Preparation method of high-strength cobalt-based alloy wire

Abstract

The invention belongs to the technical field of cobalt-based alloy material processing, and relates to a preparation method of a high-strength cobalt-based alloy wire, in particular to a cold processing method of the high-strength cobalt-based alloy wire. According to the cold drawing method, the pass deformation is controlled to be 8%-16%, the heating number deformation is controlled to be 35%-60%, the specific heat treatment mode and the cold drawing die are matched, the whole-process cold drawing of the cobalt-based alloy wire with the diameter being 3.0 mm-0. 2 mm is achieved, the drawing speed reaches 10-35 m / min, the prepared cobalt-based alloy wire is high in strength, good in metallographic structure and high in uniformity, and the yield reaches 60% or above. According to the cold drawing production process, the problems that the cobalt-based high-temperature alloy is poor in plasticity and difficult to deform are solved, and meanwhile, the strength of the cobalt-based high-temperature alloy is improved along with conversion of a gamma phase into an epsilon phase in the drawing process.

Description

Technical Field

[0001] The invention belongs to the technical field of cobalt-based alloy material processing, and relates to a preparation method of a high-strength cobalt-based alloy wire, and specifically relates to a cold processing method of a high-strength cobalt-based alloy wire. Background Art

[0002] Cobalt-based superalloy is a hard alloy that is resistant to various types of wear and corrosion and has high strength. Cobalt-based superalloy is an alloy with cobalt as the main component and contains a considerable amount of chromium, tungsten, nickel and a small amount of other elements. Wires of about φ0.2mm are mainly used as raw materials for the preparation of medical cables and have high strength and corrosion resistance. The plasticity and toughness of cobalt-based superalloy materials on the market are not ideal, and cracks are prone to occur during processing. Therefore, how to improve the plasticity and toughness of the material while maintaining the high strength level of the material and process the material into wires of about φ0.2mm has become a technical key. Summary of the invention

[0003] The present invention provides a method for preparing high-strength cobalt-based alloy wire, which is used to solve the technical problem that cobalt-based high-temperature alloy wires are difficult to cold-draw due to poor plasticity and difficult deformation during wire drawing, and at the same time improve the tensile strength of cobalt-based alloy wires. The present invention provides a method for preparing φ3.0mm-φ0.2mm cobalt-based high-temperature alloy cold-drawn wires, and the specific scheme is as follows:

[0004] A method for preparing high-strength cobalt-based alloy wire is characterized in that: cobalt-based alloy wire raw materials are taken and cold-drawn in 4 to 10 batches, each batch needs to be heat-treated before cold-drawing, and the last batch is surface-treated after cold-drawing to obtain finished wires; the cold-drawing has 4 to 10 drawing batches, 2 to 6 passes per batch, 8 to 16% deformation per pass, and 35 to 60% deformation per fire per batch.

[0005] Furthermore, the mass percentages of the components of the cobalt-based alloy wire raw material are Cr: 18.0-22.0%, W: 14.0-17.0%, Ni: 8.0-12.0%, C: 0-0.15%, Fe: 1.0-3.5%, Si: 0-0.45%, Mn: 1.0-2.5%, P: 0-0.04%, and the remainder is Co, and the diameter of the wire raw material is 2.5-3 mm.

[0006] Furthermore, the heat treatment process is one of the following two situations:

[0007] A: Atmospheric annealing: annealing temperature is 1150℃~1250℃, holding time is 30~90min, then water quenching to room temperature;

[0008] B: Current online annealing: The current is set to 25-50A, the annealing time is 5-20s, and then water quenched to room temperature.

[0009] The current online annealing process is to let the wire pass through two charged conductive wheels with a distance of 1.5m. The time from any point on the wire entering the first conductive wheel to leaving the second conductive wheel is 5 to 20 seconds (ie, the annealing time is 5 to 20 seconds).

[0010] Furthermore, when the target diameter of the wire is above 0.8 mm, method A is used for heat treatment; when the target diameter of the wire is below 0.8 mm, method B is used for heat treatment; when the target diameter is 0.8 mm, either method A or method B can be used for heat treatment.

[0011] Furthermore, in the cold drawing, the drawing speed is 10-35 m / min, and the deformation amount of each pass in each batch is the same or similar (the difference between the maximum and minimum deformation amounts of each pass is ≤1%).

[0012] Furthermore, the surface treatment process is to electropolish the drawn wire.

[0013] Furthermore, in the electrolytic polishing, the electrolyte is a chromium trioxide aqueous solution with a mass fraction of 9 to 12%, and the current density is 0.2 to 1.5 A / cm 2 , the voltage is set to 40~60V, and the polishing time is 10~50s.

[0014] The electrolytic polishing process is as follows: the wire is used as the positive electrode and the titanium plate is used as the negative electrode. The wire passes through the electrolyte (the wire passes through the electrolyte). Any point on the wire takes 10 to 50 seconds from entering the electrolyte to leaving the electrolyte (i.e., the polishing time is 10 to 50 seconds).

[0015] A cobalt-based alloy wire prepared according to the above-mentioned preparation method is characterized in that the wire diameter is 0.2-0.8 mm and the grain size is 9-12 grades.

[0016] Advantages and beneficial effects of the present invention

[0017] 1. The cobalt-based alloy wire prepared by the process of the present invention has high strength, good metallographic structure, high uniformity, and a yield rate of more than 60%.

[0018] 2. The cold drawing process of the present invention adopts a high temperature treatment of 1150-1250°C and then water quenching to form a γ phase, which is a soft phase, and overcomes the problems of poor plasticity and difficult deformation of cobalt-based high-temperature alloys.

[0019] 3. The cobalt-based alloy wire prepared by the process of the present invention has fine grains, uniform structure, and high work hardening rate of the cobalt-based alloy. During the drawing process, the γ phase is transformed into the ε phase, which is a hard phase, thereby improving the tensile strength of the cobalt-based high-temperature alloy wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The equilibrium phase diagram of cobalt-based alloy

[0021] Figure 2 Metallographic diagram of cobalt-based alloy wire φ0.2mm

[0022] Figure 3 This is a photo of the bright surface of a cobalt-based alloy wire φ0.2mm DETAILED DESCRIPTION

[0023] The chemical composition of the wire raw material processed by the cobalt-based high-temperature alloy wire preparation process of the present invention is as follows by mass percentage: Cr: 20.0%, W: 15.0%, Ni: 10.0%, C: 0.06%, Fe: 2.0%, Si: 0.2%, Mn: 1.5%, P: 0.02%, and the balance is Co.

[0024] The drawing equipment used in the present invention is a non-slip drawing machine. The wire drawing unit consists of a wire-releasing part, a drawing part and a wire-receiving part. The drawing part uses an eye die, a drive and a tension rod as a drawing unit. Each independent driving wheel is strictly synchronized with the wire drawing speed. No sliding or friction occurs between the wire and the driving wheel, thereby realizing non-slip drawing.

[0025] During the processing of the cobalt-based high-temperature alloy wire of the present invention, annealing is performed at 1150°C-1200°C in the atmosphere and quenched in water to form a γ phase (such as Figure 1 ), γ phase is a soft phase and easy to draw. During the cold drawing process, the γ phase transforms into the ε phase, which is a hard phase, and the obtained wire has high tensile strength.

[0026] Example 1

[0027] (1) Wire preparation: Cobalt-based high-temperature alloy ingots are prepared by vacuum induction melting + gas shielded electroslag remelting. The smelted ingots are forged, rolled, peeled and hot drawn to obtain cobalt-based high-temperature alloy discs. The discs are rounded and peeled to obtain φ2.75 mm cobalt-based high-temperature alloy wire raw materials.

[0028] (2) Heat treatment: The cobalt-based high-temperature alloy wire material is placed in an annealing furnace for atmospheric annealing. The temperature is raised to 1200° C., kept at this temperature for 60 min, and then quenched in water to room temperature.

[0029] (3) Cold drawing: The heat-treated cobalt-based high-temperature alloy wire is cold drawn in 4 batches. Each batch has 4 cold drawing passes. The deformation of each pass is 14-15%. The total deformation of each batch (i.e., the deformation after fire) is 35%-60%, which is 46% here. The drawing speed is 10 m / min. Heat treatment is required before each batch of cold drawing process.

[0030] The heat treatment process is as follows: the cobalt-based high-temperature alloy wire obtained after the previous batch of cold drawing process is placed in an annealing furnace, heated to 1200°C, annealed in the atmosphere, kept warm for 60 minutes, and quenched in water to room temperature.

[0031] After 4 batches of cold drawing, the φ2.75mm wire material is obtained into φ0.8mm wire. The specific process is shown in Table 1 to Table 4. In the drawing size column in the table, the first number of each row of data indicates the wire diameter before the drawing, and the second number indicates the diameter after the drawing.

[0032] Table 1 First batch drawing

[0033]

[0034] Table 2 The second batch of drawing

[0035]

[0036] Table 3 The third batch of drawing

[0037]

[0038] Table 4 The fourth batch of drawing

[0039]

[0040] (4) Heat treatment: The φ0.8 mm wire obtained in step (3) is peeled to remove surface defects to obtain a φ0.753 mm wire, and then subjected to current online annealing pre-oxidation, that is, the wire is passed through two charged conductive wheels with a distance of 1.5 m. The time from any point on the wire entering the first conductive wheel to leaving the second conductive wheel is 10 s (i.e., the annealing time is 10 s). The online current of the wire is designed according to the resistivity of the wire. The current is 25-50 A, and is 30 A here. The wire after current annealing is bright red. The wire coming out of the second conductive wheel is immediately sprayed with water and quenched to room temperature.

[0041] (5) Cold drawing: The heat-treated φ0.753 mm wire is cold drawn in 4 batches, each batch has 5 cold drawing passes, each batch has a pass deformation of 12-13%, and each batch has a total deformation (i.e., fire deformation) of 40%-60%, which is 45-50% here. The drawing speed is 15 m / min. After 5-7 batches of cold drawing process, heat treatment is required before the next batch of cold drawing is carried out;

[0042] The heat treatment process is: current online annealing, that is, let the wire pass through two charged conductive wheels with a distance of 1.5m. The time from any point on the wire entering the first conductive wheel to leaving the second conductive wheel is 10s (that is, the annealing time is 10s). The online current of the wire is designed according to the resistivity of the wire. The current is 30A. The wire after current annealing is bright red. The wire coming out of the second conductive wheel is immediately sprayed with water and quenched to room temperature.

[0043] After 4 batches of cold drawing, the φ0.753mm wire was obtained into a φ0.2mm wire, and then the surface of the wire was treated by electrolytic polishing. The wire was used as the positive electrode, the titanium plate was used as the negative electrode, and the electrolyte was a chromium trioxide aqueous solution (mass fraction was 9%). The wire passed through the electrolyte (the wire passed through the electrolyte). Any point on the wire took 30 seconds from entering the electrolyte to leaving the electrolyte (i.e., the polishing time was 30 seconds), and the current density was 0.2-1.5A / cm 2 , here is 1A / cm 2 , the voltage is set to 40-60 V, here it is 50 V. The specific drawing process is shown in Table 5-Table 8.

[0044] Table 5 The fifth batch of drawing

[0045]

[0046]

[0047] Table 6 Drawing of the sixth batch

[0048]

[0049] Table 7 The seventh batch of drawing

[0050]

[0051] Table 8 The eighth batch of drawing

[0052]

[0053] The cobalt-based alloy wire with a diameter of φ0.2 mm prepared in this embodiment and the commercially available imported cobalt-based alloy wire with a diameter of φ0.2 mm were tested for mechanical properties according to standard GB / T 228.1-2021. The comparison results of tensile strength, yield strength, elongation and cross-sectional reduction are shown in Table 9. The cobalt-based alloy wire prepared in this embodiment has higher tensile strength and yield strength when the elongation and shrinkage are comparable to those of the imported wire. Figure 2 The grain size is 10.5. The more grains there are per unit volume, the more grain boundaries there are. Grain boundaries are areas where various distortions, defects and impurities gather inside the metal, which hinder the movement of dislocations, thereby increasing the deformation resistance and improving the strength of the material. Figure 3 The finished product is a φ0.2mm cobalt-based high-temperature alloy wire with a bright surface.

[0054] Table 9 Mechanical properties test of cobalt-based alloy

[0055]

[0056] The embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a high-strength cobalt-based alloy wire, characterized in that: Cobalt-based alloy wire raw materials are cold drawn in 4 to 10 batches, each batch needs to be heat treated before cold drawing, and the last batch is surface treated after cold drawing to obtain finished wires; the cold drawing has 4 to 10 drawing batches, 2 to 6 passes per batch, 8 to 16% deformation per pass, and 35 to 60% deformation per fire per batch.

2. The preparation method according to claim 1, characterized in that: The mass percentages of the components of the cobalt-based alloy wire raw material are Cr: 18.0-22.0%, W: 14.0-17.0%, Ni: 8.0-12.0%, C: 0-0.15%, Fe: 1.0-3.5%, Si: 0-0.45%, Mn: 1.0-2.5%, P: 0-0.04%, and the balance is Co. The diameter of the wire raw material is 2.5-3 mm.

3. The preparation method according to claim 1, characterized in that: The heat treatment process is one of the following two situations: A: Atmospheric annealing: annealing temperature is 1150℃~1250℃, holding time is 30~90min, then water quenching to room temperature; B: Current online annealing: The current is set to 25-50A, the annealing time is 5-20s, and then water quenched to room temperature.

4. The preparation method according to claim 3, characterized in that: If the target wire diameter is above 0.8mm, use method A for heat treatment; if the target wire diameter is below 0.8mm, use method B for heat treatment; if the target wire diameter is 0.8mm, either method A or B can be used for heat treatment.

5. The preparation method according to claim 1, characterized in that: The cold drawing has a drawing speed of 10-35 m / min, and the deformation amounts of each pass in each batch are the same or similar (the difference between the maximum and minimum deformation amounts of each pass is ≤1%).

6. The preparation method according to claim 1, characterized in that: The surface treatment process is to electropolish the drawn wire.

7. The preparation method according to claim 6, characterized in that: The electrolytic polishing, the electrolyte is a chromium trioxide aqueous solution with a mass fraction of 9-12%, and the current density is 0.2-1.5A / cm 2 , the voltage is set to 40~60V, and the polishing time is 10~50s.

8. A cobalt-based alloy wire prepared according to the preparation method according to any one of claims 1 to 7, characterized in that: The wire diameter is 0.2-0.8 mm, and the grain size is 9-12 grades.

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