Low-cobalt stainless steel flux-cored wire and preparation method thereof

Abstract

The invention relates to the technical field of stainless steel flux-cored wires, in particular to a low-cobalt stainless steel flux-cored wire and a preparation method thereof. Refined nickel produced by taking nickel laterite as a raw material is relatively high in Co content and is directly used as a nickel source for producing a 309L stainless steel flux-cored wire for nuclear power pressure vessel welding, when the nickel content in obtained weld cladding metal reaches 12-14%, the Co content in the weld cladding metal is difficult to be less than or equal to 0.20%, and the corrosion resistance of the obtained weld is poor. In order to solve the technical problems, the low-cobalt stainless steel flux-cored wire is provided, the composition and content of the flux-cored wire are reasonably adjusted, aluminum oxide and titanium dioxide are added into the core wire components at the same time to serve as main Co-removing components, meanwhile, the welding heat cycle principle is utilized, and under the condition that the mechanical strength of a welding seam is not reduced, the low-cobalt stainless steel flux-cored wire is obtained. And the Co content in the obtained welding seam cladding metal is effectively reduced, and it is ensured that the welding seam has good comprehensive performance such as corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of stainless steel flux-cored welding wires, and in particular to a low-cobalt stainless steel flux-cored welding wire and a preparation method thereof. Background Art

[0002] Due to the depletion of global nickel sulfide ore resources and rising prices (LME nickel prices rose by 150% between 2020 and 2023), the industry has gradually turned to nickel laterite as the main nickel source. However, cobalt and nickel in laterite are naturally associated, with a Co / Ni mass ratio as high as 0.05-0.15, resulting in a significant increase in the cobalt content in the extracted nickel raw material (typical value: Co content in laterite refined nickel is 0.3%-0.6%).

[0003] When using refined nickel produced from laterite nickel sources to manufacture 309L stainless steel flux-cored welding wire for nuclear power plants, sufficient nickel powder must be added to meet the nickel content standard for the cladding metal (ASME III requires 12%-14%). However, the cobalt introduced in this way causes the mass percentage of Co in the cladding metal to reach 0.25%-0.45%, far exceeding the cobalt content limit for cladding metals set by nuclear power safety standards (≤0.20%). Excessive cobalt in the cladding metal can cause the following serious problems:

[0004] Intergranular corrosion acceleration: Co promotes Cr in the ferrite phase 23 The preferential precipitation of C6 carbides (precipitation rate increased by 30% to 50%) causes the width of the chromium-depleted zone to expand to 50 to 80 nm, and the intergranular corrosion rate increases by 2 to 3 times (tested according to ASTM G28 standard);

[0005] Deterioration of pitting corrosion resistance: The synergistic effect of Co and Cl- causes the pitting potential (Epit) to drop from +350mV to +250mV (according to ASTMG61 standard), and the critical Cl- concentration for pitting initiation is reduced from 0.1mol / L to 0.05mol / L;

[0006] Degradation of mechanical properties: tensile strength of cladding metal <520MPa (ASME III requires ≥550MPa), intergranular corrosion test pass rate ≤70% (nuclear power standard requires ≥95%).

[0007] Although traditional hydrometallurgical processes (such as high-pressure acid leaching (HPAL)) can separate nickel and cobalt, due to the similar chemical properties of cobalt and nickel in laterite ores, the separation efficiency is limited (the residual Co content in the final welding wire still reaches 0.15%-0.25%), and the process cost is high.

[0008] The industry has tried to reduce the amount of cobalt introduced by reducing the amount of nickel added (for example, reducing the nickel content to 10%-11%), but this approach can easily lead to:

[0009] Insufficient austenite stability: The ferrite content in the cladding metal is >10% (determined by metallographic method), which triggers the γ→α' phase transformation tendency and reduces the low-temperature impact toughness by 40%;

[0010] Corrosion resistance deterioration: The depth of the chromium-depleted zone in the intergranular corrosion test is >5μm (the qualified threshold is ≤2μm), resulting in a shortening of the container life by more than 30%;

[0011] Violation of standard specifications: Failure to meet the ASME III mandatory requirement of 12%-14% nickel content limits its application in the nuclear power field.

[0012] The core contradiction currently facing the industry is how to strictly control the cobalt content in the weld cladding metal to ≤0.20% while ensuring that the nickel content of the weld cladding metal meets the standard (12%-14%). Summary of the Invention

[0013] A problem with the prior art is that the refined nickel produced from nickel laterite ore has a high Co content. When directly used as a nickel source for producing 309L stainless steel flux-cored welding wire for nuclear power pressure vessels, the resulting weld metal cladding, when containing 12%-14% nickel, struggles to maintain a Co content of ≤0.20%, resulting in poor corrosion resistance. To address this issue, the present invention provides a low-cobalt stainless steel flux-cored welding wire comprising a core powder and an iron sheet, wherein the iron sheet is a stainless steel strip. The core powder has a filling rate of 22-28% within the iron sheet. The core powder comprises the following components, by weight:

[0014]

[0015] The stainless steel strip comprises the following elements in terms of mass percentage:

[0016]

[0017] Cobalt 0.03-0.05%;

[0018] Aluminum 0.01-0.03%;

[0019] Titanium 0.05-0.1%;

[0020] Nitrogen 0.2-0.4%;

[0021] The balance is iron.

[0022] Preferably, the metal element powder includes one or a combination of two or more of iron powder, aluminum powder and magnesium powder.

[0023] Preferably, the slag-forming agent includes one or a combination of two or more of rutile, fluorite and marble.

[0024] Preferably, the fluoride includes cryolite, sodium fluoride, magnesium fluoride, or a combination of two or more thereof.

[0025] Preferably, the metal oxide is a mixture of silicon dioxide, titanium dioxide and aluminum oxide in a mass ratio of 5:2:3.

[0026] Preferably, the deslagging agent comprises bismuth oxide, calcium oxide or a combination of both.

[0027] Preferably, the alloying agent comprises manganese powder, chromium powder and nickel powder, and the mass ratio of manganese powder to chromium powder and nickel powder in the alloying agent is 4-6:19-24:18-22.

[0028] Preferably, the arc stabilizer includes one or a mixture of two or more of potassium titanate, sodium titanate, potassium chloride, sodium chloride, and potassium feldspar powder.

[0029] Preferably, the rare earth fluoride includes one or both of LaF3 and CeF3.

[0030] The preparation method of the low-cobalt stainless steel flux-cored welding wire comprises the following steps:

[0031] (1) Roll the stainless steel strip into a U-shape and add the formulated amount of welding core powder into the U-shaped groove;

[0032] (2) The U-shaped groove is rolled into an O-shaped steel pipe, and then rolled, bright annealed, drawn and reduced, and mechanically cleaned to obtain a low-cobalt stainless steel flux-cored welding wire with a diameter of Φ = 1.2-1.6 mm.

[0033] The principles of the present invention are as follows:

[0034] (1) On the one hand, the present invention controls the addition amount of Ni to a relatively low level when processing stainless steel strips, and slightly increases the addition amount of Mn and N elements in the stainless steel strips, thereby ensuring the formation ability of austenite during the welding wire cladding process, effectively ensuring the proportion of austenite in the weld cladding metal and the strength of the weld. At the same time, the content of C element can be increased to improve the strength of the weld cladding metal, but the increase in C content is likely to produce Cr in the weld cladding metal. 23 C6, which causes Cr-poor areas to appear at the grain boundaries, making pitting corrosion more likely to occur;

[0035] (2) On the other hand, during the high-temperature welding metallurgy process, Co and Ni are mutually soluble and have a strong bonding force with Fe. Under the conditions of instantaneous high-temperature metallurgy, Co is easily precipitated from Ni and oxidized to form CoO. In order to prevent CoO from being reduced by the Fe matrix to form CoFe alloy and enter the weld matrix, the present invention adds TiO2 to the welding core powder component. During the high-temperature welding metallurgy process, TiO2 will decompose into free Ti and O. Ti is more reducible than Fe and can preferentially reduce CoO to obtain free Co atoms. Compared with the Fe matrix, Co is more easily combined with B and Al to form Co-B compounds and Co-Al compounds. The melting point of Co-B compounds is 1400℃-1500℃ and they are brittle. The melting point of Co-Al compounds is 1400℃-1500℃. The melting point of Al-B compound is about 1650℃, the structure is loose and porous, and the density is small. At the same time, Al-B compound will be formed in the high-temperature welding metallurgy process. The melting point of Al-B compound is about 1650℃, the structure is loose, and the density is very small. In the rapid cooling process of high-temperature metallurgical welding, the Co-Al and Al-B compounds with smaller density will precipitate first and float to the upper surface of the molten pool, and the Co-B compound will precipitate later. Both Co-B and B-Al have cubic structures, and the binding force between the two is strong. In the precipitation process of Co-B compound, the Co-Al and Al-B compounds on the surface of the molten pool are used as nuclei, and the generated Co-B compound adheres to the surface of Co-Al and Al-B compounds and enters the slag together, thereby effectively reducing the Co content in the weld cladding metal;

[0036] (3) When the molten pool temperature is further reduced to about 1400℃, Co and Ti will form a Co-Ti compound with a lower density. At this time, the weld pool will immediately begin to solidify (the melting point of the weld metal is about 1350℃). However, under the action of the welding thermal cycle, the previous weld will be reheated during the next welding, stirring the molten pool. At this time, the process of Co-Al, Al-B, and Co-B entering the slag in sequence will reoccur, and Co-Ti will precipitate last, carrying the CoB remaining on the surface of the molten pool into the slag from below, further ensuring the effective reduction of the Co content in the weld.

[0037] (4) During the slag removal process, Al-B is removed together, removing excess B, which can effectively avoid the segregation of B at the grain boundary caused by the addition of B elements, thereby increasing the brittleness of the weld cladding metal and the tendency to form hot cracks;

[0038] (5) The present invention adds chloride to the core powder component. The chloride in the welding metallurgy process - It combines with Co to form CoCl2 high-temperature gas, thereby reducing the content of Co element. However, under the metallurgical conditions of rapid heating and cooling during welding, this principle has little effect.

[0039] The components of the welding core powder of the present invention play the following roles in the welding process:

[0040] Ferroboron alloy powder adds B element to the molten pool metal during the welding process.

[0041] Zirconium-iron alloy powder forms ZrO2 during the welding process, which can increase the melting point of the weld slag and enhance the formability of the weld metal. It has a large linear expansion coefficient, which is conducive to the shedding of the slag and weld metal during cooling.

[0042] Manganese powder interacts with SiO2 during the welding process, and Si-Mn jointly deoxidizes, effectively reducing the oxygen content in the weld pool metal and supplementing the alloy components.

[0043] Chromium powder mainly realizes the transition of Cr element during the welding process and supplements the alloy composition of weld metal.

[0044] Nickel powder mainly realizes the transition of Ni element during welding and supplements the alloy composition of weld metal.

[0045] Iron powder mainly improves the welding efficiency of the welding wire during the welding process, stabilizes the transition of the welding metal droplets, and reduces spatter during welding.

[0046] Aluminum powder can reduce oxides during the welding process, protect transition metals such as Ti and B, and reduce their burning loss.

[0047] Magnesium powder can deoxidize during the welding process, reduce the oxygen element in the weld metal, and at the same time reduce the arc ionization voltage to stabilize the arc starting of the welding wire.

[0048] Silicon dioxide works together with Mn during the welding process to achieve Si-Mn joint deoxidation. At the same time, SiO2 can form slag and improve the viscosity of the slag, making it easier to fall off.

[0049] Titanium dioxide realizes the transition of Ti element during welding.

[0050] Alumina can promote the formation of slag and improve the fluidity of slag during welding, reduce slag inclusion, and participate in the chemical reaction of the Co removal process.

[0051] Fluoride can form HF during the welding process, reducing the H content in the weld metal and reducing the possibility of defects such as hydrogen embrittlement and pitting corrosion.

[0052] Rare earth fluorides improve weld performance, purify the molten pool, and reduce the content of impurities (such as oxygen, sulfur, and phosphorus) in the weld metal during the welding process.

[0053] Rutile stabilizes the arc during welding, forms slag to protect the weld pool, refines the molten droplets, and reduces spatter during welding.

[0054] Fluorite can adjust the surface tension of the liquid metal in the weld pool during welding, reduce the porosity, improve slag coverage, and protect the molten pool metal.

[0055] Marble increases the basicity of slag during welding, reduces the S and P content in the weld metal, and improves the crack resistance of the weld metal.

[0056] Potassium titanate reduces the ionization voltage during welding and improves arc stability.

[0057] Sodium titanate reduces the ionization voltage during welding and improves the stability of the arc.

[0058] Potassium chloride reduces the ionization voltage during welding and provides Cl - The particles combine with Co at high temperature to form CoCl2 high-temperature gas.

[0059] Sodium chloride reduces the ionization voltage during welding and provides Cl - The particles combine with Co at high temperature to form CoCl2 high-temperature gas.

[0060] Potash feldspar powder stabilizes the arc during welding, reduces spatter, enhances the wettability of the weld metal, and improves welding efficiency.

[0061] Bismuth oxide can undergo allotropic transformation of some oxides during the welding process, making the slag brittle and easy to fall off.

[0062] Calcium oxide forms fusible compounds during welding, which removes surface oxides and makes slag easy to remove.

[0063] The present invention has the following beneficial effects:

[0064] (1) In the welding metallurgical process, the present invention preferentially reduces CoO through Ti, and converts Co into Co-B compounds through B in the molten pool. At the same time, Al-Co compounds and Al-B compounds are used to form and adsorb Co-B compounds into the slag. At the same time, according to the difference in melting points, the Co-Ti compound secondary adsorbs the Co-B compound and carries it into the slag using the welding thermal cycle principle, forming a brittle slag that is easier to fall off, effectively reducing the Co content in the weld deposited metal while ensuring the comprehensive performance of the weld deposited metal structure, such as corrosion resistance;

[0065] (2) The present invention is suitable for all-position welding, with beautiful weld formation, small spatter, and excellent slag removal performance. Specific implementation method:

[0066] The present invention will be described in detail below with reference to the following examples. However, it should be understood that the following examples are merely illustrative of the embodiments of the present invention and are not intended to limit the scope of the present invention.

[0067] The ferroboron alloy powder used in the following embodiments of the present invention is FeB20, which has the following composition: 20% B, 0.5% C, 0.1% Si, 0.2% Al, and the remainder being Fe and unavoidable impurities.

[0068] The grade of the ferro-zirconium alloy powder used in the following examples of the present invention is FeZr80.

[0069] The purity of cryolite (sodium hexafluoroaluminate), rutile (TiO2), fluorite (CaF2), and marble (CaCO3) in the following examples of the present invention is 97%.

[0070] The metal oxide in the following Example 1 of the present invention is composed of silicon dioxide, titanium dioxide, and aluminum oxide in a mass ratio of 5:2:3.

[0071] The nickel powder composition in the following examples of the present invention has a Ni content of 99.4% by mass, a Co content of 0.5% by mass, and the remainder being impurities.

[0072] Example 1

[0073] A low-cobalt stainless steel flux-cored welding wire with a diameter of Φ=1.2, which is composed of welding core powder and iron sheet. The iron sheet is a stainless steel strip with a thickness of 0.4 mm. The filling rate of the welding core powder in the iron sheet is 25%. The welding core powder has the following composition by weight:

[0074]

[0075]

[0076] The metal element powder is composed of magnesium powder, iron powder and aluminum powder in a mass ratio of 1:6:3;

[0077] The alloying agent is composed of manganese powder, chromium powder and nickel powder in a mass ratio of 4:20:22; the arc stabilizing agent is composed of potassium titanate and sodium chloride powder in a mass ratio of 3:1;

[0078] The slagging agent is composed of rutile and fluorite in a mass ratio of 20:3;

[0079] The rare earth fluoride is composed of LaF3 and CeF3 in a mass ratio of 3:2.

[0080] The stainless steel strip has the following composition in terms of mass percentage:

[0081]

[0082] The preparation method of the low-cobalt stainless steel flux-cored welding wire is as follows:

[0083] (1) Roll the stainless steel strip into a U-shape and add the formulated amount of welding core powder into the U-shaped groove;

[0084] (2) The U-shaped groove is rolled into an O-shaped steel pipe, and then rolled, bright annealed, drawn and reduced, and mechanically cleaned to obtain a low-cobalt stainless steel flux-cored welding wire.

[0085] Example 2

[0086] A low-cobalt stainless steel flux-cored welding wire with a diameter of Φ=1.2, which is composed of welding core powder and iron sheet. The iron sheet is a stainless steel strip with a thickness of 0.4 mm. The filling rate of the welding core powder in the iron sheet is 23%. The welding core powder has the following composition by weight:

[0087]

[0088] The metal element powder is composed of iron powder and magnesium powder in a mass ratio of 3:2;

[0089] The alloying agent is composed of manganese powder, chromium powder and nickel powder in a mass ratio of 5:24:21;

[0090] The arc stabilizer is composed of sodium titanate and potassium chloride in a mass ratio of 3:2;

[0091] The slag-making agent is composed of fluorite and marble in a mass ratio of 3:1;

[0092] The rare earth fluoride is LaF3.

[0093] The stainless steel strip has the following composition in terms of mass percentage:

[0094]

[0095]

[0096] The preparation method of the low-cobalt stainless steel flux-cored welding wire is as follows:

[0097] (1) Roll the stainless steel strip into a U-shape and add the formulated amount of welding core powder into the U-shaped groove;

[0098] (2) The U-shaped groove is rolled into an O-shaped steel pipe, and then rolled, bright annealed, drawn and reduced, and mechanically cleaned to obtain a low-cobalt stainless steel flux-cored welding wire.

[0099] Example 3

[0100] A low-cobalt stainless steel flux-cored welding wire with a diameter of Φ=1.2, which is composed of welding core powder and iron sheet. The iron sheet is a stainless steel strip with a thickness of 0.4 mm. The filling rate of the welding core powder in the iron sheet is 28%. The welding core powder has the following composition by weight:

[0101]

[0102]

[0103] The metal element powder is composed of aluminum powder and iron powder in a mass ratio of 1:1;

[0104] The alloying agent is composed of manganese powder, chromium powder and nickel powder in a mass ratio of 5:19:18;

[0105] The arc stabilizer is composed of sodium titanate and potassium feldspar powder in a mass ratio of 3:1;

[0106] The slagging agent is composed of rutile and marble in a mass ratio of 22:3;

[0107] The rare earth fluoride is CeF3.

[0108] The stainless steel strip has the following composition in terms of mass percentage:

[0109]

[0110] The preparation method of the low-cobalt stainless steel flux-cored welding wire is as follows:

[0111] (1) Roll the stainless steel strip into a U-shape and add the formulated amount of welding core powder into the U-shaped groove;

[0112] (2) The U-shaped groove is rolled into an O-shaped steel pipe, and then rolled, bright annealed, drawn and reduced, and mechanically cleaned to obtain a low-cobalt stainless steel flux-cored welding wire.

[0113] Example 4

[0114] A low-cobalt stainless steel flux-cored welding wire with a diameter of Φ=1.2, which is composed of welding core powder and iron sheet. The iron sheet is a stainless steel strip with a thickness of 0.4 mm. The filling rate of the welding core powder in the iron sheet is 22%. The welding core powder has the following composition by weight:

[0115]

[0116] The metal element powder is composed of aluminum powder and magnesium powder in a mass ratio of 1:2;

[0117] The alloying agent is composed of manganese powder, chromium powder and nickel powder in a mass ratio of 4:21:20;

[0118] The arc stabilizer is composed of sodium chloride and potassium feldspar powder in a mass ratio of 7:2;

[0119] The slag-making agent is composed of fluorite and marble in a mass ratio of 13:7;

[0120] The rare earth fluoride is composed of LaF3 and CeF3 in a mass ratio of 3:1.

[0121] The stainless steel strip has the following composition in terms of mass percentage:

[0122]

[0123]

[0124] The preparation method of the low-cobalt stainless steel flux-cored welding wire is as follows:

[0125] (1) Roll the stainless steel strip into a U-shape and add the formulated amount of welding core powder into the U-shaped groove;

[0126] (2) The U-shaped groove is rolled into an O-shaped steel pipe, and then rolled, bright annealed, drawn and reduced, and mechanically cleaned to obtain a low-cobalt stainless steel flux-cored welding wire.

[0127] Comparative Example 1 is the same as Example 1, except that no ferroboron alloy powder is added in Comparative Example 1.

[0128] Comparative Example 2 is the same as Example 1, except that the amount of ferroboron alloy powder added in Comparative Example 2 is too high. The composition of the welding core powder is as follows by weight:

[0129]

[0130] Comparative Example 3 is the same as Example 1, except that the metal oxide in Comparative Example 3 is composed of silicon dioxide and aluminum oxide in a mass ratio of 5:5.

[0131] Comparative Example 4 is the same as Example 1, except that the metal oxide in Comparative Example 4 is composed of silicon dioxide and titanium dioxide in a mass ratio of 5:5.

[0132] Comparative Example 5 is the same as Example 1, except that the metal oxide in Comparative Example 5 is composed of silicon dioxide, titanium dioxide, and aluminum oxide in a mass ratio of 5:1:4.

[0133] Comparative Example 6 is the same as Example 1, except that the metal oxide in Comparative Example 6 is composed of silicon dioxide, titanium dioxide, and aluminum oxide in a mass ratio of 5:4:1.

[0134] Comparative Example 7 is the same as Example 1, except that the metal oxide in Comparative Example 7 is composed of silicon dioxide, titanium dioxide, and aluminum oxide in a mass ratio of 3:2:5.

[0135] Comparative Example 8 is the same as Example 1, except that the stainless steel strip used in Comparative Example 8 has the following composition, calculated by mass percentage:

[0136]

[0137] Performance Testing: P265GH steel plates were overlay welded using the flux-cored welding wires obtained in Examples 1-4 of the present invention and Comparative Examples 1-8, and the resulting weld cladding metals were subjected to relevant performance tests. Each parallel experiment was tested 10 times, and the average value was taken. The specific test results are shown in Tables 1, 2, 2, and 3. The compositions of the weld cladding metals obtained by overlay welding the flux-cored welding wires obtained in Examples 1-4 of the present invention and Comparative Examples 1-8 under different gas shielding conditions are shown in Tables 1-3. The flux-cored welding wires obtained in Examples 1-4 of the present invention and Comparative Examples 1-8 were overlay welded under pure CO2 protection for five layers, with three passes per layer. The element contents of Co, Ni, Mn, N, Mo, and Cr in the resulting weld cladding metals are shown in Tables 4 and 4.

[0138] Weld deposited metal, tensile strength: the test standard is GB / T 228-2021.

[0139] Weld deposited metal, elongation at break: the test standard is GB / T 228-2121.

[0140] Weld deposited metal, impact energy: the test standard is GB / T 229-2020.

[0141] Bending performance: The test standard is GB / T 232-2010.

[0142] Intergranular corrosion: The test standard is method B in the Q1GB / T4334-2020 "Corrosion of metals and alloys - Test method for intergranular corrosion of austenitic and ferritic-austenitic (duplex) stainless steels".

[0143] Table 1

[0144]

[0145] Table 2

[0146]

[0147] Table 2

[0148]

[0149] Table 3

[0150]

[0151] Table 4

[0152]

[0153] Table 4

[0154]

[0155] From the above test data, we can see that

[0156] In Examples 1-4, the Co content in the weld cladding metal was significantly reduced, resulting in stronger intergranular corrosion resistance and stronger cladding metal performance. In Comparative Examples 1-8, the weld cladding metal had good impact resistance and ductility, but the Co content was relatively high, resulting in poor corrosion resistance of the weld.

[0157] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A low cobalt stainless steel flux-cored welding wire, characterized in that: The invention comprises welding core powder and iron sheet, wherein the iron sheet is a stainless steel strip, the filling rate of the welding core powder in the iron sheet is 22-28%, the mass percentage of Ni in the stainless steel strip is 7-8%, the mass percentage of Co is 0.03-0.05%, the mass percentage of manganese is 1-1.5%, and the mass percentage of nitrogen is 0.2-0.4%; The welding core powder comprises the following components by weight: 1-5% ferroboron alloy powder; Zirconium-iron alloy powder 1-2%; Metal element powder 5-15%; Slag forming agent 10-30%; Fluoride 3-4%; Metal oxides 10-15%; Deslagging agent 0.2-0.5%; Deoxidizer 3-12%; Alloying agent 30-52%; Arc stabilizer 4-5%; Rare earth fluoride 0.5-3%.

2. A low cobalt stainless steel flux-cored welding wire according to claim 1, characterized in that: The metal element powder includes one or a combination of two or more of iron powder, aluminum powder and magnesium powder.

3. The low cobalt stainless steel flux-cored welding wire according to claim 1, characterized in that: The slag-forming agent comprises one or a combination of two or more of rutile, fluorite and marble.

4. The low cobalt stainless steel flux-cored welding wire according to claim 1, characterized in that: The fluoride includes one or a combination of two or more of cryolite, sodium fluoride and magnesium fluoride.

5. The low cobalt stainless steel flux-cored welding wire according to claim 1, characterized in that: The metal oxide is a mixture of silicon dioxide, titanium dioxide and aluminum oxide in a mass ratio of 5:2:

3.

6. The low cobalt stainless steel flux-cored welding wire according to claim 1, characterized in that: The deslagging agent includes bismuth oxide, calcium oxide or a combination of the two.

7. The low cobalt stainless steel flux-cored welding wire according to claim 1, characterized in that: The alloying agent includes manganese powder, chromium powder and nickel powder. The mass ratio of manganese powder to chromium powder and nickel powder in the alloying agent is 4-6:19-24:18-22.

8. The low cobalt stainless steel flux-cored welding wire according to claim 1, characterized in that: The arc stabilizer includes one or a mixture of two or more of potassium titanate, sodium titanate, potassium chloride, sodium chloride, and potassium feldspar powder.

9. The low cobalt stainless steel flux-cored welding wire according to claim 1, characterized in that: The stainless steel strip comprises the following elements in terms of mass percentage:

10. A low-cobalt stainless steel flux-cored welding wire according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: (1) Roll the stainless steel strip into a U-shape and add the formulated amount of welding core powder into the U-shaped groove; (2) The U-shaped groove is rolled into an O-shaped steel pipe, and then rolled, bright annealed, drawn and reduced, and mechanically cleaned to obtain a low-cobalt stainless steel flux-cored welding wire with a diameter of Φ = 1.2-1.6 mm.

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