High-corrosion-resistance carbon-free Cr-Ni-Mo solid welding wire and preparation method thereof

Abstract

This invention relates to the field of welding materials technology, and particularly to a high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire and its preparation method. The high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire uses Fe as the matrix, with a carbon content ≤0.001%. The specific alloy element composition by mass percentage is: C ≤0.001%, Mn: 0.3%-0.8%, Si: 0.1%-0.4%, Cr: 8.0%-10.0%, Mo: 3.2%-4.0%, Ni: 12.0%-13.5%, Nb: 0.1%-0.3%, Ti: 0.05%-0.15%, with the balance being Fe and impurities. The preparation method includes: S100, vacuum induction melting; S200, AOD decarburization refining; S300, multi-pass hot rolling of wire rod; S400, multi-pass cold drawing; S500, vacuum annealing; and S600, finishing and polishing. A high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire has the advantages of ultra-high strength and toughness, safe and controllable operation under extreme working conditions, excellent dimensional stability, strong corrosion resistance, excellent welding processability, and wide range of applications, which helps to promote the localization of high-end equipment.

Description

Technical Field

[0001] This invention relates to the field of welding materials technology, and in particular to a high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire and its preparation method. Background Technology

[0002] In recent years, my country's deep-sea manned, exploration, and polar test platforms have been developing rapidly. Because their structures must withstand extreme conditions such as high hydrostatic pressure, seawater corrosion, extremely low temperatures, and frictional wear for extended periods, the requirements for material performance are extremely high. However, for welded steel structures, performance can only be controlled through composition and welding processes, and internal quality cannot be improved through forging or rolling, making the weld seam a weak point. To ensure the safe operation of the equipment, welding materials with compositions matching the base metal are crucial. Considering the compatibility of welding wire strength with the base metal, there is an urgent need to develop a high-purity, carbon-free Cr-Ni-Mo solid welding wire. This avoids the easy formation of M6C and M23C6 type carbides by carbon with alloying elements such as chromium, molybdenum, and vanadium, which can cause a series of problems such as intergranular corrosion in the joint fusion zone, poor low-temperature toughness, high-temperature embrittlement, and large weld deformation.

[0003] Traditional carbon-containing or low-carbon ferroalloy welding wires generally have a carbon content higher than 0.03%, which cannot meet the stringent quality requirements of weld materials for equipment used in extreme environments. To improve the performance of welding wires, various research institutions have achieved significant results. For example, Chinese invention patent CN116606980A discloses a method for preparing high-quality H08A welding steel wire rod billets. This method includes steel smelting, deoxidation and alloying, LF furnace refining, and continuous casting. By optimizing the parameters of each process step, this invention significantly improves the castability of H08A steel, enabling incremental production of H08A steel billets in single-ladle castings and achieving a breakthrough in the number of continuous casting furnaces per ladle, thus possessing the capability for mass production of high-quality H08A welding steel wire rod billets. However, the welding wires disclosed in this patent are not completely carbon-free, cannot completely avoid carbide precipitation, have limited weld purity and dimensional stability, and lack strength and toughness. Furthermore, the alloy ratio is not optimized for carbon-free systems and does not rely on alloys such as nickel, molybdenum, and chromium to achieve carbon-free strengthening. Summary of the Invention

[0004] In view of this, the present invention aims to provide a high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire, which adopts the core technology advantage of carbon strengthening, uses Fe as the matrix, and has a carbon content of ≤0.001%, which is far lower than the carbon content standard of ≤0.03% for conventional carbon-free steel. It solves the problems of not achieving complete carbon-free, being unable to completely avoid carbide precipitation, having limited weld purity and dimensional stability, insufficient strength and toughness, and the alloy ratio not being optimized for carbon-free systems, and not relying on alloys such as nickel, molybdenum, and chromium to achieve carbon-free strengthening.

[0005] To address the aforementioned problems, this invention provides a high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire, with Fe as the base material and a carbon content ≤0.001%. The specific alloy element composition by mass percentage is: C≤0.001%, Mn: 0.3%-0.8%, Si: 0.1%-0.4%, Cr: 8.0%-10.0%, Mo: 3.2%-4.0%, Ni: 12.0%-13.5%, Nb: 0.1%-0.3%, Ti: 0.05%-0.15%, with the balance being Fe and impurities.

[0006] Furthermore, the diameter of the welding wire is 1.0mm-2.0mm.

[0007] Furthermore, the weld metal yield strength is ≥620MPa, tensile strength is ≥680MPa, and low-temperature impact energy at -60℃ is ≥145J.

[0008] Furthermore, it is suitable for welding special steel structures and precision parts in extreme environments where the carbon content of the weld seam is strictly controlled, and the weld has high purity, high toughness, excellent corrosion resistance, and dimensional stability.

[0009] Furthermore, the weld microstructure is martensite + austenite, and the butt joint is free from pitting corrosion, crevice corrosion, and stress corrosion.

[0010] A method for preparing a high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire, used to prepare the high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire as described in any of the preceding claims, the method comprising:

[0011] S100, vacuum induction melting;

[0012] S200, AOD decarbonization refining;

[0013] S300, multi-pass hot-rolled wire rod;

[0014] S400, multi-pass cold drawing;

[0015] S500, vacuum annealing;

[0016] S600, fine finishing and polishing;

[0017] The entire process uses carbon-free refractory material corundum-spinel bricks.

[0018] Furthermore, in step S100, the vacuum induction melting method includes:

[0019] The raw materials selected are pig iron, metallic chromium, metallic manganese, ferromolybdenum, metallic niobium, sponge titanium, and pure iron. The purity of all raw materials is ≥99.9%, and the content of S and P impurities is ≤0.005%.

[0020] The raw materials were ultrasonically cleaned three times with anhydrous ethanol and dried at 120℃ for 2 hours.

[0021] The vacuum induction melting furnace uses a carbon-free crucible with a vacuum degree ≤2Pa and a melting temperature of 1550-1620℃.

[0022] The order of feeding is pig iron → Mn → Si → Cr → Mo → Ni → Nb → Ti;

[0023] After adding Ti, stir with pure argon for 2 minutes, and the furnace temperature is 1600±20℃.

[0024] Furthermore, in step S200, the method for AOD decarbonization and refining includes:

[0025] Oxidation and decarburization period, reduction and refining period, purification and homogenization period;

[0026] During the oxidative decarbonization period, the O2:Ar ratio is 3:1, the gas supply intensity is 0.8-1.2 m³ / (t・min), and the temperature is 1580-1630℃.

[0027] During the reduction and refining process, pure argon stirring is used, and carbon-free silicon manganese and carbon-free aluminum particles are added for deep deoxidation and desulfurization.

[0028] During the purification and temperature equalization period, pure argon bottom blowing is performed for 15-20 minutes, with an endpoint temperature of 1610-1640℃.

[0029] Endpoint control: C ≤ 0.001%, O ≤ 20 ppm, S ≤ 0.005%, P ≤ 0.008%;

[0030] The oxygen content in the casting chamber is ≤50ppm. Carbon-free nozzles and carbon-free mold linings are used for slow and steady flow casting. Carbon-free protective slag is added to the top, and demolding is carried out below 300℃.

[0031] Furthermore, in step S300, the method for multi-pass hot rolling of wire rod includes:

[0032] Homogenized steel ingots are heated to 1200-1250℃, held for 2-3 hours, and then hot-rolled in 5-6 passes to produce Φ10.0mm welding wire rods;

[0033] The initial rolling temperature is 1180-1200℃, and the final rolling temperature is ≥850℃.

[0034] Furthermore, in step S400, the multi-pass cold drawing method includes:

[0035] The staged diameter reduction uses carbon-free lubrication, with a single-pass deformation of 8-12% and a total deformation rate of 85%-92%.

[0036] The welding wire has a dimensional accuracy of ±0.01mm and a surface free of scratches and burrs.

[0037] Compared with existing technologies, the high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire of the present invention has the following advantages:

[0038] The advantage of this technical solution lies in its use of carbon-strengthened core technology. With Fe as the matrix and a carbon content ≤0.001%, far lower than the conventional carbon-free steel standard of ≤0.03%, it offers the following advantages:

[0039] (1) Ultra-high strength and toughness, safe and controllable under extreme working conditions: The carbon-free weld has a uniform structure and extremely fine grains. Relying on the synergistic strengthening of nickel-molybdenum alloy, the weld metal yield strength is ≥620MPa, tensile strength is ≥680MPa, and low-temperature impact energy at -60℃ is ≥145J.

[0040] (2) Extreme dimensional stability: The carbon-free microstructure combined with the alloy stabilization design results in a low coefficient of thermal expansion of the weld. After high-temperature aging treatment, the weld deformation under temperature fluctuations is extremely small, far lower than that of traditional welding wire welds.

[0041] (3) Super corrosion resistance: The carbon-free design combined with the synergistic support of nickel, chromium and molybdenum alloys gives the weld excellent corrosion resistance. The anti-rust time in salt spray environment is far longer than that of conventional welding materials, and it can be used in deep sea and polar environments.

[0042] (4) Excellent welding process: solid welding wire structure, smooth wire feeding, no segregation, small welding spatter, and beautiful weld formation.

[0043] (5) Wide range of applications, helping the localization of high-end equipment: Breaking through the limitations of traditional low-carbon welding wire applications, it is an important welding material for the localization of high-end equipment and the upgrading of precision manufacturing. Attached Figure Description

[0044] Figure 1 The image shows the metallographic structure of the weld after welding with the welding wire described in the embodiments of this application. Detailed Implementation

[0045] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0046] In this invention, the terms "first," "second," "upper," and "lower," etc., are used for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," "upper," or "lower" may explicitly or implicitly include at least one of those features. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. Where the technical solutions of the embodiments can be combined, they are all within the scope of protection claimed by this invention.

[0047] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] like Figure 1 As shown, a high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire is produced. The welding wire adopts the core technology advantage of carbon-free strengthening, with Fe as the matrix and a carbon content of ≤0.001%, which is far lower than the standard of ≤0.03% carbon content for conventional carbon-free steel. The specific alloy element composition by mass percentage is: C≤0.001%, Mn: 0.3%-0.8%, Si: 0.1%-0.4%, Cr: 8.0%-10.0%, Mo: 3.2%-4.0%, Ni: 12.0%-13.5%, Nb: 0.1%-0.3%, Ti: 0.05%-0.15%, with the balance being Fe and unavoidable trace impurities. Welding wire preparation process: High-purity carbon-free pig iron + pure alloy powder vacuum melting → AOD refining → hot rolling blanking → multi-pass cold drawing → vacuum annealing → fine finishing and polishing. Carbon-free refractory materials (corundum-spinel bricks) are used throughout the process, and the carbon element infiltration is strictly controlled to finally produce solid carbon-free iron alloy welding wire with a diameter of 1.0mm-2.0mm.

[0049] The welding wire breaks through the conventional limit of carbon content in welding wires, achieving carbon-free (C≤0.001%) and completely eliminating the hidden danger of carbide precipitation; relying on alloys such as nickel, molybdenum, and chromium to achieve carbon-free solid solution strengthening, solving the problem of strength and toughness imbalance in carbon-free systems, and its performance is comparable to the strengthening logic of 18Ni200 martensitic aging steel, filling the gap in domestic high-end welding materials technology for carbon-free ferroalloys; adopting a full-process carbon-free pure preparation process, controlling carbon penetration and steel contamination throughout the process.

[0050] The specific chemical composition and the reasons for the limitations are shown in Table 1:

[0051] Table 1

[0052]

[0053] Furthermore, the weld metal yield strength is ≥620MPa, tensile strength is ≥680MPa, and low-temperature impact energy at -60℃ is ≥145J.

[0054] A method for preparing a high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire, used to prepare the high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire as described above. The welding wire is prepared using a process of "vacuum induction melting + AOD refining + hot rolling + cold drawing", the specific process of which is as follows:

[0055] S100, vacuum induction melting;

[0056] ① The raw materials selected are high-purity pig iron (C≤0.0005%), high-purity metallic chromium, metallic manganese, ferromolybdenum, metallic niobium, high-purity sponge titanium, and low-carbon pure iron. The purity of all raw materials is ≥99.9%, and the content of S and P impurities is ≤0.005%.

[0057] ②The raw materials are ultrasonically cleaned three times with anhydrous ethanol and dried at 120℃ for 2 hours;

[0058] ③ Smelting is carried out in a vacuum induction furnace. The crucible must be a carbon-free crucible with a vacuum degree ≤2Pa. The smelting temperature is 1550-1620℃. The order of adding materials is: high-purity pig iron → Mn → Si → Cr → Mo → Ni → Nb → Ti. After adding Ti, stir with pure argon for 2 minutes. The furnace outlet temperature is 1600±20℃.

[0059] S200, AOD decarbonization refining;

[0060] Oxidation and decarburization period: O2:Ar=3:1, gas supply intensity 0.8-1.2m³ / (t•min), 1580-1630℃; Reduction and refining period: pure argon stirring, deep deoxidation and desulfurization of carbon-free silicon manganese and carbon-free aluminum particles; Purification and temperature equalization period: pure argon bottom blowing for 15-20min, final temperature 1610-1640℃; Final control: C≤0.001%, O≤20ppm, S≤0.005%, P≤0.008%; Oxygen content in the casting chamber ≤50ppm, carbon-free nozzle, carbon-free mold lining; slow and steady flow casting, carbon-free protective slag added to the top, demolding below 300℃.

[0061] S300, multi-pass hot-rolled wire rod;

[0062] Hot rolling process: Homogenized steel ingots are heated to 1200-1250℃, held for 2-3 hours, and then hot rolled in 5-6 passes to produce Φ10.0mm welding wire rods; initial rolling temperature 1180-1200℃, final rolling temperature ≥850℃.

[0063] S400, multi-pass cold drawing;

[0064] The process involves progressive diameter reduction with carbon-free lubrication, resulting in a single-pass deformation of 8-12% and a total deformation rate of 85%-92%. The dimensional accuracy is ±0.01mm, and the surface is free of scratches and burrs.

[0065] S500, vacuum annealing;

[0066] S600, fine polishing.

[0067] Furthermore, it is suitable for welding special steel structures and precision parts in extreme environments where the carbon content of the weld seam is strictly controlled, and the weld has high purity, high toughness, excellent corrosion resistance, and dimensional stability.

[0068] Furthermore, the weld microstructure is martensite + austenite, and the butt joint is free from pitting corrosion, crevice corrosion, and stress corrosion.

[0069] The present invention will be further described below with reference to specific embodiments.

[0070] The welding wires of Examples 1-4 were trial-produced using the composition and preparation process of this invention. The chemical composition and preparation process are shown in Tables 2 and 3, respectively. Under laboratory conditions, the trial-produced welding wires were successfully welded, and the joint performance is shown in Table 4. The results show that the tensile strength of the joints is higher than 700 MPa, the yield strength is higher than 600 MPa, the impact energy at -60℃ is not less than 100 J, and the butt joints are free from pitting corrosion, crevice corrosion, and stress corrosion.

[0071] Table 2 (Unit: %)

[0072]

[0073] Table 3

[0074]

[0075] The welding wire properties obtained by combining the components and preparation processes of the above embodiments are shown in Table 4.

[0076] Table 4

[0077]

[0078] As can be seen from the above specific embodiments, by using the components of this application and the preparation process of this application, and leveraging the core advantages of carbon strengthening technology, with Fe as the matrix and a carbon content ≤0.001%, which is far lower than the conventional carbon-free steel standard of ≤0.03%, the obtained welding wire achieves the following advantages:

[0079] (1) Ultra-high strength and toughness, safe and controllable under extreme working conditions: The carbon-free weld has a uniform structure and extremely fine grains. Relying on the synergistic strengthening of nickel-molybdenum alloy, the weld metal yield strength is ≥620MPa, tensile strength is ≥680MPa, and low-temperature impact energy at -60℃ is ≥145J.

[0080] (2) Extreme dimensional stability: The carbon-free microstructure combined with the alloy stabilization design results in a low coefficient of thermal expansion of the weld. After high-temperature aging treatment, the weld deformation under temperature fluctuations is extremely small, far lower than that of traditional welding wire welds.

[0081] (3) Super corrosion resistance: The carbon-free design combined with the synergistic support of nickel, chromium and molybdenum alloys gives the weld excellent corrosion resistance. The anti-rust time in salt spray environment is far longer than that of conventional welding materials, and it can be used in deep sea and polar environments.

[0082] (4) Excellent welding process: solid welding wire structure, smooth wire feeding, no segregation, small welding spatter, and beautiful weld formation.

[0083] (5) Wide range of applications, helping the localization of high-end equipment: Breaking through the limitations of traditional low-carbon welding wire applications, it is an important welding material for the localization of high-end equipment and the upgrading of precision manufacturing.

[0084] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire, characterized in that, With Fe as the matrix and a carbon content ≤0.001%, the specific alloy element composition by mass percentage is: C≤0.001%, Mn: 0.3%-0.8%, Si: 0.1%-0.4%, Cr: 8.0%-10.0%, Mo: 3.2%-4.0%, Ni: 12.0%-13.5%, Nb: 0.1%-0.3%, Ti: 0.05%-0.15%, with the balance being Fe and impurities. The weld metal has a yield strength ≥620MPa, a tensile strength ≥680MPa, and a low-temperature impact energy of -60℃ ≥145J. The weld microstructure is martensite + austenite, and the butt joint is free from pitting corrosion, crevice corrosion, and stress corrosion.

2. The high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire according to claim 1, characterized in that, The diameter of the welding wire is 1.0mm-2.0mm.

3. The high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire according to claim 1, characterized in that, Suitable for welding special steel structures and precision parts in extreme environments where strict control of weld carbon content, high purity, high toughness, excellent corrosion resistance, and dimensional stability are required.

4. A method for preparing a high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire, used to prepare the high corrosion-resistant carbon-free Cr-Ni-Mo solid welding wire as described in any one of claims 1-3, characterized in that, The preparation method includes: S100, vacuum induction melting; S200, AOD decarbonization refining; S300, multi-pass hot-rolled wire rod; S400, multi-pass cold drawing; S500, vacuum annealing; S600, fine finishing and polishing; The entire process uses carbon-free refractory material corundum-spinel bricks.

5. The preparation method according to claim 4, characterized in that, In step S100, the vacuum induction melting method includes: The raw materials selected are pig iron, metallic chromium, metallic manganese, ferromolybdenum, metallic niobium, sponge titanium, and pure iron. The purity of all raw materials is ≥99.9%, and the content of S and P impurities is ≤0.005%. The raw materials were ultrasonically cleaned three times with anhydrous ethanol and dried at 120℃ for 2 hours. The vacuum induction melting furnace uses a carbon-free crucible with a vacuum degree ≤2Pa and a melting temperature of 1550-1620℃. The order of feeding is pig iron → Mn → Si → Cr → Mo → Ni → Nb → Ti; After adding Ti, stir with pure argon for 2 minutes, and the furnace temperature is 1600±20℃.

6. The preparation method according to claim 4, characterized in that, In step S200, the method for AOD decarbonization and refining includes: Oxidation and decarburization period, reduction and refining period, purification and homogenization period; During the oxidative decarbonization period, the O2:Ar ratio is 3:1, the gas supply intensity is 0.8-1.2 m³ / (tmin), and the temperature is 1580-1630℃. During the reduction and refining process, pure argon stirring is used, and carbon-free silicon manganese and carbon-free aluminum particles are added for deep deoxidation and desulfurization. During the purification and temperature equalization period, pure argon bottom blowing is performed for 15-20 minutes, with an endpoint temperature of 1610-1640℃. Endpoint control: C ≤ 0.001%, O ≤ 20 ppm, S ≤ 0.005%, P ≤ 0.008%; The oxygen content in the casting chamber is ≤50ppm. Carbon-free nozzles and carbon-free mold linings are used for slow and steady flow casting. Carbon-free protective slag is added to the top, and demolding is carried out below 300℃.

7. The preparation method according to claim 4, characterized in that, In step S300, the method for multi-pass hot rolling of wire rod includes: Homogenized steel ingots are heated to 1200-1250℃, held for 2-3 hours, and then hot-rolled in 5-6 passes to produce Φ10.0mm welding wire rods; The initial rolling temperature is 1180-1200℃, and the final rolling temperature is ≥850℃.

8. The preparation method according to claim 4, characterized in that, In step S400, the method for multi-pass cold drawing includes: The staged diameter reduction uses carbon-free lubrication, with a single-pass deformation of 8-12% and a total deformation rate of 85%-92%. The welding wire has a dimensional accuracy of ±0.01mm and a surface free of scratches and burrs.

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