A preparation method for a medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire

Abstract

The present invention discloses a method for preparing a medical titanium-zirconium alloy bar and wire, including ingot casting, forging, quenching, hot rolling, quenching, cold rolling, recrystallization annealing, severe plastic deformation, drawing, straightening, annealing and surface treatment processes. By introducing high-density defects into the material through severe plastic deformation and combining with quenching heat treatment to regulate the microstructure of the alloy, the preparation of a titanium-zirconium alloy with high strength and plasticity and good fracture toughness can be achieved. It is possible to mass-produce equiaxed ultrafine-grained titanium-zirconium alloy bars and wires with a diameter between 1 mm and 8 mm and a length greater than 600 mm, and high strength and high fatigue strength can be obtained, meeting the requirements of dental medical devices for raw materials.

Description

Technical Field

[0001] The present invention relates to the technical field of biomaterial preparation, and more specifically, to a method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy bars and wires. Background Art

[0002] In dental medical devices, the widely used metallic materials are pure titanium and Ti-6Al-4V. However, the strength of pure titanium is insufficient, and the elastic modulus of Ti-6Al-4V is relatively high and the V element is toxic. Titanium-zirconium alloy has a low elastic modulus, excellent mechanical properties, good corrosion resistance and biocompatibility, and thus becomes a new type of raw material for dental devices.

[0003] Currently in the industry, by using traditional thermo-mechanical processing methods, cylindrical Ti-15Zr titanium alloy bars and wires with a diameter of Φ1mm - 8mm can be prepared. However, the raw materials of such Ti-15Zr bars and wires are not ultrafine-grained materials. Therefore, there are key problems such as low strength and poor wear resistance, which do not meet the requirements of medical devices.

[0004] Continuous equal-channel angular extrusion technology, which combines equal-channel angular extrusion and continuous extrusion processes to achieve the preparation of large-size ultrafine-grained materials. Although it can produce large-size ultrafine-grained Ti-15Zr alloy bars and wires, the accumulated strain is small during a single processing, and multiple processing times are often required to generate large deformation, with repeated extrusion, resulting in low processing efficiency. Moreover, the ultrafine grains are not equiaxed crystals, and there are problems such as uneven deformation of the formed material and poor uniformity of the tissue properties of the obtained material products.

[0005] Therefore, there is an urgent need to provide a method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy bars and wires that can prepare large-size equiaxed ultrafine-grained titanium-zirconium alloy bars and wires. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects existing in the prior art and provide a method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy bars and wires.

[0007] To achieve the above purpose, the technical solution of the present invention is as follows:

[0008] A method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy bars and wires, characterized by comprising:

[0009] S1. Mixing sponge titanium, sponge zirconium, and zirconium dioxide in a preset ratio and melting them into an ingot;

[0010] S2. After heat-preserving the ingot at 850°C - 1000°C, performing forging to obtain a forging blank;

[0011] S3. Performing a first quenching treatment on the forging blank;

[0012] S4. After holding the forged blank at 770°C - 840°C, perform rolling to obtain a rolled bar.

[0013] S5. Perform a second quenching treatment on the rolled bar.

[0014] S6. At room temperature, perform rolling on the rolled bar to obtain an ultrafine-grained bar blank.

[0015] S7. Perform recrystallization annealing on the ultrafine-grained bar blank.

[0016] S8. Subject the ultrafine-grained bar blank to severe plastic deformation processing to obtain an equiaxed ultrafine-grained bar blank.

[0017] S9. At room temperature, perform drawing and diameter reduction on the equiaxed ultrafine-grained bar blank to obtain bar wire.

[0018] S10. Straighten the bar wire.

[0019] S11. Perform annealing on the bar wire.

[0020] S12. Perform surface treatment on the bar wire to obtain qualified bar wire.

[0021] Implementing the embodiments of the present invention will have the following beneficial effects:

[0022] The embodiments of the present invention disclose a method for preparing an equiaxed ultrafine-grained medical titanium-zirconium alloy bar wire, including ingot casting, forging, quenching, hot rolling, quenching, cold rolling, recrystallization annealing, severe plastic deformation, drawing, straightening, annealing, and surface treatment processes. By introducing high-density defects inside the material through severe plastic deformation and combining quenching heat treatment to regulate the microstructure of the alloy, the preparation of a titanium-zirconium alloy with high strength, high plasticity, and good fracture toughness can be achieved. It is possible to mass-produce equiaxed ultrafine-grained titanium-zirconium alloy bar wires with a diameter between 1 mm and 8 mm and a length greater than 600 mm, and high strength and high fatigue strength can be obtained, meeting the requirements of dental medical devices for raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0024] Among them:

[0025] Figure 1 is a flowchart of a method for preparing a medical equiaxed ultrafine-grained titanium-zirconium alloy bar wire provided by the present invention.

[0026] Figure 2 It is a schematic diagram of the severe plastic deformation die provided by the present invention. Specific implementation mode

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0028] Refer to Figure 1 , the present invention discloses a preparation method of a medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire, including:

[0029] S1. Mix sponge titanium, sponge zirconium, and zirconium dioxide in a preset ratio, and melt them into an ingot through a vacuum consumable arc furnace;

[0030] S2. After the ingot is kept warm at 850°C - 1000°C, perform forging to obtain a forging blank;

[0031] S3. Perform the first quenching treatment on the forging blank;

[0032] S4. After the forging blank is kept warm at 770°C - 840°C, perform rolling to obtain a rolled bar;

[0033] S5. Perform the second quenching treatment on the rolled bar;

[0034] S6. Perform rolling on the rolled bar at room temperature to obtain an ultrafine-grained bar blank;

[0035] S7. Perform recrystallization annealing treatment on the ultrafine-grained bar blank;

[0036] S8. The ultrafine-grained bar blank is processed by severe plastic deformation to obtain an equiaxed ultrafine-grained bar blank;

[0037] S9. Perform drawing and diameter reduction on the equiaxed ultrafine-grained bar blank at room temperature to obtain a bar and wire;

[0038] S10. Use a straightening device to straighten the bar and wire;

[0039] S11. Perform annealing treatment on the bar and wire;

[0040] S12. Perform surface treatment on the bar and wire to obtain qualified bar and wire.

[0041] It should be noted that the titanium-zirconium alloy bar and wire prepared in this embodiment include the following components by mass percentage: Zr: 14-16.5%, and the balance is Ti and inevitable impurities. The inevitable impurities are the impurities in the added sponge zirconium and sponge titanium, where: 0 < C ≤ 0.10%, 0 < O ≤ 0.20%, 0 < N ≤ 0.05%, 0 < H ≤ 0.08%, 0 < Fe ≤ 0.25%.

[0042] Specifically, in step S1, sponge titanium, sponge zirconium, and ZrO2 powder are proportioned according to a preset ratio; melted 3-4 times in a vacuum consumable arc furnace, with a vacuum degree of 10 -1 Pa - 10 -3 Pa, a working current of 1 kA - 10 kA, and a working voltage of 10 V - 50 V to obtain a titanium-zirconium alloy ingot.

[0043] In step S2, after the ingot is held at the β-phase temperature range (850°C - 1000°C) of the titanium-zirconium alloy for 1 h - 5 h, it is air-cooled and free-forged using a quick forging machine, with a deformation amount per heat not less than 50% to obtain a forged blank.

[0044] In step S3, the first quenching treatment is performed on the forged blank, specifically including: quickly water-cooling or liquid nitrogen-cooling the forged blank obtained by forging after being held at the β-phase temperature range of the titanium-zirconium alloy for 1 h - 3 h.

[0045] After the ingot is quickly cooled after being held in the β-phase region, the structure forms dispersed α' acicular martensite.

[0046] In step S4, after the forged blank is held at the α + β-phase temperature range (770°C - 840°C) of the titanium-zirconium alloy for 1 - 3 h, it is rolled using a tandem mill, with a single-pass deformation rate less than 15% to obtain a rolled bar.

[0047] After the forged blank is held at the α + β-phase temperature range and then hot-rolled, the martensite structure inside the material deforms, and the dislocations are rearranged to form a new fine sub-micron grain structure, which can effectively improve the strength of the material.

[0048] In step S5, the second quenching treatment is performed on the rolled bar, specifically including: quickly water-cooling or liquid nitrogen-cooling the rolled bar obtained by rolling after being held at the α + β-phase temperature range of the titanium-zirconium alloy for 1 h - 3 h.

[0049] After the rolled bar is quickly cooled after being held in the α + β-phase region, an α + α' organizational structure is formed. The soft and ductile α-phase provides excellent elongation, so that subsequent cold rolling at room temperature does not crack.

[0050] In step S6, the rolled bar is rolled using a cold rolling mill at room temperature, with a single-pass deformation amount less than 15% and a total deformation amount greater than 50%.

[0051] Room temperature cold rolling can further fully crush the grains inside the rolled bar to obtain an ultrafine-grained bar blank, and at this time, the ultrafine-grained bar blank is a non-equiaxed ultrafine-grained bar blank.

[0052] The recrystallization annealing in step S7 includes air-cooling the ultrafine-grained bar blank after holding it at 600°C - 700°C for 0.5 h - 3 h. The work hardening phenomenon in the material after cold deformation processing is eliminated through recrystallization annealing, and the plasticity and toughness of the material are restored and improved.

[0053] In step S8, an equiaxed ultrafine-grained alloy bar blank is prepared by severe plastic deformation methods, and the severe plastic deformation methods include techniques such as high-pressure torsion, equal-channel angular pressing, multi-directional forging, etc.

[0054] Optionally, in step S8, the bar blank is cut to a fixed length and then equal-channel angular pressing is carried out. The die drawing is Figure 2 , and the corner angle α is 120°. Among them, molybdenum disulfide is used as a lubricant, and the equal-channel angular pressing processing speed is between 1 mm / s - 10 mm / s. Each time the bar blank passes through the die is one pass, and the specimen rotates 90° clockwise between each pass. The processing temperature is between 400°C - 500°C, and the number of processing passes is between 4 - 8 passes.

[0055] Optionally, the die diameter for equal-channel angular pressing of the original bar includes but is not limited to 8 mm - 20 mm, and the die can process bars between 2 mm - 20 mm. The turning radius of the die includes but is not limited to 120°, and the turning radius can be between 90° - 160°.

[0056] In step S9, multi-pass room temperature drawing is carried out using a roller grinding and drawing device, and the single-pass deformation amount is between 10% - 15%. Subsequently, stress relief annealing is carried out, and bar wires are obtained after multi-pass drawing.

[0057] Through the cycle of room temperature drawing and stress relief annealing, further diameter reduction processing of the equiaxed ultrafine-grained alloy bar blank can obtain bar wires with a length greater than 1 m and specifications close to the finished product requirements.

[0058] In step S10, the bar wires are first cut into the required length and then straightened using a straightening device, and the straightness is controlled to be ≤ 1 mm / m.

[0059] In step S11, the bar wires are annealed using an annealing furnace at a temperature of 450°C - 650°C for a time of 20 min - 90 min.

[0060] In step S12, a centerless grinder, pickling and polishing or plasma polishing surface treatment equipment is used to perform surface treatment on the bar wires to remove the oxide scale on the surface of the bar wires. The surface roughness of the qualified bar wires is less than or equal to 0.8 μm. An ultrafine-grained titanium-zirconium alloy bar wire with a bright surface, in an annealed state, and excellent straightness is obtained.

[0061] It is understandable that, on the one hand, the preparation method of the medical equiaxed ultrafine-grained titanium-zirconium alloy bar and wire provided by the present invention can produce medical ultrafine-grained titanium-zirconium alloy bars and wires of various specifications, providing qualified raw materials for dental medical devices. On the other hand, the present invention improves the strength of titanium by adding titanium and zirconium elements harmless to the human body to meet the strength and wear resistance required for implants. At the same time, the risk of human injury caused by the precipitation of harmful elements is eliminated, and the requirements for the performance of raw materials for medical devices are also met. On the other hand, the present invention adopts a special processing technology, that is, a method combining severe plastic deformation and heat treatment. That is, high-density defects (such as dislocations) are introduced into the material through severe plastic deformation, and the microstructure of the alloy is regulated by quenching heat treatment to realize the preparation of a titanium-zirconium alloy with high strength and plasticity and good fracture toughness. It is possible to mass-produce equiaxed ultrafine-grained titanium-zirconium alloy bars and wires with a diameter between 1 mm and 8 mm and a length greater than 600 mm, and high strength and high fatigue strength can be obtained to meet the requirements of dental medical devices for raw materials.

[0062] Example 1

[0063] For the titanium-zirconium alloy bar and wire in this example, its mass percentage includes: Zr: 15.15%, C: 0.004%, O: 0.193%, N: 0.018%, H: 0.008%, Fe: 0.028%, and the balance is Ti.

[0064] The preparation method of the titanium-zirconium alloy bar and wire in this example includes:

[0065] Step 1: Charge sponge titanium, sponge zirconium, and ZrO2 powder according to the composition of the titanium-zirconium alloy, and carry out vacuum consumable melting four times. The vacuum degree of the first melting is 5×10 -3 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree of the second melting is 10 -2 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree of the third melting is 10 -1 Pa, the working current is 8.0 kA, and the working voltage is 30 V; the vacuum degree of the fourth melting is 10 -1 Pa, the working current is 7.5 kA, and the working voltage is 30 V; obtain a Φ260 mm Ti-Zr alloy ingot.

[0066] Step 2: At 900 °C, keep the ingot warm for 2 h, and then carry out free forging with a quick forging machine. The deformation amount per heating is controlled at 60% to obtain a Φ120 mm forging blank.

[0067] Step 3: Keep the forging blank warm at 900 °C for 1.5 h and then quickly water-cool it for quenching.

[0068] Step 4: At 800 °C, keep the forging blank warm for 1.5 h, then roll it using a Y-type three-high continuous rolling mill, with the deformation per pass controlled at 13% to obtain a rolled bar with a diameter of Φ12 mm.

[0069] Step 5: Keep the rolled bar warm at 780 °C for 1 h and then rapidly water-cool it for quenching.

[0070] Step 6: Continuously cold-roll the rolled bar using a cold-rolling device, with the deformation per single pass being 10%. After the total deformation reaches 40% - 45%, conduct intermediate annealing with an annealing regime of 650 °C for 1 h. After repeating this process multiple times, obtain a Φ6 mm ultrafine-grained bar blank.

[0071] Step 7: Keep the bar blank warm at 700 °C for 0.5 h and then air-cool it for recrystallization annealing heat treatment.

[0072] Step 8: Cut the bar blank to a fixed length of 500 mm, then perform equal-channel angular pressing to obtain an equiaxed ultrafine-grained alloy bar blank. The processing temperature is 400 °C, the rotation angle is 120°, use molybdenum disulfide as a lubricant, the processing speed is between 5 mm / s, the bar blank rotates 90° clockwise after each pass through the die, and the number of processing passes is 6.

[0073] Step 9: Cold-draw the equiaxed ultrafine-grained alloy bar blank at room temperature using a drawing device, with the deformation per single pass being 11 - 13%. Use a lubricating fluid for lubrication, conduct intermediate annealing at 650 °C for 1 h, and then perform cold drawing again. After repeating this process multiple times, obtain a Φ4 mm bar wire.

[0074] Step 10: Cut the bar wire to a fixed length of 1000 mm per piece, then straighten the bar wire using a slider straightening machine. After straightening, the straightness is within 0.3 mm / m.

[0075] Step 11: Keep the bar wire warm at 600 °C for 40 min for annealing.

[0076] Step 12: Remove the surface oxide layer of the annealed bar wire using a centerless grinder and polish it using a wet polishing method. The surface roughness of the bar wire is 0.4 μm.

[0077] Table 1 shows the mechanical property test results of the Φ4.0 mm titanium-zirconium alloy bar wire obtained in Example 1

[0078]

[0079] Example 2

[0080] In the titanium-zirconium alloy bar wire of this example, its mass percentage includes: Zr: 15.60%, C: 0.008%, O: 0.189%, N: 0.009%, H: 0.005%, Fe: 0.022%, and the balance is Ti.

[0081] The preparation method of the titanium-zirconium alloy bar and wire in this embodiment includes:

[0082] Step 1: Charge sponge titanium, sponge zirconium, and ZrO2 powder according to the composition of the titanium-zirconium alloy, and perform vacuum consumable melting three times. The vacuum degree for the first melting is 4×10 -3 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree for the second melting is 10 -2 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree for the third melting is 10 -1 Pa, the working current is 8.0 kA, and the working voltage is 30 V; obtain a Φ280 mm Ti-Zr alloy ingot.

[0083] Step 2: At 900 °C, after holding the ingot for 2 h, perform free forging with a quick forging machine, and control the deformation amount per heat to 65% to obtain a Φ140 mm forging blank.

[0084] Step 3: After holding the forging blank at 900 °C for 1.5 h, quickly cool it with water for quenching.

[0085] Step 4: At 780 °C, after holding the forging blank for 1.5 h, perform rolling with a Y-type three-roll continuous rolling mill, and control the deformation amount per pass to 12% to obtain a Φ10 mm rolled bar.

[0086] Step 5: After holding the rolled bar at 780 °C for 1 h, quickly cool it with water for quenching.

[0087] Step 6: Use a cold rolling device to continuously cold roll the rolled bar, with a single-pass deformation amount of 12%. After the deformation amount reaches 40%-45%, perform intermediate annealing, and the annealing system is 650 °C, 1 h. After repeating this process many times, obtain a Φ6 mm ultrafine-grained bar blank.

[0088] Step 7: After holding the bar blank at 680 °C for 0.5 h, air-cool it for recrystallization annealing heat treatment.

[0089] Step 8: Cut the bar blank to a fixed length of 500 mm, cut it into blanks, and perform equal-channel angular pressing to obtain an equiaxed ultrafine-grained bar blank. The processing temperature is 450 °C, the corner angle is 120°, use molybdenum disulfide as a lubricant, the processing speed is between 5 mm / s, the bar blank rotates 90° clockwise after each pass through the die, and the number of processing passes is 6.

[0090] Step 9: Use a drawing device to perform cold drawing on the equiaxed ultrafine-grained bar blank, with a single-pass deformation amount of 10-12%. Use a lubricating fluid for lubrication, perform intermediate annealing at 600 °C for 1 h, and then perform cold drawing. After repeating this process many times, obtain a Φ5 mm bar and wire.

[0091] Step Ten: Cut the rod wire into fixed lengths of 1000 mm each, and straighten the rod wire using a slider straightening machine. After straightening, the straightness is 0.2 mm / m.

[0092] Step Eleven: Anneal the rod wire by holding it at 600 °C for 60 min.

[0093] Step Twelve: Remove the surface oxide layer of the annealed rod wire using a centerless grinder, and polish it using a plasma polishing machine. The surface roughness of the wire is 0.18 μm.

[0094] Table 2 shows the mechanical property test results of the Φ5.0 mm titanium-zirconium alloy rod wire obtained in Example 2.

[0095]

[0096] Example 3

[0097] In this example, the titanium-zirconium alloy rod wire has the following mass percentages: Zr: 16.20%, C: 0.005%, O: 0.191%, N: 0.005%, H: 0.002%, Fe: 0.019%, and the balance is Ti.

[0098] The preparation method of the titanium-zirconium alloy rod wire in this example includes:

[0099] Step One: Charge sponge titanium, sponge zirconium, and ZrO2 powder according to the composition of the titanium-zirconium alloy, and carry out vacuum consumable melting three times. The vacuum degree for the first melting is 5×10 -3 Pa, the working current is 7.0 kA, and the working voltage is 30 V; the vacuum degree for the second melting is 10 -1 Pa, the working current is 6.0 kA, and the working voltage is 30 V; the vacuum degree for the third melting is 10 -1 Pa, the working current is 7.5 kA, and the working voltage is 30 V; obtain a Φ460 mm Ti-Zr alloy ingot.

[0100] Step Two: At 950 °C, hold the ingot for 2 h, and then carry out free forging using a quick forging machine. The deformation per heat is controlled at 70% to obtain a Φ160 mm rod blank.

[0101] Step Three: Hold the forged blank at 950 °C for 1.5 h and then quickly water-cool it for quenching.

[0102] Step Four: At 820 °C, hold the forged blank for 1.5 h, and then roll it using a Y-type three-high continuous rolling mill. The deformation per pass is controlled at 12% to obtain a Φ16 mm rolled bar.

[0103] Step Five: Hold the rolled bar at 780 °C for 1 h and then quickly water-cool it for quenching.

[0104] Step 6: Continuously cold-roll the rolled bars using a cold-rolling device, with a single-pass deformation of 8-10%. After the deformation reaches 40%-45%, perform intermediate annealing with an annealing regime of 650°C for 1 h. After repeating this cycle multiple times, obtain a Φ12 mm ultrafine-grained bar blank.

[0105] Step 7: Keep the bar blank at 700°C for 0.5 h and then air-cool it to perform recrystallization annealing heat treatment.

[0106] Step 8: Cut the bar blank to a fixed length of 200 mm and perform equal-channel angular pressing. The processing temperature is 500°C, the corner angle is 120°, use molybdenum disulfide as a lubricant, the processing speed is between 2 mm / s, the bar blank rotates 90° clockwise after each pass through the die, and the number of processing passes is 8.

[0107] Step 9: Perform cold drawing on the equiaxed ultrafine-grained bar blank using a drawing device, with a single-pass deformation of 10-13%. Use a lubricating fluid for lubrication, perform intermediate annealing at 650°C for 1 h, and then perform cold drawing again. After repeating this cycle multiple times, obtain a Φ6 mm bar wire.

[0108] Step 10: Cut the bar wire to a fixed length of 600 mm per piece and use a slider straightening machine to straighten the wire. After straightening, the straightness is 0.4 mm / m.

[0109] Step 11: Keep the bar wire at 550°C for 40 min for annealing.

[0110] Step 12: Use a centerless grinder to remove the surface oxide layer of the annealed bar wire. The surface roughness of the bar wire is 0.56 μm.

[0111] Table 3 shows the mechanical property test results of the Φ6.0 mm titanium-zirconium alloy wire obtained in Example 3

[0112]

[0113] Example 4

[0114] In the titanium-zirconium alloy bar wire of this example, its mass percentage includes: Zr: 15.10%, C: 0.008%, O: 0.186%, N: 0.009%, H: 0.005%, Fe: 0.023%, and the balance is Ti.

[0115] The preparation method of the titanium-zirconium alloy bar wire in this example includes:

[0116] Step 1: Charge sponge titanium, sponge zirconium, and ZrO2 powder according to the composition of the titanium-zirconium alloy, and use vacuum consumable melting three times. The vacuum degree of the first melting is 4×10 -3 Pa, the working current is 6.0 kA, and the working voltage is 30 V; the vacuum degree of the second melting is 10-2 Pa, working current 6.0 kA, working voltage 30 V; the vacuum degree of the third melting is 10 -1 Pa, working current 8.0 kA, working voltage 30 V; a Φ280 mm Ti-Zr alloy ingot is obtained.

[0117] Step 2: At 900 °C, keep the ingot warm for 1.5 h, then perform free forging with a quick forging machine, and control the deformation amount per heat to 70%, obtaining a Φ120 mm forged blank.

[0118] Step 3: Keep the forged blank warm at 950 °C for 1.5 h and then quickly water-cool it for quenching.

[0119] Step 4: At 800 °C, keep the forged blank warm for 1.5 h, then perform rolling with a Y-type three-high continuous rolling mill, and control the deformation amount per pass to 13%, obtaining a Φ18 mm rolled bar.

[0120] Step 5: Keep the rolled bar warm at 80 °C for 1 h and then quickly water-cool it for quenching.

[0121] Step 6: Use a cold rolling device to continuously cold roll the rolled bar, with the single-pass deformation amount being 8-10%. After the deformation amount reaches 35%-45%, perform intermediate annealing, and the annealing regime is 700 °C, 1 h. After repeating this process multiple times, a Φ12 mm ultrafine-grained bar blank is obtained.

[0122] Step 7: Keep the bar blank warm at 680 °C for 0.5 h and then air-cool it for recrystallization annealing heat treatment.

[0123] Step 8: Cut the bar blank to a fixed length of 200 mm, perform equal-channel angular pressing, and obtain an equiaxed ultrafine-grained alloy bar blank. The processing temperature is 500 °C, the corner angle is 120°, use molybdenum disulfide as a lubricant, the processing speed is between 2 mm / s, the bar blank rotates 90° clockwise after each pass through the die, and the number of processing passes is 7.

[0124] Step 9: Use a drawing device to perform cold drawing on the equiaxed ultrafine-grained alloy bar blank at room temperature, with the single-pass deformation amount being 10%, use a lubricating fluid for lubrication, perform intermediate annealing at 600 °C for 1 h, and then perform cold drawing again. After repeating this process multiple times, a Φ7 mm bar wire is obtained.

[0125] Step 10: Cut each bar to a fixed length of 600 mm, and use a hyperbolic straightening machine to straighten the bar. After straightening, the straightness is 0.5 mm / m.

[0126] Step 11: Keep the bar wire warm at 600 °C for 40 min for annealing.

[0127] Step 12: Use a centerless grinder to remove the surface oxide layer from the annealed bar wire, and the surface roughness of the bar wire is 0.51 μm.

[0128] Table 4 shows the mechanical property test results of the Φ7.0mm titanium-zirconium alloy wire obtained in Example 4

[0129]

[0130] Comparative Example 1

[0131] In this comparative example, the titanium-zirconium alloy bar wire has the following mass percentages: Zr: 15.15%, C: 0.004%, O: 0.193%, N: 0.018%, H: 0.008%, Fe: 0.028%, and the balance is Ti.

[0132] The preparation method of the titanium-zirconium alloy bar wire in this comparative example includes:

[0133] Step 1: Charge sponge titanium, sponge zirconium, and ZrO2 powder according to the composition of the titanium-zirconium alloy, and carry out vacuum consumable melting four times. The vacuum degree of the first melting is 5×10 -3 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree of the second melting is 10 -2 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree of the third melting is 10 -1 Pa, the working current is 8.0 kA, and the working voltage is 30 V; the vacuum degree of the fourth melting is 10 -1 Pa, the working current is 7.5 kA, and the working voltage is 30 V; obtain a Φ260mm Ti-Zr alloy ingot.

[0134] Step 2: At 900 °C, hold the ingot for 2 h, and then carry out free forging using a quick forging machine. The deformation amount per heat is controlled at 60% to obtain a Φ120mm forging blank.

[0135] Step 3: Hold the forging blank at 900 °C for 1.5 h and air cool.

[0136] Step 4: At 800 °C, hold the forging blank for 1.5 h, and then roll it using a Y-type three-high continuous rolling mill. The deformation amount per pass is controlled at 13% to obtain a Φ12mm rolled bar.

[0137] Step 5: Hold the rolled bar at 780 °C for 1 h and air cool.

[0138] Step 6: Continuously cold roll the rolled bar using a cold rolling device. The single-pass deformation amount is 10%. After the deformation amount reaches 40%-45%, intermediate annealing is carried out. The annealing system is 650 °C, 1 h. After repeating this process many times, a Φ6mm ultrafine-grained bar blank is obtained.

[0139] Step 7: Keep the billet at 700°C for 0.5 h and then air cool it to conduct recrystallization annealing treatment.

[0140] Step 8: Cut the billet to a fixed length of 500 mm, cut it into blanks, and conduct equal-channel angular pressing to obtain an equiaxed ultrafine-grained alloy billet. The processing temperature is 400°C, the corner angle is 120°, molybdenum disulfide is used as a lubricant, the processing speed is between 5 mm / s, the billet rotates 90° clockwise after passing through the die each time, and the number of processing passes is 6.

[0141] Step 9: Use a drawing device to conduct cold drawing on the equiaxed ultrafine-grained alloy billet at room temperature. The single-pass deformation amount is 11-13%, lubricate it with a lubricating fluid, conduct intermediate annealing at 650°C for 1 h, and then conduct cold drawing again. After repeating this process many times, a Φ4 mm bar wire is obtained.

[0142] Step 10: Cut the bar wire to a fixed length of 1000 mm per piece, and use a slider straightening machine to straighten the bar wire. After straightening, the straightness is 0.3 mm / m.

[0143] Step 11: Keep the bar wire at 600°C for 40 min for annealing.

[0144] Step 12: Use a centerless grinder to remove the surface oxide layer of the annealed bar wire, and conduct polishing by wet polishing. The surface roughness of the bar wire is 0.4 μm.

[0145] Table 5 shows the mechanical property test results of the Φ4.0 mm titanium-zirconium alloy bar wire obtained in Comparative Example 1

[0146]

[0147] Comparative Example 2

[0148] In the titanium-zirconium alloy bar wire of this comparative example, its mass percentage includes: Zr: 15.15%, C: 0.004%, O: 0.193%, N: 0.018%, H: 0.008%, Fe: 0.028%, and the balance is Ti.

[0149] The preparation method of the titanium-zirconium alloy bar wire in this comparative example includes:

[0150] Step 1: Charge sponge titanium, sponge zirconium, and ZrO2 powder according to the composition of the titanium-zirconium alloy, and conduct vacuum consumable melting four times. The vacuum degree of the first melting is 5×10 -3 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree of the second melting is 10 -2 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree of the third melting is 10 -1Pa, working current 8.0 kA, working voltage 30 V; the vacuum degree of the fourth melting is 10 -1 Pa, working current 7.5 kA, working voltage 30 V; obtain a Φ260 mm Ti-Zr alloy ingot.

[0151] Step 2: At 900 °C, keep the ingot for 2 h, then perform free forging using a quick forging machine, and control the deformation amount per heat to 60% to obtain a Φ120 mm forging blank.

[0152] Step 3: Keep the forging blank at 900 °C for 1.5 h and then quickly water-cool it for quenching.

[0153] Step 4: At 800 °C, keep the forging blank for 1.5 h, then perform rolling using a Y-type three-high continuous rolling mill, and control the deformation amount per pass to 13% to obtain a Φ12 mm rolled bar.

[0154] Step 5: Keep the rolled bar at 780 °C for 1 h and then quickly water-cool it for quenching.

[0155] Step 6: Use a drawing device to perform cold drawing on the equiaxed ultrafine-grained alloy bar blank at room temperature, with the single-pass deformation amount being 11-13%. Use a lubricating fluid for lubrication, perform intermediate annealing at 650 °C for 1 h, and then perform cold drawing again. After repeating this process many times, obtain a Φ4 mm bar wire.

[0156] Step 7: Cut the bar wire to a fixed length of 1000 mm per piece, and use a slider straightening machine to straighten the bar wire. After straightening, the straightness is 0.3 mm / m.

[0157] Step 8: Keep the bar wire at 600 °C for 40 min for annealing.

[0158] Step 9: Use a centerless grinder to remove the surface oxide layer of the annealed bar wire, and perform polishing using a wet polishing method. The surface roughness of the bar wire is 0.4 μm.

[0159] Table 6 shows the mechanical property test results of the Φ4.0 mm titanium-zirconium alloy bar wire obtained in Comparative Example 2

[0160]

[0161] Comparative Example 3

[0162] In the titanium-zirconium alloy bar wire of this comparative example, its mass percentage includes: Zr: 15.15%, C: 0.004%, O: 0.193%, N: 0.018%, H: 0.008%, Fe: 0.028%, and the balance is Ti.

[0163] The preparation method of the titanium-zirconium alloy bar wire in this comparative example includes:

[0164] Step 1: Charge materials according to the composition of the titanium-zirconium alloy using titanium sponge, zirconium sponge, and ZrO2 powder. Conduct vacuum consumable melting four times. The vacuum degree for the first melting is 5×10 -3 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree for the second melting is 10 -2 Pa, the working current is 5.5 kA, and the working voltage is 30 V; the vacuum degree for the third melting is 10 -1 Pa, the working current is 8.0 kA, and the working voltage is 30 V; the vacuum degree for the fourth melting is 10 -1 Pa, the working current is 7.5 kA, and the working voltage is 30 V; obtain a Φ260 mm Ti-Zr alloy ingot.

[0165] Step 2: At 900 °C, keep the ingot warm for 2 h, then conduct free forging using a quick forging machine, and control the deformation per heat at 60%, obtaining a Φ120 mm forged billet.

[0166] Step 3: Keep the forged billet warm at 900 °C for 1.5 h and then air-cool.

[0167] Step 4: At 800 °C, keep the forged billet warm for 1.5 h, then conduct rolling using a Y-type three-high continuous rolling mill, and control the deformation per pass at 13%, obtaining a Φ12 mm rolled bar.

[0168] Step 5: Keep the rolled bar warm at 780 °C for 1 h and then air-cool.

[0169] Step 6: Use a drawing device to conduct cold drawing on the equiaxed ultrafine-grained alloy bar blank at room temperature. The single-pass deformation is 11 - 13%. Use a lubricating fluid for lubrication, conduct intermediate annealing at 650 °C for 1 h, and then conduct cold drawing again. After repeating this process many times, obtain a Φ4 mm bar wire.

[0170] Step 7: Cut the bar wire into lengths of 1000 mm per piece, and use a slider straightening machine to straighten the bar wire. The straightness after straightening is 0.3 mm / m.

[0171] Step 8: Keep the bar wire warm at 600 °C for 40 min for annealing.

[0172] Step 9: Use a centerless grinder to remove the surface oxide layer of the annealed bar wire, and conduct polishing using a wet polishing method. The surface roughness of the bar wire is 0.4 μm.

[0173] Table 7 shows the mechanical property test results of the Φ4.0 mm titanium-zirconium alloy bar wire obtained in Comparative Example 3

[0174]

[0175] Compared with Example 1, Comparative Example 1 lacks the quenching process, and air cooling is used in Step 3 and Step 5; compared with Example 1, Comparative Example 2 lacks the cold rolling and severe plastic deformation processes; compared with Example 1, Comparative Example 3 lacks the quenching, cold rolling and severe plastic deformation processes. Compared with Examples 1-4, the tensile strength, yield strength, elongation after fracture, and reduction of area of the titanium-zirconium alloy bars and wires in Comparative Examples 1-3 are significantly reduced. Examples 1-4 are equiaxed ultrafine-grained titanium-zirconium alloy bars and wires prepared by using the preparation method of the medical equiaxed ultrafine-grained titanium-zirconium alloy bars and wires provided by the present invention. The titanium-zirconium alloy bars and wires in Examples 1-4 all have high tensile strength, yield strength, elongation after fracture, and reduction of area. The present invention introduces high-density defects into the material through severe plastic deformation and combines quenching heat treatment to regulate the microstructure of the alloy, realizes the preparation of equiaxed ultrafine-grained titanium-zirconium alloy bars and wires with high strength and plasticity and good fracture toughness, can obtain high strength and high fatigue strength, and meets the requirements of dental medical devices for raw materials.

[0176] The above-mentioned embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire, characterized in that: include: S1. Mix titanium sponge, zirconium sponge and zirconium dioxide according to a preset ratio and melt them into ingots; S2. After the ingot is kept at 850°C-1000°C, it is forged to obtain a forged billet; S3. The forging blank is subjected to a first quenching treatment; S4. The forging blank is kept at 770°C-840°C and then rolled to obtain a rolled strip; S5. The rolled strip is subjected to a second quenching treatment; S6. rolling the rolled strip at room temperature to obtain an ultrafine grained rod blank; S7. Recrystallization annealing treatment is performed on the ultrafine grained rod blank; S8. The ultrafine crystal rod blank is subjected to severe plastic deformation processing to obtain an equiaxed ultrafine crystal rod blank; S9. Drawing and reducing the equiaxed ultrafine grained rod blank at room temperature to obtain a rod wire; S10. Straightening the rod wire; S11. Annealing the rod wire; S12. Surface treatment is performed on the rods and wires to obtain qualified rods and wires.

2. The method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire according to claim 1, characterized in that: In step S1, vacuum self-consumption is used for 3-4 times of melting, and the vacuum degree is 10 -1 P-10 -3 Pa, a working current of 1kA-10kA, and a working voltage of 10V-50V to obtain the ingot.

3. The method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire according to claim 1, characterized in that: In step S2, the ingot is kept at 850°C-1000°C for 1h-5h, air-cooled, and free forged by a fast forging machine, with the deformation amount of each fire being not less than 50%, to obtain the forging blank.

4. The method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire according to claim 1, characterized in that: In step S4, the forging blank is kept at 770° C.-840° C. for 1 h-3 h, and then rolled by a horizontal rolling mill, with a single-pass deformation rate of less than 15%, to obtain the rolled strip.

5. The method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire according to claim 1, characterized in that: In step S6, a cold rolling mill is used to roll the strip at room temperature, and the deformation of a single pass is less than 15% and the total deformation is greater than 50%.

6. The method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire according to claim 1, characterized in that: The recrystallization annealing in step S7 includes keeping the ultrafine crystal rod blank at 600° C.-700° C. for 0.5 h-3 h and then air cooling it.

7. The method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire according to claim 1, characterized in that: The severe plastic deformation in S8 includes: performing equal-diameter angular extrusion on the ultrafine crystal rod blank through a die, using molybdenum disulfide as a lubricant, the equal-diameter angular extrusion processing speed is 1mm / s-10mm / s, the processing temperature is 400℃-500℃, and the processing number is 4-8 times.

8. The method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire according to claim 1, characterized in that: In S9, a roller mill drawing device is used to perform multiple drawing passes, and the deformation amount of a single pass is between 10% and 15%. Subsequently, stress relief annealing is performed, and the rod wire is obtained after multiple drawing passes.

9. The method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire according to claim 1, characterized in that: In S11, an annealing furnace is used to anneal the rods and wires at a temperature of 450° C. to 650° C. for a time of 20 min to 90 min.

10. The method for preparing medical equiaxed ultrafine-grained titanium-zirconium alloy rod and wire according to claim 1, characterized in that: In S12, a centerless grinder, a pickling polishing or a plasma polishing surface treatment equipment is used to perform surface treatment on the rod and wire to remove oxide scale on the surface of the rod and wire. The surface roughness of the qualified rod and wire is less than or equal to 0.8 μm.

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