High-strength pure titanium rod wire material and preparation method thereof

Abstract

The invention provides a high-strength pure titanium rod wire and a preparation method thereof, and relates to the technical field of biomedical metal materials, and the preparation method comprises the following steps: preparing materials according to industrial pure titanium components, carrying out vacuum consumable smelting to obtain a titanium ingot blank, and carrying out cogging forging and continuous rolling on the titanium ingot blank to obtain a coiled rod blank; the coiled bar blank is subjected to hot drawing to obtain a pure titanium bar, and the pure titanium bar subjected to hot drawing is sequentially subjected to scaling treatment, heat treatment, cold drawing, sliding block straightening, stress relief annealing and centerless grinding to obtain a finished product of the high-strength pure titanium bar wire. According to the method, the surface reduction rate is controlled through cold drawing, the performance of the rod wire is adjusted through a reasonable heat treatment system, metastable structures in the alloy are obviously deformed and close to each other through cold drawing, the deformation amount of cold drawing is continuously increased, grain boundaries and dendritic grain boundaries are close to each other, the interface distance is gradually reduced, grains and the metastable structures are refined, and the yield of the rod wire is increased. Due to the increase of dislocation density and grain refinement, the yield strength and tensile strength of the cold-drawn pure titanium rod wire are improved.

Description

Technical Field

[0001] The present application relates to the technical field of biomedical metal materials, and more specifically, to a high-strength pure titanium rod and wire material and a preparation method thereof. Background Art

[0002] With the development of medical metal materials, titanium and titanium-based alloys have been extremely active in the field of implant materials due to their outstanding advantages of biocompatibility, corrosion resistance, chemical stability, and non-cytotoxicity. In order to further improve the scope of application of pure titanium implant materials, so that they can be implanted alone or used in combination with materials such as polyetheretherketone and carbon fiber, it is very necessary to improve their strength. Poor control of the uniformity, consistency and stability of pure titanium components will cause unstable mechanical properties of rods and wires. In the prior art, the process solutions for preparing pure titanium rods and wires are:

[0003] The Chinese invention patent with publication number CN117960830A is a method for preparing high-performance medical TA3G pure titanium wire, which solves the technical problem that the mechanical properties of existing TA3G pure titanium wire cannot meet the use requirements, comprising the following steps: (1) selecting and uniformly mixing grade 1 or above sponge titanium, Fe and TiO2 to form an electrode, and performing vacuum consumable smelting for more than two times to obtain a TA3G titanium ingot that complies with GB / T3620.1-2016; (2) forging to obtain a rod blank; (3) Hot rolling to obtain rods; (4) round drawing treatment at room temperature, drawing speed ≤5.0 m / min to obtain rods; (5) peeling treatment, requiring the peeling speed to be less than 3.0 m / min; (6) roller die drawing, roller die drawing speed ≤5.0 m / min, and deformation controlled to be above 65%; (7) slider straightening; (8) stress relief annealing treatment, heat treatment temperature is 600-800°C, keep warm for a period of time, and air cool; (9) centerless grinding, finally preparing medical high-performance TA3G pure titanium wire.

[0004] In order to further improve the mechanical properties of pure titanium implant materials and further expand the scope of application of pure titanium implant materials, a method for preparing high-strength pure titanium rods and wires is needed. Summary of the invention

[0005] In order to solve the above problems, the technical solution adopted in this application is a high-strength pure titanium rod wire and a preparation method thereof, comprising the following steps:

[0006] According to the industrial pure titanium component, vacuum consumable smelting is adopted to obtain titanium ingot blanks, the titanium ingot blanks are subjected to blanking forging and continuous rolling to obtain coiled bar blanks, the coiled bar blanks are subjected to hot drawing to obtain pure titanium bars, and the pure titanium bars after hot drawing are sequentially subjected to peeling treatment, heat treatment, cold drawing, slider straightening, stress relief annealing and centerless grinding to obtain high-strength pure titanium rod and wire products.

[0007] Optionally, the raw materials for batching include sponge titanium, reduced iron powder and titanium dioxide of grade one or above, and vacuum consumable smelting is performed more than twice.

[0008] Optionally, the temperature of the blank forging is 1000℃~1100℃, and continuous rolling is carried out after forging. The temperature of the continuous rolling is 750℃~850℃, the rolling speed is 1m / s~5m / s, the deformation in each pass of the continuous rolling is 50%~75%, and the cumulative deformation is more than 99.50%.

[0009] Optionally, the temperature of the hot drawing is 700° C. to 750° C., the drawing speed is ≤3.0 m / min, and graphite powder is used as a lubricant to adhere to the surface of the coiled rod blank during the hot drawing process to reduce friction loss.

[0010] Optionally, the peeling process includes peeling the pure titanium rod after hot drawing using a centerless lathe to remove surface defects of the rod to obtain a bright and defect-free rod.

[0011] Optionally, the heat treatment temperature is 650° C. to 700° C., the heat preservation time is 1 to 3 hours, and after the heat treatment, the material is cooled to room temperature in air.

[0012] Optionally, the drawing speed of cold drawing is 2m / min to 5m / min, the diameter reduction of each cold drawing pass is 0.3mm to 0.5mm, and the total deformation of cold drawing is 40% to 60%.

[0013] Optionally, the slider straightening includes using a vertical straightening machine with upper and lower rollers to cold-process the rod in a continuous straightening manner with upper and lower rollers rotating and rolling forward. After straightening, the rod is not allowed to have wavy cold bends or hyperbolic cold bends that cannot be straightened. The straightness is ≤0.10mm / m and the surface scratch depth is ≤0.07mm.

[0014] Optionally, the stress relief annealing includes performing stress relief heat treatment on the pure titanium rod after the slider is straightened, the heat treatment temperature of the stress relief annealing is 450°C to 550°C, the holding time is 1 to 3 hours, and after the stress relief heat treatment, the stress relief annealing process is completed by cooling to room temperature in air.

[0015] The present application also provides a high-strength pure titanium rod and wire material, which is prepared by implementing any of the above-mentioned methods for preparing high-strength pure titanium rod and wire material.

[0016] The beneficial effects of a high-strength pure titanium rod and wire material and a preparation method thereof provided in this application are:

[0017] 1. The present invention uses cold drawing to control the area reduction rate and a reasonable heat treatment system to adjust the performance of the rod and wire. Cold drawing causes the metastable structure in the alloy to deform significantly and move closer to each other. As the cold drawing deformation increases, the grain boundary and the dendrite boundary move closer to each other, and the interface distance gradually decreases, thereby refining the grains and metastable structure. Due to the increase in dislocation density and grain refinement, the yield strength and tensile strength of the pure titanium rod and wire after cold drawing are improved. As the deformation increases, the internal grains of pure titanium continue to slip. As the slip system decreases and the lattice produces dislocation distortion, further deformation is prevented, so the plastic deformation resistance is increased, the cold work hardening phenomenon of pure titanium is aggravated, and finally the tensile strength of pure titanium is increased.

[0018] 2. The present invention adopts the slider straightening method for cold straightening, which eliminates the influence of high temperature of electric straightening on the performance of the rod and obtains a balanced residual stress state. The rod prepared by this method has good tensile strength and improves the consistency and stability of the product performance after heat treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art.

[0020] Figure 1 This is the metallographic structure diagram of the finished pure titanium rod in Example 1 of the present application;

[0021] Figure 2 This is the metallographic structure diagram of the finished pure titanium rod in Example 2 of the present application;

[0022] Figure 3 This is the metallographic structure diagram of the finished pure titanium rod in Example 3 of the present application;

[0023] Figure 4 This is the metallographic structure diagram of the finished pure titanium rod in Example 4 of the present application;

[0024] Figure 5 This is the metallographic structure diagram of the finished pure titanium rod in Example 5 of the present application;

[0025] Figure 6 This is the metallographic structure diagram of the finished pure titanium rod in Example 6 of the present application. DETAILED DESCRIPTION

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0027] Example 1

[0028] The high-strength pure titanium rod and wire provided in this embodiment includes the following components and the weight percentage of each component: 0.41% Fe element, 0.34% O element, 0.0072% C element, 0.0008% H element, 0.0045% N element, and the balance is Ti. It meets the chemical composition requirements of TA4G industrial pure titanium in GB / T3620.1-2016 standard.

[0029] This embodiment includes the following steps:

[0030] S1: Use first-grade and above titanium sponge, reduced iron powder, and titanium dioxide, mix materials according to the composition of industrial pure titanium, and use three vacuum consumable smelting to obtain TA4G titanium ingot blanks with stable and uniform composition and in line with GB / T3620.1-2016 standards. The titanium sponge grade standard complies with GB / T2524-2002 regulations;

[0031] S2: The Φ600.0mm titanium ingot is forged at 1000°C, and then continuously rolled at 750°C at a rolling speed of 1m / s. The deformation amount of each pass in the continuous rolling is 50%, and the cumulative deformation amount is more than 99.5%. After rolling, a coil bar with a size of Φ13.0mm is obtained.

[0032] S3: The Φ13.0 coiled bar blank is subjected to two passes of hot drawing to obtain a Φ11.80 pure titanium bar. A drawing machine is used for hot drawing. The drawing temperature is 700°C and the drawing speed is ≤3.0m / min. Graphite powder is used as a lubricant to adhere to the surface of the bar to reduce friction loss.

[0033] S4: The bar is peeled after drawing; a centerless lathe is used for peeling to obtain a Φ11.40 pure titanium bar. The peeling speed is required to be 2.0m / min. After peeling 0.40mm, there should be no serious peeling marks and bite marks on the surface.

[0034] S5: heat treatment is performed on the peeled rod: the heat treatment temperature is 650°C, the heat treatment holding time is 1 hour, and after the heat treatment, the rod is cooled to room temperature in air.

[0035] S6: Cold drawing: After the defect-free rod is coated, it is subjected to multiple passes of cold drawing using a drawing machine. The drawing speed of the cold drawing is 2m / min, and the diameter reduction of each cold drawing pass is 0.3mm. The total cold drawing deformation is 40%, and the semi-finished pure titanium rod is processed.

[0036] S7: Slider straightening includes the use of a vertical straightening machine with two upper and lower rollers to cold-process the bar by a continuous straightening method of rotating and rolling forward with two upper and lower rollers. After straightening, the bar is not allowed to have wavy cold bends or hyperbolic cold bends that cannot be straightened. The straightness is ≤0.10mm / m and the surface scratch depth is ≤0.07mm.

[0037] S8: Stress relief annealing: The pure titanium rod after the slider is straightened is subjected to stress relief heat treatment; the heat treatment temperature of the stress relief annealing is 450°C, the holding time is 1h, and after the stress relief heat treatment, the rod is cooled to room temperature in air to complete the stress relief annealing process, and the rod after stress relief annealing is obtained.

[0038] S9: Centerless grinding: The rods after stress relief heat treatment are subjected to centerless grinding to finally produce high-strength pure titanium rod and wire products.

[0039] Example 2

[0040] The TA4G high-strength pure titanium rod provided in this embodiment includes the following components and the weight percentage of each component: 0.39% Fe element, 0.35% O element, 0.0081% C element, 0.0009% H element, 0.005% N element, and the balance is Ti. It meets the chemical composition requirements of industrial TA4G industrial pure titanium in GB / T3620.1-2016 standard.

[0041] The difference from Example 1 is that in this embodiment, the blanking forging temperature is 1025°C, and after forging, continuous rolling is performed at 775°C, and the rolling speed is 2m / s. The deformation amount in each pass of continuous rolling is 55%. A single pass hot drawing is performed on the Φ13.0 coil bar billet to obtain a Φ12.20 pure titanium bar, and a drawing machine is selected for hot drawing treatment, the drawing temperature is 710°C, and the drawing speed is ≤3.0m / min.

[0042] The peeled bars are heat treated: the heat treatment temperature is 675°C, the heat treatment holding time is 2h, the cold drawing speed is 3m / min, and the diameter reduction of each cold drawing is 0.4mm, the total cold drawing deformation is 45%, the heat treatment temperature of stress relief annealing is 475°C, and the holding time is 2h.

[0043] Example 3

[0044] The TA4G high-strength pure titanium rod provided in this embodiment includes the following components and the weight percentage of each component: 0.40% Fe element, 0.36% O element, 0.0091% C element, 0.0006% H element, 0.0035% N element, and the balance is Ti. It meets the chemical composition requirements of industrial TA4G pure titanium in GB / T3620.1-2016 standard.

[0045] The difference from Example 1 is that in this embodiment, the blanking forging temperature is 1050°C, and after forging, continuous rolling is performed at 800°C, and the rolling speed is 3m / s. The deformation amount in each pass of continuous rolling is 60%. A single pass hot drawing is performed on the Φ13.0 coil bar blank to obtain a Φ12.20 pure titanium bar, and a drawing machine is selected for hot drawing treatment, the drawing temperature is 720°C, and the drawing speed is ≤3.0m / min.

[0046] The peeled bars are heat treated: the heat treatment temperature is 700°C, the heat treatment holding time is 3h, the cold drawing speed is 4m / min, and the diameter reduction of each cold drawing is 0.5mm, the total cold drawing deformation is 50%, the stress relief annealing heat treatment temperature is 500°C, and the holding time is 3h.

[0047] Example 4

[0048] The TA4G high-strength pure titanium rod provided in this embodiment includes the following components and the weight percentage of each component: 0.40% Fe element, 0.33% O element, 0.0075% C element, 0.0007% H element, 0.0041% N element, and the balance is Ti. It meets the chemical composition requirements of industrial TA4G pure titanium in GB / T3620.1-2016 standard.

[0049] The difference from Example 1 is that in this embodiment, the blanking forging temperature is 1075°C, and after forging, continuous rolling is performed at 825°C, and the rolling speed is 4m / s. The deformation amount in each pass of continuous rolling is 65%. A single pass hot drawing is performed on the Φ13.0 coil bar blank to obtain a Φ12.20 pure titanium bar, and a drawing machine is selected for hot drawing treatment, the drawing temperature is 730°C, and the drawing speed is ≤3.0m / min.

[0050] The peeled bars are heat treated: the heat treatment temperature is 650°C, the heat treatment holding time is 1h, the cold drawing speed is 5m / min, and the diameter reduction of each cold drawing is 0.3mm, the total cold drawing deformation is 55%, the heat treatment temperature of stress relief annealing is 525°C, and the holding time is 1h.

[0051] Example 5

[0052] The TA4G high-strength pure titanium rod provided in this embodiment includes the following components and the weight percentage of each component: 0.42% Fe element, 0.34% O element, 0.01% C element, 0.0008% H element, 0.0033% N element, and the balance is Ti. It meets the chemical composition requirements of industrial TA4G pure titanium in GB / T3620.1-2016 standard.

[0053] The difference from Example 1 is that in this embodiment, the blanking forging temperature is 1100°C, and after forging, continuous rolling is performed at 850°C, and the rolling speed is 5m / s. The deformation amount in each pass of continuous rolling is 70%. A single pass hot drawing is performed on the Φ13.0 coil bar blank to obtain a Φ12.20 pure titanium bar, and a drawing machine is selected for hot drawing treatment, the drawing temperature is 740°C, and the drawing speed is ≤3.0m / min.

[0054] The peeled bars are heat treated: the heat treatment temperature is 650°C, the heat treatment holding time is 1h, the cold drawing speed is 2m / min, and the diameter reduction of each cold drawing is 0.3mm, the total cold drawing deformation is 60%, the heat treatment temperature of stress relief annealing is 550°C, and the holding time is 1h.

[0055] Example 6

[0056] The TA4G high-strength pure titanium rod provided in this embodiment includes the following components and the weight percentage of each component: 0.42% Fe element, 0.37% O element, 0.0089% C element, 0.0006% H element, 0.0036% N element, and the balance is Ti. It meets the chemical composition requirements of TA4G industrial pure titanium in GB / T3620.1-2016 standard.

[0057] The difference from Example 1 is that in this embodiment, the blanking forging temperature is 1000°C, and after forging, continuous rolling is performed at 850°C, and the rolling speed is 1m / s. The deformation amount of each pass in the continuous rolling is 70%. A single pass hot drawing is performed on the Φ13.0 coil bar blank to obtain a Φ12.20 pure titanium bar, and a drawing machine is selected for hot drawing treatment, the drawing temperature is 740°C, and the drawing speed is ≤3.0m / min.

[0058] The peeled bars are heat treated: the heat treatment temperature is 650°C, the heat treatment holding time is 1h, the cold drawing speed is 2m / min, and the diameter reduction of each cold drawing is 0.3mm, the total cold drawing deformation is 40%, and the heat treatment temperature of stress relief annealing is 550°C, and the holding time is 1h.

[0059] Table 1 Mechanical properties test statistics of Example 1 to Example 6

[0060]

[0061] It can be seen from Table 1 that the room temperature tensile strength is greater than 580 MPa, the yield strength is greater than 485 MPa, and the elongation is greater than 15%, which fully meets and exceeds the requirements of GB / T13810-2017 standard.

[0062] from Figure 1-Figure 6 It can be seen that the high-strength pure titanium rod and wire prepared by the high-strength pure titanium rod and wire preparation method provided in this application has a grain size of 1.6-3.2μm and a uniform and fine microstructure. It can be seen from the figure that it fully meets and exceeds the organizational requirements of the GB / T13810-2017 standard.

[0063] The results of the embodiment show that the present invention adjusts the performance of the rod and wire by controlling the area reduction rate by cold drawing and a reasonable heat treatment system. The method uses room temperature drawing and rounding to improve the uniformity of the structure and the strength. The slider straightening and stress relief annealing are used to eliminate the tensile stress and compressive stress in the rod and wire, making it close to a stress-free state. This is because: during the cold drawing process, the grains of the metal material will become longer along the drawing direction and flatten along the vertical drawing direction. This deformation helps to improve the uniformity of the material's structure. Cold drawing can cause plastic deformation of the material, which can refine the grains and increase the density of the grain boundaries, thereby improving the strength of the material. According to the Hall-Petch formula, the reduction of grain size will increase the yield strength of the material. By means of slider straightening and stress relief annealing, the tensile stress and compressive stress in the wire are eliminated, the internal stress of the material is reduced, thereby improving the dimensional stability of the material and reducing deformation during processing. The material after cold drawing is properly heat treated to restore part of the plasticity while maintaining a high strength, thereby improving the overall mechanical properties of the material. Cold drawing causes the metastable structure in the alloy to deform significantly and move closer to each other. As the amount of cold drawing deformation increases, the grain boundaries and dendrite boundaries move closer to each other, and the interface distance gradually decreases, thereby refining the grains and metastable structure. Due to the increase in dislocation density and grain refinement, the yield strength and tensile strength of the pure titanium rod and wire after cold drawing are improved, and while meeting the standard requirements, the strength is further improved, thereby expanding the scope of application of the high-strength pure titanium rod and wire provided in this application.

[0064] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for preparing high-strength pure titanium rod and wire, characterized in that: The following steps are involved: According to the industrial pure titanium component, vacuum consumable smelting is adopted to obtain titanium ingot blanks, the titanium ingot blanks are subjected to blanking forging and continuous rolling to obtain coiled bar blanks, the coiled bar blanks are subjected to hot drawing to obtain pure titanium bars, and the hot-drawn pure titanium bars are sequentially subjected to peeling treatment, heat treatment, cold drawing, slider straightening, stress relief annealing and centerless grinding to obtain high-strength pure titanium rod and wire finished products.

2. The method for preparing high-strength pure titanium rod and wire according to claim 1, characterized in that: The raw materials for batching include sponge titanium of grade one or above, reduced iron powder and titanium dioxide, and the vacuum consumable smelting is performed more than twice.

3. The method for preparing high-strength pure titanium rod and wire according to claim 2, characterized in that: The temperature of the blank forging is 1000°C to 1100°C, and continuous rolling is performed after forging. The temperature of the continuous rolling is 750°C to 850°C, the rolling speed is 1m / s to 5m / s, the deformation amount of each pass in the continuous rolling is 50% to 75%, and the cumulative deformation amount is more than 99.50%.

4. The method for preparing high-strength pure titanium rod and wire according to claim 2, characterized in that: The temperature of the hot drawing is 700° C. to 750° C., and the drawing speed is ≤3.0 m / min. During the hot drawing process, graphite powder is used as a lubricant to adhere to the surface of the coiled rod blank to reduce friction loss.

5. The method for preparing high-strength pure titanium rod and wire according to claim 2, characterized in that: The peeling treatment includes peeling the pure titanium rod after hot drawing using a centerless lathe to remove surface defects of the rod to obtain a bright and defect-free rod.

6. The method for preparing high-strength pure titanium rod and wire according to claim 1, characterized in that: The heat treatment temperature is 650° C. to 700° C., the heat preservation time is 1 to 3 hours, and after the heat treatment, the mixture is cooled in air to room temperature.

7. The method for preparing high-strength pure titanium rod and wire according to claim 2, characterized in that: The drawing speed of the cold drawing is 2m / min-5m / min, the diameter reduction of each cold drawing pass is 0.3mm-0.5mm, and the total deformation of the cold drawing is 40%-60%.

8. The method for preparing high-strength pure titanium rod and wire according to claim 7, characterized in that: The slider straightening includes using an upper and lower roller vertical straightening machine to cold process the rod in a continuous straightening manner with upper and lower rollers rotating and rolling forward. After straightening, the rod is not allowed to have wavy cold bends or hyperbolic cold bends that cannot be straightened. The straightness is ≤0.10mm / m and the surface scratch depth is ≤0.07mm.

9. The method for preparing high-strength pure titanium rod and wire according to claim 2, characterized in that: The stress relief annealing includes performing stress relief heat treatment on the pure titanium rod after the slider is straightened. The heat treatment temperature of the stress relief annealing is 450°C to 550°C, the insulation time is 1 to 3 hours, and after the stress relief heat treatment, the rod is cooled in air to room temperature to complete the stress relief annealing process.

10. A high-strength pure titanium rod and wire, characterized in that: The high-strength pure titanium rod and wire is prepared by implementing the method for preparing the high-strength pure titanium rod and wire according to any one of claims 1 to 9.

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