650mpa grade ultra supercritical high temperature steel welding electrode and coating, deposited metal

Abstract

The application provides a 650MPa-grade ultra-supercritical high-temperature steel welding electrode and a coating and deposited metal, and belongs to the field of welding materials.The raw material of the coating comprises, in weight parts, 39-43 parts of magnesia, 30-35 parts of fluorite, 3-5 parts of dolomite, 5-10 parts of ferrosilicon, 2-5 parts of sodium titanate, 10-15 parts of metallic chromium powder, 0.1-0.4 parts of chromium oxide green, 0.1-0.3 parts of aluminum-magnesium alloy and 1.5-2.5 parts of sodium alginate.Through the research on the composition of the coating, the sodium titanate and the aluminum-magnesium alloy are added to stabilize the electric arc, the electric arc has stability and concentration when high-current welding is performed, the weld pool temperature is moderate, the fluidity of the molten iron is moderate, the electric arc blowing force is stable and concentrated, and the welding operation performance is good.

Description

Technical Field

[0001] This application relates to the field of welding materials technology, and in particular to a welding electrode, coating, and deposited metal for welding 650MPa grade ultra-supercritical high-temperature steel. Background Technology

[0002] 650MPa grade ultra-supercritical high temperature steel welding electrodes are mainly used for the repair welding of ZG12Cr9Mo1Co1NiVNbNB cast steel parts and the welding of structural parts in the high temperature cylinders of steam turbines in thermal power generation equipment.

[0003] Cast steel parts are prone to porosity defects during the casting process. To ensure safety in subsequent use, the defective areas need to be ground down and repaired using matching welding materials. Factory construction involves a large amount of welding work with tight deadlines, complex workpiece structures, and wall thicknesses exceeding 100mm, resulting in extremely high weld stress. Welding materials used for repairing cast steel parts need to improve welding efficiency and be able to withstand high-current welding; on the other hand, the crack resistance of the cladding metal must also be considered. Therefore, how to improve arc stability and concentration during high-current welding while ensuring the crack resistance of the cladding metal is a pressing technical problem that needs to be solved. Summary of the Invention

[0004] This application provides a welding electrode, coating, and deposited metal for welding 650MPa grade ultra-supercritical high-temperature steel, in order to solve the technical problem that existing welding electrodes used for repair welding of cast steel parts are difficult to improve the arc stability and concentration during high-current welding while ensuring the crack resistance of the deposited metal.

[0005] In a first aspect, this application provides a flux coating for welding 650MPa grade ultra-supercritical high-temperature steel, wherein the raw materials of the flux coating, by weight, comprise:

[0006] Magnesia: 39-43 parts, Fluorite: 30-35 parts, Dolomite: 3-5 parts, Ferrosilicon: 5-10 parts, Sodium titanate: 2-5 parts, Metallic chromium powder: 10-15 parts, Chromium oxide green: 0.1-0.4 parts, Aluminum-magnesium alloy: 0.1-0.3 parts, Sodium alginate: 1.5-2.5 parts.

[0007] Optionally, the raw materials for the medicated coating are, by weight, the following:

[0008] Magnesia: 40 parts, Fluorite: 32 parts, Dolomite: 3.5 parts, Ferrosilicon: 7 parts, Sodium Titanate: 3 parts, Chromium Powder: 10 parts, Chromium Oxide Green: 0.3 parts, Aluminum-Magnesium Alloy: 0.2 parts, Sodium Alginate: 2 parts; or,

[0009] Magnesia: 41 parts, Fluorite: 33 parts, Dolomite: 4 parts, Ferrosilicon: 6 parts, Sodium titanate: 4 parts, Chromium metal powder: 11 parts, Chromium oxide green: 0.3 parts, Aluminum-magnesium alloy: 0.2 parts, Sodium alginate: 2 parts.

[0010] Optionally, in the magnesia, the mass percentage of MgCO3 is ≥95%, the mass percentage of S is ≤0.01%, and the mass percentage of P is ≤0.02%; and / or,

[0011] In the fluorite, the mass percentage of CaF2 is ≥98%, the mass percentage of SiO2 is ≤1.0%, the mass percentage of C is ≤0.05%, the mass percentage of S is ≤0.01%, and the mass percentage of P is ≤0.02%; and / or,

[0012] In the dolomite, the mass percentage of CaCO3 is ≥50%, the mass percentage of MgCO3 is ≥40%, the mass percentage of S is ≤0.03%, and the mass percentage of P is ≤0.03%; and / or,

[0013] In the ferrosilicon, the mass percentage of Si is 42%–47%, the mass percentage of S is ≤0.02%, the mass percentage of P is ≤0.03%, and the mass percentage of C is ≤0.05%; and / or,

[0014] In the sodium titanate, the mass percentage of TiO2 is ≥72%, the mass percentage of Na2O is ≥16%, the mass percentage of S is ≤0.02%, and the mass percentage of P is ≤0.03%; and / or,

[0015] In the chromium powder, the mass percentage of Cr is ≥99.9%; and / or,

[0016] In the aluminum-magnesium alloy, the sum of the mass percentages of Al and Mg is ≥97.5%, and the mass percentage of Al is 47% to 53%.

[0017] Optionally, the particle size requirements for the magnesite are: 100% by mass of -40 mesh and ≤60% by mass of -150 mesh; and / or,

[0018] The particle size requirements for the fluorite are: 100% by mass of -40 mesh and ≤60% by mass of -150 mesh; and / or,

[0019] The dolomite particle size requirements are: -40 mesh ≤ 100% by mass, -150 mesh ≤ 60% by mass; and / or,

[0020] The particle size requirement for the ferrosilicon is: -40 mesh accounts for 100% by mass; and / or,

[0021] The particle size requirement for the sodium titanate is: -80 mesh ≥ 95% by mass; and / or,

[0022] The particle size requirement for the chromium powder is: -60 mesh accounts for 100% by mass; and / or,

[0023] The required particle size of the aluminum-magnesium alloy particles is: -80 mesh ≥ 95% by mass.

[0024] Secondly, this application provides a welding electrode for welding 650MPa grade ultra-supercritical high-temperature steel. The welding electrode includes a core and a coating, wherein the coating covers the core, and the coating is the coating described in any embodiment of the first aspect. Wherein, if the diameter of the welding electrode is 4.0mm, the maximum operating current of the welding electrode is 200A; if the diameter of the welding electrode is 5.0mm, the maximum operating current of the welding electrode is 240A.

[0025] Optionally, the chemical composition of the welding core, in mass fraction, includes:

[0026] C: 0.13%–0.16%, Mn: 0.70%–1.40%, Si: 0.10%–0.30%, Cr: 7.0%–8.0%, Mo: 1.50%–1.70%, V: 0.30%–0.40%, Nb: 0.05%–0.07%, N: 0.005%–0.01%, B: 0.007%–0.015%, Co: 0.90%–1.50%, and Fe.

[0027] Thirdly, this application provides a method for preparing the welding electrode described in the second aspect embodiment, the method comprising:

[0028] The raw materials of the medicinal peel are mixed to obtain the first mixture;

[0029] The first mixture is mixed with the adhesive to obtain the second mixture;

[0030] The second mixture is coated onto the outside of the welding core to obtain a semi-finished welding electrode;

[0031] The semi-finished product is subjected to quasi-low temperature baking, low temperature baking, and high temperature baking to obtain welding rods.

[0032] Fourthly, this application provides a cladding metal for welding 650MPa grade ultra-supercritical high-temperature steel, wherein the cladding metal is obtained by welding the electrode described in the embodiment of the second aspect during the welding process.

[0033] Optionally, the chemical composition of the deposited metal, in mass fraction, includes:

[0034] C: 0.12%–0.16%, Mn: 0.60%–1.40%, Si: 0.01%–0.50%, Cr: 9.0%–11.0%, Mo: 1.40%–1.70%, V: 0.30%–0.40%, Nb: 0.04%–0.07%, N: 0.005%–0.02%, B: 0.005%–0.015%, Co: 0.80%–1.50%, Al: 0.0001%–0.005%, Ca: 0.0001%–0.005%, and Fe.

[0035] Optionally, the deposited metal satisfies at least one of the following properties: room temperature tensile strength of 650MPa to 800MPa, room temperature yield strength of 530MPa to 700MPa, room temperature elongation after fracture of 15% to 30%, impact strength at 20℃ of 41J to 120J, and HB hardness of 180 to 350.

[0036] The technical solutions provided in this application have the following advantages compared with the prior art:

[0037] This application provides a flux coating suitable for welding 650MPa grade ultra-supercritical high-temperature steel. Through research on the composition of the flux coating, sodium titanate and aluminum-magnesium alloy are added to stabilize the arc. During high-current welding, the arc has stability and concentration. At the same time, the weld pool temperature is moderate, the molten iron fluidity is moderate, the arc blowing force is stable and concentrated, and the welding operation performance is good. Attached Figure Description

[0038] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0039] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a schematic flowchart illustrating a method for preparing welding electrodes suitable for welding 650MPa-grade ultra-supercritical high-temperature steel, as provided in an embodiment of this application. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0042] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0043] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, a~b (i.e., a and b), a~c, b~c, or a~b~c, where a, b, and c can be a single or multiple.

[0044] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0045] This application provides a flux coating suitable for welding 650MPa grade ultra-supercritical high-temperature steel, wherein the raw materials of the flux coating, by weight, comprise:

[0046] Magnesia: 39-43 parts, Fluorite: 30-35 parts, Dolomite: 3-5 parts, Ferrosilicon: 5-10 parts, Sodium titanate: 2-5 parts, Metallic chromium powder: 10-15 parts, Chromium oxide green: 0.1-0.4 parts, Aluminum-magnesium alloy: 0.1-0.3 parts, Sodium alginate: 1.5-2.5 parts.

[0047] Magnesia, fluorite, and dolomite serve to provide slag and gas. Magnesia's main component, MgCO3, decomposes to produce MgO and CO2. Dolomite's main components, MgCO3 and CaCO3, decompose to produce MgO, CaO, and CO2. The combined action of magnesia and dolomite generates a large amount of gas and slag. The gas enters the molten pool, stirring it. This stirring facilitates redox reactions in the molten pool and allows gas to escape; the slag then floats to the surface. The slag, composed of MgO, CaO, and SiO2, forms calcium silicate and magnesium silicate. The slag removes carbon, silicon, and phosphorus from the molten iron, reducing impurities and purifying the weld, thus improving its strength, impact toughness, and crack resistance. The role of fluorite is to improve the fluidity of the molten iron in the weld pool, provide slag, and remove hydrogen. Fluorite (mainly CaF2) decomposes to produce CaO and F. The F reacts with the water of crystallization in the coating and combines with H in the molten pool to form HF, reducing diffusible hydrogen in the weld and improving its crack resistance. However, the F in fluorite can also cause arc instability and produce the harmful gas HF, so the optimal weight range needs to be determined through multiple experiments. Simultaneously, the magnesite, fluorite, and dolomite in the coating increase the basicity of the coating, reducing the content of diffusible hydrogen in the weld metal and further improving crack resistance. For example, the weight parts of the magnesite can be 39, 40, 41, 42, or 43 parts; the weight parts of the fluorite can be 30, 31, 32, 33, 34, or 35 parts; and the weight parts of the dolomite can be 3, 3.5, 4, 4.5, or 5 parts.

[0048] Aluminum-magnesium alloys stabilize the electric arc, especially improving arc stability and concentration during high-current welding. They also remove sulfur and other impurities, enhancing the crack resistance of the weld metal. For example, the aluminum-magnesium alloy can be present in weight proportions of 0.1 parts, 0.15 parts, 0.20 parts, 0.25 parts, 0.3 parts, etc.

[0049] The main alloying elements added to the core of the welding electrode in this application are 9% Cr and 1.5% Mo. The resistance of the core is higher than that of a carbon steel core without alloying elements. When welding with a current of 170A or higher for a 4.0 mm electrode and 190A or higher for a 5.0 mm electrode, the core of the electrode easily turns red. The heat generated by the red-hot core causes some of the flux powder in the coating to undergo a redox reaction before it melts into the molten pool. This reduces the effectiveness of the flux coating in entering the molten pool after melting and causes the flux coating to fall off the core, affecting the welder's operation and the mechanical properties of the weld. The red-hot core during welding is due to the fact that the physical properties of the core cannot be changed. The increased resistance of the core due to the addition of alloying elements such as Cr and Mo causes the core to heat up when current passes through it. The longer the current is applied, the more severe the heating becomes, resulting in the red-hot core. Therefore, this application adds chromium oxide green to the flux coating. This material participates in the redox reaction in the molten pool, generating a large amount of heat, which helps to increase the molten pool temperature, accelerate the melting rate of the electrode (core and flux coating), reduce the energizing time of the core, thereby improving the reddening of the core. This ensures good electrode process performance and good weld mechanical properties, and also speeds up welding, which helps to improve welding efficiency and welder comfort. For example, the weight parts of the chromium oxide green can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, etc.

[0050] The sodium element in sodium titanate powder plays a stabilizing role in the electric arc during welding. For example, the sodium titanate can be present in parts by weight of 2, 2.5, 3, 3.5, 4, 4.5, or 5 parts.

[0051] Soda ash is added as a binder, working together with sodium alginate and water glass to give the flux powder viscosity and slipperiness, ensuring smooth electrode production and preventing the flux coating from easily detaching from the core after drying. For example, the sodium alginate can be present in parts by weight of 1.5 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.4 parts, 2.5 parts, etc.

[0052] For example, the weight parts of the metallic chromium powder can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, etc.; the weight parts of the ferrosilicon can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc.

[0053] In some embodiments, the raw materials of the medicated coating include, by weight:

[0054] Magnesia: 40 parts, Fluorite: 32 parts, Dolomite: 3.5 parts, Ferrosilicon: 7 parts, Sodium Titanate: 3 parts, Chromium Powder: 10 parts, Chromium Oxide Green: 0.3 parts, Aluminum-Magnesium Alloy: 0.2 parts, Sodium Alginate: 2 parts; or,

[0055] Magnesia: 41 parts, Fluorite: 33 parts, Dolomite: 4 parts, Ferrosilicon: 6 parts, Sodium titanate: 4 parts, Chromium metal powder: 11 parts, Chromium oxide green: 0.3 parts, Aluminum-magnesium alloy: 0.2 parts, Sodium alginate: 2 parts.

[0056] In some embodiments, the magnesia contains ≥95% MgCO3, ≤0.01% S, and ≤0.02% P by mass; the fluorite contains ≥98% CaF2, ≤1.0% SiO2, ≤0.05% C, ≤0.01% S, and ≤0.02% P by mass; and the dolomite contains ≥50% CaCO3, ≥40% MgCO3, ≤0.03% S, and ≤0.02% P by mass. 0.03%; In the ferrosilicon, the mass percentage of Si is 42%–47%, the mass percentage of S is ≤0.02%, the mass percentage of P is ≤0.03%, and the mass percentage of C is ≤0.05%; In the sodium titanate, the mass percentage of TiO2 is ≥72%, the mass percentage of Na2O is ≥16%, the mass percentage of S is ≤0.02%, and the mass percentage of P is ≤0.03%; In the metallic chromium powder, the mass percentage of Cr is ≥99.9%; In the aluminum-magnesium alloy, the sum of the mass percentages of Al and Mg is ≥97.5%, and the mass percentage of Al is 47%–53%.

[0057] In some embodiments, the particle size requirements for the magnesite are: 100% by mass of -40 mesh and ≤60% by mass of -150 mesh; the particle size requirements for the fluorite are: 100% by mass of -40 mesh and ≤60% by mass of -150 mesh; the particle size requirements for the dolomite are: 100% by mass of -40 mesh and ≤60% by mass of -150 mesh; the particle size requirements for the ferrosilicon are: 100% by mass of -40 mesh; the particle size requirements for the sodium titanate are: ≥95% by mass of -80 mesh; the particle size requirements for the metallic chromium powder are: 100% by mass of -60 mesh; and the particle size requirements for the aluminum-magnesium alloy particles are: ≥95% by mass of -80 mesh.

[0058] This application provides a welding electrode suitable for welding 650MPa grade ultra-supercritical high-temperature steel. The welding electrode includes a core and a coating, with the coating covering the core. If the diameter of the welding electrode is 4.0mm, the maximum working current of the welding electrode is 200A; if the diameter of the welding electrode is 5.0mm, the maximum working current of the welding electrode is 240A.

[0059] Research on the composition of the electrode coating revealed that the addition of sodium titanate and aluminum-magnesium alloy stabilizes the arc, particularly improving arc stability and concentration during high-current welding. This patented electrode, with a diameter of 4.0mm, can operate at a maximum current of 200A, and with a diameter of 5.0mm, it can operate at a maximum current of 240A. At these currents, the weld pool temperature and molten metal fluidity are moderate, the arc force is stable and concentrated, and the welder's operational performance is excellent. Traditional welding electrodes typically recommend currents of 140A–170A for 4.0mm electrodes and 170A–200A for 5.0mm electrodes. Exceeding these currents results in uneven arc force, increased spatter and smoke, and irregular weld formation. The electrode provided in this application better meets market needs, improving production efficiency while ensuring quality.

[0060] In some embodiments, the chemical composition of the solder core, by mass fraction, includes:

[0061] C: 0.13%–0.16%, Mn: 0.70%–1.40%, Si: 0.10%–0.30%, Cr: 7.0%–8.0%, Mo: 1.50%–1.70%, V: 0.30%–0.40%, Nb: 0.05%–0.07%, N: 0.005%–0.01%, B: 0.007%–0.015%, Co: 0.90%–1.50%, and Fe.

[0062] This welding core contains alloying elements, resulting in a higher electrical resistance than unalloyed carbon steel welding cores. It is also more prone to red-heating under high current. For example, the C content can be 0.13%, 0.14%, 0.15%, 0.16%, etc.; the Mn content can be 0.70%, 0.80%, 0.90%, 1.0%, 1.10%, 1.20%, 1.30%, 1.40%, etc.; the Si content can be 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, etc.; the Cr content can be 7.0%, 7.2%, 7.4%, 7.6%, 7.8%, 8.0%, etc.; the Mo content can be 1.50%, 1.55%, 1.60%, 1.62%, 1.65%, 1.70%, etc.; and the V content can be... The content of Nb can be 0.30%, 0.32%, 0.34%, 0.36%, 0.38%, 0.40%, etc.; the content of Nb can be 0.05%, 0.06%, 0.07%, etc.; the content of N can be 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, etc.; the content of B can be 0.007%, 0.008%, 0.009%, 0.010%, 0.011%, 0.013%, 0.014%, 0.015%, etc.; the content of Co can be 0.90%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.50%, etc.

[0063] Figure 1 This is a schematic flowchart illustrating a method for preparing welding electrodes suitable for welding 650MPa-grade ultra-supercritical high-temperature steel, as provided in an embodiment of this application.

[0064] Please see Figure 1 This application provides a method for preparing welding electrodes, the method comprising:

[0065] The raw materials of the medicinal peel are mixed to obtain the first mixture;

[0066] The first mixture is mixed with the adhesive to obtain the second mixture;

[0067] The second mixture is coated onto the outside of the welding core to obtain a semi-finished welding electrode;

[0068] The semi-finished product is subjected to quasi-low temperature baking, low temperature baking, and high temperature baking to obtain welding rods.

[0069] In some embodiments, the binder is added in a mass fraction of 20% to 30% of the first mixture.

[0070] The proportion of the added adhesive to the mass of the first mixture is defined as: Added adhesive: Mass of the first mixture = 20% to 30%. For example, the proportion of the added adhesive to the mass of the first mixture can be 20%, 22%, 23%, 25%, 26%, 28%, 29%, 30%, etc.

[0071] In some embodiments, the quasi-low temperature baking temperature is 40℃~50℃, and the time is 2h~3h.

[0072] For example, the temperature of the quasi-low temperature baking can be 40℃, 41℃, 43℃, 44℃, 45℃, 47℃, 49℃, 50℃, etc.; and the time can be 2h, 2.2h, 2.5h, 2.8h, 3h, etc.

[0073] In some embodiments, the low-temperature baking temperature is 80°C to 100°C and the time is 4 hours to 5 hours.

[0074] For example, the low-temperature baking temperature is 80℃, 85℃, 90℃, 92℃, 95℃, 98℃, 100℃, etc.; and the time is 4h, 4.2h, 4.5h, 4.8h, 5h, etc.

[0075] In some embodiments, the high-temperature baking temperature is 380℃~400℃ and the time is 1h~2h.

[0076] For example, the high-temperature baking temperature is 380℃, 385℃, 390℃, 395℃, 400℃, etc.; the time is 1h, 1.2h, 1.4h, 1.6h, 1.8h, 2h, etc.

[0077] This application provides a cladding metal suitable for welding 650MPa grade ultra-supercritical high temperature steel.

[0078] In some embodiments, the chemical composition of the deposited metal, by mass fraction, includes:

[0079] C: 0.12%–0.16%, Mn: 0.60%–1.40%, Si: 0.01%–0.50%, Cr: 9.0%–11.0%, Mo: 1.40%–1.70%, V: 0.30%–0.40%, Nb: 0.04%–0.07%, N: 0.005%–0.02%, B: 0.005%–0.015%, Co: 0.80%–1.50%, Al: 0.0001%–0.005%, Ca: 0.0001%–0.005%, and Fe.

[0080] In some embodiments, the deposited metal satisfies at least one of the following properties: room temperature tensile strength of 650MPa to 800MPa, room temperature yield strength of 530MPa to 700MPa, room temperature elongation after fracture of 15% to 30%, impact strength at 20°C of 41J to 120J, and HB hardness of 180 to 350.

[0081] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0082] The welding rod core diameters involved in this application are typically 3.2 mm, 4.0 mm, and 5.0 mm. This patent details the manufacturing process of welding rods with a 5.0 mm core. The manufacturing processes for welding rods with diameters of 3.2 mm and 4.0 mm are the same as those for welding rods with a diameter of 5.0 mm. During the production of welding rods, it is necessary to use the corresponding mold inner diameter and pipe inner diameter according to the outer diameter of the core to ensure smooth production of welding rods.

[0083] Example 1

[0084] This embodiment provides a welding electrode suitable for welding 650MPa grade ultra-supercritical high-temperature steel, consisting of a core and a coating covering the surface of the core. The composition and content of the coating are as follows: magnesite: 40 parts by weight, fluorite: 32 parts by weight, dolomite: 3.5 parts by weight, ferrosilicon: 7 parts by weight, sodium titanate: 3 parts by weight, metallic chromium powder: 10 parts by weight, chromium oxide green: 0.3 parts by weight, aluminum-magnesium alloy: 0.2 parts by weight, and sodium alginate: 2 parts by weight.

[0085] The core wire diameter is 5.0 mm, and the length is machined to 400 mm. The chemical composition of the core wire is as follows: carbon 0.16%, manganese 1.10%, silicon 0.20%, chromium 8.0%, molybdenum 1.70%, vanadium 0.40%, niobium 0.07%, nitrogen 0.005%, boron 0.015%, cobalt 1.40%, and the remaining elements are iron and impurities.

[0086] Based on the chemical composition of the coating and core described above, this embodiment also provides a method for preparing a welding electrode suitable for welding 650MPa grade ultra-supercritical high-temperature steel. The method includes: mixing the coating raw materials for 20 minutes to obtain a first mixture; adding a binder equal to 25% of the total coating volume and mixing for 10 minutes to obtain a second mixture; feeding the second mixture into an oil pump to coat the core; baking at a near-low temperature of 45°C for 2.5 hours, a low temperature of 90°C for 4.5 hours, and then a high temperature of 390°C for 1.5 hours to obtain the welding electrode; after the high-temperature baking is completed, cooling the welding electrode to below 50°C and packaging it.

[0087] In the implementation of the welding control technology involved in this embodiment, the welding conditions are as follows: the welding test plate is prepared in accordance with the standard GB / T25774.1-2010 "Inspection of Welding Materials - Part 1: Preparation and Inspection of Mechanical Properties of Steel, Nickel and Nickel Alloy Deposited Metals". The thickness of the welding test plate is 20mm, the width is 150mm, and the length is 400mm. The preheating temperature of the test plate before welding is 150℃. The welding power source is DC reverse polarity, the welding current is 230A, the welding voltage is 28V, the welding speed is 150mm / min, and the interpass temperature during welding is 200-250℃. After the test plate is welded, it is cooled to room temperature and then the surface is polished to a smooth finish. After the test plate backing plate is processed, it is subjected to flaw detection.

[0088] The heat treatment and testing items for the welding control technology test plate involved in this embodiment include: heat treatment is tempering treatment, oil quenching at 1100℃ for 2 hours, oil cooling to below 180℃ followed by tempering at 730℃ for 12 hours and air cooling, with a heating rate of 50℃ / h for all stages. The testing items include chemical composition analysis, tensile testing, 20℃ impact testing, and HB hardness testing.

[0089] The composition of the cladding metal formed by welding in this embodiment, by mass fraction, is as follows: 0.12% carbon, 0.90% manganese, 0.25% silicon, 9.05% chromium, 1.6% molybdenum, 0.30% vanadium, 0.05% niobium, 0.02% nitrogen, 0.006% boron, 1.05% cobalt, 0.0006% aluminum, 0.0002% calcium, with the remainder being iron and impurities. Simultaneously, the cladding metal exhibits a room temperature tensile strength of 720 MPa, a room temperature yield strength of 600 MPa, a room temperature elongation at break of 19%, impact strengths of 70 J, 78 J, and 85 J at 20°C, and HB hardness of 210, 212, and 210.

[0090] Example 2

[0091] This embodiment provides a welding electrode suitable for welding 650MPa grade ultra-supercritical high-temperature steel, consisting of a core and a coating covering the surface of the core. The composition and content of the coating are as follows: magnesite: 41 parts by weight, fluorite: 33 parts by weight, dolomite: 4 parts by weight, ferrosilicon: 6 parts by weight, sodium titanate: 4 parts by weight, metallic chromium powder: 11 parts by weight, chromium oxide green: 0.3 parts by weight, aluminum-magnesium alloy: 0.2 parts by weight, and sodium alginate: 2 parts by weight.

[0092] The core wire diameter is 5.0 mm, and the length is machined to 400 mm. The chemical composition of the core wire is as follows: carbon 0.16%, manganese 1.10%, silicon 0.20%, chromium 8.0%, molybdenum 1.70%, vanadium 0.40%, niobium 0.07%, nitrogen 0.005%, boron 0.015%, cobalt 1.40%, and the remaining elements are iron and impurities.

[0093] Based on the chemical composition of the coating and core described above, this embodiment also provides a method for preparing a welding electrode suitable for welding 650MPa grade ultra-supercritical high-temperature steel. The method includes: mixing the coating raw materials for 20 minutes to obtain a first mixture; adding a binder equal to 25% of the total coating volume and mixing for 10 minutes to obtain a second mixture; feeding the second mixture into an oil pump to coat the core; baking at a near-low temperature of 45°C for 2.5 hours, a low temperature of 90°C for 4.5 hours, and then a high temperature of 390°C for 1.5 hours to obtain the welding electrode; after the high-temperature baking is completed, cooling the welding electrode to below 50°C and packaging it.

[0094] In the implementation of the welding control technology involved in this embodiment, the welding conditions are as follows: the welding test plate is prepared in accordance with the standard GB / T25774.1-2010 "Inspection of Welding Materials - Part 1: Preparation and Inspection of Mechanical Properties of Steel, Nickel and Nickel Alloy Deposited Metals". The thickness of the welding test plate is 20mm, the width is 150mm, and the length is 400mm. The preheating temperature of the test plate before welding is 150℃. The welding power source is DC reverse polarity, the welding current is 230A, the welding voltage is 28V, the welding speed is 150mm / min, and the interpass temperature during welding is 200-250℃. After the test plate is welded, it is cooled to room temperature and then the surface is polished to a smooth finish. After the test plate backing plate is processed, it is subjected to flaw detection.

[0095] The heat treatment and testing items for the welding control technology test plate involved in this embodiment include: heat treatment is tempering treatment, oil quenching at 1100℃ for 2 hours, oil cooling to below 180℃ followed by tempering at 730℃ for 12 hours and air cooling, with a heating rate of 50℃ / h for all stages. The testing items include chemical composition analysis, tensile testing, 20℃ impact testing, and HB hardness testing.

[0096] The composition of the cladding metal formed by welding in this embodiment, by mass fraction, is as follows: 0.11% carbon, 0.88% manganese, 0.23% silicon, 9.2% chromium, 1.6% molybdenum, 0.30% vanadium, 0.05% niobium, 0.02% nitrogen, 0.006% boron, 1.05% cobalt, 0.0006% aluminum, 0.0002% calcium, with the remainder being iron and impurities. The cladding metal has a room temperature tensile strength of 740 MPa, a room temperature yield strength of 615 MPa, a room temperature elongation after fracture of 20%, and impact strengths of 65 J, 60 J, and 66 J at 20°C, with HB hardnesses of 215, 220, and 221.

[0097] Example 3

[0098] The difference between this embodiment and Embodiment 2 lies in the welding scheme, which is as follows:

[0099] In the implementation of the welding control technology involved in this embodiment, the welding conditions are as follows: the welding test plate is prepared in accordance with the standard GB / T25774.1-2010 "Inspection of Welding Materials - Part 1: Preparation and Inspection of Mechanical Properties of Steel, Nickel and Nickel Alloy Deposited Metals". The thickness of the welding test plate is 20mm, the width is 150mm, and the length is 400mm. The preheating temperature of the test plate before welding is 150℃. The welding power source is DC reverse polarity, the welding current is 240A, the welding voltage is 28V, the welding speed is 120mm / min, and the interpass temperature during welding is 250-300℃. After the test plate is welded, it is cooled to room temperature and then the surface is polished to a smooth finish. After the test plate backing plate is processed, it is subjected to flaw detection.

[0100] The heat treatment and testing items for the welding control technology test plate involved in this embodiment include: heat treatment is tempering treatment, oil quenching at 1100℃ for 2 hours, oil cooling to below 180℃ followed by tempering at 730℃ for 12 hours and air cooling, with a heating rate of 50℃ / h for all stages. The testing items include chemical composition analysis, tensile testing, 20℃ impact testing, and HB hardness testing.

[0101] The composition of the cladding metal formed by welding in this embodiment, by mass fraction, is as follows: 0.10% carbon, 0.80% manganese, 0.20% silicon, 9.0% chromium, 1.55% molybdenum, 0.30% vanadium, 0.05% niobium, 0.025% nitrogen, 0.005% boron, 1.05% cobalt, 0.0005% aluminum, 0.0002% calcium, and the remaining elements are iron and impurity elements.

[0102] The room temperature tensile strength of the weld metal is 690 MPa, the room temperature yield strength is 580 MPa, the room temperature elongation after fracture is 22%, the impact strength at 20℃ is 75 J, 84 J, and 56 J, and the HB hardness is 208, 210, and 210.

[0103] Furthermore, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0104] In this embodiment of the invention, the welding electrode has moderate molten iron fluidity, stable and concentrated arc blowing force, good welding operation performance for welders and good mechanical properties of welds. It improves production efficiency while ensuring quality, can replace foreign welding electrodes, realize the localization of the welding electrode, reduce manufacturing plant costs and shorten procurement cycle. After its widespread use, welding electrode manufacturers can also increase sales revenue, generate profits for enterprises and drive employment.

[0105] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A flux coating for welding 650MPa grade ultra-supercritical high-temperature steel, characterized in that, The raw materials for the medicated coating are, by weight, as follows: Magnesia: 39-43 parts, Fluorite: 30-35 parts, Dolomite: 3-5 parts, Ferrosilicon: 5-10 parts, Sodium titanate: 2-5 parts, Metallic chromium powder: 10-15 parts, Chromium oxide green: 0.1-0.4 parts, Aluminum-magnesium alloy: 0.1-0.3 parts, Sodium alginate: 1.5-2.5 parts.

2. The medicated coating according to claim 1, characterized in that, The raw materials for the medicated coating are, by weight, as follows: Magnesia: 40 parts, Fluorite: 32 parts, Dolomite: 3.5 parts, Ferrosilicon: 7 parts, Sodium Titanate: 3 parts, Chromium Powder: 10 parts, Chromium Oxide Green: 0.3 parts, Aluminum-Magnesium Alloy: 0.2 parts, Sodium Alginate: 2 parts; or, Magnesia: 41 parts, Fluorite: 33 parts, Dolomite: 4 parts, Ferrosilicon: 6 parts, Sodium titanate: 4 parts, Chromium metal powder: 11 parts, Chromium oxide green: 0.3 parts, Aluminum-magnesium alloy: 0.2 parts, Sodium alginate: 2 parts.

3. The medicated coating according to claim 2, characterized in that, In the magnesia, the mass percentage of MgCO3 is ≥95%, the mass percentage of S is ≤0.01%, and the mass percentage of P is ≤0.02%; and / or, In the fluorite, the mass percentage of CaF2 is ≥98%, the mass percentage of SiO2 is ≤1.0%, the mass percentage of C is ≤0.05%, the mass percentage of S is ≤0.01%, and the mass percentage of P is ≤0.02%; and / or, In the dolomite, the mass percentage of CaCO3 is ≥50%, the mass percentage of MgCO3 is ≥40%, the mass percentage of S is ≤0.03%, and the mass percentage of P is ≤0.03%; and / or, In the ferrosilicon, the mass percentage of Si is 42%~47%, the mass percentage of S is ≤0.02%, the mass percentage of P is ≤0.03%, and the mass percentage of C is ≤0.05%; and / or, In the sodium titanate, the mass percentage of TiO2 is ≥72%, the mass percentage of Na2O is ≥16%, the mass percentage of S is ≤0.02%, and the mass percentage of P is ≤0.03%; and / or, In the chromium powder, the mass percentage of Cr is ≥99.9%; and / or, In the aluminum-magnesium alloy, the sum of the mass percentages of Al and Mg is ≥97.5%, and the mass percentage of Al is 47%~53%.

4. The medicated coating according to claim 3, characterized in that, The particle size requirements for the magnesite are: 100% by mass of -40 mesh and ≤60% by mass of -150 mesh; and / or, The particle size requirements for the fluorite are: 100% by mass of -40 mesh and ≤60% by mass of -150 mesh; and / or, The dolomite particle size requirements are: -40 mesh ≤ 100% by mass, -150 mesh ≤ 60% by mass; and / or, The particle size requirement for the ferrosilicon is: -40 mesh accounts for 100% by mass; and / or, The sodium titanate particle size requirement is: -80 mesh ≥ 95% by mass; and / or, The particle size requirement for the chromium powder is: -60 mesh, accounting for 100% by mass; and / or, The particle size requirement for the aluminum-magnesium alloy is: -80 mesh ≥ 95% by mass.

5. A welding electrode for welding 650MPa grade ultra-supercritical high-temperature steel, characterized in that, The welding electrode includes a core and a coating, the coating covering the core, and the coating being the coating described in any one of claims 1 to 4; wherein, if the diameter of the welding electrode is 4.0 mm, the maximum working current of the welding electrode is 200 A; if the diameter of the welding electrode is 5.0 mm, the maximum working current of the welding electrode is 240 A.

6. The welding electrode according to claim 5, characterized in that, The chemical composition of the welding core, expressed as a mass fraction, is as follows: C: 0.13%~0.16%, Mn: 0.70%~1.40%, Si: 0.10%~0.30%, Cr: 7.0%~8.0%, Mo: 1.50%~1.70%, V: 0.30%~0.40%, Nb: 0.05%~0.07%, N: 0.005%~0.01%, B: 0.007%~0.015%, Co: 0.90%~1.50%, balance Fe.

7. A method for preparing the welding electrode as described in claim 5 or 6, characterized in that, The method includes: The raw materials of the medicinal peel are mixed to obtain the first mixture; The first mixture is mixed with the adhesive to obtain the second mixture; The second mixture is coated onto the outside of the welding core to obtain a semi-finished welding electrode; The semi-finished product is subjected to quasi-low temperature baking, low temperature baking, and high temperature baking to obtain welding rods.

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