Small-diameter cobalt-based alloy continuous casting rod and production process thereof

Abstract

The invention discloses a small-diameter cobalt-based alloy continuous casting rod and a production process thereof, and relates to the technical field of metal processing. The method specifically comprises the following steps that S1, alloy raw materials, tantalum and niobium are added into a smelting furnace, under the vacuum condition, after heating and melting are conducted, stirring is conducted, an alterant is added, stirring and pouring are conducted continuously, and an alloy ingot is obtained; s2, the alloy ingot is transferred into a vacuum continuous casting furnace, a crystallizer and a cooling water system are connected with a separation ring, vacuumizing is conducted, the alloy ingot is heated to be molten, argon is introduced, blank drawing and rod manufacturing are conducted through a wire drawing die, cutting is conducted, and a cast rod is obtained; the process provided by the invention can be used for preparing casting rods with the diameters of 2.3 mm, 2.4 mm and 2.5 mm, and the casting rods have higher hardness and corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of metal processing, and particularly to a continuous casting rod of small-diameter cobalt-based alloy and its production process. Background Art

[0002] Cobalt-based alloys take cobalt as the main component, contain relatively large amounts of nickel, chromium, tungsten and a small amount of other elements, and have excellent wear resistance and high-temperature resistance. They can maintain stable mechanical properties at temperatures up to 1000°C, and are ideal materials for preparing high-temperature equipment and parts. At the same time, they have good biocompatibility and can also be used to manufacture human joints, surgical tools, etc.

[0003] However, due to its high melting point, large hardness and brittleness, and poor hot plasticity even at high temperatures, this characteristic makes it difficult to use the rolling process, especially in the production process of small-diameter cobalt-based alloy casting rods, and the production difficulty is high. In traditional technologies, when preparing small-diameter cobalt-based alloy casting rods, a master alloy ingot is often prepared first, and then a cylindrical casting rod is directly cut by wire cutting. However, due to stress concentration and temperature changes during the cutting process, cracks may appear on its surface and inside, resulting in reduced performance. In addition, small-diameter cobalt-based alloy casting rods also have the problem of poor corrosion resistance.

[0004] In summary, to solve the above problems, it is of great significance to provide a continuous casting rod of small-diameter cobalt-based alloy with high hardness and good corrosion resistance and its production process. Summary of the Invention

[0005] The purpose of the present invention is to provide a continuous casting rod of small-diameter cobalt-based alloy and its production process to solve the problems raised in the prior art.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] A production process of a continuous casting rod of small-diameter cobalt-based alloy includes the following steps:

[0008] S1: Add alloy raw materials, tantalum, and niobium into a melting furnace, heat and melt them under vacuum conditions, stir for 15 - 20 min, add a modifier, continue to stir for 5 - 10 min, and then pour to obtain an alloy ingot;

[0009] S2: Transfer the alloy ingot to a vacuum continuous casting furnace, connect the mold and the cooling water system to the separation ring, evacuate to 2 - 5 Pa, heat the alloy ingot to melting, introduce argon until the furnace pressure is 0.07 - 0.09 MPa, draw and form a rod with a wire drawing die, and then cut to obtain a casting rod.

[0010] Preferably, in step S2, the diameter of the mold is 2.5 - 3.0 mm; the separation ring includes one of a boron nitride separation ring and a zirconia separation ring;

[0011] More preferably, the inlet cone angle of the wire drawing die is 65-75°, and the outlet cone angle is 30-35°.

[0012] More preferably, in step S2, during the process of drawing the blank into a rod, the speed is 10-20 mm / min.

[0013] More preferably, the mass ratio of the alloy raw material, tantalum, and niobium is 100:0.4-0.7:0.6-0.8; the alloy raw material includes the following elements, by mass fraction: cobalt: 40-45%, chromium: 20-24%, nickel: 21-23%, tungsten: 13-15%, manganese: 1-1.5%, silicon: 0.01-0.02%, and the balance is iron.

[0014] More preferably, the modifier includes silicon, cerium, and lanthanum with a mass ratio of 10:1-2:1-1.5.

[0015] More preferably, the addition amount of the modifier accounts for 1-3 wt% of the total raw materials.

[0016] More preferably, the production process of the small-diameter cobalt-based alloy continuous casting ingot provided by the present invention can produce ingots with diameters of 2.3 mm, 2.4 mm, and 2.5 mm.

[0017] Compared with the prior art, the beneficial effects of the present application are as follows:

[0018] (1) The continuous casting process casts the molten metal into a continuous casting billet of a predetermined shape through continuous casting, and then through processing such as cooling and cutting, finally obtains the required ingot or plate rod and other products. The process flow is simple and the energy consumption is small; due to its continuous casting and forming characteristics, it has great advantages for metals such as cobalt-based alloys that have high hardness, poor plasticity at room temperature and high temperature, are difficult to deform, and are difficult to use rolling and wire drawing processes but require the preparation of small-diameter ingots. The present invention uses boron nitride and zirconia materials with high-temperature resistance characteristics as the separating ring, and at the same time it has low wettability to the molten metal, which can reduce the adhesion and accumulation of the molten metal on the separating ring; using a special-shaped wire drawing die helps to reduce the resistance during the wire drawing process, dissipate the deformation heat, and improve the performance of the ingot; and the specific inlet cone angle and outlet cone angle of the wire drawing die help to reduce the cracks generated by stress concentration in the ingot during the production process, and improve the hardness and corrosion resistance of the ingot

[0019] (2) The cobalt-based alloy prepared by the present invention contains tantalum, which is beneficial to improving the toughness of the alloy and reducing the possibility of fracture of small-diameter casting rods; adding niobium can increase the hardness and strength of the alloy; silicon contained in the added modifier helps to reduce the melting point of the alloy liquid, and has the effects of deoxidation and slag formation, improving the purity of the alloy; adding lanthanum and cerium can improve the oxidation resistance of the alloy, enhance the strength and hardness, and improve the corrosion resistance; and the later addition of the modifier also helps to reduce the burning of low-melting metals, thereby improving the performance of the cobalt-based alloy prepared into small-diameter cobalt-based alloy casting rods. Specific embodiments

[0020] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0021] In the following embodiments, "parts" are by mass, and the raw materials are all commercially available.

[0022] Among them, in the following embodiments, the alloy raw materials include the following elements, by mass fraction: cobalt: 40-45%, chromium: 20-24%, nickel: 21-23%, tungsten: 13-15%, manganese: 1-1.5%, silicon: 0.01-0.02%, and the balance is iron; the modifier includes silicon, cerium, and lanthanum with a mass ratio of 10:1.5:1.

[0023] Example 1: A production process for a small-diameter cobalt-based alloy continuous casting rod, comprising the following steps:

[0024] S1: Add the alloy raw materials, tantalum, and niobium to a melting furnace at a mass ratio of 100:0.5:0.5, heat and melt under vacuum conditions, stir for 15 min, add 2 wt% of the total raw materials of the modifier, continue to stir for 5 min, and pour to obtain an alloy ingot;

[0025] S2: Transfer the alloy ingot to a vacuum continuous casting furnace, connect the mold and the cooling water system to the separation ring, evacuate to 5 Pa, heat the alloy ingot to melting, introduce argon until the furnace pressure is 0.08 MPa, draw the billet at a speed of 15 mm / min with a wire drawing die, and cut to obtain the casting rod.

[0026] Example 2: A production process for a small-diameter cobalt-based alloy continuous casting rod, comprising the following steps:

[0027] S1: Add the alloy raw materials, tantalum, and niobium to a melting furnace at a mass ratio of 100:0.4:0.6, heat and melt under vacuum conditions, stir for 15 min, add 1 wt% of the total raw materials of the modifier, continue to stir for 5 min, and pour to obtain an alloy ingot;

[0028] S2: Transfer the alloy ingot to a vacuum continuous casting furnace, connect the crystallizer and the cooling water system to the separation ring. When the vacuum reaches 5 Pa, heat the alloy ingot to melting, introduce argon until the furnace pressure is 0.08 MPa, draw and form a rod at a speed of 15 mm / min with a wire drawing die, and cut to obtain a cast rod.

[0029] Example 3: A production process for a small-diameter cobalt-based alloy continuous casting rod, comprising the following steps:

[0030] S1: Add alloy raw materials, tantalum, and niobium to a melting furnace at a mass ratio of 100:0.7:0.8. After heating and melting under vacuum conditions, stir for 15 min, add a modifier accounting for 3 wt% of the total raw materials, continue stirring for 10 min, and pour to obtain an alloy ingot;

[0031] S2: Transfer the alloy ingot to a vacuum continuous casting furnace, connect the crystallizer and the cooling water system to the separation ring. When the vacuum reaches 5 Pa, heat the alloy ingot to melting, introduce argon until the furnace pressure is 0.08 MPa, draw and form a rod at a speed of 15 mm / min with a wire drawing die, and cut to obtain a cast rod.

[0032] Comparative Example 1: Based on Example 1, without adding tantalum and niobium, and keeping the rest of the process unchanged, specifically as follows:

[0033] S1: Add alloy raw materials to a melting furnace. After heating and melting under vacuum conditions, stir for 15 min, add a modifier accounting for 2 wt% of the total raw materials, continue stirring for 5 min, and pour to obtain an alloy ingot;

[0034] S2: Transfer the alloy ingot to a vacuum continuous casting furnace, connect the crystallizer and the cooling water system to the separation ring. When the vacuum reaches 5 Pa, heat the alloy ingot to melting, introduce argon until the furnace pressure is 0.08 MPa, draw and form a rod at a speed of 15 mm / min with a wire drawing die, and cut to obtain a cast rod.

[0035] Comparative Example 2: Based on Example 1, increase the amount of the modifier, and keep the rest of the process unchanged, specifically as follows:

[0036] S1: Add alloy raw materials, tantalum, and niobium to a melting furnace at a mass ratio of 100:0.5:0.5. After heating and melting under vacuum conditions, stir for 15 min, add a modifier accounting for 6 wt% of the total raw materials, continue stirring for 5 min, and pour to obtain an alloy ingot;

[0037] S2: Transfer the alloy ingot to a vacuum continuous casting furnace, connect the crystallizer and the cooling water system to the separation ring. When the vacuum reaches 5 Pa, heat the alloy ingot to melting, introduce argon until the furnace pressure is 0.08 MPa, draw and form a rod at a speed of 15 mm / min with a wire drawing die, and cut to obtain a cast rod.

[0038] Performance Test: (1) Referring to the reference document GB / T4340.1-2024, the microhardness tester MC010 was used to test the hardness of the samples in each example, and the Vickers hardness value was calculated. The experimental data are shown in Table 1; (2) Referring to the document GB / T5776-2023, the corrosion resistance experiment was carried out on the samples in each example. The test solution includes the following substances: 10wt% FeCl·6H2O, 0.05mol / L HCl; the experimental data are shown in Table 1.

[0039] Table 1

[0040]

[0041] Conclusion: As can be seen from Table 1, in Comparative Example 1, tantalum and niobium were not added, and both the hardness and corrosion resistance decreased; in Comparative Example 2, the addition amount of the modifier was increased, resulting in the formation of an uneven inclusion region, which damaged the integrity of the grain boundary, and the hardness and corrosion resistance decreased.

[0042] In summary, the present invention successfully provides a production process for continuously casting small-diameter cobalt-based alloy ingots by setting a separation ring with high-temperature resistance characteristics and a wire drawing die with a special shape, and introducing tantalum and niobium. The prepared ingots have a small diameter and high hardness and corrosion resistance.

[0043] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A production process for small-diameter cobalt-based alloy continuous casting rods, characterized in that: The following steps are involved: S1: Add alloy raw materials, tantalum and niobium into a smelting furnace, heat and melt them under vacuum conditions, stir for 15 to 20 minutes, add a modifier, continue stirring for 5 to 10 minutes, and cast to obtain an alloy ingot; S2: Transfer the alloy ingot to a vacuum continuous casting furnace, connect the crystallizer and cooling water system to the separation ring, evacuate to 2-5 Pa, heat the alloy ingot until it is molten, introduce argon gas to a furnace pressure of 0.07-0.09 MPa, draw the blank into a rod with a drawing die, cut it, and obtain a cast rod.

2. The production process of a small-diameter cobalt-based alloy continuous casting rod according to claim 1, characterized in that: In step S2, the diameter of the crystallizer is 2.5-3.0 mm; the separation ring includes a boron nitride separation ring and a zirconium oxide separation ring.

3. The production process of a small-diameter cobalt-based alloy continuous casting rod according to claim 1, characterized in that: The inlet cone angle of the wire drawing die is 65-75°, and the outlet cone angle is 30-35°.

4. The production process of a small-diameter cobalt-based alloy continuous casting rod according to claim 1 is characterized in that: In step S2, during the process of drawing the embryo and making the rod, the speed is 10-20 mm / min.

5. The production process of a small diameter cobalt-based alloy continuous casting rod according to claim 1, characterized in that: The mass ratio of the alloy raw material, tantalum and niobium is 100:0.4-0.7:0.6-0.8; the alloy raw material includes the following elements, calculated by mass fraction: cobalt: 40-45%, chromium: 20-24%, nickel: 21-23%, tungsten: 13-15%, manganese: 1-1.5%, silicon: 0.01-0.02%, and the balance is iron.

6. The production process of a small diameter cobalt-based alloy continuous casting rod according to claim 1, characterized in that: The modifier includes silicon, cerium and lanthanum in a mass ratio of 10:1 to 2:1 to 1.

5.

7. The production process of a small diameter cobalt-based alloy continuous casting rod according to claim 1, characterized in that: The amount of the modifier added is 1-3 wt % of the total raw materials.

8. A small diameter cobalt-based alloy continuous casting rod, characterized in that: The invention is prepared by the production process of a small-diameter cobalt-based alloy continuous casting rod as described in any one of claims 1 to 7.

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