Medical zirconium-niobium forged rod and preparation method thereof

Abstract

The invention belongs to the technical field of non-ferrous metal material forming, and particularly discloses a medical zirconium-niobium forged rod and a preparation method thereof.The preparation method adopts a multi-heating-number forging and quenching alternation process, the temperature is reduced in a gradient mode during forging each time, meanwhile, the forging ratio, the deformation amount and the deformation mode are dynamically adjusted, and therefore the medical zirconium-niobium forged rod is obtained. The method is used for refining the zirconium-niobium as-cast structure. According to the medical zirconium niobium forged rod prepared through the preparation method, the edge grain size reaches 12.5 grades or above, the core grain size reaches 13 grades or above, the difference value of the edge grain size and the core grain size is extremely small, meanwhile, on the basis that the grain size and the structure uniformity are guaranteed, good corrosion resistance is guaranteed, the problem that in the prior art, the product quality is not stable is effectively solved, and the medical zirconium niobium forged rod is suitable for industrial production. The medical zirconium-niobium forging rod with stable and reliable performance is provided for orthopedic implants, the risk of orthopedic surgery is reduced, and the increasing clinical requirements are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metal material forming, and particularly relates to a medical zirconium niobium forging bar and a preparation method thereof. Background Art

[0002] In the field of modern medicine, with the continuous development and progress of surgical operations, the performance requirements for medical implant materials are becoming increasingly stringent. As a key component of implants, the performance and quality of medical metal materials are directly related to the success rate of surgeries and the rehabilitation effects of patients.

[0003] Due to its many advantages such as non-toxicity, high strength, good corrosion resistance, excellent biocompatibility, and low magnetic susceptibility, zirconium niobium alloy has gradually become a research hotspot in the field of medical implant materials. Compared with traditional medical implant materials, zirconium niobium alloy has a lower elastic modulus, which can effectively reduce the joint stress shielding effect, and is thus more suitable for making medical implant joint prostheses, bone plates, screws, etc. To ensure good service performance of zirconium niobium alloy in medical scenarios, strict requirements are put forward for the grain size, uniformity, and corrosion resistance of its microstructure. Generally, it is expected that the grain size is not less than grade 10, and the microstructure is uniform and has good corrosion resistance.

[0004] Currently, the production processes of zirconium niobium alloy bars mainly include forging, extrusion, and forging combined with extrusion. Among them, although the extrusion process can make the material deformation more uniform and the metal flow more freely compared with the forging process, there are also the following problems: on the one hand, the processing cost of the extrusion process is relatively high and the material utilization rate is low, resulting in a significant increase in production costs; on the other hand, extrusion lines are easily formed during the extrusion process, making the material properties show large anisotropy, which is extremely unfavorable for the complex application environment of medical zirconium niobium alloy. Therefore, open die forging is still a better choice for preparing medical zirconium niobium forging bars.

[0005] However, the existing preparation of zirconium niobium forging bars by open die forging has the following defects: one is poor grain size control: it is difficult to stably obtain products that meet the requirement of grain size not less than grade 10, resulting in uneven product quality and unable to fully exert the performance advantages of zirconium niobium alloy; the other is insufficient tissue uniformity: the tissue differences between the edge and the core of the forging bar are relatively large, and the grain size difference often exceeds the expectation, which will affect the stability and reliability of the overall material performance and cannot meet the clinical requirements.

[0006] In view of this, this invention is specifically proposed. Summary of the Invention

[0007] The purpose of the present invention is to overcome the disadvantages of the above-mentioned existing technologies, and provides a medical zirconium-niobium forging bar and its preparation method, mainly used to solve the problem that when preparing medical zirconium-niobium forging bars by existing free forging, it is difficult to simultaneously meet the performance requirements in terms of grain size, tissue uniformity, corrosion resistance, etc., and the quality is unstable, unable to meet the clinical needs.

[0008] The purpose of the present invention is solved by the following technical solutions:

[0009] In the first aspect, the present invention provides a preparation method of a medical zirconium-niobium forging bar. The preparation method adopts a process of alternating multi-pass forging and quenching, and each time forging is carried out in a way of gradually reducing the temperature, and at the same time combines dynamic adjustment of the forging ratio, deformation amount and deformation mode to achieve the refinement of the as-cast structure of zirconium-niobium.

[0010] Furthermore, the preparation method specifically includes the following steps:

[0011] Step 1: One-pass forging

[0012] After the zirconium-niobium ingot after vacuum melting is held at 1010°C to 1050°C for 40 min to 50 min, three-upsetting and three-drawing forging is carried out.

[0013] Step 2: β quenching

[0014] After the forging blank obtained in Step 1 is held at 980°C to 1000°C for 40 min to 50 min, it is quenched.

[0015] Step 3: Two-pass forging

[0016] After the forging blank obtained in Step 2 is held at 920°C to 950°C for 40 min to 50 min, two-upsetting and two-drawing forging is carried out, and it is quenched after forging.

[0017] Step 4: Three-pass forging

[0018] After the forging blank obtained in Step 3 is held at 870°C to 900°C for 20 min to 30 min, two-upsetting and two-drawing forging is carried out, and it is quenched after forging.

[0019] Step 5: Four-pass forging

[0020] After the forging blank obtained in Step 4 is held at 720°C to 750°C for 20 min to 30 min, only drawing forging is carried out, and finally the target medical zirconium-niobium forging bar is obtained through machining treatment.

[0021] Furthermore, when carrying out three-upsetting and three-drawing forging in Step 1, the forging ratio is controlled between 2.4 and 2.6.

[0022] Further, in Steps II, III, and IV, the quenching is carried out by transferring the forging blank to a saturated brine tank, and the stirrer of the saturated brine tank needs to be turned on before quenching to prevent local temperature rise of the water temperature during quenching.

[0023] Further, when carrying out two-upsetting and two-drawing forging in Step III, the forging ratio is controlled between 1.7 and 1.9.

[0024] Further, when carrying out two-upsetting and two-drawing forging in Step IV, the forging ratio is controlled between 1.6 and 1.8.

[0025] Further, when carrying out drawing forging in Step V, the deformation amount is controlled between 20% and 30%.

[0026] In a second aspect, the present invention also provides a medical zirconium niobium forging bar, which is prepared based on the above-mentioned preparation method.

[0027] Further, the medical zirconium niobium forging bar is measured according to GB / T6394-2017, the grain size at the edge is above 12.5 levels, the grain size at the core is above 13 levels, and the difference in grain size between the edge and the core is less than or equal to 0.5 levels.

[0028] Further, the medical zirconium niobium forging bar is suitable for orthopedic implants.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention innovatively adopts a process of alternating multi-pass forging and quenching in the preparation of medical zirconium niobium forging bars, combined with gradient cooling and dynamically adjusting the forging ratio, deformation amount, and deformation method, fundamentally solving the problem that it is difficult to control the grain size and tissue uniformity. Specifically from the perspective of performance indicators, it is difficult for the prior art to stably meet the requirement that the grain size is not less than 10 levels, and the difference in grain size between the edge and the core is large. However, for the medical zirconium niobium forging bar prepared by the present invention, the grain size at the edge reaches above 12.5 levels, the grain size at the core reaches above 13 levels, and the difference in grain size between the edge and the core is extremely small (less than or equal to 0.5 levels), far exceeding the industry standard. At the same time, while ensuring the grain size and tissue uniformity, good corrosion resistance is also ensured, truly achieving the consideration of multiple performance requirements. In addition, in practical applications, the present invention effectively solves the problem of unstable product quality in the prior art, provides a medical zirconium niobium forging bar with stable and reliable performance for orthopedic implants, greatly improves the quality of medical implants, reduces the surgical risk, brings better treatment effects and rehabilitation experiences for patients, and strongly promotes the technological progress in the field of medical implant materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, and are used together with the specification to explain the principles of the present invention.

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 is a flowchart of the preparation method of the medical zirconium-niobium forging bar of the present invention;

[0034] Figure 2 is a metallographic microstructure diagram of the medical Zr-2.5Nb alloy forging bar with a specification of φ110mm prepared in Example 1 of the present invention; where: (a) Edge part: 5mm from the outer surface; (b) Core part: 50mm from the outer surface;

[0035] Figure 3 is the surface morphology diagram of the medical Zr-2.5Nb alloy forging bar with a specification of φ110mm prepared in Example 1 of the present invention after 3-day corrosion;

[0036] Figure 4 is a metallographic microstructure diagram of the medical Zr-2.5Nb alloy forging bar with a specification of φ180mm prepared in Example 2 of the present invention; where: (a) Edge part: 5mm from the outer surface; (b) Middle part: 40mm from the outer surface; (c) Core part: 85mm from the outer surface;

[0037] Figure 5 is the surface morphology diagram of the medical Zr-2.5Nb alloy forging bar with a specification of φ180mm prepared in Example 2 of the present invention after 3-day corrosion. Specific Embodiments

[0038] Here, the exemplary embodiments will be described in detail. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. On the contrary, they are only examples consistent with some aspects of the present invention detailed in the appended claims.

[0039] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0040] As Figure 1 shown, the preparation method of the medical zirconium-niobium forging bar provided by the present invention specifically includes the following steps:

[0041] Step 1. One-pass forging: After holding the vacuum-melted zirconium-niobium ingot at 1010°C to 1050°C for 40 minutes to 50 minutes, perform three-upsetting and three-drawing forging, and control the forging ratio between 2.4 and 2.6;

[0042] Step 2. β quenching: After holding the forging blank obtained from one-pass forging at 980°C to 1000°C for 40 min to 50 min, immediately (within 15 s) transfer it to a saturated brine tank with a stirrer turned on for quenching;

[0043] Step 3. Second-pass forging: After holding the forging blank after β quenching at 920°C to 950°C for 40 min to 50 min, perform two-upsetting and two-drawing forging, control the forging ratio between 1.7 and 1.9, and immediately transfer it to a saturated brine tank with a stirrer turned on for quenching after forging;

[0044] Step 4. Third-pass forging: After holding the forging blank obtained from the second-pass forging at 870°C to 900°C for 20 min to 30 min, perform two-upsetting and two-drawing forging, control the forging ratio between 1.6 and 1.8, and quickly transfer it to a saturated brine tank with a stirrer turned on for quenching after forging;

[0045] Step 5. Fourth-pass forging: After holding the forging blank obtained from the third-pass forging at 720°C to 750°C for 20 min to 30 min, only perform drawing forging, control the deformation amount between 20% and 30%, and finally obtain the target medical zirconium niobium forging bar through machining.

[0046] In order to further verify the efficacy of the preparation method of the present invention, the present inventor conducted the following specific tests:

[0047] Example 1

[0048] The embodiment of the present invention provides a preparation method of a medical zirconium niobium forging bar for preparing a medical Zr-2.5Nb alloy forging bar with a specification of φ110 mm. The specific preparation process is as follows:

[0049] 1) Heat the box-type resistance furnace to 1050°C. After the temperature is stable, load the Zr-2.5Nb ingot obtained by vacuum melting and qualified by spectral analysis and non-destructive testing into the furnace. Start timing after the furnace temperature is stable. After holding for 40 min, perform one-pass cogging forging in a three-upsetting and three-drawing manner, and control the forging ratio between 2.4 and 2.6;

[0050] 2) Heat the box-type resistance furnace to 1000°C. After the temperature is stable, load the forging blank obtained in step 1) into the furnace. Start timing after the furnace temperature is stable. Hold for 40 min, and immediately (within 15 s) transfer it to a saturated brine tank after taking it out of the furnace. The saturated brine tank needs to turn on the stirrer in advance to prevent the local water temperature from rising during quenching;

[0051] 3) Heat the box-type resistance furnace to 950 °C. After the temperature stabilizes, load the forging blank obtained in step 2) into the furnace. Start timing when the furnace temperature stabilizes. After holding for 40 min, perform free forging for the second heating. Adopt the method of two upsetting and two drawing, and control the forging ratio between 1.7 and 1.9. After forging to the size, immediately transfer it to a saturated brine tank. The saturated brine tank needs to start the stirrer in advance to prevent local temperature rise of the water temperature during quenching;

[0052] 4) Heat the box-type resistance furnace to 900 °C. After the temperature stabilizes, load the forging blank obtained in step 3) into the furnace. Start timing when the furnace temperature stabilizes. After holding for 20 min, perform free forging for the third heating. Adopt the method of two upsetting and two drawing, and control the forging ratio between 1.6 and 1.8. After forging to the size, immediately transfer it to a saturated brine tank. The saturated brine tank needs to start the stirrer in advance to prevent local temperature rise of the water temperature during quenching;

[0053] 5) Heat the box-type resistance furnace to 750 °C. After the temperature stabilizes, load the forging blank obtained in step 4) into the furnace. Start timing when the furnace temperature stabilizes. After holding for 20 min, perform free forging for the fourth heating. Adopt the method of only drawing without upsetting. To ensure the dimensional accuracy after forging and reduce the removal amount of oxide scale, control the deformation amount of the final forging heating between 20% and 30%;

[0054] 6) Cut the obtained φ110 mm medical zirconium niobium forging bar according to the technical requirements, and perform machining on the outer surface of the forging bar to remove oxide scale and forging defects. In addition, take samples from the ends of the forging bar.

[0055] Example 2

[0056] The embodiment of the present invention provides a preparation method of a medical zirconium niobium forging bar for preparing a medical Zr-2.5Nb alloy forging bar with a specification of φ180 mm. The specific preparation process is as follows:

[0057] 1) Heat the box-type resistance furnace to 1010 °C. After the temperature stabilizes, load the Zr-2.5Nb ingot obtained by vacuum melting and qualified by spectral analysis and non-destructive testing into the furnace. Start timing when the furnace temperature stabilizes. After holding for 50 min, perform cogging forging for the first heating. Adopt the method of three upsetting and three drawing, and control the forging ratio between 2.4 and 2.6;

[0058] 2) Heat the box-type resistance furnace to 980 °C. After the temperature stabilizes, load the forging blank obtained in step 1) into the furnace. Start timing when the furnace temperature stabilizes. After holding for 50 min, transfer it to a saturated brine tank immediately (within 15 s) after taking out of the furnace. The saturated brine tank needs to start the stirrer in advance to prevent local temperature rise of the water temperature during quenching;

[0059] 3) Heat the box-type resistance furnace to 920 °C. After the temperature stabilizes, load the forging blank obtained in step 2) into the furnace. Start timing when the furnace temperature stabilizes. After holding for 50 min, perform free forging for the second heat treatment. Adopt the method of two upsetting and two drawing, and control the forging ratio between 1.7 and 1.9. After forging to the required size, immediately transfer it to a saturated brine tank. The stirrer of the saturated brine tank needs to be started in advance to prevent local temperature rise of the water temperature during quenching.

[0060] 4) Heat the box-type resistance furnace to 870 °C. After the temperature stabilizes, load the forging blank obtained in step 3) into the furnace. Start timing when the furnace temperature stabilizes. After holding for 30 min, perform free forging for the third heat treatment. Adopt the method of two upsetting and two drawing, and control the forging ratio between 1.6 and 1.8. After forging to the required size, immediately transfer it to a saturated brine tank. The stirrer of the saturated brine tank needs to be started in advance to prevent local temperature rise of the water temperature during quenching.

[0061] 5) Heat the box-type resistance furnace to 720 °C. After the temperature stabilizes, load the forging blank obtained in step 4) into the furnace. Start timing when the furnace temperature stabilizes. After holding for 30 min, perform free forging for the fourth heat treatment. Adopt the method of only drawing without upsetting. To ensure the dimensional accuracy after forging and reduce the removal amount of oxide scale, the deformation amount of the final forging heat treatment is controlled between 20% and 30%.

[0062] 6) Cut the obtained φ180 mm medical zirconium niobium forging bar according to the technical requirements, and perform machining on the outer surface of the forging bar to remove oxide scale and forging defects. In addition, sample the end of the forging bar.

[0063] Example 3

[0064] An embodiment of the present invention provides a preparation method of a medical zirconium niobium forging bar for preparing a medical Zr-2.5Nb alloy forging bar with a specification of φ150 mm. The specific preparation process is as follows:

[0065] 1) Heat the box-type resistance furnace to 1030 °C. After the temperature stabilizes, load the Zr-2.5Nb ingot obtained by vacuum melting and qualified by spectral analysis and non-destructive testing into the furnace. Start timing when the furnace temperature stabilizes. After holding for 45 min, perform cogging forging for the first heat treatment. Adopt the method of three upsetting and three drawing, and control the forging ratio between 2.4 and 2.6.

[0066] 2) Heat the box-type resistance furnace to 990 °C. After the temperature stabilizes, load the forging blank obtained in step 1) into the furnace. Start timing when the furnace temperature stabilizes. After holding for 45 min, immediately transfer it to a saturated brine tank within 15 s after taking out of the furnace. The stirrer of the saturated brine tank needs to be started in advance to prevent local temperature rise of the water temperature during quenching.

[0067] 3) Heat the box-type resistance furnace to 930 °C. After the temperature stabilizes, load the forging blank obtained in step 2) into the furnace. Start timing after the furnace temperature stabilizes. After holding for 45 minutes, perform free forging for the second heat treatment, using the method of two upsetting and two drawing, and control the forging ratio between 1.7 and 1.9. After forging to the required size, immediately transfer it to a saturated brine tank. The stirrer of the saturated brine tank needs to be started in advance to prevent local temperature rise of the water temperature during quenching.

[0068] 4) Heat the box-type resistance furnace to 880 °C. After the temperature stabilizes, load the forging blank obtained in step 3) into the furnace. Start timing after the furnace temperature stabilizes. After holding for 25 minutes, perform free forging for the third heat treatment, using the method of two upsetting and two drawing, and control the forging ratio between 1.6 and 1.8. After forging to the required size, immediately transfer it to a saturated brine tank. The stirrer of the saturated brine tank needs to be started in advance to prevent local temperature rise of the water temperature during quenching.

[0069] 5) Heat the box-type resistance furnace to 730 °C. After the temperature stabilizes, load the forging blank obtained in step 4) into the furnace. Start timing after the furnace temperature stabilizes. After holding for 25 minutes, perform free forging for the fourth heat treatment, using the method of only drawing without upsetting. To ensure the dimensional accuracy after forging and reduce the removal amount of oxide scale, the deformation amount of the final forging heat treatment is controlled between 20% and 30%.

[0070] 6) Cut the obtained medical zirconium-niobium forging bar with a diameter of 150 mm according to the technical requirements, and perform machining on the outer surface of the forging bar to remove oxide scale and forging defects. In addition, samples are taken from the ends of the forging bar.

[0071] To verify the performance of the forging bars prepared by the preparation process of the present invention, the inventors respectively carried out metallographic structure observation and corrosion performance testing on the medical zirconium-niobium alloy forging bars prepared in Examples 1-2. The test results are as follows:

[0072] Metallographic structure observation: The process of preparing the metallographic specimen is as follows. Use a wire cutting machine to cut the end of the forging bar into appropriate sizes, grind it successively with sandpapers of different grits, then polish it with a polishing machine, and finally perform corrosion. Observe it with a metallographic microscope. The metallographic microstructure of Example 1 is as Figure 2 shown. According to the GB / T6394-2017 standard, the grain size is rated. The grain size rating of the edge part is 12.5 levels, the grain size rating of the core part is 13 levels, and the difference in grain size between the edge part and the core part is only 0.5 levels. The metallographic microstructure of Example 2 is as Figure 4 shown. According to the GB / T6394-2017 standard, the grain size is rated. The grain size ratings of the edge part, the middle part and the core part are all 13 levels.

[0073] Corrosion performance test: According to ASTM G2, the forged bars sampled from Examples 1-2 were respectively corroded for 3 days in a steam environment at 400 °C (pressure 10.3 MPa). The results were as follows: The surface morphology of the forged bar of Example 1 was as shown in Figure 3 , and the measured corrosion weight gain was 20.3 mg / dm 2 ; The surface morphology of the forged bar of Example 2 was as shown in Figure 5 , and the measured corrosion weight gain was 22.8 mg / dm 2 ; The above test results all meet the technical requirements. Compared with similar products, the forged bars prepared by the present invention have a smaller corrosion weight gain, indicating that they have better corrosion resistance, which is of great significance for the long-term use of medical zirconium-niobium forged bars in the human body environment, can effectively extend their service life, and reduce the potential risks caused by corrosion.

[0074] The above are only specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0075] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A method for preparing a medical zirconium-niobium forged rod, characterized in that: The preparation method adopts a process of alternating multiple forging and quenching, and reduces the temperature in a gradient manner during each forging, while dynamically adjusting the forging ratio, deformation amount and deformation mode, so as to achieve the refinement of the zirconium-niobium cast structure.

2. The method for preparing the medical zirconium-niobium forged rod according to claim 1, characterized in that: The preparation method specifically comprises the following steps: Step 1: First-time forging After vacuum melting, the zirconium-niobium ingot is kept at 1010°C to 1050°C for 40min to 50min, and then subjected to three-upsetting and three-drawing forging; Step 2: β Quenching The forging blank obtained in step 1 is kept at 980°C to 1000°C for 40min to 50min and then quenched; Step 3: Secondary Forging The forging blank obtained in step 2 is kept at 920°C to 950°C for 40min to 50min, and then subjected to double upsetting and double drawing forging, and quenched after forging; Step 4: Three-fire forging The forging blank obtained in step 3 is kept at 870°C to 900°C for 20min to 30min, and then subjected to double upsetting and double drawing forging, and quenched after forging; Step 5: Four-fire forging The forging blank obtained in step 4 is kept at 720° C. to 750° C. for 20 min to 30 min, then only subjected to drawing forging, and finally subjected to machining to obtain the target medical zirconium-niobium forged rod.

3. The method for preparing the medical zirconium-niobium forged rod according to claim 2, characterized in that: In the step 1, when performing three-upsetting and three-drawing forging, the forging ratio is controlled between 2.4 and 2.

6.

4. The method for preparing the medical zirconium-niobium forged rod according to claim 2, characterized in that: In steps 2, 3 and 4, the quenching is carried out by transferring the forging blank to a saturated brine tank, and the agitator of the saturated brine tank needs to be turned on before quenching to prevent the water temperature from rising locally during the quenching process.

5. The method for preparing the medical zirconium-niobium forged rod according to claim 2, characterized in that: In the step 3, when performing two-upsetting and two-drawing forging, the forging ratio is controlled between 1.7 and 1.

9.

6. The method for preparing the medical zirconium-niobium forged rod according to claim 2, characterized in that: In the step 4, when performing two-upsetting and two-drawing forging, the forging ratio is controlled between 1.6 and 1.

8.

7. The method for preparing the medical zirconium-niobium forged rod according to claim 2, characterized in that: In the step 5, when the drawing forging is performed, the deformation amount is controlled between 20% and 30%.

8. A medical zirconium-niobium forged rod, characterized in that: The medical zirconium-niobium forged rod is prepared based on the preparation method described in any one of claims 1 to 7.

9. The medical zirconium-niobium forged rod according to claim 8, characterized in that: The medical zirconium-niobium forged rod is measured according to GB / T6394-2017, the grain size of the edge is above level 12.5, the grain size of the core is above level 13, and the difference between the grain size of the edge and the core is less than or equal to level 0.

5.

10. The medical zirconium-niobium forged rod according to claim 8, characterized in that: The medical zirconium-niobium forged rod is suitable for orthopedic implants.

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