Q500qenh flux-cored wire for welding of bridges

Abstract

The application provides a Q500qENH coating-free bridge welding electrode, a coating and a deposited metal, and belongs to the field of welding materials.The coating raw material comprises, by weight fraction, 30-35 parts of carbonates, 20-25 parts of fluorides, 4-7.5 parts of rutile, 2-5 parts of silicon dioxide, 3-6 parts of electrolytic manganese, 8-11 parts of ferrosilicon, 1-3 parts of nickel, 1-3 parts of metallic chromium, 0.5-1.0 parts of copper, 15-20 parts of iron powder, 0.5-1.0 parts of soda ash, 0.5-1.0 parts of sodium alginate and 0.10-0.15 parts of graphite.Through the organic combination of the coating raw material, the normal-temperature deposited metal formed after the electrode is welded has a tensile strength of greater than or equal to 630 Mpa, a yield strength of greater than or equal to 500 Mpa, an elongation of greater than or equal to 18%, an I value of greater than 6.5 and an impact at -40 DEG C of greater than or equal to 60 J.

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 Q500qENH uncoated bridge welding. Background Technology

[0002] In the United States, construction of unpainted weathering steel bridges began in 1964, with approximately 45% of steel bridges now constructed using this material. Currently, there are over 23,000 unpainted weathering steel bridges in the US. Japan began constructing unpainted weathering steel bridges in 1967, and now over 20% of its steel bridges are made of this material. The widespread use of steel in bridge construction is a superior strategy for fully utilizing the reusability of steel and achieving sustainable development. Furthermore, the selection of unpainted weathering steel is a crucial step in promoting green building and building materials, aligning with national development strategies. Currently, conventional bridge steel is used for steel trusses, requiring painting and repainting every few years. The painting process and the inevitable peeling of the original paint film can pollute reservoirs and water sources. The use of unpainted steel avoids the environmental pollution caused by painting and repainting, effectively addressing the protection of reservoir water sources.

[0003] Welding materials for unpainted bridges need to withstand harsh environments such as large temperature differences and strong ultraviolet radiation, while also considering weldability, mechanical properties, and low-temperature toughness. Currently, there are no suitable welding materials for unpainted bridges, especially for 500MPa grade bridge steel Q500qENH. Therefore, how to improve the weldability of welding materials for unpainted bridges while ensuring high weather resistance 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 Q500qENH uncoated bridge welding, in order to solve the technical problem that existing welding materials are difficult to improve welding performance while ensuring high weather resistance.

[0005] In a first aspect, this application provides a coating for uncoated bridge welding, wherein the raw materials of the coating comprise, by weight:

[0006] Carbonates: 30-35 parts, fluorides: 20-25 parts, rutile: 4-7.5 parts, silicon dioxide: 2-5 parts, electrolytic manganese: 3-6 parts, ferrosilicon: 8-11 parts, nickel: 1-3 parts, metallic chromium: 1-3 parts, copper: 0.5-1.0 parts, iron powder: 15-20 parts, soda ash: 0.5-1.0 parts, sodium alginate: 0.5-1.0 parts, graphite: 0.10-0.15 parts.

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

[0008] Carbonates: 30 parts, fluorides: 24 parts, rutile: 5 parts, silicon dioxide: 4 parts, electrolytic manganese: 5 parts, ferrosilicon: 8 parts, nickel: 1.5 parts, metallic chromium: 1.5 parts, copper: 0.8 parts, iron powder: 18 parts, soda ash: 0.5 parts, sodium alginate: 0.8 parts, graphite: 0.1 parts; or,

[0009] Carbonates: 30 parts, fluorides: 24 parts, rutile: 5 parts, silicon dioxide: 4 parts, electrolytic manganese: 5 parts, ferrosilicon: 8 parts, nickel: 2 parts, metallic chromium: 1.5 parts, copper: 1.0 part, iron powder: 16 parts, soda ash: 0.5 parts, sodium alginate: 0.8 parts, graphite: 0.1 parts by weight; or,

[0010] Carbonates: 30 parts, fluorides: 24 parts, rutile: 5 parts, silicon dioxide: 4 parts, electrolytic manganese: 5 parts, ferrosilicon: 8 parts, nickel: 1.5 parts, metallic chromium: 1.8 parts, copper: 0.8 parts, iron powder: 18 parts, soda ash: 0.5 parts, sodium alginate: 0.8 parts, graphite: 0.1 parts.

[0011] Optionally, in the carbonate, the mass percentage of CaCO3 is ≥96%, the mass percentage of S is ≤0.03%, and the mass percentage of P is ≤0.03%; and / or,

[0012] In the fluoride, the mass percentage of CaF2 is ≥96%, the mass percentage of SiO2 is ≤3.0%, the mass percentage of C is ≤0.08%, the mass percentage of S is ≤0.03%, and the mass percentage of P is ≤0.03%; and / or,

[0013] In the rutile, the mass percentage of TiO2 is ≥96%, the mass percentage of S is ≤0.03%, and the mass percentage of P is ≤0.03%; and / or,

[0014] In the silicon dioxide, the mass percentage of Si is 42%–47%, the mass percentage of C is ≤0.50%, the mass percentage of S is ≤0.020%, and the mass percentage of P is ≤0.040%; and / or,

[0015] In the electrolytic manganese, the mass percentage of Mn is ≥99.5%, the mass percentage of C is ≤0.08%, the mass percentage of S is ≤0.10%, the mass percentage of P is ≤0.010%, and the sum of the mass percentages of Se, Si, and Fe is ≤0.310%; and / or,

[0016] In the iron powder, the mass percentage of Fe is ≥97%, the mass percentage of Si is ≤0.20%, the mass percentage of C is ≤0.10%, the mass percentage of S is ≤0.020%, and the mass percentage of P is ≤0.020%; and / or,

[0017] In the soda ash, the mass percentage of Na₂CO₃ is ≥99%, and the mass percentage of NaCl is ≤0.7%; and / or,

[0018] In the sodium alginate, the mass percentage of Na₂O is 9.5%–13.0%, and the mass percentage of P is ≤0.050%; and / or,

[0019] In the graphite, the mass percentage of fixed carbon is ≥90.0%, and the mass percentage of S is ≤0.05%.

[0020] Optionally, the particle size requirements for the carbonate are: 100% by mass of -30 mesh, ≥97% by mass of -40 mesh, and ≤70% by mass of -170 mesh; and / or,

[0021] The particle size requirements for the fluoride are: 100% by mass of -30 mesh, ≥97% by mass of -40 mesh, and ≤70% by mass of -170 mesh; and / or,

[0022] The rutile particle size requirements are: -40 mesh ≥ 100% by mass, -160 mesh ≤ 30% by mass; and / or,

[0023] The particle size requirements for the silica are: 100% by mass of -30 mesh, ≥98% by mass of -40 mesh, and ≤20% by mass of -200 mesh; and / or,

[0024] The particle size requirements for the electrolytic manganese are: -30 mesh ≥ 100% by mass, -40 mesh ≥ 98% by mass, and -170 mesh ≤ 50% by mass; and / or,

[0025] The loose bulk density of the iron powder is 2.9 g / cm³. 3 ~3.1g / cm 3 The particle size requirements are: -30 mesh ≥ 100% by mass, -40 mesh ≥ 98% by mass, and -170 mesh ≤ 20% by mass; and / or,

[0026] The particle size requirements for the soda ash are: -30 mesh ≥ 100% by mass, -40 mesh ≥ 98% by mass; and / or,

[0027] The sodium alginate has an ash content of 20.0% to 30.0%, and the particle size requirement is: 100% by mass of -100 mesh; and / or,

[0028] The weight loss rate of the graphite is ≤2.0%, and the particle size requirement is: -200 mesh accounts for 100% of the mass.

[0029] Secondly, this application provides a coating-free welding electrode for bridge welding, the welding electrode comprising a low-sulfur-phosphorus core and a flux coating, the flux coating covering the outside of the low-sulfur-phosphorus core, the flux coating being the flux coating described in any embodiment of the first aspect, the low-sulfur-phosphorus core being an H08GX(L) core wire rod, the diameter deviation of the H08GX(L) core wire rod being ≤0.4mm, and the ellipticity of the wire rod being ≤0.5mm.

[0030] Optionally, the chemical composition of the H08GX(L) welding core wire rod, expressed as a mass fraction, is as follows:

[0031] C≤0.10%, Mn: 0.30%~0.55%, Si≤0.08%, S≤0.0045%, P≤0.008%, Ni≤0.30%, Cr≤0.10%, Cu≤0.20%, As≤0.007%, Al≤0.030%, with the balance being Fe and unavoidable impurities.

[0032] Thirdly, this application provides a method for preparing the uncoated bridge welding electrode according to any embodiment of the second aspect, the method comprising:

[0033] The raw materials of the herb peel are mixed to obtain the first mixture;

[0034] The first mixture was wet-mixed with water glass in a potassium-sodium molar ratio of 1:1 to obtain the second mixture.

[0035] The second mixture is coated onto the outside of a low-sulfur-phosphorus welding core and then baked to obtain a welding electrode.

[0036] Optionally, the water glass is added in a mass fraction of 21% to 23% of the first mixture, and the water glass has a Baumé density of 41Be to 42Be.

[0037] Fourthly, this application provides a cladding metal for uncoated bridge welding, wherein the cladding metal is prepared by welding rods as described in any one embodiment of the second aspect during the welding process; wherein the cladding metal satisfies at least one of the following properties: tensile strength ≥630 MPa, yield strength ≥500 MPa, elongation ≥18%, I value >6.5, and impact at -40℃ ≥60 J.

[0038] Optionally, the chemical composition of the cladding metal, expressed as a mass fraction, is as follows:

[0039] C: 0.050%–0.055%, Mn: 1.40%–1.48%, Si: 0.30%–0.35%, S≤0.005%, P≤0.008%, Cr: 0.45%–0.60%, Ni: 0.60%–0.70%, Mo: 0.08%–0.09%, V: 0.003%–0.005%, Cu: 0.30%–0.35%, with the balance being Fe and unavoidable impurities.

[0040] The technical solutions provided in this application have the following advantages compared with the prior art:

[0041] This application provides a coating for Q500qENH uncoated bridge welding. The coating's raw materials are rationally designed, organically combining carbonates, fluorides, alloys, rutile, and substances that improve pressure coating. The resulting weld metal at room temperature exhibits a tensile strength ≥630 MPa, a yield strength ≥500 MPa, an elongation ≥18%, an I-value >6.5, and an impact resistance ≥60 J at -40℃. The electrode exhibits excellent manufacturing process performance, a stable arc with minimal spatter, good slag removal, and aesthetically pleasing weld formation. Appropriate control of alloying elements in the weld metal results in excellent mechanical properties, effectively improving the weldability of the welding material. Attached Figure Description

[0042] 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.

[0043] 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.

[0044] Figure 1 A schematic flowchart illustrating the preparation method of the Q500qENH uncoated bridge welding electrode provided in this application embodiment. Detailed Implementation

[0045] 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.

[0046] 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.

[0047] 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, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0048] 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.

[0049] This application provides a coating for uncoated bridge welding, wherein the raw materials of the coating, by weight, include: carbonate: 30-35 parts, fluoride: 20-25 parts, rutile: 4-7.5 parts, silicon dioxide: 2-5 parts, electrolytic manganese: 3-6 parts, ferrosilicon: 8-11 parts, nickel: 1-3 parts, metallic chromium: 1-3 parts, copper: 0.5-1.0 parts, iron powder: 15-20 parts, soda ash: 0.5-1.0 parts, sodium alginate: 0.5-1.0 parts, and graphite: 0.10-0.15 parts.

[0050] To facilitate understanding of the invention, the main functions of each component of the medicinal peel raw material of the present invention are explained as follows:

[0051] Carbonates: Carbonates are used in welding electrodes. Under the heat of the electric arc, they decompose into CaO and CO2. They are commonly used slag-building and gas-generating materials in electrode manufacturing, increasing slag basicity, stabilizing the arc, increasing the interfacial tension and surface tension between the slag and the metal, improving slag removal, and having good desulfurization ability. For example, the content of the carbonate iron powder can be 30 parts, 30.5 parts, 31 parts, 32 parts, 32.5 parts, 33 parts, 34 parts, 34.5 parts, 35 parts, etc.

[0052] Fluorides: Fluorides adjust the melting point and viscosity of slag, increase its fluidity, and improve its physical properties, playing a crucial role in weld formation and slag removal. They are also a major material for reducing diffusible hydrogen in the weld. However, the presence of fluoride can cause arc instability and produce toxic gases. For example, the content of the fluoride iron powder can be 20 parts, 21 parts, 22 parts, 22.5 parts, 23 parts, 24 parts, 24.5 parts, 25 parts, etc.

[0053] Rutile: Its main functions in welding electrodes are slag building and arc stabilization. In this invention, the addition of the above-mentioned amount of rutile plays a crucial role in weld formation. For example, the content of the rutile iron powder can be 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, etc.

[0054] Silica: Adjusting the Si content in the weld metal improves welding process performance but deteriorates mechanical properties, so its addition amount needs to be controlled. In this invention, the addition amount of ferrosilicon is 6% to 8%, and should be controlled as low as possible. For example, the content of the ferrosilicon powder can be 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, etc.

[0055] Iron powder: Iron powder is a major component of carbon steel. Its addition improves the deposition efficiency of welding electrodes, enhances welding process performance, and also plays a role in stabilizing the electric arc. For example, the content of the iron powder can be 15 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 19 parts, 19.5 parts, 20 parts, etc.

[0056] Electrolytic manganese: Its addition can desulfurize and deoxidize the weld, and also transfer manganese elements to the weld, thereby improving the weld strength. For example, the content of the electrolytic manganese iron powder can be 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, etc.

[0057] Ferrosilicon: Silicon is an important deoxidizer and also an important alloying agent for weld metal. Silicon can reduce the oxygen content of weld metal and improve its impact toughness, but too high a content has the opposite effect. Using a combination of silicon and manganese for deoxidation yields better results. For example, the content of the ferrosilicon powder can be 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, etc.

[0058] Graphite: Carbon (C) is an element that must be strictly controlled in carbon steel and low-alloy steel. It can significantly improve the strength of the weld metal, but adding too much will affect the toughness of the weld metal. For example, the content of the graphite iron powder can be 0.10 parts, 0.11 parts, 0.12 parts, 0.13 parts, 0.14 parts, 0.15 parts, etc.

[0059] Soda ash and sodium alginate: Soda ash and sodium alginate are added to ensure production and improve coating performance. For example, the content of iron powder in the soda ash can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, etc.; the content of iron powder in the sodium alginate can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, etc.

[0060] Nickel, chromium, and copper: Nickel acts as an inoculant, refining grains, reducing segregation, and promoting the formation of acicular ferrite, thereby improving the toughness of ferrite. Nickel also increases dislocation energy, promotes cross-slip of spiral dislocations at low temperatures, increases the energy consumed in crack propagation, and also improves toughness. Ni, along with Cr and Cu, has corrosion-resistant properties. It is mainly derived from metallic nickel. For example, the nickel content can be 1 part, 1.5 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, or 3 parts; the chromium content can be 1 part, 1.5 parts, 1.8 parts, 2.0 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, or 3 parts; and the copper content can be 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, or 1.0 parts.

[0061] In some embodiments, the raw materials of the coating, by weight, include: carbonate: 30 parts, fluoride: 24 parts, rutile: 5 parts, silicon dioxide: 4 parts, electrolytic manganese: 5 parts, ferrosilicon: 8 parts, nickel: 1.5 parts, metallic chromium: 1.5 parts, copper: 0.8 parts, iron powder: 18 parts, soda ash: 0.5 parts, sodium alginate: 0.8 parts, graphite: 0.1 parts; or, carbonate: 30 parts, fluoride: 24 parts, rutile: 5 parts, silicon dioxide: 4 parts, electrolytic manganese: 5 parts. 8 parts by weight of ferrosilicon, 2 parts by weight of nickel, 1.5 parts by weight of metallic chromium, 1.0 part by weight of copper, 16 parts by weight of iron powder, 0.5 parts by weight of soda ash, 0.8 parts by weight of sodium alginate, and 0.1 parts by weight of graphite; or 30 parts by weight of carbonate, 24 parts by weight of fluoride, 5 parts by weight of rutile, 4 parts by weight of silicon dioxide, 5 parts by weight of electrolytic manganese, 8 parts by weight of ferrosilicon, 1.5 parts by weight of nickel, 1.8 parts by weight of metallic chromium, 0.8 parts by weight of copper, 18 parts by weight of iron powder, 0.5 parts by weight of soda ash, 0.8 parts by weight of sodium alginate, and 0.1 parts by weight of graphite.

[0062] In some embodiments, the carbonate contains ≥96% CaCO3, ≤0.03% S, and ≤0.03% P by mass; the fluoride contains ≥96% CaF2, ≤3.0% SiO2, ≤0.08% C, ≤0.03% S, and ≤0.03% P by mass; the rutile contains ≥96% TiO2, ≤0.03% S, and ≤0.03% P by mass; the silicon dioxide contains 42%–47% Si, ≤0.50% C, ≤0.020% S, and ≤0.040% P by mass; and the electrolytic manganese contains Mn by mass... The composition of the graphite is as follows: ≥99.5% by mass, C ≤0.08% by mass, S ≤0.10% by mass, P ≤0.010% by mass, and the sum of the mass percentages of Se, Si, and Fe ≤0.310%; In the iron powder, Fe ≥97% by mass, Si ≤0.20% by mass, C ≤0.10% by mass, S ≤0.020% by mass, and P ≤0.020% by mass; In the soda ash, Na₂CO₃ ≥99% by mass and NaCl ≤0.7% by mass; In the sodium alginate, Na₂O 9.5%–13.0% by mass and P ≤0.050% by mass; In the graphite, fixed carbon ≥90.0% by mass and S ≤0.05% by mass.

[0063] In some embodiments, the particle size requirements for the carbonates are: 100% by mass of -30 mesh, ≥97% by mass of -40 mesh, and ≤70% by mass of -170 mesh; the particle size requirements for the fluorides are: 100% by mass of -30 mesh, ≥97% by mass of -40 mesh, and ≤70% by mass of -170 mesh; the particle size requirements for the rutile are: ≥100% by mass of -40 mesh and ≤30% by mass of -160 mesh; the particle size requirements for the silica are: 100% by mass of -30 mesh, ≥98% by mass of -40 mesh, and ≤20% by mass of -200 mesh; the particle size requirements for the electrolytic manganese are: 100% by mass of -30 mesh, ≥98% by mass of -40 mesh, and ≤50% by mass of -170 mesh; and the loose packing density of the iron powder is 2.9 g / cm³. 3 ~3.1g / cm 3 The particle size requirements are as follows: -30 mesh ≥ 100% by mass, -40 mesh ≥ 98% by mass, and -170 mesh ≤ 20% by mass; the particle size requirements for the soda ash are: -30 mesh ≥ 100% by mass and -40 mesh ≥ 98% by mass; the ash content of the sodium alginate is 20.0%–30.0%, and the particle size requirement is: -100% by mass of the -100 mesh; the weight loss rate of the graphite is ≤ 2.0%, and the particle size requirement is: -200 mesh ≥ 100% by mass.

[0064] This application provides a coating-free welding electrode for bridge welding, the electrode comprising a low-sulfur-phosphorus core and a flux coating, the flux coating covering the outside of the low-sulfur-phosphorus core.

[0065] The welding electrode prepared in this application is suitable for welding unpainted bridges, especially for welding Q500qENH unpainted bridges.

[0066] In some embodiments, the low-sulfur phosphorus welding core is an H08GX(L) welding core wire rod, wherein the diameter deviation of the H08GX(L) welding core wire rod is ≤0.4mm and the ellipticity of the wire rod is ≤0.5mm.

[0067] H08GX(L) wire rod is a high-quality H08GX wire rod with lower S and P content than ordinary H08GX wire rod, ensuring that the S content in the deposited metal is less than 0.005% and the P content is less than 0.01%. For example, the diameter deviation can be 0, 0.1mm, 0.15mm, 0.20mm, 0.25mm, 0.30mm, 0.35mm, 0.4mm, etc.; the ellipticity of the wire rod can be 0.05mm, 0.1mm, 0.15mm, 0.20mm, 0.25mm, 0.30mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, etc.

[0068] In some embodiments, the chemical composition of the H08GX(L) welding core wire rod, by mass fraction, is: C≤0.10%, Mn: 0.30%~0.55%, Si≤0.08%, S≤0.0045%, P≤0.008%, Ni≤0.30%, Cr≤0.10%, Cu≤0.20%, As≤0.007%, Al≤0.030%, with the balance being Fe and unavoidable impurities.

[0069] H08GX(L) wire rod is a high-quality H08GX wire rod with lower S and P content than ordinary H08GX wire rod, guaranteeing that the S content in the deposited metal is <0.005% and the P content is <0.01%. For example, the C content can be 0.01%, 0.02%, 0.04%, 0.05%, 0.07%, 0.08%, 0.09%, 0.10%, etc.; the Mn content can be 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, etc.; and the Si content can be 0.01%, 0.02%, 0.04%. The content of sulfur (S) can be 0.0005%, 0.0010%, 0.0015%, 0.0020%, 0.0025%, 0.0035%, 0.0045%, etc.; the content of phosphorus (P) can be 0.002%, 0.003%, 0.005%, 0.006%, 0.007%, 0.008%. The content of Ni can be 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, etc.; the content of Cr can be 0.02%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, etc.; the content of Cu can be 0.05%, 0.08%, 0.10%, 0.12%, 0.14%, 0.16%, 0.18%, 0.20%, etc.; the content of As can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, etc.; and the content of Al can be 0.010%, 0.015%, 0.020%, 0.025%, 0.030%, etc.

[0070] Figure 1 This is a schematic flowchart illustrating a method for preparing a coating-free welding electrode for bridge welding, as provided in an embodiment of this application.

[0071] Please see Figure 1 This application provides a method for preparing a coating-free welding electrode for bridge welding, the method comprising:

[0072] S1. Mix the raw materials of the herb peel to obtain the first mixture;

[0073] S2. The first mixture is wet-mixed with water glass in a potassium-sodium molar ratio of 1:1 to obtain the second mixture;

[0074] S3. The second mixture is coated onto the outside of the low-sulfur-phosphorus welding core and then baked to obtain the welding electrode.

[0075] In some embodiments, the water glass is added at a mass fraction of 21% to 23% of the mass of the first mixture, and the water glass has a Baumé density of 41Be to 42Be.

[0076] The mass fraction of water glass added relative to the mass of the first mixture is 21% to 23% (mass of water glass added: mass of the first mixture). For example, the mass fraction of water glass added relative to the mass of the first mixture can be 21%, 21.5%, 22%, 22.5%, 23%, etc.; the Baumé density of the water glass can be 41Be, 41.2Be, 41.4Be, 41.5Be, 41.7Be, 41.9Be, 42Be, etc.

[0077] Fourthly, this application provides a cladding metal for uncoated bridge welding, wherein the cladding metal is prepared by welding rods as described in any one embodiment of the second aspect during the welding process; wherein the cladding metal satisfies at least one of the following properties: tensile strength ≥630 MPa, yield strength ≥500 MPa, elongation ≥18%, I value >6.5, and impact at -40℃ ≥60 J.

[0078] In some embodiments, the chemical composition of the cladding metal, by mass fraction, is: C: 0.050%–0.055%, Mn: 1.40%–1.48%, Si: 0.30%–0.35%, S≤0.005%, P≤0.008%, Cr: 0.45%–0.60%, Ni: 0.60%–0.70%, Mo: 0.08%–0.09%, V: 0.003%–0.005%, Cu: 0.30%–0.35%, with the balance being Fe and unavoidable impurities.

[0079] By properly controlling the alloying elements in the weld metal, various mechanical properties are good, effectively improving the welding performance of the welding material. For example, the content of C can be 0.050%, 0.051%, 0.052%, 0.053%, 0.054%, 0.055%, etc.; the content of Mn can be 1.40%, 1.41%, 1.42%, 1.43%, 1.44%, 1.45%, 1.46%, 1.47%, 1.48%, etc.; the content of Si can be 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, etc.; the content of S can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, etc.; and the content of P can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, etc. The content of Cr can be 0.45%, 0.48%, 0.50%, 0.52%, 0.55%, 0.58%, 0.60%, etc.; the content of Ni can be 0.60%, 0.62%, 0.64%, 0.66%, 0.68%, 0.70%, etc.; the content of Mo can be 0.08%, 0.082%, 0.084%, 0.086%, 0.088%, 0.09%, etc.; the content of V can be 0.003%, 0.004%, 0.005%, etc.; the content of Cu can be 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, etc.

[0080] 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.

[0081] Example 1

[0082] This embodiment provides a welding electrode suitable for uncoated bridge welding of Q500qENH, which consists of a core and a coating covering the surface of the core. The coating material used in the welding electrode is mainly composed of carbonates, fluorides and alloys, with a small amount of rutile and substances that improve pressure coating.

[0083] The components and their weight percentages of the coating are as follows: 30 parts carbonate, 24 parts fluoride, 5 parts rutile, 4 parts silicon dioxide, 5 parts electrolytic manganese, 8 parts ferrosilicon, 1.5 parts nickel, 1.5 parts metallic chromium, 0.8 parts copper, 18 parts iron powder, 0.5 parts soda ash, 0.8 parts sodium alginate, and 0.1 parts graphite.

[0084] Based on the raw materials of the coating, this embodiment also provides a method for preparing a welding electrode suitable for Q500qENH uncoated bridge welding, the method comprising:

[0085] The above-mentioned coating materials were mixed evenly to obtain a first mixture; water glass with a potassium-to-sodium ratio of 1:1 and a Baumé density of 41Be at 20°C was added at 22 wt% of the first mixture for wet mixing. Wet electrodes were prepared using a dedicated H08GX(L) welding core on a hydraulic electrode production machine.

[0086] The composition of the weld metal after welding, by mass fraction, is as follows: C: 0.054%, Mn: 1.42%, Si: 0.34%, S: 0.0041%, P: 0.0075%, Cr: 0.46%, Ni: 0.63%, Mo: 0.087%, V: 0.0035%, Cu: 0.31%, with the balance being Fe and unavoidable impurities. The weld metal exhibits a tensile strength of 653 MPa, a yield strength of 578 MPa, an elongation of 26.0%, an average impact strength of 127 J at -40℃, and an I value of 7.02.

[0087] Example 2

[0088] The difference between this embodiment and Example 1 is that the components of the drug coating and their weight parts are as follows: 30 parts carbonate, 24 parts fluoride, 5 parts rutile, 4 parts silicon dioxide, 5 parts electrolytic manganese, 8 parts ferrosilicon, 2 parts nickel, 1.5 parts metallic chromium, 1.0 part copper, 16 parts iron powder, 0.5 parts soda ash, 0.8 parts sodium alginate, and 0.1 parts graphite.

[0089] The composition of the weld metal after welding is as follows: C: 0.052%, Mn: 1.46%, Si: 0.32%, S: 0.0043%, P: 0.0071%, Cr: 0.48%, Ni: 0.68%, Mo: 0.084%, V: 0.0045%, Cu: 0.35%, with the balance being Fe and unavoidable impurities. The weld metal exhibits a tensile strength of 663 MPa, a yield strength of 584 MPa, an elongation of 26.5%, an average impact strength of 117 J at -40℃, and an I value of 7.05.

[0090] Example 3

[0091] The difference between this embodiment and Embodiment 1 is that the components of the drug coating and their weight parts are as follows: 30 parts carbonate, 24 parts fluoride, 5 parts rutile, 4 parts silicon dioxide, 5 parts electrolytic manganese, 8 parts ferrosilicon, 1.5 parts nickel, 1.8 parts metallic chromium, 0.8 parts copper, 18 parts iron powder, 0.5 parts soda ash, 0.8 parts sodium alginate, and 0.1 parts graphite.

[0092] The composition of the weld metal after welding is as follows: C: 0.051%, Mn: 1.45%, Si: 0.32%, S: 0.0049%, P: 0.0063%, Cr: 0.58%, Ni: 0.64%, Mo: 0.084%, V: 0.0030%, Cu: 0.32%, with the balance being Fe and unavoidable impurities. The weld metal exhibits a tensile strength of 683 MPa, a yield strength of 591 MPa, an elongation of 25.0%, an average impact strength of 111 J at -40℃, and an I value of 7.14.

[0093] The Q500qENH uncoated bridge welding electrode (implemented in steps 1-3) exhibits stable arc, minimal spatter, good slag removal, excellent all-position welding performance, aesthetically pleasing weld formation, and moderate weld bead height when used with DC reverse polarity welding. The weld metal at room temperature has a tensile strength ≥630 MPa, yield strength ≥500 MPa, elongation ≥18%, I-value greater than 6.5, and impact resistance ≥60 J at -40℃.

[0094] Furthermore, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0095] In this embodiment of the invention, the electrode arc is stable, with minimal spatter, good slag removal, aesthetically pleasing weld beads, and excellent all-position operation performance. The electrode combines the weldability, mechanical properties, low-temperature toughness, and weather resistance of the welding materials.

[0096] 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 Q500qENH uncoated bridge welding electrode, characterized in that, The welding electrode includes a low-sulfur-phosphorus core and a coating, wherein the coating covers the outside of the low-sulfur-phosphorus core. The raw materials of the medicated skin, by weight, include: Carbonates: 30-35 parts, fluorides: 20-25 parts, rutile: 4-7.5 parts, silicon dioxide: 2-5 parts, electrolytic manganese: 3-6 parts, ferrosilicon: 8-11 parts, nickel: 1-3 parts, metallic chromium: 1-3 parts, copper: 0.5-1.0 parts, iron powder: 15-20 parts, soda ash: 0.5-1.0 parts, sodium alginate: 0.5-1.0 parts, graphite: 0.10-0.15 parts; The low-sulfur phosphorus welding core is an H08GX(L) welding core wire rod, and the diameter deviation of the H08GX(L) welding core wire rod is ≤0.4mm, and the ellipticity of the wire rod is ≤0.5mm. The chemical composition of the H08GX(L) welding core wire rod, expressed as a mass fraction, is as follows: C≤0.10%, Mn: 0.30%~0.55%, Si≤0.08%, S≤0.0045%, P≤0.008%, Ni≤0.30%, Cr≤0.10%, Cu≤0.20%, As≤0.007%, Al≤0.030%, with the balance being Fe and unavoidable impurities.

2. The welding electrode according to claim 1, characterized in that, The raw materials for the medicated coating are, by weight, as follows: Carbonates: 30 parts, fluorides: 24 parts, rutile: 5 parts, silicon dioxide: 4 parts, electrolytic manganese: 5 parts, ferrosilicon: 8 parts, nickel: 1.5 parts, metallic chromium: 1.5 parts, copper: 0.8 parts, iron powder: 18 parts, soda ash: 0.5 parts, sodium alginate: 0.8 parts, graphite: 0.1 parts; or, Carbonates: 30 parts, fluorides: 24 parts, rutile: 5 parts, silicon dioxide: 4 parts, electrolytic manganese: 5 parts, ferrosilicon: 8 parts, nickel: 2 parts, metallic chromium: 1.5 parts, copper: 1.0 part, iron powder: 16 parts, soda ash: 0.5 parts, sodium alginate: 0.8 parts, graphite: 0.1 parts; or, Carbonates: 30 parts, fluorides: 24 parts, rutile: 5 parts, silicon dioxide: 4 parts, electrolytic manganese: 5 parts, ferrosilicon: 8 parts, nickel: 1.5 parts, metallic chromium: 1.8 parts, copper: 0.8 parts, iron powder: 18 parts, soda ash: 0.5 parts, sodium alginate: 0.8 parts, graphite: 0.1 parts.

3. The welding electrode according to claim 2, characterized in that, In the carbonate, the mass percentage of CaCO3 is ≥96%, the mass percentage of S is ≤0.03%, and the mass percentage of P is ≤0.03%; and / or, In the fluoride, the mass percentage of CaF2 is ≥96%, the mass percentage of SiO2 is ≤3.0%, the mass percentage of C is ≤0.08%, the mass percentage of S is ≤0.03%, and the mass percentage of P is ≤0.03%; and / or, In the rutile, the mass percentage of TiO2 is ≥96%, the mass percentage of S is ≤0.03%, and the mass percentage of P is ≤0.03%; and / or, In the silicon dioxide, the mass percentage of Si is 42%~47%, the mass percentage of C is ≤0.50%, the mass percentage of S is ≤0.020%, and the mass percentage of P is ≤0.040%; and / or, In the electrolytic manganese, the mass percentage of Mn is ≥99.5%, the mass percentage of C is ≤0.08%, the mass percentage of S is ≤0.10%, the mass percentage of P is ≤0.010%, and the sum of the mass percentages of Se, Si, and Fe is ≤0.310%; and / or, In the iron powder, the mass percentage of Fe is ≥97%, the mass percentage of Si is ≤0.20%, the mass percentage of C is ≤0.10%, the mass percentage of S is ≤0.020%, and the mass percentage of P is ≤0.020%; and / or, In the soda ash, the mass percentage of Na₂CO₃ is ≥99%, and the mass percentage of NaCl is ≤0.7%; and / or, In the sodium alginate, the mass percentage of Na₂O is 9.5%~13.0%, and the mass percentage of P is ≤0.050%; and / or, In the graphite, the mass percentage of fixed carbon is ≥90.0%, and the mass percentage of S is ≤0.05%.

4. The welding electrode according to claim 3, characterized in that, The particle size requirements for the carbonates are: 100% by mass of -30 mesh, ≥97% by mass of -40 mesh, and ≤70% by mass of -170 mesh; and / or, The particle size requirements for the fluoride are: 100% by mass of -30 mesh, ≥97% by mass of -40 mesh, and ≤70% by mass of -170 mesh; and / or, The rutile particle size requirements are: -40 mesh ≤ 100% by mass, -160 mesh ≤ 30% by mass; and / or, The particle size requirements for the silica are: -30 mesh ≥ 100% by mass, -40 mesh ≥ 98% by mass, and -200 mesh ≤ 20% by mass; and / or, The particle size requirements for the electrolytic manganese are: -30 mesh ≥ 100% by mass, -40 mesh ≥ 98% by mass, and -170 mesh ≤ 50% by mass; and / or, The loose bulk density of the iron powder is 2.9 g / cm³. 3 ~3.1g / cm 3 The particle size requirements are: -30 mesh ≥ 100% mass percentage, -40 mesh ≥ 98% mass percentage, -170 mesh ≤ 20% mass percentage; and / or, The particle size requirements for the soda ash are: 100% by mass of -30 mesh, ≥98% by mass of -40 mesh; and / or, The sodium alginate has an ash content of 20.0%~30.0% and a particle size requirement of 100% by mass of -100 mesh; and / or, The weight loss rate of the graphite is ≤2.0%, and the particle size requirement is: -200 mesh mass percentage is 100%.

5. A method for preparing the Q500qENH uncoated bridge welding electrode according to any one of claims 1 to 4, characterized in that, The method includes: The raw materials of the herb peel are mixed to obtain the first mixture; The first mixture was wet-mixed with water glass in a potassium-sodium molar ratio of 1:1 to obtain the second mixture. The second mixture is coated onto the outside of a low-sulfur-phosphorus welding core and then baked to obtain a welding electrode.

6. The method according to claim 5, characterized in that, The water glass is added at a mass fraction of 21% to 23% of the mass of the first mixture, and the water glass has a Baumé density of 41Be to 42Be.

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