Co-cr-mo high temperature alloy welding wire and method of making

Abstract

The present application relates to a kind of Co-Cr-Mo high temperature alloy welding wire and its preparation method, belong to high temperature alloy welding wire material technical field, at least to solve one of the problems of existing Co-Cr-Mo alloy welding wire brittleness, size precision is poor, surface quality is poor, welding process and poor wear resistance.It includes according to the component of the welding wire to be prepared, by vacuum induction melting, high temperature alloy raw material is melted and cast into electrode;The electrode is remelted and atomized powder in vacuum melting gas atomization device;Atomized powder is screened, and powder of predetermined particle size is obtained;After screening, powder is loaded into sleeve sheath and degassing treatment, vacuum and sealed packaging;The packaged sheath is subjected to hot isostatic pressing treatment;The ingot is subjected to stress relief annealing treatment;Annealed ingot is cut by wire cutting machine along the axial direction, then ground, vacuum low temperature heat treatment and magnetic polishing, to obtain welding wire product.The welding wire prepared by the present application has good performance.

Description

Technical Field

[0001] This invention relates to the field of high-temperature alloy welding wire materials, and in particular to a Co-Cr-Mo high-temperature alloy welding wire and its preparation method. Background Technology

[0002] In aero-engines and gas turbines, low-pressure turbine blades and guide vanes with serrated crown structures typically require the overlay of a high-performance wear-resistant alloy layer to ensure stable operation. The main function of this wear-resistant layer is to reduce wear caused by collisions between adjacent blade crowns during operation, prevent increased blade vibration due to widening gaps, and thus avoid blade cracking and failure. Therefore, the wear-resistant layer material used for such components must possess excellent high-temperature wear resistance, oxidation resistance, and good weldability.

[0003] Co-Cr-Mo alloys, as a typical cobalt-based wear-resistant alloy, are widely studied for use in wear-resistant layers due to their high-hardness Laves reinforcing phase. Currently, the preparation of Co-Cr-Mo alloy welding wires mostly employs traditional casting processes. This process has inherent limitations, leading to the following problems with the produced welding wires: high material brittleness, making it difficult to prepare wires of sufficient length; internal defects such as shrinkage cavities and segregation are prone to occur. Existing welding wires have poor surface cleanliness, which can introduce molten pooling during welding, affecting weld quality. Furthermore, cast welding wires have poor processability, making it difficult to meet the high-precision and uniform preparation requirements of wear-resistant layers for large-sized turbine blades with complex crown structures.

[0004] Therefore, developing a method for preparing Co-Cr-Mo alloy welding wire with high purity, good toughness, high dimensional accuracy and excellent surface quality is of great significance for improving the performance and reliability of wear-resistant weld overlay. Summary of the Invention

[0005] Based on the above analysis, the present invention aims to provide a Co-Cr-Mo high-temperature alloy welding wire and its preparation method, at least to solve one of the following problems existing in the Co-Cr-Mo alloy welding wire prepared by the existing Co-Cr-Mo alloy welding wire preparation method: 1. high brittleness and many structural defects; 2. poor dimensional accuracy; 3. poor surface quality; 4. poor welding processability and wear resistance.

[0006] The objective of this invention is mainly achieved through the following technical solutions: This invention provides a method for preparing a Co-Cr-Mo high-temperature alloy welding wire, comprising the following steps: S1: According to the composition of the Co-Cr-Mo high-temperature alloy welding wire to be prepared, the high-temperature alloy raw materials that meet the composition requirements are melted and cast into electrodes by vacuum induction melting. S2: The electrode is remelted and atomized into powder in a vacuum melting gas atomization device; S3: The atomized powder is sieved to remove particles with a particle size of less than 30μm and greater than 100μm, so as to obtain powder with a predetermined particle size of 30-100μm. S4: After sieving, the powder is placed into a sleeve for degassing, vacuumed, and sealed. S5: The encapsulated casing is subjected to hot isostatic pressing to obtain a dense ingot. S6: The billet is subjected to stress-relief annealing in a box-type resistance furnace; S7: The annealed billet is wire-cut along the axial direction using a wire cutting machine to obtain the first coarse wire product; S8: The first coarse shredded product is ground using a centerless grinder to remove the influence layer of wire cutting, and then finely ground to the finished shredded product size to obtain the second coarse shredded product; S9: The second coarse shredded product is subjected to vacuum low-temperature heat treatment to obtain the third coarse shredded product; S10: The third coarse wire is magnetically polished to obtain the finished Co-Cr-Mo high-temperature alloy welding wire.

[0007] Furthermore, in step S1, the casting temperature is 1400-1500℃.

[0008] Furthermore, in step S2, during the remelting process, the melt superheat is 150-300°C and the melting time is 25-40 minutes.

[0009] Furthermore, in step S2, during the atomization powder production process, the atomization pressure difference is 5000-15000 Pa, the melt diameter at the outlet of the guide tube is 4-5 mm, and the atomization gas pressure is 5-8 MPa.

[0010] Furthermore, in step S4, the degassing temperature is 300-600℃, and the degassing holding time is 12-48h.

[0011] Furthermore, in step S5, the hot isostatic pressing temperature is 1050-1150℃, the hot isostatic pressing pressure is 140-160MPa, and the hot isostatic pressing time is 4-8h.

[0012] Furthermore, in step S6, the annealing temperature is 1000-1100℃, and the holding time is 1-3 hours.

[0013] Furthermore, in step S9, the vacuum low-temperature heat treatment temperature is 200-400℃, and the holding time is 0.5-2h.

[0014] Furthermore, in step S10, the polishing time is 2-10 minutes.

[0015] The present invention also provides a Co-Cr-Mo high-temperature alloy welding wire, which is prepared by the above preparation method. Its chemical composition by weight percentage is: Cr: 16.5-18.5%, Mo: 27.0-30.0%, Si: 3.0-3.8%, with the balance being Co and unavoidable impurities.

[0016] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. The method of this invention effectively reduces the oxygen content (and inclusions) of the powder by optimizing vacuum induction melting combined with gas atomization powdering process and strictly controlling superheat, atomization parameters, and sieving particle size. Through a specific range of hot isostatic pressing parameters and a precisely controlled stress-relief annealing process, the fine and dispersed distribution of the strengthening Laves phase is promoted, avoiding its large skeletal brittle structure. While maintaining high hardness, the overall toughness of the alloy is improved, and a highly refined and uniform microstructure is obtained. The "wire cutting + precision grinding" forming method avoids the incompatibility of traditional drawing with brittle materials, ensuring high precision and consistency of the welding wire diameter. Subsequent vacuum low-temperature heat treatment and magnetic polishing significantly improve the surface cleanliness and smoothness of the welding wire, reducing problems such as arc ignition difficulties, spatter, and slag in the molten pool during welding.

[0017] 2. The welding wire prepared by the method of the present invention exhibits good arc stability, molten metal fluidity and wettability when surfacing using processes such as argon arc welding due to its high purity, uniform and fine structure, and excellent size and surface quality. The resulting wear-resistant layer has a uniform structure, few defects, and reliable high-temperature wear resistance and oxidation resistance, which can meet the stringent requirements of high-end equipment components such as turbine blades for long-term vibration and wear protection.

[0018] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0019] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. Figure 1 This is a scanning electron microscope backscattered electron image of the welding wire prepared in Example 1 of the present invention; Figure 2 The backscattered electron image of the welding wire prepared for Comparative Example 1 is shown in the scanning electron microscope image. Detailed Implementation

[0020] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0021] This invention provides a method for preparing a Co-Cr-Mo high-temperature alloy welding wire, comprising the following steps: S1: According to the composition of the Co-Cr-Mo high-temperature alloy welding wire to be prepared, the high-temperature alloy raw materials that meet the composition requirements are melted and cast into electrodes by vacuum induction melting. The casting temperature is 1400-1500℃. Below 1400℃, the melt lacks fluidity, making it difficult to fill the electrode mold smoothly and completely during vacuum induction melting, easily leading to casting defects such as cold shuts and incomplete filling, affecting the uniformity and density of subsequent electrodes. Excessively high temperatures (e.g., well above 1500℃), while improving fluidity, can cause a large temperature difference between the melt and the mold, damaging the toughness of the final product. Simultaneously, within the reasonable high-temperature range of 1400-1500℃, the removal of gases (such as O, N, and H) and the volatilization of low-melting-point impurities (such as S and P) are facilitated, improving melt purity and effectively suppressing excessive volatilization of high vapor pressure elements such as Cr and Si, ensuring accurate recovery of key alloying elements and guaranteeing that the composition meets the design range.

[0022] S2: The electrode is remelted and atomized into powder in a vacuum melting gas atomization device; The melting crucible is made of Al-Si refractory material, the superheat of the melt is controlled within the range of 150-300℃, and the melting time is 25-40min; the atomizing gas is high-purity argon, the atomization pressure difference is 5000-15000Pa, the melt diameter at the outlet of the guide tube is 4-5mm, and the atomizing gas pressure is 5-8MPa.

[0023] It should be noted that Co-Cr-Mo alloy melt has high chemical activity and severely corrodes common refractory materials (such as magnesium oxide and aluminum oxide). The melting crucible is made of Al-Si refractory materials (such as mullite or Al2O3-SiO2 composite materials) because it can form a stable high-viscosity liquid phase layer at the alloy melting temperature. The poor wettability between the liquid and the melt can significantly reduce the erosion and scouring of the crucible by the melt, thereby minimizing the spalling of refractory material particles into the melt and avoiding the introduction of foreign inclusions such as Al2O3 and SiO2 into the final powder and welding wire, thus ensuring the high cleanliness of the alloy powder.

[0024] Melt superheat is a key physical parameter for controlling the morphology and particle size of atomized powder. If the temperature is too low (<150℃), the melt viscosity increases sharply, fluidity deteriorates, and the powder is prone to solidification and blockage in the guide tube, leading to atomization interruption. If the temperature is too high (>300℃), the reduced surface tension of the melt, while beneficial for atomization, exacerbates the oxidation of droplets during flight and the adhesion of powder after cooling and solidification, increasing the oxygen content of the powder and worsening fluidity, leading to powder particle oxidation. A superheat of 150-300℃ ensures good melt fluidity, achieves stable atomization, and yields powder with high sphericity and low oxygen content. If the melting time is too short (<25min), refining is insufficient, and gases (such as H2, O2) and low-melting-point impurities (such as S, P) in the melt are not adequately removed, affecting powder purity. If the time is too long (>40min), under vacuum or protective atmosphere, active elements in the melt will volatilize and burn off due to prolonged high-temperature exposure, causing the alloy composition to deviate from the design value and potentially introducing inclusions.

[0025] The atomizing pressure difference is the main driving force for the gas to break up the melt flow. If the pressure difference is too small (<5000Pa), the gas kinetic energy is insufficient, and the melt flow is not broken up sufficiently, which easily produces a large number of coarse particles (>150μm) and trailing filaments, reducing the yield of qualified powder. If the pressure difference is too large (>15000Pa), the gas flow rate is too high, which will cause excessive cooling and disturbance to the melt flow, resulting in an excessively wide powder particle size distribution and a surge in the proportion of fine powder (<20μm). Fine powder has a higher specific surface area, which will significantly adsorb oxygen and increase the difficulty of subsequent degassing. An atomizing pressure difference of 5000-15000Pa is the key to achieving efficient and controllable crushing and obtaining the target particle size distribution. Gas pressure and atomization pressure difference work together to determine the flow rate and velocity of the atomizing gas. If the pressure is too low (<5MPa), the gas flow rate is insufficient, making it impossible to form a stable, high-kinetic-energy atomizing cone. The cooling rate is low, and the powder is prone to sticking together and has poor sphericity. If the pressure is too high (>8MPa), the gas velocity is extremely fast, and the cooling rate of the droplets is too high, which may cause the droplets to solidify before complete atomization, forming irregular shapes. At the same time, the high-speed airflow can easily re-entrain the solidified fine powder into the high-temperature zone, increasing equipment energy consumption and wear.

[0026] The diameter of the melt at the outlet of the guide tube determines the melt flow rate per unit time and the stability of the initial flow column. If the diameter is too small (<4mm), the melt flow rate is low, the crushing efficiency is poor, and the small flow column is extremely sensitive to airflow disturbances, making it easy to break and form irregular large particles. If the diameter is too large (>5mm), the melt flow column is thick, the surface area of ​​the melt per unit mass is small, and extremely high gas kinetic energy is required for complete crushing. Under a given gas pressure, it is easy to cause incomplete atomization, forming coarse powder or gas trapped inside the particles.

[0027] S3: The atomized powder obtained in step S2 is sieved to remove particles with a particle size of less than 30 μm and greater than 100 μm, so as to obtain powder with a predetermined particle size of 30-100 μm. It should be noted that fine powders with a particle size of less than 30μm have an extremely large specific surface area. During the cooling, collection, and storage processes after atomization, these fine powders will significantly adsorb oxygen and moisture from the environment, forming a thick oxide film. In subsequent steps, it is difficult to completely remove the chemically adsorbed oxygen. High oxygen content entering the final product will seriously impair the toughness, welding processability (increasing spatter and porosity), and high-temperature performance of the welding wire. By actively removing fine powder, the overall oxygen content and surface activity of the powder can be significantly reduced from the source. During atomization, a small amount of irregular powder, such as flakes, trailing filaments, or agglomerated particles, will inevitably be generated. These particles usually have poor flowability and may become stress concentration points or sources of contamination in subsequent processing. Mechanical sieving can effectively filter out irregularly shaped powders and inclusions, improving the purity of the powder. Powders with a particle size of 30-100μm have a moderate particle size and a narrow distribution, which can achieve a high initial filling density and a uniform filling structure during subsequent processes. This is beneficial for obtaining ingots with high density and low porosity, while reducing local shrinkage and deformation caused by excessive differences in powder size.

[0028] S4: The sieved powder obtained in step S3 is loaded into a sleeve for degassing, vacuumed and sealed. Specifically, the diameter of the sleeve is 150-200mm, and the length is 400-630mm. The degassing temperature is 300-600℃, and the degassing and heat preservation time is 12-48h.

[0029] It should be noted that the core purpose of degassing is to remove as much water vapor, gas, and some weakly chemically adsorbed oxygen as possible from the powder surface before densification. If the temperature is too low, it will not provide enough energy to overcome the binding energy between gas molecules (especially chemically adsorbed oxygen) and the powder surface, resulting in low degassing efficiency and high residual gas content. If the temperature is too high, although it can accelerate desorption, it will cause a significant thickening of the oxide layer on the powder surface. The oxide layer is difficult to completely dissolve or reduce through solid-state diffusion during subsequent hot isostatic pressing and will remain in the material as inclusions, damaging toughness and purity. A degassing temperature of 300-600℃ can effectively drive gas desorption and inhibit secondary oxidation of the powder surface. If the degassing time is too short, the gas diffusion will be insufficient, especially the trace amounts of gas trapped inside the powder and particles in the central area of ​​the coating cannot be effectively discharged; if the degassing time is too long, the surface of certain elements may agglomerate on the powder surface due to prolonged heating, and the improvement in degassing effect will not be significant; a degassing holding time of 12-48 hours and a degassing temperature of 300-600℃ can effectively remove most of the removable gases and stably control the oxygen, nitrogen and other gas contents of the powder at a low level, thereby improving the purity of the alloy.

[0030] S5: The encapsulated package from step S4 is subjected to hot isostatic pressing to obtain a dense ingot. Specifically, the hot isostatic pressing temperature is 1050-1150℃, the hot isostatic pressing pressure is 140-160MPa, and the hot isostatic pressing time is 4-8h.

[0031] It should be noted that in this step, the synergistic effect of hot isostatic pressing (HIP) temperature, pressure, and time is used to achieve complete powder densification while precisely controlling the alloy's microstructure. The strengthening phase (Laves phase) in Co-Cr-Mo alloys exhibits a significant growth tendency at high temperatures. If the HIP temperature is too high, the Laves phase will rapidly coarsen, severely impairing the alloy's toughness and processability. If the temperature is too low, the oxide film on the powder particle surface is difficult to dissolve through diffusion, and insufficient atomic diffusion kinetics result in low interparticle bonding strength, incomplete pore closure, and difficulty in achieving complete densification. Within the HIP temperature range of 1050-1150℃, the powder particles possess sufficient plastic deformation capacity and surface diffusion rate to achieve densification, while simultaneously suppressing excessive coarsening of the strengthening phase (Laves phase), thus maintaining a relatively fine and dispersed morphology. For Co-Cr-Mo alloy powders, densification requires a high stress level. Insufficient pressure at 1050-1150℃ cannot completely overcome the powder's yield strength and work hardening, resulting in high residual porosity and severely affecting the mechanical properties and subsequent machinability of the ingot. Excessive pressure, while beneficial for densification, places higher demands on hot isostatic pressing equipment, increasing costs, and excessive plastic deformation may introduce unfavorable textures or internal stresses. A pressure range of 140-160 MPa, combined with a temperature range of 1050-1150℃, can provide sufficient and efficient densification driving force for the alloy powder, prompting plastic deformation, creep, and breakage of the surface oxide film in the powder particles to eliminate interparticle porosity. The holding time during hot isostatic pressing (HIP) ensures the full completion of alloy densification and microstructure evolution. Too short a time results in insufficient diffusion, potentially leading to incompletely healed micropores or weak particle interfaces within the alloy, resulting in weak performance in those areas. Too long a time, in the later stages of holding, offers very limited density improvement and instead provides more time for Laves phase coarsening, potentially causing its average size to exceed the ideal range, while also increasing energy consumption and production cycle. A holding time of 4-8 hours, matched with the aforementioned HIP temperature and pressure parameters, ensures billet density while suppressing Laves phase coarsening, resulting in a uniform, stable, and finely dispersed distribution of the Laves phase.

[0032] S6: The billet is subjected to stress-relief annealing in a box-type resistance furnace; Specifically, the annealing temperature is 1000-1100℃, held for 1-3 hours, then furnace cooled to below 200℃ before being air-cooled. It should be noted that although hot isostatic pressing (HIP) achieves densification, the intense plastic deformation and diffusion process accumulates a large amount of residual stress within the billet. An annealing temperature of 1000-1100℃ provides sufficient atomic diffusion motive force, effectively promoting dislocation recombination and subgrain merging, and eliminating macroscopic residual stress generated during HIP. If the temperature is too high, it can easily lead to the growth of the strengthening phase (Laves phase), disrupting its fine, dispersed state formed after HIP and impairing the material's toughness. If the temperature is too low, insufficient atomic diffusion motive force results in incomplete stress elimination, and the residual stress can cause uneven stress release during subsequent wire cutting, leading to wire warping, deformation, and loss of dimensional accuracy. If the holding time is too short, heat and diffusion may not penetrate evenly to the billet core, resulting in uneven stress distribution across the cross-section and high residual stress in the core. If the holding time is too long, it increases energy consumption, prolongs the cycle time, and can easily cause the Laves phase to slowly coarsen. A holding time of 1-3 hours ensures the sufficiency and uniformity of the stress elimination process.

[0033] S7: The annealed billet is wire-cut along the axial direction using a wire cutting machine to obtain the first coarse wire product; Specifically, the diameter of the first coarse shred is (1.0-1.8) mm + (0.2-0.5) mm, where 1.0-1.8 mm is the diameter of the finished shred and 0.2-0.5 mm is the allowance for subsequent polishing.

[0034] S8: The first coarse shredded product is ground using a centerless grinder to remove the influence layer of wire cutting, and then finely ground to the finished shredded product size to obtain the second coarse shredded product; It should be noted that soap-based grinding fluids should be avoided during the grinding process to prevent their alkaline components from reacting chemically with active elements (such as Cr) on the alloy surface, forming difficult-to-remove soap residues and damaging the surface passivation film. At the same time, organic matter should be prevented from pyrolyzing in subsequent heat treatment to generate gas or solid carbon pollution, thereby ensuring the final surface cleanliness of the welding wire, ensuring the stability of the welding process, and preventing weld porosity defects.

[0035] S9: The second coarse shredded product is subjected to vacuum low-temperature heat treatment to obtain the third coarse shredded product; Specifically, the vacuum low-temperature heat treatment temperature is 200-400℃, and the holding time is 0.5-2h.

[0036] It should be noted that the vacuum low-temperature heat treatment temperature is 200-400℃, and the holding time is 0.5-2 hours. Through gentle heating and a vacuum environment, water vapor, gas, grinding fluid residue, and some weakly bound contaminants physically adsorbed on the surface of the shredded wire due to grinding and contact with air are effectively removed. Simultaneously, significant oxidation or microstructural changes on the alloy surface are avoided, thus significantly improving the surface chemical cleanliness without substantially altering the properties of the shredded wire itself. Temperatures below 200℃ result in insufficient thermal energy, low desorption efficiency, and insignificant cleaning effects. Temperatures above 400℃ may cause selective oxidation or bulk diffusion of certain alloying elements (such as Cr), leading to slight thickening of the surface oxide layer or compositional segregation, which in turn introduces a surface condition unfavorable to subsequent welding or polishing. Too short a time may result in uneven treatment or incomplete desorption; too long a time increases energy consumption and production cycle. This time range, matched with the aforementioned temperature range, ensures improved surface cleanliness of the shredded wire. The reduced surface activity after this treatment is more conducive to achieving a high gloss finish through subsequent magnetic polishing.

[0037] S10: The third coarse wire is magnetically polished to obtain the finished Co-Cr-Mo high-temperature alloy welding wire.

[0038] Specifically, the polishing time is 2-10 minutes, the diameter of the magnetic polishing needles is 0.8 mm and / or 1.0 mm, and the ratio of the number of magnetic polishing needles with a diameter of 0.8 mm to the number of magnetic polishing needles with a diameter of 1.0 mm is 0.5-2. The amount of polishing liquid added is 3-10% of the total polishing medium volume.

[0039] It should be noted that if the polishing time is too short, the polishing energy input will be insufficient, failing to effectively eliminate the micro-scratches, burrs, and surface alteration layers generated by grinding, resulting in insignificant improvement in surface finish. Conversely, if the time is too long, it may cause minor dimensional losses in the welding wire exceeding tolerances, or excessive impact may create new micro-pits on the surface, thereby damaging surface integrity. A polishing time of 2-10 minutes can optimize surface quality while ensuring wire dimensional accuracy. Polishing needles of a single size have limitations when polishing complex curved surfaces or surface features of different scales. A fine needle with a diameter of 0.8mm has better penetration and flexibility, effectively entering micro-scratches, grooves, and micro-recessed areas on the welding wire surface for fine grinding, improving surface finish. A coarse needle with a diameter of 1.0mm has greater mass and kinetic energy, removing macro-burrs, rounding sharp edges, and homogenizing the macro-surface contours. Setting the ratio of fine to coarse needles between 0.5 and 2 (i.e., the ratio of fine to coarse needles can be adjusted between 1:2 and 2:1) creates a synergistic multi-scale polishing mechanism. When the proportion of fine needles is higher (close to 2:1), the polishing effect focuses more on finishing and smoothing; when the proportion of coarse needles is higher (close to 1:2), it focuses more on deburring and shaping. The ratio range of 0.5-2 provides process flexibility, allowing for optimization based on the surface condition left by the previous grinding process (such as the degree of burrs and roughness) to achieve high-efficiency and high-quality polishing results. If the ratio exceeds this range, such as too many fine needles, the macroscopic shaping ability will be insufficient; if there are too many coarse needles, new and deeper impact marks will easily be left on the surface.

[0040] Polishing slurry plays multiple roles in magnetic polishing, including lubrication, cooling, cleaning, and rust prevention. The amount added should be 3-10% of the total polishing medium (polishing needle + welding wire + polishing slurry). If the amount added is too low, the liquid will not adequately coat and lubricate all surfaces of the polishing needle and welding wire, leading to frictional heat buildup, dry adhesion or scratches on the polishing needle and welding wire, and the generated fine abrasive particles cannot be removed in time, potentially causing secondary scratches. If the amount added is too high, the excess liquid will significantly buffer the impact kinetic energy of the polishing needle, reducing polishing efficiency and forcing a longer polishing time. It may also trigger electrochemical corrosion on the welding wire surface. An addition of 3-10% can form a uniform and effective fluid medium film, ensuring sufficient lubrication and cooling while maintaining sufficient kinetic energy for the polishing needle to perform mechanical action, and promptly flushing away abrasive particles to obtain a clean and bright surface.

[0041] The present invention also provides a Co-Cr-Mo high-temperature alloy welding wire, which is prepared by the above preparation method. Its chemical composition by weight percentage is: Cr: 16.5-18.5%, Mo: 27.0-30.0%, Si: 3.0-3.8%, with the balance being Co and unavoidable impurities.

[0042] The microstructure of the Co-Cr-Mo high-temperature alloy welding wire prepared by this invention includes a γ-Co solid solution matrix and a Mo-rich Laves reinforcing phase. The volume fraction of the Mo-rich Laves reinforcing phase is 50-55%. The Mo-rich Laves phase is small and irregular in shape and is uniformly dispersed in the matrix. The average size of the Laves phase is 1.0-3.0 μm.

[0043] The Co-Cr-Mo high-temperature alloy welding wire prepared by this invention has a high dimensional accuracy with a diameter standard deviation ≤0.1mm (e.g., 0.05-0.06mm); a surface oxygen content ≤4.0 at.% (e.g., 3.2-3.8 at.%); and a 100% success rate in 20 consecutive arc ignitions. After the Co-Cr-Mo high-temperature alloy welding wire is used to prepare the weld overlay, the porosity of the weld overlay is <0.1%, and the wear rate at 850℃ is [not specified]. (like The tolerance for microhardness fluctuation (HV0.3) is ≤20HV (e.g., 13-18HV).

[0044] Example 1 The chemical composition of the Co-Cr-Mo high-temperature alloy welding wire to be prepared in this embodiment, by weight percentage, is: Cr: 17.5%, Mo: 28.5%, Si: 3.4%, with the balance being Co and unavoidable impurities.

[0045] Prepared by the following method: S1: According to the composition of the Co-Cr-Mo high-temperature alloy welding wire to be prepared, the high-temperature alloy raw materials that meet the composition requirements are melted and cast into electrodes by vacuum induction melting at a casting temperature of 1450℃. S2: The electrode is remelted and atomized into powder in a vacuum melting gas atomization device; The melting crucible is made of Al-Si refractory material, the melt superheat is 200℃, the melting time is 30min; the atomizing gas is high-purity argon, the atomization pressure difference is 10000Pa, the melt diameter at the outlet of the guide tube is 4.5mm, and the atomizing gas pressure is 6MPa.

[0046] S3: The atomized powder obtained in step S2 is sieved to remove particles with a particle size of less than 30 μm and greater than 100 μm, so as to obtain powder with a predetermined particle size of 30-100 μm. S4: The sieved powder obtained in step S3 is loaded into a sleeve for degassing, vacuumed and sealed. The diameter of the sleeve is 190 mm and the length is 500 mm. The degassing temperature is 450℃, and the degassing holding time is 24 hours.

[0047] S5: The encapsulated package from step S4 is subjected to hot isostatic pressing to obtain a dense ingot. The hot isostatic pressing temperature was 1100℃, the hot isostatic pressing pressure was 150MPa, and the hot isostatic pressing time was 7h.

[0048] S6: The billet is subjected to stress-relief annealing in a box-type resistance furnace; The annealing temperature is 1050℃, held for 2 hours, and then cooled in the furnace to below 200℃ before being air-cooled.

[0049] S7: The annealed billet is wire-cut along the axial direction using a wire cutting machine to obtain the first rough wire. The diameter of the first rough wire is Φ1.6mm + 0.3mm, where Φ1.6mm is the diameter of the finished wire and 0.3mm is the allowance for subsequent polishing.

[0050] S8: The first coarse shredded product is ground using a centerless grinder to remove the influence layer of wire cutting, and then finely ground to a finished shredded product size of Φ1.6mm to obtain the second coarse shredded product; S9: The second coarse shredded product is subjected to vacuum low-temperature heat treatment at 300°C for 1 hour to obtain the third coarse shredded product; S10: The third coarse wire is magnetically polished to obtain the finished Co-Cr-Mo high-temperature alloy welding wire.

[0051] The polishing time is 5 minutes, the diameter of the magnetic polishing needles is 0.8 mm and / or 1.0 mm, and the ratio of the number of magnetic polishing needles with a diameter of 0.8 mm to the number of magnetic polishing needles with a diameter of 1.0 mm is 1:1. The amount of polishing liquid added is 5% of the total polishing medium volume.

[0052] Figure 1 The scanning electron microscope backscattered electron image (BEI) of the welding wire prepared in this embodiment shows that the light color represents the Mo-rich Laves phase, which is small and irregular in shape; the dark color represents the γ-Co solid solution matrix; there is no eutectic phase consisting of Co-based γ phase and Mo-rich Laves phase.

[0053] Example 2 This embodiment prepares a Co-Cr-Mo high-temperature alloy welding wire with the composition of Example 1. The preparation method is similar to that of Example 1, except that: In step S5, the hot isostatic pressing temperature is 1080℃, the pressure is 145MPa, and the holding time is 6h. In step S6, the annealing temperature is 1080℃, and the holding time is 1.5h. Then, the furnace is cooled to below 200℃ and then the furnace is air-cooled.

[0054] Example 3 This embodiment prepares a Co-Cr-Mo high-temperature alloy welding wire with the composition of Example 1. The preparation method is similar to that of Example 1, except that: In step S5, the hot isostatic pressing temperature is 1120℃, the pressure is 155MPa, and the holding time is 5h. In step S6, the annealing temperature is 1020℃, and the holding time is 3 hours. Then, the furnace is cooled to below 200℃ and the furnace is air-cooled.

[0055] Comparative Example 1 Using an alloy with the same composition as in Example 1, the alloy was directly cast into Φ50mm ingots after vacuum induction melting. After homogenization treatment at 1150℃ for 10 hours, steps S7-S10 were performed.

[0056] Figure 2 The backscattered electron image (BEI) of the scanning electron microscope is shown in this comparative example. The morphology of the light and dark patterns is: a eutectic phase of Co-based γ phase + Mo-rich Laves phase; showing a coarse Laves phase framework.

[0057] Comparative Example 2 The Co-Cr-Mo high-temperature alloy welding wire prepared in this comparative example with the composition of Example 1 was prepared in a similar process to that of Example 1, except that step S6 stress-relief annealing was omitted and the wire was cut directly after hot isostatic pressing.

[0058] Comparative Example 3 The Co-Cr-Mo high-temperature alloy welding wire of the comparative example preparation Example 1 was prepared in a similar process to that of Example 1, except that steps S9 and S10 were omitted and the finished welding wire was obtained after polishing in step S8.

[0059] Comparative Example 4 The Co-Cr-Mo high-temperature alloy welding wire prepared in this comparative example has a similar preparation process to that of Example 1, except that: In step S2, the melt superheat is 380°C and the atomizing gas pressure is increased to 9 MPa; In step S5, the hot isostatic pressing temperature is 1180℃, and the holding time is shortened to 2.5h; In step S6, the annealing temperature is reduced to 950℃ and the holding time is shortened to 0.5h; The remaining steps are the same as in Example 1.

[0060] Table 1 is a comparison table of the welding wire performance and welding processability of the examples and comparative examples; Table 2 is a comparison table of the microstructure and wear resistance of the weld overlay layers prepared on DZ125 substrates by all welding wires of the examples and comparative examples under the same optimized TIG parameters.

[0061] Table 1. Comparison of welding wire performance and welding processability between the examples and comparative examples.

[0062] Table 2 Comparison of weld overlay microstructure and wear resistance of the examples and comparative examples

[0063] The preparation methods and parameters of Examples 1-3 meet the requirements of this invention, and the performance of the welding wires is superior to all comparative examples. Comparative Example 1 uses a traditional casting method to prepare the welding wire, resulting in poor performance in all aspects. Comparative Example 2 lacks a stress-relief annealing step, leading to poor toughness in the prepared welding wire. Comparative Example 3 lacks a surface treatment step, resulting in high oxygen content on the surface of the welding wire during welding. Several process parameters in Comparative Example 4 do not meet the requirements of this invention; even if the preparation method of this invention is still used, the superior effects of this invention cannot be obtained, demonstrating the non-obviousness and synergy of the parameter combinations in this invention.

[0064] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a Co-Cr-Mo high-temperature alloy welding wire, characterized in that, Includes the following steps: S1: According to the composition of the Co-Cr-Mo high-temperature alloy welding wire to be prepared, the high-temperature alloy raw materials that meet the composition requirements are melted and cast into electrodes by vacuum induction melting. S2: The electrode is remelted and atomized into powder in a vacuum melting gas atomization device; S3: The atomized powder is sieved to remove particles with a particle size of less than 30μm and greater than 100μm, so as to obtain powder with a predetermined particle size of 30-100μm. S4: After sieving, the powder is placed into a sleeve for degassing, vacuumed, and sealed. S5: The encapsulated casing is subjected to hot isostatic pressing to obtain a dense ingot. S6: The billet is subjected to stress-relief annealing in a box-type resistance furnace; S7: The annealed billet is wire-cut along the axial direction using a wire cutting machine to obtain the first coarse wire product; S8: The first coarse shredded product is ground using a centerless grinder to remove the influence layer of wire cutting, and then finely ground to the finished shredded product size to obtain the second coarse shredded product; S9: The second coarse shredded product is subjected to vacuum low-temperature heat treatment to obtain the third coarse shredded product; S10: The third coarse wire is magnetically polished to obtain the finished Co-Cr-Mo high-temperature alloy welding wire; In step S4, the degassing temperature is 300-600℃, and the degassing holding time is 12-48h; In step S5, the hot isostatic pressing temperature is 1050-1150℃, the hot isostatic pressing pressure is 140-160MPa, and the hot isostatic pressing time is 4-8h. In step S6, the annealing temperature is 1000-1100℃, and the holding time is 1-3 hours; In step S9, the vacuum low-temperature heat treatment temperature is 200-400℃, and the holding time is 0.5-2h; The microstructure of the Co-Cr-Mo high-temperature alloy welding wire includes a γ-Co solid solution matrix and a Mo-rich Laves reinforcing phase. The volume fraction of the Mo-rich Laves reinforcing phase is 50-55%. The Mo-rich Laves phase is small, irregular in shape, and uniformly dispersed in the matrix. The average size of the Laves phase is 1.0-3.0 μm.

2. The preparation method according to claim 1, characterized in that, In step S1, the casting temperature is 1400-1500℃.

3. The preparation method according to claim 1, characterized in that, In step S2, during the remelting process, the melt superheat is 150-300℃ and the melting time is 25-40min.

4. The preparation method according to claim 3, characterized in that, In step S2, during the atomization powder production process, the atomization pressure difference is 5000-15000 Pa, the melt diameter at the outlet of the guide tube is 4-5 mm, and the atomization gas pressure is 5-8 MPa.

5. The preparation method according to claim 1, characterized in that, In step S4, the degassing temperature is 450-600℃, and the degassing holding time is 12-24h.

6. The preparation method according to claim 1, characterized in that, In step S5, the hot isostatic pressing temperature is 1050-1120℃, the hot isostatic pressing pressure is 145-160MPa, and the hot isostatic pressing time is 6-8h.

7. The preparation method according to claim 1, characterized in that, In step S6, the annealing temperature is 1020-1100℃, and the holding time is 1.5-3h.

8. The preparation method according to claim 1, characterized in that, In step S9, the vacuum low-temperature heat treatment temperature is 300-400℃, and the holding time is 0.5-1h.

9. The preparation method according to claim 1, characterized in that, In step S10, the polishing time is 2-10 minutes.

10. A Co-Cr-Mo high-temperature alloy welding wire, characterized in that, The preparation method described in any one of claims 1-9 is used to prepare the product, and its chemical composition by weight percentage is as follows: Cr: 16.5-18.5%, Mo: 27.0-30.0%, Si: 3.0-3.8%, with the balance being Co and unavoidable impurities.

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