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

Abstract

The application discloses a kind of low hydrogen high toughness sintering flux and its production process, it is related to welding auxiliary material technical field, including the functionalization flux modifier of rare earth strengthening, manganese oxide, magnesium oxide, titanium dioxide and calcium carbonate are dosed, and mixed material is obtained;The mixed material is ball milled, then add sodium silicate solution as binder and granulated, and granular semi-finished product is obtained;Sintering is carried out to granular semi-finished product, and sintering includes: first static deaeration and dehydration at preheating temperature, then heated to sintering temperature using gradient heating mode and sintering insulation, form sintered product;Sintered product is gradient cooled, and low hydrogen high toughness sintering flux is obtained.The application realizes the low hydrogen and high toughness of flux by chemical synthesis of functional modifier and optimization of production process.The product can significantly reduce the hydrogen content of weld to avoid crack, while significantly improving the toughness of slag to ensure the mechanical properties of joint, and the comprehensive performance is excellent.

Description

TECHNICAL FIELD

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

[0002] Sintered flux is an indispensable key auxiliary material in high-efficiency welding methods such as submerged arc automatic welding. In the welding process, the flux melts under high temperature of the electric arc to form a molten slag and a certain atmosphere covering the surface of the molten metal. This layer of molten slag and atmosphere plays multiple key roles in protecting the welding pool from the invasion of harmful gases (such as nitrogen and oxygen) in the air, stabilizing the welding arc, transferring alloying elements to the weld metal, and affecting the weld formation and mechanical properties. The production of sintered flux usually involves uniformly mixing various powdered raw materials (such as silicates, oxides, carbonates, and fluorides) in specific proportions, adding a binder to granulate, and then sintering at a certain temperature to cause solid-phase reactions among the components. Finally, the sintered flux is crushed and sieved to the desired particle size. The chemical composition, alkalinity, and particle morphology of the flux directly determine its process performance and impact on weld quality. Therefore, developing sintered flux with specific properties is crucial for improving welding quality and efficiency.

[0003] The existing sintered flux technology has obvious technical bottlenecks when dealing with high-standard welding requirements, especially when pursuing both low hydrogen and high toughness. First, traditional fluxes generally have strong hygroscopicity. The physical adsorbed water absorbed during storage and use decomposes to produce a large amount of hydrogen gas under the high temperature of the welding arc. This hydrogen gas dissolves in the molten pool and remains in the weld metal, becoming the culprit of delayed cracking, posing a serious threat to the safety of key structural components such as high-strength steel and pressure vessels. Second, the molten slag formed after welding has insufficient toughness and poor stability at high temperatures, which not only affects the protective effect on the weld, but also may lead to substandard mechanical properties of the welded joint. Although there have been various improvement attempts in the industry, they have trade-offs. For example, simply increasing the alkalinity of the flux to reduce hydrogen content often sacrifices the fluidity and toughness of the molten slag. Adding conventional toughening agents may adversely affect the dehydrogenation effect. Simply physically mixing various functional raw materials cannot produce a synergistic effect in the complex welding metallurgical reactions, and cannot fundamentally solve the contradiction between low hydrogen and high toughness. SUMMARY

[0004] The present application aims to provide a low-hydrogen high-toughness sintered flux and a production process thereof, solving the problems in the background art.

[0005] To solve the above technical problems, the present application provides a production process for a low-hydrogen high-toughness sintered flux, comprising the following steps:

[0006] (a) dosing the rare earth reinforced functionalized flux modifier, manganese oxide, magnesium oxide, titanium dioxide and calcium carbonate to obtain a mixture;

[0007] (b) ball milling the mixture, and then granulating the mixture by adding sodium silicate solution as a binder to obtain a granular semi-product;

[0008] (c) sintering the granular semi-product, which comprises: firstly, standing and de-aerating and dehydrating at a preheating temperature, and then heating to a sintering temperature by gradient heating and sintering for a sintering holding time to form a sintered product;

[0009] (d) gradient cooling the sintered product to obtain a low-hydrogen high-toughness sintered flux;

[0010] The method for preparing the rare earth reinforced functionalized flux modifier in step (a) comprises: mixing a fluoride-modified aluminosilicate intermediate and a rare earth oxide, and then doping and sintering at a high temperature;

[0011] The method for preparing the fluoride-modified aluminosilicate intermediate comprises: mixing a calcium aluminosilicate basic framework and a fluoride, and then performing a low-temperature solid-phase reaction at a grafting temperature;

[0012] The method for preparing the calcium aluminosilicate basic framework comprises: reacting sodium silicate, aluminum oxide and calcium oxide at a reaction temperature.

[0013] Preferably, in the dosing of step (a), the rare earth reinforced functionalized flux modifier is 35-45 parts by weight, the manganese oxide is 8-12 parts by weight, the magnesium oxide is 5-8 parts by weight, the titanium dioxide is 3-5 parts by weight, and the calcium carbonate is 15-20 parts by weight.

[0014] Preferably, in step (b), the ball milling time is 6-8 hours until the particle size of the material reaches 200-300 mesh; the concentration of the sodium silicate solution is 3-5%; and the diameter of the granular semi-product obtained after granulation is 2-3 mm.

[0015] Preferably, in step (c), the preheating temperature is 300°C, and the standing and de-aerating and dehydrating time is 30 minutes; the sintering temperature is 750-850°C, and the sintering holding time is 60 minutes.

[0016] Preferably, in step (d), the gradient cooling rate is 5°C / min.

[0017] Preferably, in the preparation of the calcium aluminosilicate basic framework, the reaction temperature is 800-900°C.

[0018] 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.

[0019] Preferably, in the preparation of the rare earth reinforced functionalized flux modifier, the rare earth oxide is cerium oxide or lanthanum oxide, and the weight of the rare earth oxide accounts for 0.5-2% of the fluoride modified aluminosilicate intermediate; the temperature of high-temperature doping sintering is 1000-1100°C.

[0020] Also provided is a low-hydrogen high-toughness sintered flux prepared by the production process of the low-hydrogen high-toughness sintered flux.

[0021] Preferably, the low-hydrogen high-toughness sintered flux is prepared by sintering raw materials comprising:

[0022] 35-45 parts by weight of the rare earth reinforced 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;

[0023] Preferably, the rare earth reinforced functionalized flux modifier is prepared by high-temperature doping sintering of a fluoride modified aluminosilicate intermediate and a rare earth oxide;

[0024] Preferably, the fluoride modified aluminosilicate intermediate is prepared by low-temperature solid-phase reaction of a calcium aluminosilicate basic skeleton and fluorine.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] Through unique chemical design, hydrogen sources can be actively captured and removed 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 welded joint to resist cold cracks, providing higher safety redundancy and structural integrity protection for key engineering components such as in-service pressure equipment and large steel structures, and ensuring the reliability of long-term service.

[0027] The formed slag can construct a solid and stable network skeleton in a molten state, fundamentally improving the impact toughness of the slag itself, and providing more superior physical protection for the welding pool. Thanks to the micro-regulation effect of special elements, the high-temperature stability of the slag is also strengthened, ensuring that the mechanical properties of the welded joint are excellent and stable, and especially when multi-layer and multi-pass welding is performed, the overall joint quality can be highly uniform.

[0028] It is ensured that various functional components are pre-integrated in a chemical bond, realizing efficient synergistic effect, avoiding performance uncertainty caused by simple physical mixing, and 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 burning, and clean post-weld slag, which is helpful to improve the production rhythm and yield of automatic welding. DETAILED DESCRIPTION Example 1

[0029] The embodiment provides a production process of 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, sodium silicate, aluminum oxide and calcium oxide are reacted at 800 DEG C to prepare a calcium aluminosilicate basic framework; then, the framework is mixed with a calcium fluoride and potassium fluosilicate mixture to perform solid phase reaction at 600 DEG C to obtain a fluoride modified aluminosilicate intermediate; finally, the intermediate is mixed with 0.5% of cerium oxide by weight, and doping sintering is performed at 1000 DEG C to prepare the modifier; and the production process of the final flux is as follows: 35 parts by weight of the above 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 are mixed; the mixture is ball milled in a ball mill for 6 hours, so that the particle size reaches 200 meshes, and then a 3% sodium silicate solution is added to granulate, so that a granular semi-finished product with a diameter of 2mm is prepared; the semi-finished product is preheated at 300 DEG C and dehydrated and defoamed for 30 minutes, and then heated to 750 DEG C for sintering and heat preservation for 60 minutes; the sintered product is finally gradient cooled at a rate of 5 DEG C / min to obtain the finished flux;

[0030] The low-hydrogen high-toughness sintered flux prepared by the production process of the embodiment has the core performance effectively improved; when used for girth welding of a large pressure vessel, the low diffusible hydrogen content helps to prevent the generation of hydrogen-induced cracks, and the safety of long-term service of the equipment is ensured; the basic impact toughness of the molten slag provides reliable mechanical property guarantee for the welded joint, and meanwhile, the slag removal performance is good, and the post-weld cleaning time is reduced. Embodiment 2

[0031] The embodiment provides a production process of 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, sodium silicate, aluminum oxide and calcium oxide are reacted at 800 DEG C to prepare a calcium aluminosilicate basic framework; then, the framework is mixed with a calcium fluoride and potassium fluosilicate mixture to perform solid phase reaction at 600 DEG C to obtain a fluoride modified aluminosilicate intermediate; finally, the intermediate is mixed with 0.5% of cerium oxide by weight, and doping sintering is performed at 1000 DEG C to prepare the modifier; and the production process of the final flux is as follows: 35 parts by weight of the above 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 are mixed; the mixture is ball milled in a ball mill for 6 hours, so that the particle size reaches 200 meshes, and then a 3% sodium silicate solution is added to granulate, so that a granular semi-finished product with a diameter of 2mm is prepared; the semi-finished product is preheated at 300 DEG C and dehydrated and defoamed for 30 minutes, and then heated to 750 DEG C for sintering and heat preservation for 60 minutes; the sintered product is finally gradient cooled at a rate of 5 DEG C / min to obtain the finished flux;

[0032] The low-hydrogen high-toughness sintered flux prepared by the production process of the embodiment has balanced and excellent comprehensive performance; it is especially suitable for welding operations in high-humidity environments (such as shipyards and offshore platforms), the fluoride groups bonded in the functionalized modifier show good moisture absorption passivation ability, and the low-hydrogen characteristics of the weld remain stable; the high-toughness characteristics of the slag provide good coverage protection for the lower layer of welds when multi-layer multi-pass welding is performed, thereby improving the quality uniformity of the overall welded joint. Example 3

[0033] The embodiment provides a production process of a low-hydrogen high-toughness sintered flux; the process first prepares a rare earth-strengthened functionalized flux modifier, and the preparation process is as follows: first, a calcium aluminosilicate basic framework is prepared at 900°C; then, fluoride grafting is performed at 700°C; finally, the intermediate is mixed with 2% by weight of lanthanum oxide, and doping sintering is performed at 1100°C to obtain the modifier; the final production process of the flux is as follows: 45 parts by weight of the above-mentioned 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 blended; the mixture is ball milled for 8 hours to 300 mesh, granulated with a 5% sodium silicate solution, and particles with a diameter of 3 mm are prepared; the particles are preheated at 300°C for 30 minutes, then heated to 850°C for sintering and kept for 60 minutes; the sintered product is cooled at a rate gradient of 5°C / min;

[0034] The low-hydrogen high-toughness sintered flux prepared by the production process of the embodiment has outstanding performance under extreme conditions; the high content of the modifier and the sufficient sintering reaction enable the slag impact toughness to reach a high level, and the flux is suitable for welding bridge steel structures or engineering machinery parts that have strict requirements on impact performance; at the same time, the excellent dehydrogenation ability can effectively deal with potential hydrogen sources introduced due to incomplete surface pretreatment of the workpiece, thereby providing higher redundancy for the welding quality. Example 4

[0035] The embodiment provides a production process of 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 DEG C; then, fluoride grafting is carried out at 680 DEG C; finally, the intermediate is mixed with 1.5% of cerium oxide by weight, and the modified agent is prepared by doping sintering at 1080 DEG C; and the production process of the final flux is as follows: 42 parts by weight of the modified agent, 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 mixed; the mixture is ball milled for 7.5 hours to 280 meshes, granulated with a sodium silicate solution with a concentration of 4.5%, and particles with a diameter of 2.8 mm are prepared; the particles are preheated at 300 DEG C for 30 minutes, then heated to 820 DEG C for sintering and kept for 60 minutes; and the sintered product is cooled at a rate of 5 DEG C / min;

[0036] The low-hydrogen high-toughness sintered flux prepared by the production process of the embodiment has a good balance between performance and cost; the flux is suitable for large-scale industrial production, for example, on a pipeline manufacturing and wind tower production line, and the stable arc and more than 95% of the deposition efficiency help to improve the production rhythm of automatic welding; meanwhile, the reliable low-hydrogen and high-toughness indexes ensure that the product meets the high standard requirements of the industry on safety and durability. Embodiment 5

[0037] The embodiment provides a production process of 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 DEG C; then, fluoride grafting is carried out at 680 DEG C; finally, the intermediate is mixed with 1.5% of cerium oxide by weight, and the modified agent is prepared by doping sintering at 1080 DEG C; and the production process of the final flux is as follows: 42 parts by weight of the modified agent, 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 mixed; the mixture is ball milled for 7.5 hours to 280 meshes, granulated with a sodium silicate solution with a concentration of 4.5%, and particles with a diameter of 2.8 mm are prepared; the particles are preheated at 300 DEG C for 30 minutes, then heated to 820 DEG C for sintering and kept for 60 minutes; and the sintered product is cooled at a rate of 5 DEG C / min;

[0038] This embodiment verifies the substitutability of the core raw material; the low-hydrogen high-toughness sintered flux prepared by the production process has no significant difference in various performance indicators compared with examples 2 and 4 using cerium oxide, proving the technical feasibility of replacing cerium oxide with yttrium oxide; this provides an alternative solution for coping with fluctuations in the market supply of specific rare earth raw materials, enhancing the supply chain stability of the technical solution of the present application, while ensuring the welding quality of the product for key fields such as nuclear power, and having better cost control potential.

[0039] Comparative example 1

[0040] The conventional sintered flux of the prior art does not contain the functional flux modifier described in the present application in its formula, but is physically mixed and sintered by conventional silicates, oxides and a small amount of fluorides.

[0041] Comparative example 2

[0042] This comparative example provides a production process for sintered flux, which has the same raw material ratio as example 2, but different preparation methods; this process does not prepare functional modifiers by chemical bonding in advance, but physically mixes sodium silicate, aluminum oxide, calcium oxide, calcium fluoride, potassium fluosilicate, cerium oxide and other components with manganese oxide, magnesium oxide, titanium dioxide, calcium carbonate and other components, and then performs the same ball milling, granulation, sintering and cooling processes as example 2.

[0043] Comparative example 3

[0044] This comparative example provides a production process for sintered flux, which has the same raw material ratio as example 2, and also prepares functional modifiers in advance, but the process parameters are not properly set; specifically: when preparing the modifier, the fluorine grafting temperature is 550°C, and the rare earth doping sintering temperature is 950°C; after the final flux sintering is completed, rapid air cooling is used for cooling, without gradient cooling control.

[0045] Performance testing and result analysis

[0046] The fluxes prepared in examples 1-5 and comparative examples 1-3 above 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 by the glycerol displacement method, and the slag impact toughness was tested by the Charpy impact test; the test results are shown in the following table:

[0047] Table 1: Performance comparison of examples and comparative examples

[0048] Test No. Diffusion hydrogen content (ml / 100g) Molten slag impact toughness (J / cm²) Deslagging rate (%) Remarks Example 1 2.8 25.5 96 Using the lower limit of the parameters of the application, the performance has been significantly improved Example 2 2.1 28.2 98 Using the optimized parameters of the application, the overall performance is the best Example 3 2.3 27.5 97 Using the upper limit of the parameters of the application, the toughness performance is outstanding Example 4 2.2 27.8 98 Optimizing the parameter combination, the performance is excellent 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 Prior art, 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, performance does not meet the standard

[0049] From the comparison results in table 1, it can be clearly seen that:

[0050] Compared with the comparative example 1 (prior art), the flux prepared in the inventive examples 1-5 has a diffusion hydrogen content reduced by more than 60% and a slag impact toughness increased by more than 40%, and the effect is remarkable.

[0051] Compared with the comparative example 2 (physical mixing), the inventive examples realize the synergistic effect of the components by pre-chemically synthesizing the functional modifier, and the performance is much better than that of simple physical mixing, proving the necessity and superiority of the core idea of "integrating different functional groups through chemical bonding" in the technical scheme of the present application.

[0052] Compared with the comparative example 3 (improper process parameters), the inventive examples strictly control the process parameters within the required range, ensure the full chemical reaction and the stability of the microstructure of the final product, and prove that the process parameter range described in the present application is key and effective for achieving the expected technical effect.

[0053] In summary, the low-hydrogen high-toughness sintering flux and its production process provided by the present application successfully solve the problem of difficult to balance low hydrogen and high toughness in the prior art through the design of functional modifier and the precise control of production process parameters, and the product has excellent performance and high industrial practical value.

[0054] The above is only a preferred embodiment of the present application, and does not limit the present application in other forms. Any skilled person in the art may modify or change the above disclosed technical content to equivalent embodiments applied to other fields, but any simple modification, equivalent change and modification made according to the technical essence of the present application to the above embodiments without departing from the technical scheme content of the present application still belongs to the protection scope of the present application technical scheme.

Claims

1. A process for producing a low hydrogen high toughness sintering flux, characterized by, The method comprises the following steps: (a) preparing a mixture by mixing a rare earth reinforced functionalized flux modifier, manganese oxide, magnesium oxide, titanium dioxide and calcium carbonate; (b) ball milling the mixture, and then granulating the mixture by adding a sodium silicate solution as a binder to obtain a granular semi-product; (c) sintering the granular semi-product, which comprises the following steps: firstly, standing and deaerating and dehydrating at a preheating temperature, then heating to a sintering temperature by gradient heating and sintering for a sintering holding time to form a sintered product; (d) gradient cooling the sintered product to obtain a low-hydrogen high-toughness sintered flux; The preparation method of the rare earth reinforced functionalized flux modifier in step (a) comprises the following steps: mixing a fluoride modified aluminosilicate intermediate and a rare earth oxide, and then doping and sintering at a high temperature; The preparation method of the fluoride modified aluminosilicate intermediate comprises the following steps: mixing a calcium aluminosilicate basic framework and a fluoride, and then performing a low-temperature solid-phase reaction at a grafting temperature; The preparation method of the calcium aluminosilicate basic framework comprises the following steps: reacting sodium silicate, aluminum oxide and calcium oxide at a reaction temperature.

2. The process for producing a low hydrogen high toughness sintering flux according to claim 1, wherein In the mixing in step (a), the rare earth reinforced functionalized flux modifier is 35-45 parts by weight, the manganese oxide is 8-12 parts by weight, the magnesium oxide is 5-8 parts by weight, the titanium dioxide is 3-5 parts by weight, and the calcium carbonate is 15-20 parts by weight.

3. The process for producing a low hydrogen high toughness sintering flux as claimed in claim 1 wherein, In step (b), the ball milling time is 6-8 hours until the particle size of the material reaches 200-300 mesh; the concentration of the sodium silicate solution is 3-5%; and the diameter of the granular semi-product obtained after granulation is 2-3 mm.

4. The process for producing a low hydrogen high toughness sintering flux as claimed in claim 1 wherein, In step (c), the preheating temperature is 300°C, the standing and deaerating and dehydrating time is 30 minutes, the sintering temperature is 750-850°C, and the sintering holding time is 60 minutes.

5. The process for producing a low hydrogen high toughness sintering flux as claimed in claim 1 wherein, In step (d), the gradient cooling rate is 5°C / min.

6. The process for producing a low hydrogen high toughness sintering flux according to claim 1, wherein In the preparation of the calcium aluminosilicate basic framework, the reaction temperature is 800-900°C.

7. The process for producing a low hydrogen high toughness sintering flux as claimed in claim 1 wherein, 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 process for producing a low hydrogen high toughness sintering flux according to claim 1, wherein In the preparation of the rare earth reinforced functionalized flux modifier, the rare earth oxide is cerium oxide or lanthanum oxide, and the weight of the rare earth oxide accounts for 0.5-2% of the fluoride modified aluminosilicate intermediate; and the doping and sintering temperature at a high temperature is 1000-1100°C.

9. A low hydrogen, high toughness sintering flux characterized by, A low-hydrogen high-toughness sintered flux prepared by the production process of any one of claims 1-8.

10. A low hydrogen, high toughness sintering flux according to claim 9, wherein A low-hydrogen high-toughness sintered flux is prepared by sintering raw materials comprising the following components: 35-45 parts by weight of a rare earth reinforced 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; The rare earth reinforced functionalized flux modifier is prepared by doping and sintering a fluoride modified aluminosilicate intermediate and a rare earth oxide at a high temperature; The fluoride modified aluminosilicate intermediate is prepared by a low-temperature solid-phase reaction of a calcium aluminosilicate basic framework and a fluoride.