An electric welding rod for petrochemical low temperature storage tank

Abstract

The application discloses a kind of electric welding rod for petrochemical low temperature storage tank, it is made of welding core and coating, coating is applied to the outer wall of welding core, and the weight percentage of deposited metal chemical composition is as follows: C: 0.020-0.040%, Si: 0.15-0.25%, Mn: 0.50~0.80%, P: ≤0.008%, S: ≤0.008%, P+S ≤0.015%, Ni: 3.30~3.70%, Mo: 0.06-0.08%, B: 0.0012-0.0018%, Mo / B=30-60, Ti: ≤0.001%, the rest is Fe.The welding rod has high deposition efficiency, wide adaptability, can be AC or DC welding, the strength of deposited metal can meet the standard requirements after long-time heat treatment at 620℃×6-14h and the impact value at-101℃ can reach more than 120J, and can meet the welding requirements of large scale, large line energy and high efficiency.

Description

Technical Field

[0001] This invention belongs to the field of welding materials, and specifically relates to an electric welding electrode for petrochemical cryogenic storage tanks. Background Technology

[0002] Since the late 1980s, my country has focused on the localization of cryogenic equipment in large-scale ethylene, synthetic ammonia, and city gas plants, and has established specific research and development projects for cryogenic steel and its application technologies, with the application of 3.5% Ni steel being the primary priority. 3.5% Ni steel is a type of Ni-containing cryogenic steel, with a minimum operating temperature generally reaching -101℃ (and -120℃ in its tempered state), and is widely used in the manufacture of petrochemical cryogenic equipment operating at temperatures from -80 to -101℃.

[0003] 3.5% Ni steel is mainly used in the manufacture of containers for petroleum and air separation oxygen production equipment, as well as synthetic ammonia. With the development of the petrochemical industry, petrochemical storage tanks are becoming increasingly larger, and the thickness of steel plates is also constantly increasing, leading to a growing demand for this steel in my country. Wuyang Iron & Steel Co., Ltd. began developing 3.5% Ni steel plates in 2007, achieving domestic substitution for imports in major national projects. Developing welding materials with performance indicators approaching those of similar foreign products, capable of handling large storage tanks, thick plates, high heat input, high efficiency, and long-term heat treatment, is essential. This has significant practical implications and substantial economic benefits for achieving the domestic production of 3.5% Ni steel welding materials, promoting the development of the national welding materials industry, and advancing the wider application of 3.5% Ni steel in my country's petrochemical industry.

[0004] Currently, welding materials still largely rely on imports. Existing welding electrodes designed for 3.5% Ni steel often have the following drawbacks: excessive welding current or heat input significantly reduces the weld metal's low-temperature toughness at -101℃; furthermore, to ensure impact toughness at -101℃, commercially available welding materials are generally designed with equal or low strength matching principles. With the increasing size of storage tanks, the thickness of steel plates also increases, requiring a corresponding increase in the heat treatment time of welding materials. Increased heat treatment time leads to a decrease in weld metal strength, making it difficult to meet standard requirements under prolonged heat treatment conditions. However, simply increasing the electrode strength will significantly degrade its impact toughness at -101℃. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a welding electrode for petrochemical cryogenic storage tanks. The weld metal, after long-term heat treatment at 620℃ for 6-14 hours, meets standard strength requirements, and its impact value at -101℃ reaches over 120J. This solves the common defects in existing welding electrodes designed for 3.5% Ni steel, such as decreased low-temperature toughness and reduced metal strength. The electrode also features a stable and gentle arc, high deposition efficiency, good all-position weldability, uniform slag coverage, easy slag removal, and aesthetically pleasing weld formation. Furthermore, the electrode has wide adaptability, can be used for both AC and DC welding, and can meet the demands of large-scale, high-energy, and high-efficiency welding.

[0006] The technical solution of this invention is an electric welding electrode for petrochemical cryogenic storage tanks, consisting of a welding core and a flux coating, with the flux coating applied to the outer wall of the welding core. Based on the total weight of the welding core, the composition of the welding core is as follows by weight percentage: C≤0.020%, Si≤0.10%, Mn: 0.35-0.60%, P≤0.005%, S≤0.008%, P+S≤0.012%, Ni: 3.0-3.75%, Fe: balance.

[0007] Based on the total weight of the drug coating, the composition of the drug coating by weight percentage is as follows: magnesite: 5-12%, calcite: 24-32%, barium carbonate: 2-4%, fluorite: 12-18%, barium fluoride: 3.0-5.0%, lithium fluoride: 1.0-3.0%, cerium fluoride: 0.4-1.2%, silica fume: 3-10%, zircon sand: 0.6-2.5%, potassium cryolite: 1.0-3.0%, potassium glass powder: 0. 5-2.0%, Low-nitrogen nickel powder (N≤0.005%): 2.6-3.4%, Low-nitrogen molybdenum powder (N≤0.005%): 0.15-0.18%, Manganese silicon alloy: 3-6%, Boron iron (B content 18-20%): 0.1-0.3%, Magnesium powder: 0.5-1.2%, Calcium alginate: 0.8-1.2%, Potassium alginate: 0.4-0.6%, Low-titanium atomized iron powder (Ti≤0.005%): Balance.

[0008] Add 15-30% of potassium-sodium mixed water glass with a modulus of 3.30 and a concentration of 35±1Be by weight of the coating. After mixing with the coating, coat it evenly onto the welding core. Then dry it at low temperature (80-120℃) for 3 hours and at high temperature (350-420℃) for 1 hour to make the welding electrode for petrochemical low-temperature storage tanks.

[0009] The chemical composition of the weld metal of the welding electrode for petrochemical cryogenic storage tank, by weight percentage, is as follows: C: 0.020-0.040%, Si: 0.15-0.25%, Mn: 0.50-0.80%, P: ≤0.008%, S: ≤0.008%, P+S≤0.015%, Ni: 3.30-3.70%, Mo: 0.06-0.08%, B: 0.0012-0.0018%, Mo / B = 30-60, Ti: ≤0.001%, with the remainder being Fe.

[0010] Preferably, the composition of the welding core is as follows: 0.010≤C≤0.020%; Si≤0.10%; Mn: 0.35~0.60%; P: ≤0.005%; S: ≤0.005%; P+S≤0.010%; Ni: 3.20-3.75%; Fe: balance.

[0011] Preferably, the composition of the coating is as follows: magnesite: 6-10%; calcite: 26-30%; barium carbonate: 2.5-4.0%; fluorite: 14-16%; barium fluoride: 3.5-4.8%; lithium fluoride: 1.6-2.4%; cerium fluoride: 0.6-1.0%; silica fume: 6-9%; zircon sand: 0.6-1.8%; potassium cryolite: 1.6-3.0%; potassium glass powder: 1.0-2.0%; low nitrogen... Nickel powder (N≤0.005%): 2.8-3.2%; Low-nitrogen molybdenum powder (N≤0.005%): 0.15-0.18%; Manganese silicon alloy: 4.2-5.8%; Boron iron (B: 18-20%): 0.15-0.30%; Magnesium powder: 0.75-1.20%; Calcium alginate: 0.8-1.2%; Potassium alginate: 0.4-0.6%; Low-titanium atomized iron powder (Ti≤0.005%): Balance.

[0012] Preferably, the silica powder in the coating component is micron-sized, with an extremely fine particle size, passing through 500 mesh; the potassium glass powder has a particle size of 250-300 mesh; and the calcium alginate and potassium alginate have a particle size of 150-200 mesh.

[0013] Preferably, the chemical composition of the weld metal of the welding electrode for petrochemical cryogenic storage tank, by weight percentage, is controlled as follows: C: 0.024-0.036%, Si: 0.15-0.22%, Mn: 0.58-0.72%, P: ≤0.006%, S: ≤0.006%, P+S≤0.012%, Ni: 3.45-3.65%, Mo: 0.06-0.08%, B: 0.0012-0.0018%, Mo / B = 36-54, Ti: ≤0.001%, with the remainder being Fe.

[0014] Preferably, as a preferred embodiment of the welding electrode for petrochemical cryogenic storage tanks of the present invention, its core composition is as follows: C: 0.013%; Si: 0.03%; Mn: 0.42%; P: 0.003%; S: 0.005%; P+S: 0.008%; Ni: 3.27%; Fe: balance; the coating composition is as follows: magnesite: 7.4%; calcite: 26.0%; barium carbonate: 2.6%; fluorite: 15.0%; barium fluoride: 4.2%; lithium fluoride: 2.4%. Cerium fluoride: 1.0%; Silica powder: 6.0%; Zircon sand: 1.7%; Potassium cryolite: 1.6%; Potassium glass powder: 1.1%; Low-nitrogen nickel powder (N≤0.005%): 2.9%; Low-nitrogen molybdenum powder (N≤0.005%): 0.15%; Manganese silicon alloy: 4.25%; Boron iron (B: 18-20%): 0.15%; Magnesium powder: 0.85%; Calcium alginate: 0.90%; Potassium alginate: 0.40%; Low-titanium atomized iron powder (Ti≤0.005%): Balance.

[0015] Preferably, as another preferred embodiment of the welding electrode for petrochemical cryogenic storage tanks of the present invention, its core composition is as follows: C: 0.017%; Si: 0.04%; Mn: 0.35%; P: 0.005%; S: 0.005%; P+S: 0.010%; Ni: 3.44%; Fe: balance; the coating composition is as follows: magnesite: 10.0%; calcite: 30.0%; barium carbonate: 2.8%; fluorite: 14.0%; barium fluoride: 4.0%; lithium fluoride: 1.6%. %; Cerium fluoride: 0.8%; Silica powder: 6.7%; Zircon sand: 1.0%; Potassium cryolite: 2.4%; Potassium glass powder: 1.6%; Low-nitrogen nickel powder (N≤0.005%): 2.8%; Low-nitrogen molybdenum powder (N≤0.005%): 0.18%; Manganese silicon alloy: 5.00%; Boron iron (B: 18-20%): 0.25%; Magnesium powder: 1.00%; Calcium alginate: 1.10%; Potassium alginate: 0.55%; Low-titanium atomized iron powder (Ti≤0.005%): Balance.

[0016] Preferably, as another preferred embodiment of the welding electrode for petrochemical cryogenic storage tanks of the present invention, its core composition is as follows: C: 0.011%; Si: 0.04%; Mn: 0.47%; P: 0.004%; S: 0.003%; P+S: 0.007%; Ni: 3.75%; Fe: balance; the coating composition is as follows: magnesite: 9.7%; calcite: 28.0%; barium carbonate: 4.0%; fluorite: 16.0%; barium fluoride: 3.6%; lithium fluoride: 1.8%. %; Cerium fluoride: 0.7%; Silica powder: 8.0%; Zircon sand: 0.6%; Potassium cryolite: 3.0%; Potassium glass powder: 2.0%; Low-nitrogen nickel powder (N≤0.005%): 3.1%; Low-nitrogen molybdenum powder (N≤0.005%): 0.17%; Manganese silicon alloy: 5.40%; Boron iron (B: 18-20%): 0.30%; Magnesium powder: 1.20%; Calcium alginate: 1.20%; Potassium alginate: 0.60%; Low-titanium atomized iron powder (Ti≤0.005%): Balance.

[0017] The beneficial effects of this invention based on its technical solution are:

[0018] This invention relates to an ultra-low carbon low alloy welding core, with the main alloying elements transitioning from the welding core. The ultra-low P and S composition design is a prerequisite for ensuring that the weld metal has excellent crack resistance and high toughness.

[0019] The formation of carbides during welding significantly reduces the impact toughness of the weld, especially at low temperatures of -101°C. To ensure good impact toughness at -101°C, this invention employs a high-basicity, high-potassium, low-hydrogen slag system. As is well known, higher basicity results in a higher carbon increase in the weld relative to the core material. To ensure a low carbon content in the weld, an ultra-low-carbon, low-alloy core material is designed. Through precise flux formulation and optimized alloy element composition and proportions, the resulting weld metal exhibits superior chemical stability and better impact stability at -101°C under prolonged heat treatment and high heat input welding conditions.

[0020] This invention employs a high-potassium, high-alkalinity, low-hydrogen slag system, exhibiting excellent arc stability and allowing for both AC and DC welding. The addition of varying proportions of multi-component fluorides enhances hydrogen removal capabilities; the high proportion of carbonates with different decomposition temperatures increases the CO2 partial pressure and reduces the hydrogen partial pressure in the arc atmosphere throughout the welding process; and the absence of silicate minerals with high water of crystallization content results in low levels of diffusing hydrogen. The precise ratio of multi-component carbonates and fluorides ensures uniform flux melting, good arc stiffness, and excellent all-position weldability.

[0021] This invention incorporates micron-sized silicon powder and potassium glass powder with a particle size of 200-300 mesh, which makes the electrode coating smoother, improves its density, and enhances its moisture resistance.

[0022] This invention employs an alloy system comprising low C, medium Mn, low Si, 3.5% Ni, and Mo and B. High Ni, low C, and low Si provide the fundamental guarantee for impact toughness at -101℃. Microalloying with small amounts of Mo and trace amounts of B is crucial for maintaining the weld's strength during long-term heat treatment. The absence of Ti is the core factor ensuring stable impact toughness at -101℃ under long-term heat treatment and high heat input welding conditions. Small amounts of Mo and trace amounts of B refine the grain structure, strengthening the weld while improving its impact toughness. Maintaining the Mo / B ratio within the range of 30-60 is preferable, with 36-54 being optimal.

[0023] In this invention, the main functions of the electrode coating are to stabilize the arc, generate gas, form slag, deoxidize, and transfer a small amount of alloy to the weld.

[0024] The specific roles of the main components and alloys of the coating in the welding electrode of this invention are analyzed as follows:

[0025] The main functions of carbonates in welding electrodes are slag formation and gas generation, as well as desulfurization, which improves the crack resistance of the weld metal. The alkaline oxides such as CaO and MgO produced during decomposition increase the basicity of the slag and also regulate its melting point, viscosity, and surface tension. This invention employs a multi-component carbonate composition; a high proportion of carbonates with different decomposition temperatures increases the partial pressure of CO2 in the arc atmosphere throughout the welding process, reduces the partial pressure of hydrogen, and lowers the level of diffusing hydrogen in the welding material. The precise ratio of multi-component carbonates and fluorides results in uniform coating melting, good arc stiffness, and excellent all-position weldability. The carbonate content in this invention is controlled at 31-48%.

[0026] This invention employs a multi-component fluoride combination, consisting of fluorite (CaF2), barium fluoride, lithium fluoride, and cerium fluoride. This combination can adjust the melting point of the slag and reduce the surface tension of the liquid metal, playing a crucial role in reducing the diffusible hydrogen content in the weld and improving weld formation and slag removal. Extensive orthogonal experimental practice has demonstrated that the combination of fluorite, barium fluoride, and lithium fluoride results in exceptionally strong hydrogen removal capabilities in the coating. Furthermore, cerium fluoride, in addition to transitioning rare earth elements into the weld, also plays a role in hydrogen removal, deoxidation, purification, and impurity removal. The rare earth elements transitioning into the weld also play a key role in refining the weld metal microstructure and improving its strength and toughness. However, because rare earth elements are very expensive, adding too much would significantly increase manufacturing costs. Therefore, the rare earth fluoride content in the welding electrode of this invention is controlled at 0.4%–1.2%.

[0027] Silicon oxides and aluminum oxides obtained from silica powder, cryolite, potassium glass powder, and water glass can adjust the viscosity of molten weld slag, resulting in good slag coverage and improving weld appearance and shape. However, if the proportion of silicon oxides is too high, it will lead to excessive oxygen content in the weld, thereby reducing the mechanical properties of the weld, especially low-temperature impact toughness. It will also make slag removal difficult. Therefore, the proportion of silicon oxides and aluminum oxides in welding flux should be controlled at a low level.

[0028] This invention employs a Ti-free formulation design. As is well known, Ti is widely used in low-temperature steel welding materials, capable of deoxidation and grain refinement. Combined with boron in a suitable ratio, it can significantly improve weld microstructure and enhance low-temperature impact toughness. However, in 3.5% Ni steel welding materials, the Ti / B ratio is more difficult to control and its impact value is extremely unstable, especially after prolonged heat treatment. Therefore, most commercially available 3.5% Ni steel welding materials contain Ti but no B. To meet the strength and impact toughness requirements of the welding material after prolonged heat treatment, this invention adopts a Ti-free, low-C, medium-Mn, low-Si, 3.5% Ni, Mo-containing, and trace B alloy system. This invention uses titanium-free atomized iron powder and does not add titanium dioxide, rutile, or titanium alloys.

[0029] The main functions of ferroalloys and other metal powders are deoxidation and transition alloying, ensuring the alloy element composition in the weld, ensuring the weld strength, and achieving the best strength and toughness matching through reasonable element design. In particular, this invention specifically controls the ratio of low nitrogen molybdenum powder and ferroboron to control the Mo / B ratio of the deposited metal at 30-60 (preferably 36-54) to achieve the ideal comprehensive improvement effect of grain refinement, toughness enhancement and crack resistance.

[0030] The binder uses potassium sodium water glass combined with alginate with a particle size controlled at 100-200 mesh and micron-sized silica powder. The main functions of the binder are to plasticize, increase adhesion, improve the coating properties and appearance of the welding rod, as well as slag formation and arc stabilization.

[0031] The above explains the limitations on the coating composition of the welding electrode for petrochemical cryogenic storage tanks of this invention. The remaining portion consists of iron and unavoidable impurities.

[0032] The welding electrode of this invention is well-matched with the properties of 3.5% Ni steel plates, exhibiting high deposition efficiency, wide adaptability, and the ability to perform both AC and DC welding. After long-term heat treatment at 620℃ for 6-14 hours, the deposited metal meets standard strength requirements, and its impact value at -101℃ reaches over 120J. It also meets the demands of large-scale, high-heat-intensity, and high-efficiency welding. In addition to high strength and high toughness, the deposited metal, when vertically butt-welded with 3.5% Ni steel base material, exhibits a tensile strength ≥520MPa and an impact strength ≥70J at -101℃ after heat treatment at 620±20℃ for 6-14 hours. Detailed Implementation

[0033] To better understand the present invention, the technical solution of the present invention will be further described below with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0034] A welding electrode for petrochemical cryogenic storage tanks is a high-quality ultra-low carbon low alloy welding core with a flux coating on the outer wall of the core. The specific chemical composition (wt%) of the welding core is as follows: C≤0.020%, Si≤0.10%, Mn: 0.35-0.60%, P≤0.005%, S≤0.008%, P+S≤0.012%, Ni: 3.0-3.75%, Fe: balance.

[0035] Based on the total weight of the drug coating, the composition of the drug coating by weight percentage is as follows: magnesite: 5-12%, calcite: 24-32%, barium carbonate: 2-4%, fluorite: 12-18%, barium fluoride: 3.0-5.0%, lithium fluoride: 1.0-3.0%, cerium fluoride: 0.4-1.2%, silica fume: 3-10%, zircon sand: 0.6-2.5%, potassium cryolite: 1.0-3.0%, potassium glass powder: 0. 5-2.0%, Low-nitrogen nickel powder (N≤0.005%): 2.6-3.4%, Low-nitrogen molybdenum powder (N≤0.005%): 0.15-0.18%, Manganese silicon alloy: 3-6%, Boron iron (B: 18-20%): 0.1-0.3%, Magnesium powder: 0.5-1.2%, Calcium alginate: 0.8-1.2%, Potassium alginate: 0.4-0.6%, Low-titanium atomized iron powder (Ti≤0.005%): Balance.

[0036] Add 15-30% of potassium-sodium mixed water glass with a modulus of 3.30 and a concentration of 35±1Be to the total weight of the coating. Apply the coating flux evenly to the core using a hydraulic coating machine. Dry the core at low temperature (80-120℃) for 3 hours and at high temperature (350-420℃) for 1 hour to produce the welding rod.

[0037] The welding core of the present invention is a high-quality ultra-low carbon low alloy welding core. The specific contents in the embodiments are shown in Table 1 (wherein Examples 1, 3, and 4 are preferred embodiments [with better low-temperature impact toughness], the same below).

[0038] Table 1: Examples of solder core composition (weight percentage %)

[0039]

[0040] The coating uses a high-potassium, high-alkalinity, low-hydrogen slag system. The coating accounts for 0.50 to 0.62% of the total weight of the electrode. The core wire diameter is 3.2 mm, 4.0 mm, and 5.0 mm. The coating composition is shown in Table 2.

[0041] Table 2: Components of the drug coating in each example (weight percentage %)

[0042]

[0043] Table 2 (continued): Components of the drug coating in each example (weight percentage %)

[0044]

[0045] Table 3: Chemical composition of deposited metal in each embodiment (weight percentage %)

[0046]

[0047] The test results of the mechanical properties of the deposited metal for each embodiment are shown in Tables 4-1 and 4-2:

[0048] Table 4-1: Test Results of Deposited Metal Performance in Each Example (DC)

[0049]

[0050] Note: The above test data are as follows: welding material specification Φ4.0mm, heat treatment conditions 620±20℃×6h, heat input 10-15KJ / cm;

[0051] Table 4-2: Test Results of Deposited Metal Performance in Various Examples (Discussion)

[0052]

[0053] Note: The above test data are as follows: welding material specification Φ4.0mm, heat treatment conditions 620±20℃×6h, heat input 10-15KJ / cm;

[0054] Taking Example 4 as an example, experiments were conducted on it with different heat treatment times and different heat inputs. The results are shown in Tables 5 to 9.

[0055] Table 5 Properties of deposited metal under different heat treatment times

[0056]

[0057] Table 6: Properties of deposited metal under different heat inputs

[0058]

[0059] Table 7: Properties of deposited metal under different heat inputs

[0060]

[0061] Table 8: Performance of vertical welded joints under different heat inputs

[0062]

[0063] Table 9: Performance of vertical welded joints under different heat inputs

[0064]

[0065] As can be seen from the experimental results in Tables 5 to 9 above, the welding electrode of the present invention exhibits excellent weld metal performance and low diffusible hydrogen content. It also demonstrates excellent low-temperature impact toughness at -101℃ after heat treatment at 620℃ for 6–14 hours under different heat input conditions. When vertically welded to a 3.5% Ni steel base material, within a heat input range of 35 KJ / cm, after heat treatment at 620℃ for 6–14 hours, the tensile strength is ≥490 MPa (meeting relevant standard requirements), and the impact strength at -101℃ is ≥70 J. Furthermore, no cracks are observed during face bending, back bending, and transverse side bending, demonstrating excellent crack resistance.

[0066] This invention relates to welding electrodes suitable for welding petrochemical cryogenic storage tanks made of 3.5% Ni steel. The electrodes are highly adaptable, suitable for both AC and DC welding, and can withstand prolonged heat treatment (620±20℃×6~14h). They can handle high heat inputs (up to 35KJ / cm). The deposited metal exhibits high impact toughness at -101℃ (≥120J) under heat treatment conditions of 620±20℃×6~14h. This invention overcomes the common defects in existing welding electrodes designed for 3.5% Ni steel, such as decreased low-temperature toughness and reduced metal strength. The electrodes of this invention possess excellent all-position welding process performance and high deposition efficiency, meeting the welding requirements for thick plates, high heat inputs, and high efficiency resulting from the increasing size of storage tanks.

[0067] The embodiments described above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A welding electrode for petrochemical cryogenic storage tanks, comprising a core and a flux coating, wherein the flux coating is applied to the outer wall of the core, characterized in that, Based on the total weight of the welding core, the composition of the welding core is as follows according to weight percentage: C≤0.020%, Si≤0.10%, Mn: 0.35-0.60%, P≤0.005%, S≤0.008%, P+S≤0.012%, Ni: 3.0-3.75%, Fe: balance; Based on the total weight of the coating, the composition of the coating by weight percentage is as follows: magnesite: 5-12%, calcite: 24-32%, barium carbonate: 2-4%, fluorite: 12-18%, barium fluoride: 3.0-5.0%, lithium fluoride: 1.0-3.0%, cerium fluoride: 0.4-1.2%, silica fume: 3-10%, zircon: 0.6-2.5%, potassium cryolite: 1.0-3.0%, potassium glass powder: 0.5-2.0%, low-nitrogen nickel powder, wherein N≤0.005%: 2.6-3.4%, low-nitrogen molybdenum powder, wherein N≤0.005%: 0.15-0.18%, manganese silicon alloy: 3-6%, ferroboron, wherein B content: 18-20%. 0.1-0.3%, magnesium powder: 0.5-1.2%, calcium alginate: 0.8-1.2%, potassium alginate: 0.4-0.6%, low-titanium atomized iron powder, of which Ti≤0.005%: balance; Add 15-30% of potassium-sodium mixed water glass with a modulus of 3.30 and a concentration of 35±1Be to the total weight of the coating. After mixing with the coating, coat it evenly onto the welding core. Then dry it at low temperature (80~120℃) for 3 hours and at high temperature (350~420℃) for 1 hour to make the welding electrode for petrochemical low temperature storage tanks. The chemical composition of the weld metal of the welding electrode used in the petrochemical cryogenic storage tank is as follows (weight percentage): C: 0.020-0.040%, Si: 0.15-0.25%, Mn: 0.50-0.80%, P: ≤0.008%, S: ≤0.008%, P+S≤0.015%, Ni: 3.30-3.70%, Mo: 0.06-0.08%, B: 0.0012-0.0018%, Mo / B=30-60, Ti: ≤0.001%, with the remainder being Fe.

2. The welding electrode for petrochemical cryogenic storage tanks according to claim 1, characterized in that, The potassium glass powder in the coating component has a particle size of 200-300 mesh, and the calcium alginate and potassium alginate have a particle size of 100-200 mesh.

Images