High-fracture-toughness electro-gas welding flux-cored wire for storage tank

Abstract

The invention provides a high-fracture-toughness electro-gas welding flux-cored wire for a storage tank, which comprises a flux core and a sheath, and the flux core accounts for 22-25% of the total mass of the flux-cored wire; the flux core comprises, by weight, 6-12 parts of titanium dioxide, 8-12 parts of quartz, 30-50 parts of fluoride, 14-24 parts of carbonate, 3-8 parts of magnesium oxide, 3-8 parts of calcium oxide, 70-90 parts of silicon-manganese alloy, 30-40 parts of electrolytic manganese, 6-10 parts of magnesium powder, 6-10 parts of aluminum-magnesium alloy, 10-20 parts of silicon iron, 10-15 parts of ferromolybdenum, 15-25 parts of titanium-boron alloy, 25-30 parts of nickel powder and 700 parts of iron powder. Wherein the ratio of fluoride to (titanium dioxide and quartz) is (1.5-2.5): 1. The welding wire has good tensile strength, low-temperature impact toughness and fracture toughness.

Description

Technical Field

[0001] The invention belongs to the field of welding wire production, and in particular relates to a flux-cored wire for electro-gas welding with high fracture toughness for storage tanks. Background Art

[0002] In the wave of the increasingly prosperous economy and accelerating industrialization process in our country, as an important storage and transportation equipment, large storage tanks have become increasingly prominent. In many fields such as petroleum, chemical industry, natural gas and food, they bear the heavy responsibility of storage and transportation, and become an important link to ensure the smooth flow of the supply chain in each link. The large storage tank industry shows a booming development trend. Fracture toughness is an important index reflecting the mechanical properties of materials, which affects the service life and performance of materials. Materials with high fracture toughness can maintain high strength and stability under stress, and have stronger service life and durability. The steel used in the storage tank industry has a large thickness and harsh service conditions. The electro-gas welding process is widely used. Inventing a flux-cored wire for electro-gas welding with high fracture toughness is of great significance for the safety and reliability of the storage tank industry in our country. Summary of the Invention

[0003] In view of this, the present invention aims to provide a flux-cored wire for electro-gas welding with high fracture toughness for storage tanks, which has good arc stability, less spatter, beautiful forming, easy slag removal and excellent fracture toughness, and fully meets the high demand standards of electro-gas welding.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] A flux-cored wire for electro-gas welding with high fracture toughness for storage tanks, comprising a flux core and an outer skin, wherein the flux core accounts for 22%-25% of the total mass of the welding wire; the flux core comprises the following components in parts by weight: 6-12 parts of titanium dioxide, 8-12 parts of quartz, 30-50 parts of fluoride, 14-24 parts of carbonate, 3-8 parts of magnesium oxide, 3-8 parts of calcium oxide, 70-90 parts of ferrosilicon manganese alloy, 30-40 parts of electrolytic manganese, 6-10 parts of magnesium powder, 6-10 parts of aluminum-magnesium alloy, 10-20 parts of ferrosilicon, 10-15 parts of ferromolybdenum, 15-25 parts of titanium-boron alloy, 25-30 parts of nickel powder, and 700 parts of iron powder; wherein, fluoride:(titanium dioxide + quartz)=(1.5-2.5):1.

[0006] Further, the fluoride is a mixture of sodium fluoride and calcium fluoride. By weight, the flux core contains 15-25 parts of sodium fluoride and 15-25 parts of calcium fluoride.

[0007] Further, the carbonate is a mixture of sodium carbonate and potassium carbonate.

[0008] Further, by weight, the flux core contains 8-12 parts of sodium carbonate and 6-12 parts of potassium carbonate.

[0009] Furthermore, the diameter of the welding wire is 1.6 mm.

[0010] Furthermore, the tensile strength of the deposited metal of the welding wire is ≥490 MPa, the yield strength is ≥390 MPa, the elongation is ≥20%, the impact toughness at -20°C is ≥60 J, and the fracture toughness index of the welded joint: the crack tip opening displacement CTOD at -20°C is ≥0.25 mm.

[0011] Among them, the fluoride is a mixture of sodium fluoride and calcium fluoride. The fluoride is the main slag-forming agent, which can play a role in thinning the slag and is beneficial to slag removal. Calcium fluoride is used in the traditional flux-cored wire formula. It is a good dehydrogenating agent, but when the content is relatively high, it is not conducive to arc stability, the spatter increases, and the welding processability is affected. The present invention preferably uses a mixture of sodium fluoride and calcium fluoride. Sodium fluoride is a good arc stabilizing agent. It can reduce the slag viscosity and improve the physical and chemical properties of the slag under the condition of ensuring the best dehydrogenation and arc stabilization effects, which is beneficial to slag removal. The fluoride increases the slag basicity, purifies the purity of the weld metal, and increases the CTOD value of the weld metal.

[0012] The carbonate is the main slag-forming agent, which can improve the slag viscosity. The decomposed CO2 plays a role in protecting the molten pool. The present invention preferably uses a mixture of sodium carbonate and potassium carbonate. Na2O is a low-ionization-degree oxide, which can provide electrons and jointly play a role in stabilizing the arc with K2O, improving the welding process performance.

[0013] Magnesium powder and electrolytic manganese: They are the main deoxidizers and desulfurizers, which can effectively reduce the impurity content of the deposited metal. The oxidation product MgO of magnesium powder can increase the slag basicity and improve the low-temperature impact toughness of the deposited metal.

[0014] Titanium-boron alloy: Ti can refine the weld metal structure, promote the formation of acicular ferrite in the weld metal, refine the grains, and improve the mechanical properties of the deposited metal. Titanium element can also form stable carbides to avoid the precipitation of Cr-rich carbides at the grain boundaries. Therefore, adding titanium element can also prevent intergranular corrosion.

[0015] Nickel powder and ferromolybdenum: Their combined action can inhibit the formation of proeutectoid ferrite, refine the grains, and improve the low-temperature impact toughness and CTOD value of the deposited metal.

[0016] Ferrosilicon and silicomanganese alloy: Silicon is an important deoxidizer and also an important alloying agent for the weld metal. An appropriate amount of silicon element can improve the impact toughness of the weld metal. Silicon and manganese have formed a mature toughening mechanism and can also play a combined deoxidation effect.

[0017] Iron powder: The present invention selects reduced iron powder. Adding iron powder to the flux-cored wire can improve the welding efficiency, and the small amount of oxygen provided plays an arc stabilizing role.

[0018] Compared with the prior art, the flux-cored wire for electro-gas vertical welding with high fracture toughness for storage tanks described in the present invention has the following advantages:

[0019] The flux-cored wire for electro-gas welding with high fracture toughness for storage tanks of the present invention has good tensile strength, low-temperature impact toughness and fracture toughness. It is used for electro-gas welding of the side plates of storage tanks, which can effectively improve the safety of the butt welds of storage tanks, extend the service life, and reduce the welding material cost and comprehensive maintenance cost. Detailed implementation manners

[0020] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in combination with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Embodiment 1

[0023] A flux-cored wire for electro-gas welding with high fracture toughness for storage tanks, the wire diameter is 1.6 mm, including a flux core and an outer skin. The flux core accounts for 24% of the total mass of the wire. The flux core includes the following components in parts by weight: 10 parts of titanium dioxide, 10 parts of quartz, 20 parts of sodium fluoride, 20 parts of calcium fluoride, 10 parts of sodium carbonate, 9 parts of potassium carbonate, 5 parts of magnesium oxide, 5 parts of calcium oxide, 70 parts of ferrosilicon manganese alloy, 40 parts of electrolytic manganese, 10 parts of magnesium powder, 6 parts of aluminum-magnesium alloy, 20 parts of ferrosilicon, 15 parts of ferromolybdenum, 15 parts of titanium-boron alloy, 25 parts of nickel powder, and 700 parts of iron powder.

[0024] Among them, (sodium fluoride + calcium fluoride):(titanium dioxide + quartz) = 2:1.

[0025] Embodiment 2

[0026] A flux-cored wire for electro-gas welding with high fracture toughness for storage tanks, the wire diameter is 1.6 mm, including a flux core and an outer skin. The flux core accounts for 22% of the total mass of the wire. The flux core includes the following components in parts by weight: 6 parts of titanium dioxide, 12 parts of quartz, 25 parts of sodium fluoride, 15 parts of calcium fluoride, 8 parts of sodium carbonate, 12 parts of potassium carbonate, 8 parts of magnesium oxide, 3 parts of calcium oxide, 80 parts of ferrosilicon manganese alloy, 35 parts of electrolytic manganese, 8 parts of magnesium powder, 8 parts of aluminum-magnesium alloy, 15 parts of ferrosilicon, 13 parts of ferromolybdenum, 25 parts of titanium-boron alloy, 30 parts of nickel powder, and 700 parts of iron powder.

[0027] Among them, (sodium fluoride + calcium fluoride):(titanium dioxide + quartz) = 2.22:1.

[0028] Embodiment 3

[0029] A flux-cored wire for gas-electric vertical welding with high fracture toughness for storage tanks, the wire diameter is 1.6 mm, including a flux core and an outer skin, and the flux core accounts for 23% of the total mass of the wire; the flux core includes the following components in parts by weight: 12 parts of titanium dioxide, 8 parts of quartz, 15 parts of sodium fluoride, 25 parts of calcium fluoride, 12 parts of sodium carbonate, 6 parts of potassium carbonate, 3 parts of magnesium oxide, 8 parts of calcium oxide, 90 parts of ferrosilicon manganese alloy, 30 parts of electrolytic manganese, 6 parts of magnesium powder, 10 parts of aluminum-magnesium alloy, 10 parts of ferrosilicon, 10 parts of ferromolybdenum, 20 parts of titanium-boron alloy, 27 parts of nickel powder, and 700 parts of iron powder.

[0030] Among them, (sodium fluoride + calcium fluoride):(titanium dioxide + quartz) = 2:1.

[0031] Table 1 Chemical composition of the deposited metal of the flux-cored wire in Examples 1-3 (%)

[0032] Test Items C S Mn Si P Ni Mo Ti Example 1 0.071 0.006 1.68 0.25 0.009 0.58 0.21 0.038 Example 2 0.068 0.005 1.71 0.26 0.008 0.65 0.17 0.045 Example 3 0.065 0.005 1.75 0.26 0.009 0.62 0.14 0.036

[0033] Table 2 Mechanical properties of the deposited metal of the flux-cored wire in Examples 1-3

[0034]

[0035]

[0036] It can be seen from Table 2 that the tensile strength of the deposited metal of the flux-cored wire of the present invention is ≥490 MPa, the yield strength is ≥390 MPa, the elongation is ≥20%, the impact toughness at -20°C is ≥60 J, and the fracture toughness index of the welded joint: the crack tip opening displacement CTOD at -20°C is ≥0.25 mm.

[0037] In Comparative Example 1, there are too many alloying elements

[0038] A flux-cored wire for gas-electric vertical welding with high fracture toughness for storage tanks, the wire diameter is 1.6 mm, including a flux core and an outer skin, and the flux core accounts for 24% of the total mass of the wire; the flux core includes the following components in parts by weight: 10 parts of titanium dioxide, 10 parts of quartz, 20 parts of sodium fluoride, 20 parts of calcium fluoride, 10 parts of sodium carbonate, 9 parts of potassium carbonate, 5 parts of magnesium oxide, 5 parts of calcium oxide, 100 parts of ferrosilicon manganese alloy, 50 parts of electrolytic manganese, 10 parts of magnesium powder, 6 parts of aluminum-magnesium alloy, 25 parts of ferrosilicon, 25 parts of ferromolybdenum, 15 parts of titanium-boron alloy, 25 parts of nickel powder, and 700 parts of iron powder.

[0039] Table 3 Chemical composition of the deposited metal of the flux-cored wire in Comparative Example 1 (%)

[0040] Test Items C S Mn Si P Ni Mo Ti Comparative Example 1 0.08 0.005 2.22 0.36 0.011 0.55 0.32 0.052

[0041] Table 4 Mechanical properties of the deposited metal of the flux-cored wire in Comparative Example 1

[0042]

[0043] Example 2: Insufficient slag former

[0044] A flux-cored wire for high fracture toughness electro-gas vertical welding of storage tanks, with a wire diameter of 1.6 mm, including a flux core and an outer skin. The flux core accounts for 22% of the total mass of the wire. The flux core includes the following components in parts by weight: 4 parts of titanium dioxide, 6 parts of quartz, 10 parts of sodium fluoride, 10 parts of calcium fluoride, 8 parts of sodium carbonate, 12 parts of potassium carbonate, 8 parts of magnesium oxide, 3 parts of calcium oxide, 80 parts of ferrosilicon manganese alloy, 35 parts of electrolytic manganese, 8 parts of magnesium powder, 8 parts of aluminum-magnesium alloy, 15 parts of ferrosilicon, 13 parts of ferromolybdenum, 25 parts of titanium-boron alloy, 30 parts of nickel powder, and 700 parts of iron powder.

[0045] Table 5 Chemical composition of the deposited metal of the flux-cored wire in Example 2 (%)

[0046] Test Items C S Mn Si P Ni Mo Ti Comparative Example 2 0.006 0.006 1.65 0.28 0.012 0.45 0.19 0.036

[0047] Table 6 Mechanical properties of the deposited metal of the flux-cored wire in Example 2

[0048]

[0049] Example 3: The ratio of fluoride to (titanium dioxide + quartz) does not meet the requirements

[0050] Scheme a: Fluoride:(titanium dioxide + quartz) = 1.25 (less than the specified ratio)

[0051] A flux-cored wire for high fracture toughness electro-gas vertical welding of storage tanks, with a wire diameter of 1.6 mm, including a flux core and an outer skin. The flux core accounts for 23% of the total mass of the wire. The flux core includes the following components in parts by weight: 12 parts of titanium dioxide, 12 parts of quartz, 15 parts of sodium fluoride, 15 parts of calcium fluoride, 12 parts of sodium carbonate, 6 parts of potassium carbonate, 3 parts of magnesium oxide, 8 parts of calcium oxide, 90 parts of ferrosilicon manganese alloy, 30 parts of electrolytic manganese, 6 parts of magnesium powder, 10 parts of aluminum-magnesium alloy, 10 parts of ferrosilicon, 10 parts of ferromolybdenum, 20 parts of titanium-boron alloy, 27 parts of nickel powder, and 700 parts of iron powder.

[0052] Scheme b: Fluoride:(titanium dioxide + quartz) = 2.86 (greater than the specified ratio)

[0053] A flux-cored wire for high fracture toughness electro-gas vertical welding of storage tanks, with a wire diameter of 1.6 mm, including a flux core and an outer skin. The flux core accounts for 23% of the total mass of the wire. The flux core includes the following components in parts by weight: 8 parts of titanium dioxide, 6 parts of quartz, 15 parts of sodium fluoride, 25 parts of calcium fluoride, 12 parts of sodium carbonate, 6 parts of potassium carbonate, 3 parts of magnesium oxide, 8 parts of calcium oxide, 90 parts of ferrosilicon manganese alloy, 30 parts of electrolytic manganese, 6 parts of magnesium powder, 10 parts of aluminum-magnesium alloy, 10 parts of ferrosilicon, 10 parts of ferromolybdenum, 20 parts of titanium-boron alloy, 27 parts of nickel powder, and 700 parts of iron powder.

[0054] Table 7 Chemical composition of the deposited metal of the flux-cored wire in Comparative Example 3 (%)

[0055] Test Items C S Mn Si P Ni Mo Ti Scheme a 0.067 0.007 1.68 0.26 0.011 0.48 0.18 0.038 Scheme b 0.065 0.006 1.66 0.25 0.012 0.46 0.17 0.036

[0056] Table 8 Mechanical properties of the deposited metal of the flux-cored wire in Comparative Example 3

[0057]

[0058] Result analysis:

[0059] Too many alloying elements were added in Comparative Example 1, resulting in too high tensile strength of the deposited metal, reduced elongation, and great influence on impact toughness and crack tip opening displacement.

[0060] In Comparative Example 2, due to insufficient addition of slag-forming agent, a large area of the weld surface was not covered with slag, resulting in poor weld formation and affecting the impact toughness and crack tip opening displacement values.

[0061] In Comparative Example 3, since the ratio of (sodium fluoride + calcium fluoride):(titanium dioxide + quartz) exceeded the requirement, when the oxide ratio was too high, the purity of the weld structure was poor, affecting the impact toughness and crack tip opening displacement values; when the fluoride ratio was too high, the melting point of the slag was high, there was too much slag in the molten pool, and the welding stability was poor, affecting the weld formation.

[0062] In summary, the process performance and mechanical property indexes of the flux-cored wire in Examples 1 to 3 are superior to those in the comparative examples.

[0063] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A flux-cored wire for gas-electric vertical welding with high fracture toughness for storage tanks, characterized in that: It includes a flux-cored wire and an outer skin, and the flux-cored wire accounts for 22%-25% of the total mass of the welding wire; the flux-cored wire comprises components in the following parts by weight: 6-12 parts of titanium dioxide, 8-12 parts of quartz, 30-50 parts of fluoride, 14-24 parts of carbonate, 3-8 parts of magnesium oxide, 3-8 parts of calcium oxide, 70-90 parts of ferrosilicon manganese alloy, 30-40 parts of electrolytic manganese, 6-10 parts of magnesium powder, 6-10 parts of aluminum-magnesium alloy, 10-20 parts of ferrosilicon, 10-15 parts of ferromolybdenum, 15-25 parts of titanium-boron alloy, 25-30 parts of nickel powder, and 700 parts of iron powder; wherein, fluoride:(titanium dioxide + quartz)=(1.5-2.5):

1.

2. The flux-cored wire for electro-gas welding with high fracture toughness for storage tanks according to claim 1, wherein: The fluoride is a mixture of sodium fluoride and calcium fluoride. By weight, the flux-cored wire contains 15-25 parts of sodium fluoride and 15-25 parts of calcium fluoride.

3. The flux cored wire for gas-electric vertical welding with high fracture toughness for storage tanks according to claim 1, characterized in that: The carbonate is a mixture of sodium carbonate and potassium carbonate.

4. The flux cored wire for gas-electric vertical welding with high fracture toughness for storage tanks according to claim 3, characterized in that: By weight, the flux-cored wire contains 8-12 parts of sodium carbonate and 6-12 parts of potassium carbonate.

5. The flux-cored wire for gas-electric vertical welding with high fracture toughness for storage tanks according to claim 1, wherein: The diameter of the welding wire is 1.6 mm.

6. The flux-cored wire for gas-electric vertical welding with high fracture toughness for storage tanks according to claim 1, characterized in that: The tensile strength of the deposited metal of the welding wire is ≥490 MPa, the yield strength is ≥390 MPa, the elongation is ≥20%, the impact toughness at -20°C is ≥60 J, and the fracture toughness index of the welded joint: the crack tip opening displacement CTOD at -20°C is ≥0.25 mm.

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