Co-Cr-Mo welding wire and preparation method thereof

Abstract

The invention provides a Co-Cr-Mo welding wire and a preparation method thereof, and belongs to the field of metal materials. The Co-Cr-Mo welding wire comprises a metal powder core, and the metal powder core comprises, by mass, more than or equal to 20% of Cr + Mo, Si and Co-based powder; the surface of the metal powder core is coated with the cobalt-based welding strip, the cobalt-based welding strip comprises the following chemical components in percentage by mass: more than or equal to 90% of Co, less than or equal to 5% of Fe and less than or equal to 5% of trace elements, and the trace elements comprise one or more of Si, Mn, Al, B, W and rare earth elements. The corrosion resistance and the strength are enhanced through the elements such as Cr and Mo, the toughness is guaranteed through the high Co content and the elements such as Mn, and the strength, the toughness and the corrosion resistance of the welding wire are improved in a balanced mode through the synergistic effect of all the components.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal materials, in particular to a Co-Cr-Mo welding wire and a preparation method thereof. BACKGROUND

[0002] The Co-Cr-Mo welding wire is widely used in high-end fields such as medical implants, aerospace components and energy equipment due to its high-temperature-corrosion synergistic performance.

[0003] In these application scenarios, there are high requirements for the strength, toughness and corrosion resistance of the welding wire. For example, medical implants need to remain stable in the human body environment for a long time, which requires not only sufficient strength to withstand the load generated by human movement, but also good toughness to prevent fracture, and excellent corrosion resistance to avoid corrosion by human body fluids. The aerospace components also require the welding wire to endow the components with good comprehensive performance when working in an environment with high temperature, high pressure and corrosive medium. Therefore, how to realize the synergistic improvement of the strength, toughness and corrosion resistance of the welding wire is a technical problem to be solved at present. SUMMARY

[0004] The present application provides a Co-Cr-Mo welding wire and a preparation method thereof to solve the technical problem of how to realize the synergistic improvement of the strength, toughness and corrosion resistance of the welding wire.

[0005] In a first aspect, the embodiments of the present application provide a Co-Cr-Mo welding wire, which comprises:

[0006] A metal powder core, which comprises the following chemical components in mass fraction: Cr+Mo≥20%, Si, and Co-based powder.

[0007] A cobalt-based welding strip, which is coated on the surface of the metal powder core, and comprises the following chemical components in mass fraction: Co≥90%, Fe≤5%, and trace elements≤5%, the trace elements comprising one or more of Si, Mn, Al, B, W and rare earth elements.

[0008] Optionally, the sum of the content of Si in the metal powder core and the content of Si in the cobalt-based welding strip is≥3% in mass fraction.

[0009] The mass ratio of Cr to Mo in the metal powder core is 3:1-5:1.

[0010] Optionally, the diameter φ of the Co-Cr-Mo welding wire is 1.5mm-3.0mm, and the thickness of the cobalt-based welding strip is 0.1mm-0.4mm.

[0011] Optionally, the metal powder core has a particle size D50 of 20-50 mu m, and the volume of the metal powder core accounts for greater than or equal to 30% of the total volume of the Co-Cr-Mo welding wire.

[0012] Optionally, the Co-Cr-Mo welding wire has the following properties: elongation of 30-40%, tensile strength of 800-850 MPa, no rust after 300 hours of salt spray test, welding spatter rate of less than or equal to 3%, interface layer hardness HV of 450-500, and core hardness HV of 300-350.

[0013] In a second aspect, the embodiments of the present application provide a preparation method of the Co-Cr-Mo welding wire described in any one of the embodiments of the first aspect, and the method comprises the following steps:

[0014] obtaining a metal powder core and a cobalt-based welding strip with the chemical composition, respectively;

[0015] covering the cobalt-based welding strip on the surface of the metal powder core through a U-shaped forming die, and high-frequency induction welding a longitudinal seam under argon protection to obtain a coated welding strip;

[0016] performing multi-pass cold drawing on the coated welding strip to obtain a preformed wire;

[0017] performing vacuum sintering on the preformed wire to obtain a sintered wire;

[0018] performing straightening and fine grinding on the sintered wire to obtain the Co-Cr-Mo welding wire.

[0019] Optionally, the diameter of the preformed wire is 2.0-4.0 mm.

[0020] The surface roughness Ra of the Co-Cr-Mo welding wire is less than or equal to 0.8 mu m.

[0021] Optionally, the vacuum sintering of the preformed wire to obtain a sintered wire comprises the following steps:

[0022] firstly heating the preformed wire to a first set temperature and performing first heat preservation under a vacuum environment;

[0023] secondly heating the preformed wire with the first set temperature to a second set temperature and performing second heat preservation to form a gradient structure;

[0024] cooling the preformed wire with the second set temperature to a third set temperature, and then performing fast cooling to obtain a sintered wire.

[0025] Optionally, the first temperature increasing rate is 8-12 DEG C / min, the first set temperature is 780-820 DEG C, and the first holding time is 0.8-1.2 h.

[0026] The second set temperature is 1120-1180 DEG C, and the second holding time is 1.8-2.2 h.

[0027] The third set temperature is 150-250 DEG C.

[0028] The vacuum degree of the vacuum environment is less than or equal to 10 Pa.

[0029] Optionally, the deformation of each pass of the multi-pass cold drawing is 10-15%.

[0030] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages:

[0031] The Co-Cr-Mo welding wire provided by the embodiments of the present application comprises: a metal powder core, which comprises the following chemical components in mass fraction: Cr+Mo≥20%, Si, and Co-based powder; and a cobalt-based welding strip, which is coated on the surface of the metal powder core, and comprises the following chemical components in mass fraction: Co≥90%, Fe≤5%, and trace elements≤5%, wherein the trace elements comprise one or more of Si, Mn, Al, B, W, and rare earth elements.

[0032] The embodiments of the present application realize the synergistic improvement of the strength, toughness and corrosion resistance of the welding wire by designing the chemical components of the metal powder core and the cobalt-based welding strip, and the specific improvements are as follows:

[0033] In the metal powder core, Cr+Mo≥20%, Cr can form a dense oxide film to effectively block the corrosion medium from invading and significantly improve the corrosion resistance; Mo can enhance the pitting and crevice corrosion resistance of the material and further strengthen the corrosion resistance in cooperation with Cr. Meanwhile, Co≥90% in the cobalt-based welding strip, and Co itself has excellent corrosion resistance and can serve as a stable matrix to ensure the overall corrosion resistance of the welding wire.

[0034] Meanwhile, Cr and Mo in the metal powder core can improve the strength of the alloy matrix through solid solution strengthening; Fe≤5% in the cobalt-based welding strip, and the appropriate addition of Fe can improve the strength through solid solution strengthening while ensuring the toughness of the matrix; in addition, trace elements (such as W) can further enhance the hardness and strength of the material through dispersion strengthening to ensure that the welding wire has sufficient carrying capacity.

[0035] In addition, high Co content (≥90%) in the cobalt-based welding strip endows the material with excellent ductility and toughness, providing good deformation capacity for the welding wire and avoiding brittle fracture; trace elements (such as Mn) can improve the plasticity of the material, reduce stress concentration during welding or processing, and further ensure toughness. At the same time, the composition matching of the metal powder core and the welding strip (such as the synergistic effect of Si) can reduce welding defects and avoid the decrease of toughness caused by local brittle phase;

[0036] In summary, the balance of strength, toughness and corrosion resistance of the welding wire is improved by strengthening corrosion resistance and strength through elements such as Cr and Mo, and ensuring toughness through high Co content and elements such as Mn, and the synergistic effect of each component. BRIEF DESCRIPTION OF DRAWINGS

[0037] The accompanying drawings incorporated in and forming a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative labor.

[0039] Figure 1 A flowchart of a preparation method of a Co-Cr-Mo welding wire according to an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0041] The ranges described herein, such as ranges of values, ranges of ratios, and the like, are inclusive of all possible sub-ranges and individual numbers within that range, e.g. a range of "1 to 6" or "1-6" is inclusive of all sub-ranges between (and including) 1 and 6, e.g. 1 to 3, 2 to 5, etc. and individual numbers within that range, e.g. 1, 2, 3, 4, 5, 6. Unless otherwise specified, the terms "including", "comprising", and the like, as used herein, mean "including but not limited to" or "comprising but not limited to"; the terms "first", "second", and the like, as used herein, do not have any specific one-to-one correspondence with respect to order or relationship, and are merely used to distinguish one entity or operation from another; the term "and / or" as used herein refers to either or both of the items it connects; the terms "at least one", "one or more", and the like, as used herein, refer to any combination of one or more of the enumerated objects, including single or multiple objects; the proportional relationships, such as mass ratio, molar ratio, and the like, as described herein, are understood to be the corresponding relationship between the antecedent and the consequent in the order of description. The raw materials, reagents, instruments and equipment used herein can be purchased or prepared by existing methods.

[0042] The Co-Cr-Mo welding wire provided by the embodiments of the present application comprises:

[0043] A metal powder core, which comprises, in mass fraction, the following chemical components: Cr+Mo≥20%, Si, and Co-based powder;

[0044] A cobalt-based welding strip, which is coated on the surface of the metal powder core, and comprises, in mass fraction, the following chemical components: Co≥90%, Fe≤5%, and trace elements≤5%, the trace elements comprising one or more of Si, Mn, Al, B, W, and rare earth elements.

[0045] In one aspect, the embodiments of the present application rationally design the chemical components of the metal powder core. Cr and Mo are key alloying elements, which can significantly improve the high-temperature strength, corrosion resistance, and oxidation resistance of the welding wire. For example, in a high-temperature service environment, such as gas turbine blade repair, Cr and Mo can form a dense oxide film, effectively preventing the erosion of the high-temperature gas to the substrate, and improving the service life of the material. The addition of Si element helps to improve the fluidity of the molten pool, promote the deoxidation process, reduce welding defects, and improve the welding quality. A suitable Si content can reduce the surface tension of the molten pool, making the molten pool more easily spread and fill the weld, and at the same time, form oxides such as SiO2 by combining with oxygen, thereby reducing defects such as pores and inclusions in the weld.

[0046] In another aspect, the embodiments of the present application rationally design the chemical composition of the cobalt-based welding strip. A high content of Co endows the welding strip with excellent ductility, corrosion resistance and high-temperature strength, ensuring the formability of the welding wire during the processing and the stability in the use environment. For example, in the field of biological medicine, its good corrosion resistance can effectively avoid the corrosion of the implant in the human body environment, ensuring its long-term safety and reliability. The appropriate addition of Fe can adjust the strength and toughness of the material to some extent. Trace elements have different effects. Si in the welding strip cooperates with Si in the metal powder core to further improve the welding performance; Mn helps to improve the strength and toughness of the material; Al can improve the high-temperature oxidation resistance of the material, such as playing an important role in the repair of high-temperature service gas turbine blades; B can improve the fluidity of the molten pool, which is of great significance in the field of precise welding such as electronic packaging; W can improve the wear resistance of the material, which has important application in the field of chemical equipment manufacturing; rare earth elements can refine the grains and improve the comprehensive performance of the material.

[0047] In some embodiments, the sum of the content of Si in the metal powder core and the content of Si in the cobalt-based welding strip is ≥3% by mass fraction;

[0048] The mass ratio of Cr to Mo in the metal powder core is 3:1-5:1.

[0049] Limiting the sum of the content of Si in the metal powder core and the content of Si in the cobalt-based welding strip to ≥3% can ensure that there is enough Si to play a role in improving the fluidity of the molten pool and deoxidation during welding, thereby effectively improving the welding quality and reducing the occurrence of welding defects.

[0050] Limiting the mass ratio of Cr to Mo in the metal powder core to 3:1-5:1, Cr and Mo can synergize with each other and fully exert their advantages in improving high-temperature performance and corrosion resistance. For example, when the content of Cr is relatively high, a denser oxide film can be formed to improve the oxidation resistance; and the appropriate proportion of Mo helps to enhance the high-temperature strength and pitting corrosion resistance of the material, and the two cooperate with each other to make the welding wire exhibit excellent performance in harsh environments such as high temperature and corrosion. For example, the mass ratio of Cr to Mo in the metal powder core can be 3:1, 3.5:1, 4:1, 4.2:1, 4.5:1, 4.8:1, 5:1, etc.

[0051] In some embodiments, the diameter φ of the Co-Cr-Mo welding wire is 1.5-3.0 mm, and the thickness of the cobalt-based welding strip is 0.1-0.4 mm.

[0052] The diameter φ of the Co-Cr-Mo welding wire is limited to 1.5mm-3.0mm, which can meet the needs of various welding processes and application scenarios. For example, in the field of precision welding such as electronic packaging, a smaller diameter welding wire can be selected to achieve high-precision welding; while in the welding of large structural parts such as chemical equipment manufacturing, a larger diameter welding wire can improve the welding efficiency. For example, the diameter φ of the Co-Cr-Mo welding wire can be 1.5mm, 1.8mm, 2.0mm, 2.3mm, 2.5mm, 2.7mm, 3.0mm, etc.

[0053] The thickness of the cobalt-based welding strip is limited to 0.1mm-0.4mm, which is reasonably adjusted according to the diameter of the welding wire to ensure that the welding wire has good structural stability and processing performance. Thinner welding strips are suitable for small-diameter welding wires and can better achieve coating and processing; while thicker welding strips are suitable for large-diameter welding wires and provide sufficient strength and protection. For example, the thickness of the cobalt-based welding strip can be 0.1mm, 0.15mm, 0.2mm, 0.25mm, 0.3mm, 0.35mm, 0.4mm, etc.

[0054] In some embodiments, the particle size D50 of the metal powder core is 20μm-50μm, and the volume ratio of the metal powder core to the total volume of the Co-Cr-Mo welding wire is ≥30%.

[0055] The particle size D50 of the metal powder core is limited to 20μm-50μm, which can ensure the uniformity of the metal powder core during mixing and processing, and is beneficial to improve the consistency and stability of the composition of the welding wire. For example, the particle size D50 of the metal powder core can be 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, etc.

[0056] The volume ratio of the metal powder core to the total volume of the Co-Cr-Mo welding wire is ≥30%, which can fully play the role of alloying elements in the metal powder core and improve the overall performance of the welding wire. For example, in high-temperature service welding wire, a higher powder core ratio can allow more Cr, Mo and other elements to participate in the improvement of high-temperature performance, enhancing the oxidation resistance and creep resistance of the welding wire in high-temperature environments.

[0057] In some embodiments, the Co-Cr-Mo welding wire satisfies the following performance: elongation 30%-40%, tensile strength 800MPa-850MPa, no rust after 300h salt spray test, welding spatter rate ≤3%, interface layer hardness HV 450-500, core hardness HV 300-350.

[0058] The Co-Cr-Mo welding wire of the embodiments of the present application satisfies the following performance:

[0059] The elongation is 30% to 40%, and the higher elongation can make the welding wire better adapt to deformation during processing and welding, and is not easy to break, thereby improving the reliability of processing and welding; for example, the elongation of the Co-Cr-Mo welding wire can be 30%, 32%, 34%, 35%, 36%, 37%, 39%, 40%, etc.

[0060] The tensile strength is 800 MPa to 850 MPa, which ensures that the welded joint has sufficient strength and can withstand a certain load; for example, the tensile strength of the Co-Cr-Mo welding wire can be 800 MPa, 810 MPa, 820 MPa, 825 MPa, 830 MPa, 840 MPa, 845 MPa, 850 MPa, etc.

[0061] The salt spray test is 300h without rust, which indicates that the welding wire has excellent corrosion resistance and can maintain good performance in humid, corrosive and other harsh environments, and is suitable for marine engineering, chemical equipment and other fields;

[0062] The welding spatter rate is less than or equal to 3%, and the low welding spatter rate not only can save welding materials and reduce costs, but also can improve the quality and appearance of the welded joint and reduce subsequent processing procedures.

[0063] The interface layer hardness HV is 450 to 500, and the core hardness HV is 300 to 350, and such a gradient hardness structure helps to improve the interface bonding strength, so that the welding wire can better transmit stress during welding, while ensuring that the core has certain toughness, improving the uniformity of the welding wire cladding, and reducing welding spatter.

[0064] Figure 1 A flowchart of a preparation method of a Co-Cr-Mo welding wire provided in the embodiments of the present application is shown.

[0065] As shown in Figure 1 The embodiments of the present application provide a preparation method of the Co-Cr-Mo welding wire described in any one of the above embodiments, and the method comprises:

[0066] S1, respectively obtaining a metal powder core and a cobalt-based welding strip with the chemical composition;

[0067] In some embodiments, the preparation method of the metal powder core comprises: mixing metal powder raw materials according to a designed proportion, and adopting a planetary ball mill (rotation speed 300 rpm, time 4h) to obtain uniform powder (particle size D50=20-50μm).

[0068] S2, wrapping the cobalt-based welding strip on the surface of the metal powder core through a U-shaped forming die, and high-frequency induction welding a longitudinal seam under argon protection to obtain a wrapped welding strip;

[0069] It should be noted that the S2 step is specifically: first, the cobalt-based welding strip is cut into a strip with a width of 5-15 mm, and a suitable width can ensure good adhesion and processability when the metal powder core is wrapped. Then, the strip is bent into a U shape through a U-shaped forming die, so that it can tightly wrap the metal powder core. High-frequency induction welding is performed on the longitudinal seam under argon protection. The role of argon is to exclude air in the welding area to prevent oxidation and ensure welding quality. High-frequency induction welding can quickly heat the weld, forming a good metallurgical bond between the welding strip and the powder core, while reducing the range of the heat-affected zone and avoiding adverse effects on material performance.

[0070] S3, the coated welding strip is subjected to multi-pass cold drawing to obtain a preformed wire;

[0071] In some embodiments, the deformation amount of each pass of the multi-pass cold drawing is 10%-15%.

[0072] In some embodiments, the diameter φ of the preformed wire is 2.0 mm-4.0 mm.

[0073] Multi-pass cold drawing is an important process for improving the density and improving the performance of the welding wire. In this process, the deformation amount of each pass is controlled at 10%-15%, and the appropriate deformation amount can ensure the plasticity of the material during processing, and gradually refine and densify the structure. Through multi-pass drawing, the size of the coated welding strip gradually decreases, and finally a preformed wire with a preliminary diameter φ of 2.0 mm-4.0 mm is obtained. This diameter range provides a suitable blank for subsequent vacuum sintering and further processing. For example, the deformation amount of each pass of the multi-pass cold drawing can be 10%, 11%, 11.5%, 12%, 13%, 13.5%, 14%, 15%, etc.; the diameter φ of the preformed wire can be 2.0 mm, 2.3 mm, 2.6 mm, 2.9 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4.0 mm, etc.

[0074] S4, vacuum sintering the preformed wire to obtain a sintered wire;

[0075] In some embodiments, the vacuum sintering of the preformed wire to obtain a sintered wire comprises:

[0076] In a vacuum environment, the preformed wire is first heated to a first set temperature and is subjected to first heat preservation;

[0077] The preformed wire with the first set temperature is secondly heated to a second set temperature and is subjected to second heat preservation to form a gradient structure;

[0078] The preformed wire with the second set temperature is cooled to a third set temperature, and then is subjected to rapid cooling to obtain a sintered wire.

[0079] In some embodiments, the first temperature increasing rate is 8-12℃ / min, the first set temperature is 780-820℃, and the first holding time is 0.8-1.2h;

[0080] The second set temperature is 1120-1180℃, and the second holding time is 1.8-2.2h;

[0081] The third set temperature is 150-250℃;

[0082] The vacuum degree of the vacuum environment is ≤10Pa.

[0083] The preform wire is subjected to segmented temperature increasing sintering under a vacuum environment.

[0084] First, the first temperature increasing is at a rate of 8-12℃ / min to 780-820℃, and the first holding time is 0.8-1.2h. The main role of this stage is to promote the removal of impurities such as gas and organic matter in the powder core, purify the internal environment of the material, and create good conditions for the subsequent sintering process; for example, the first temperature increasing rate can be 8℃ / min, 8.5℃ / min, 9℃ / min, 10℃ / min, 10.5℃ / min, 11℃ / min, 11.5℃ / min, 12℃ / min, etc.; the first set temperature can be 780℃, 785℃, 790℃, 800℃, 805℃, 810℃, 815℃, 820℃, etc.; and the first holding time can be 0.8h, 0.85h, 0.9h, 1.0h, 1.05h, 1.1h, 1.15h, 1.2h, etc.

[0085] Then, the preform wire with the first set temperature is secondly increased to 1120-1180℃, and the second holding time is 1.8-2.2h. In this temperature range and holding time, Co, Cr, Mo and other elements can be fully diffused to form a Co-Cr-Mo solid solution, and a gradient structure can be formed to improve the interface bonding strength, improve the uniformity of the welding wire cladding, and reduce the welding spatter; for example, the second set temperature can be 1120℃, 1130℃, 1140℃, 1150℃, 1160℃, 1170℃, 1175℃, 1180℃, etc.; and the second holding time can be 1.8h, 1.85h, 1.9h, 2.0h, 2.05h, 2.1h, 2.15h, 2.2h, etc.

[0086] Finally, the preformed wire with the second set temperature is cooled to 150-250℃, and then fast cooling is performed to obtain the sintered wire. In the mode of cooling to a certain temperature in the furnace and then air cooling, the embrittlement phenomenon of the outer cobalt layer due to too fast cooling speed can be avoided, and the comprehensive performance of the material is ensured. For example, the third set temperature can be 180℃, 185℃, 190℃, 200℃, 205℃, 210℃, 215℃, 220℃, etc.

[0087] The entire vacuum sintering process is carried out in an environment with a vacuum degree of ≤10 Pa, and a low vacuum degree can effectively avoid oxidation, minimize the total oxygen content, and reduce defects such as thermal stress cracking.

[0088] S5, straightening and fine grinding the sintered wire to obtain the Co-Cr-Mo welding wire.

[0089] In some embodiments, the surface roughness Ra of the Co-Cr-Mo welding wire is ≤0.8 μm.

[0090] The wire after vacuum sintering may have some bending and surface unevenness. Through the multi-roller straightening machine, the residual stress generated during drawing and sintering is eliminated, so that the wire meets the straightness requirement. Then, the straightened wire is fine ground by a centerless grinding machine to the target diameter, with an accuracy control of ±0.02 mm, and the surface roughness Ra is ≤0.8 μm. High-precision diameter control and good surface quality are of great significance to the stability of wire feeding and welding quality during welding, and can ensure the uniformity and consistency of the welding process.

[0091] The preparation method of the Co-Cr-Mo welding wire produces the above-mentioned Co-Cr-Mo welding wire. The chemical composition and structure of the Co-Cr-Mo welding wire produced by the preparation method of the Co-Cr-Mo welding wire can refer to the above-mentioned embodiments. Since the preparation method of the Co-Cr-Mo welding wire adopts part or all of the technical solutions of the Co-Cr-Mo welding wire embodiments, it at least has all the beneficial effects brought by the technical solutions of the Co-Cr-Mo welding wire embodiments, which will not be repeated here.

[0092] Through material composition design, structure parameter optimization and preparation process innovation, the application realizes the synergistic improvement of the strength, toughness and corrosion resistance of the Co-Cr-Mo welding wire, and the specific path is as follows:

[0093] (1) Component design synergy: The components of the metal powder core and the cobalt-based welding strip are matched. The mass ratio of Cr to Mo in the metal powder core is controlled to be 3:1-5:1, and the content of Cr+Mo is greater than or equal to 20%. Cr forms a dense oxide film to improve corrosion resistance and oxidation resistance. Mo enhances high-temperature strength and pitting resistance. The two synergistically strengthen corrosion resistance and strength. At the same time, the content of Co in the cobalt-based welding strip is greater than or equal to 90%, which ensures excellent ductility and matrix stability. The content of Fe is less than or equal to 5% to adjust the strength and toughness. Trace elements (such as Al to improve high-temperature oxidation resistance, W to improve wear resistance, and rare earth to refine grains) further optimize the comprehensive performance. In addition, the sum of the Si contents in the metal powder core and the welding strip is greater than or equal to 3%. This improves the fluidity of the molten pool to reduce welding defects, and reduces the adverse effects of impurities on performance through deoxidation, thereby indirectly improving strength and corrosion resistance.

[0094] (2) Precise control of structural parameters: Optimization of gradient structure and powder core ratio. The volume ratio of the metal powder core is greater than or equal to 30%, which ensures that the strengthening elements such as Cr and Mo fully play their roles. At the same time, the powder core particle size D50 is controlled to be 20-50 μm to ensure component uniformity and avoid local performance fluctuations. At the same time, the gradient structure formed after vacuum sintering is "interface layer hardness HV450-500, core HV300-350". The high hardness of the interface layer improves the bonding strength and wear resistance, and the lower hardness of the core ensures the toughness, thereby achieving a balance between strength and toughness. In addition, the matching of the welding wire diameter of 1.5-3.0 mm and the welding strip thickness of 0.1-0.4 mm ensures the structural stability, reduces stress concentration through reasonable coating ratio, and improves processing toughness. The surface roughness Ra is less than or equal to 0.8 μm after precision grinding, which reduces surface defects, reduces the risk of corrosion medium invasion, and enhances corrosion resistance.

[0095] (3) Synergistic strengthening of preparation process: Powder core preparation and coating forming. Planetary ball milling (300 rpm, 4 h) is used to obtain uniform powder (D50=20-50 μm) to ensure component consistency. High-frequency induction welding is used to form a longitudinal seam under argon protection to avoid oxidation and pollution, ensure the close combination of the welding strip and the powder core, and reduce the weakening of interface defects on strength and corrosion resistance. At the same time, the process of cold drawing and vacuum sintering is used. Multi-pass cold drawing (deformation of 10%-15% per pass) improves the density and strength through work hardening, while the deformation amount is controlled to avoid excessive embrittlement and retain toughness. In addition, the material is purified by removing impurities at 800°C in a vacuum sintering furnace (≤10 Pa), and the Co-Cr-Mo solid solution is promoted to form at 1150°C, thereby enhancing the interface bonding and component uniformity. After cooling to 200°C in the furnace, the material is air-cooled to avoid cobalt embrittlement and ensure toughness. Post-processing performance optimization, multi-roll straightening to eliminate residual stress, reduces the risk of stress corrosion; precision grinding controls the diameter accuracy (±0.02 mm) and surface roughness, reduces stress concentration and corrosion initiation points, and further improves corrosion resistance and fatigue strength.

[0096] (4) Synergistic realization of performance indicators: Through the above design, the welding wire finally realizes: tensile strength 800-850 MPa (high strength), elongation 30%-40% (high toughness), salt spray test 300h without rust (high corrosion resistance), and welding spatter rate ≤3%, verifying the synergistic promotion effect of strength, toughness and corrosion resistance.

[0097] Therefore, the application significantly improves the processing performance and composition uniformity of the welding wire by coating the Cr-Mo metal powder core with a cobalt-based strip and combining a vacuum sintering process. Through material design and process optimization, the method realizes the synergistic promotion of the strength, toughness and corrosion resistance of the welding wire.

[0098] The application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the application and not to limit the scope of the application. The experimental methods in the following examples are not specified unless the industry standard is specified. If there is no corresponding industry standard, the general international standard, conventional conditions, or the conditions recommended by the manufacturer are used.

[0099] Example 1: High-temperature service welding wire (repair of gas turbine blade)

[0100] Objective: Optimize high-temperature strength and oxidation resistance to meet the repair needs of gas turbine blades under extreme conditions such as high temperature, high pressure, and high speed. During operation, the gas turbine blade not only has to withstand the scouring of high-temperature gas, but also has to withstand huge mechanical stress, so the high-temperature performance requirements for the repair material are extremely high.

[0101] This embodiment provides a Co-Cr-Mo welding wire, which comprises a metal powder core and a cobalt-based welding strip, specifically as follows:

[0102] The metal powder core comprises the following chemical components in mass fraction: Cr=22%, Mo=8%, Si=3.5%, and the balance is Co-based powder (the mass ratio of Cr to Mo is 2.75:1);

[0103] The cobalt-based welding strip is coated on the surface of the metal powder core and comprises the following chemical components in mass fraction: Co=96%, Fe=3.5%, and Al=0.5% (Al is a trace element for improving high-temperature oxidation resistance); the thickness of the cobalt-based welding strip is 0.25mm;

[0104] Based on the above Co-Cr-Mo welding wire, this embodiment simultaneously provides a preparation method of the above Co-Cr-Mo welding wire, comprising the following steps:

[0105] S11, respectively obtain a metal powder core and a cobalt-based welding strip with the above chemical components;

[0106] S21, the cobalt-based welding strip is wrapped on the surface of the metal powder core by a U-shaped forming die, and a longitudinal seam is welded under high-frequency induction in an argon atmosphere to obtain a wrapped welding strip;

[0107] S31, the wrapped welding strip is subjected to multi-pass cold drawing (deformation of 12% per pass) to obtain a pre-formed wire;

[0108] S41, the pre-formed wire is subjected to vacuum sintering (vacuum degree ≤10 Pa) to obtain a sintered wire; the vacuum sintering comprises: in a vacuum environment, the pre-formed wire is first heated to 800°C at a rate of 10°C / min and is subjected to first heat preservation for 1 h; the pre-formed wire with 800°C is second heated to 1150°C and is subjected to second heat preservation for 2 h to form a gradient structure; after the pre-formed wire with 1150°C is cooled to 150°C in the furnace, argon is filled for fast cooling to obtain the sintered wire;

[0109] S51, the sintered wire is subjected to straightening and fine grinding to obtain the Co-Cr-Mo welding wire with a diameter of 2.0 mm and a surface roughness Ra of 0.2 μm.

[0110] The performance of the Co-Cr-Mo welding wire is as follows:

[0111] The 800°C yield strength is 320 MPa;

[0112] The 1000 h cyclic oxidation weight gain is 0.15 mg / cm 2 (50% better than traditional welding wire);

[0113] The weld impact toughness is 45 J (Charpy V-notch);

[0114] The welding spatter rate is 0.5%.

[0115] Example 2: biomedical welding wire (orthopedic implant connector)

[0116] Objective: to improve biocompatibility and corrosion resistance to ensure the long-term safety and stability of orthopedic implants in the human body environment. Orthopedic implants need to be in long-term contact with human tissues, so the requirements for biocompatibility and corrosion resistance are extremely strict.

[0117] Example 2

[0118] This embodiment provides a Co-Cr-Mo welding wire, which comprises a metal powder core and a cobalt-based welding strip, and specifically as follows:

[0119] The metal powder core comprises the following chemical components in mass fraction: Cr = 20%, Mo = 6%, Si = 4%, and the balance is Co-based powder (containing 0.5% Y2O3 nanoparticles).

[0120] The cobalt-based welding strip is coated on the surface of the metal powder core, and contains the following chemical components in mass fraction: Co = 95%, Fe = 4%, and Mn = 1% (Mn is a trace element for enhancing ductility); the thickness of the cobalt-based welding strip is 0.15 mm;

[0121] Based on the above-mentioned Co-Cr-Mo welding wire, the embodiment simultaneously provides a preparation method of the above-mentioned Co-Cr-Mo welding wire, comprising the following steps:

[0122] S12, respectively obtaining a metal powder core and a cobalt-based welding strip with the above-mentioned chemical components;

[0123] S22, coating the cobalt-based welding strip on the surface of the metal powder core through a U-shaped forming die, and high-frequency induction welding a longitudinal seam under argon protection to obtain a coated welding strip;

[0124] S32, performing multi-pass cold drawing (deformation of each pass is 11%) on the coated welding strip to obtain a preformed wire (diameter φ is 3 mm);

[0125] S42, performing vacuum sintering (vacuum degree is ≤10 Pa) on the preformed wire to obtain a sintered wire; the vacuum sintering comprises: first heating the preformed wire to 800°C at a rate of 9°C / min in a vacuum environment, and performing first heat preservation for 1.2 h; second heating the preformed wire with the first set temperature to 1130°C, and performing second heat preservation for 1.9 h to form a gradient structure; cooling the preformed wire with the second set temperature to 250°C and then air cooling to obtain the sintered wire;

[0126] S52, performing pickling (using HNO3+HF mixed solution) on the sintered wire to remove the surface oxide layer, and then performing straightening and fine grinding to obtain the Co-Cr-Mo welding wire with a diameter of 1.5 mm and a surface roughness Ra≤0.8 μm.

[0127] The performance of the Co-Cr-Mo welding wire is as follows:

[0128] No rust for 500 h of salt spray test;

[0129] Cell toxicity (ISO10993-5) is 0 level;

[0130] Welding spatter rate is 2.3% (traditional welding wire is 8%).

[0131] Example 3: Ultra-thin diameter welding wire (electronic packaging application)

[0132] Objective: To achieve precise welding of small-diameter welding wire and meet the demand for high-precision and high-reliability welding in the field of electronic packaging. In electronic packaging, it is necessary to accurately connect tiny electronic components, and the diameter and welding precision of the welding wire are extremely high.

[0133] Embodiment 3

[0134] This embodiment provides a Co-Cr-Mo welding wire, which comprises a metal powder core and a cobalt-based welding strip, and specifically as follows:

[0135] The metal powder core comprises the following chemical components in mass fraction: Cr = 18%, Mo = 10%, Si = 3%, and the balance is Co-based powder (the mass ratio of Cr to Mo is 1.8:1);

[0136] The cobalt-based welding strip is coated on the surface of the metal powder core and comprises the following chemical components in mass fraction: Co = 97%, Fe = 2%, and B = 0.03% (B is a trace element for improving the fluidity of the molten pool); the thickness of the cobalt-based welding strip is 0.1 mm;

[0137] Based on the above Co-Cr-Mo welding wire, this embodiment simultaneously provides a preparation method of the above Co-Cr-Mo welding wire, which comprises the following steps:

[0138] S13, respectively obtaining a metal powder core and a cobalt-based welding strip with the above chemical components;

[0139] S23, coating the cobalt-based welding strip on the surface of the metal powder core through a U-shaped forming die, and high-frequency induction welding a longitudinal seam under the protection of argon to obtain a coated welding strip;

[0140] S33, performing multi-pass cold drawing (deformation amount of each pass is 12.1%, and total deformation amount is 85%) on the coated welding strip to obtain a preformed wire (diameter φ is 2.0 mm);

[0141] S43, performing vacuum sintering (vacuum degree is ≤10 Pa) on the preformed wire to obtain a sintered wire; the vacuum sintering comprises: first heating the preformed wire to 780℃ at a rate of 11℃ / min in a vacuum environment, and performing first heat preservation for 0.8 h; second heating the preformed wire with the first set temperature to 1120℃, and performing second heat preservation for 1.8 h to form a gradient structure; cooling the preformed wire with the second set temperature to 150-250℃ and then air cooling to obtain the sintered wire;

[0142] S53, annealing treatment (600℃ / 2h) is performed on the sintered wire to eliminate work hardening, followed by straightening and fine grinding, to obtain the Co-Cr-Mo welding wire with a diameter of 0.8mm and a surface roughness Ra of 0.2μm.

[0143] The performance of the Co-Cr-Mo welding wire is as follows:

[0144] The tensile strength is 820MPa;

[0145] The elongation is 38%;

[0146] The welding joint air tightness: helium leak rate <1×10 -9 Pa·m 3 / s.

[0147] Example 4: Low-cost welding wire (chemical equipment manufacturing)

[0148] Objective: Under the premise of meeting the basic performance requirements of welding wire for chemical equipment manufacturing, such as corrosion resistance, strength and welding stability, the performance and cost are balanced by optimizing the material composition (such as recycled cobalt powder) and adjusting the process parameters (such as reducing sintering energy consumption).

[0149] The embodiment provides a Co-Cr-Mo welding wire and a preparation method thereof, and the Co-Cr-Mo welding wire comprises a metal powder core and a cobalt-based welding strip, and specifically as follows:

[0150] The metal powder core comprises the following chemical components in mass fraction: Cr=20%, Mo=5%, Si=3%, and the balance is Co-based powder (containing 5% recycled cobalt powder);

[0151] The cobalt-based welding strip is coated on the surface of the metal powder core, and comprises the following chemical components in mass fraction: Co=94%, Fe=5%, and W=1% (W is a trace element for improving wear resistance); the thickness of the cobalt-based welding strip is 0.4mm;

[0152] Based on the Co-Cr-Mo welding wire, the embodiment simultaneously provides a preparation method of the Co-Cr-Mo welding wire, comprising the following steps:

[0153] S14, the metal powder core and the cobalt-based welding strip with the above chemical components are obtained respectively;

[0154] S24, the cobalt-based welding strip is coated on the surface of the metal powder core through a U-shaped forming die, and a longitudinal seam is welded under high-frequency induction in argon protection, to obtain a coated welding strip;

[0155] S34, the coated welding strip is subjected to multi-pass cold drawing (deformation amount of each pass is 14%), to obtain a preformed wire (diameter φ is 4.0mm);

[0156] S44, vacuum sintering (vacuum degree ≤ 10 Pa) is performed on the preformed wire to obtain a sintered wire; the vacuum sintering comprises: under a vacuum environment, first heating the preformed wire to 800 DEG C at a rate of 12 DEG C / min and performing first heat preservation for 1 h; second heating the preformed wire with 800 DEG C to 1100 DEG C and performing second heat preservation for 3 h to form a gradient structure (reducing energy consumption); after cooling the preformed wire with 1100 DEG C to 250 DEG C, air cooling is performed to obtain the sintered wire;

[0157] S54, straightening and fine grinding are performed on the sintered wire to obtain the Co-Cr-Mo welding wire with a diameter of 3.0 mm and a surface roughness Ra = 0.2 μm.

[0158] The performance of the Co-Cr-Mo welding wire is as follows:

[0159] The HCl corrosion resistance rate (60 DEG C) is 0.02 mm / a;

[0160] The cost is reduced by 18% compared with a new cobalt powder welding wire;

[0161] The hardness of the welded joint is HV320 (uniformity ± 5%).

[0162] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0163] (1) In the embodiments of the present application, the cobalt-based strip material is coated with Cr-Mo metal powder core, and the vacuum sintering process is combined to significantly improve the processing performance and composition uniformity of the welding wire. Through material design and process optimization, the strength, toughness and corrosion resistance of the welding wire are synergistically improved.

[0164] (2) In the embodiments of the present application, the cobalt strip composition and the powder core composition are matched and combined, and the corresponding preparation and processing parameters are combined. For different fields and scene applications, the super-high temperature oxidation resistance in the gas turbine field, the biocompatibility and low spatter rate in the medical field, the small-diameter precision welding in the electronic packaging, and the optimal cost performance and corrosion resistance performance can be realized by matching the appropriate proportion of returned material recycling. The elongation (A) of the prepared welding wire is 30% to 40%, the tensile strength is 800 to 850 (MPa), the corrosion resistance (salt spray test) is 300h without rust, and the welding spatter rate is less than 3%.

[0165] (3) In the embodiments of the present application, the cobalt strip is coated with the Cr-Mo powder core, and is drawn into a shape after vacuum sintering, which has processability and controllability of composition.

[0166] (4) In the embodiment of the present application, the parameters of the staged vacuum sintering are controlled to minimize the total oxygen and promote the diffusion of Cr / Mo to the cobalt matrix to form a gradient structure (interface layer hardness HV 450-500, core hardness HV 300-350), to improve the interface bonding strength and reduce the welding spatter rate.

[0167] The above description is merely that of the embodiments of the application, and enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application will not be limited to the embodiments shown herein but will be accorded the widest scope consistent with the principles and novel features described herein.

Claims

1. A Co-Cr-Mo welding wire, wherein the Co-Cr-Mo welding wire comprises: The metal powder core, by mass fraction, comprises the following chemical composition: Cr+Mo≥20%, Si, and Co-based powder; The cobalt-based solder ribbon is coated on the surface of the metal powder core. By mass fraction, the cobalt-based solder ribbon has the following chemical composition: Co≥90%, Fe≤5%, and trace elements≤5%, including one or more of Si, Mn, Al, B, W, and rare earth elements.

2. The Co-Cr-Mo welding wire according to claim 1, characterized in that, The sum of the Si content in the metal powder core and the Si content in the cobalt-based solder ribbon is ≥3% by mass fraction. The mass ratio of Cr to Mo in the metal powder core is 3:1 to 5:

1.

3. The Co-Cr-Mo welding wire according to claim 1, characterized in that, The diameter φ of the Co-Cr-Mo welding wire is 1.5mm to 3.0mm, and the thickness of the cobalt-based welding strip is 0.1mm to 0.4mm.

4. The Co-Cr-Mo welding wire according to claim 1, characterized in that, The particle size D50 of the metal powder core is 20μm to 50μm, and the volume of the metal powder core accounts for ≥30% of the total volume of the Co-Cr-Mo welding wire.

5. The Co-Cr-Mo welding wire according to claim 1, characterized in that, The Co-Cr-Mo welding wire meets the following performance requirements: elongation of 30% to 40%, tensile strength of 800 MPa to 850 MPa, no rust after 300 hours of salt spray testing, welding spatter rate ≤3%, interface layer hardness HV of 450 to 500, and core hardness HV of 300 to 350.

6. A method for preparing the Co-Cr-Mo welding wire according to any one of claims 1 to 5, the method comprising: Metal powder cores and cobalt-based solder strips with the aforementioned chemical composition were obtained respectively; The cobalt-based welding strip is coated onto the surface of the metal powder core using a U-shaped forming mold, and the longitudinal seam is welded by high-frequency induction welding under argon protection to obtain the coated welding strip. The coated welding strip is subjected to multiple cold drawing processes to obtain a pre-formed wire. The preformed filament is vacuum sintered to obtain sintered filament; The sintered wire is straightened and finely ground to obtain the Co-Cr-Mo welding wire.

7. The method according to claim 6, characterized in that, The diameter φ of the preformed filament is 2.0mm to 4.0mm; The surface roughness Ra of the Co-Cr-Mo welding wire is ≤0.8μm.

8. The method according to claim 6, characterized in that, The step of vacuum sintering the preformed filament to obtain sintered filament includes: In a vacuum environment, the preformed filament is first heated to a first set temperature and then kept warm for the first time. The preformed filament, which has a first set temperature, is heated to a second set temperature and then kept warm for a second time to form a gradient structure. The preformed filament with a second set temperature is cooled to a third set temperature and then rapidly cooled to obtain a sintered filament.

9. The method according to claim 8, characterized in that, The first heating rate is 8℃ / min to 12℃ / min, the first set temperature is 780℃ to 820℃, and the first holding time is 0.8h to 1.2h. The second set temperature is 1120℃~1180℃, and the second heat preservation time is 1.8h~2.2h; The third set temperature is 150℃~250℃; The vacuum level of the vacuum environment is ≤10Pa.

10. The method according to claim 6, characterized in that, The deformation amount per pass in the multi-pass cold drawing is 10% to 15%.

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