A method for producing a high-strength cobalt-based alloy wire

Abstract

The present application belongs to the technical field of cobalt-based alloy material processing, and relates to a preparation method of high-strength cobalt-based alloy wire, in particular to a cold processing method of high-strength cobalt-based alloy wire. The present application realizes the whole-process cold drawing of cobalt-based alloy wire φ3.0mm-φ0.2mm by controlling the pass deformation amount to be 8%-16%, the heat deformation amount to be 35%-60%, and cooperating with specific heat treatment mode and cold drawing die, the drawing speed reaches 10-35m / min, the prepared cobalt-based alloy wire has high strength, good metallographic structure, high uniformity, and the yield is up to more than 60%. The cold drawing production process of the present application overcomes the problems of poor plasticity and difficult deformation of cobalt-based high-temperature alloy, and the γ phase is transformed into ε phase during the drawing process, thereby improving the strength of the cobalt-based high-temperature alloy.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cobalt-based alloy material processing, and relates to a preparation method of high-strength cobalt-based alloy wire, in particular to a cold processing method of high-strength cobalt-based alloy wire. BACKGROUND

[0002] Cobalt-based high-temperature alloy is a hard alloy capable of resisting various types of wear and corrosion and having high strength. The cobalt-based high-temperature alloy is an alloy mainly composed of cobalt and containing a considerable amount of chromium, tungsten, nickel and a small amount of other elements. The wire with a diameter of about 0.2 mm is mainly used as a raw material for preparing medical cables and has high strength and corrosion resistance. At present, the plasticity and toughness of the cobalt-based high-temperature alloy material 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 and process the material into a wire with a diameter of about 0.2 mm becomes a technical key. SUMMARY

[0003] The application provides a preparation method of high-strength cobalt-based alloy wire to solve the technical problem that cobalt-based high-temperature alloy is difficult to be cold drawn due to poor plasticity and difficult deformation during wire drawing, and the tensile strength of the cobalt-based alloy wire is improved. The application provides a preparation method of cold drawing of cobalt-based high-temperature alloy with a diameter of 3.0 mm to 0.2 mm, and the specific scheme is as follows:

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

[0005] Further, the mass percentage of the components of the cobalt-based alloy wire raw materials is as follows: 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, and the diameter of the wire raw materials is 2.5-3 mm.

[0006] Further, the heat treatment process is one of the following two cases:

[0007] A: air annealing: the annealing temperature is 1150-1250℃, the holding time is 30-90 min, and then water quenching to room temperature;

[0008] B: Current on-line annealing: current is set to 25-50A, annealing time is 5-20s, and then water quenching to room temperature.

[0009] The current on-line annealing process is that the wire passes through two charged conductive wheels with a distance of 1.5m, and the time from entering the first conductive wheel to leaving the second conductive wheel at any point on the wire is 5-20s (i.e. annealing time 5-20s).

[0010] Further, the target diameter of the wire is above 0.8mm, and the heat treatment is performed in the mode A; the target diameter of the wire is below 0.8mm, and the heat treatment is performed in the mode B; and the target diameter is 0.8mm, and either the mode A or the mode B can be used.

[0011] Further, the cold drawing is performed at a speed of 10-35m / 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] Further, the surface treatment process is that the drawn wire is subjected to electrolytic polishing.

[0013] Further, the electrolytic polishing is performed by using a 9-12% mass fraction of chromium trioxide aqueous solution as the electrolyte, setting the current density to 0.2-1.5A / cm 2 , setting the voltage to 40-60V, and setting the polishing time to 10-50s.

[0014] The electrolytic polishing process is that the wire is used as the anode, a titanium plate is used as the cathode, the wire passes through (pierces through) the electrolyte, and the time from entering the electrolyte to leaving the electrolyte at any point on the wire is 10-50s (i.e. polishing time 10-50s).

[0015] A cobalt-based alloy wire prepared by the preparation method, characterized in that the diameter of the wire is 0.2-0.8mm, and the grain size is 9-12 levels.

[0016] Advantages and beneficial effects of the present application

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

[0018] 2. The cold drawing process of the present application uses high-temperature treatment at 1150-1250℃ followed by water quenching to form a gamma phase, which is a soft phase, and overcomes the problems of poor plasticity and difficult deformation of the cobalt-based high-temperature alloy.

[0019] 3、The cobalt-based alloy wire prepared by the process has fine grains, uniform structure, and high work hardening rate, and the gamma phase is converted into epsilon phase during the drawing process, the epsilon phase is a hard phase, and the tensile strength of the cobalt-based high-temperature alloy wire is improved. BRIEF DESCRIPTION OF DRAWINGS

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

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

[0022] Figure 3 Photo of bright surface of 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 application is as follows in terms of 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 by the application is a non-slip intermediate drawing machine, and the wire drawing unit is composed of a pay-off section, a drawing section and a take-up section. The drawing section adopts one eye die, one drive and one tension rod as one drawing unit. Each independent drive wheel is strictly synchronized with the wire drawing speed, and no sliding and friction occurs between the wire and the drive wheel, so that non-slip drawing is realized.

[0025] In the process of processing the cobalt-based high-temperature alloy wire, atmospheric annealing at 1150-1200℃ is carried out, and water quenching is carried out, so that the gamma phase (such as Figure 1 ) is formed. The gamma phase is a soft phase and is easy to draw. During cold drawing, the gamma phase is converted into the epsilon phase, the epsilon phase is a hard phase, and the obtained wire has high tensile strength.

[0026] Example 1

[0027] (1) Wire preparation: The cobalt-based high-temperature alloy ingot is prepared by a two-link process of vacuum induction melting + gas shielded electroslag remelting. The melted ingot is subjected to forging-rolling-scaling-hot drawing to obtain cobalt-based high-temperature alloy disc material. The disc material is subjected to sizing and scaling to obtain φ2.75mm cobalt-based high-temperature alloy wire raw material.

[0028] (2) Heat treatment: The above-mentioned cobalt-based high-temperature alloy wire raw material is loaded into an annealing furnace, atmospheric annealing is carried out, the temperature is raised to 1200℃, and the temperature is kept for 60min, and then water quenching is carried out to room temperature.

[0029] (3) Cold drawing: the cobalt-based superalloy wire after heat treatment is drawn for 4 batches, each batch is drawn for 4 passes, the deformation of each pass is 14-15%, the total deformation of each batch (i.e. the deformation of each pass) is 35%-60%, here it is 46%, the drawing speed is 10 m / min, and heat treatment is needed before each batch of cold drawing process.

[0030] The heat treatment process is as follows: the cobalt-based superalloy wire obtained after the last batch of cold drawing process is put into an annealing furnace, heated to 1200°C, air annealed, held for 60 min, and water quenched to room temperature.

[0031] The φ2.75 mm wire material is drawn for 4 batches to obtain a φ0.8 mm wire. The specific process is shown in Tables 1-4. In the table, the front number of each row of data in the drawing size column represents the diameter of the wire before this pass, and the rear number represents the diameter after this pass.

[0032] Table 1 First batch of drawing

[0033]

[0034] Table 2 Second batch of drawing

[0035]

[0036] Table 3 Third batch of drawing

[0037]

[0038] Table 4 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 is subjected to current online annealing pre-oxidation, i.e. the wire passes through two charged conductive wheels with a distance of 1.5 m, the time from entering the first conductive wheel to leaving the second conductive wheel at any point on the wire 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, here it is 30 A, the wire after current annealing is bright red, and the wire coming out of the second conductive wheel is immediately water sprayed and water quenched to room temperature.

[0041] (5) cold drawing: the wire with φ0.753 mm after heat treatment is drawn for 4 batches, the pass of each batch is 5, the deformation of each pass is 12-13%, the total deformation of each batch (i.e. the deformation of each pass) is 40%-60%, here 45-50%, the drawing speed is 15 m / min, after 5-7 batches of cold drawing process, the wire is heat treated, and then the next batch of cold drawing is carried out;

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

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

[0044] Table 5 fifth batch drawing

[0045]

[0046]

[0047] Table 6 sixth batch drawing

[0048]

[0049] Table 7 seventh batch drawing

[0050]

[0051] Table 8 eighth batch drawing

[0052]

[0053] The cobalt-based alloy wire with a diameter of 0.2 mm prepared in the embodiment and the imported cobalt-based alloy wire with a diameter of 0.2 mm purchased on the market were subjected to mechanical property tests according to the standard GB / T 228.1-2021, and the comparison results of tensile strength, yield strength, elongation and reduction of area are shown in Table 9. The cobalt-based alloy wire prepared in the embodiment has higher tensile strength and yield strength under the condition that the elongation and reduction of area are equivalent to those of the imported wire. Figure 2 The grain size in the formula is 10.5, and the more the number of grains in a unit volume, the more the number of grain boundaries. The grain boundary is a zone where various distortions, defects and impurities in the metal are aggregated, which hinders the movement of dislocations, thereby increasing the deformation resistance and improving the strength of the material. Figure 3 The cobalt-based high-temperature alloy wire product has a bright surface.

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

[0055]

[0056] The embodiment is only for illustrating the technical concept and characteristics of the present application, and its purpose is to enable those skilled in the art to understand the content of the present application and to implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made in accordance with the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A method of producing a high-strength cobalt-based alloy wire, characterized by: The cobalt-based alloy wire material is taken as raw material, and is cold-drawn for 4-10 batches, and is heat-treated before each batch of cold-drawing, and is surface-treated after the last batch of cold-drawing to obtain the finished wire; the cold-drawing is performed for 4-10 batches, each batch is performed for 2-6 passes, the pass deformation is 8-16%, and the fire deformation of each batch is 35-60%; The cobalt-based alloy wire material raw material has the following components by mass percentage: 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 of Co, and the wire material raw material has a diameter of 2.5-3 mm; The heat treatment process is one of the following two cases: A: air annealing, the annealing temperature is 1150-1250℃, the holding time is 30-90 min, and then water quenching to room temperature; B: current online annealing, the current is set to 25-50 A, the annealing time is 5-20 s, and then water quenching to room temperature; The cold-drawing speed is 10-35 m / min, and the pass deformation of each batch is the same or similar; the similar means that the difference between the maximum and minimum values of the pass deformation is ≤1%.

2. The method of claim 1, wherein: The target diameter of the wire is greater than 0.8 mm, and the heat treatment is performed in the A mode; the target diameter of the wire is less than 0.8 mm, and the heat treatment is performed in the B mode; the target diameter of the wire is 0.8 mm, and either the A or B heat treatment mode can be used.

3. The method of claim 1, wherein: The surface treatment process is that the drawn wire is subjected to electrolytic polishing.

4. The method of claim 3, wherein: The electrolytic polishing is performed in a 9-12% mass fraction chromium trioxide aqueous solution, the current density is 0.2-1.5 A / cm², the voltage is set to 40-60 V, and the polishing time is 10-50 s.

5. A cobalt-based alloy wire produced according to the production method of any one of claims 1 to 4, characterized by: The wire diameter is 0.2-0.8 mm, and the grain size is 9-12 levels.

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