TC4 alloy, preparation method thereof and application of TC4 alloy in preparation of medical thighbone and tibia component

Abstract

The invention relates to the technical field of alloy preparation, and particularly discloses a TC4 alloy, a preparation method thereof and application of the TC4 alloy in preparation of medical thighbone and tibia components. The preparation method of the TC4 alloy specifically comprises the following steps of raw material feeding, electron beam selective melting preparation forming, sand blasting, drying, hot isostatic pressing, heat treatment, grinding and polishing and quality detection. The parameter conditions of hot isostatic pressing are as follows: the temperature is raised to 900-940 DEG C at the temperature raising rate of 8-12 DEG C / min, the pressure is kept at 90-120 MPa, and the temperature and pressure are kept for 90-180 minutes; the parameter conditions of the heat treatment are as follows: first-stage heat preservation is performed for 30-120 minutes under the condition that the temperature is 700-900 DEG C, and then second-stage heat preservation is performed for 3-5 hours under the condition that the temperature is 400-600 DEG C; and argon is filled as protective gas in the whole process. By means of the technical scheme, the anti-fatigue performance of the TC4 alloy can be effectively improved, and the service time of the TC4 alloy thighbone and tibia assembly is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of alloy preparation, and in particular to a TC4 alloy and a preparation method thereof and an application thereof in the preparation of medical femoral tibial components. Background Art

[0002] Knee arthritis is the most common type of osteoarthritis. It is a disease based on degenerative pathological changes and mostly affects middle-aged and elderly people. At present, knee prosthesis replacement is often used to treat middle- and late-stage knee arthritis or joint pain and deformity caused by trauma. Metal parts in knee prostheses are mostly made of cobalt-chromium-molybdenum materials and TC4 alloy materials through casting, forging and machining. Cobalt-chromium-molybdenum materials have a high density, are much heavier than the original bone, and have poor proprioception; TC4 alloy materials have a low density, but machined TC4 alloy materials cannot quickly and accurately match the patient's original bone.

[0003] The latest 3D printing technology can form complex parts and improve material utilization, and is widely used in the field of orthopedic implant materials. Among them, the TC4 alloy prepared by electron beam selective melting 3D printing technology has a porous structure, which increases the contact area with the new bone and is more adaptable to the bone ingrowth of the new bone.

[0004] However, due to its own process characteristics, the TC4 alloy products prepared by electron beam selective melting still have a certain gap in tensile strength and fatigue resistance compared with the forged TC4 alloy machined products, which limits its application and development in clinical medicine.

[0005] Therefore, it is crucial to invent a process to improve the fatigue resistance of electron beam 3D printed TC4 alloy. Summary of the invention

[0006] In order to solve the above technical problems, the present application provides a TC4 alloy and a preparation method thereof and an application thereof in the preparation of medical femoral tibial components.

[0007] The present application provides a method for preparing a TC4 alloy, which specifically comprises the following steps in sequence: raw material feeding, electron beam selective melting preparation and molding, sandblasting, drying, hot isostatic pressing, heat treatment, grinding and polishing, and quality inspection; The parameters of the hot isostatic pressing are: heating to 900-940°C at a heating rate of 8-12°C / min, maintaining a pressure of 90-120MPa, and maintaining the temperature and pressure for 90-180min; The heat treatment parameters are: a first heat preservation period of 30-120 minutes at a temperature of 700-900° C., and a second heat preservation period of 3-5 hours at a temperature of 400-600° C.; argon is filled as a protective gas throughout the process.

[0008] The hot isostatic pressing and heat treatment in the technical solution provided in the present application can effectively reduce the internal porosity of the TC4 alloy, improve the density of the material, and reduce the stress concentration during high-cycle fatigue, thereby making the TC4 alloy exhibit good fatigue resistance.

[0009] Preferably, the TC4 alloy consists of the following components in mass percentage: iron ≤ 0.30, carbon ≤ 0.10, nitrogen ≤ 0.05, hydrogen ≤ 0.015, oxygen ≤ 0.20, aluminum 5.5-6.75, vanadium 3.5-4.5, and titanium balance.

[0010] Preferably, the parameters of the hot isostatic pressing are: heating to 910-930° C. at a heating rate of 9-11° C. / min, maintaining a pressure of 100-110 MPa, and maintaining the temperature and pressure for 100-140 min.

[0011] In a specific embodiment, the parameters of the hot isostatic pressing are: heating to 920° C. at a heating rate of 10° C. / min, maintaining a pressure of 105 MPa, and maintaining the temperature and pressure for 120 minutes.

[0012] Preferably, the heat treatment parameters are: first, heat preservation at 750-850°C for 50-100 min, then heat preservation at 450-550°C for 3.5-4.5 h; argon is filled as protective gas throughout the process.

[0013] In a specific embodiment, the heat treatment parameters are: first, a first insulation at a temperature of 800° C. for 75 minutes, and then a second insulation at a temperature of 500° C. for 4 hours; argon is filled as a protective gas throughout the process.

[0014] Preferably, in the parameter conditions of the heat treatment: the temperature of the first insulation stage = the temperature of the second insulation stage + (250-350° C.).

[0015] After experimental analysis, the applicant of the present application found that when the first insulation temperature is higher than the second insulation temperature (250-350°C), the fatigue resistance of the TC4 alloy can be further improved.

[0016] Preferably, the parameters of the electron beam selective melting preparation molding are: electron beam acceleration voltage is 50-70 kV, preheating temperature is 700-800 ° C; electron beam scanning speed is 2800-3200 mm / s, vacuum degree is maintained at (3.8-4.3) × 10 - 3 mBar.

[0017] Preferably, the parameters of the sandblasting are: a processing force of 0.1-1 MPa, and a processing time of 30-120 s.

[0018] This application utilizes sandblasting surface treatment to remove impurities such as oxides, pores, burrs, etc. on the alloy surface, improve the surface roughness of the TC4 alloy, provide a better foundation for subsequent hot isostatic pressing and heat treatment, and help improve the alloy's fatigue resistance.

[0019] In a second aspect, the present application provides a TC4 alloy, which is prepared using the above-mentioned preparation method.

[0020] In a third aspect, the present application provides the use of the above-mentioned TC4 alloy in the preparation of medical femoral tibial components.

[0021] In summary, the technical solution of this application has the following effects: In the process of preparing TC4 alloy, the present application performs hot isostatic pressing and two-stage heat preservation treatment on the TC4 alloy prepared by electron beam selective melting, strictly controls the process parameters of each stage, and reasonably performs matching optimization, which can effectively reduce the internal porosity of the TC4 alloy, improve the density of the material, and reduce stress concentration during high-cycle fatigue, thereby making the TC4 alloy exhibit good fatigue resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The metallographic structures of the TC4 alloys prepared in Example 3 and Comparative Example 9 are shown in FIG. 1 ; (a) is the TC4 alloy prepared in Comparative Example 9; and (b) is the TC4 alloy prepared in Example 3.

[0023] Figure 2 The stress-cycle number test result diagram of the fatigue performance of the TC4 alloys prepared in Example 3 and Comparative Example 9; wherein (a) is the TC4 alloy prepared in Comparative Example 9; and (b) is the TC4 alloy prepared in Example 3. DETAILED DESCRIPTION

[0024] The present application is further described in detail below in conjunction with examples, comparative examples and performance testing experiments. These examples should not be construed as limiting the scope of protection claimed in the present application. Example

[0025] Examples 1-5 Examples 1-5 respectively provide a method for preparing a TC4 alloy.

[0026] The difference between the above embodiments is that the parameter conditions of hot isostatic pressing are different, as shown in Table 1.

[0027] The preparation method of the TC4 alloy in the above embodiment is specifically as follows.

[0028] (1) Raw material charging: Alloy powder is prepared according to the following composition percentage by mass of TC4 alloy: 0.10% iron, 0.05% carbon, 6.0% aluminum, 4.0% vanadium, and the remainder titanium.

[0029] (2) Electron beam selective melting preparation: According to the three-dimensional geometric model designed by the drawing software, the TC4 alloy raw material alloy powder was prepared by electron beam selective melting. The electron beam acceleration voltage was 60 kV, and the powder layer was preheated with a 25 mA electron beam at a preheating temperature of 750 °C. The preheated powder layer was selectively melted and scanned, and the scanning speed of the electron beam was about 3000 mm / s. During the entire molding process, the vacuum degree of the molding chamber was maintained at 4.1×10 -3 mBar, and helium was used as the protective gas; then integrated 3D printing was performed under the protection of argon atmosphere to obtain TC4 alloy printed components.

[0030] (2) Sandblasting: The TC4 alloy printed component is sandblasted to remove the metal powder adhering to the surface; the sandblasting force is 0.5 MPa and the processing time is 75 s.

[0031] (3) Drying: The sandblasted TC4 alloy printing components are cleaned and dried at a drying temperature of 50°C.

[0032] (4) Hot isostatic pressing: The TC4 alloy printed components are subjected to hot isostatic pressing to eliminate the residual stress generated by the metal during the 3D printing process; the parameters of the hot isostatic pressing are shown in Table 1.

[0033] (5) Heat treatment: first keep the temperature at 800°C for 75 minutes, then keep the temperature at 500°C for 4 hours; fill with argon as a protective gas throughout the process.

[0034] (6) Grinding and polishing: The heat-treated TC4 alloy printed components are pre-treated by mechanical grinding and polishing to make the surface of the components smooth.

[0035] (7) Quality inspection: The mechanically polished samples are subjected to wire cutting, cold mounting, and etching with hydrofluoric acid and nitric acid aqueous solution, and quality inspection is performed.

[0036] Table 1 Parameters of hot isostatic pressing in Examples 1-5 and Comparative Examples 1-4 Embodiment 6-13 Examples 6-13 respectively provide a method for preparing a TC4 alloy.

[0037] The difference between the above embodiment and embodiment 3 is that the parameter conditions of the heat treatment are different, as shown in Table 2.

[0038] Table 2 Parameters of heat treatment in Examples 3, 6-13 and Comparative Examples 5-8 The other process parameters in the above embodiment are the same as those in embodiment 3.

[0039] Comparative Example Comparative Examples 1-4 Comparative Examples 1-4 respectively provide a method for preparing a TC4 alloy.

[0040] The difference between the comparative example and Example 3 is that the parameters of hot isostatic pressing are different, as shown in Table 1.

[0041] The other process parameters in the above comparative example are the same as those in Example 3.

[0042] Comparative Examples 5-8 Comparative Examples 5-8 respectively provide a method for preparing a TC4 alloy.

[0043] The difference between the comparative example and Example 3 is that the heat treatment parameters are different, as shown in Table 2.

[0044] The other process parameters in the above comparative example are the same as those in Example 3.

[0045] Comparative Example 9 Comparative Example 9 provides a method for preparing a TC4 alloy.

[0046] In this comparative example, no hot isostatic pressing and heat treatment steps were performed.

[0047] The other process parameters in this comparative example are the same as those in Example 3.

[0048] Performance testing (1) Morphology of TC4 alloy like Figure 1 Shown are metallographic structures of TC4 alloy, where (a) is the TC4 alloy prepared in Comparative Example 9; (b) is the TC4 alloy prepared in Example 3.

[0049] Depend on Figure 1It can be seen that the metallographic structure is mainly composed of α phase, and β phase exists between adjacent α phases. This is because the sample is rapidly cooled and solidified from above the β phase transformation point, forming a lamellar α phase, so the metallographic structure in both states is a lamellar α+β phase. In addition, the α phase lamellae of Example 3 after hot isostatic pressing and heat treatment are significantly thicker than the initial state. This is because the hot isostatic pressing temperature is set close to the β phase transformation point of the TC4 alloy (980℃±10℃) and two stages of insulation are performed, followed by furnace cooling. The thickness of the α+β phase lamellae inside the TC4 alloy after hot isostatic pressing and heat treatment is more uniform, and the number of holes is significantly reduced, indicating that the hot isostatic pressing and heat treatment processes mentioned in this application can significantly improve the internal microstructure of the TC4 alloy.

[0050] (3) Fatigue resistance of TC4 alloy The test samples prepared in the examples and comparative examples of the present application are all TC4 alloy femoral condyle samples after electron beam selective melting, so the fatigue performance standard for femoral condyle components is adopted. The fatigue performance of the femoral condyle in the tibia-femoral component of the knee joint is evaluated according to the group standards ASTM F3210M-22 and T / CSBME046-2022 "Closed Fatigue Test Method for Femoral Components of Total Knee Prosthesis".

[0051] Fatigue test loading conditions: At dry room temperature (23±5℃), apply a maximum load of 3000N-5100N to each sample, with an increase of 300N, and conduct a high-cycle fatigue test for 10 million times. If failure occurs during the test, the test will be terminated early. The fatigue test load ratio is 10:1 and the frequency is 10Hz.

[0052] The stress-cycle test results of the fatigue performance of TC4 alloy are shown in the figure Figure 2 As shown, (a) is the TC4 alloy prepared in Comparative Example 9; (b) is the TC4 alloy prepared in Example 3.

[0053] The anti-fatigue performance test results of Examples 1-13 and Comparative Examples 1-9 are shown in Table 3.

[0054] Table 3 Fatigue resistance of TC4 alloy in Examples 1-13 and Comparative Examples 1-9 from Figure 2It can be seen that the fatigue resistance of the TC4 alloy prepared in Comparative Example 9 is poor, and fatigue fracture begins to occur after only about 2.5 million cycles at 3300N, while the TC4 alloy prepared in Example 3 shows excellent fatigue resistance and can still maintain 10 million cycles without fracture under a loading force of 4800N. This is because in the process of preparing TC4 alloy by electron beam selective melting, the TC4 alloy powder is very likely to be heated unevenly and melted insufficiently during the heating process, resulting in pores inside the TC4 alloy. During the high-cycle fatigue cycle, these pores will form stress concentration points, resulting in fatigue fracture. The porosity inside the TC4 alloy after hot isostatic pressing and heat treatment in Example 3 is greatly reduced, the material density is improved, the thickness of the lamellar α+β phase layer is slightly increased, but the distribution is more uniform, reducing the stress concentration during the high-cycle fatigue process, and thus showing good fatigue resistance.

[0055] Combined with Table 3, by comparing the test results of the embodiment and the comparative example, it can be seen that in the process of preparing the TC4 alloy, the present application performs hot isostatic pressing and two-stage insulation treatment on the TC4 alloy prepared by electron beam selective melting, and strictly controls the process parameters of each stage, and reasonably performs matching optimization, so that the fatigue resistance of the TC4 alloy is greatly improved.

[0056] By comparing the test results of Examples 1-5 with Comparative Examples 1-4, it can be seen that the heating rate of hot isostatic pressing in Comparative Examples 1-2 is too slow or too fast, and the temperature of hot isostatic pressing in Comparative Examples 3-4 is too low or too high, and the fatigue resistance of the prepared TC4 alloy is poor. In contrast, the heating rate and insulation temperature of hot isostatic pressing are controlled to be heated to 900-940°C at a heating rate of 8-12°C / min, and a TC4 alloy with excellent fatigue resistance is obtained. Further, the present application controls the parameter conditions of hot isostatic pressing to: heating to 910-930°C at a heating rate of 9-11°C / min, maintaining a pressure of 100-110MPa, and maintaining heat and pressure for 100-140min.

[0057] By comparing the test results of Examples 3, 6-13 and Comparative Examples 5-8, it can be seen that Comparative Example 5 only uses one stage of heat preservation, the temperature of the first stage of heat preservation in Comparative Example 5 is relatively low, and the temperature of the second stage of heat preservation in Comparative Examples 6-7 is too low or too high, and the fatigue resistance of the prepared TC4 alloy is poor. In contrast, the embodiment of the present application first heats for 30-120 minutes at a temperature of 700-900°C, and then heats for 3-5 hours at a temperature of 400-600°C, and obtains a TC4 alloy with excellent fatigue resistance. Further, the present application chooses to heat for 50-100 minutes at a temperature of 750-850°C, and then heats for 3.5-4.5 hours at a temperature of 450-550°C, which further improves the fatigue resistance of the TC4 alloy.

[0058] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing TC4 alloy, characterized in that: Specifically, the following steps are carried out in sequence: raw material feeding, electron beam selective melting preparation and molding, sandblasting, drying, hot isostatic pressing, heat treatment, grinding and polishing, and quality inspection; The parameters of the hot isostatic pressing are: heating to 900-940°C at a heating rate of 8-12°C / min, maintaining a pressure of 90-120MPa, and maintaining the temperature and pressure for 90-180min; The heat treatment parameters are: a first heat preservation at a temperature of 700-900° C. for 30-120 minutes, and a second heat preservation at a temperature of 400-600° C. for 3-5 hours; argon is filled as a protective gas throughout the process.

2. The method for preparing the TC4 alloy according to claim 1, characterized in that: The TC4 alloy is composed of the following components in mass percentage: iron ≤ 0.30, carbon ≤ 0.10, nitrogen ≤ 0.05, hydrogen ≤ 0.015, oxygen ≤ 0.20, aluminum 5.5-6.75, vanadium 3.5-4.5, and titanium balance.

3. The method for preparing the TC4 alloy according to claim 1, characterized in that: The parameters of the hot isostatic pressing are: heating to 910-930° C. at a heating rate of 9-11° C. / min, maintaining a pressure of 100-110 MPa, and maintaining the temperature and pressure for 100-140 minutes.

4. The method for preparing the TC4 alloy according to claim 1, characterized in that: The heat treatment parameters are as follows: first, heat preservation at 750-850°C for 50-100 minutes, and then heat preservation at 450-550°C for 3.5-4.5 hours; argon is filled as protective gas throughout the process.

5. The method for preparing the TC4 alloy according to claim 1, characterized in that: In the parameter conditions of the heat treatment: the temperature of the first insulation stage = the temperature of the second insulation stage + (250-350°C).

6. The method for preparing the TC4 alloy according to claim 1, characterized in that: The parameters of the electron beam selective melting preparation molding are as follows: electron beam acceleration voltage is 50-70 kV, preheating temperature is 700-800°C; electron beam scanning speed is 2800-3200 mm / s, and vacuum degree is maintained at (3.8-4.3)×10 -3 mBar.

7. The method for preparing the TC4 alloy according to claim 1, characterized in that: The parameters of the sandblasting are as follows: the processing force is 0.1-1 MPa, and the processing time is 30-120 s.

8. The method for preparing the TC4 alloy according to claim 1, characterized in that: The drying temperature is 40-60°C.

9. A TC4 alloy, characterized in that: The TC4 alloy is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the TC4 alloy according to claim 9 in preparing medical femoral tibial components.

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