A TC4 titanium alloy orthopaedic prosthesis component, femoral stem and a heat treatment method thereof

Abstract

This invention relates to the field of orthopedic implant prosthesis technology, specifically disclosing a TC4 titanium alloy orthopedic prosthesis component, a femoral stem, and a heat treatment method thereof. The heat treatment method includes: S101, manufacturing the TC4 titanium alloy orthopedic prosthesis component using a spot-exposure laser 3D printing process to obtain a first component; S102, placing the first component in a vacuum heat treatment furnace for stress-relief annealing to obtain a second component; S103, heat-treating the second component using hot isostatic pressing, followed by cooling, to obtain a third component with an α / α'+β phase dual-state structure; S104, decomposing the residual metastable α' phase using a high-temperature solution treatment, and then using water quenching for rapid cooling to inhibit the regeneration of the α' phase, forming a fourth component with a fine-grained basket-like α+β phase structure; S105, using an aging process to eliminate the residual stress formed during the rapid water quenching process, to obtain a fifth component.

Description

Technical Field

[0001] This invention relates to the field of orthopedic implant prosthesis technology, and in particular to a TC4 titanium alloy orthopedic prosthesis component, a femoral stem, and a heat treatment method thereof. Background Technology

[0002] Artificial joint replacement surgery is often used to relieve patient pain, restore bone function, and improve patients' quality of life. For example, total hip replacement surgery is one of the most important and effective surgeries for treating end-stage diseases such as avascular necrosis of the femoral head, hip dysplasia, osteoarthritis of the hip, and rheumatoid arthritis.

[0003] Biologically fixed implants (solid and porous) have gained widespread use due to their advantages of good biocompatibility, excellent mechanical properties, and low post-implantation loosening rate. For example, artificial hip joint prostheses are artificial prostheses used in hip replacement surgery and joint reconstruction. An artificial hip joint generally consists of a femoral stem, femoral head, acetabular liner, and acetabular cup.

[0004] Existing orthopedic prostheses primarily utilize alloy materials for implantation. These alloys, including titanium alloys, bone molybdenum alloys, and tantalum alloys, are medical-grade metal materials with excellent biocompatibility and mechanical properties, making them commonly used materials for orthopedic implants. For example, the femoral stem assembly of a traditional artificial hip joint is forged and cast from TC4 titanium alloy, followed by machining. Since the femoral stem and proximal femoral medullary cavity are initially mechanically fixed through press fitting, and long-term mechanical stability is maintained through bone ingrowth, the proximal femoral stem is typically coated using plasma spraying to create a pure titanium (Ti) coating, a hydroxyapatite (HA) coating, or a Ti+HA double coating. However, the coating thickness is usually only about 50 micrometers, and there is a risk of coating detachment later on.

[0005] Laser 3D printing of alloy materials, such as titanium alloys, enables the integrated manufacturing of orthopedic prostheses, including the femoral stem and trabeculae. This reduces the number of manufacturing steps, allows for adjustable trabecular thickness (1-2 mm), and enables free adjustment of trabecular porosity, as well as the directional and orderly arrangement of trabecular units. Therefore, laser 3D printing of orthopedic prostheses is now widely used.

[0006] For example, patent application CN117204984A discloses a composite material 3D-printed orthopedic prosthesis and its preparation method, relating to the field of orthopedic medical devices. The 3D-printed orthopedic prosthesis includes a bone fusion end and an elastic material end. The bone fusion end includes a solid bone frame and a porous structure. The solid bone frame is filled with the porous structure, which is composed of multiple interconnected basic porous structural units, each of which is composed of several interconnected linkages. The solid bone frame and the porous structure are printed in one step using a metal 3D laser printing method. The elastic material end is fixedly connected to the bone fusion end and covers the porous structure. This invention discloses a 3D-printed orthopedic prosthesis that possesses both post-implantation stability and improved biocompatibility.

[0007] For example, patent application CN117598840A discloses a method for constructing a personalized lattice structure hip joint prosthesis based on 3D printing. The method includes: using medical modeling software to reverse engineer a patient's femoral CT data to obtain a femoral model; measuring the dimensions of the femoral model and using 3D modeling software to create a full hip joint prosthesis model; the full hip joint prosthesis model includes: a femoral head, a femoral stem, an acetabular cup, and a liner; the femoral stem is composed of a tetrahedral lattice structure; the full hip joint prosthesis model is converted to a new format and imported into topology optimization software, where material properties are assigned and boundary load conditions are applied; the topology optimization software performs lattice optimization on the femoral stem to obtain a personalized lattice structure hip joint prosthesis, which is then formed using laser selective melting technology. The prosthesis constructed using this method can meet the specific needs of patients with different body shapes and improve post-implantation stability.

[0008] For example, patent CN109009572B discloses a hip joint prosthesis stem and its manufacturing method, relating to the field of hip joint technology. The method includes: scanning the target hip joint using a CT scanner and establishing an initial solid model of the hip joint prosthesis stem based on femoral defect data and medullary canal longitudinal shape trend data; then, topologically optimizing the initial solid model of the hip joint prosthesis stem using preset pressure load data and medullary canal constraint load data to obtain an optimized solid model of the hip joint prosthesis stem; redesigning the optimized solid model of the hip joint prosthesis stem, filling the topology-removed parts with different porous meshes to obtain an initial human hip joint prosthesis stem; filling the sides of the initial human hip joint prosthesis stem, except for the pre-drilled holes on the sides and the femoral head fixation end, with a porous mesh structure of a preset thickness; and finally, 3D printing to obtain the solid hip joint prosthesis stem. The hip joint prosthesis stem and its manufacturing method provided by this invention can improve the stability of the prosthesis stem when installed on the human body.

[0009] However, while the orthopedic prostheses fabricated using the aforementioned 3D printing process allow for free design and control of the trabecular bone structure to promote bone fusion, they do not meet the fatigue performance requirements for some scenarios with extremely high fatigue performance demands, such as titanium alloy femoral stems subject to cyclic load fatigue. For instance, compared to traditional forging and casting processes, the 3D printing process for titanium alloys exhibits characteristics such as high residual stress, porosity defects, and poor tissue uniformity, resulting in poor fatigue performance and failing to meet the 5 million-cycle fatigue performance requirement for the hip joint femoral stem.

[0010] To improve fatigue resistance, a common heat treatment method is to heat-treat at temperatures above 740℃ (the α' phase decomposition temperature) to relieve stress and form a stable α+β phase structure, or α / α'+β phase structure, accompanied by microstructure coarsening. However, this method cannot eliminate porosity defects, resulting in a structure with low strength and high plasticity. Another commonly used heat treatment method is hot isostatic pressing at high temperature and pressure at the β phase transformation temperature. This method can effectively reduce porosity defects caused by forming, but because the temperature is usually above 900℃, the microstructure will be severely coarsened or even equiaxed, leading to a decrease in the fatigue performance of the component.

[0011] In addition, existing technologies have proposed other processing methods. For example, patent application CN115945697A discloses a damage-tolerant titanium alloy TC4 based on selective laser melting. The specific steps of the DT forming process are as follows: S1, TC4 is prepared by plasma rotating electrode method. DT titanium alloy powder; S2, Format conversion; S3, Slicing; S4, Process parameter setting; S5, Equipment preparation; S6, Printing test pieces; S7, Powder cleaning and sample removal; S8, Wire cutting; S9, Metallographic observation; S10, Component mechanical property test sample model; S11, Sample annealing; S12, Solution treatment and aging; S13, Elimination of internal porosity; S14, Mechanical testing; TC4 prepared by plasma rotating electrode method. Using DT titanium alloy powder as raw material, orthogonal experimental design was used to optimize process parameters to obtain high-density, low-defect deposited parts, followed by annealing. Solution aging Hot isostatic pressing (HIP) further regulates the internal structure and eliminates defects, resulting in a damage-tolerant titanium alloy with medium strength, high fracture toughness, and high fatigue strength.

[0012] However, the above method is aimed at the modified and high-cost titanium alloy TC4. DT materials are not suitable for low-cost, common titanium alloy TC4. Furthermore, the fundamental purpose is to maximize damage tolerance; using the aforementioned processing methods to fabricate TC4 components actually reduces their plasticity and fatigue strength. In other words, the performance of TC4 components prepared using these processes, especially their fatigue performance, still needs further improvement. Therefore, there is an urgent need for a 3D printing method that can improve the fatigue performance of TC4 orthopedic prostheses, particularly femoral stem prostheses. Summary of the Invention

[0013] The purpose of this invention is to provide a TC4 titanium alloy orthopedic prosthesis component, a femoral stem, and a heat treatment method thereof, which partially solves or alleviates the above-mentioned deficiencies in the prior art. This heat treatment method can improve the fatigue performance of the orthopedic prosthesis component, especially the cyclic load fatigue performance.

[0014] To solve the aforementioned technical problems, the present invention specifically adopts the following technical solution:

[0015] A first aspect of the present invention is to provide a heat treatment method for laser 3D printed TC4 titanium alloy orthopedic prosthesis components, comprising the steps of:

[0016] S101, the first component was obtained by manufacturing TC4 titanium alloy orthopedic prosthesis components using spot exposure laser 3D printing technology.

[0017] S102, the first component is placed in a vacuum heat treatment furnace for stress-relief annealing to obtain the second component; wherein the annealing temperature is lower than the α' phase decomposition temperature;

[0018] S103, the second component is heat-treated by hot isostatic pressing and then cooled to obtain a third component with an α / α'+β phase dual-state structure; wherein, the hot isostatic pressing temperature is 800℃-930℃, the pressure is controlled at 120MPa-200MPa, and the holding time is 2-4 hours.

[0019] S104 uses a high-temperature solid solution method to decompose the residual metastable α' phase, and then uses water quenching for rapid cooling after solid solution, with a cooling rate greater than 410℃ / s, thereby inhibiting the regeneration of the α' phase and forming the fourth component of a fine-grained basket-like α+β phase structure.

[0020] S105 employs an aging process to eliminate residual stress formed during the rapid cooling process of water quenching; the aging temperature is 500℃-550℃, and the aging time is 4-6 hours, resulting in the fifth component.

[0021] Preferably, the heat treatment method further includes the step of:

[0022] S106, the surface of the 3D printed TC4 titanium alloy orthopedic prosthesis component that has completed the above heat treatment process is ground and polished.

[0023] Preferably, the printing parameters in step S101 include: printing layer thickness T=30μm, laser power P=180W-200W, scanning spacing HS=100μm-130μm, scanning dot distance PD=50μm-80μm, and exposure time EP=40μs-100μs.

[0024] Preferably, the heat treatment regime in step S102 is: 450℃~550℃, held for 2-3 hours.

[0025] Preferably, the cooling step in step S103 specifically includes: first cooling the furnace to 450℃-550℃ at a cooling rate of 30℃ / min; and then placing it in the air for natural cooling after cooling to 450℃-550℃.

[0026] Preferably, the solution temperature in step S104 is 890℃-1050℃, and the solution time is 5-10 minutes.

[0027] Preferably, the first component has an α' martensitic structure and has porosity defects.

[0028] Preferably, before performing step S103, the procedure further includes the step of unloading the TC4 titanium alloy orthopedic prosthesis from the base plate.

[0029] A second aspect of the present invention is to provide a TC4 titanium alloy orthopedic prosthesis component, which is obtained by the above-mentioned heat treatment method and has a fine-grained basket-like α+β phase structure.

[0030] A third aspect of the present invention is to provide a TC4 titanium alloy femoral stem, which is obtained by the above-described heat treatment method and has a fine-grained basket-like α+β phase structure.

[0031] Beneficial Effects: This invention eliminates stress in laser-printed 3D components before directly subjecting them to hot isostatic pressing (HIP), ensuring virtually "no porosity defects." Solution treatment and aging then achieve a fine, uniform, high-strength, and fatigue-resistant microstructure. This invention innovatively combines stress-relief annealing, HIP, high-temperature solution quenching, and aging in a specific sequence. By precisely controlling the key parameters of each step, it avoids problems such as residual stress, porosity, metastable α' phase (martensite), and microstructure inhomogeneity inherent in traditional 3D-printed TC4 titanium alloy components. For example, the stress-relief annealing temperature is strictly controlled below the α' phase decomposition temperature to avoid early phase transformation interference. Furthermore, HIP is performed at the α+β phase temperature (800℃–930℃) to promote the formation of an α / α'+β biphase microstructure. High-temperature solution treatment followed by water quenching, with a cooling rate >410℃ / s, forces the decomposition of the residual α' phase and inhibits its regeneration, achieving the transformation from a metastable state to a stable, fine-grained basket-like α+β microstructure. This invention employs a series of "inhibition-decomposition-stabilization" controls on the α' phase. Compared to conventional heat treatment, which focuses solely on stress relief or densification, this invention adopts a "densification first, then strengthening" approach, balancing the two crucial indicators for medical implants: "near-zero defects" and "fine grains and high strength." Furthermore, the cooling rate requirement is greater than 410℃ / s, necessitating rapid water quenching to ensure that the α' phase does not precipitate after solution treatment, placing higher demands on equipment and process control.

[0032] Of course, the heat treatment method of the present invention is not limited to medical orthopedic implants, but can also be adapted to other application scenarios with very high requirements for fatigue resistance.

[0033] The orthopedic prosthetic components prepared using the method of the present invention have the following advantages:

[0034] High strength and hardness: to withstand the weight of the human body and active loads, and to reduce wear.

[0035] Excellent fatigue resistance: Human activity is a typical cyclic load, and the prosthesis must be able to withstand millions or even tens of millions of cycles.

[0036] Excellent corrosion resistance: It remains stable in the human body fluid environment for a long time and does not produce harmful ions. Fine-grained structures typically have a more uniform chemical composition and fewer grain boundary precipitates, resulting in better corrosion resistance.

[0037] Reliable internal quality: Any internal defects can become fatigue crack initiation points, leading to premature failure of the prosthesis. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. The elements or parts in the drawings are not necessarily drawn to scale. Obviously, the drawings described below are some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0039] Figure 1 This is a flowchart of an embodiment of a heat treatment method for laser 3D printed TC4 titanium alloy orthopedic prosthesis components according to the present invention;

[0040] Figure 2 To reflect Figure 1 A schematic diagram of the heating curve for the intermediate heat treatment method;

[0041] Figure 3A for Figure 1 A comparison diagram of the melt channels formed under different printing parameters in step S101: parameter 1, parameter 2, and parameter 3.

[0042] Figure 3B for Figure 1 A comparison diagram of the molten pool formed under different printing parameters in step S101: parameter 1, parameter 2, and parameter 3.

[0043] Figure 4A for Figure 1 A schematic diagram of the metallographic structure of the second component obtained in step S102 of the heat treatment method shown;

[0044] Figure 4B for Figure 1 A schematic diagram of the metallographic structure of the third component obtained in step S103 of the heat treatment method shown.

[0045] Figure 4C for Figure 1 A schematic diagram of the metallographic structure of the fourth component obtained in step S104 of the heat treatment method shown.

[0046] Figure 5A and Figure 5B All Figure 1 The residual stress distribution diagram of the first component obtained in step S101 of the heat treatment method shown in the figure before stress relief annealing.

[0047] Figure 5C for Figure 1 The residual stress diagram of the first component before stress-relief annealing obtained in step S101 of the heat treatment method shown.

[0048] Figure 5D and Figure 5E All Figure 1 The residual stress distribution diagram of the first component after stress-relief annealing, obtained in step S101 of the heat treatment method shown;

[0049] Figure 5F for Figure 1 The residual stress diagram of the first component after stress-relief annealing obtained in step S101 of the heat treatment method shown. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0051] Example 1:

[0052] See Figure 1 The heat treatment method for laser 3D printed TC4 titanium alloy orthopedic prosthesis components of the present invention specifically includes the following steps:

[0053] S101, the first component was obtained by manufacturing TC4 titanium alloy orthopedic prosthesis components using spot exposure laser 3D printing technology.

[0054] In some embodiments, the printing parameters of step S101 include: printing layer thickness T=30μm, laser power P=180W-200W, scanning spacing HS=100μm-130μm, scanning dot distance PD=50μm-80μm, and exposure time EP=40μs-130μs (preferably, EP=40μs-100μs, more preferably, EP=90μs-100μs).

[0055] Based on the above printing parameters (see...) Figure 3A and Figure 3B Parameter 2: Laser power 180W-200W, exposure time 90μs-130μs, scanning point spacing 50μm-70μm, scanning interval 100μm-130μm). The first component obtained in step S101 has an α' martensite structure and contains printing porosity defects, but the forming defects are less than 100μm. See [link to relevant documentation]. Figure 3A and Figure 3B ;

[0056] And based on Figure 3A and Figure 3BThe forming defects of the first component prepared by parameter 1 (laser power 130W, exposure time 50μs, scanning point spacing 90μm) or parameter 3 (laser power 300W, exposure time 150μs, scanning point spacing 50μm) are all greater than 100μm.

[0057] S102, the first component is placed in a vacuum heat treatment furnace for stress-relief annealing to obtain the second component.

[0058] In some embodiments, the annealing temperature is lower than the α' phase decomposition temperature.

[0059] See Figure 2 In some embodiments, the heat treatment temperature in step S102 is 450℃-550℃, held for 2-3 hours, and then placed in a furnace for natural cooling.

[0060] Specifically, the first component printed in step S101, together with the printing base plate, is subjected to heat treatment using a vacuum heat treatment furnace for stress-relief annealing. Through step S102, residual stress from forming is essentially eliminated without altering the original microstructure and phase composition.

[0061] Further, after stress-relief annealing, the TC4 titanium alloy orthopedic prosthesis, such as the femoral stem, is removed from the base plate using wire cutting to obtain the second component. For details, see [link to documentation]. Figure 3A and Figure 3B , Figure 4A Since the original microstructure and phase conditions were not changed, the second component is still α' martensite. Although it contains printing pore-type defects, the forming defects are less than 100μm.

[0062] See Figures 5A-5C Before stress-relief annealing, the residual stress Sigma(x) of the first component was 451 MPa (i.e., the residual stress along the X-axis was 451 MPa); see [link / reference]. Figures 5D-5F After stress-relief annealing, the residual stress Sigma(x) of the second component is 66MPa (i.e., the residual stress along the X-axis is 66MPa), which means that the residual stress of the component is significantly reduced after stress-relief annealing.

[0063] S103 is heat-treated by hot isostatic pressing and then cooled to obtain the third component.

[0064] See Figure 2 In some embodiments, the hot isostatic pressing temperature is 800℃-930℃, the pressure is controlled at 120MPa-200MPa, and the holding time is 2-4 hours.

[0065] In some embodiments, the cooling step in step S103 specifically includes: first cooling the furnace to 450°C-550°C at a cooling rate of 30°C / min; and then placing it in the air for natural cooling after cooling to 450°C-550°C.

[0066] This step, through high temperature and high pressure, can basically eliminate the forming pore-type defects in steps S101 and S102 above (for example, through high temperature and high pressure, the residual pores and unfused defects inside the component are pressed together and healed under the action of creep and diffusion), that is, to densify the component, and then through rapid cooling, significant coarsening or equiaxing of the structure can be suppressed.

[0067] See Figure 4B After heat treatment by hot isostatic pressing and cooling, the third component exhibits a dual-phase structure of α / α'+β phases, with coarse structure and elimination of defects.

[0068] S104 was decomposed by high-temperature solid solution treatment to remove the residual metastable α' phase. After solid solution treatment, it was rapidly cooled by water quenching at a rate greater than 410℃ / s, thereby inhibiting the regeneration of the α' phase and forming a fine-grained basket-like α+β phase structure, thus obtaining the fourth component.

[0069] See Figure 2 In some embodiments, the solution temperature in step S104 is 890℃-1050℃, and the solution time is 5-10 minutes.

[0070] See Figure 4C After decomposing the residual metastable α' phase and rapidly cooling, the fourth component exhibits a basket-like structure of α+β phase, with refined grains and eliminated defects.

[0071] This step adjusts the content and size of the α phase by controlling the solution temperature and solution time, and then rapidly cooling to fix the high-temperature β phase into a metastable α' or supercooled β phase, that is, transforming the coarse lamellar structure into a finer biphase structure, which is beneficial to balancing strength, plasticity and fatigue performance.

[0072] S105, using an aging process, eliminates the residual stress formed during the rapid cooling process of water quenching, resulting in the fifth component, namely the orthopedic prosthesis component.

[0073] See Figure 2 In some embodiments, the aging temperature in step S105 is 500℃-550℃, the aging time is 4-6 hours, and then furnace cooling is performed.

[0074] Furthermore, in some other embodiments, the method further includes the step: S106, performing surface grinding and polishing on the TC4 titanium alloy orthopedic prosthesis component that has undergone the above heat treatment process.

[0075] This step uses an aging process to decompose the α' or supercooled β phase formed after solution quenching, precipitating fine secondary α phases, thereby improving the material strength.

[0076] Although solution treatment and aging can strengthen and optimize the microstructure, improper parameters can lead to microstructure coarsening or excessive lamellarity, thus affecting fatigue resistance. Similarly, improper parameter control in hot isostatic pressing and stress-relief annealing can also affect fatigue resistance. Therefore, this embodiment addresses this by strictly controlling the temperature curves of each step, such as... Figure 2 As shown, this improves the overall fatigue resistance of the components.

[0077] This embodiment eliminates stress in the component through low-temperature annealing, densifies the component through hot isostatic pressing, and then uses solution treatment and aging treatment to regulate the microstructure and strengthen the component, thereby comprehensively improving the mechanical properties of the TC4 component, significantly enhancing its fatigue resistance, and thus improving the fatigue limit of the component.

[0078] Accordingly, the present invention also provides an orthopedic prosthesis component obtained based on the above heat treatment method, which has a fine-grained basket-like α+β phase structure.

[0079] Example 2:

[0080] See Figure 1 The heat treatment method for laser 3D printed TC4 titanium alloy femoral stem of the present invention specifically includes the following steps:

[0081] S101, the first component was obtained by manufacturing the TC4 titanium alloy femoral stem using a spot exposure laser 3D printing process.

[0082] In some embodiments, the printing parameters of step S101 include: printing layer thickness T=30μm, laser power P=180W-200W, scanning spacing HS100μm-130μm, scanning dot distance PD=50μm-80μm, and exposure time EP=40μs-100μs.

[0083] Based on the above printing parameters (see...) Figure 3A and Figure 3B (Parameter 2), the first component obtained in step S101 has an α' martensitic structure and contains printing porosity defects, but the forming defects are less than 100 μm. See [reference needed]. Figure 3A and Figure 3B Based on Figure 3A and Figure 3B The forming defects of the first component prepared with parameter 1 or parameter 3 are all greater than 100 μm.

[0084] S102, the first component is placed in a vacuum heat treatment furnace for stress-relief annealing to obtain the second component.

[0085] In some embodiments, the annealing temperature is lower than the α' phase decomposition temperature.

[0086] In some embodiments, the heat treatment regime in step S102 is: 450℃~550℃, held for 2-3 hours, and then placed in a furnace for natural cooling.

[0087] Specifically, the first component printed in step S101, together with the printing base plate, is subjected to heat treatment using a vacuum heat treatment furnace for stress-relief annealing. Through step S102, residual stress from forming is essentially eliminated without altering the original microstructure and phase composition.

[0088] Furthermore, after stress-relief annealing, the femoral stem is removed from the base plate using wire cutting to obtain the second component. See details... Figure 3A and Figure 3B Since the original microstructure and phase conditions were not changed, the second component is still α' martensite. Although it contains printing pore-type defects, the forming defects are less than 100μm.

[0089] S103 is heat-treated by hot isostatic pressing and then cooled to obtain the third component.

[0090] In some embodiments, the hot isostatic pressing temperature is 800℃-930℃, the pressure is controlled at 120MPa-200MPa, and the holding time is 2-4 hours.

[0091] In some embodiments, the cooling step in step S103 specifically includes: first cooling the furnace to 450~550°C at a cooling rate of 30°C / min; and then placing it in the air for natural cooling after cooling to 450~550°C.

[0092] This step, through high temperature and high pressure, can basically eliminate the forming pore-type defects in steps S101 and S102 above, and through rapid cooling, it can suppress the bending deformation of the α phase grain boundaries during the transformation from α' phase to α / α'+β phase, and control the coarsening or equiaxing of the microstructure.

[0093] S104 uses a high-temperature solution method to decompose the residual metastable α' phase, and then uses water quenching for rapid cooling at a rate greater than 410℃ / s to suppress the regeneration of the α' phase, thereby forming a fine-grained basket-like α+β phase structure to obtain the fourth component.

[0094] In some embodiments, the solution temperature in step S104 is 890℃-1050℃, and the solution time is 5-10 minutes.

[0095] S105 employs an aging process to eliminate residual stress formed during the rapid cooling process of water quenching.

[0096] In some embodiments, the aging temperature in step S105 is 500~550℃ and the aging time is 4-6 hours, to obtain the fifth component, namely the TC4 titanium alloy femoral stem.

[0097] S106, the surface of the 3D-printed TC4 titanium alloy femoral stem that has completed the above heat treatment process is ground and polished.

[0098] Accordingly, the present invention also provides a TC4 titanium alloy femoral stem obtained based on the above heat treatment method, which has a fine-grained basket-like α+β phase structure.

[0099] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0100] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A heat treatment method for laser 3D printing of a TC4 titanium alloy orthopaedic prosthesis component, characterized in that, Including the following steps: S101, the first component was obtained by manufacturing TC4 titanium alloy orthopedic prosthesis components using spot exposure laser 3D printing technology. S102, the first component is placed in a vacuum heat treatment furnace for stress-relief annealing to obtain the second component; wherein, the annealing temperature is lower than the α' phase decomposition temperature; specifically, the heat treatment temperature is 450℃-550℃, held for 2-3 hours, and then placed in the furnace for natural cooling; S103, the second component is heat-treated by hot isostatic pressing. It is first cooled in the furnace to 450℃-550℃ at a cooling rate of 30℃ / min; and after cooling to 450℃-550℃, it is placed in air for natural cooling; to obtain the third component with an α / α'+β phase bimodal structure; wherein, the hot isostatic pressing temperature is 800℃-930℃, the pressure is controlled at 120MPa-200MPa, and the holding time is 2-4 hours; S104 uses a high-temperature solution method to decompose the residual metastable α' phase, and then uses water quenching for rapid cooling after solution to inhibit the regeneration of the α' phase, forming the fourth component of a fine-grained basket-like α+β phase structure; the solution temperature is 890℃-1050℃, and the solution time is 5-10 minutes. S105 employs an aging process to eliminate residual stress formed during rapid water quenching; the aging temperature is 500℃-550℃, and the aging time is 4-6 hours, resulting in a fifth component with a fine-grained basket-like α+β phase structure.

2. The heat treatment method of laser 3D printing TC4 titanium alloy orthopaedic prosthesis components according to claim 1, characterized in that, It also includes the following steps: S106, the surface of the 3D printed TC4 titanium alloy orthopedic prosthesis component that has completed the above heat treatment process is ground and polished.

3. The heat treatment method of laser 3D printing TC4 titanium alloy orthopaedic prosthesis components according to claim 1, characterized in that, The printing parameters for step S101 include: printing layer thickness T=30μm, laser power P=180W-200W, scanning spacing HS=100μm-130μm, scanning dot distance PD=50μm-80μm, and exposure time EP=40μs-100μs.

4. A heat treatment method for a laser 3D printed TC4 titanium alloy orthopedic prosthesis component according to any one of claims 1 to 3, characterized in that, The first component has an α' martensitic structure and exhibits porosity defects.

5. A heat treatment method for a laser 3D printed TC4 titanium alloy orthopedic prosthesis component according to any one of claims 1 to 3, characterized in that, Before performing step S103, the following steps are also included: Remove the TC4 titanium alloy orthopedic prosthesis from the base plate.

6. A TC4 titanium alloy orthopaedic prosthesis component, characterized in that, It is obtained by any of the heat treatment methods described in claims 1 to 4, and has a fine-grained basket-like α+β phase structure.

7. A TC4 titanium alloy femoral stem, characterized in that, It is obtained by any of the heat treatment methods described in claims 1 to 4, and has a fine-grained basket-like α+β phase structure.

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