Core-shell structure sintered flux and preparation method and application thereof

Abstract

The invention relates to the technical field of welding, in particular to a core-shell structure sintered flux and a preparation method and application thereof. The invention provides a core-shell structure sintered flux. The core-shell structure sintered flux comprises an inner core and an outer shell wrapping the surface of the inner core. The inner core comprises an alloy component and a sintered flux basic component; the housing includes a sintered flux base component. According to the sintered flux with the core-shell structure, transition of alloy elements can be effectively protected, the yield of the alloy elements is remarkably improved, and the technical problem that the content of the alloy elements in transition to weld metal is low due to the fact that the alloy elements added in an existing sintered flux are extremely prone to oxidation and burning loss in the high-temperature sintering and welding process is solved.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a core-shell structure sintering flux, its preparation method, and its application. Background Technology

[0002] Sintered fluxes, as an important branch of high-performance welding materials, demonstrate significant advantages in the field of high heat input welding. These fluxes typically possess high melting points and low bulk density, enabling them to withstand the prolonged high-temperature thermal cycling associated with high heat input welding, thus ensuring welding process stability and weld quality. Furthermore, their basicity can be flexibly adjusted over a wide range, allowing for precise transition of microalloying elements into the weld through formulation design while maintaining excellent process performance, thereby achieving customized control over the weld metal composition and microstructure.

[0003] However, when highly reactive alloy powders such as ferrotitanium and ferroboron are directly added to sintering flux, the alloying elements undergo severe oxidation and burn-off under the combined effects of the high-temperature sintering process during flux preparation and the extreme high-temperature electric arc during welding. This not only results in a low effective yield of expensive alloying additives but also prevents the target alloying elements from transitioning to the weld metal in the predetermined amount, severely affecting the control of weld microstructure and properties.

[0004] Therefore, in sintered flux systems, how to improve the effective transition of alloying elements under high heat input welding conditions and suppress their oxidation loss throughout the sintering and welding process is a core technical problem that urgently needs to be solved in this field. Developing a technical solution that can synergistically ensure good flux process performance and efficient transition of alloying elements is of great significance for promoting the rapid development of flux metallurgy and improving the quality and lifespan of welded structures in major engineering projects.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The primary objective of this invention is to provide a core-shell structure sintering flux that effectively protects the transition of alloying elements and significantly improves their yield. It solves the problem that the alloying elements added to the sintering flux are easily oxidized and burned off during high-temperature sintering and welding, resulting in a low content of these elements transitioning to the weld metal.

[0007] The second objective of this invention is to provide a method for preparing a core-shell structure sintering flux.

[0008] A third objective of this invention is to provide the application of the core-shell structure sintering flux described above in high heat input submerged arc welding.

[0009] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: The present invention provides a core-shell structured sintering flux, comprising a core and a shell covering the surface of the core; The core comprises alloy components and sintered flux base components; The outer shell comprises a sintered flux base component.

[0010] Furthermore, the alloy composition includes iron-titanium alloys and / or ferroborone alloys.

[0011] Furthermore, the titanium content in the iron-titanium alloy is 30wt%~70wt%; And / or, the boron content in the ferroborone alloy is 5wt%~25wt%.

[0012] Furthermore, the basic components of the sintering flux, by mass parts, include: 35-45 parts CaF2, 25-35 parts MgO, and 20-30 parts Al2O3.

[0013] Furthermore, the mass of the alloy component accounts for 0.5% to 3% of the total mass of the core-shell structure sintering flux; And / or, the mass of the outer shell accounts for 10% to 40% of the total mass of the core-shell structure sintering flux.

[0014] This invention also provides a method for preparing the core-shell structure sintering flux as described above, comprising the following steps: S1. Mix the alloy powder and the sintering flux base powder to obtain a core dry mix; mix the core dry mix and the binder to obtain a core wet mix; after the core wet mix is ​​granulated and sieved, a core semi-finished product is obtained. S2. In the granulator, the core semi-finished product is sprayed with atomized binder while rolling, and sintered flux base powder is added to obtain flux green pellets. S3. After sintering the flux green particles, the core-shell structure sintered flux is obtained.

[0015] Further, in step S1, the particle size of the alloy powder is 80-100 mesh; And / or, in steps S1 and S2, the particle size of the sintered flux base powder is 300~400 mesh.

[0016] Furthermore, step S1 includes at least one of the following features (1) to (3); (1) The adhesive includes water glass adhesive; (2) The mass of the binder accounts for 15% to 25% of the total mass of the core dry mix; (3) The particle size of the core semi-finished product is 1~1.4mm.

[0017] Furthermore, it includes at least one of the following features (1) to (3); (1) In step S2, the adhesive includes a water glass solution; (2) In step S2, the particle size of the flux green blank particles is 1~2mm; (3) In step S3, the sintering includes: heating to 650~850℃ and holding for 1.5~3.5h, followed by furnace cooling.

[0018] The present invention also provides the application of the core-shell structure sintering flux as described above in high heat input submerged arc welding.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The core-shell structured sintering flux of the present invention consists of a core and a shell covering the surface of the core; wherein the core is an alloy component and a basic component of the sintering flux, and the shell is a basic component of the sintering flux without alloy components; it can effectively protect the transition of alloying elements and significantly improve their yield, solving the technical problem that the alloying elements added to existing sintering fluxes are easily oxidized and burned off during high-temperature sintering and welding, resulting in a low content of them transitioning to the weld metal. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic flowchart of the preparation method of the core-shell structure sintering flux of the present invention.

[0022] Figure 2 This is a schematic diagram of the macroscopic morphology of the weld metal cross-section of the present invention. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0024] In some embodiments of the present invention, a core-shell structured sintering flux is provided, comprising a core and a shell covering the surface of the core; The core consists of alloy components and sintered flux base components; The outer shell comprises a sintered flux base component.

[0025] The core-shell structured sintering flux of the present invention consists of a core and a shell covering the surface of the core; wherein the core is an alloy component and a basic component of the sintering flux, and the shell is a basic component of the sintering flux without alloy components; it can effectively protect the transition of alloy elements and significantly improve their yield, solving the technical problem that the alloy components (such as ferro-titanium alloy, ferro-boron alloy, etc.) added to existing sintering fluxes are easily oxidized and burned off during high-temperature sintering and welding, resulting in a low content of them transitioning to the weld metal.

[0026] The core-shell structured sintering flux of this invention constructs a crucial physical barrier by encapsulating the active alloy components within an inert flux shell. This dense shell effectively isolates the alloy in the core from contact with oxygen and oxidizing components during flux sintering and the initial stages of welding, significantly reducing pre-oxidation burn-off. During welding, the shell preferentially melts to form a slag coating, further delaying the direct erosion of the core by the high temperature of the arc and the oxidizing atmosphere. This controlled release mechanism allows more alloying elements to transition within the protected molten pool environment, avoiding severe burn-off in the high-temperature zone, thereby significantly improving the transition efficiency and yield to the weld metal.

[0027] In some embodiments of the present invention, the alloy composition includes iron-titanium alloy and / or ferroborone alloy.

[0028] In some embodiments of the present invention, the titanium content in the iron-titanium alloy is 30wt% to 70wt%; typically, but not limitingly, for example, the titanium content in the iron-titanium alloy can be 30wt%, 50wt%, 70wt%, and any value between any two of these.

[0029] In some embodiments of the invention, the boron content in the ferroborone alloy is 5 wt% to 25 wt%; typically, but not limitingly, for example, the boron content in the ferroborone alloy can be 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, and any value between any two of these.

[0030] In some embodiments of the present invention, the basic components of the sintering flux, by mass parts, include: 35-45 parts CaF2, 25-35 parts MgO, and 20-30 parts Al2O3; typically, but not limitingly, for example, the mass parts of CaF2 can be 35 parts, 38 parts, 40 parts, 42 parts, 45 parts, and any value between any two thereof; the mass parts of MgO can be 25 parts, 28 parts, 30 parts, 32 parts, 35 parts, and any value between any two thereof; the mass parts of Al2O3 can be 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, and any value between any two thereof.

[0031] In some embodiments of the invention, the mass of the alloy component accounts for 0.5% to 3% of the total mass of the core-shell structure sintering flux; typically, but not limitingly, for example, the mass of the alloy component accounts for 0.5%, 1%, 1.5%, 2%, 2.5%, 3% of the total mass of the core-shell structure sintering flux, and any value between any two thereof.

[0032] In some embodiments of the invention, the mass of the outer shell accounts for 10% to 40% of the total mass of the core-shell structure sintering flux; typically, but not limitingly, for example, the mass of the outer shell accounts for 10%, 15%, 20%, 25%, 30%, 35%, 40% of the total mass of the core-shell structure sintering flux, and any value between any two thereof.

[0033] See Figure 1 In some embodiments of the present invention, the preparation method of the core-shell structure sintering flux includes the following steps: S1. Mix the alloy powder and the sintering flux base powder to obtain the core dry mix; mix the core dry mix and the binder to obtain the core wet mix; after the core wet mix is ​​granulated (initial granulation) and sieved, the core semi-finished product is obtained. S2. In the granulator, the core semi-finished product is sprayed with atomized binder while rolling, and sintered flux base powder is added to obtain flux green granules. S3. After sintering the flux green particles, a core-shell structure sintered flux is obtained.

[0034] The method for preparing the core-shell structure sintering flux of the present invention involves coating the surface of a mixture of alloy powder and sintering flux base powder with sintering flux base powder under the action of a binder, and then sintering to obtain the core-shell structure sintering flux.

[0035] In some embodiments of the present invention, in step S1, the alloy powder includes iron-titanium alloy powder and / or ferroboron alloy powder; preferably, the titanium content in the iron-titanium alloy powder is 30wt%~70wt%; and the boron content in the ferroboron alloy powder is 5wt%~25wt%.

[0036] In some embodiments of the present invention, in step S1, the particle size of the alloy powder is 80 to 100 mesh; typically, but not limitingly, for example, in step S1, the particle size of the alloy powder can be 80 mesh, 85 mesh, 90 mesh, 95 mesh, 100 mesh, and any value between any two of these.

[0037] In some embodiments of the present invention, in steps S1 and S2, the sintered flux base powder, by mass parts, includes: 35-45 parts of CaF2 powder, 25-35 parts of MgO powder, and 20-30 parts of Al2O3 powder.

[0038] In some embodiments of the present invention, in steps S1 and S2, the particle size of the sintered flux base powder is 300 to 400 mesh; typically, but not limitingly, for example, in steps S1 and S2, the particle size of the sintered flux base powder can be 300 mesh, 320 mesh, 340 mesh, 360 mesh, 380 mesh, 400 mesh, and any value between any two of these.

[0039] In some embodiments of the present invention, in step S1, the binder includes a water glass binder (sodium silicate with a modulus of 2.2 to 2.4).

[0040] In some embodiments of the invention, in step S1, the mass of the binder accounts for 15% to 25% of the total mass of the core dry mix; typically, but not limitingly, for example, in step S1, the mass of the binder accounts for 15%, 17%, 20%, 23%, 25% of the total mass of the core dry mix, and any value between any two thereof.

[0041] In some embodiments of the present invention, in step S1, the raw materials of alloy powder and sintering flux base powder are placed in a V-type mixer and mixed for 60-90 minutes to obtain a core dry mix; the core dry mix and binder are mixed evenly to obtain a core wet mix.

[0042] In some embodiments of the present invention, in step S1, the core wet mixture is placed into a granulator for granulation to form initial particles; the initial particles are screened using a sieve, and initial particles with a particle size of 1~1.4mm are selected as core semi-finished products.

[0043] In some embodiments of the present invention, in step S1, the particle size of the core semi-finished product is 1 to 1.4 mm; typically, but not limitingly, for example, in step S1, the particle size of the core semi-finished product can be 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, and any value between any two of these.

[0044] In some embodiments of the present invention, in step S2, the binder includes a water glass solution; preferably, water glass and water are mixed in a volume ratio of (1~1.5):1 to obtain a water glass solution.

[0045] In some embodiments of the present invention, in step S2, the raw material of the sintering flux base powder is placed in a V-type mixer and mixed for 60-90 minutes to obtain the shell dry mix.

[0046] In some embodiments of the present invention, in step S2, the core semi-finished product is placed in the granulator again. While the core semi-finished product is rolling, atomized binder is sprayed evenly onto the surface of the core semi-finished product. At the same time, the outer shell dry mix is ​​gradually and evenly added. Under the action of the binder, the outer shell dry mix is ​​evenly coated on the surface of the core semi-finished product to obtain flux green pellets (core-shell green pellets). Under the action of the binder, the fine outer shell dry mix adheres to the surface of the core semi-finished product layer by layer. After rolling and agglomeration, flux green pellets with a core-shell structure are finally formed.

[0047] In some embodiments of the present invention, in step S2, the particle size of the flux green particles is 1 to 2 mm; typically, but not limitingly, for example, in step S2, the particle size of the flux green particles can be 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, and any value between any two of these.

[0048] In some embodiments of the present invention, step S3 includes sintering: heating to 650~850°C and holding for 1.5~3.5 hours, followed by furnace cooling; typically, but not limitingly, for example, in step S3, the sintering temperature can be 650°C, 670°C, 690°C, 710°C, 730°C, 750°C, 770°C, 790°C, 810°C, 830°C, 850°C, and any value between any two of these.

[0049] The flux green particles are placed in a sintering furnace for sintering. The sintering process parameters are: heating to 650~850℃ and holding for 1.5~3.5h, followed by cooling to room temperature with the furnace, thereby obtaining a core-shell structured sintered flux product with high mechanical strength and dense structure.

[0050] In some embodiments of the present invention, the application of core-shell structure sintering flux in high heat input submerged arc welding is also provided.

[0051] In some embodiments of the present invention, high heat input submerged arc welding includes: using a high heat input of 60 kJ / cm to perform flat plate welding on ship plate steel; the welding process is as follows: the front wire uses a DC power supply with a welding current of 850A and an arc voltage of 32V; the rear wire uses an AC power supply with a welding current of 625A and an arc voltage of 36V; the welding speed is controlled at 500 mm / min.

[0052] Example 1 The core-shell structure sintered flux provided in this embodiment includes a core and a shell covering the surface of the core; the core includes alloy components and basic components of the sintered flux; the shell includes basic components of the sintered flux. The alloy composition is an iron-titanium alloy with a titanium content of 70 wt%. The basic components of the sintered flux, by mass percentage, include: CaF2 40%, MgO 35%, and Al2O3 25%; The alloy component accounts for 1% of the total mass of the core-shell structure sintering flux, while the outer shell accounts for 20% of the total mass of the core-shell structure sintering flux.

[0053] The method for preparing core-shell structure sintering flux provided in this embodiment includes the following steps: S1. Place 10g of alloy powder raw material (iron-titanium alloy powder, particle size 80-100 mesh) and 790g of sintered flux base powder raw material (CaF2 powder, MgO powder and Al2O3 powder, all particle size 300-400 mesh) in a V-type mixer and mix at a frequency of 0.5Hz for 90 minutes to obtain a core dry mix; mix the core dry mix (mass ratio 1:0.2) and water glass binder (sodium silicate modulus 2.2-2.4) evenly to obtain a core wet mix; place the core wet mix into a disc granulator for granulation to form initial particles; sieve the initial particles using a sieve and select initial particles with a particle size of 1-1.4mm as the core semi-finished product; S2. Place the raw materials of the sintering flux base powder (CaF2 powder, MgO powder and Al2O3 powder, all with a particle size of 300~400 mesh) into a V-type mixer and mix for 90 minutes to obtain the shell dry mix. The core semi-finished product is placed back into the granulator. While the core semi-finished product is rolling, 100ml of atomized water glass solution (water glass and water mixed in a 1:1 volume ratio) is sprayed evenly onto the surface of the core semi-finished product. At the same time, 200g of shell dry mix is ​​gradually and evenly added. The fine shell dry mix is ​​coated onto the surface of the core semi-finished product under the action of the water glass solution (binder), resulting in flux green blank particles with a core-shell structure. The particle size of the flux green blank particles is 1.6~2mm. S3. Place the flux blank particles into a muffle furnace, heat to 800℃ at a rate of 5℃ / min and hold for 2 hours, then cool to room temperature with the furnace to obtain core-shell structure sintered flux.

[0054] Example 2 The core-shell structure sintering flux provided in this embodiment is similar to that in Embodiment 1, except that the mass of the outer shell accounts for 40% of the total mass of the core-shell structure sintering flux.

[0055] The preparation method of the core-shell structure sintering flux provided in this embodiment is the same as that in embodiment 1, except that in step S1, the mass of the raw material of the sintering flux base powder is 590g; and in step S2, the mass of the shell dry mix is ​​400g.

[0056] Example 3 The core-shell structure sintering flux provided in this embodiment is similar to that in Embodiment 1, except that the alloy composition is an iron-titanium alloy (titanium content 70wt%) and a boron-iron alloy (boron content 10wt%). The total mass of the alloy composition accounts for 1.3% of the total mass of the core-shell structure sintering flux, the iron-titanium alloy accounts for 1% of the total mass of the core-shell structure sintering flux, and the boron-iron alloy accounts for 0.3% of the total mass of the core-shell structure sintering flux.

[0057] The preparation method of the core-shell structure sintering flux provided in this embodiment is the same as that in embodiment 1, except that in step S1, the mass of the raw materials of the alloy powder (iron-titanium alloy powder and boron-iron alloy powder, both with a particle size of 80~100 mesh) is 13g, and the mass of the raw materials of the sintering flux base powder is 787g.

[0058] Example 4 The core-shell structure sintering flux provided in this embodiment is similar to that in Embodiment 1, except that the mass of the outer shell accounts for 60% of the total mass of the core-shell structure sintering flux.

[0059] The preparation method of the core-shell structure sintering flux provided in this embodiment is the same as that in embodiment 1, except that in step S1, the mass of the raw material of the sintering flux base powder is 390g; and in step S2, the mass of the shell dry mix is ​​600g.

[0060] Example 5 The core-shell structure sintering flux provided in this embodiment is similar to that in Embodiment 1, except that the mass of the outer shell accounts for 10% of the total mass of the core-shell structure sintering flux.

[0061] The preparation method of the core-shell structure sintering flux provided in this embodiment is the same as that in embodiment 1, except that in step S1, the mass of the raw material of the sintering flux base powder is 890g; and in step S2, the mass of the shell dry mix is ​​100g.

[0062] Comparative Example 1 The sintered flux provided in this comparative example comprises, by weight percentage: 1% alloy component and 99% sintered flux base component; The alloy composition is an iron-titanium alloy with a titanium content of 70 wt%. The basic components of the sintered flux, by mass percentage, include: 40% CaF2, 35% MgO, and 25% Al2O3.

[0063] The method for preparing the sintering flux provided in this comparative example includes the following steps: 10g of alloy powder raw material (iron-titanium alloy powder, particle size 80-100 mesh) and 990g of sintered flux base powder raw material (CaF2 powder, MgO powder and Al2O3 powder, all particle size 300-400 mesh) were placed in a V-type mixer and mixed at a frequency of 0.5Hz for 90 minutes to obtain a dry mixture; the dry mixture with a mass ratio of 1:0.2 and water glass binder (sodium silicate modulus of 2.2-2.4) were stirred evenly to obtain a wet mixture; The wet mixture is placed in a disc granulator for granulation to form granules; the granules are then screened using a sieve to select flux green granules with a particle size of 1-2 mm. The flux blank particles were placed in a muffle furnace and heated to 800°C at a rate of 5°C / min and held for 2 hours. Then, the furnace was cooled to room temperature to obtain sintered flux.

[0064] Comparative Example 2: The sintered flux provided in this comparative example comprises, by weight percentage: 1.3% alloy component and 98.7% sintered flux base component; The alloy composition is an iron-titanium alloy (titanium content is 70 wt%) and a boron-iron alloy (boron content is 10 wt%), with a mass ratio of iron-titanium alloy to boron-iron alloy of 1:0.3; The basic components of the sintered flux, by mass percentage, include: 40% CaF2, 35% MgO, and 25% Al2O3.

[0065] The preparation method of the sintered flux provided in this comparative example is the same as that in Comparative Example 1, except that the mass of the raw materials of the alloy powder (iron-titanium alloy powder and boron-iron alloy powder, both with a particle size of 80-100 mesh) is 13g, and the mass of the raw materials of the sintered flux base powder is 987g.

[0066] Test case High heat input submerged arc welding was performed using the core-shell structure sintering fluxes prepared in Examples 1-5 and the sintering fluxes prepared in Comparative Examples 1-2. The transition amounts of the target element (titanium or boron) are shown in Table 1.

[0067] High heat input submerged arc welding: Flat plate welding was performed on EH36 ship plate steel using a high heat input of 60 kJ / cm. The welding process parameters were as follows: DC power supply was used for the front wire, with a welding current of 850 A and an arc voltage of 32 V; AC power supply was used for the rear wire, with a welding current of 625 A and an arc voltage of 36 V; the welding speed was controlled at 500 mm / min.

[0068] Titanium or Boron Transition Content: For weld metal formed by flux welding, inductively coupled plasma atomic emission spectrometry (ICP-AES) is used for quantitative chemical composition analysis to accurately determine the content of the target alloying element (titanium or boron). Subsequently, the contribution of the sintered flux to the weld metal composition is quantified using the Δ value. The Δ value represents the weld metal composition (C...). WM ) and nominal components (C N The difference is shown in Formula 1. The nominal component is the parent material component (C). BM ) and welding wire composition (C E The weighted sum of the contributions of each component under their respective contribution ratios is shown in Formula 2. Therefore, the Δ value is the net contribution of the flux to the weld metal composition after excluding the contributions of the welding wire and the base metal. Wherein, the contribution ratio of the base metal and the welding wire to the nominal composition (X) is the net contribution of the flux to the weld metal composition. BM With X E ) can be respectively determined by the area of ​​the weld penetration depth (A) BM ) and the area of ​​the remaining height (A) E ) accounts for the total weld area (A) WM The total weld area is calculated by the ratio of the weld penetration area to the weld reinforcement area, as shown in formulas 3 and 4. Figure 2 As shown, the area of ​​each part of the weld was obtained by measuring using ImageJ software.

[0069] Formula 1: ;Formula 2: ;Formula 3: ;Formula 4: .

[0070] Table 1

[0071] As can be seen from Table 1, the comparison between the examples and the comparative examples demonstrates that core-shell structure sintering flux can significantly improve the transition efficiency of alloying elements into the weld metal.

[0072] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A core-shell structure sintering flux, characterized in that, Includes the core and the outer shell covering the surface of the core; The core comprises alloy components and sintered flux base components; The outer shell comprises a sintered flux base component.

2. The core-shell structure sintering flux according to claim 1, characterized in that, The alloy composition includes iron-titanium alloys and / or boron-iron alloys.

3. The core-shell structure sintering flux according to claim 2, characterized in that, The titanium content in the iron-titanium alloy is 30wt%~70wt%; And / or, the boron content in the ferroborone alloy is 5wt%~25wt%.

4. The core-shell structure sintering flux according to claim 1, characterized in that, The basic components of the sintering flux, by mass parts, include: 35-45 parts CaF2, 25-35 parts MgO, and 20-30 parts Al2O3.

5. The core-shell structure sintering flux according to claim 1, characterized in that, The mass of the alloy component accounts for 0.5% to 3% of the total mass of the core-shell structure sintering flux; And / or, the mass of the outer shell accounts for 10% to 40% of the total mass of the core-shell structure sintering flux.

6. The method for preparing the core-shell structure sintering flux according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Mix the alloy powder and the sintering flux base powder to obtain a core dry mix; mix the core dry mix and the binder to obtain a core wet mix; after the core wet mix is ​​granulated and sieved, a core semi-finished product is obtained. S2. In the granulator, the core semi-finished product is sprayed with atomized binder while rolling, and sintered flux base powder is added to obtain flux green pellets. S3. After sintering the flux green particles, the core-shell structure sintered flux is obtained.

7. The method for preparing the core-shell structure sintering flux according to claim 6, characterized in that, In step S1, the particle size of the alloy powder is 80-100 mesh; And / or, in steps S1 and S2, the particle size of the sintered flux base powder is 300~400 mesh.

8. The method for preparing the core-shell structure sintering flux according to claim 6, characterized in that, Step S1 includes at least one of the following features (1) to (3); (1) The adhesive includes water glass adhesive; (2) The mass of the binder accounts for 15% to 25% of the total mass of the core dry mix; (3) The particle size of the core semi-finished product is 1~1.4mm.

9. The method for preparing the core-shell structure sintering flux according to claim 7, characterized in that, Includes at least one of the following features (1) to (3); (1) In step S2, the adhesive includes a water glass solution; (2) In step S2, the particle size of the flux green blank particles is 1~2mm; (3) In step S3, the sintering includes: heating to 650~850℃ and holding for 1.5~3.5h, followed by furnace cooling.

10. The application of the core-shell structure sintering flux as described in any one of claims 1 to 5 in high heat input submerged arc welding.

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