900mpa grade non-magnetic chlorine ion corrosion resistant stainless steel welding wire and preparation method

Abstract

900MPa grade non-magnetic stainless steel welding wire with chlorine ion corrosion resistance and preparation method, belong to metallurgical technical field.The welding wire chemical composition and mass content are C≤00.02%, Si: 0.40~0.50%, Mn: 13~17%, Cr: 18~23%, Ni≤0.3%, Mo: 4.5~6.5%, N: 0.55~0.75%, Cu: 0.20~0.40%, La: 0.02~0.06%, Mg: 0.03~0.06%, P≤100ppm, S≤100ppm, the balance is iron and inevitable impurities;Its preparation method includes non-vacuum induction furnace smelting, electroslag remelting, forging, rolling, solid solution + pickling, drawing process.The welding wire has non-magnetic characteristics after welding, the tensile strength reaches 900MPa or more, and the corrosion rate in 6% FeCl3 hydrochloric acid solution is less than 0.2g / m 2 *h.

Description

Technical Field

[0001] This invention belongs to the field of welding materials technology, specifically relating to 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire and its preparation method. Background Technology

[0002] Austenitic stainless steel possesses non-magnetic properties and good ductility and toughness, but its strength is relatively low and cannot be strengthened through phase transformation; its strength can only be improved through cold working. However, in some special environments, such as the petroleum and chemical industries, certain connectors or pressure vessels require non-magnetic properties, high strength, and resistance to chloride ion corrosion. Therefore, for welded parts, high strength and resistance to chloride ion corrosion are required, demanding tensile strengths of 850-900 MPa or higher at the weld joint. This places higher demands on related welding materials. Conventional austenitic stainless steel welding wires cannot meet these requirements. Martensitic and duplex stainless steels can achieve high strength under certain conditions, but they cannot meet the non-magnetic requirement, necessitating the use of expensive nickel-based alloys and some super austenitic stainless steel welding wires, significantly increasing operating costs. Furthermore, the drawing process for high-strength welding wires is a crucial factor limiting their development. High-strength welding wires generally exhibit extremely high work hardening characteristics, and large deformation drawing processes cause a rapid increase in wire strength.

[0003] Application No. 201110308343.0, "A High-Strength and Tough All-Austenitic Stainless Steel Welding Wire," incorporates high chromium and high nickel (21-25%), offering advantages such as room-temperature welding and a certain increase in strength. However, the tensile strength of the weld metal after welding only reaches 670-750 MPa, failing to meet welding conditions requiring higher strength. Application No. 201410357157.X, "An Ultra-High-Strength All-Austenitic Stainless Steel Welding Wire," increases wire strength by adding a large amount of carbon. However, the strength of the weld metal in this material only reaches 750 MPa. Furthermore, the high carbon content easily induces granular corrosion, deteriorating the material's corrosion resistance and hindering its use in corrosive environments such as seawater. Application No. 200810228857.3, "An 800MPa Grade High-Strength and High-Toughness Gas-Shielded Welding Wire," can weld base materials with a tensile strength of 800MPa. However, the molten metal requires tempering treatment to increase its tensile strength, and even then, it can only reach 800MPa. Application No. 201210441665.7, "An Ultra-High Strength All-Austenitic Stainless Steel Welding Wire," utilizes nitrogen and high chromium and nickel to improve strength, achieving a tensile strength of up to 790MPa in the deposited metal, with an austenitic microstructure. Application No. 201911202217.X, "A Low-Nickel Nitrogen-Containing Austenitic Stainless Steel Welding Wire and Its Preparation Method," produces a welding wire with stable welding, low porosity, and good welding processability, but the post-weld strength can only reach 820MPa. Application No. 201610185815.0, "A Special Welding Wire for High-Nitrogen Austenitic Stainless Steel," designs a welding wire suitable for welding 1Cr22Mn16N high-nitrogen austenitic stainless steel with a nitrogen content of 0.3-0.6%, which can solve the problem of nitrogen loss during welding of high-nitrogen austenitic stainless steel. However, the strength of the weld metal after welding with this material can only reach 780 MPa, which cannot meet the requirements. Application No. 201510993265.0, "A High-Nitrogen Steel Welding Wire and Its Manufacturing Process," prepares a high-strength, high-toughness welding wire, but the tensile strength of the weld metal can only reach the 750 MPa level, which cannot meet the high-strength requirements. Application No. 201110308343.0, entitled "A High-Strength and Toughness All-Austenitic Stainless Steel Welding Wire," describes the preparation of a high-strength and toughness all-austenitic stainless steel welding wire. This wire enables welding above 0°C without preheating, simplifying the welding process. The weld metal deposited by this wire achieves a maximum strength of 715 MPa, but this still falls short of the 900 MPa level of high strength requirements. Welding materials that simultaneously meet the requirements of high strength, non-magnetic properties, and chloride ion corrosion resistance are not common, and low-cost stainless steel welding wires that meet these requirements are even more difficult to find. Therefore, there is an urgent need to develop a high-strength, non-magnetic, chloride ion corrosion-resistant stainless steel welding wire to overcome this current situation. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a 900MPa-grade non-magnetic, chloride-resistant stainless steel welding wire and its preparation method. The resulting welding wire can be used to weld austenitic materials with a matrix strength >900MPa that are used in chloride ion environments. Furthermore, the weld metal exhibits non-magnetic properties, a tensile strength exceeding 900MPa, and a corrosion rate <0.2g / m² in a 6% FeCl₃ hydrochloric acid solution. 2 *h.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] A 900MPa grade non-magnetic, chloride-resistant stainless steel welding wire has the following chemical composition and mass percentage: C≤0.02%, Si: 0.40~0.50%, Mn: 13~17%, Cr: 18~23%, Ni≤0.3%, Mo: 4.5~6.5%, N: 0.55~0.75%, Cu: 0.20~0.40%, La: 0.02~0.06%, Mg: 0.03~0.06%, P≤100ppm, S≤100ppm, with the balance being Fe and unavoidable impurities.

[0007] Furthermore, the welding wire contains C≤0.01%, Ni≤0.1%, Cu:0.20~0.30%, La:0.02~0.05%, P≤60ppm, and S≤40ppm.

[0008] Furthermore, the welding wire has a diameter of 1.1 to 1.2 mm and a tensile strength of 1650 to 1750 MPa.

[0009] The design basis for the stainless steel welding wire composition of this invention is as follows:

[0010] C: Carbon can improve strength through solid solution strengthening and precipitation strengthening, but it will sacrifice the corrosion resistance of the heat-affected zone through the precipitation of intergranular carbides. Therefore, the addition of carbon should be avoided as much as possible, and the carbon content should be ≤0.01%.

[0011] The addition of silicon can form a protective silicon-rich oxide layer, which is beneficial to the stability of the chromium-rich surface passivation film, improves the corrosion resistance of the material, and increases the welding fluidity of the welding material. However, if there is excessive silicon in the material, it can easily promote the formation of second phases such as carbides and intermetallic compounds. These precipitates are brittle precipitates that accumulate at grain boundaries, deteriorate the plasticity of the material, and are not conducive to processing and forming. At the same time, it can cause chromium depletion at grain boundaries, which can easily induce intergranular corrosion. Therefore, the addition of silicon must be strictly controlled. After analysis and verification, the effect is best when the silicon content is controlled at 0.4-0.5%.

[0012] Mn: Metallic manganese has half the austenite-forming ability of metallic nickel, but it possesses strong austenite stabilizing power. Therefore, it can replace expensive nickel to form stable austenite, ensuring the material's non-magnetic properties. Simultaneously, the addition of manganese significantly increases the solubility of nitrogen in steel, allowing for increased nitrogen content. The addition of manganese also significantly improves material strength. Considering both economic and performance factors, controlling the manganese content at 13-17% yields the best results.

[0013] Cr: Chromium forms an oxide passivation film, which hinders the penetration of corrosion and thus achieves corrosion resistance. To ensure the high corrosion resistance of the deposited metal, the chromium content is controlled at 18-23%.

[0014] Ni: To reduce production costs, nitrogen is used instead of expensive nickel, therefore the nickel content in this application is <0.3%.

[0015] Mo: The addition of molybdenum can significantly improve the corrosion resistance and strength of materials. Taking all factors into consideration, the best effect is achieved by controlling the molybdenum content at 4.5-6.5%.

[0016] Nitrogen (N): As an inexpensive alloying element, nitrogen can improve the stability of austenite by substituting it for nickel. Simultaneously, nitrogen can occupy interstitial positions in the face-centered cubic austenite structure, increasing the material's strength through solid solution strengthening. Studies have shown that for every 0.1% increase in nitrogen, the yield strength of the material increases by approximately 60 MPa. To ensure sufficient strength in the weld metal, the nitrogen content is controlled between 0.55% and 0.75%.

[0017] Cu and Mg: Copper can increase the corrosion resistance of materials, but it weakens the hot workability of materials. Therefore, it is necessary to strictly control the copper content in the material. At the same time, the addition of magnesium can optimize the grain boundary plasticity of the material under high temperature conditions and make up for the weakening effect of copper. Through simulation and experiment, it was determined that the copper content should be controlled at 0.2-0.4% and the magnesium content at 0.03-0.06% so that the material can have both good corrosion resistance and high temperature plasticity.

[0018] La: The addition of rhenium can form high-melting-point oxides with sulfur and oxygen, which are discharged into the slag during the smelting process, thereby achieving the effect of deoxidation and desulfurization. An appropriate amount of rhenium can change the morphology and distribution of carbides, turning large carbides into finely dispersed carbides, modifying other inclusions, and promoting the transformation of polygonal inclusions from aggregated distribution to spherical dispersed distribution. Rhenium is mainly enriched at the grain boundaries, thereby causing carbon to desolvate and diffuse, resulting in a more uniform passivation film on the alloy surface, which is beneficial to the material's resistance to electrochemical corrosion, uniform corrosion, and intergranular corrosion.

[0019] S and P: Sulfur and phosphorus are harmful elements and their addition should be strictly controlled. Therefore, the content of sulfur and phosphorus should be ≤100ppm.

[0020] The production method of the above-mentioned 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire includes non-vacuum induction furnace smelting, electroslag remelting, forging, rolling, solution treatment + pickling, and drawing processes.

[0021] Non-vacuum induction furnace smelting process: melting temperature 1495~1545℃, refining time 45~55min;

[0022] Electroslag remelting process: Electroslag remelting is carried out under a nitrogen protective atmosphere, with the electroslag melting rate controlled at 3.1-3.6 kg / min and the nitrogen flow rate at 20-25 L / min;

[0023] Forging process: Hold at 1120~1150℃ for 4 hours or more, and the deformation amount per forging process is <10mm;

[0024] Rolling process: Hold at 1080~1120℃ for 3 hours or more, roll into φ6mm wire rod, and control the final rolling temperature at 890~910℃;

[0025] Solution treatment and pickling process: The wire rod is solution treated in a tubular annealing furnace at 1060-1080℃ for 30-40 minutes, and then cooled to below 300℃ in water within 30 seconds; pickling is carried out in a sulfuric acid bath with a concentration of 8-10%, with an electrolysis current of 19-22A and a voltage of 13-15V.

[0026] Drawing process: Drawing is carried out at a temperature of 350-400℃. When the diameter is drawn to 3.05-3.15mm and 4.05-4.15mm, two annealing processes are carried out at a temperature of 1060-1080℃.

[0027] The beneficial effects of adopting the above technical solution are as follows: the stainless steel welding wire prepared by this invention has a fully austenitic microstructure in the weld metal after welding, ensuring the non-magnetic nature of the weld metal, while the tensile strength of the weld metal can reach over 900 MPa; in a 6% FeCl3 hydrochloric acid solution, the corrosion rate is less than 0.2 g / m. 2 *h, its resistance to chloride ion corrosion is higher than that of conventional 304 stainless steel. Attached Figure Description

[0028] Figure 1 The images show the morphology of the weld metal sample before and after corrosion of the weld overlay after welding wire was welded onto a 304 stainless steel plate in Example 1. (a) is the morphology before corrosion, and (b) is the morphology after corrosion.

[0029] Figure 2 The images show the morphology of the weld metal sample before and after corrosion of the weld overlay after welding wire was welded onto a 304 stainless steel plate in Example 2. (a) is the morphology before corrosion, and (b) is the morphology after corrosion.

[0030] Figure 3The images show the morphology of the weld metal sample before and after corrosion of the weld overlay after welding wire was welded onto a 304 stainless steel plate in Example 3. (a) is the morphology before corrosion, and (b) is the morphology after corrosion.

[0031] Figure 4 The images show the morphology of the weld metal sample before and after corrosion of the weld overlay after welding wire was welded onto a 304 stainless steel plate in Example 4. (a) is the morphology before corrosion, and (b) is the morphology after corrosion.

[0032] Figure 5 The images show the morphology of the weld metal sample before and after corrosion of the weld overlay after welding wire was welded onto a 304 stainless steel plate in Example 5. (a) is the morphology before corrosion, and (b) is the morphology after corrosion.

[0033] Figure 6 The images show the morphology of the weld metal sample before and after corrosion of the weld overlay after welding wire was welded onto a 304 stainless steel plate in Example 6. (a) is the morphology before corrosion, and (b) is the morphology after corrosion.

[0034] Figure 7 The images show the morphology of the weld metal sample before and after corrosion of the weld overlay after welding wire was welded onto a 304 stainless steel plate in Comparative Example 1. (a) is the morphology before corrosion, and (b) is the morphology after corrosion.

[0035] Figure 8 The images show the morphology of the weld metal sample before and after corrosion of the weld overlay after welding wire was welded onto a 304 stainless steel plate in Comparative Example 2. (a) is the morphology before corrosion, and (b) is the morphology after corrosion.

[0036] Figure 9 The images show the morphology of the weld metal sample before and after corrosion of the weld overlay after welding wire was welded onto a 304 stainless steel plate in Comparative Example 3. (a) is the morphology before corrosion, and (b) is the morphology after corrosion. Implementation

[0037] The present invention will be further described in detail below with reference to the embodiments.

[0038] This invention relates to a 900MPa grade non-magnetic, chloride-resistant stainless steel welding wire with a diameter of 1.1–1.2 mm and a tensile strength of 1650–1750 MPa. Its chemical composition and mass percentage are as follows: C ≤ 0.02%, preferably ≤ 0.01%; Si: 0.40–0.50%; Mn: 13–17%; Cr: 18–23%; Ni ≤ 0.3%, preferably ≤ 0.1%; Mo: 4.5–6.5%; N: 0.55–0.75%; Cu: 0.20–0.40%, preferably 0.20–0.30%; La: 0.02–0.06%, preferably 0.02–0.05%; Mg: 0.03–0.06%; P ≤ 100 ppm, preferably ≤ 60 ppm; S ≤ 100 ppm, preferably ≤ 40 ppm; with the balance being Fe and unavoidable impurities.

[0039] The preparation method of the above-mentioned 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire includes the following process flow: non-vacuum induction furnace smelting, electroslag remelting, forging, rolling, solution treatment + pickling, and drawing.

[0040] Non-vacuum induction furnace smelting process: melting temperature 1495~1545℃, refining time 45~55min;

[0041] Electroslag remelting process: Electroslag remelting is carried out under a nitrogen protective atmosphere, with the electroslag melting rate controlled at 3.1-3.6 kg / min and the nitrogen flow rate at 20-25 L / min;

[0042] Forging process: Hold at 1120~1150℃ for 4 hours or more, and the deformation amount per forging process is <10mm;

[0043] Rolling process: Hold at 1080~1120℃ for 3 hours or more, roll into φ6mm wire rod, and control the final rolling temperature at 890~910℃;

[0044] Solution treatment and pickling process: The wire rod is solution treated in a tubular annealing furnace at 1060-1080℃ for 30-40 minutes, and then cooled to below 300℃ in water within 30 seconds; pickling is carried out in a sulfuric acid bath with a concentration of 8-10%, with an electrolysis current of 19-22A and a voltage of 13-15V.

[0045] Drawing process: Drawing is carried out at a temperature of 350-400℃. When the diameter is drawn to 3.05-3.15mm and 4.05-4.15mm, two annealing processes are carried out at a temperature of 1060-1080℃.

[0046] Specifically, this invention includes 6 sets of examples and 3 sets of comparative examples. The comparative examples adopt the preparation process of this invention to illustrate the product conditions obtained with different components.

[0047] The production process parameters for Examples 1-6 and Comparative Examples 1-3 are shown in Tables 1 and 2, and the chemical composition and mass percentage of the obtained welding wires are shown in Table 3.

[0048] Table 1. Production process parameters for each embodiment and comparative example - 1

[0049]

[0050] Table 2. Production process parameters for each embodiment and comparative example - 2

[0051]

[0052] Table 3. Chemical composition and content (wt%) of welding wires in each embodiment and comparative example

[0053]

[0054] The welding wire materials obtained in the examples and comparative examples were subjected to surfacing experiments on 304 stainless steel plates. The welding process was MAG welding, with a welding current of 195–225 A, a voltage of 235–255 V, and a welding speed of 245–285 mm / min. After each weld was completed and cooled, the weld surface was treated with a stainless steel wire brush to ensure that there was no oxidation or porosity between layers. Tensile specimens were prepared by cutting from the surfacing specimens and tensile tests were conducted using a tensile testing machine. The mechanical properties are shown in Table 4.

[0055] To test the chloride ion corrosion resistance of the welding wire material, 30×30×3mm sample plates were prepared on the weld overlay metal. The surface was ground to ensure uniform surface roughness. The surface was cleaned with alcohol and dried to avoid surface oil stains affecting corrosion performance. The weight W before corrosion was measured. 前 A 6% FeCl3 solution was prepared and placed in a 50°C water bath. The sample was then immersed in the FeCl3 solution for 24 hours. After removal, the surface was ultrasonically treated to remove surface contaminants, cleaned with alcohol, and dried. The weight (W) after corrosion was measured. 后 .

[0056] Corrosion rate = (W) 前 -W 后 ) / S*t

[0057] W 前 ---Sample weight before corrosion test, g;

[0058] W 后 ---Screen weight after corrosion test, in g;

[0059] S---Total area of ​​the sample, m 2 ;

[0060] t---Experiment time, h.

[0061] The corrosion results are shown in Table 4. The morphology of the samples before and after corrosion is shown in the figure. Figure 1-9 .Depend on Figure 1-9 It is known that in a chloride ion corrosive environment, the weld metal deposited by the welding wire of the present invention has excellent corrosion resistance and no corrosion pits caused by corrosion on the surface. In contrast, conventional stainless steel weld metal suffers severe pitting corrosion on the surface under this corrosive environment, resulting in corrosion pits of varying depths.

[0062] Table 4. Specifications and performance of welding wires in each embodiment and comparative example

[0063]

[0064] As can be seen from the tensile test and FeCl3 corrosion test of the weld metal in the examples and comparative examples, the weld metal of the welding wire of the present invention has a much stronger resistance to chloride ion corrosion and tensile strength than conventional stainless steel welding wire, and has excellent mechanical properties and corrosion resistance.

Claims

1. A 900MPa grade non-magnetic stainless steel welding wire resistant to chloride ion corrosion, characterized in that, The chemical composition and mass percentage of the welding wire are as follows: C ≤ 0.02%, Si: 0.40~0.50%, Mn: 13~17%, Cr: 18~23%, Ni ≤ 0.3%, Mo: 4.5~6.5%, N: 0.55~0.75%, Cu: 0.20~0.40%, La: 0.02~0.06%, Mg: 0.03~0.06%, P ≤ 100ppm, S ≤ 100ppm, with the balance being Fe and unavoidable impurities; The preparation method of the welding wire includes non-vacuum induction furnace smelting, electroslag remelting, forging, rolling, solution treatment + pickling, and drawing processes. Non-vacuum induction furnace smelting process: melting temperature 1495~1545℃, refining time 45~55min; Electroslag remelting process: Electroslag remelting is carried out under a nitrogen protective atmosphere, with the electroslag melting rate controlled at 3.1-3.6 kg / min and the nitrogen flow rate at 20-25 L / min; Forging process: Hold at 1120~1150℃ for 4 hours or more, and the deformation amount per forging process is <10mm; Rolling process: Hold at 1080~1120℃ for 3 hours or more, roll into φ6mm wire rod, and control the final rolling temperature at 890~910℃; Solution treatment and pickling process: The wire rod is solution treated in a tubular annealing furnace at 1060-1080℃ for 30-40 minutes. After solution treatment, it is cooled to below 300℃ in water within 30 seconds. After cooling, it is pickled in a sulfuric acid water bath with a concentration of 8-10%. The pickling electrolysis current is 19-22A and the voltage is 13-15V. Drawing process: Drawing is carried out at a temperature of 350-400℃. When the diameter is drawn to 3.05-3.15mm and 4.05-4.15mm, two annealing processes are carried out at a temperature of 1060-1080℃.

2. The 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire according to claim 1, characterized in that, The C≤0.01%, Ni≤0.1%, Cu: 0.20~0.30%, La: 0.02~0.05%, P≤60ppm, S≤40ppm.

3. The 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire according to claim 1 or 2, characterized in that, The diameter of the welding wire is 1.1 to 1.2 mm.

4. A method for preparing 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire according to any one of claims 1-3, characterized in that, It includes non-vacuum induction furnace smelting, electroslag remelting, forging, rolling, solution treatment and pickling, and drawing processes; Solution treatment and pickling process: The wire rod is solution treated in a tubular annealing furnace at 1060-1080℃ for 30-40 minutes, and then cooled and pickled in a sulfuric acid bath with a concentration of 8-10%. Drawing process: Two annealing processes are performed when the diameter is drawn to 3.05-3.15 mm and 4.05-4.15 mm, with an annealing temperature of 1060-1080℃.

5. The method for preparing the 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire according to claim 4, characterized in that, The non-vacuum induction furnace smelting process has a melting temperature of 1495–1545°C and a refining time of 45–55 min.

6. The method for preparing the 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire according to claim 5, characterized in that, The electroslag remelting process is carried out under a nitrogen protective atmosphere, with the electroslag melting rate controlled at 3.1–3.6 kg / min and the nitrogen flow rate at 20–25 L / min.

7. The method for preparing the 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire according to claim 6, characterized in that, The forging process involves holding the temperature at 1120–1150℃ for 4 hours or more, with a single deformation amount of <10mm during the forging process.

8. The method for preparing the 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire according to claim 7, characterized in that, The rolling process involves holding the temperature at 1080–1120℃ for 3 hours or more to roll the wire rod into a φ6mm diameter wire rod, with the final rolling temperature controlled at 890–910℃.

9. The method for preparing the 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire according to claim 8, characterized in that, In the solution treatment and pickling process, the solution is cooled to below 300°C within 30 seconds after solution treatment; the pickling electrolysis current is 19-22A and the voltage is 13-15V.

10. The method for preparing the 900MPa grade non-magnetic chloride ion corrosion resistant stainless steel welding wire according to claim 9, characterized in that, The drawing process is carried out at a temperature of 350–400°C.

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