Preparation method of medical high-strength zirconium-niobium alloy bar

Abstract

The invention belongs to the field of medical zirconium-niobium alloy processing, and particularly relates to a preparation method of a medical high-strength zirconium-niobium alloy bar. The zirconium-niobium alloy comprises the following chemical components in percentage by mass: 2.0-3.0% of Nb, less than or equal to 0.2% of O, less than or equal to 0.01% of Hf, less than or equal to 0.02% of C, less than or equal to 0.15% of Fe and the balance of Zr. The method comprises the following steps: firstly, selecting nuclear-grade sponge zirconium as a raw material, adding a small amount of pure niobium or zirconium-niobium alloy and zirconium dioxide, and smelting through a vacuum consumable electric arc furnace to obtain a forged blank; then homogenizing heat treatment is carried out, the heat treatment temperature is 900-1000 DEG C, heat preservation is carried out for 2-10 hours, and air cooling is carried out; then multi-heating-number forging is conducted at the temperature of 800-950 DEG C, the forging deformation of each heating number is controlled to be 20%-80%, and the final forging temperature of each heating number is not lower than 600 DEG C; and finally straightening and polishing. Qualified zirconium-niobium alloy bars can be produced, and qualified raw materials are provided for manufacturing orthopedic medical instruments.

Description

Technical Field

[0001] The present invention belongs to the field of medical zirconium-niobium alloy processing, and specifically relates to a preparation method of a high-strength zirconium-niobium alloy rod for medical use. Background Art

[0003] Artificial hip joint prostheses mainly consist of a femoral stem, a femoral head, an acetabular cup, and a liner. According to the different materials of the artificial femoral head and acetabular liner, the friction interfaces are mainly divided into metal-on-metal, metal-on-polyethylene, ceramic-on-polyethylene, and ceramic-on-ceramic. Currently, ceramic-on-ceramic is the interface with the lowest wear rate, and due to its inherent biocompatibility, the probability of inflammatory reactions in the surrounding tissues caused by its wear particles is the lowest, which can effectively reduce the occurrence of osteolysis around the prosthesis and aseptic loosening after surgery. However, ceramics themselves have high brittleness and weak bending resistance. Improper placement of the prosthesis easily leads to the prosthesis being stressed beyond the load range, resulting in fragmentation.

[0004] Zirconium-niobium alloy (Zr-2.5Nb) is one of the metal materials with the best biocompatibility and is a new generation of artificial joint ball head material. After machining the joint prosthesis, the surface is oxidized to form a ZrO2 ceramic layer, so that the surface of the prosthesis has the smoothness and wear resistance of ceramic materials, while the matrix has high fatigue strength and high toughness, which can avoid the risk of fragility of ceramic components. In addition, the price of this kind of material ball head is only half of that of ceramic ball heads, having a great price advantage. However, niobium in zirconium-niobium alloy has a high melting point and is prone to becoming high-density inclusions, and problems such as low uniformity of the structure and properties of domestic rods, a large reduction in dimensional accuracy after machining the ball head, and easy peeling of the surface zirconia ceramics have severely restricted the development and innovation of artificial joint products in China. Therefore, it is urgent to carry out the research and development of high-performance zirconium-niobium alloy materials and joint products. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of a high-strength zirconium-niobium alloy rod for medical use, and solve the problems in the prior art that niobium in zirconium-niobium alloy has a high melting point and is prone to becoming high-density inclusions, and the uniformity of the structure and properties is low, the dimensional accuracy is greatly reduced after machining the ball head, and the surface zirconia ceramics are easy to peel off.

[0006] In order to solve the processing problems of Zr-Nb alloy rods, the technical solution adopted by the present invention is:

[0007] A preparation method of a high-strength zirconium-niobium alloy rod for medical use, the chemical composition and mass percentage of the zirconium-niobium alloy are: Nb is 2.0% - 3.0%, O ≤ 0.2%, Hf ≤ 0.01%, C ≤ 0.02%, Fe ≤ 0.15%, and the balance is Zr;

[0008] The preparation method of the high-strength zirconium-niobium alloy rod for medical use includes the following steps:

[0009] Step 1: Prepare a Zr-Nb alloy ingot by vacuum consumable arc furnace melting.

[0010] Step 2: Perform homogenization treatment on the zirconium-niobium alloy ingot at a treatment temperature of 900 - 1000 °C.

[0011] Step 3: Perform cogging forging on the homogenized zirconium-niobium alloy ingot.

[0012] Step 4: Perform continuous hot forging to prepare bars of various specifications.

[0013] Step 5: Perform straightening annealing on the forged bars.

[0014] Step 6: Continue to perform surface centerless grinding on the straightened and annealed bars to prepare qualified bars.

[0015] In the preparation method of the high-strength zirconium-niobium alloy bar for medical use, in Step 1, small particle nuclear-grade sponge zirconium with a particle size of 3 - 12.7 mm, pure niobium or zirconium-niobium alloy, and zirconium dioxide compound are used for batching according to the alloy composition, and vacuum consumable arc furnace melting is adopted to obtain an ingot.

[0016] In the preparation method of the high-strength zirconium-niobium alloy bar for medical use, in Step 1, first, the vacuum consumable arc furnace adopts high-power deep molten pool melting technology with a power range of 500 - 1500 kW·h / t, a molten pool depth of 500 - 800 mm, and a time of 1 - 4 hours; then, the vacuum consumable arc furnace adopts low-power shallow molten pool refining technology and arc stabilizing stirring technology with a power range of 300 - 800 kW·h / t, a molten pool depth of 300 - 600 mm, and a time of 2 - 8 hours.

[0017] In the preparation method of the high-strength zirconium-niobium alloy bar for medical use, in Step 2, the homogenization treatment is that the ingot is heated in the furnace to 900 - 1000 °C, held for 2 - 10 h, and air-cooled after being taken out of the furnace.

[0018] In the preparation method of the high-strength zirconium-niobium alloy bar for medical use, in Step 3, the selected cogging forging process is to heat to 900 - 1050 °C, hold for 3 - 8 hours, and the deformation amount is 20 - 80%.

[0019] In the preparation method of the high-strength zirconium-niobium alloy bar for medical use, in Step 4, the selected continuous hot forging process is to heat to 800 - 950 °C, hold for 1 - 5 hours for forging, the final forging temperature for each heat is above 600 °C, and it is forged into a bar after 1 - 10 heats, and the deformation amount for each heat is 20 - 80%.

[0020] For the preparation method of the high-strength zirconium-niobium alloy rod for medical use, in step five, a two-roll or multi-roll straightening machine is selected for straightening to ensure that the straightness is less than 0.03 mm.

[0021] For the preparation method of the high-strength zirconium-niobium alloy rod for medical use, in step five, the annealing temperature is 500 - 750 °C, the holding time is 1 - 4 hours, and it is cooled to room temperature in the furnace.

[0022] For the preparation method of the high-strength zirconium-niobium alloy rod for medical use, in step six, centerless grinding is to grind or turn the rod to meet the dimensional tolerance requirements.

[0023] The design concept of the present invention is:

[0024] Through the high-power deep molten pool smelting technology, the present invention eliminates the high-melting-point niobium inclusions; through the low-power shallow molten pool refining technology and the stable arc stirring technology, the composition uniformity of the zirconium-niobium alloy ingot is improved; combined with multi-pass high-temperature forging and heat treatment processes, the grain size, texture distribution and residual stress of the zirconium-niobium alloy are refined, significantly improving its mechanical properties and the ball head processing accuracy.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0026] 1. The present invention provides a preparation method of a high-strength zirconium-niobium alloy rod for medical use. Through this method, qualified rod products can be produced, providing qualified raw materials for orthopedic medical devices.

[0027] 2. The raw materials of the present invention have high purity. Through vacuum consumable arc furnace smelting, the composition uniformity of the alloy can be effectively controlled.

[0028] 3. By adopting the preparation method provided by the present invention, the production process is easy to operate, the required equipment is simple, and batch production of qualified zirconium-niobium alloy rod wires with a specification of Φ3 - Φ80 mm can be realized. Specific embodiments

[0029] In the specific implementation process, the present invention first selects nuclear-grade sponge zirconium as the raw material, adds a small amount of pure niobium or zirconium-niobium alloy and zirconium dioxide, and obtains a forging blank through vacuum consumable arc furnace smelting; then carries out homogenization heat treatment, and the heat treatment temperature regime is 900 °C - 1000 °C, the holding time is 2 hours - 10 hours, and it is air-cooled; subsequently, multi-pass forging is carried out at 800 - 950 °C, the forging deformation amount per pass is controlled at 20% - 80%, and the final forging temperature per pass is not lower than 600 °C; finally, straightening and grinding are carried out.

[0030] Next, the present invention will be further described in conjunction with embodiments.

[0031] Example 1

[0032] In this embodiment, the preparation method of the Zr-Nb alloy rod is as follows:

[0033] Step 1: using small-particle nuclear-grade sponge zirconium with a particle size of 3 to 12.7 mm, pure Nb chips, and zirconium dioxide compounds, batching as required, pressing electrodes, and melting in a vacuum consumable arc furnace to obtain a Zr-Nb alloy ingot;

[0034] First, the vacuum consumable arc furnace adopts high-power deep melt pool melting technology with a power of 1200kW·h / t, a melt pool depth of 600mm, and a time of 3 hours; then, the vacuum consumable arc furnace adopts low-power shallow melt pool refining technology and stable arc stirring technology with a power of 350kW·h / t, a melt pool depth of 350mm, and a time of 5 hours.

[0035] The chemical composition and mass percentage of the Zr-Nb alloy ingot are: Nb is 2.2%, O is 0.15%, Hf is 0.004%, C is 0.013%, Fe is 0.09%, and the balance is Zr.

[0036] Step 2: homogenize the zirconium-niobium alloy ingot, heat the ingot to 980°C in the furnace, keep it warm for 8 hours, and air-cool it to room temperature after it is taken out of the furnace;

[0037] Step 3: Forging the homogenized zirconium-niobium alloy ingot, heating it to 1000° C., keeping it warm for 5 hours, forging it into a square billet with a cross-sectional size of 300×300 mm, and a deformation amount of 60%;

[0038] Step 4: Continuous high temperature forging is performed, the temperature is raised to 900°C, and the forging is started after being kept at this temperature for 3 hours. The square billet after being opened is forged for 5 times, the forging size is Φ65mm, the deformation amount of each time is controlled at 40-50%, and the final forging temperature of each time is 650°C;

[0039] Step 5: Straighten and anneal the forged bars. Use a two-roll straightening machine to straighten the bars to ensure that the curvature is less than 0.03 mm. The annealing temperature is 630°C, the holding time is 2 hours, and the bars are cooled to room temperature with the furnace.

[0040] Step 6: Continue to perform centerless grinding on the surface of the straightened and annealed bars to produce qualified bars with a finished size of Φ61.0 mm.

[0041] Table 1 shows the mechanical properties of the Φ61 mm Zr-Nb alloy rod prepared in Example 1

[0042] Sample number Tensile strength Rm, MPa <![CDATA[Yield strength Rp 0.2 , MPa]]> Elongation A, % Specimen 1 570 385 24.0 Specimen 2 576 386 27.0

[0043] Example 2

[0044] In this embodiment, the preparation method of the Zr-Nb alloy rod is as follows:

[0045] Step 1: Use small particle nuclear-grade sponge zirconium with a particle size of 3 - 12.7 mm, pure Nb chips, and zirconium dioxide compounds to prepare the ingredients according to requirements, press the electrodes, and melt them using a vacuum consumable arc furnace to obtain a Zr-Nb alloy ingot.

[0046] First, the vacuum consumable arc furnace uses high-power deep-melting pool melting technology with a power of 1300 kW·h / t, a melting pool depth of 720 mm, and a time of 3.5 hours. Then, the vacuum consumable arc furnace uses low-power shallow-melting pool refining technology and arc-stabilizing stirring technology with a power of 480 kW·h / t, a melting pool depth of 410 mm, and a time of 5.5 hours.

[0047] The chemical composition and mass percentage of the Zr-Nb alloy are as follows: Nb is 2.4%, O is 0.10%, Hf is 0.07%, C is 0.016%, Fe is 0.14%, and the balance is Zr.

[0048] Step 2: Perform homogenization treatment on the zirconium-niobium alloy ingot. Heat the ingot in the furnace to 1000 °C, hold for 6 h, and then air-cool to room temperature after taking it out of the furnace.

[0049] Step 3: Perform cogging forging on the homogenized zirconium-niobium alloy ingot. Heat it to 980 °C, hold for 6 h, and cogging forge it into a square billet with a cross-sectional size of 280×280 mm, with a deformation amount of 50%.

[0050] Step 4: Perform continuous hot forging. Start forging after heating to 820 °C and holding for 5 hours. The square billet after cogging is forged through 5 passes, with a forging size of Φ60 mm. The deformation amount per pass is controlled at 45 - 55%, and the final forging temperature per pass is 600 °C.

[0051] Step 5: Straighten and anneal the forged bar. Use a two-roll straightening machine to straighten it to ensure that the straightness is less than 0.03 mm. The annealing temperature is 720 °C, the holding time is 2.5 hours, and then cool it to room temperature in the furnace.

[0052] Step 6: Continue to perform surface centerless grinding on the straightened and annealed bar to prepare a qualified bar with a finished size of Φ55.0 mm.

[0053] Table 2 shows the mechanical properties of the Φ55 mm specification Zr-Nb alloy bar prepared in Example 2

[0054]

[0055]

[0056] Example 3

[0057] In this example, the preparation method of the Zr-Nb alloy bar is as follows:

[0058] Step 1: Use small particle nuclear-grade sponge zirconium with a particle size of 3 - 12.7 mm, pure Nb chips, and zirconium dioxide compounds to prepare the ingredients according to requirements, press the electrodes, and melt them using a vacuum consumable arc furnace to obtain a Zr-Nb alloy ingot;

[0059] First, the vacuum consumable arc furnace uses high-power deep molten bath melting technology with a power of 1380 kW·h / t, a molten bath depth of 760 mm, and a time of 2 hours; then, the vacuum consumable arc furnace uses low-power shallow molten bath refining technology and arc stabilizing stirring technology with a power of 620 kW·h / t, a molten bath depth of 510 mm, and a time of 4 hours.

[0060] The chemical composition and mass percentage of the Zr-Nb alloy are as follows: Nb is 2.6%, O is 0.12%, Hf is 0.003%, C is 0.010%, Fe is 0.12%, and the balance is Zr.

[0061] Step 2: Homogenize the Zr-Nb alloy ingot. Heat the ingot in the furnace to 940 °C, hold for 10 h, and then air-cool to room temperature after taking it out of the furnace;

[0062] Step 3: Perform cogging forging on the homogenized Zr-Nb alloy ingot. Heat it to 1020 °C, hold for 5 h, and cogging forge it into a square billet with a cross-sectional size of 220×220 mm, with a deformation amount of 40%;

[0063] Step 4: Perform continuous hot forging. Start forging after heating to 870 °C and holding for 4 hours. The square billet after cogging is forged through 6 passes, with a forging size of Φ42 mm. The deformation amount per pass is controlled at 40 - 50%, and the final forging temperature per pass is 630 °C;

[0064] Step 5: Straighten and anneal the forged bar. Use a multi-roll straightening machine to straighten it to ensure that the straightness is less than 0.03 mm. The annealing temperature is 580 °C, the holding time is 1.5 hours, and then cool it to room temperature in the furnace;

[0065] Step 6: Continue to perform surface centerless grinding on the straightened and annealed bar to prepare a qualified bar with a finished size of Φ37.0 mm.

[0066] Table 3 shows the mechanical properties of the Φ37 mm Zr-Nb alloy bar prepared in Example 3

[0067] Sample number Rm, MPa <![CDATA[Rp 0.2 , MPa]]> A，％ Specimen 1 637 423 21.0 Specimen 2 638 427 20.5

[0068] Example 4

[0069] In this example, the preparation method of the Zr-Nb alloy bar is as follows:

[0070] Step 1: Use small particle nuclear-grade sponge zirconium with a particle size of 3 - 12.7 mm, pure Nb chips, and zirconium dioxide compounds to prepare the ingredients according to requirements, press the electrodes, and melt them using a vacuum consumable arc furnace to obtain a Zr-Nb alloy ingot;

[0071] First, the vacuum consumable arc furnace uses high-power deep molten pool melting technology with a power of 900 kW·h / t, a molten pool depth of 540 mm, and a time of 3.5 hours; then, the vacuum consumable arc furnace uses low-power shallow molten pool refining technology and stable arc stirring technology with a power of 700 kW·h / t, a molten pool depth of 560 mm, and a time of 6.5 hours.

[0072] The chemical composition and mass percentage of the Zr-Nb alloy are: Nb is 2.8%, O is 0.08%, Hf is 0.006%, C is 0.014%, Fe is 0.07%, and the balance is Zr.

[0073] Step 2: Homogenize the Zr-Nb alloy ingot. Heat the ingot in the furnace to 960°C, hold for 8 hours, and then air-cool to room temperature after taking it out of the furnace;

[0074] Step 3: Perform cogging forging on the homogenized Zr-Nb alloy ingot. Heat it up to 1040°C, hold for 5 hours, and cogging forge it into a square billet with a cross-sectional size of 220×220 mm, with a deformation amount of 40%;

[0075] Step 4: Perform continuous hot forging. Start forging after heating up to 910°C and holding for 2 hours. The square billet after cogging is forged through 6 passes, with a forging size of Φ29 mm. The deformation amount for each pass is controlled at 35 - 45%, and the final forging temperature for each pass is 700°C;

[0076] Step 5: Straighten and anneal the forged bar. Use a multi-roll straightening machine to straighten it to ensure that the straightness is less than 0.03 mm. The annealing temperature is 520°C, the holding time is 4 hours, and it is cooled to room temperature with the furnace;

[0077] Step 6: Continue to perform surface centerless grinding on the straightened and annealed bar to prepare a qualified bar with a finished size of Φ25.0 mm.

[0078] Table 4 shows the mechanical properties of the Φ25 mm specification Zr-Nb alloy bar prepared in Example 4

[0079] Sample number Rm, MPa <![CDATA[Rp 0.2 , MPa]]> A，％ Specimen 1 660 462 23.0 Specimen 2 658 459 23.5

[0080] The mechanical property test results of the examples show that due to the adoption of a matching homogenization treatment (temperature 940°C to 1000°C, holding time 6 to 10 h), cogging forging (temperature 980°C to 1040°C, holding time 5 to 6 h), continuous hot forging (temperature 820°C to 910°C, holding time 2 to 5 h), and annealing (annealing temperature 520 to 720°C, holding time 1.5 to 4 hours), the optimized process plan of the examples can obtain bars with Rm 547 to 660 MPa, Rp 0.2 379 to 462 MPa, and A 20.5 to 27.0%. Therefore, qualified zirconium niobium alloy bars can be produced by the present invention, providing qualified raw materials for manufacturing orthopedic medical devices.

[0081] The above are only the preferred embodiments of the present invention and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent variations made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a high-strength zirconium-niobium alloy rod for medical use, characterized in that: The chemical composition and mass percentage of the zirconium-niobium alloy are: Nb is 2.0% to 3.0%, O≤0.2%, Hf≤0.01%, C≤0.02%, Fe≤0.15%, and the balance is Zr; The method for preparing the medical high-strength zirconium-niobium alloy rod comprises the following steps: Step 1: preparing a Zr-Nb alloy ingot by smelting in a vacuum consumable arc furnace; Step 2: homogenizing the zirconium-niobium alloy ingot at a temperature of 900-1000° C. Step 3, forging the homogenized zirconium-niobium alloy ingot; Step 4: Perform continuous high-temperature forging to prepare bars of various specifications; Step 5: straightening and annealing the forged bars; Step 6: Continue to perform centerless grinding on the surface of the straightened and annealed bars to prepare qualified bars.

2. The method for preparing a high-strength zirconium-niobium alloy rod for medical use according to claim 1, characterized in that: In step 1, small-grained nuclear-grade sponge zirconium, pure niobium or zirconium-niobium alloy, and zirconium dioxide compound with a particle size of 3 to 12.7 mm are used, and the materials are prepared according to the alloy composition, and a vacuum consumable arc furnace is used for melting to obtain an ingot.

3. The method for preparing a high-strength zirconium-niobium alloy rod for medical use according to claim 1, characterized in that: In step one, first, the vacuum consumable arc furnace adopts high-power deep melt pool smelting technology with a power range of 500 to 1500 kW·h / t, a melt pool depth of 500 to 800 mm, and a time of 1 to 4 hours; then, the vacuum consumable arc furnace adopts low-power shallow melt pool refining technology and stable arc stirring technology with a power range of 300 to 800 kW·h / t, a melt pool depth of 300 to 600 mm, and a time of 2 to 8 hours.

4. The method for preparing a high-strength zirconium-niobium alloy rod for medical use according to claim 1, characterized in that: In step 2, the homogenization treatment is to heat the ingot to 900-1000°C with the furnace, keep it at this temperature for 2-10 hours, and air-cool it after it comes out of the furnace.

5. The method for preparing a high-strength zirconium-niobium alloy rod for medical use according to claim 1, characterized in that: In step three, the blank forging process is selected to heat to 900-1050° C., keep warm for 3-8 hours, and deform by 20-80%.

6. The method for preparing a high-strength zirconium-niobium alloy rod for medical use according to claim 1, characterized in that: In step 4, the continuous high temperature forging process is selected to heat up to 800-950°C and keep warm for 1-5 hours for forging. The final forging temperature of each fire is above 600°C. After 1-10 fires, the rod is forged, and the deformation of each fire is 20-80%.

7. The method for preparing a high-strength zirconium-niobium alloy rod for medical use according to claim 1, characterized in that: In step five, a two-roller or multi-roller straightening machine is used for straightening to ensure that the curvature is less than 0.03 mm.

8. The method for preparing a high-strength zirconium-niobium alloy rod for medical use according to claim 1, characterized in that: In step 5, the annealing temperature is 500-750° C., the holding time is 1-4 hours, and the furnace is cooled to room temperature.

9. The method for preparing a high-strength zirconium-niobium alloy rod for medical use according to claim 1, characterized in that: In step six, centerless grinding is to grind or turn the bar to meet the dimensional tolerance requirements.

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