Sintered flux with high strength and low-temperature toughness, preparation method of sintered flux and application of sintered flux in wind power tower drum

Abstract

The invention discloses a sintered flux with high strength and low-temperature toughness, a preparation method of the sintered flux and application of the sintered flux in a wind power tower drum. The invention belongs to the technical field of welding materials. The invention aims to solve the technical problem that a welding seam cannot have high strength and high low-temperature toughness at the same time by the existing welding flux for submerged-arc welding. The flux is prepared from mineral dry powder and a binder. The mineral dry powder comprises, by mass, 20%-40% of fused magnesite, 25%-40% of bauxite, 15%-25% of fluorite, 10%-20% of mica, 1%-6% of manganese ore, 1%-3% of rare earth oxide and 2%-10% of silicon-manganese alloy. When the welding flux is used in cooperation with a low-alloy high-strength steel welding wire, it can be guaranteed that components of a welding seam are uniform, and meanwhile excellent strength and low-temperature toughness are achieved. The obtained welding bead is smooth in surface, good in deslagging performance and free of defects, meets the welding performance and process requirements of the wind power tower drum, and can be used for welding the low-alloy high-strength steel plate for the wind power tower drum.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding materials, and particularly relates to a sintered welding flux with both high strength and low-temperature toughness, a preparation method thereof, and an application in a wind power tower barrel. Background Art

[0002] The wind turbine tower barrel is a key supporting structure of a wind power generation unit. At the current stage of the rapid development of the wind power industry, a large number of tower barrels need to be produced to support the operation of the wind turbines. In the cold "Three-North" regions, the installed wind energy capacity accounts for 76% of the country, and the lowest winter temperature is below -30°C. Therefore, relatively high requirements are imposed on the low-temperature impact toughness of the tower barrel. During the assembly process of the tower frame, automatic submerged arc welding is widely used because of its advantages such as large welding current, high production efficiency, and stable welding quality. The welding flux is one of the important consumable materials for submerged arc welding, and it plays roles of mechanical protection, metallurgical treatment, and improving welding process performance during the welding process. The welding process performance and chemical metallurgical performance of the welding flux are the key factors determining the quality of the weld metal. To meet the urgent need for the long-term stable use of wind power tower barrels in low-temperature environments, it is necessary to develop a sintered welding flux with excellent high strength and high and low-temperature toughness to solve the restrictive problems of the tower barrels in the application regions. Summary of the Invention

[0003] The purpose of the present invention is to solve the technical problem that the welding flux for submerged arc welding at present cannot make the weld have both high strength and high and low-temperature toughness, and thus provides a sintered welding flux with both high strength and low-temperature toughness, a preparation method thereof, and an application in a wind power tower barrel.

[0004] One of the purposes of the present invention is to provide a sintered welding flux with both high strength and low-temperature toughness. The welding flux is prepared from mineral dry powder and a binder. The components of the mineral dry powder and their mass percentages are as follows: fused magnesia 20% - 40%, bauxite 25% - 40%, fluorite 15% - 25%, mica 10% - 20%, manganese ore 1% - 6%, rare earth oxide 1% - 3%, ferrosilicon manganese 2% - 10%.

[0005] Further defined, the rare earth oxide is yttrium oxide, lanthanum oxide or cerium oxide.

[0006] Further defined, the mass of the binder accounts for 18% - 30% of the total mass of the mineral dry powder.

[0007] Further defined, the binder is potassium-sodium water glass, the potassium-sodium ratio is 1:1 - 3:1, the modulus is 2.91 - 2.93, and the Baumé degree is 41 - 45.5.

[0008] Another purpose of the present invention is to provide a preparation method of the above-mentioned welding flux. The method:

[0009] Weigh each component proportionally, and prepare the welding flux through mixing, granulation, sintering and sieving.

[0010] Further limit that the granulation is carried out until the particle size is 12 - 40 mesh. Crush the particles with a particle size less than 12 mesh, and re-granulate the particles with a particle size greater than 40 mesh.

[0011] Further limit that the sintering temperature is 600 - 850 °C and the time is 0.5 - 2 h.

[0012] The third object of the present invention is to provide a welding method used in conjunction with the above-mentioned welding flux. The method:

[0013] Adopt single-sided single-wire V-groove submerged arc welding for filling, with direct current reverse connection.

[0014] Further limit that the welding current is 500 - 600 A, the arc voltage is 25 - 35 V, and the welding speed is 400 - 500 mm / min.

[0015] The fourth object of the present invention is to provide an application of the above-mentioned welding method. Using a low-alloy high-strength steel wire as the welding material, it is used for welding low-alloy high-strength steel plates for wind power tower barrels.

[0016] Further limit that the low-alloy high-strength steel is Q345E steel, and the low-alloy high-strength steel wire is H10Mn2SiNiMoG.

[0017] The fifth object of the present invention is to provide a welded joint obtained by the above application, with a tensile strength > 690 MPa, a yield strength > 620 MPa, a -40 °C Charpy impact absorption energy > 80 J, and an elongation > 20%.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The present invention meets the urgent demand for a welding flux for submerged arc welding under the requirements of high strength and high toughness of wind power tower barrels, and develops a high-strength sintered welding flux with stable welding process, high strength of weld metal, uniform weld tissue composition and excellent weld formability. The innovation lies in optimizing the control of the weld tissue by introducing trace rare earth oxides and optimizing the content of rare earth oxides. During the welding thermal cycle, the rare earth oxides decompose thermally and transition into the molten pool, and undergo selective metallurgical reactions with impurity elements in the weld metal, showing significant effects of dehydrogenation, desulfurization and grain boundary purification. Specifically, the addition of rare earth elements can effectively control the morphological characteristics of inclusions in the weld, changing them from irregular blocks to fine and dispersed spherical shapes, and significantly reducing the inclusion size. This improvement in the microstructure provides favorable conditions for the nucleation of acicular ferrite and granular bainite, while the formation of proeutectoid ferrite is significantly inhibited, and the content control is particularly important among them. Through the above tissue optimization mechanism, both the strength and low-temperature impact toughness of the weld metal are significantly improved, achieving the coordinated improvement of weld strength and toughness. When the welding flux of the present invention is used in combination with a low-alloy high-strength steel wire, it can ensure uniform weld composition, and at the same time has excellent strength and low-temperature toughness. The obtained weld bead surface is smooth, the slag removal performance is good, and it is detected and confirmed to be defect-free, fully meeting the performance and process requirements of wind power tower barrel welding. Brief Description of the Drawings

[0020] Figure 1 Optical micrograph of the cut section of the welded joint formed in Example 1;

[0021] Figure 2 Metallographic micrograph of the weld formed in Example 1;

[0022] Figure 3 Morphology diagram of the weld form and the slag shell after welding in Example 1. Detailed Description of the Invention

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0024] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used are all conventional materials, reagents, methods and instruments in this field, and those skilled in the art can obtain them through commercial channels without special instructions.

[0025] Example 1:

[0026] The sintered welding flux with both high strength and low temperature toughness for wind power tower barrels in this embodiment is prepared from mineral dry powder and binder. Among them, the mineral dry powder is by mass percentage: fused magnesite 29%, bauxite 30%, fluorite 20%, mica 15%, manganese ore 2%, lanthanum oxide 1%, ferrosilicon manganese alloy (silicon to manganese mass ratio is 3:7) 3%.

[0027] The preparation method of the sintered welding flux with both high strength and low temperature toughness for wind power tower barrels in this embodiment includes the following steps:

[0028] Step 1, mixing:

[0029] Weigh each raw material accurately according to the proportion of the mineral dry powder of the sintered welding flux and place them in a mixing container basin, stir until the powder materials are evenly mixed to obtain dry-mixed raw materials;

[0030] Add 18% of the mass of the dry-mixed raw materials of the potassium-sodium ratio 1:1 mixed water glass (modulus is 2.93, Baume degree is 45) for wet mixing and stirring to prepare a semi-solid wet-mixed material;

[0031] Step 2, granulation:

[0032] Pour the semi-solid wet-mixed material into a granulator for granulation for 5 minutes, and perform sieving treatment through 12 - 40 meshes to obtain particles of 12 - 40 meshes as semi-finished products;

[0033] Crush the particles with a particle size less than 12 meshes, and perform re-granulation treatment on the particles with a particle size greater than 40 meshes until all particles become semi-finished products of 12 - 40 meshes;

[0034] To evaporate the attached water on the surface of the wet material particles, dry the semi-finished products at 200°C for 1.5 hours;

[0035] Step 3, sintering:

[0036] Place the semi-finished products in a box-type resistance furnace for sintering, the sintering temperature is 600°C, and the sintering time is 2 hours.

[0037] Step 4, sieving:

[0038] Pass the sintered particles through a 12 - 40 mesh sieve to obtain the sintered welding flux.

[0039] Dry the above-mentioned welding flux in this embodiment in a drying oven at 300°C for 2 hours and then use it in combination with H10Mn2SiNiMoG low-alloy high-strength steel wire for welding low-alloy high-strength steel (Q345E steel) for wind power tower barrels. The welding method is: adopt single-sided single-wire V-groove submerged arc welding for filling, direct current reverse connection, the welding current is 550A, the arc voltage is 30V, and the welding speed is 450mm / min.

[0040] The properties of the welded joint are as follows: the tensile strength is 702 MPa, the yield strength is 625 MPa, the Charpy impact energy absorbed at -40 °C is 104 J, and the elongation is 25%.

[0041] The optical micrograph of the cut section of the welded joint is as shown in Figure 1 shown, and the metallographic micrograph of the weld seam is as shown in Figure 2 shown, and the morphology diagrams of the weld formation and the detached slag shell are as shown in Figure 3 shown. It can be seen that the welding processability is good, the weld formation is beautiful, the weld composition is uniform, and the slag removal performance is good.

[0042] Example 2

[0043] The sintered welding flux with both high strength and low-temperature toughness for the wind power tower tube in this example is prepared from mineral dry powder and binder. Among them, the mineral dry powder is in the following mass percentages: fused magnesite 30%, bauxite 26%, fluorite 21%, mica 15%, manganese ore 4%, cerium oxide 1%, and ferrosilicon manganese alloy (silicon to manganese mass ratio is 3:7) 3%.

[0044] The preparation method of the sintered welding flux with both high strength and low-temperature toughness for the wind power tower tube in this example includes the following steps:

[0045] Step 1, mixing:

[0046] Weigh each raw material accurately according to the proportion of the mineral dry powder of the sintered welding flux and place them in a mixing container basin, stir until the powder materials are evenly mixed to obtain the dry-mixed raw materials;

[0047] Add the potassium-sodium ratio of 3:1 mixed water glass (modulus is 2.91, Baume degree is 43.5) at 22% of the mass of the dry-mixed raw materials for wet mixing and stirring to prepare a semi-solid wet-mixed material;

[0048] Step 2, granulation:

[0049] Pour the semi-solid wet-mixed material into a granulator for granulation for 5 minutes, and perform sieving treatment through 12 - 40 meshes to obtain particles of 12 - 40 meshes as semi-finished products;

[0050] Crush the particles with a particle size less than 12 meshes, and perform re-granulation treatment on the particles with a particle size greater than 40 meshes until all the particles become semi-finished products of 12 - 40 meshes;

[0051] To evaporate the attached water on the surface of the wet material particles, dry the semi-finished products at 250 °C for 1 hour;

[0052] Step 3, sintering:

[0053] Place the semi-finished products in a box-type resistance furnace for sintering, the sintering temperature is 700 °C, and the sintering time is 1.5 hours.

[0054] Step 4, sieving:

[0055] The sintered particles are passed through a 12 - 40 mesh sieve to obtain the sintered welding flux.

[0056] The above welding flux of this embodiment is dried in a drying oven at 400 °C for 1.5 h and then used in combination with H10Mn2SiNiMoG low - alloy high - strength steel wire for welding low - alloy high - strength steel (Q345E steel) used in wind power tower barrels. The welding method is: single - sided single - wire V - groove submerged arc welding for filling, direct current reverse connection, welding current is 550 A, arc voltage is 30 V, and welding speed is 450 mm / min.

[0057] The properties of the welded joint are as follows: tensile strength is 708 MPa, yield strength is 627 MPa, Charpy impact energy at - 40 °C is 107 J, elongation is 25%, the welding processability is good, the weld formation is beautiful, the weld composition is uniform, and the slag - removing performance is good.

[0058] Example 3

[0059] The sintered welding flux with both high strength and low - temperature toughness for wind power tower barrels in this embodiment is prepared from mineral dry powder and binder. Among them, the mineral dry powder by mass percentage is: fused magnesite 28%, bauxite 26%, fluorite 23%, mica 14%, manganese ore 5%, cerium oxide 2%, ferrosilicon manganese (silicon - manganese mass ratio is 3:7) 2%.

[0060] The preparation method of the sintered welding flux with both high strength and low - temperature toughness for wind power tower barrels in this embodiment includes the following steps:

[0061] Step 1, mixing:

[0062] According to the proportion of the mineral dry powder of the sintered welding flux, each raw material is accurately weighed and placed in a mixing container basin, and stirred until the powder materials are evenly mixed to obtain the dry - mixed raw materials;

[0063] Potassium - sodium ratio of 1:1 mixed water glass (modulus is 2.93, Baume degree is 42) is added at 25% of the mass of the dry - mixed raw materials for wet - mixing and stirring to prepare a semi - solid wet - mixed material;

[0064] Step 2, granulation:

[0065] The semi - solid wet - mixed material is poured into a granulator for granulation for 5 min, and is sieved through a 12 - 40 mesh to obtain 12 - 40 mesh particles as semi - finished products;

[0066] The particles with a particle size less than 12 mesh are crushed, and the particles with a particle size greater than 40 mesh are re - granulated until all the particles become 12 - 40 mesh semi - finished products;

[0067] To evaporate the attached water on the surface of the wet material particles, the semi-finished product is dried at 300 °C for 1 h;

[0068] Step 3, sintering:

[0069] The semi-finished product is placed in a box-type resistance furnace for sintering. The sintering temperature is 750 °C and the sintering time is 1 h.

[0070] Step 4, sieving:

[0071] The sintered particles are passed through a 12-40 mesh sieve to obtain the sintered welding flux.

[0072] The welding flux of this embodiment is dried in a drying oven at 350 °C for 2 h and then used in combination with an H10Mn2SiNiMoG low-alloy high-strength steel wire for welding low-alloy high-strength steel (Q345E steel) for wind power tower barrels. The welding method is: single-sided single-wire V-groove submerged arc welding for filling, direct current reverse connection, welding current is 550 A, arc voltage is 30 V, and welding speed is 450 mm / min.

[0073] The performance of the welded joint is as follows: tensile strength is 716 MPa, yield strength is 630 MPa, -40 °C Charpy impact absorption energy is 111 J, elongation is 26%, the welding processability is good, the weld formation is beautiful, the weld composition is uniform, and the slag removal performance is good.

[0074] Example 4

[0075] The sintered welding flux for wind power tower barrels with both high strength and low-temperature toughness in this embodiment is prepared from mineral dry powder and binder. Among them, the mineral dry powder is by mass percentage: fused magnesia 30%, bauxite 29%, fluorite 20%, mica 10%, manganese ore 5%, yttrium oxide 3%, ferrosilicon manganese (silicon-manganese mass ratio is 3:7) 3%.

[0076] The preparation method of the sintered welding flux for wind power tower barrels with both high strength and low-temperature toughness in this embodiment includes the following steps:

[0077] Step 1, mixing:

[0078] According to the mineral dry powder ratio of the sintered welding flux, accurately weigh each raw material and place it in a mixing container basin, and stir until the powder materials are evenly mixed to obtain the dry-mixed raw materials;

[0079] Potassium-sodium ratio of 3:1 mixed water glass (modulus 2.91, Baume degree 43) is added at 20% of the mass of the dry-mixed raw materials for wet mixing and stirring to prepare a semi-solid wet-mixed material;

[0080] Step 2, granulation:

[0081] Pour the semi-solid wet mixture into a granulator for granulation for 5 minutes, and perform sieving treatment through a 12-40 mesh sieve to obtain particles of 12-40 mesh as semi-finished products;

[0082] Crush the particles with a particle size less than 12 mesh, and perform re-granulation on the particles with a particle size greater than 40 mesh until all particles become semi-finished products of 12-40 mesh;

[0083] To evaporate the attached water on the surface of the wet material particles, dry the semi-finished products at 300 °C for 0.5 h;

[0084] Step 3, sintering:

[0085] Place the semi-finished products in a box-type resistance furnace for sintering at a sintering temperature of 800 °C for 0.5 h.

[0086] Step 4, sieving:

[0087] Pass the sintered particles through a 12-40 mesh sieve to obtain a sintered welding flux.

[0088] Dry the welding flux of this embodiment in a drying oven at 450 °C for 1 h and then use it in combination with an H10Mn2SiNiMoG low-alloy high-strength steel wire for welding low-alloy high-strength steel (Q345E steel) used for wind power tower barrels. The welding method is: adopt single-sided single-wire V-groove submerged arc welding for filling, direct current reverse connection, welding current is 550 A, arc voltage is 30 V, and welding speed is 450 mm / min.

[0089] The performance of the welded joint is as follows: the tensile strength is 720 MPa, the yield strength is 633 MPa, the -40 °C Charpy impact absorption energy is 116 J, the elongation is 26%, the welding processability is good, the weld formation is beautiful, the weld composition is uniform, and the slag removal performance is good.

[0090] The above is only the preferred specific implementation manners of the present invention. These specific implementation manners are all different implementation manners based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A sintered flux having both high strength and low temperature toughness, characterized in that: The flux is prepared from mineral dry powder and a binder. The mineral dry powder components and their mass percentages are: 20% to 40% fused magnesia, 25% to 40% bauxite, 15% to 25% fluorite, 10% to 20% mica, 1% to 6% manganese ore, 1% to 3% rare earth oxide, and 2% to 10% silicon-manganese alloy.

2. The flux according to claim 1, characterized in that The rare earth oxide is yttrium oxide, lanthanum oxide or cerium oxide.

3. The flux according to claim 1, characterized in that The mass of the binder accounts for 18% to 30% of the total mass of the mineral dry powder.

4. The method for preparing the flux according to any one of claims 1 to 3, characterized in that: The method: The components are weighed in proportion, and the flux is obtained through mixing, granulation, sintering and sieving.

5. The method according to claim 4, characterized in that Granulate to a particle size of 12 to 40 mesh.

6. The method according to claim 4, characterized in that The sintering temperature is 600-850°C and the time is 0.5-2h.

7. A welding method used in conjunction with the flux according to any one of claims 1 to 3, characterized in that: The method: Use single-sided single-wire V-groove submerged arc welding for filling and DC reverse connection.

8. The method according to claim 7, characterized in that The welding current is 500-600A, the arc voltage is 25-35V, and the welding speed is 400-500mm / min.

9. Application of the welding method according to claim 7, characterized in that: Low alloy high strength steel welding wire is used as welding material for welding low alloy high strength steel plates for wind turbine towers.

10. The welded joint obtained by the application of claim 9, characterized in that: Tensile strength>690MPa, yield strength>620MPa, -40℃ Charpy impact absorption energy>80J, elongation>20%.

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