintered product is gradient cooled at a rate of 5°C / min; The low-hydrogen, high-toughness sintered flux prepared by the production process of this embodiment has outstanding performance under extreme conditions; the high content of modifier and sufficient sintering reaction enable the slag impact toughness to reach a high level, which is suitable for welding bridge steel structures or engineering machinery components with strict requirements on impact resistance; at the same time, the excellent dehydrogenation ability can effectively deal with potential hydrogen sources introduced due to incomplete pretreatment of the workpiece surface, providing higher redundancy for welding quality. Example 4

[0021] This embodiment provides a production process for a low-hydrogen, high-toughness sintered flux. The process first prepares a rare earth-reinforced functionalized flux modifier, and the preparation process is as follows: first, a calcium aluminosilicate basic skeleton is prepared at 880°C; then, fluoride is grafted at 680°C; finally, the intermediate is mixed with 1.5% by weight of cerium oxide, and the modifier is prepared by doping and sintering at 1080°C. The final flux production process is as follows: 42 parts by weight of the modifier, 9 parts by weight of manganese oxide, 6 parts by weight of magnesium oxide, 3.5 parts by weight of titanium dioxide, and 18 parts by weight of calcium carbonate are added; the mixture is ball-milled for 7.5 hours to a 280 mesh size, and granulated with a 4.5% sodium silicate solution to produce particles with a diameter of 2.8 mm; the particles are preheated at 300°C for 30 minutes, then heated to 820°C for sintering and held at this temperature for 60 minutes; and the sintered product is gradient-cooled at a rate of 5°C / min. The low-hydrogen, high-toughness sintered flux prepared by the production process of this embodiment achieves a good balance between performance and cost; the flux is suitable for large-scale industrial production, such as in pipeline manufacturing and wind turbine tower production lines. Its stable arc and deposition efficiency of over 95% help to improve the production rhythm of automated welding; at the same time, the reliable low-hydrogen and high-toughness indicators ensure that the product meets the industry's high standards for safety and durability. Example 5

[0022] This embodiment provides a production process for a low-hydrogen, high-toughness sintered flux. The process first prepares a rare earth-reinforced functionalized flux modifier. The preparation process is as follows: a calcium aluminosilicate skeleton is prepared at 860°C; fluoride grafting is then performed at 660°C; finally, the intermediate is mixed with 1.2% by weight of yttrium oxide (Y2O3), and the modifier is prepared by doping and sintering at 1060°C. The final flux production process is as follows: 38 parts by weight of the modifier, 11 parts by weight of manganese oxide, 7 parts by weight of magnesium oxide, 4.5 parts by weight of titanium dioxide, and 19 parts by weight of calcium carbonate are added; the mixture is ball-milled for 7 hours to a 250-mesh size, and granulated with a 4% sodium silicate solution to produce particles with a diameter of 2.5 mm; the particles are preheated at 300°C for 30 minutes, then heated to 830°C and sintered for 60 minutes; and the sintered product is gradient-cooled at a rate of 5°C / min. This example verifies the substitutability of core raw materials. The various performance indicators of the low-hydrogen, high-toughness sintered flux prepared by this production process are not significantly different from those of Examples 2 and 4 using cerium oxide, demonstrating the technical feasibility of replacing cerium oxide with yttrium oxide. This provides an alternative solution for coping with market supply fluctuations of specific rare earth raw materials, enhances the supply chain stability of the technical solution of the present invention, and has better cost control potential while ensuring the welding quality of the product in key areas such as nuclear power.

[0023] Comparative Example 1 Conventional sintered flux in the prior art does not contain the functionalized flux modifier described in the present invention in its formula, but is formed by physically mixing and sintering conventional silicates, oxides and a small amount of fluorides.

[0024] Comparative Example 2 This comparative example provides a production process for a sintered flux, the raw material ratio of which is the same as that of Example 2, but the preparation method is different; this process does not prepare a functionalized modifier by chemical bonding in advance, but directly physically mixes raw materials such as sodium silicate, aluminum oxide, calcium oxide, calcium fluoride, potassium fluorosilicate, and cerium oxide with other components such as manganese oxide, magnesium oxide, titanium dioxide, and calcium carbonate, and then performs the same ball milling, granulation, sintering, and cooling steps as in Example 2.

[0025] Comparative Example 3 This comparative example provides a production process for a sintered flux. The raw material ratio is exactly the same as that in Example 2, and a functionalized modifier is also pre-prepared. However, the process parameters are improperly set. Specifically, when preparing the modifier, the fluoride grafting temperature is 550°C, and the rare earth doping sintering temperature is 950°C. After the final flux is sintered, rapid air cooling is used for cooling, and gradient cooling control is not performed.

[0026] Performance testing and result analysis The fluxes prepared in Examples 1-5 and Comparative Examples 1-3 were subjected to submerged arc welding tests under the same welding specifications, and the weld metal and post-weld slag were sampled and tested. The diffusible hydrogen content was tested using the glycerol displacement method, and the slag impact toughness was tested using the Charpy impact test. The test results are shown in the following table: Table 1 Performance comparison of each embodiment and comparative example Test Number Diffusible hydrogen content (ml / 100g) Slag impact toughness (J / cm²) Slag removal rate (%) Remark Example 1 2.8 25.5 96 By using the lower limit of the parameters of the present invention, the performance has been significantly improved Example 2 2.1 28.2 98 The optimized parameters of the present invention are used to achieve the best overall performance Example 3 2.3 27.5 97 The upper limit of the parameters of the present invention is adopted, and the toughness performance is outstanding Example 4 2.2 27.8 98 Optimized parameter combination, excellent performance Example 5 2.2 27.9 98 Using alternative rare earth raw materials, the performance remains stable Comparative Example 1 7.8 17.5 92 Existing technology, high hydrogen content, insufficient toughness Comparative Example 2 6.5 20.1 93 Physical mixing, no synergistic effect, limited performance improvement Comparative Example 3 5.8 21.3 94 Improper process parameters, insufficient reaction, and substandard performance From the comparison results in Table 1, we can clearly see that: Compared with Comparative Example 1 (prior art), the fluxes prepared in Examples 1-5 of the present invention have a diffusible hydrogen content reduced by more than 60% and a slag impact toughness increased by more than 40%, with significant effects. Compared with Comparative Example 2 (physical mixing), the examples of the present invention achieve synergistic effects among the components by pre-chemically synthesizing the functionalized modifier. The performance is far superior to that of simple physical mixing, demonstrating the necessity and superiority of the core concept of "integrating different functional groups through chemical bonding" in the technical solution of the present invention. Compared with Comparative Example 3 (inappropriate process parameters), the embodiments of the present invention strictly control the various process parameters within the required range, ensuring the full progress of the chemical reaction and the stability of the microstructure of the final product, proving that the process parameter range described in the present invention is critical and effective for achieving the expected technical effects.

[0027] In summary, the low-hydrogen, high-toughness sintered flux and its production process provided by the present invention successfully solve the problem of balancing low hydrogen and high toughness in the existing technology through the design of functional modifiers and precise control of production process parameters. The product has excellent performance and high industrial practical value.

[0028] The above are merely preferred embodiments of the present invention and do not limit the present invention in any other form. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A production process for low-hydrogen high-toughness sintered flux, characterized in that: The following steps are involved: (a) mixing a rare earth enhanced functionalized flux modifier, manganese oxide, magnesium oxide, titanium dioxide, and calcium carbonate to obtain a mixture; (b) ball-milling the mixture, and then adding a sodium silicate solution as a binder to granulate the mixture to obtain a granular semi-finished product; (c) sintering the granular semi-finished product, the sintering comprising: first, standing for degassing and dehydration at a preheating temperature, then heating to a sintering temperature by a gradient heating method and sintering and holding the temperature to form a sintered product; (d) subjecting the sintered product to gradient cooling to obtain a low-hydrogen, high-toughness sintered flux; The preparation method of the rare earth enhanced functionalized flux modifier in step (a) comprises: mixing a fluoride modified aluminosilicate intermediate with a rare earth oxide, and then performing doping and sintering at a high temperature; The preparation method of the fluoride-modified aluminosilicate intermediate comprises: mixing a calcium aluminosilicate basic skeleton with fluoride, and then performing a low-temperature solid-phase reaction at a grafting temperature; The preparation method of the calcium aluminosilicate basic skeleton comprises: reacting sodium silicate, aluminum oxide and calcium oxide at a reaction temperature.

2. The production process of a low-hydrogen high-toughness sintered flux according to claim 1, characterized in that: In the ingredients of step (a), by weight, the rare earth enhanced functionalized flux modifier is 35-45 parts, manganese oxide is 8-12 parts, magnesium oxide is 5-8 parts, titanium dioxide is 3-5 parts, and calcium carbonate is 15-20 parts.

3. The production process of a low-hydrogen high-toughness sintered flux according to claim 1, characterized in that: In step (b), the ball milling time is 6-8 hours until the material particle size reaches 200-300 mesh; the concentration of the sodium silicate solution is 3-5%; and the diameter of the granular semi-finished product obtained after granulation is 2-3 mm.

4. The production process of a low-hydrogen high-toughness sintered flux according to claim 1, characterized in that: In step (c), the preheating temperature is 300°C, the standing degassing and dehydration time is 30 minutes; the sintering temperature is 750-850°C, and the sintering and heat preservation time is 60 minutes.

5. The production process of a low-hydrogen high-toughness sintered flux according to claim 1, characterized in that: In step (d), the gradient cooling rate is 5°C / min.

6. The production process of a low-hydrogen, high-toughness sintered flux according to claim 1, characterized in that: In the preparation of the calcium aluminosilicate basic skeleton, the reaction temperature is 800-900°C.

7. The production process of a low-hydrogen high-toughness sintered flux according to claim 1, characterized in that: In the preparation of the fluoride-modified aluminosilicate intermediate, the fluoride is a mixture of calcium fluoride and potassium fluorosilicate, and the grafting temperature is 600-700°C.

8. The production process of a low-hydrogen, high-toughness sintered flux according to claim 1, characterized in that: In the preparation of the rare earth-enhanced functionalized flux modifier, the rare earth oxide is cerium oxide or lanthanum oxide, and its weight accounts for 0.5-2% of the fluoride-modified aluminosilicate intermediate; the high-temperature doping and sintering temperature is 1000-1100°C.

9. A low-hydrogen, high-toughness sintered flux, characterized in that: The low-hydrogen high-toughness sintered flux is prepared by the production process of any one of claims 1 to 8.

10. A low-hydrogen, high-toughness sintered flux according to claim 9, characterized in that: Made by sintering raw materials containing the following components: 35-45 parts by weight of a rare earth-enhanced functionalized flux modifier, 8-12 parts by weight of manganese oxide, 5-8 parts by weight of magnesium oxide, 3-5 parts by weight of titanium dioxide, and 15-20 parts by weight of calcium carbonate; Among them, the rare earth enhanced functionalized flux modifier is made by high temperature doping and sintering of fluoride modified aluminosilicate intermediate and rare earth oxide; Among them, the fluoride-modified aluminosilicate intermediate is formed by a low-temperature solid-phase reaction of a calcium aluminosilicate basic skeleton and fluoride.