Corrosion-resistant metal welding material and method of processing the same

Abstract

The present application relates to the technical field of metal welding material, and particularly relates to a kind of corrosion-resistant metal welding material, by the following components consisting of C 0.02%-0.08%, Si 0.15%-0.50%, Mn 0.50%-1.80%, Cr 2.5%-6.0%, Ni 1.5%-4.5%, Mo 0.30%-1.20%, Cu 0.20%-1.00%, Ti 0.01%-0.10%, Nb 0.01%-0.08%, V 0.01%-0.06% by weight percentage;Rare earth elements are selected from one or more of La, Ce, Y, and the content is 0.005%-0.050%;B 0.001%-0.008%, N 0.005%-0.030%, S≤0.005%, P≤0.008%, the balance is Fe and inevitable impurities.The present application significantly improves the pitting corrosion resistance and mechanical properties of weld metal by the composite micro-alloying technology of rare earth and boron under the premise of controllable raw material cost, while ensuring good welding process adaptability, breaking through the limitation of traditional high alloy design, and providing a technical scheme with economic and high performance for steel structure welding in severe corrosive environment such as marine engineering, petrochemical industry and shipbuilding.

Description

Technical Field

[0001] This invention relates to the field of metal welding materials technology, and in particular to a corrosion-resistant metal welding material. Background Technology

[0002] In industries such as marine engineering, petrochemicals, and shipbuilding, critical metal structural components are subjected to prolonged exposure to coupled corrosion environments of high concentrations of chloride ions, acidic media, and high temperature and pressure. As the weakest link in the structure, the corrosion resistance of welded joints directly determines the service life and safety of the equipment. Therefore, developing welding materials that combine excellent pitting corrosion resistance with good weldability has always been a technical challenge in this field.

[0003] In existing technologies, commonly used austenitic stainless steel welding wires, such as ER316L and ER317L, rely on high Cr, Ni, and Mo content to ensure corrosion resistance. However, in Cl... - In environments with concentrations exceeding 2000 ppm or containing H2S, its pitting corrosion resistance remains insufficient, with pitting potentials generally below 350 mV and pitting weight loss rates often exceeding 1.0 mg / cm³. 2 High-nickel alloy welding wires, such as IN625 and Hastelloy C-276, have excellent corrosion resistance, but their nickel content exceeds 50%, resulting in high material costs (approximately 5 to 8 times that of ordinary stainless steel welding wire), which limits their widespread application in large structures.

[0004] Therefore, this invention proposes a corrosion-resistant metal welding material. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a corrosion-resistant metal welding material.

[0006] To achieve the above objectives, the present invention adopts the following technical solution. A corrosion-resistant metal welding material, by weight percentage, comprises the following components: C 0.02%-0.08%, Si 0.15%-0.50%, Mn 0.50%-1.80%, Cr 2.5%-6.0%, Ni 1.5%-4.5%, Mo 0.30%-1.20%, Cu 0.20%-1.00%, Ti 0.01%-0.10%, Nb 0.01%-0.08%, and V 0.01%-0.06%; Rare earth elements are selected from one or more of La, Ce, and Y, with a content of 0.005%-0.050%; B 0.001%-0.008%, N 0.005%-0.030%, S≤ 0.005%, P≤ 0.008%, and the balance is Fe and unavoidable impurities.

[0007] As a preferred technical solution of this application, the total content of the four elements Cr, Ni, Mo and Cu in the corrosion-resistant metal welding material is 5.0%-11.0%.

[0008] As a preferred technical solution of this application, the pitting resistance equivalent PREN value satisfies PREN = Cr% + 3.3×Mo% + 16×N% ≥ 8.0.

[0009] A method for preparing a corrosion-resistant metal welding material includes the following steps: Step S1, Vacuum Melting: Weigh each raw material according to the formula and place them in a vacuum induction melting furnace. Melt the materials under a vacuum of ≤1.0×10⁻⁶. -2 The alloy melt was obtained by melting under Pa conditions at a melting temperature of 1550℃-1650℃ and a holding time of 30-60min. Step S2, Refining and Composition Adjustment: Add refining agent to the alloy melt for refining treatment at a temperature of 1500℃-1580℃ for 20-40 minutes; after refining, take a sample for composition analysis and add the corresponding elements. Step S3, Electroslag Remelting: The refined alloy melt is cast into a consumable electrode and electroslag remelted under a protective atmosphere. The remelting current is 3000-6000A and the remelting voltage is 40-60V to obtain an electroslag ingot. Step S4, Homogenization heat treatment: The electroslag ingot is subjected to homogenization heat treatment at a temperature of 1100℃-1180℃ for 6-12 hours, and then cooled to room temperature with the furnace. Step S5, Forging: Heat the electroslag ingot after homogenization heat treatment to 1100℃-1200℃ and perform multi-pass forging. The final forging temperature is not lower than 900℃. Step S6, Hot rolling: Heat the forging billet to 1050℃-1150℃ and hot roll it into a wire rod with a diameter of 5.5-8.0mm. The final rolling temperature shall not be lower than 850℃. Step S7, Solution treatment: The hot-rolled wire rod is solution treated at 1050℃-1120℃ for 30-90 minutes, and then water-quenched to room temperature. Step S8, Cold drawing: The solution-treated wire rod is subjected to multiple cold drawing processes. The deformation amount of each drawing is 10%-20%, and the total deformation amount is controlled between 60%-85%. Intermediate annealing is carried out during the drawing process at an intermediate annealing temperature of 950℃-1050℃ to obtain the welding wire semi-finished product. Step S9, Final Annealing and Surface Treatment: The cold-drawn welding wire semi-finished product is subjected to final annealing at a temperature of 850℃-950℃ for 10-30 minutes. Then, it is subjected to pickling, water washing, drying and polishing to obtain the finished corrosion-resistant metal welding material.

[0010] As a preferred technical solution of this application, the refining agent in step S2 includes, by weight percentage: CaO 30%-50%, SiO2 20%-35%, Al2O3 10%-20%, MgO 5%-15%, and the amount of refining agent added is 0.5%-2.0% of the total weight of the alloy melt.

[0011] As a preferred technical solution of this application, the slag system of the electroslag remelting in step S3 is as follows by weight percentage: CaF2 55%-65%, Al2O3 15%-25%, CaO 8%-15%, MgO 3%-8%; the protective atmosphere is argon or nitrogen.

[0012] Application of a corrosion-resistant metal welding material in metal structure welding in marine engineering, petrochemical or shipbuilding fields.

[0013] The beneficial effects of this invention are as follows: 1. By using rare earth elements and boron in a composite microalloying process, the localized corrosion resistance of weld metal in a chloride ion environment is significantly improved. During the metallurgical process, rare earth elements preferentially combine with oxygen and sulfur in the molten steel to form fine, high-melting-point inclusions, reducing the damage to the passivation film integrity caused by large non-metallic inclusions. Simultaneously, the enrichment of rare earth elements on the passivation film surface effectively inhibits the selective penetration of chloride ions. Boron, by refining the grain structure and improving grain boundary bonding, makes the passivation film more uniform and dense, and provides faster self-repair capability after localized damage. The synergistic effect of these two elements makes the pitting corrosion resistance of the welding material of this invention significantly superior to traditional methods that rely solely on chromium, molybdenum, and nitrogen content optimization, providing more reliable localized corrosion protection under the same PREN conditions. 2. The addition of rare earth elements promotes the formation ratio of isometric crystals in the weld solidification structure, refines the grain size, and thus produces a significant fine-grain strengthening effect. Simultaneously, fine grains facilitate coordinated deformation, thereby simultaneously improving the material's plasticity reserve. With appropriate addition of boron, part of it dissolves in the matrix to produce solid solution strengthening, while the other part forms fine, dispersed second-phase particles with carbon and nitrogen, playing a precipitation strengthening role. By controlling the boron content within a reasonable range, grain boundary brittleness is avoided. Under the combined effect, the tensile strength and yield strength of the welding material of this invention are both at a high level, while maintaining good elongation after fracture, achieving a good match between strength and plasticity, and meeting the structural design requirements for strict load-bearing capacity and deformation capacity of welded joints. 3. During welding, the electric arc burns stably, the molten droplets transfer evenly, and spatter is minimal. The slag coverage is complete and has good peelability from the weld metal, making post-weld cleaning simple. The weld formation is aesthetically pleasing, with a smooth surface and free from common welding defects such as porosity, cracks, and undercut. This is attributed to the improvement of steel purity by rare earth elements, which reduces the content of dissolved gases and inclusions in the weld, thereby reducing the porosity rate; the effective inhibition of crystallization crack sensitivity by boron elements also ensures the integrity of the weld during solidification. These process characteristics make the material of this invention suitable for automated and semi-automated welding scenarios, with a high tolerance for operating parameters, which is beneficial for ensuring the stability of welding quality under actual engineering conditions. 4. By controlling the nickel content at a low level, the dependence on expensive nickel resources is significantly reduced. Unlike high-nickel alloy welding wire, which requires a large amount of nickel-based raw materials, this invention uses iron-based materials as the main component, with performance enhanced by the addition of trace amounts of rare earth elements and boron. Under the same corrosion resistance and mechanical property requirements, the raw material cost of this invention is significantly lower than that of high-nickel alloy welding wire, giving it a good economic advantage and making it suitable for promotion in large-scale engineering applications.

[0014] In summary, this invention, through the composite microalloying technology of rare earth and boron, significantly improves the pitting corrosion resistance and mechanical properties of weld metal under the premise of controllable raw material costs, while ensuring good welding process adaptability. It breaks through the limitations of traditional high alloying design and provides a technical solution that balances economy and high performance for steel structure welding in harsh corrosive environments such as marine engineering, petrochemicals, and shipbuilding. Detailed Implementation

[0015] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0016] I. Experimental Design The experimental methods, equipment, standards, etc. used for the metal welding materials prepared in the examples and comparative examples are referenced in the table below.

[0017]

[0018] II. Specific details of the embodiments and comparative examples Example 1

[0019] A corrosion-resistant metal welding material, by weight percentage, comprises the following components: C 0.03%, Si 0.20%, Mn 0.80%, Cr 4.8%, Ni 2.0%, Mo 1.0%, Cu 0.30%, Ti 0.03%, Nb 0.02%, and V 0.02%; The rare earth element is La, with a content of 0.008%; B 0.002%, N 0.025%, S 0.003%, P 0.005%, with the balance being Fe and unavoidable impurities.

[0020] The method for preparing the corrosion-resistant metal welding material described in this embodiment includes the following steps: Step S1, Vacuum Melting: Weigh each raw material according to the formula and place them in a vacuum induction melting furnace. Melt the materials under a vacuum of ≤1.0×10⁻⁶. -2 The alloy melt was obtained by melting under Pa conditions at a melting temperature of 1600℃ and a holding time of 45min. Step S2, Refining and Composition Adjustment: A refining agent is added to the alloy melt for refining at 1550℃ for 30 minutes. After refining, a sample is taken for composition analysis, and the corresponding elements are added. The refining agent, by weight percentage, includes: CaO 40%, SiO2 25%, Al2O3 18%, MgO 10%, with the balance being unavoidable impurities. The amount added is 1.2% of the total melt weight. Step S3, Electroslag Remelting: The refined alloy melt is cast into a consumable electrode and electroslag remelted under a protective atmosphere. The remelting current is 4000A and the remelting voltage is 50V to obtain an electroslag ingot. The slag system of the electroslag remelting is as follows by weight percentage: CaF2 60%, Al2O3 20%, CaO 12%, MgO 5%, with the balance being unavoidable impurities. Step S4, Homogenization heat treatment: The electroslag ingot is subjected to homogenization heat treatment at 1150℃ for 8 hours, and then cooled to room temperature with the furnace. Step S5, Forging: Heat the electroslag ingot after homogenization heat treatment to 1150℃ and perform multi-pass forging to open the billet. The final forging temperature is 950℃. Step S6, Hot rolling: Heat the forging billet to 1100℃ and hot roll it into a wire rod with a diameter of 6.0mm. The final rolling temperature is 900℃. Step S7, Solution treatment: The hot-rolled wire rod is solution treated at 1100℃ for 60 minutes, and then water quenched to room temperature. Step S8, Cold drawing: The solution-treated wire rod is subjected to multiple cold drawing processes. The deformation amount of each drawing is 15%, and the total deformation amount is controlled at 70%. Intermediate annealing is carried out in the middle of the drawing process at a temperature of 1000℃ to obtain the welding wire semi-finished product. Step S9, Final Annealing and Surface Treatment: The cold-drawn welding wire semi-finished product is subjected to final annealing at 900℃ for 20 minutes. Then, it is pickled with 15% sulfuric acid solution at 65℃ for 20 minutes. After that, it is washed with water, dried and polished to obtain the corrosion-resistant metal welding material finished product.

[0021] Example 2

[0022] A corrosion-resistant metal welding material, by weight percentage, comprises the following components: C 0.05%, Si 0.35%, Mn 1.20%, Cr 5.2%, Ni 3.0%, Mo 0.85%, Cu 0.50%, Ti 0.05%, Nb 0.04%, and V 0.03%; The rare earth element is Ce, with a content of 0.025%; B 0.005%, N 0.020%, S 0.002%, P 0.006%, with the balance being Fe and unavoidable impurities.

[0023] The method for preparing the corrosion-resistant metal welding material described in this embodiment includes the following steps: Step S1, Vacuum Melting: Weigh each raw material according to the formula and place them in a vacuum induction melting furnace. Melt the materials under a vacuum of ≤1.0×10⁻⁶. -2 The alloy melt was obtained by melting under Pa conditions at a melting temperature of 1600℃ and a holding time of 45min. Step S2, Refining and Composition Adjustment: A refining agent is added to the alloy melt for refining at 1550℃ for 30 minutes. After refining, a sample is taken for composition analysis, and the corresponding elements are added. The refining agent, by weight percentage, includes: CaO 40%, SiO2 25%, Al2O3 18%, MgO 10%, with the balance being unavoidable impurities. The amount added is 1.2% of the total melt weight. Step S3, Electroslag Remelting: The refined alloy melt is cast into a consumable electrode and electroslag remelted under a protective atmosphere. The remelting current is 4000A and the remelting voltage is 50V to obtain an electroslag ingot. The slag system of the electroslag remelting is as follows by weight percentage: CaF2 60%, Al2O3 20%, CaO 12%, MgO 5%, with the balance being unavoidable impurities. Step S4, Homogenization heat treatment: The electroslag ingot is subjected to homogenization heat treatment at 1150℃ for 8 hours, and then cooled to room temperature with the furnace. Step S5, Forging: Heat the electroslag ingot after homogenization heat treatment to 1150℃ and perform multi-pass forging to open the billet. The final forging temperature is 950℃. Step S6, Hot rolling: Heat the forging billet to 1100℃ and hot roll it into a wire rod with a diameter of 6.0mm. The final rolling temperature is 900℃. Step S7, Solution treatment: The hot-rolled wire rod is solution treated at 1100℃ for 60 minutes, and then water quenched to room temperature. Step S8, Cold drawing: The solution-treated wire rod is subjected to multiple cold drawing processes. The deformation amount of each drawing is 15%, and the total deformation amount is controlled at 70%. Intermediate annealing is carried out in the middle of the drawing process at a temperature of 1000℃ to obtain the welding wire semi-finished product. Step S9, Final Annealing and Surface Treatment: The cold-drawn welding wire semi-finished product is subjected to final annealing at 900℃ for 20 minutes. Then, it is pickled with 15% sulfuric acid solution at 65℃ for 20 minutes. After that, it is washed with water, dried and polished to obtain the corrosion-resistant metal welding material finished product.

[0024] Example 3

[0025] A corrosion-resistant metal welding material, by weight percentage, comprises the following components: C 0.07%, Si 0.45%, Mn 1.50%, Cr 5.8%, Ni 4.0%, Mo 0.70%, Cu 0.80%, Ti 0.08%, Nb 0.06%, and V 0.05%; The rare earth element is Y, with a content of 0.040%; B 0.007%, N 0.015%, S 0.004%, P 0.004%, with the balance being Fe and unavoidable impurities.

[0026] The method for preparing the corrosion-resistant metal welding material described in this embodiment includes the following steps: Step S1, Vacuum Melting: Weigh each raw material according to the formula and place them in a vacuum induction melting furnace. Melt the materials under a vacuum of ≤1.0×10⁻⁶. -2 The alloy melt was obtained by melting under Pa conditions at a melting temperature of 1600℃ and a holding time of 45min. Step S2, Refining and Composition Adjustment: A refining agent is added to the alloy melt for refining at 1550℃ for 30 minutes. After refining, a sample is taken for composition analysis, and the corresponding elements are added. The refining agent, by weight percentage, includes: CaO 40%, SiO2 25%, Al2O3 18%, MgO 10%, with the balance being unavoidable impurities. The amount added is 1.2% of the total melt weight. Step S3, Electroslag Remelting: The refined alloy melt is cast into a consumable electrode and electroslag remelted under a protective atmosphere. The remelting current is 4000A and the remelting voltage is 50V to obtain an electroslag ingot. The slag system of the electroslag remelting is as follows by weight percentage: CaF2 60%, Al2O3 20%, CaO 12%, MgO 5%, with the balance being unavoidable impurities. Step S4, Homogenization heat treatment: The electroslag ingot is subjected to homogenization heat treatment at 1150℃ for 8 hours, and then cooled to room temperature with the furnace. Step S5, Forging: Heat the electroslag ingot after homogenization heat treatment to 1150℃ and perform multi-pass forging to open the billet. The final forging temperature is 950℃. Step S6, Hot rolling: Heat the forging billet to 1100℃ and hot roll it into a wire rod with a diameter of 6.0mm. The final rolling temperature is 900℃. Step S7, Solution treatment: The hot-rolled wire rod is solution treated at 1100℃ for 60 minutes, and then water quenched to room temperature. Step S8, Cold drawing: The solution-treated wire rod is subjected to multiple cold drawing processes. The deformation amount of each drawing is 15%, and the total deformation amount is controlled at 70%. Intermediate annealing is carried out in the middle of the drawing process at a temperature of 1000℃ to obtain the welding wire semi-finished product. Step S9, Final Annealing and Surface Treatment: The cold-drawn welding wire semi-finished product is subjected to final annealing at 900℃ for 20 minutes. Then, it is pickled with 15% sulfuric acid solution at 65℃ for 20 minutes. After that, it is washed with water, dried and polished to obtain the corrosion-resistant metal welding material finished product.

[0027] Comparative Example 1 A corrosion-resistant metal welding material, by weight percentage, comprises the following components: C 0.04%, Si 0.25%, Mn 1.00%, Cr 5.0%, Ni 2.5%, Mo 0.90%, Cu 0.40%, Ti 0.04%, Nb 0.03%, and V 0.02%; B 0.003%, N 0.018%, S 0.003%, P 0.005%, balance Fe and unavoidable impurities.

[0028] The preparation method of the corrosion-resistant metal welding material described in the comparative example includes the following steps: Step S1, Vacuum Melting: Weigh each raw material according to the formula and place them in a vacuum induction melting furnace. Melt the materials under a vacuum of ≤1.0×10⁻⁶. -2 The alloy melt was obtained by melting under Pa conditions at a melting temperature of 1600℃ and a holding time of 45min. Step S2, Refining and Composition Adjustment: A refining agent is added to the alloy melt for refining at 1550℃ for 30 minutes. After refining, a sample is taken for composition analysis, and the corresponding elements are added. The refining agent, by weight percentage, includes: CaO 40%, SiO2 25%, Al2O3 18%, MgO 10%, with the balance being unavoidable impurities. The amount added is 1.2% of the total melt weight. Step S3, Electroslag Remelting: The refined alloy melt is cast into a consumable electrode and electroslag remelted under a protective atmosphere. The remelting current is 4000A and the remelting voltage is 50V to obtain an electroslag ingot. The slag system of the electroslag remelting is as follows by weight percentage: CaF2 60%, Al2O3 20%, CaO 12%, MgO 5%, with the balance being unavoidable impurities. Step S4, Homogenization heat treatment: The electroslag ingot is subjected to homogenization heat treatment at 1150℃ for 8 hours, and then cooled to room temperature with the furnace. Step S5, Forging: Heat the electroslag ingot after homogenization heat treatment to 1150℃ and perform multi-pass forging to open the billet. The final forging temperature is 950℃. Step S6, Hot rolling: Heat the forging billet to 1100℃ and hot roll it into a wire rod with a diameter of 6.0mm. The final rolling temperature is 900℃. Step S7, Solution treatment: The hot-rolled wire rod is solution treated at 1100℃ for 60 minutes, and then water quenched to room temperature. Step S8, Cold drawing: The solution-treated wire rod is subjected to multiple cold drawing processes. The deformation amount of each drawing is 15%, and the total deformation amount is controlled at 70%. Intermediate annealing is carried out in the middle of the drawing process at a temperature of 1000℃ to obtain the welding wire semi-finished product. Step S9, Final Annealing and Surface Treatment: The cold-drawn welding wire semi-finished product is subjected to final annealing at 900℃ for 20 minutes. Then, it is pickled with 15% sulfuric acid solution at 65℃ for 20 minutes. After that, it is washed with water, dried and polished to obtain the corrosion-resistant metal welding material finished product.

[0029] Comparative Example 2 A corrosion-resistant metal welding material, by weight percentage, comprises the following components: C 0.06%, Si 0.40%, Mn 1.30%, Cr 5.0%, Ni 3.5%, Mo 0.90%, Cu 0.70%, Ti 0.06%, Nb 0.05%, and V 0.04%; The rare earth element is La, with a content of 0.008%; N 0.022%, S 0.004%, P 0.007%, and the balance is Fe and unavoidable impurities.

[0030] The preparation method of the corrosion-resistant metal welding material described in the comparative example includes the following steps: Step S1, Vacuum Melting: Weigh each raw material according to the formula and place them in a vacuum induction melting furnace. Melt the materials under a vacuum of ≤1.0×10⁻⁶. -2 The alloy melt was obtained by melting under Pa conditions at a melting temperature of 1600℃ and a holding time of 45min. Step S2, Refining and Composition Adjustment: A refining agent is added to the alloy melt for refining at 1550℃ for 30 minutes. After refining, a sample is taken for composition analysis, and the corresponding elements are added. The refining agent, by weight percentage, includes: CaO 40%, SiO2 25%, Al2O3 18%, MgO 10%, with the balance being unavoidable impurities. The amount added is 1.2% of the total melt weight. Step S3, Electroslag Remelting: The refined alloy melt is cast into a consumable electrode and electroslag remelted under a protective atmosphere. The remelting current is 4000A and the remelting voltage is 50V to obtain an electroslag ingot. The slag system of the electroslag remelting is as follows by weight percentage: CaF2 60%, Al2O3 20%, CaO 12%, MgO 5%, with the balance being unavoidable impurities. Step S4, Homogenization heat treatment: The electroslag ingot is subjected to homogenization heat treatment at 1150℃ for 8 hours, and then cooled to room temperature with the furnace. Step S5, Forging: Heat the electroslag ingot after homogenization heat treatment to 1150℃ and perform multi-pass forging to open the billet. The final forging temperature is 950℃. Step S6, Hot rolling: Heat the forging billet to 1100℃ and hot roll it into a wire rod with a diameter of 6.0mm. The final rolling temperature is 900℃. Step S7, Solution treatment: The hot-rolled wire rod is solution treated at 1100℃ for 60 minutes, and then water quenched to room temperature. Step S8, Cold drawing: The solution-treated wire rod is subjected to multiple cold drawing processes. The deformation amount of each drawing is 15%, and the total deformation amount is controlled at 70%. Intermediate annealing is carried out in the middle of the drawing process at a temperature of 1000℃ to obtain the welding wire semi-finished product. Step S9, Final Annealing and Surface Treatment: The cold-drawn welding wire semi-finished product is subjected to final annealing at 900℃ for 20 minutes. Then, it is pickled with 15% sulfuric acid solution at 65℃ for 20 minutes. After that, it is washed with water, dried and polished to obtain the corrosion-resistant metal welding material finished product.

[0031] III. Experimental Results and Analysis 1. Pitting performance Table 1 Comparison of pitting corrosion performance

[0032] Analysis of Table 1 shows that, in terms of pitting potential, all three examples (1-3) reached over 490 mV, with Example 1 having the highest (510 mV), indicating that its passivation film exhibited the strongest breakdown resistance under chloride ion conditions. In contrast, Comparative Example 1 (without rare earth elements) and Comparative Example 2 (without boron) had pitting potentials of only 310 mV and 330 mV, respectively, a decrease of approximately 180-160 mV compared to Example 2 (which had the most similar composition, with a PREN value of 8.3), representing a reduction of nearly 40%. This indicates that under the same PREN value, the addition of rare earth elements and boron has a significant impact on pitting resistance.

[0033] The weight loss rate in all three sets of examples was less than 0.12 mg / cm³. 2 The lowest concentration was observed in Example 1 (0.08 mg / cm³). 2 This indicates that the surface passivation film repairs extremely quickly, and localized corrosion is effectively suppressed. In contrast, the weight loss rates of comparative examples 1 and 2 were as high as 1.28 mg / cm³. 2 and 1.05 mg / cm 2 The value is more than 10 times that of the example, indicating that without the addition of rare earth or boron, once the passivation film is locally damaged, it is difficult to repair itself quickly, eventually leading to the expansion of severe pitting corrosion.

[0034] The PREN value only reflects the theoretical contribution of Cr, Mo, and N elements to the stability of the passivation film, but the actual corrosion resistance also depends on the film's density, uniformity, and self-healing ability. Rare earth elements (La, Ce, Y) have strong chemical reactivity and can form stable high-melting-point rare earth oxides / sulfides with impurities such as oxygen and sulfur in molten steel during high-temperature smelting, reducing the number of inclusions and making them finely dispersed, thus improving the continuity of the passivation film. Simultaneously, after rare earth elements accumulate on the surface of the passivation film, they can increase the film's ion diffusion resistance and inhibit Cl... - Penetration.

[0035] The role of boron is mainly reflected in two aspects: First, boron segregates at grain boundaries, which can improve grain boundary bonding and reduce intergranular corrosion susceptibility. Secondly, boron reacts with carbon and nitrogen to form fine boron carbonitrides, which serve as heterogeneous nucleation sites, promoting the refinement of the weld solidification structure and thus forming a more uniform and dense passivation film.

[0036] In addition, boron can reduce the hot cracking tendency of weld metal and reduce the formation of microcracks, which are often the preferred sites for pitting corrosion.

[0037] Therefore, the comparison between Example 2 (containing rare earth and boron) and Comparative Example 1 (without rare earth) and Comparative Example 2 (without boron) clearly illustrates that the PREN value alone cannot predict the true pitting corrosion resistance. The synergistic effect of rare earth and boron is the key to achieving high corrosion resistance in this invention.

[0038] 2. Mechanical properties of weld Table 2 Comparison of mechanical properties of welds

[0039] Analysis of Table 2 shows that the tensile strength of all three examples is above 620 MPa, with Example 3 having the highest (655 MPa) and a yield strength of 475 MPa, while maintaining an elongation at break above 25% (good plasticity). Comparative Examples 1 and 2 have tensile strengths of only 580 MPa and 590 MPa, respectively, and their yield strengths are also significantly lower, with a difference of approximately 30-50 MPa. More notably, in terms of elongation at break, Example 1 reaches 28%, while Comparative Example 1 is only 22%, a difference of 6 percentage points, indicating that the plasticity reserve of the examples is significantly better than that of the comparative examples. Hardness data also supports this trend: the hardness of the examples is approximately 230-255 HV10, while the comparative examples are only 215-220 HV10.

[0040] These differences in mechanical properties mainly stem from variations in microstructure. Rare earth elements, as surface-active elements, can reduce the liquid-solid interface energy during solidification, decreasing dendrite spacing and promoting the formation of equiaxed crystals while inhibiting excessive columnar crystal growth. The refined grains result in a grain-refining strengthening effect, and the increased grain boundary area facilitates coordinated deformation, thus simultaneously improving both strength and plasticity. The role of boron is equally significant: boron can dissolve in the matrix, producing a certain degree of solid solution strengthening, and boron forms fine, dispersed precipitates with carbon and nitrogen (such as Fe). 23 (C,B)6, BN, etc.) can hinder dislocation movement and improve strength; however, excessive boron can lead to grain boundary brittleness (such as the formation of low-melting-point eutectic). This invention controls boron in the range of 0.001%-0.008%, which just balances the relationship between strengthening and toughness.

[0041] Comparative Example 1 (without rare earth elements) has a relatively coarse microstructure with more and unevenly sized intragranular inclusions, leading to an increase in stress concentration points and ultimately a decrease in both strength and plasticity. Comparative Example 2 (without boron) has weak solid solution strengthening and lacks the grain boundary purification effect of boron, making the grain boundaries more prone to premature cracking during tensile testing, thus resulting in a more significant decrease in plasticity.

[0042] The side bending test results were all qualified (d=4a, 120°), indicating that the bending plasticity of all specimens met the engineering requirements and no fracture occurred. However, the bending deformation of the embodiment was more uniform (by observing the bent surface without specific data), further proving that it had better microstructure uniformity and toughness reserve.

[0043] Table 3 Welding process adaptability evaluation

[0044] Analysis of Table 3 shows that the example exhibits a stable arc, minimal spatter, complete slag coverage, and excellent slag removal during welding, resulting in a smooth and aesthetically pleasing weld surface. Comparative Example 2 (boron-free) shows occasional micropores during welding, which is related to the reduced gas escape channels during steel solidification due to boron deficiency. Comparative Example 1 (rare earth-free) shows no obvious pores but slightly more spatter. This indicates that rare earth and boron not only synergistically enhance the final performance but also play positive roles in the welding process, such as stabilizing the arc, purifying the molten steel, and suppressing porosity.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A corrosion-resistant metal welding material, characterized in that, By weight percentage, it consists of the following components: C 0.02%-0.08%, Si 0.15%-0.50%, Mn 0.50%-1.80%, Cr 2.5%-6.0%, Ni 1.5%-4.5%, Mo 0.30%-1.20%, Cu 0.20%-1.00%, Ti 0.01%-0.10%, Nb 0.01%-0.08%, and V 0.01%-0.06%. Rare earth elements are selected from one or more of La, Ce, and Y, with a content of 0.005%-0.050%; B 0.001%-0.008%, N 0.005%-0.030%, S ≤ 0.005%, P ≤ 0.008%, and the balance is Fe and unavoidable impurities.

2. The corrosion-resistant metal welding material according to claim 1, characterized in that, The total content of the four elements Cr, Ni, Mo and Cu in the corrosion-resistant metal welding material is 5.0%-11.0%.

3. The corrosion-resistant metal welding material according to claim 1, characterized in that, The pitting resistance equivalent PREN value satisfies PREN = Cr% + 3.3×Mo% + 16×N% ≥ 8.

0.

4. A method for preparing a corrosion-resistant metal welding material according to any one of claims 1-3, characterized in that, Includes the following steps Step S1, Vacuum Melting: Weigh each raw material according to the formula and place them in a vacuum induction melting furnace. Melt the materials under a vacuum of ≤1.0×10⁻⁶. - 2 The alloy melt was obtained by melting under Pa conditions at a melting temperature of 1550℃-1650℃ and a holding time of 30-60min. Step S2, Refining and Composition Adjustment: Add refining agent to the alloy melt for refining treatment at a temperature of 1500℃-1580℃ for 20-40 minutes; after refining, take a sample for composition analysis and add the corresponding elements. Step S3, Electroslag Remelting: The refined alloy melt is cast into a consumable electrode and electroslag remelted under a protective atmosphere. The remelting current is 3000-6000A and the remelting voltage is 40-60V to obtain an electroslag ingot. Step S4, Homogenization heat treatment: The electroslag ingot is subjected to homogenization heat treatment at a temperature of 1100℃-1180℃ for 6-12 hours, and then cooled to room temperature with the furnace. Step S5, Forging: Heat the electroslag ingot after homogenization heat treatment to 1100℃-1200℃ and perform multi-pass forging. The final forging temperature is not lower than 900℃. Step S6, Hot rolling: Heat the forging billet to 1050℃-1150℃ and hot roll it into a wire rod with a diameter of 5.5-8.0mm. The final rolling temperature shall not be lower than 850℃. Step S7, Solution treatment: The hot-rolled wire rod is solution treated at 1050℃-1120℃ for 30-90 minutes, and then water-quenched to room temperature. Step S8, Cold drawing: The solution-treated wire rod is subjected to multiple cold drawing processes. The deformation amount of each drawing is 10%-20%, and the total deformation amount is controlled between 60%-85%. Intermediate annealing is carried out during the drawing process at an intermediate annealing temperature of 950℃-1050℃ to obtain the welding wire semi-finished product. Step S9, Final Annealing and Surface Treatment: The cold-drawn welding wire semi-finished product is subjected to final annealing at a temperature of 850℃-950℃ for 10-30 minutes. Then, it is subjected to pickling, water washing, drying and polishing to obtain the finished corrosion-resistant metal welding material.

5. The method for preparing a corrosion-resistant metal welding material according to claim 4, characterized in that, The refining agent mentioned in step S2 includes, by weight percentage: CaO 30%-50%, SiO2 20%-35%, Al2O3 10%-20%, MgO 5%-15%, and the amount of refining agent added is 0.5%-2.0% of the total weight of the alloy melt.

6. The method for preparing a corrosion-resistant metal welding material according to claim 4, characterized in that, The slag system of the electroslag remelting in step S3 is as follows by weight percentage: CaF2 55%-65%, Al2O3 15%-25%, CaO 8%-15%, MgO 3%-8%; the protective atmosphere is argon or nitrogen.

7. The application of the corrosion-resistant metal welding material according to claims 1-3 or the corrosion-resistant metal welding material prepared by any one of claims 4-6 in the field of marine engineering, petrochemical or shipbuilding welding.

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