Flux-cored material and flux-cored wire for welding 9% Ni steel and preparation method of flux-cored material and flux-cored wire

Abstract

The invention provides a flux-cored material for 9% Ni steel welding, a flux-cored wire and a preparation method of the flux-cored wire, and relates to the technical field of welding materials. The flux core material is prepared from the following raw materials in parts by weight: 18 to 28 parts of rutile, 1 to 3 parts of ferrotitanium, 5 to 10 parts of potassium albite, 1 to 3 parts of zirconium dioxide, 3.5 to 6.5 parts of quartz, 3.5 to 6.5 parts of manganese monoxide, 1 to 3 parts of magnesia, 1.5 to 2.5 parts of ferro-aluminum, 0.2 to 0.5 part of fluoride, 15 to 20 parts of chromium metal, 25 to 30 parts of nickel powder, 6 to 9 parts of molybdenum powder and 1.5 to 2.5 parts of ferrotungsten. The flux-cored wire made of the flux-cored material is suitable for all-position welding of 9% Ni steel welding, the welding arc is stable, splashing is small, weld joint forming is attractive, deslagging is easy, the mechanical property is excellent, and meanwhile the good air hole resistance is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of welding materials, and in particular to a flux-cored material and flux-cored welding wire for 9% Ni steel welding and a preparation method thereof. Background Art

[0002] Although my country's LNG (liquefied natural gas) industry started late, it has developed rapidly. 9% Ni steel is generally used for LNG storage and transportation. 9% Ni steel plates have been fully domestically produced by Nanjing Iron and Steel, Anshan Iron and Steel, etc. When welding 9% Ni steel, there are poor molten pool fluidity and shallow melting depth. Low melting point impurities are segregated and distributed on the grain boundaries during weld crystallization, which are prone to problems such as pores, incomplete penetration, hot cracks and poor impact toughness, which seriously restrict the widespread application of 9% Ni steel in the field of LNG storage and transportation. Flux-cored arc welding (FCAW) is highly favored in industrial production due to its advantages such as high deposition efficiency, suitability for a variety of welding positions and easy realization of automated welding. Although some domestic welding material manufacturers have conducted research, the flux-cored wire used for 9% Ni steel still has a large gap in all-position weldability and anti-pore ability, and has not been applied in batches. Summary of the invention

[0003] In view of the above problems existing in the prior art, the present invention provides a flux-cored material and flux-cored welding wire for 9% Ni steel welding and a preparation method thereof, so as to improve the problems of poor all-position processability and poor anti-porosity ability of the flux-cored welding wire for 9% Ni steel welding in the prior art.

[0004] To achieve the above-mentioned object and other related objects, the first aspect of the present invention provides a flux core material for 9% Ni steel welding, wherein the flux core material comprises the following raw materials in parts by weight: 18 to 28 parts of rutile, 1 to 3 parts of ferrotitanium, 5 to 10 parts of potassium-sodium feldspar, 1 to 3 parts of zirconium dioxide, 3.5 to 6.5 parts of quartz, 3.5 to 6.5 parts of manganese monoxide, 1 to 3 parts of magnesia, 1.5 to 2.5 parts of ferroaluminum, 0.2 to 0.5 parts of fluoride, 15 to 20 parts of metallic chromium, 25 to 30 parts of nickel powder, 6 to 9 parts of molybdenum powder, and 1.5 to 2.5 parts of ferrotungsten.

[0005] In one embodiment of the present invention, the fluoride includes any one or more of rare earth fluoride, fluorosilicate, sodium fluoride and potassium fluoride.

[0006] In one embodiment of the present invention, the rutile, the potassium-sodium feldspar and the quartz are respectively sieved through an 80-mesh sieve.

[0007] In one embodiment of the present invention, the metallic chromium, the nickel powder, the molybdenum powder and the tungsten iron are respectively sieved through a 120-mesh sieve.

[0008] In one embodiment of the present invention, the S content in all raw materials of the drug core material is ≤0.02%, and the P content is ≤0.02%.

[0009] The second aspect of the present invention provides a flux-cored welding wire for 9% Ni steel welding, the flux-cored welding wire comprises an outer skin and a flux-cored material coated in the outer skin, the flux-cored material comprises the following raw materials in parts by weight: 18 to 28 parts of rutile, 1 to 3 parts of ferrotitanium, 5 to 10 parts of potassium-sodium feldspar, 1 to 3 parts of zirconium dioxide, 3.5 to 6.5 parts of quartz, 3.5 to 6.5 parts of manganese monoxide, 1 to 3 parts of magnesia, 1.5 to 2.5 parts of ferroaluminum, 0.2 to 0.5 parts of fluoride, 15 to 20 parts of metallic chromium, 25 to 30 parts of nickel powder, 6 to 9 parts of molybdenum powder, 1.5-2.5 parts of tungsten iron; the outer skin is a nickel-based alloy, which, based on the total mass of the nickel-based alloy, includes the following components and the mass percentage of each component: C≤0.02%, Mn≤1.0%, Fe:4.0-7.0%, Si≤0.08%, S≤0.04%, P≤0.02%, Cu≤0.50%, Co≤0.25%, Cr:14.5-16.5%, Mo:15.0-17.0%, W:3.0-4.0%, and the balance is Ni and unavoidable impurities.

[0010] In one embodiment of the present invention, the filling factor of the drug core material is 20% to 22%.

[0011] In one embodiment of the present invention, the diameter of the flux-cored welding wire is 1.0-1.6 mm.

[0012] The third aspect of the present invention provides a method for preparing a flux-cored welding wire for welding 9% Ni steel, comprising the following steps:

[0013] After drying the components of the drug core material, add them into a powder mixer and stir and mix them evenly to obtain a drug core material mixture;

[0014] Roll the outer skin into a U-shaped groove;

[0015] Filling the drug core material mixture into the U-shaped groove;

[0016] The U-shaped groove containing the core material mixture is closed, rolled into an O-shaped shape, welded, and drawn to a set diameter.

[0017] In one embodiment of the present invention, the drying temperature of rutile, feldspar and zirconium dioxide in the core material is 900-950°C, and the drying time is 6-8h, and the drying temperature of the remaining components is 150-200°C, and the drying time is 2-3h.

[0018] The flux-cored welding wire for 9% Ni steel welding provided by the present invention, by adding manganese monoxide to the flux-cored material, can further reduce the oxygen content of the weld and reduce the porosity sensitivity on the basis of the combined deoxidation of titanium iron and aluminum iron; the steel strip is a nickel-based alloy steel strip with C ≤ 0.02%, which further reduces the generation of CO gas. Since the amount of CO generated during the welding process is reduced, the proportion of slag-forming agent in the flux-cored material can be appropriately increased to adjust the slag viscosity. The slag-forming agent of the present application selects TiO2-SiO2-ZrO2-Al2O3-MgO for combined slag-forming, which achieves excellent all-position welding operating performance, especially the molten pool is not easy to fall during vertical welding and overhead welding, and the weld formation is more beautiful and has better mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0020] Figure 1 The figure is a flow chart of the preparation of a flux-cored welding wire for welding 9% Ni steel according to an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following is an explanation of the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the features in the following embodiments and the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or according to the conditions recommended by the manufacturers.

[0022] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are familiar to those skilled in the art and the description of the present invention, and any method, device and material of the prior art similar or equivalent to the method, device and material in the embodiments of the present invention can also be used to implement the present invention.

[0023] The temperature at which the nickel-based alloy deposited metal begins to solidify is 1300-1400°C. The solidification speed of the nickel-based alloy deposited metal is relatively fast. After the CO gas is generated during welding, it has a short escape time and is easily retained in the weld, resulting in pore defects. In order to reduce pore defects, a common solution is to reduce the slag-forming agent in the flux-cored material to improve the permeability of the welding slag, but this method will increase the fluidity of the molten pool and deteriorate the controllability of all-position welding. Therefore, the present invention provides a flux-cored material and flux-cored welding wire for 9% Ni steel welding and a preparation method thereof to improve the problems of poor all-position processability and poor anti-pore ability of the flux-cored welding wire in the prior art.

[0024] The flux-cored welding wire provided in the present application includes the following raw materials in parts by weight: 18 to 28 parts of rutile, 1 to 3 parts of ferrotitanium, 5 to 10 parts of potassium-sodium feldspar, 1 to 3 parts of zirconium dioxide, 3.5 to 6.5 parts of quartz, 3.5 to 6.5 parts of manganese monoxide, 1 to 3 parts of magnesia, 1.5 to 2.5 parts of ferroaluminum, 0.2 to 0.5 parts of fluoride, 15 to 20 parts of metallic chromium, 25 to 30 parts of nickel powder, 6 to 9 parts of molybdenum powder, and 1.5 to 2.5 parts of ferrotungsten.

[0025] In one embodiment, the fluoride includes any one or more of rare earth fluoride, fluorosilicate, sodium fluoride and potassium fluoride. For example, rare earth fluoride, fluorosilicate, sodium fluoride or potassium fluoride, or any combination of the above fluorides, for example, a combination of rare earth fluoride and fluorosilicate, a combination of sodium fluoride and potassium fluoride, which are not listed here one by one.

[0026] In one embodiment, rutile, potassium-sodium feldspar and quartz are respectively sieved through 80 meshes, and metallic chromium, nickel powder, molybdenum powder and tungsten iron are respectively sieved through 120 meshes.

[0027] In one embodiment, the S content in all raw materials of the core material is ≤0.02%, and the P content is ≤0.02%.

[0028] The flux-cored welding wire for 9% Ni steel welding provided in the present application comprises an outer skin and a flux-cored material coated in the outer skin, wherein the flux-cored material comprises the following raw materials in parts by weight: 18 to 28 parts of rutile, 1 to 3 parts of ferrotitanium, 5 to 10 parts of potassium-sodium feldspar, 1 to 3 parts of zirconium dioxide, 3.5 to 6.5 parts of quartz, 3.5 to 6.5 parts of manganese monoxide, 1 to 3 parts of magnesia, 1.5 to 2.5 parts of ferroaluminum, 0.2 to 0.5 parts of fluoride, 15 to 20 parts of metallic chromium, 25 to 30 parts of nickel powder, 6 to 9 parts of molybdenum powder, and 1.5 to 10 parts of ferrotungsten. ~2.5 parts; the outer skin is a nickel-based alloy, and based on the total mass of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component: C≤0.02%, Mn≤1.0%, Fe:4.0~7.0%, Si≤0.08%, S≤0.04%, P≤0.02%, Cu≤0.50%, Co≤0.25%, Cr:14.5~16.5%, Mo:15.0~17.0%, W:3.0~4.0%, and the balance is Ni and unavoidable impurities.

[0029] The functions of the components in the drug core material of the present invention are as follows:

[0030] Rutile: The main component is TiO2. It forms uniform slag during welding, improves arc stability, and is the main powder material for welding wire to achieve good all-position welding operation. When the amount added is too little, the slag coverage is incomplete, and the vertical welding and overhead welding performance deteriorate. When the amount added is too much, slag inclusions are easily generated in the weld, which increases the oxygen content of the weld and deteriorates the mechanical properties of the deposited metal.

[0031] Quartz: The main component is SiO2, which increases the viscosity of the slag and makes the weld more beautiful. If the amount added is too little, the above effect cannot be achieved. If too much is added, the slag removal of the weld will deteriorate, and the Si content in the weld will increase, resulting in poor resistance to thermal cracking of the weld.

[0032] Manganese monoxide: an important additive in the flux-cored welding wire of the present application. Below 2400°C, on the one hand, it can transfer Mn elements to the weld, and on the other hand, it can cooperate with titanium iron and aluminum iron for deoxidation, reduce weld inclusions, and improve the low-temperature impact toughness and fracture toughness of the weld.

[0033] Ferro-titanium and ferro-aluminum: added as deoxidizers to reduce the oxygen content of the weld and improve the impact toughness of the weld. Ferro-aluminum can reduce the surface tension of the molten pool and improve wettability.

[0034] Potassium-sodium feldspar: added as arc stabilizer and slag-forming agent, the main components are Al2O3, K2O, Na2O, SiO2, adding a proper amount can stabilize the arc, adjust the slag viscosity, and improve the weld formation. Adding too much will increase the oxygen content in the weld and reduce the low-temperature impact toughness.

[0035] Zirconium dioxide and magnesia: The melting points of these two powders are relatively high, which can not only accelerate the solidification speed of welding slag, facilitate vertical welding and overhead welding operations, improve weld formation, but also enhance arc blowing force and achieve low current stable welding. If too much is added, the slag solidifies too quickly, the pores are not easy to escape, and pore defects are generated.

[0036] Fluoride: Its main function is to remove hydrogen from the weld. If too little is added, the effect is not obvious; if too much is added, the arc stability will be affected.

[0037] Metal chromium, nickel powder, molybdenum powder, and tungsten iron: added as alloying agents to transition alloy elements to the deposited metal to ensure that the weld has good mechanical properties.

[0038] In one embodiment, the filling factor of the flux core material is 20% to 22%, such as any value in the range of 20%, 21% or 22%. In the present application, the filling factor of the flux core material is the percentage of the weight of the flux core material to the total weight of the flux cored welding wire.

[0039] In one embodiment, the diameter of the flux-cored welding wire is 1.0-1.6 mm.

[0040] See also Figure 1 The preparation method of the core welding wire in the present application comprises the following steps:

[0041] S1. After drying the components of the core material, add them into a powder mixer and stir and mix them evenly to obtain a core material mixture;

[0042] S2, rolling the outer skin into a U-shaped groove;

[0043] S3, filling the core material mixture into the U-shaped groove;

[0044] S4. The U-shaped groove containing the core material mixture is closed, rolled into an O-shape, welded, and drawn to a set diameter.

[0045] In step S1, the core material includes the following raw materials in parts by weight: 18 to 28 parts of rutile, 1 to 3 parts of ferrotitanium, 5 to 10 parts of potassium-sodium feldspar, 1 to 3 parts of zirconium dioxide, 3.5 to 6.5 parts of quartz, 3.5 to 6.5 parts of manganese monoxide, 1 to 3 parts of magnesia, 1.5 to 2.5 parts of aluminum iron, 0.2 to 0.5 parts of fluoride, 15 to 20 parts of metallic chromium, 25 to 30 parts of nickel powder, 6 to 9 parts of molybdenum powder, and 1.5 to 2.5 parts of ferrotungsten. The drying temperature of rutile, feldspar and zirconium dioxide in the core material is 900-950°C, for example, 900°C, 920°C or 950°C, and the drying time is 6-8h, for example, 6h, 7h or 8h, and the drying temperature of the remaining components is 150-200°C, for example, 150°C, 180°C or 200°C, and the drying time is 2-3h, for example, 2h, 2.5h or 3h. The powder mixer can be any commonly used powder mixer in this field.

[0046] In step S2, the outer sheath of the flux-cored welding wire is a nickel-based alloy. Based on the total mass of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component: C≤0.02%, Mn≤1.0%, Fe:4.0-7.0%, Si≤0.08%, S≤0.04%, P≤0.02%, Cu≤0.50%, Co≤0.25%, Cr:14.5-16.5%, Mo:15.0-17.0%, W:3.0-4.0%, and the balance is Ni and unavoidable impurities.

[0047] In step S3, the filling factor of the core material is 20% to 22%, for example, any value within the range of 20% to 22%, such as 20%, 21% or 22%.

[0048] In step S4, the diameter of the flux-cored welding wire is 1.0-1.6 mm.

[0049] The technical scheme of the present invention is described in detail below through several specific examples. Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the examples are all commercially available.

[0050] Example 1

[0051] In this embodiment, the flux-cored welding wire for 9% Ni steel welding includes an outer skin and a flux core material wrapped in the outer skin, and the flux core material includes the following raw materials in weight: 20 parts of rutile, 2.5 parts of ferrotitanium, 7 parts of potassium-sodium feldspar, 2.5 parts of zirconium dioxide, 5.5 parts of quartz, 3.5 parts of manganese monoxide, 2 parts of magnesia, 2.2 parts of aluminum iron, 0.3 parts of fluoride, 17.8 parts of metal chromium, 26.5 parts of nickel powder, 8 parts of molybdenum powder, and 2.2 parts of ferrotungsten. The outer skin is made of nickel-based alloy, and based on the total mass of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component is: C content 0.02%, Mn content 0.8%, Fe content 5.0%, Si content 0.08%, S content 0.04%, P content 0.02%, Cu content 0.50%, Co content 0.25%, Cr content 16.5%, Mo content 16.0%, W content 3.0%, and the balance is Ni and unavoidable impurities.

[0052] First, the rutile, feldspar and zirconium dioxide in the above-mentioned core material are dried at 900°C for 8 hours, and the remaining components are dried at 200°C for 2 hours. Then, the components of the core material are added into a powder mixer and stirred and mixed evenly to obtain a core material mixture. The outer skin is rolled into a U-shaped groove, and the core material mixture is filled into the U-shaped groove. The U-shaped groove containing the core material mixture is closed, rolled into an O-shape, welded, and drawn to a set diameter.

[0053] In this embodiment, the fluoride is rare earth fluoride, and the filling rate of the core material is 20.8%.

[0054] Example 2

[0055] In this embodiment, the flux-cored welding wire for 9% Ni steel welding includes an outer skin and a flux core material wrapped in the outer skin, and the flux core material includes the following raw materials in weight: 25.5 parts of rutile, 2 parts of ferrotitanium, 5.6 parts of potassium-sodium feldspar, 1.5 parts of zirconium dioxide, 4.5 parts of quartz, 6 parts of manganese monoxide, 1.5 parts of magnesia, 1.8 parts of aluminum iron, 0.5 parts of fluoride, 16 parts of metal chromium, 27 parts of nickel powder, 6.5 parts of molybdenum powder, and 1.6 parts of tungsten iron. The outer skin is made of nickel-based alloy, and based on the total weight of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component is: C content 0.01%, Mn content 1%, Fe content 4.0%, Si content 0.05%, S content 0.01%, P content 0.015%, Cu content 0.40%, Co content 0.20%, Cr content 15.0%, Mo content 15.0%, W content 4.0%, and the balance is Ni and unavoidable impurities.

[0056] First, the rutile, feldspar and zirconium dioxide in the above-mentioned core material are dried at 920°C for 7 hours, and the remaining components are dried at 180°C for 2.5 hours. Then, the components of the core material are added into a powder mixer and stirred and mixed evenly to obtain a core material mixture. The outer skin is rolled into a U-shaped groove, and the core material mixture is filled into the U-shaped groove. The U-shaped groove containing the core material mixture is closed, rolled into an O-shape, welded, and drawn to a set diameter.

[0057] In this embodiment, the fluoride is fluorosilicate, and the filling rate of the core material is 20.6%.

[0058] Example 3

[0059] In this embodiment, the flux-cored welding wire for 9% Ni steel welding includes an outer skin and a flux core material wrapped in the outer skin, and the flux core material includes the following raw materials in parts by weight: 26.8 parts of rutile, 1.5 parts of ferrotitanium, 8 parts of potassium-sodium feldspar, 1.2 parts of zirconium dioxide, 3.5 parts of quartz, 4.5 parts of manganese monoxide, 2.5 parts of magnesia, 1.6 parts of aluminum iron, 0.4 parts of fluoride, 15.5 parts of metallic chromium, 25.5 parts of nickel powder, 7 parts of molybdenum powder, and 2 parts of ferrotungsten. The outer skin is made of nickel-based alloy. Based on the total mass of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component is: C content 0.015%, Mn content 0.9%, Fe content 7.0%, Si content 0.07%, S content 0.03%, P content 0.02%, Cu content 0.35%, Co content 0.23%, Cr content 14.5%, Mo content 17.0%, W content 3.8%, and the balance is Ni and unavoidable impurities.

[0060] First, the rutile, feldspar and zirconium dioxide in the above-mentioned core material are dried at 900°C for 8 hours, and the remaining components are dried at 150°C for 3 hours. Then, the components of the core material are added into a powder mixer and stirred and mixed thoroughly to obtain a core material mixture. The outer skin is rolled into a U-shaped groove, and the core material mixture is filled into the U-shaped groove. The U-shaped groove containing the core material mixture is closed, rolled into an O-shape, welded, and drawn to a set diameter.

[0061] In this embodiment, sodium fluoride is selected as the fluoride, and the filling rate of the core material is 21.2%.

[0062] Example 4

[0063] In this embodiment, the flux-cored welding wire for 9% Ni steel welding includes an outer skin and a flux core material wrapped in the outer skin, and the flux core material includes the following raw materials in weight: 18 parts of rutile, 3.0 parts of ferrotitanium, 8.3 parts of potassium-sodium feldspar, 1 part of zirconium dioxide, 6.5 parts of quartz, 5 parts of manganese monoxide, 3 parts of magnesia, 1.5 parts of aluminum iron, 0.2 parts of fluoride, 20 parts of metal chromium, 25 parts of nickel powder, 6 parts of molybdenum powder, and 2.5 parts of ferrotungsten. The outer skin is made of nickel-based alloy, and based on the total mass of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component is: C content 0.02%, Mn content 0.7%, Fe content 6.1%, Si content 0.078%, S content 0.034%, P content 0.018%, Cu content 0.45%, Co content 0.24%, Cr content 15.6%, Mo content 16.7%, W content 3.4%, and the balance is Ni and unavoidable impurities.

[0064] First, the rutile, feldspar and zirconium dioxide in the above-mentioned core material are dried at 950°C for 6 hours, and the remaining components are dried at 170°C for 1.8 hours. Then, the components of the core material are added into a powder mixer and stirred and mixed thoroughly to obtain a core material mixture. The outer skin is rolled into a U-shaped groove, and the core material mixture is filled into the U-shaped groove. The U-shaped groove containing the core material mixture is closed, rolled into an O-shape, welded, and drawn to a set diameter.

[0065] In this embodiment, potassium fluoride is selected as the fluoride, and the filling rate of the core material is 20%.

[0066] Example 5

[0067] In this embodiment, the flux-cored welding wire for 9% Ni steel welding includes an outer skin and a flux core material wrapped in the outer skin, and the flux core material includes the following raw materials in weight: 28 parts of rutile, 1 part of ferrotitanium, 5 parts of potassium-sodium feldspar, 1.8 parts of zirconium dioxide, 5 parts of quartz, 6.5 parts of manganese monoxide, 1 part of magnesia, 2 parts of aluminum iron, 0.2 parts of fluoride, 15 parts of metal chromium, 25 parts of nickel powder, 8 parts of molybdenum powder, and 1.5 parts of ferrotungsten. The outer skin is made of nickel-based alloy, and based on the total mass of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component is: C content 0.018%, Mn content 0.93%, Fe content 6.5%, Si content 0.069%, S content 0.033%, P content 0.017%, Cu content 0.39%, Co content 0.21%, Cr content 14.9%, Mo content 16.5%, W content 3.2%, and the balance is Ni and unavoidable impurities.

[0068] First, the rutile, feldspar and zirconium dioxide in the above-mentioned core material are dried at 930°C for 6.5 hours, and the remaining components are dried at 180°C for 2.5 hours. Then, the components of the core material are added into a powder mixer and stirred and mixed thoroughly to obtain a core material mixture. The outer skin is rolled into a U-shaped groove, and the core material mixture is filled into the U-shaped groove. The U-shaped groove containing the core material mixture is closed, rolled into an O-shape, welded, and drawn to a set diameter.

[0069] In this embodiment, the fluoride is a mixture of sodium fluoride and potassium fluoride, the mass ratio of sodium fluoride to potassium fluoride is 1:1, and the filling rate of the core material is 20%.

[0070] Example 6

[0071] In this embodiment, the flux-cored welding wire for 9% Ni steel welding includes an outer skin and a flux core material wrapped in the outer skin, and the flux core material includes the following raw materials in weight: 18.4 parts of rutile, 1.2 parts of ferrotitanium, 10 parts of potassium-sodium feldspar, 3 parts of zirconium dioxide, 3.5 parts of quartz, 3.5 parts of manganese monoxide, 1 part of magnesia, 2.5 parts of aluminum iron, 0.4 parts of fluoride, 16 parts of metal chromium, 30 parts of nickel powder, 9 parts of molybdenum powder, and 1.5 parts of ferrotungsten. The outer skin is made of nickel-based alloy, and based on the total mass of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component is: C content 0.018%, Mn content 0.95%, Fe content 5.8%, Si content 0.075%, S content 0.04%, P content 0.016%, Cu content 0.44%, Co content 0.23%, Cr content 15.1%, Mo content 16.3%, W content 3.6%, and the balance is Ni and unavoidable impurities.

[0072] First, the rutile, feldspar and zirconium dioxide in the above-mentioned core material are dried at 900°C for 8 hours, and the remaining components are dried at 170°C for 1.8 hours. Then, the components of the core material are added into a powder mixer and stirred and mixed thoroughly to obtain a core material mixture. The outer skin is rolled into a U-shaped groove, and the core material mixture is filled into the U-shaped groove. The U-shaped groove containing the core material mixture is closed, rolled into an O-shape, welded, and drawn to a set diameter.

[0073] In this embodiment, the fluoride is a mixture of fluorosilicate, sodium fluoride and potassium fluoride, the mass ratio of fluorosilicate, sodium fluoride and potassium fluoride is 1:1:1, and the filling rate of the core material is 22%.

[0074] Comparative Example 1

[0075] In this embodiment, the flux-cored welding wire for 9% Ni steel welding includes an outer skin and a flux core material wrapped in the outer skin, and the flux core material includes the following raw materials in weight: 28 parts of rutile, 2 parts of ferrotitanium, 6 parts of potassium-sodium feldspar, 1.8 parts of zirconium dioxide, 3.8 parts of quartz, 1 part of manganese monoxide, 2 parts of magnesia, 1.8 parts of aluminum iron, 0.4 parts of fluoride, 16.8 parts of metal chromium, 28 parts of nickel powder, 6.8 parts of molybdenum powder, and 1.6 parts of tungsten iron. The outer skin is made of nickel-based alloy, and based on the total mass of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component is: C content 0.016%, Mn content 0.7%, Fe content 6.1%, Si content 0.077%, S content 0.034%, P content 0.018%, Cu content 0.45%, Co content 0.24%, Cr content 15.6%, Mo content 16.7%, W content 3.4%, and the balance is Ni and unavoidable impurities.

[0076] First, the rutile, feldspar and zirconium dioxide in the above-mentioned core material are dried at 900°C for 8 hours, and the remaining components are dried at 150°C for 3 hours. Then, the components of the core material are added into a powder mixer and stirred and mixed thoroughly to obtain a core material mixture. The outer skin is rolled into a U-shaped groove, and the core material mixture is filled into the U-shaped groove. The U-shaped groove containing the core material mixture is closed, rolled into an O-shape, welded, and drawn to a set diameter.

[0077] In this comparative example, sodium fluoride is selected as the fluoride, and the filling rate of the core material is 21.1%.

[0078] Comparative Example 2

[0079] In this embodiment, the flux-cored welding wire for 9% Ni steel welding includes an outer skin and a flux core material wrapped in the outer skin, and the flux core material includes the following raw materials in parts by weight: 15 parts of rutile, 2.8 parts of ferrotitanium, 8.5 parts of potassium-sodium feldspar, 2 parts of zirconium dioxide, 6 parts of quartz, 5.5 parts of manganese monoxide, 2.8 parts of magnesia, 2.2 parts of ferroaluminum, 0.5 parts of fluoride, 19.2 parts of metallic chromium, 27.5 parts of nickel powder, 6 parts of molybdenum powder, and 2 parts of ferrotungsten. The outer skin is made of nickel-based alloy. Based on the total mass of the nickel-based alloy, the nickel-based alloy includes the following components and the mass percentage of each component is: C content 0.019%, Mn content 0.93%, Fe content 6.5%, Si content 0.069%, S content 0.033%, P content 0.017%, Cu content 0.39%, Co content 0.21%, Cr content 14.9%, Mo content 16.5%, W content 3.2%, and the balance is Ni and unavoidable impurities.

[0080] First, the rutile, feldspar and zirconium dioxide in the above-mentioned core material are dried at 950°C for 6 hours, and the remaining components are dried at 170°C for 1.8 hours. Then, the components of the core material are added into a powder mixer and stirred and mixed thoroughly to obtain a core material mixture. The outer skin is rolled into a U-shaped groove, and the core material mixture is filled into the U-shaped groove. The U-shaped groove containing the core material mixture is closed, rolled into an O-shape, welded, and drawn to a set diameter.

[0081] In this embodiment, potassium fluoride is selected as the fluoride, and the filling rate of the core material is 20.8%.

[0082] The core material components of the flux-cored welding wires prepared in Examples 1 to 6 and Comparative Examples 1 and 2 in the present application are shown in the table. The flux-cored welding wires prepared in Examples 1 to 6 and Comparative Examples 1 and 2 are used for test plate welding, with a welding current of 180A, a welding voltage of 25V, a shielding gas of 80% Ar+20% CO2, and process performance and mechanical properties of vertical welding position welding as shown in Table 2.

[0083] Table 1: Core material components of the cored welding wires prepared in Examples 1 to 6 and Comparative Examples 1 and 2

[0084]

[0085]

[0086] Table 2: Processing performance and mechanical properties of vertical welding position of flux-cored welding wire prepared in Examples 1 to 6 and Comparative Examples 1 and 2

[0087]

[0088] It can be seen from the data in Table 2 that the flux-cored welding wires prepared in Examples 1 to 6 have good welding processability and mechanical properties, and are suitable for welding 9% Ni steel.

[0089] The flux-cored welding wire for 9% Ni steel welding provided by the present invention, by adding manganese monoxide to the flux-cored material, can further reduce the oxygen content of the weld and reduce the porosity sensitivity on the basis of the combined deoxidation of titanium iron and aluminum iron; the steel strip is a nickel-based alloy steel strip with C≤0.02%, which further reduces the generation of CO gas. Since the amount of CO generated during welding is reduced, the proportion of slag-forming agent in the flux-cored material can be appropriately increased to adjust the slag viscosity. The slag-forming agent of the present application selects TiO2-SiO2-ZrO2-Al2O3-MgO for combined slag-forming, which achieves excellent all-position welding operating performance, especially the molten pool is not easy to fall during vertical welding and overhead welding, and the weld is more beautiful and has better mechanical properties. Therefore, the present invention effectively overcomes some practical problems in the prior art and thus has high utilization value and use significance.

[0090] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A flux core material for 9% Ni steel welding, characterized in that: The core material comprises the following raw materials in parts by weight: 18 to 28 parts of rutile, 1 to 3 parts of ferrotitanium, 5 to 10 parts of potassium-sodium feldspar, 1 to 3 parts of zirconium dioxide, 3.5 to 6.5 parts of quartz, 3.5 to 6.5 parts of manganese monoxide, 1 to 3 parts of magnesia, 1.5 to 2.5 parts of ferroaluminum, 0.2 to 0.5 parts of fluoride, 15 to 20 parts of metallic chromium, 25 to 30 parts of nickel powder, 6 to 9 parts of molybdenum powder, and 1.5 to 2.5 parts of ferrotungsten.

2. The flux core material for 9% Ni steel welding according to claim 1, characterized in that: The fluoride includes any one or more of rare earth fluoride, fluorosilicate, sodium fluoride and potassium fluoride.

3. The flux core material for 9% Ni steel welding according to claim 1, characterized in that: The rutile, the potassium-sodium feldspar and the quartz are respectively sieved through an 80-mesh sieve.

4. The flux core material for 9% Ni steel welding according to claim 1, characterized in that: The metallic chromium, the nickel powder, the molybdenum powder and the tungsten iron are respectively sieved through a 120-mesh sieve.

5. The flux core material for 9% Ni steel welding according to claim 1, characterized in that: The S content in all raw materials of the drug core material is ≤0.02%, and the P content is ≤0.02%.

6. A flux-cored welding wire for welding 9% Ni steel, characterized in that: The invention comprises an outer skin and a core material coated in the outer skin, wherein the core material comprises the following raw materials in parts by weight: 18 to 28 parts of rutile, 1 to 3 parts of ferrotitanium, 5 to 10 parts of potassium-sodium feldspar, 1 to 3 parts of zirconium dioxide, 3.5 to 6.5 parts of quartz, 3.5 to 6.5 parts of manganese monoxide, 1 to 3 parts of magnesia, 1.5 to 2.5 parts of aluminum iron, 0.2 to 0.5 parts of fluoride, 15 to 20 parts of metallic chromium, 25 to 30 parts of nickel powder, 6 to 9 parts of molybdenum powder, and 1.5 to 2.5 parts of ferrotungsten; the outer skin The nickel-based alloy comprises the following components and the mass percentage of each component based on the total mass of the nickel-based alloy: C≤0.02%, Mn≤1.0%, Fe:4.0-7.0%, Si≤0.08%, S≤0.04%, P≤0.02%, Cu≤0.50%, Co≤0.25%, Cr:14.5-16.5%, Mo:15.0-17.0%, W:3.0-4.0%, and the balance is Ni and unavoidable impurities.

7. The flux-cored welding wire for welding 9% Ni steel according to claim 6, characterized in that: The filling factor of the medicine core material is 20% to 22%.

8. The flux-cored welding wire for welding 9% Ni steel according to claim 6, characterized in that: The diameter of the flux-cored welding wire is 1.0-1.6 mm.

9. A method for preparing a flux-cored welding wire for welding 9% Ni steel according to any one of claims 6 to 8, characterized in that: The steps include: After drying the components of the drug core material, add them into a powder mixer and stir and mix them evenly to obtain a drug core material mixture; Roll the outer skin into a U-shaped groove; Filling the drug core material mixture into the U-shaped groove; The U-shaped groove containing the core material mixture is closed, rolled into an O-shaped shape, welded, and drawn to a set diameter.

10. The method for preparing a flux-cored welding wire according to claim 9, characterized in that: The drying temperature of rutile, feldspar and zirconium dioxide in the core material is 900-950° C., and the drying time is 6-8 hours. The drying temperature of other components is 150-200° C., and the drying time is 2-3 hours.

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