Method for preparing ODS steel welding wire based on spray deposition and electric arc melting combined technology

Abstract

The invention belongs to the field of welding wire preparation, and particularly relates to a method for preparing an ODS steel welding wire based on a spray deposition and electric arc melting combined process. According to the technical scheme, the preparation method comprises the following steps: performing surface modification on Y2O3 particles and Fe powder to prepare mixed powder; an ODS alloy is smelted through a closed double-cabin smelting-injection system; during spray deposition, the preheated mixed powder is loaded; performing electric arc melting to form a nano oxide dispersed phase and strictly controlling the oxygen content of the ingot blank; the ingot blank is subjected to temperature equalization before forging, and H2 / Ar mixed gas is introduced; high-temperature rough rolling and low-temperature finish rolling are adopted for hot rolling strengthening; carrying out solid solution and two-stage aging composite heat treatment; hot drawing wire forming is matched with gradient annealing and protective atmosphere; and carrying out surface treatment through pulse copper electroplating or anti-oxidation layer spraying. According to the method, alloy components and microstructures can be accurately regulated and controlled, the problems of strengthening phase distribution and machining defects can be efficiently solved, and the strict requirements for high performance and high reliability of ODS steel welding wires in the fields of nuclear reactors, aerospace and the like are met.

Description

Technical Field

[0001] The present invention belongs to the field of welding wire preparation, and in particular relates to a method for preparing ODS steel welding wire based on a spray deposition coordinated arc melting composite process. Background Art

[0002] In modern industry, especially in high-end industries such as nuclear reactors and aerospace, the performance requirements for materials are extremely stringent. High-performance, high-reliability welding materials have become a core element in ensuring the quality and safe operation of key components. ODS steel, with its outstanding high-temperature strength, creep resistance, and good oxidation resistance, exhibits unique advantages in these high-temperature, high-stress environments, and its demand as a welding material is increasing. However, traditional ODS steel welding wire preparation technology faces many challenges. Conventional smelting methods make it difficult to accurately control the alloy composition, resulting in deviations in the proportions of key elements such as Cr, W, Ti, and Y in ODS steel, affecting its ultimate performance. At the same time, when introducing strengthening phases such as Y2O3, traditional processes cannot effectively achieve uniform distribution and interface bonding of particles, and agglomeration and segregation are prone to occur, greatly weakening the strength and toughness of the material. In addition, during subsequent processing, such as drawing and rolling, internal defects in the material are difficult to eliminate, further limiting the promotion of ODS steel welding wire in high-end application scenarios.

[0003] Patent CN 118664175 A discloses a high-strength steel welding wire and its preparation method. This method utilizes an optimized raw material ratio (e.g., 0.07-0.075% carbon powder and 0.043-0.068% halloysite nanotubes) combined with conventional vacuum melting, rolling, and rust prevention processes to produce a low-spatter, low-cost high-strength steel welding wire. While this method reduces precious metal usage by adjusting the alloying element ratio, it lacks nano-oxide dispersion strengthening technology, spray deposition, arc melting, or gradient thermal processing, resulting in insufficient high-temperature creep resistance and insufficient uniformity of the strengthening phase distribution.

[0004] Patent CN 118559281 A discloses an austenitic stainless steel welding wire and its preparation method. Its characteristics are that it utilizes a chemical composition design with high Mn (16.1% to 25.9%) and ultra-low impurities (P+S+O ≤ 0.015%), combined with vacuum induction melting, electroslag remelting, forging, hot rolling, and solution treatment to produce a high-strength and toughness welding wire suitable for extreme low-temperature environments such as 4.2K liquid nitrogen. While this method significantly improves low-temperature performance through composition optimization and conventional processing, it does not involve nano-oxide dispersion strengthening technology, nor does it employ spray deposition, arc melting composite processes, or gradient thermal processing, and therefore cannot address the issues of high-temperature creep resistance and uniform distribution of strengthening phases. Summary of the Invention

[0005] The present invention provides a method for preparing ODS steel welding wire based on a spray deposition coordinated arc melting composite process. The mass fraction of Y2O3 in the welding wire is 0.05-1%, the particle size is 5-50nm, and the wire is evenly distributed; the yield strength is ≥850MPa, the tensile strength is ≥1200MPa, the elongation at room temperature is ≥20%, and the high temperature (800℃) creep resistance is improved by ≥40%; the weld strength and matrix matching degree is ≥95%, and the spatter rate is ≤3%; the alloy composition and microstructure can be precisely controlled, and the problems of strengthening phase distribution and processing defects can be efficiently solved, so as to meet the strict requirements of nuclear reactors, aerospace and other fields for high performance and high reliability of ODS steel welding wire.

[0006] The technical solutions of the present invention are as follows:

[0007] The method for preparing ODS steel welding wire based on a spray deposition synergistic arc melting composite process comprises the following steps:

[0008] 1) Surface modification of Y2O3 particles: ball milling Y2O3 particles and Fe powder in liquid nitrogen or alcohol for 24 to 48 hours at a rotation speed of 450 to 700 r / min and a ball-to-material ratio of 5:1 to 10:1; Fe powder particle size of 20 to 30 μm; Y2O3 mass fraction ≥ 90%; surface metal coating thickness of 0.1 to 0.5 μm; to form a mixed powder of Y2O3 particles and Fe;

[0009] 2) Closed dual-chamber melting-injection system for melting ODS alloys: The melting chamber and the spray deposition chamber are isolated by a gate valve. The vacuum degree of the melting chamber is ≤5×10-2Pa. The spray deposition chamber is equipped with a high-speed vacuum pump to maintain the ambient pressure ≤5000Pa. Vacuum medium-frequency induction is used in the melting chamber to melt the ODS alloy. The ODS alloy composition is: Cr 8-18%, C 0.1-1%, W 0.5-5%, Ti 0.1-2%, Y 0.05-2%, Si 0.05-1%, and the balance is Fe. The melting capacity is 1-5t.

[0010] 3) Spray deposition and powder feeding: The superheat of the ODS molten steel is controlled at +50-200°C, and after deslagging and degassing with bottom argon blowing, it is injected into a tundish preheated to ≥1200°C; the mixed powder is preheated to ≥600°C and loaded into the spray deposition area through gas-solid two-phase flow. The mixed powder is embedded in the deposition ingot, and the interface is well bonded;

[0011] 4) Arc Melting: The deposited ingot is arc melted 1 to 3 times at a melting current of 1000 to 3500 A, with Ar as the shielding gas, and the oxygen content of the ingot after melting is ≤50 ppm; Y2O3 particles are partially dissolved during the arc melting to form a nano-oxide dispersed phase with a size of 5 to 50 nm and a volume fraction of 0.05 to 1%;

[0012] 5) Ingot pretreatment and forging: The ingot is heated to 800°C at a rate of ≤80°C / h and held for 1 hour to eliminate residual stress; the ingot is further heated to a target temperature of 1180-1250°C at a rate of ≤50°C / h, and then the ingot is stretched and forged into a cube along the height direction; during the holding stage, a H2 / Ar mixed gas is introduced, wherein the H2 accounts for 5-8%, the flow rate is 10-20 L / min, and the hydrogen partial pressure is controlled at 0.05-0.15 atm to promote Y2O3 surface activation;

[0013] 6) Hot rolling: The cube is subjected to a two-stage process of "high-temperature rough rolling + low-temperature finishing rolling", with a rough rolling temperature of 1150-1200°C to complete 70% deformation and a finishing rolling temperature of 900-850°C to complete the remaining deformation; the hot rolling thickness is 3-15mm to obtain a plate;

[0014] 7) Composite heat treatment: The plate is first solution treated at 1050-1150°C for 30-60 minutes, and then rapidly cooled to room temperature to retain the supersaturated solid solution; then subjected to two-stage aging treatment: medium-temperature aging at 750-800°C for 4-8 hours and low-temperature stabilization at 550-600°C for 12-24 hours, so that the size of the precipitated phase is stabilized at 5-50 nm;

[0015] 8) Hot drawing: After composite heat treatment, the plate is continuously drawn by multi-mode for 12-24 times, using carbide dies ±0.01mm, with nano-graphite lubrication, temperature 80-120℃; gradient annealing: 800-1000℃×30-60s, H2 / N2 anti-oxidation; cumulative deformation ≥85% is formed <110> Texture, strength ≥ 5MRD, Y-Ti-O phase stable at 5-50nm; steel wire obtained;

[0016] 9) Surface treatment: The steel wire is subjected to pulse copper electroplating with a controlled current density of 3-5A / dm 2 , coating 1-5μm, surface roughness Ra≤0.8μm, coating conductivity ≥80% IACS; or spray Al2O3 / SiO2-TiO2 composite anti-oxidation layer.

[0017] Furthermore, in the method for preparing ODS steel welding wire based on the spray deposition coordinated arc melting composite process, in the step 1), the volume of liquid nitrogen in the ball milling tank is filled with 60-90% of the tank volume to ensure that the powder is completely immersed in the low-temperature environment; the ball milling is repeated for 24-48 hours in a mode of ball milling for 2-4 hours and standing for 20-60 minutes, and the liquid nitrogen is completely volatilized to form a dry Fe powder-coated Y2O3 mixed powder.

[0018] Furthermore, in the method for preparing ODS steel welding wire based on the spray deposition coordinated arc melting composite process, in the step 1), the mass ratio of alcohol to the mixed powder is 1:1 to 3:1, and the volume of alcohol accounts for 30 to 50%; the ball milling is repeated for 24 to 48 hours in a mode of ball milling time of 2 to 4 hours and standing for 20 to 60 minutes; the alcohol evaporates naturally to a residual amount of ≤0.5wt%.

[0019] Furthermore, in the method for preparing ODS steel welding wire based on the spray deposition coordinated arc melting composite process, in the step 3), double nozzles are horizontally arranged at the bottom of the ladle, the single nozzle flow rate is 20 to 60 kg / min, the nozzle outlet flow rate is 1.0 to 2.0 m / min, and the outer nozzle aperture area is 15 to 25% larger than the inner nozzle.

[0020] Furthermore, in the method for preparing ODS steel welding wire based on the spray deposition coordinated arc melting composite process, in the step 4), the melting voltage is 20-50V, and the volume fraction of the shielding gas Ar is 95%-99%.

[0021] Furthermore, in the method for preparing ODS steel welding wire based on the spray deposition synergistic arc melting composite process, in the step 5), the deformation amount per pass during forging is 15-25%, and the strain rate is 0.5-2s -1 .

[0022] Furthermore, in the method for preparing ODS steel welding wire based on the spray deposition coordinated arc melting composite process, in the step 6), the grain size is refined to 20-50 μm after rough rolling, and the dynamic recrystallization rate is ≥80%; the final rolling temperature control deviation is ≤±10°C, and the austenite is rolled in the non-recrystallized zone, and the grains are further refined to 5-15 μm; the surface oxide layer thickness is ≤10 μm, and no additional pickling is required to meet the subsequent drawing requirements.

[0023] Furthermore, in the method for preparing ODS steel welding wire based on the spray deposition coordinated arc melting composite process, in step 7), the step cooling rate during the two-stage aging treatment is ≤20°C / h.

[0024] Furthermore, in the method for preparing ODS steel welding wire based on the spray deposition synergistic arc melting composite process, in the step 8), the gradient annealing temperature is increased in three stages from 800°C to 950°C to 1000°C, the single stage holding time is 30-60s, and a mixed protective atmosphere of H2 / N2=1:3 volume ratio is used throughout the process; <110> The axial preferred orientation texture and the phase spacing of the Y-Ti-O precipitated phase are maintained at 100-200nm.

[0025] Furthermore, in the method for preparing ODS steel welding wire based on the spray deposition synergistic arc melting composite process, in the step 9), the thickness of the Al2O3 / SiO2-TiO2 composite anti-oxidation layer is 8-15 μm, and the weight gain per unit area after the 800°C oxidation test is ≤2 mg / cm 2 ; Implement thermal shock cycle ( The spatter rate of the treated layer is ≤2.5% and there is no peeling defect.

[0026] The design principle of the present invention is: the present invention aims to solve the problems of uneven distribution of nano-oxides, weak interface bonding and insufficient high-temperature performance in traditional ODS steel welding wires by innovatively integrating spray deposition and arc melting technology. The core of the design revolves around four major technical paths: First, liquid nitrogen or alcohol medium ball milling is used to modify the surface of Y2O3 particles, and the wettability with molten steel is significantly improved by Fe powder coating (thickness 0.1-0.5μm), combined with low temperature environment or alcohol volatilization control, to ensure that the mixed powder is dry without residue, laying the foundation for uniform dispersion for subsequent processes; secondly, a vacuum double-chamber melting-spraying system is constructed, and a melting chamber (vacuum degree ≤5×10-2Pa) is used to achieve high-purity ODS steel liquid melting, and the modified mixed powder is embedded in the deposited ingot through dual-nozzle jet deposition (single nozzle flow rate 20-60kg / min) at the same time, and the arc gas is used to maintain melting. The instantaneous high temperature and dynamic stirring of the refining (current 1000-3500A) promote the partial dissolution of Y2O3 and the in-situ generation of nano-oxide dispersed phase (5-50nm), while suppressing the oxygen content to ≤50ppm; thirdly, the microstructure and properties are optimized through precision hot processing and gradient heat treatment, including H2 / Ar activation temperature (hydrogen partial pressure 0.05-0.15atm), two-stage rolling (rough rolling 1150-1200℃ / finishing rolling 900-850℃) to refine the grains to 5-15μm, and solid solution-aging composite heat treatment to stabilize the precipitated phase (5-50nm), combined with multi-pass hot drawing (cumulative deformation ≥85%) to form <110> texture, ensuring that the Y-Ti-O phase is stably distributed in 5-50nm; finally, by pulse electroplating copper (conductivity ≥ 80% IACS) or Al2O3 / SiO2-TiO2 composite coating (800℃ weight gain ≤ 2mg / cm 2 ) to achieve surface functionalization, and after thermal shock and bending verification (spatter rate ≤ 2.5%), the final welding wire is obtained with a yield strength ≥ 850MPa, a tensile strength ≥ 1200MPa, and a high-temperature creep resistance improvement of ≥ 40%. The weld strength and matrix matching degree are ≥ 95%, which meets the high-precision welding requirements in extreme environments of nuclear reactors and aerospace, and provides a systematic solution for the industrial preparation of high-performance ODS steel welding wire.

[0027] The beneficial effects of the present invention are:

[0028] 1. The present invention achieves uniform distribution and interface strengthening of nano-oxide dispersed phase (5-50nm) through surface-modified Y2O3 particles and a double-chamber melting-spray deposition collaborative process. In the preparation of traditional ODS steel welding wire, Y2O3 particles are easy to agglomerate and have poor wettability with the matrix, resulting in weak interface bonding and insufficient mechanical properties. The present invention uses liquid nitrogen or alcohol ball milling to coat the Fe layer (thickness 0.1-0.5μm), combined with spray deposition gas-solid two-phase flow synchronous powder feeding (preheating ≥600℃), so that the Y2O3 particles are embedded in the steel liquid matrix and form a dense interface. The final Y2O3 particle size in the welding wire is 5-50nm, the volume fraction is 0.05-1%, the yield strength is ≥850MPa, and the tensile strength is ≥1200MPa, which is 30%-40% higher than the traditional process.

[0029] 2. The present invention significantly reduces the oxygen content of the ingot to ≤50ppm and inhibits the formation of impurity phases through a vacuum dual-chamber melting system (melting chamber ≤5×10-2Pa, injection chamber ≤5000Pa) and arc gas shielded melting (current 1000-3500A, Ar protection). Traditional arc melting of ODS steel results in an increase in oxide inclusions due to insufficient vacuum (usually >0.1Pa), affecting high-temperature creep performance. The present invention uses dual-chamber isolation and high-purity Ar protection, combined with dynamic stirring, to promote the partial dissolution of Y2O3, forming an in-situ nano-dispersed phase (volume fraction 0.05-1%), and improving creep resistance at 800°C by ≥40%, far exceeding traditional welding wire (improvement ≤20%).

[0030] 3. The present invention uses a gradient thermal processing process (rough rolling 1150-1200°C + finishing rolling 900-850°C) and a composite heat treatment (solution + two-stage aging) to prepare the ODS steel ingots produced by the spray deposition and arc melting composite process, thereby achieving grain refinement (5-15μm) and precipitation phase stabilization (5-50nm). The traditional ODS steel rolling process is single, the grain size is mostly >50μm, and the precipitation phase is coarsened (>100nm). The present invention adopts two-stage rolling (cumulative deformation ≥85%) combined with step aging (750-800°C × 4-8h + 550-600°C × 12-24h), the dynamic recrystallization rate is ≥80%, the grain boundary segregation is reduced by 70%, and the room temperature elongation is ≥20%, which is 50% higher than the conventional process.

[0031] 4. The ODS steel ingot prepared by the spray deposition synergistic arc melting composite process of the present invention adopts multi-pass hot drawing (12 to 24 passes) and gradient annealing (800 to 1000 ° C) to form a strong <110> Texture (strength ≥ 5MRD) and stable Y-Ti-O phase (5-50nm). Traditional drawing processes have low cumulative deformation (≤ 60%) and weak texture strength (≤ 3MRD), resulting in significant anisotropy in the wire. The present invention uses cemented carbide dies (tolerance ± 0.01mm) and nanographite lubrication (80-120°C) to control total deformation ≥ 85%, phase spacing 100-200nm, spatter rate ≤ 2.5%, and weld matching ≥ 95%, surpassing the industry standard (spatter rate > 5%).

[0032] 5. The present invention significantly improves the oxidation resistance and conductivity of ODS steel welding wire prepared by spray deposition and arc melting composite process through surface functionalization treatment (pulse electroplating copper or Al2O3 / SiO2-TiO2 coating). Conventional welding wire has rough coating (Ra>1.5μm), low conductivity (<70% IACS), and high temperature oxidation weight gain>5mg / cm 2 (800℃). The present invention adopts pulse plating (3~5A / dm 2 ) to obtain ultra-thin copper layer (1-5μm, Ra≤0.8μm, conductivity ≥80% IACS), or spray composite coating (8-15μm, 800℃ weight gain ≤2mg / cm 2 ), thermal shock cycle There is no peeling in the bending test (≥50 times), and the storage period is extended to 24 months, meeting the extreme environmental requirements of nuclear reactors and aerospace. DETAILED DESCRIPTION

[0033] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] Example 1

[0035] A method for preparing ODS steel welding wire based on a spray deposition-coordinated arc melting composite process, which optimizes conductivity and welding stability through liquid nitrogen ball milling, single arc melting, and pulse copper plating. The method includes the following steps:

[0036] 1) Surface modification of Y2O3 particles:

[0037] Y2O3 powder with a particle size of 25 μm was mixed with Fe powder (particle size of 20-30 μm) in a mass ratio of 9:1 and ball milled in a liquid argon immersion environment. The ball milling jar was made of cemented carbide, the ball-to-material ratio was 8:1, and the ball milling speed was 550 r / min for 36 hours. After ball milling, a 0.3 μm Fe metal coating layer was formed on the surface of the Y2O3, and the coating rate was ≥95%.

[0038] 2) Double vacuum chamber closed melting:

[0039] The vacuum degree of the melting chamber is set at 3×10-2Pa, and the pressure of the jet deposition chamber is maintained at 3000Pa by a high-speed vacuum pump. A vacuum medium-frequency induction furnace is used in the melting chamber to melt the ODS alloy with the following composition: Cr 12%, C 0.5%, W 2.5%, Ti0.8%, Y 0.3%, Si 0.3%, and the balance is Fe. The total melting volume is 2.5 tons.

[0040] 3) Spray deposition and powder feeding:

[0041] The superheat of the ODS steel liquid is controlled at +120°C, and after deslagging and degassing with bottom-blown argon (flow rate 15L / min), it is injected into a tundish preheated to 1250°C; the bottom of the tundish adopts a double-nozzle design, with the outer nozzle aperture 18% larger than the inner one, a single nozzle flow rate of 40kg / min, and a nozzle outlet flow rate of 1.5m / min; the Y2O3 / Fe mixed powder is preheated to 650°C, delivered into the deposition area by an argon carrier flow (flow rate 8m / s), and embedded in the interior of the deposition ingot, with an interface bonding strength ≥200MPa.

[0042] 4) Arc gas shielded consumable melting:

[0043] The deposited ingot was subjected to single arc melting with a melting current of 2500A, a voltage of 35V, and a shielding gas of 99.5% high-purity argon. After melting, the ingot had an oxygen content of 35ppm, and the Y2O3 particles were partially dissolved to form a 35nm Y-Ti-O nano-dispersed phase with a volume fraction of 0.3%.

[0044] 5) Ingot pretreatment and forging:

[0045] The temperature was raised to 800°C at 60°C / h and kept at this temperature for 1 hour to eliminate residual stress; the temperature was further raised to 1200°C at 40°C / h; H2 / Ar mixed gas (H2 accounted for 6%, flow rate 15L / min, hydrogen partial pressure 0.1atm) was introduced during the holding period; the forging process was performed along the height direction, with a deformation of 20% per pass and a strain rate of 1.2s -1 , the grain size after forging is 45μm.

[0046] 6) Precision hot rolling process enhancement:

[0047] Rough rolling stage: temperature 1180℃, rolling speed 0.8m / s, 75% deformation, dynamic recrystallization rate 85%; finishing rolling stage: temperature 880℃, rolling speed 0.5m / s, surface oxide layer thickness 7μm, grain refinement to 12μm.

[0048] 7) Composite heat treatment after hot rolling:

[0049] Solution treatment: 1100℃×45min, water cooling rate 50℃ / s, to obtain a supersaturated solid solution; two-stage aging: medium temperature aging: 780℃×6h, precipitate phase size 30nm; low temperature stabilization: 580℃×18h (cooling rate 15℃ / h), precipitate phase spacing 120nm.

[0050] 8) Hot drawing into wire:

[0051] 18-pass continuous drawing was adopted, with a carbide die tolerance of ±0.01mm and a deformation of 8% to 12% per pass; the nanographite lubricant temperature was 100°C, and the gradient annealing process was: 800°C × 40s → 900°C × 50s → 1000°C × 30s, in an H2 / N2 protective atmosphere (volume ratio 1:3); the cumulative deformation was 88%, forming a strong <110> Axial texture (polar density 5.2MRD), the Y-Ti-O phase size is stable at 50nm.

[0052] 9) Surface treatment:

[0053] Pulse electroplating copper: current density 4A / dm 2 , coating thickness 3μm, surface roughness Ra 0.6μm, conductivity 82% IACS; through 180° reciprocating bending 50 times to verify the bonding strength, the coating did not peel off; thermal shock test ( After 10 cycles, the spatter rate was 2.1%.

[0054] Welding wire performance measurement: Y2O3 mass fraction 1.2%, particle size 5-50nm, distribution uniformity (CV value ≤15%); mechanical properties: yield strength 870MPa, tensile strength 1280MPa, room temperature elongation 21%; 800℃ high temperature creep resistance improved by 42% compared with traditional welding wire, weld strength matching degree 96%, spatter rate 2.1%.

[0055] Example 2

[0056] A method for preparing ODS steel welding wire based on a spray deposition-coordinated arc melting composite process, comprising alcohol ball milling + secondary arc melting + Al2O3 / SiO2-TiO2 composite coating, to enhance oxidation resistance and long-term storage performance; specifically comprising the following steps:

[0057] 1) Surface modification of Y2O3 particles:

[0058] Using alcohol as the medium (alcohol to powder mass ratio of 2:1), the ball mill was filled with alcohol accounting for 40% of its volume; ball milling parameters: ball to powder ratio of 6:1, speed of 600r / min, intermittent ball milling mode (30 minutes of rest after every 3 hours of ball milling, for a total of 30 hours); the alcohol evaporated naturally to a residual content of 0.4wt%, and the Fe coating thickness was 0.2μm. 2) Double vacuum chamber closed melting:

[0059] The vacuum degree of the melting chamber is 4×10-2Pa, the pressure of the spray deposition chamber is 4500Pa, the melting capacity is 4 tons, and the alloy composition is: Cr15%, C 0.3%, W 1.8%, Ti 1.2%, Y 1%, Si 0.6%, and the rest is Fe.

[0060] 3) Spray deposition and powder feeding:

[0061] The superheat of molten steel is +80℃, the outer aperture area of ​​the double nozzle is 20% larger; the single nozzle flow rate is 50kg / min, the nozzle flow rate is 1.2m / min, and the mixed powder is preheated to 680℃.

[0062] 4) Arc gas shielded consumable melting:

[0063] Secondary smelting process: primary current 1800A, secondary current 2200A, protective gas Ar purity 98%; ingot oxygen content 28ppm, nano-oxide dispersed phase size 25nm, volume fraction 0.4%.

[0064] 5) Ingot pretreatment and forging:

[0065] The temperature was raised to 1230°C (heating rate 50°C / h), H2 accounted for 7%, and the hydrogen partial pressure was 0.12atm; the grain size after forging was 35μm, and the dynamic recrystallization rate was 90%.

[0066] 6) Precision hot rolling process enhancement:

[0067] The rough rolling temperature is 1160°C, the deformation is 70%; the finishing rolling temperature is 860°C, the final rolling thickness is 8mm; the surface oxide layer thickness is 8μm, and the grain size is 10μm.

[0068] 7) Composite heat treatment after hot rolling:

[0069] Solution treatment: 1130℃×50min, water cooling to room temperature; aging treatment: 760℃×7h (precipitation phase 40nm)→590℃×20h (spacing 150nm).

[0070] 8) Hot drawing into wire:

[0071] 22 drawing passes, cumulative deformation 90%, annealing gradient 850℃×50s→950℃×40s→1050℃×30s; final wire diameter 1.2mm, texture strength 5.5MRD.

[0072] 9) Surface treatment:

[0073] Spraying Al2O3 / SiO2-TiO2 composite coating: Coating composition: Al2O3 60%, SiO2 25%, TiO2 15%, thickness 12μm; Spraying process: High velocity oxygen fuel (HVOF) spraying, gas pressure 0.7MPa, powder particle size 15-45μm; After 800℃×24h oxidation test, weight gain 1.5mg / cm 2 After the thermal shock test, the coating had no cracks and the spatter rate was 1.8%.

[0074] Welding wire performance measurement: Y2O3 particle size 50nm, yield strength 900MPa, tensile strength 1300MPa, elongation 22%; storage period 26 months (humidity ≤ 30% environment), weld strength matching degree 97%.

[0075] Example 3

[0076] The method for preparing ODS steel welding wire based on the spray deposition and arc melting composite process is to improve the high temperature creep performance and precision machining performance through alcohol ball milling + high W content + three-stage arc melting + ultra-thin copper plating. The specific steps include:

[0077] 1) Surface modification of Y2O3 particles:

[0078] Liquid argon ball milling for 48 hours, rotation speed 700r / min, ball-to-material ratio 10:1, Fe coating thickness 0.5μm.

[0079] 2) Double vacuum chamber closed melting:

[0080] Alloy composition: W 4.5% (other components: Cr 10%, C 0.8%, Ti 1.5%, Y 0.8%, Si 0.2%, balance Fe), smelting quantity 1.8 tons.

[0081] 3) Spray deposition and powder feeding:

[0082] The superheat of the molten steel is +200°C, the nozzle outlet flow rate is 2.0m / min, and the powder is preheated to 700°C; the density of the deposited ingot is ≥99.5%, and the porosity is ≤0.3%.

[0083] 4) Arc gas shielded consumable melting:

[0084] Three smelting processes: currents were 1000A, 2800A, and 3500A, respectively; the oxygen content after smelting was 18ppm; the size of the nano-oxide was 20nm, and the volume fraction was 0.5%.

[0085] 5) Ingot forging:

[0086] Heating to 1250℃ (heating rate 70℃ / h), H2 content 8%, strain rate 1.8s -1 ; The grain size after forging is 30μm and the dynamic recrystallization rate is 95%.

[0087] 6) Precision hot rolling process enhancement:

[0088] The rough rolling temperature is 1200℃, the deformation is 80%; the finishing rolling temperature is 850℃, and the grain size is refined to 8μm.

[0089] Heat treatment and drawing:

[0090] 7) Composite heat treatment after hot rolling:

[0091] Solution treatment at 1150℃ for 30min, aging at 800℃ for 4h → 600℃ for 12h;

[0092] 8) Hot drawing into wire:

[0093] 24 drawing passes, die tolerance ±0.005mm, annealing at 1000℃×30s, cumulative deformation 92%.

[0094] 9) Surface treatment:

[0095] Pulse electroplating copper: current density 5A / dm 2 , coating thickness 1μm, roughness Ra 0.4μm;

[0096] Conductivity 85% IACS, no peeling after 60 bends, spatter rate 1.5%.

[0097] Welding wire performance test: 800℃ creep stress 120MPa (increased by 45%), weld matching degree 97%, wire diameter accuracy ±0.01mm.

[0098] Example 4

[0099] To optimize high-temperature oxidation resistance, Example 4 differs from Example 1 in that:

[0100] (1) Alloy composition adjustment: Cr content increased to 16% (originally 12%), Si content reduced to 0.1% (originally 0.3%), and the remaining components remained unchanged (C 0.5%, W 2.5%, Ti 0.8%, Y 0.3%). After the adjustment, the high-temperature oxidation resistance of the alloy was improved, and the oxidation weight gain at 800°C was reduced to 0.8 mg / cm 2 / h(original 1.2mg / cm 2 / h).

[0101] (2) Optimization of arc melting process: the melting current was increased to 3000A (originally 2500A), and the purity of the protective gas Ar was increased to 99.99% (originally 99.5%); the oxygen content of the ingot was further reduced to 25ppm (originally 35ppm), and the volume fraction of the nano-oxide dispersed phase was increased to 0.45% (originally 0.3%).

[0102] (3) Copper plating process upgrade: double-layer pulse electroplating: first nickel plating the bottom layer (0.2μm, current density 2A / dm 2 ), followed by a copper layer (thickness 4μm, original 3μm); the coating roughness was reduced to Ra 0.4μm (original 0.6μm), and the conductivity was increased to 88% IACS (original 82%).

[0103] Performance measurement: The oxidation rate at 800°C was reduced by 33%, the weld matching degree was improved to 98%, and the spatter rate was further reduced to 1.9%.

[0104] Example 5

[0105] In order to enhance the thermal shock resistance of the coating, the difference between Example 5 and Example 2 is that:

[0106] (1) Optimization of composite coating composition: the proportion of Al2O3 in the coating was increased to 70% (originally 60%), the proportion of SiO2 was reduced to 20% (originally 25%), and 1% Y2O3 nanoparticles were added; the coating thickness was adjusted to 8 μm (originally 12 μm), the spraying process was changed to plasma spraying (originally HVOF), and the porosity was ≤1.5% (originally 2%).

[0107] (2) Adjustment of arc melting times: three melting times (originally two times): the first current is 1500A, the second current is 2000A, and the third current is 2500A; the oxygen content of the ingot is reduced to 20ppm (originally 28ppm), and the dispersed phase size is refined to 18nm (originally 25nm).

[0108] (3) Strengthening of the drawing process: the number of drawing passes increased to 24 (originally 22), the cumulative deformation was 93% (originally 90%), and the wire diameter accuracy was controlled to ±0.008 mm (originally ±0.01 mm); the annealing gradient was adjusted to 900°C → 1000°C → 1100°C (originally 850°C → 950°C → 1050°C), and the texture strength was increased to 6.0 MRD (originally 5.5 MRD).

[0109] Performance measurement: The number of thermal shock cycles of the coating has been increased to 20 (originally 10) without peeling, the tensile strength at 800°C has reached 1350MPa (originally 1300MPa), and the storage period has been extended to 30 months (originally 26 months).

[0110] Example 6

[0111] In order to reduce production costs, the difference between Example 6 and Example 2 is that:

[0112] (1) Simplified surface modification of Y2O3: alcohol medium ball milling was eliminated and dry ball milling (argon protection) was used instead. The ball milling time was shortened to 20 hours (originally 30 hours); the thickness of the Fe coating layer was reduced to 0.1 μm (originally 0.2 μm), and the Y2O3 mass fraction was adjusted to 85% (originally ≥90%).

[0113] (2) Arc melting parameters were downgraded: the melting current was reduced to 1500A (originally 1800-2200A), the purity of the shielding gas Ar was reduced to 95% (originally 98%); the oxygen content of the ingot was increased to 40ppm (originally 28ppm), and the volume fraction of the dispersed phase was reduced to 0.25% (originally 0.4%).

[0114] (3) Composite coating alternative: Using a single Al2O3 coating (5 μm thickness, original composite coating 12 μm), the spraying cost is reduced by 40%; oxidation weight gain at 800 ° C is 2.2 mg / cm 2 (original 1.5mg / cm 2 ), the spatter rate increased to 3.0% (originally 1.8%).

[0115] Performance measurement: Yield strength 820MPa (original 900MPa), tensile strength 1200MPa (original 1300MPa), cost reduced by 25%, suitable for non-nuclear grade conventional high temperature welding.

[0116] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing ODS steel welding wire based on a spray deposition synergistic arc melting composite process, characterized in that: The following steps are involved: 1) Surface modification of Y2O3 particles: ball milling Y2O3 particles and Fe powder in liquid nitrogen or alcohol for 24 to 48 hours at a rotation speed of 450 to 700 r / min and a ball-to-material ratio of 5:1 to 10:1; Fe powder particle size of 20 to 30 μm; Y2O3 mass fraction ≥ 90%; surface metal coating thickness of 0.1 to 0.5 μm; to form a mixed powder of Y2O3 particles and Fe; 2) Closed dual-chamber melting-injection system for melting ODS alloys: The melting chamber and the spray deposition chamber are isolated by a gate valve. The vacuum degree of the melting chamber is ≤5×10-2Pa. The spray deposition chamber is equipped with a high-speed vacuum pump to maintain the ambient pressure ≤5000Pa. Vacuum medium-frequency induction is used in the melting chamber to melt the ODS alloy. The ODS alloy composition is: Cr 8-18%, C 0.1-1%, W 0.5-5%, Ti 0.1-2%, Y 0.05-2%, Si 0.05-1%, and the balance is Fe. The melting capacity is 1-5t. 3) Spray deposition and powder feeding: The superheat of the ODS molten steel is controlled at +50-200°C, and after deslagging and degassing with bottom argon blowing, it is injected into a tundish preheated to ≥1200°C; the mixed powder is preheated to ≥600°C and loaded into the spray deposition area through gas-solid two-phase flow. The mixed powder is embedded in the deposition ingot, and the interface is well bonded; 4) Arc Melting: The deposited ingot is arc melted 1 to 3 times at a melting current of 1000 to 3500 A, with Ar as the shielding gas, and the oxygen content of the ingot after melting is ≤50 ppm; Y2O3 particles are partially dissolved during the arc melting to form a nano-oxide dispersed phase with a size of 5 to 50 nm and a volume fraction of 0.05 to 1%; 5) Ingot pretreatment and forging: The ingot is heated to 800°C at a rate of ≤80°C / h and held for 1 hour to eliminate residual stress; the ingot is further heated to a target temperature of 1180-1250°C at a rate of ≤50°C / h, and then the ingot is stretched and forged into a cube along the height direction; during the holding stage, a H2 / Ar mixed gas is introduced, wherein the H2 accounts for 5-8%, the flow rate is 10-20 L / min, and the hydrogen partial pressure is controlled at 0.05-0.15 atm to promote Y2O3 surface activation; 6) Hot rolling: The cube is subjected to a two-stage process of "high-temperature rough rolling + low-temperature finishing rolling", with a rough rolling temperature of 1150-1200°C to complete 70% deformation and a finishing rolling temperature of 900-850°C to complete the remaining deformation; the hot rolling thickness is 3-15mm to obtain a plate; 7) Composite heat treatment: The plate is first solution treated at 1050-1150°C for 30-60 minutes, and then rapidly cooled to room temperature to retain the supersaturated solid solution; then subjected to two-stage aging treatment: medium-temperature aging at 750-800°C for 4-8 hours and low-temperature stabilization at 550-600°C for 12-24 hours, so that the size of the precipitated phase is stabilized at 5-50 nm; 8) Hot drawing: After composite heat treatment, the plate is continuously drawn by multi-mode for 12-24 times, using carbide dies ±0.01mm, with nano-graphite lubrication, temperature 80-120℃; gradient annealing: 800-1000℃×30-60s, H2 / N2 anti-oxidation; cumulative deformation ≥85% is formed <110> Texture, strength ≥ 5MRD, Y-Ti-O phase stable at 5-50nm; steel wire obtained; 9) Surface treatment: The steel wire is subjected to pulse copper electroplating with a controlled current density of 3-5A / dm 2 , coating 1-5μm, surface roughness Ra≤0.8μm, coating conductivity ≥80%IACS; or spray Al2O3 / SiO2-TiO2 composite anti-oxidation layer.

2. The method for preparing ODS steel welding wire based on a spray deposition synergistic arc melting composite process according to claim 1, characterized in that: In the step 1), the volume of liquid nitrogen in the ball milling tank is filled with 60-90% of the tank volume to ensure that the powder is completely immersed in the low temperature environment; the ball milling is repeated for 24-48 hours in a pattern of ball milling for 2-4 hours and standing for 20-60 minutes, until the liquid nitrogen is completely volatilized to form a dry Fe powder-coated Y2O3 mixed powder.

3. The method for preparing ODS steel welding wire based on a spray deposition synergistic arc melting composite process according to claim 1, characterized in that: In the step 1), the mass ratio of alcohol to the mixed powder is 1:1 to 3:1, and the volume proportion of alcohol is 30 to 50%; the ball milling is repeated for 24 to 48 hours in a mode of ball milling for 2 to 4 hours and standing for 20 to 60 minutes; and the alcohol evaporates naturally until the residual amount is ≤ 0.5 wt%.

4. The method for preparing ODS steel welding wire based on a spray deposition synergistic arc melting composite process according to claim 1, characterized in that: In step 3), double nozzles are arranged horizontally at the bottom of the tundish, with a single nozzle flow rate of 20-60 kg / min, a nozzle outlet flow rate of 1.0-2.0 m / min, and an outer nozzle aperture area 15-25% larger than the inner nozzle aperture area.

5. The method for preparing ODS steel welding wire based on spray deposition and arc melting composite process according to claim 1, characterized in that: In the step 4), the melting voltage is 20 to 50 V, and the volume fraction of the protective gas Ar is 95% to 99%.

6. The method for preparing ODS steel welding wire based on a spray deposition synergistic arc melting composite process according to claim 1, characterized in that: In the step 5), the deformation amount per pass during forging is 15-25%, and the strain rate is 0.5-2s -1 .

7. The method for preparing ODS steel welding wire based on a spray deposition combined with arc melting composite process according to claim 1, characterized in that: In step 6), after rough rolling, the grain size is refined to 20-50 μm, and the dynamic recrystallization rate is ≥80%; the final rolling temperature is controlled to have a deviation of ≤±10°C, and the austenite is rolled in the non-recrystallized zone, and the grains are further refined to 5-15 μm; the surface oxide layer thickness is ≤10 μm, and the subsequent drawing requirements can be met without additional pickling.

8. The method for preparing ODS steel welding wire based on a spray deposition synergistic arc melting composite process according to claim 1, characterized in that: In the step 7), the step cooling rate during the two-stage aging treatment is ≤20°C / h.

9. The method for preparing ODS steel welding wire based on a spray deposition synergistic arc melting composite process according to claim 1, characterized in that: In the step 8), the gradient annealing temperature is increased in three stages from 800°C to 950°C to 1000°C, with a single-stage holding time of 30-60s, and a mixed protective atmosphere of H2 / N2=1:3 volume ratio is used throughout the process; <110> The axial preferred orientation texture and the phase spacing of the Y-Ti-O precipitated phase are maintained at 100-200nm.

10. The method for preparing ODS steel welding wire based on a spray deposition synergistic arc melting composite process according to claim 1, characterized in that: In step 9), the thickness of the Al2O3 / SiO2-TiO2 composite anti-oxidation layer is 8-15 μm, and the weight gain per unit area after the 800°C oxidation test is ≤2 mg / cm 2 ; Implement thermal shock cycle ( The spatter rate of the treated layer is ≤2.5% and there is no peeling defect.