A fluorosilicon manganese iron type sintered welding flux, its preparation method and application

Abstract

The present invention relates to the technical field of welding fluxes, and in particular, to a fluorosiliconmanganese-iron type sintered welding flux, a preparation method thereof and an application thereof. The fluorosiliconmanganese-iron type sintered welding flux is composed of the following components by mass percentage: 36% - 45% of CaF2, 11% - 20% of SiO2, 31% - 42% of MnO, 3% - 8% of Fe2O3, and 4% - 7% of Na2O. When using the fluorosiliconmanganese-iron type sintered welding flux for welding, not only does the weld obtained after welding have good low-temperature toughness and slag detachment performance, but also has excellent arc stability and weld bead formability. The welding process is stable, the weld metal composition and structure obtained after welding are uniform, the surface morphology is good, and there are no defects such as pores and cracks. The present invention further provides a preparation method and an application of the fluorosiliconmanganese-iron type sintered welding flux.

Description

Technical Field

[0001] The present invention relates to the technical field of welding fluxes, and in particular, to a fluorosiliconmanganese-iron type sintered welding flux, a preparation method thereof, and an application thereof. Background Art

[0002] For submerged arc welding, except for the welding wire, the mechanical properties and good processability of the weld zone are mainly determined by the welding flux. The welding flux is one of the main consumables in submerged arc welding and plays important roles such as stabilizing the arc, providing mechanical protection, controlling the weld formation, and alloy transition during the welding process. The composition of the welding flux determines the welding processability and chemical metallurgical properties, and thus affects the structure and mechanical properties of the welded joint. Welding fluxes mainly include agglomerated fluxes, fused fluxes, and sintered fluxes. Among them, sintered fluxes are a kind of high-quality, high-efficiency, energy-saving, and environmentally friendly welding fluxes. Sintered fluxes have no smoke, no arc, and no spatter during welding, and have the advantages of no environmental pollution, low energy consumption, and full utilization of raw materials during the production and manufacturing process.

[0003] However, in the prior art, the sintered welding flux contains various oxides, which will decompose to form free oxygen and oxygen during the welding process. Gases such as oxygen and CO formed by the decarburization reaction cannot be discharged in time in the weld, which will cause pores to form. The free oxygen will increase the brittleness of the weld metal, resulting in defects such as pores and cracks in the weld metal. At the same time, with the increase in brittleness, the mechanical properties of the weld will decline.

[0004] Moreover, due to the fact that the sintered welding flux contains various oxides, during the welding process, the arc has a strong stirring and thermal effect on the flux slag and the weld metal molten pool, causing the transfer of alloying elements between the flux slag and the weld metal molten pool. The composition and structure of the slag formed after welding are somewhat different from those of the original welding flux. This results in a large amount of submerged arc sintered welding fluxes becoming disposable consumables, and the slag formed after welding cannot be reused, which causes waste of resources and is also not conducive to environmental protection.

[0005] Therefore, it is of great significance to provide a sintered welding flux with excellent performance and recyclability.

[0006] In view of this, the present invention is specifically proposed. Summary of the Invention

[0007] The first object of the present invention is to provide a fluorosiliconmanganese-iron type sintered welding flux. By adding a certain content of Fe2O3 and cooperating with specific amounts of CaF2, SiO2, MnO, and Na2O, not only does the weld obtained after welding have good low-temperature toughness and slag removal performance, but also has excellent arc stability and weld formation. The welding process is stable, the composition and structure of the weld metal obtained after welding are uniform, the surface morphology is good, and there are no defects such as pores and cracks.

[0008] The second object of the present invention is to provide a preparation method of a fluorosilicon manganese iron type sintered flux. By using this method, a sintered flux with excellent performance can be obtained, and this method has the advantages of simple operation and suitability for mass production, etc.

[0009] The third object of the present invention is to provide an application of a fluorosilicon manganese iron type sintered flux in welding HSLA steel.

[0010] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0011] The present invention first provides a fluorosilicon manganese iron type sintered flux, which is composed of the following components by mass percentage: 36% - 45% of CaF2, 11% - 20% of SiO2, 31% - 42% of MnO, 3% - 8% of Fe2O3, and 4% - 7% of Na2O.

[0012] Furthermore, the low-temperature impact energy of the welded joint obtained by welding HSLA steel with the fluorosilicon manganese iron type sintered flux is ≥41 J at -40°C.

[0013] Furthermore, the content of acicular ferrite in the welded joint obtained by welding HSLA steel with the fluorosilicon manganese iron type sintered flux is 15% - 32%.

[0014] The present invention further provides a preparation method of a fluorosilicon manganese iron type sintered flux, including the following steps: After uniformly mixing CaF2, SiO2, MnO, and Fe2O3, add water glass thereto and granulate to obtain mixed material particles; the mixed material particles are sintered after drying to obtain the fluorosilicon manganese iron type sintered flux.

[0015] Furthermore, the molecular formula of the water glass is Na2O·nSiO2, where n is the modulus and n = 2.8.

[0016] Furthermore, the water content of the water glass is 45% - 55%.

[0017] Furthermore, the particle size of the mixed material particles is 20 mesh - 50 mesh.

[0018] Furthermore, the sintering temperature is 700°C - 900°C.

[0019] Furthermore, the sintering holding time is 2 h - 4 h.

[0020] The present invention also provides an application of the fluorosilicon manganese iron type sintered flux in welding HSLA steel, and the welding method is submerged arc welding.

[0021] Furthermore, the welding line energy is 57 kJ / cm - 63 kJ / cm.

[0022] Furthermore, the welding speed is 480 mm / min to 520 mm / min.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) The fluorosilicon manganese iron type sintered welding flux provided by the present invention, by adding a certain content of Fe2O3 and synergistically acting with a specific amount of CaF2, SiO2, MnO and Na2O, not only enables the obtained weld seam after welding to have good low-temperature toughness and slag removal performance, but also has excellent arc stability and weld bead formability. The welding process is stable, the metal composition and structure of the obtained weld seam after welding are uniform, the surface morphology is good, and there are no defects such as pores and cracks.

[0025] (2) The fluorosilicon manganese iron type sintered welding flux provided by the present invention, by adding a certain content of Fe2O3, on the one hand, makes the oxygen content of the weld metal more reasonable and can ensure that the weld has excellent mechanical properties. On the other hand, it is beneficial to the oxidation of C, thereby enhancing the decarburization effect of the recycled welding flux and also enabling the recovery and utilization of Fe t O in the welding slag. It can not only avoid waste of resources and energy, but also reduce production and processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required to be used in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 It is the macroscopic morphology diagram of the weld seam obtained after welding in Example 5 provided by the present invention;

[0028] Figure 2 It is the macroscopic fracture morphology diagram of the weld seam obtained after welding in Example 5 provided by the present invention;

[0029] Figure 3 For Figure 2 The enlarged view within the dashed box;

[0030] Figure 4 It is the picture of the welded joint after welding in Example 5 provided by the present invention;

[0031] Figure 5 It is the picture of the welded joint after slag removal in Example 5 provided by the present invention;

[0032] Figure 6 It is the picture of the slag shell peeled off in Example 5 provided by the present invention;

[0033] Figure 7 Macrograph of the weld seam obtained after welding in Comparative Example 1 provided by the present invention;

[0034] Figure 8 Macrograph of the fracture surface of the weld seam obtained after welding in Comparative Example 1 provided by the present invention;

[0035] Figure 9 is Figure 8 Enlarged view within the dashed box;

[0036] Figure 10 Picture of the welded joint after slag removal in Comparative Example 1 provided by the present invention. Specific Embodiments

[0037] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0038] If there is no special explanation, in the present invention, "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc. are only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "the first", "the second", "the third", "the fourth", etc. only serve the purpose of non-exhaustive enumerative description and should be understood not to constitute a closed limitation on quantity.

[0039] If there is no special explanation, "including" and "comprising" mentioned in the present invention mean open-ended or can also be closed-ended. For example, "including" and "comprising" can mean that other components not listed can also be included or comprised, or it can only include or comprise the listed components.

[0040] If there is no special explanation, in the present invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. Among them, "several" refers to any two or any two or more.

[0041] In a first aspect, the present invention provides a fluorosilicon manganese iron type sintered welding flux, which is composed of the following components by mass percentage: 36% - 45% CaF₂, 11% - 20% SiO₂, 31% - 42% MnO, 3% - 8% Fe₂O₃, and 4% - 7% Na₂O.

[0042] In the prior art, too little oxygen content in the weld seam can lead to difficulty in forming fine and dispersed inclusions in the weld seam. This is because oxygen is one of the essential elements for the nucleation of inclusions in the weld seam. Too few inclusions result in the main structure in the weld seam being harmful structures such as polygonal ferrite, grain boundary ferrite, and side plate ferrite. These structures are formed under excessive heat input, where heat accumulates in the weld seam, causing the formation of such coarse structures, which is not conducive to the improvement of the strength and toughness of the welded joint. Moreover, too high oxygen content will lead to defects such as pores and cracks inside the weld seam, and at the same time, greatly increase the brittleness of the weld seam, easily resulting in the sudden fracture of the structural member. Therefore, strict control of the oxygen content is of great significance.

[0043] The fluorosilicon manganese iron type sintered welding flux provided by the present invention contains Fe₂O₃. Therefore, during the welding process, it will provide an oxygen potential, making the oxygen content in the weld metal more reasonable, controlled at about 500 ppm. It also plays a role in decarburization, and at the same time promotes the formation of inclusions with a size below 2 microns, dispersed in the weld seam and pinned at the grain boundaries and inside the austenite grains.

[0044] At the same time, MnO can improve the deposition efficiency of welding. MnO has good electrical conductivity and thus has a certain arc stabilizing performance. MnO will decompose under the action of the arc plasma, release O₂, and promote the oxygen increase in the molten droplet and molten pool. At the same time, it can promote each other with Fe₂O₃ to improve the reaction activity. The addition of MnO in the welding flux will reduce the loss of Mn element in the molten pool, or realize the alloying of Mn element in the weld metal by the flux - molten pool reaction.

[0045] SiO₂ can form a network structure in the slag after welding. This structure can promote the slag removal performance after welding, and at the same time play a role in reasonably controlling Si in the weld seam, and improve the tensile strength, hardness of the welded joint, and hardenability during the solidification of the molten pool.

[0046] The main function of CaF₂ is to increase the alkalinity of the welding flux, reduce the oxygen potential of the welding flux and the oxygen content of the weld metal, optimize the physical and chemical properties of the molten slag, especially the control of high - temperature viscosity and surface tension, optimize the weld formability, and improve the tensile strength and low - temperature toughness of the weld. In addition, CaF₂ can also reduce the melting point of the sintered welding flux. The addition of CaF₂ can reduce the melting point of the sintered welding flux to about 1400 °C, thus greatly optimizing the heating conditions.

[0047] Fe2O3 is the key control component for realizing the recycling of the welding flux, which is used to regulate the Fe-O balance between the welding flux slag and the molten metal pool during the welding process. Adding a certain content of Fe2O3 to the welding flux can, on the one hand, provide oxygen potential during the welding process, making the oxygen content in the weld metal more reasonable, and on the other hand, ensure that the weld has excellent mechanical properties.

[0048] During welding, the molten pool is divided into three regions, namely the droplet region, the hot region, and the cold region. Slag-metal reactions will occur in the droplet region and the hot region respectively. Iron oxide will decompose at high temperature to produce oxygen, increasing the oxygen partial pressure to supply oxygen to the molten pool. Another part of manganese oxide will decompose into manganese and oxygen. Based on the technology of oxide metallurgy, by reasonably controlling the manganese and oxygen content in the weld, the addition of Mn in the weld will increase the volume fraction of acicular ferrite structure in the weld metal, and the grain size of the secondary phase transformation structure in the weld metal will also be refined, solving the problem that due to excessive heat input in large heat input, heat accumulation occurs in the molten pool, resulting in coarse weld structure and poor mechanical properties.

[0049] It can be seen that the sintered welding flux provided by the present invention with specific components and specific ratios is a sintered welding flux with stable welding process, high mechanical properties of the weld metal, uniform weld metal composition and structure, good surface morphology, and excellent slag detachment performance. It has good welding effect when used for welding HSLA steel, and the obtained weld has good low-temperature toughness and slag detachment performance, without defects such as pores and cracks.

[0050] In addition, adding a certain content of Fe2O3 to this fluorosilicon manganese iron type sintered welding flux can recycle the welding flux, which can not only avoid waste of resources and energy, but also reduce production and processing costs.

[0051] In the fluorosilicon manganese iron type sintered welding flux provided by the present invention, the mass percentage content of CaF2 can also be selected as 37%, 38%, 39%, 41%, 42%, 43% or 44%; the mass percentage content of SiO2 can also be selected as 12%, 13%, 14%, 15%, 16%, 17%, 18% or 19%; the mass percentage content of MnO can also be selected as 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or 41%; the mass percentage content of Fe2O3 can also be selected as 4%, 5%, 6% or 7%; the mass percentage content of Na2O can also be selected as 5% or 6%.

[0052] Adopting specific ratios is beneficial to further improving the low-temperature toughness, slag detachment performance, arc stability and weld forming performance of the welded joint, and is beneficial to further improving the uniformity of the weld metal composition and structure.

[0053] In some specific embodiments, the weld joint obtained by welding HSLA steel with the fluorosilico-manganese-ferrite type sintered flux has a low-temperature impact energy of ≥41 J at -40°C.

[0054] Among them, HSLA steel refers to high-strength low-alloy structural steel, also known as "microalloyed steel", which belongs to a kind of steel for offshore engineering.

[0055] The weld joint obtained by welding HSLA steel with the fluorosilico-manganese-ferrite type sintered flux provided by the present invention has good low-temperature toughness.

[0056] In some specific embodiments, the low-temperature impact energy of the weld joint obtained by welding HSLA steel with the fluorosilico-manganese-ferrite type sintered flux at -40°C is 41 J to 50 J, including but not limited to any point value among 42 J, 43 J, 44 J, 45 J, 46 J, 47 J, 48 J, 49 J or the range value between any two of them.

[0057] In some specific embodiments, the content of acicular ferrite in the weld joint obtained by welding HSLA steel with the fluorosilico-manganese-ferrite type sintered flux is 15% to 32%, including but not limited to any point value among 16%, 17%, 18%, 19%, 20%, 22%, 23%, 25%, 27%, 28%, 30%, 31% or the range value between any two of them.

[0058] For the fluorosilico-manganese-ferrite type sintered flux provided by the present invention, it can be seen by metallographic microscope that the content of excellent structures such as acicular ferrite in the weld metal can be as high as 32%.

[0059] In the second aspect, the present invention provides a preparation method of a fluorosilico-manganese-ferrite type sintered flux, including the following steps: After uniformly mixing CaF2 powder, SiO2 powder, MnO powder and Fe2O3 powder, add water glass thereto and granulate to obtain mixed material particles. After drying the mixed material particles, sinter them, and cool to obtain the fluorosilico-manganese-ferrite type sintered flux.

[0060] Among them, water glass is an aqueous solution of sodium silicate. Water glass mainly acts as a binder, and adding water glass can introduce Na2O into the sintered flux, and Na2O can improve the welding stability during the welding process.

[0061] The preparation method of the fluorosilico-manganese-ferrite type sintered flux provided by the present invention can obtain a sintered flux with more excellent performance, improve the low-temperature toughness and slag removal performance of the weld, as well as the uniformity and surface morphology of the weld metal, and there are no defects such as pores and cracks.

[0062] Moreover, this preparation method has the advantages of simple operation and being suitable for mass production.

[0063] In some specific embodiments, the water glass has a molecular formula of Na2O·nSiO2, where n is the modulus, n = SiO2 / Na2O (molar ratio). The modulus shows the composition of the water glass and is an important parameter of the water glass. Here, n = 2.8.

[0064] In some specific embodiments, the water content of the water glass is 45% - 55%, and values such as 48%, 50%, or 52% can also be selected.

[0065] In some specific embodiments, the particle size of the mixed material particles is 20 mesh - 50 mesh, including but not limited to any point value among 25 mesh, 30 mesh, 35 mesh, 40 mesh, 45 mesh or the range value between any two of them.

[0066] It can be understood that during the granulation process, particles with a particle size greater than 50 mesh are crushed, and particles with a particle size less than 20 mesh are re - granulated until the particle size of all particles is 20 - 50 mesh, thus obtaining the mixed material particles.

[0067] In some specific embodiments, the sintering temperature is 700°C - 900°C, including but not limited to any point value among 720°C, 740°C, 760°C, 780°C, 800°C, 820°C, 840°C, 860°C, 880°C or the range value between any two of them.

[0068] In some specific embodiments, the sintering holding time is 2h - 4h, including but not limited to any point value among 2.5h, 3h, 3.5h or the range value between any two of them.

[0069] Adopting the above - mentioned sintering temperature and sintering time is beneficial to further improving the low - temperature toughness and slag - removing performance of the welded joint, as well as the uniformity and surface morphology of the weld metal.

[0070] In some specific embodiments, the sintering device includes a corundum crucible.

[0071] In some specific embodiments, after sintering, there is also a sieving step. The particle size of the obtained manganese - fluorosilicate - type sintered welding flux after sieving is 20 mesh - 50 mesh.

[0072] In some specific embodiments, the mixing time is 50min - 60min, including but not limited to any point value among 52min, 54min, 56min, 58min or the range value between any two of them.

[0073] In some specific embodiments, the mixing is carried out in a V - type mixer. Among them, the frequency of the V - type mixer can be 0.5Hz.

[0074] In some specific embodiments, the granulation is carried out in an XH433 PS type granulator.

[0075] In some specific embodiments, the drying temperature is 250°C to 350°C, including but not limited to any point value among 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, 320°C, 330°C, 340°C or the range value between any two of them.

[0076] In some specific embodiments, the drying time is 2h to 4h, including but not limited to any point value among 2.5h, 3h, 3.5h or the range value between any two of them.

[0077] In some specific embodiments, the drying method includes drying in an oven, and the drying is carried out in a tube furnace or an oven.

[0078] Adopting the above preparation parameters is beneficial to obtaining a sintered welding flux with more excellent performance.

[0079] In a third aspect, the present invention provides an application of a fluorosilicon manganese iron type sintered welding flux in welding HSLA steel, and the welding method is submerged arc welding.

[0080] That is, by using the submerged arc welding method and a fluorosilicon manganese iron type sintered welding flux, HSLA steel is welded. Among them, the fluorosilicon manganese iron type sintered welding flux is dried before welding.

[0081] The sintered welding flux with excellent performance provided by the present invention can meet the welding process with HSLA steel as the base material. Using this sintered welding flux for welding HSLA steel is more beneficial to improving the low-temperature toughness, slag detachment performance, arc stability and weld formation of the welded joint, as well as the uniformity of the weld metal composition and structure.

[0082] In some specific embodiments, the welding line energy is 57 kJ / cm to 63 kJ / cm, including but not limited to any point value among 58 kJ / cm, 59 kJ / cm, 60 kJ / cm, 61 kJ / cm, 62 kJ / cm or the range value between any two of them.

[0083] The specific parameters in the welding process are important means to control and improve the welding performance. By adopting the above welding line energy in the present invention, it is beneficial to improve the low-temperature toughness and slag detachment performance of the weld, and improve the uniformity and morphology of the weld.

[0084] In some specific embodiments, the welding speed is 480 mm / min to 520 mm / min, including but not limited to the point values of any one of 485 mm / min, 490 mm / min, 495 mm / min, 500 mm / min, 505 mm / min, 510 mm / min, 515 mm / min or the range values between any two of them.

[0085] Adopting the above welding speed is beneficial to further improve the low-temperature toughness and slag removal performance of the weld seam, and improve the uniformity and morphology of the weld seam.

[0086] The following will describe the implementation embodiments of the present invention in detail in conjunction with the examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0087] Example 1

[0088] The fluorosilicon manganese iron type sintered flux provided in this example is composed of the following components by mass percentage: 42% CaF2, 20% SiO2, 31% MnO, 3% Fe2O3 and 4% Na2O.

[0089] The preparation method of the fluorosilicon manganese iron type sintered flux provided in this example includes the following steps: Put 483 g of CaF2, 125 g of SiO2, 356.5 g of MnO and 34.5 g of Fe2O3 into a V-type mixer with a frequency of 0.5 Hz and stir evenly. Then add 300 g of water glass (Na2O·nSiO2, the modulus n is 2.8, and the water content is 48%) to it, and mix and stir for 50 min to obtain a mixed material. Place the mixed material in an XH433 PS type granulator for granulation to obtain mixed material particles with a particle size of 20 mesh to 50 mesh (the particle size distribution is within the range of 20 mesh to 50 mesh); Place the mixed material particles in a tubular furnace and dry them at 350 °C for 2 h. Then place the dried mixed material particles in a muffle furnace and sinter them at 700 °C for 2 h to obtain the fluorosilicon manganese iron type sintered flux.

[0090] Place the fluorosilicon manganese iron type sintered flux prepared in Example 1 in a drying oven at 300 °C and dry it for 2 h. Then use the submerged arc welding method to weld the HSLA steel with the dried sintered flux. The welding parameters are as follows: the welding line energy is 60 kJ / cm, and the welding speed is 500 mm / min.

[0091] Example 2

[0092] The fluorosilicon manganese iron type sintered flux provided by this embodiment is composed of the following components by mass percentage: 41% CaF₂, 18% SiO₂, 33% MnO, 4% Fe₂O₃, and 4% Na₂O.

[0093] The preparation method of the fluorosilicon manganese iron type sintered flux provided by this embodiment includes the following steps: Put 471.5 g of CaF₂, 102 g of SiO₂, 379.5 g of MnO, and 46 g of Fe₂O₃ into a V-type mixer with a frequency of 0.5 Hz and stir evenly. Then add 300 g of water glass (Na₂O·nSiO₂, modulus n is 2.8, water content is 48%) to it, and mix and stir for 50 min to obtain a mixed material. Place the mixed material in an XH433 PS type granulator for granulation to obtain mixed material particles with a particle size of 20 - 50 mesh; Place the mixed material particles in a tube furnace and dry at 350 °C for 2 h, then place the dried mixed material particles in a muffle furnace and sinter at 700 °C for 2 h to obtain the fluorosilicon manganese iron type sintered flux.

[0094] Place the fluorosilicon manganese iron type sintered flux prepared in Example 2 in a drying oven at 350 °C and dry for 2 h. Then, using the submerged arc welding method, weld HSLA steel with the dried sintered flux. The welding parameters are as follows: the welding line energy is 57 kJ / cm, and the welding speed is 480 mm / min.

[0095] Example 3

[0096] The fluorosilicon manganese iron type sintered flux provided by this embodiment is composed of the following components by mass percentage: 40% CaF₂, 16% SiO₂, 35% MnO, 4% Fe₂O₃, and 5% Na₂O.

[0097] The preparation method of the fluorosilicon manganese iron type sintered flux provided by this embodiment includes the following steps: Put 460 g of CaF₂, 70 g of SiO₂, 402.5 g of MnO, and 46 g of Fe₂O₃ into a V-type mixer with a frequency of 0.5 Hz and stir evenly. Then add 300 g of water glass (Na₂O·nSiO₂, modulus n is 2.8, water content is 52%) to it, and mix and stir for 50 min to obtain a mixed material. Place the mixed material in an XH433 PS type granulator for granulation to obtain mixed material particles with a particle size of 20 - 50 mesh; Place the mixed material particles in a tube furnace and dry at 350 °C for 2 h, then place the dried mixed material particles in a muffle furnace and sinter at 700 °C for 2 h to obtain the fluorosilicon manganese iron type sintered flux.

[0098] The fluorosilico - manganese - iron type sintered flux prepared in Example 3 was placed in a drying oven at a temperature of 330 °C and dried for 2.5 h. Then, the submerged arc welding method was used to weld HSLA steel with the dried sintered flux. The welding parameters were as follows: the welding line energy was 63 kJ / cm, and the welding speed was 520 mm / min.

[0099] Example 4

[0100] The fluorosilico - manganese - iron type sintered flux provided in this example consists of the following components by mass percentage: 39% CaF2, 14% SiO2, 37% MnO, 4% Fe2O3, and 6% Na2O.

[0101] The preparation method of the fluorosilico - manganese - iron type sintered flux provided in this example includes the following steps: 448.5 g of CaF2, 47 g of SiO2, 425.5 g of MnO, and 46 g of Fe2O3 were put into a V - type mixer with a frequency of 0.5 Hz and stirred evenly. Then, 300 g of water glass (Na2O·nSiO2, modulus n was 2.8, water content was 52%) was added thereto, and the mixture was stirred for 50 min to obtain a mixed material. The mixed material was granulated in an XH433 PS type granulator to obtain mixed - material particles with a particle size of 20 - 50 mesh; the mixed - material particles were placed in a tubular furnace and dried at 350 °C for 2 h, and then the dried mixed - material particles were placed in a muffle furnace and sintered at 700 °C for 2 h to obtain the fluorosilico - manganese - iron type sintered flux.

[0102] The fluorosilico - manganese - iron type sintered flux prepared in Example 4 was placed in a drying oven at a temperature of 290 °C and dried for 3.5 h. Then, the submerged arc welding method was used to weld HSLA steel with the dried sintered flux. The welding parameters were as follows: the welding line energy was 58 kJ / cm, and the welding speed was 490 mm / min.

[0103] Example 5

[0104] The fluorosilico - manganese - iron type sintered flux provided in this example consists of the following components by mass percentage: 38% CaF2, 12% SiO2, 40% MnO, 5% Fe2O3, and 5% Na2O.

[0105] The preparation method of the fluorosilico-manganese-ferrite type sintered welding flux provided by this embodiment includes the following steps: Put 437 g of CaF2, 28 g of SiO2, 460 g of MnO, and 57.5 g of Fe2O3 into a V-type mixer with a frequency of 0.5 Hz and stir evenly. Then add 300 g of water glass (Na2O·nSiO2, modulus n is 2.8, water content is 50%) to it, and mix and stir for 50 min to obtain a mixed material. Place the mixed material in an XH433 PS type granulator for granulation to obtain mixed material particles with a particle size of 20 - 50 mesh; Place the mixed material particles in a tube furnace and dry them at 350 °C for 2 h. Then place the dried mixed material particles in a muffle furnace and sinter them at 700 °C for 2 h to obtain the fluorosilico-manganese-ferrite type sintered welding flux.

[0106] Place the fluorosilico-manganese-ferrite type sintered welding flux prepared in Example 5 in a drying oven at 350 °C and dry it for 2 h. Then use the submerged arc welding method to weld HSLA steel with this dried sintered welding flux. The welding parameters are as follows: The welding line energy is 60 kJ / cm, and the welding speed is 500 mm / min.

[0107] The macroscopic morphology of the weld after welding in this embodiment is as Figure 1 shown. From Figure 1 it can be seen that after welding, the weld composition is uniform, the surface morphology is good, and the slag detachment property is good.

[0108] The macroscopic fracture morphology of the weld after welding in this embodiment is as Figure 2 shown. Figure 3 It is Figure 2 the enlarged view within the dashed box, that is, the microscopic fracture morphology diagram. From Figure 2 and Figure 3 it can be seen that the impact fracture morphology of the weld is ductile fracture, and the dimple diameter is small, the density is large, which can absorb a large amount of energy released during fracture, and can effectively avoid sudden fracture during use and avoid the occurrence of various accidents.

[0109] Thus, it can be seen that by adding a certain content of Fe2O3 and cooperating with CaF2, SiO2, MnO, and Na2O, the present invention has excellent arc stability and weld forming property, the welding process is stable, the weld metal composition and structure after welding are uniform, the surface morphology is good, and there are no defects such as pores and cracks.

[0110] Example 6

[0111] The fluorosilico-manganese-ferrite type sintered welding flux provided by this embodiment is composed of the following components by mass percentage: 37% of CaF2, 13% of SiO2, 40% of MnO, 6% of Fe2O3, and 4% of Na2O.

[0112] The preparation method of the sintered welding flux provided in this example is basically the same as that in Example 5, except that: the mass of the raw materials is replaced with 425.5 g of CaF2, 39.5 g of SiO2, 460 g of MnO and 69 g of Fe2O3 (the mass of water glass remains unchanged), and the sintering temperature in this example is 840 °C.

[0113] Using the fluorosilicon manganese iron type sintered welding flux prepared in this example to weld HSLA steel, the welding method is exactly the same as that in Example 5.

[0114] Example 7

[0115] The fluorosilicon manganese iron type sintered welding flux provided in this example is composed of the following components by mass percentage: 36% of CaF2, 11% of SiO2, 41% of MnO, 7% of Fe2O3 and 5% of Na2O.

[0116] The preparation method of the sintered welding flux provided in this example is basically the same as that in Example 5, except that: the mass of the raw materials is replaced with 414 g of CaF2, 16.5 g of SiO2, 471.5 g of MnO and 80.5 g of Fe2O3 (the mass of water glass remains unchanged), and the sintering temperature in this example is 880 °C.

[0117] Using the fluorosilicon manganese iron type sintered welding flux prepared in this example to weld HSLA steel, the welding method is exactly the same as that in Example 5.

[0118] Example 8

[0119] The fluorosilicon manganese iron type sintered welding flux provided in this example is composed of the following components by mass percentage: 36% of CaF2, 11% of SiO2, 38% of MnO, 8% of Fe2O3 and 7% of Na2O.

[0120] The preparation method of the sintered welding flux provided in this example is basically the same as that in Example 5, except that: the mass of the raw materials is replaced with 414 g of CaF2, 16.5 g of SiO2, 437 g of MnO and 92 g of Fe2O3 (the mass of water glass remains unchanged), and the sintering temperature in this example is 900 °C.

[0121] Using the fluorosilicon manganese iron type sintered welding flux prepared in this example to weld HSLA steel, the welding method is exactly the same as that in Example 5.

[0122] Comparative Example 1

[0123] The sintered welding flux provided in this comparative example is composed of the following components by mass percentage: 38% of CaF2, 32% of SiO2, 20% of MnO, 5% of Fe2O3 and 5% of Na2O.

[0124] The preparation method of the sintered flux provided in this comparative example is basically the same as that in Example 5, with the only difference being that the masses of the raw materials are replaced with 437 g of CaF2, 258 g of SiO2, 230 g of MnO, and 57.5 g of Fe2O3 (the mass of the water glass remains unchanged).

[0125] Using the sintered flux prepared in this comparative example, HSLA steel was welded, and the welding method was exactly the same as that in Example 5.

[0126] Comparative Example 2

[0127] The sintered flux provided in this comparative example is composed of the following components by mass percentage: 38% CaF2, 22% SiO2, 30% MnO, 5% Fe2O3, and 5% Na2O.

[0128] The preparation method of the sintered flux provided in this comparative example is basically the same as that in Example 5, with the only difference being that the masses of the raw materials are replaced with 437 g of CaF2, 143 g of SiO2, 345 g of MnO, and 57.5 g of Fe2O3 (the mass of the water glass remains unchanged).

[0129] Using the sintered flux prepared in this comparative example, HSLA steel was welded, and the welding method was exactly the same as that in Example 5.

[0130] Comparative Example 3

[0131] The sintered flux provided in this comparative example is composed of the following components by mass percentage: 54% CaF2, 11% SiO2, 20% MnO, 8% Fe2O3, and 7% Na2O.

[0132] The preparation method of the sintered flux provided in this comparative example is basically the same as that in Example 5, with the only difference being that the masses of the raw materials are replaced with 621 g of CaF2, 16.5 g of SiO2, 230 g of MnO, and 92 g of Fe2O3 (the mass of the water glass remains unchanged).

[0133] Using the sintered flux prepared in this comparative example, HSLA steel was welded, and the welding method was exactly the same as that in Example 5.

[0134] Comparative Example 4

[0135] The sintered flux provided in this comparative example is composed of the following components by mass percentage: 43% CaF2, 12% SiO2, 40% MnO, and 5% Na2O.

[0136] The preparation method of the sintered flux provided in this comparative example is basically the same as that in Example 5, with the only difference being that Fe2O3 was not added and the mass of CaF2 was replaced with 494.5 g.

[0137] The sintered welding flux prepared in this comparative example was used to weld HSLA steel, and the welding method was exactly the same as that in Example 5.

[0138] Experimental example

[0139] The welded joints obtained by welding with each example and each comparative example were tested for the content of acicular ferrite, the number density of inclusions, the proportion (number proportion) of inclusions with a diameter less than 2 μm, and the low-temperature impact energy (-40 °C). The results are shown in Table 1 below.

[0140] Among them, the content of acicular ferrite was measured by the intercept method after sampling the welded joint and magnifying it 200 times under an OLYMPUS GX51 metallographic microscope.

[0141] The test method for the number density of inclusions is as follows: The welded joint was sampled and photographed at a magnification of 5000 times using a TESCAN MIRA3 field emission scanning electron microscope for statistics.

[0142] The test of the low-temperature impact energy (-40 °C) was carried out with reference to GB / T 2650-2008, and the instrument used was a SANS-ZBC2452-C impact testing machine.

[0143] Table 1 Performance test results of each group of welded joints

[0144]

[0145] It can be seen from Table 1 that the welded joints obtained in each example have good low-temperature toughness. In particular, the low-temperature impact energy (-40 °C) of the welded joint in Example 5 is 50 J, which is much greater than the national standard of 34 J, and the content of acicular ferrite is 32%. The welded joints obtained in each comparative example have poor low-temperature toughness, less than the national standard of 34 J, and the content of acicular ferrite ≤ 13%.

[0146] Furthermore, pictures of the welded joints after welding in Example 5 and Comparative Example 1 were taken respectively, as well as pictures after slag removal respectively. The results are as Figures 4 to 10 shown. Among them, Figure 4 is a picture of the welded joint after welding in Example 5. Figure 5 is a picture of the welded joint in Example 5 after slag removal. Figure 6 is a picture of the slag shell peeled off from Example 5. Figure 7 is a macroscopic morphology diagram of the weld seam after welding in Comparative Example 1. Figure 8 is a macroscopic fracture morphology diagram of the weld seam after welding in Comparative Example 1. Figure 9 is Figure 8 an enlarged view within the dashed box, that is, a microscopic fracture morphology diagram. Figure 10 is a picture of the welded joint in Comparative Example 1 after slag removal.

[0147] From Figure 4 and Figure 5 it can be seen that the weld of Example 5 has no defects and has good slag detachment performance. From Figure 6 it can be seen that the slag shell peeled off from Example 5 has a smooth surface and excellent protection effect on the weld, further indicating its good slag detachment performance.

[0148] From Figure 8 and Figure 9 it can be seen that the impact fracture morphology of the weld of Comparative Example 1 is brittle fracture, with a large number of cleavage planes in the form of river patterns, and the impact performance is poor. From Figure 10 it can be seen that the slag shell adheres to the surface of the welded joint of Comparative Example 1 and cannot be completely detached, that is, the slag detachment performance of Comparative Example 1 is poor.

[0149] Thus, it can be seen that by adding a certain content of Fe2O3 and synergistically acting with CaF2, SiO2 and MnO, and by controlling the manganese and oxygen contents in the weld, the weld has good low-temperature toughness (greater than the national standard of 34 J) and slag detachment performance under the condition of a relatively low content of acicular ferrite.

[0150] Although the present invention has been illustrated and described with specific embodiments, it should be realized that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; those of ordinary skill in the art should understand that: without departing from the spirit and scope of the present invention, the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A fluorine-silicon-manganese-iron type sintered flux, characterized in that: The following components are calculated by weight percentage: Composition: CaF2 36%~45%, SiO2 11%~20%, MnO 31%~42%, Fe2O3 3%~8% and Na2O 4%~7%.

2. The fluorine-silicon-manganese-iron type sintered flux according to claim 1, characterized in that: The low-temperature impact energy of the welded joint obtained by welding HSLA steel with the fluorine-silicon-manganese-iron type sintered flux at -40°C is ≥41J.

3. The fluorine-silicon-manganese-iron type sintered flux according to claim 1, characterized in that: The acicular ferrite content in the welded joint obtained by welding HSLA steel with the fluorine-silicon-manganese-iron type sintered flux is 15%-32%.

4. A method for preparing the fluorine-silicon-manganese-iron type sintered flux according to any one of claims 1 to 3, characterized in that: The steps include: After CaF2, SiO2, MnO and Fe2O3 are uniformly mixed, water glass is added thereto and granulated to obtain mixed material particles; The mixed material particles are dried and then sintered to obtain the fluorine-silicon-manganese-iron type sintered flux.

5. The method for preparing the fluorine-silicon-manganese-iron type sintered flux according to claim 4, characterized in that: The molecular formula of the water glass is Na2O·nSiO2, wherein n is the modulus, n=2.8; and the water content of the water glass is 45%-55%.

6. The method for preparing the fluorine-silicon-manganese-iron type sintered flux according to claim 4, characterized in that: The particle size of the mixed material particles is 20 mesh to 50 mesh.

7. The method for preparing the fluorine-silicon-manganese-iron type sintered flux according to claim 4, characterized in that: The sintering temperature is 700° C. to 900° C., and the sintering holding time is 2 h to 4 h.

8. Use of the fluorine-silicon-manganese-iron type sintered flux according to any one of claims 1 to 3 in welding HSLA steel, characterized in that: The welding method is submerged arc welding.

9. The use of the fluorine-silicon-manganese-iron type sintered flux in welding HSLA steel according to claim 8, characterized in that: The welding line energy is 57kJ / cm~63kJ / cm, and the welding speed is 480mm / min~520mm / min.

Images