Modified titanium alloy for improving cutting performance, profile, and preparation method therefor

Abstract

The present disclosure provides a modified titanium alloy for improving cutting performance, a profile, and a preparation method therefor. The modified titanium alloy for improving cutting performance comprises the following components in percentage by mass: 0.3-3% of Al, 0.4-3.0% of Zr, 0.05-0.3% of Si, 0.25-0.5% of Fe, 0.25-0.4% of O, and the balance being Ti. In the present disclosure, the elements Si, Zr, and Al are added on the basis of a standard TA4 titanium alloy. Since Al and Si easily precipitate at grain boundaries and Si and Zr act to hinder dislocation movement, the rigidity of a workpiece material during computer numerical control machining is improved, elastic deformation and vibration during workpiece machining are suppressed, and the occurrence of a built-up edge phenomenon is reduced; in addition, excellent chip-breaking properties enable a large amount of chips to be carried away along with a cutting coolant, thereby mitigating hardness reduction and wear caused by material adhesion and heat buildup on a tool tip, and improving tool life and workpiece machining quality.

Description

A modified titanium alloy with improved machinability, a profile, and a method for preparing the same.

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Chinese Patent Application No. 2024109380141, filed on July 12, 2024, entitled "A modified titanium alloy with improved machinability, a profile and a method for preparing the same", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure pertains to the field of metallic materials, specifically relating to a modified titanium alloy with improved machinability, a profile, and a method for preparing the same. Background Technology

[0004] TA4 titanium alloy possesses excellent mechanical properties and corrosion resistance, making it suitable for applications in aerospace, chemical, and medical fields. However, TA4 titanium alloy is relatively expensive, has poor machinability, and is prone to cold welding. Therefore, cold welding must be avoided during machining, and appropriate lubrication and machining methods must be employed. It is widely used in the manufacture of medium- and high-strength, corrosion-resistant parts.

[0005] In existing standard TA4 titanium alloy products: O < 0.4% (0.3% in conventional products), Fe < 0.5% (0.3% in conventional products). In downstream processing industries, the high processing cost of TA4 titanium alloy has always been a pain point, due to the inherent characteristics of titanium alloy materials themselves.

[0006] (1) Poor thermal conductivity means that the cutting heat is not easily dissipated during the cutting process and is concentrated in a small area near the cutting zone and the cutting edge, which leads to increased cutting temperature, faster tool wear, and decreased surface quality.

[0007] (2) It is chemically active and easily reacts with nitrogen and oxygen in the air and carbon in oil at high temperatures to form a hardened layer, which increases cutting resistance and accelerates tool wear.

[0008] (3) Low elastic modulus and large elastic deformation. Titanium alloys have a low elastic modulus, which makes them prone to elastic deformation under cutting force, causing vibration, resulting in reduced machining accuracy and decreased surface quality of titanium alloy parts, and frequent occurrence of abnormalities such as tool breakage.

[0009] In view of this, this disclosure is hereby made.

[0010] Summary of the Invention

[0011] The purpose of this disclosure is to propose a modified titanium alloy with improved machinability. Referring to the existing standard TA4 titanium alloy, the modified alloy increases the variety of metal components and optimizes its microstructure through appropriate forging and rolling processes. This improves the material's hardness and strength without significantly reducing its plasticity and toughness, thereby enhancing its machinability, extending the service life of computer-controlled machining tools, and improving the surface quality of machined products. The mechanical properties and cost of the titanium alloy disclosed herein are comparable to those of the standard TA4 titanium alloy, while the machining cost is lower.

[0012] To solve the above-mentioned technical problems, the present disclosure adopts the following technical solution:

[0013] A modified titanium alloy for improved machinability comprises the following components in weight percentage:

[0014] Al 0.3%–3%, Zr 0.4%–3.0%, Si 0.05%–0.3%, Fe 0.25%–0.5%, O 0.25%–0.4%, with the balance being Ti. Modified titanium alloys also contain unavoidable impurities.

[0015] Optionally, it includes elements in the following mass percentages:

[0016] Al 0.3%–0.5%, Zr 0.4%–1%, Si 0.05%–0.1%, Fe 0.3%–0.4%, O 0.25%–0.35%, balance Ti.

[0017] The method for preparing the modified titanium alloy disclosed herein includes the following steps:

[0018] S1, Ingredients

[0019] Prepare the ingredients according to the required content of each element, including aluminum granules, sponge zirconium, titanium silicon alloy, titanium iron alloy, titanium dioxide, and sponge titanium, and crush each raw material into raw material particles.

[0020] S2. Perform mechanical mixing, electrode pressing, and welding.

[0021] The raw material particles are mechanically mixed, and then the mixed raw material particles are pressed into electrodes and welded using a vacuum plasma welding box.

[0022] S3, Smelting

[0023] The smelting equipment includes electron beam cold hearth smelting apparatus and / or vacuum consumable arc smelting apparatus.

[0024] The smelting process includes electron beam cold bed smelting combined with vacuum consumable arc smelting of the welded electrodes to obtain ingots for later use; or two vacuum consumable arc smelting processes to obtain ingots for later use.

[0025] Optionally, the process also includes a step of processing the ingot to prepare a profile product, including:

[0026] S4, Forging

[0027] The forging temperature range is 800℃~1180℃, and the ingot is forged into a round bar through more than three alternating axial and radial deformations.

[0028] S5, Rolling

[0029] The coils are rolled using a high-speed linear rolling mill and then annealed to remove processing stress and adjust the microstructure.

[0030] S6, precision rolling and drawing

[0031] The annealed coils are processed by precision rolling and drawing to produce profiles, which are then annealed to eliminate processing stress and adjust the microstructure.

[0032] Optionally, in step S1, the particle sizes of each raw material particle are the same or similar, for example, the particle size difference of each raw material particle is ≤4mm; the particle size of sponge titanium is 2mm to 12.7mm, and the particle size of titanium-iron alloy and titanium-silicon alloy is 2mm to 6mm.

[0033] Optionally, step S3 further includes peeling the smelted ingot to remove the surface oxide layer and defects.

[0034] Optionally, after step S4, the bar is further subjected to a peeling process to remove the surface oxide layer and defects.

[0035] Step S5 is followed by a peeling process on the disc to remove the surface oxide layer and defects.

[0036] Optionally, in step S5, the rolling conditions are: infeed temperature 850℃±50℃, rolling line speed 8m / s±3m / s.

[0037] Optionally, in step S5, the annealing temperature is 720℃±20℃, and the holding time is 0.5h~1.5h.

[0038] This disclosure also provides an ingot prepared by a method for preparing a modified titanium alloy as described in any of the foregoing embodiments.

[0039] This disclosure also provides a titanium alloy profile prepared by a method for preparing modified titanium alloy as described in any of the foregoing embodiments.

[0040] Applications of the modified titanium alloys provided by any of the above methods in the fields of electronic products, kitchenware, medical, golf, and anode fixtures.

[0041] Optionally, the application of modified titanium alloys in electronic products includes the manufacture of frames or housings for smart electronic devices, such as frames or housings for mobile phones, tablets, and watches.

[0042] Alternatively, the application of modified titanium alloys in kitchenware includes the manufacture of kitchen utensils for aircraft.

[0043] Alternatively, the applications of modified titanium alloys in the medical field include the fabrication of orthopedic or bone fixation devices.

[0044] Optionally, the application of modified titanium alloys in the golf industry includes their use in the manufacture of golf club heads.

[0045] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0046] The modified titanium alloy disclosed herein is based on the standard TA4 titanium alloy. The addition of trace elements Si, Zr, and Al slightly improves the material's room temperature strength, slightly decreases its plasticity, and enhances its elastic modulus, thermal strength, and creep resistance. Since Al and Si, distributed at grain boundaries, readily precipitate there, and Si and Zr hinder dislocation movement, combined with appropriate forging and rolling processes, an ultrafine-grained microstructure is obtained. Through the combined effect of these elements, the rigidity of the workpiece material during computer-controlled machining is improved, elastic deformation and vibration during machining are suppressed, and tool sticking is reduced. The trace elements segregated at grain boundaries reduce the material's plasticity and improve chip breaking properties during machining. Excellent chip breaking properties allow a large amount of chips to be carried away by the cutting coolant, reducing the hardness reduction and wear of the tool tip caused by material sticking or heat accumulation, thereby extending tool life and improving workpiece machining quality. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 is a metallographic image (200×) of the modified titanium alloy of Embodiment 4 of this disclosure;

[0049] Figure 2 is a binary diagram of the modified titanium alloy of Embodiment 4 of this disclosure;

[0050] Figure 3 shows the metallographic image (200×) of standard TA4 titanium alloy;

[0051] Figure 4 shows the binary diagram of standard TA4 titanium alloy;

[0052] Figure 5 shows the appearance and dimensions of the broken chips during computer-controlled machining of standard TA4 titanium alloy profiles.

[0053] Figure 6 shows the appearance and dimensions of the chip breakage during computer-controlled machining of the modified titanium alloy profile in Embodiment 4 of this disclosure;

[0054] Figure 7 shows the milling cutter diagram (with sticky cutter) during computer-controlled machining of standard TA4 titanium alloy profiles;

[0055] Figure 8 shows the milling cutter diagram (without tool sticking) during the computer-controlled machining of the modified titanium alloy profile in Example 4;

[0056] Figure 9 shows the results of the number of induction cutting force tests for standard TA4 titanium alloy (TA4) and the modified titanium alloy (modified alloy) of Example 4. Detailed Implementation

[0057] The embodiments of this disclosure will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of this disclosure. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0058] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed herein.

[0059] This disclosure provides a modified titanium alloy for improving machinability, comprising the following components in weight percentage:

[0060] Al 0.3%–3%, Zr 0.4%–3.0%, Si 0.05%–0.3%, Fe 0.25%–0.5%, O 0.25%–0.4%, balance Ti.

[0061] This disclosure primarily addresses the issue of mechanical properties in TA4 being comparable to or slightly superior to standard TA4 by adding elements such as Al, Zr, and Si to existing standard alloy compositions, and by selecting appropriate amounts of Fe and O. This improves machinability and reduces processing costs. By enhancing the material's thermal strength, it mitigates tool sticking during machining, reducing cutting resistance. Refining the microstructure inhibits cutting deformation and improves machining stability. The addition of trace elements Al, Zr, and Si adjusts the lubricity and chip-breaking properties during machining (cutting heat is carried away by the cutting fluid with the chips), further reducing cutting resistance and effectively slowing down tool wear caused by chip sticking and insufficient heat dissipation, thus extending tool life.

[0062] In this disclosure, the addition of the α-stabilizing element Al increases the bonding force of the α-solid solution, forming intermetallic compounds with Ti, thereby improving the hot strength of the titanium alloy; it also refines the grains, improving the alloy's elastic modulus and deformation resistance. Al strongly segregates at grain boundaries, with the Al concentration at grain boundaries being more than twice that within the grains. This uneven distribution of Al across grain volume reduces the alloy's plasticity. Considering the overall effect of Al on the alloy's properties, an addition range of 0.3% to 3% is selected, which improves the alloy's strength and elastic modulus, enhances its machinability, and has minimal impact on the material's plasticity.

[0063] Zr is a substitutional neutral strengthening element that forms a continuous solid solution with Ti, lowering the transformation temperature and nucleation activation energy, and promoting silicide nucleation in the matrix. Without reducing the bonding strength of titanium, it strengthens the static lattice distortion of Ti, thus improving the thermal strength of titanium. The addition of Zr allows the α phase to crystallize in more directions, thereby reducing the width of the lath-like α phase and refining the grain size. In coarse-grained structures, the grain boundary area is smaller, making it easier for cutting deformation to propagate along the grain boundaries. In fine-grained structures, the grain boundary area is larger, which can hinder the development of cutting deformation. The Zr compounds precipitated at the grain boundaries act as a lubricant, effectively reducing tool sticking and lowering cutting resistance.

[0064] Si is an interstitial fast eutectoid β-stable element, existing in alloys in solid solution or as silicides. Due to its solid solution strengthening, dynamic strain aging (DSA) effect, and silicide dispersion strengthening, Si improves the creep resistance of titanium alloys. It also refines grains, forming fine, dispersed silicides within the alloy. These silicides distributed at grain boundaries inhibit grain boundary movement and grain growth. Because of the significant difference in atomic size between Si and Ti, Si tends to accumulate at dislocations in the solid solution, hindering dislocation movement, reducing material toughness, and improving chip breaking properties during machining, thereby enhancing the alloy's strength, hardness, and heat resistance. When Si coexists with Zr, it forms dispersed, complex silicides that deposit on active dislocations, impeding dislocation movement and improving the alloy's creep resistance.

[0065] In this disclosure, during the production of titanium alloys, titanium and silicon or iron are added to the titanium alloy as intermediate alloys, such as titanium-silicon alloys and titanium-iron alloys. These alloys are typically produced through smelting. After being crushed into particles, the sponge titanium and other alloying elements are mixed and pressed into electrodes. To ensure the uniformity of the mixture, the particle size difference of all added elements cannot be too large; otherwise, they will agglomerate in certain parts of the electrode block during pressing. Fe tends to segregate in titanium, and the amount of Si added is very small, making mechanical mixing insufficient. Therefore, the selection of intermediate alloys for titanium and silicon or iron during preparation is mainly to ensure the uniformity of the alloy material composition (avoiding segregation) and the consistency of mechanical properties and microstructure.

[0066] The addition of interstitial element O forms an interstitial solid solution with titanium, which leads to lattice distortion, hinders dislocation movement, and plays a role in solid solution strengthening. In addition, it can increase the lattice constant c / a value, reduce its plasticity and toughness, and improve its chip breaking property during cutting.

[0067] Trace amounts of Fe form a substitutional solid solution with titanium, which can refine the grains, improve strength and hardness, and enhance chip breaking properties during cutting.

[0068] The method for preparing profiles from titanium alloy materials disclosed herein includes the following steps:

[0069] Batching - Mechanical mixing - Electrode pressing - Electrode welding - Electron beam cold bed melting (EB melting) once, followed by vacuum self-consuming arc melting (VAR melting) once - Peeling - Forging - Peeling - Rolling - Annealing - Peeling - Profile precision rolling - Profile cold drawing - Annealing.

[0070] Alternatively, the process could be: batching - mechanical mixing - electrode pressing - electrode welding - VAR melting twice - peeling - forging - peeling - rolling - annealing - peeling - profile precision rolling - profile cold drawing - annealing.

[0071] In this method, the preferred melting method is EB melting combined with VAR melting. EB melting has a high temperature and good impurity removal effect. However, two VAR meltings basically meet the requirements in this disclosure. The advantage is that no more equipment is needed, saving costs and time.

[0072] When preparing the ingredients, the following proportions are used: aluminum granules (Al) 0.3%–3%, sponge zirconium (Zr) 0.4%–3.0%, Si (added in the form of titanium-silicon alloy) 0.05%–0.3%, Fe (added in the form of titanium-iron alloy) 0.25%–0.5%, O (added in the form of titanium dioxide) 0.25%–0.4%, and the remainder is sponge titanium.

[0073] During the mechanical mixing process, silicon and iron are crushed into particles and mixed with sponge titanium and other alloying elements before being pressed into electrodes. To ensure the uniformity of the mixture, the particle size difference of all added elements cannot be too large; otherwise, they will agglomerate in certain parts of the electrode block during the electrode pressing process, resulting in uneven mixing.

[0074] Selection of ferro-titanium alloy: Select ferro-titanium alloy with an iron content of 30% to 35% and Ti as the balance, and a particle size of 2 mm to 6 mm (obtained by vacuum induction melting using high-purity iron with a purity > 99.99% and grade 0 sponge titanium; the content requirements of other impurities in the ferro-titanium alloy are: Al < 0.2%, V < 0.1%, Si < 0.1%, C < 0.1%, O < 0.2%).

[0075] Selection of titanium-silicon alloy: Select titanium-silicon alloy with a Si content of 45% to 55% and Ti as the balance, with a particle size range of 2mm to 6mm (obtained by vacuum induction melting using high-purity silicon with a purity >99.999% and grade 0 sponge titanium; the content of other impurities in the titanium-silicon alloy should be: Fe <0.4%, C <0.2%, O <0.2%).

[0076] In the preparation process of the modified titanium alloy disclosed herein, both iron and silicon are added in the form of intermediate alloys with titanium. Titanium-silicon alloys and titanium-iron alloys are typically produced during the smelting process. The choice of adding iron and silicon in alloy form is primarily to ensure the uniformity of the alloy material composition (avoiding segregation) and the consistency of mechanical properties and microstructure. Secondly, Fe tends to segregate in titanium, and the amount of Si added is very small, making it impossible to achieve uniform mechanical mixing.

[0077] Applications of the modified titanium alloys provided by any of the above methods in the fields of electronic products, kitchenware, medical, golf, and anode fixtures.

[0078] In optional embodiments, the application of modified titanium alloys in electronic products includes the manufacture of frames or housings for smart electronic devices, such as frames or housings for mobile phones, tablets, and watches.

[0079] In an alternative embodiment, the application of modified titanium alloys in kitchenware includes the manufacture of kitchenware for aircraft.

[0080] In an alternative embodiment, the application of modified titanium alloys in the medical field includes their use in the fabrication of orthopedic devices or bone fixation devices.

[0081] In an alternative embodiment, the application of modified titanium alloys in the golf industry includes their use in the manufacture of golf club heads.

[0082] All amounts used in the embodiments and comparative examples disclosed herein are nominal amounts, representing allowable reasonable deviations.

[0083] Example 1

[0084] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0085] Al 0.3%, Zr 0.5%, Si 0.05%, Fe 0.25%, O 0.25%, balance Ti.

[0086] Example 2

[0087] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0088] Al 0.5%, Zr 2.0%, Si 0.12%, Fe 0.4%, O 0.35%, balance Ti.

[0089] Example 3

[0090] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0091] Al 0.4%, Zr 1%, Si 0.08%, Fe 0.38%, O 0.32%, balance Ti.

[0092] Example 4

[0093] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0094] Al 0.3%, Zr 0.4%, Si 0.08%, Fe 0.35%, O 0.3%, balance Ti.

[0095] Example 5

[0096] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0097] Al 0.8%, Zr 1.5%, Si 0.15%, Fe 0.3%, O 0.32%, balance Ti.

[0098] Example 6

[0099] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0100] Al 1.0%, Zr 1.8%, Si 0.18%, Fe 0.35%, O 0.35%, balance Ti.

[0101] Example 7

[0102] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0103] Al 1.5%, Zr 2.5%, Si 0.20%, Fe 0.4%, O 0.38%, balance Ti.

[0104] Example 8

[0105] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0106] Al 2.0%, Zr 3.0%, Si 0.25%, Fe 0.45%, O 0.4%, balance Ti.

[0107] Example 9

[0108] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0109] Al 2.5%, Zr 2.8%, Si 0.28%, Fe 0.45%, O 0.35%, balance Ti.

[0110] Example 10

[0111] The modified titanium alloy of this embodiment comprises the following components in weight percentage:

[0112] Al 3.0%, Zr 1.2%, Si 0.3%, Fe 0.5%, O 0.4%, balance Ti.

[0113] Example 11

[0114] The modified titanium alloy materials of Examples 1-10 are used to prepare profiles, including the following steps:

[0115] S1, Ingredients

[0116] Prepare the raw materials according to the requirements of Examples 1-10, including aluminum granules, sponge zirconium, titanium-silicon alloy, titanium-iron alloy, titanium dioxide, and sponge titanium. Crush each raw material, ensuring that the particle size of each raw material is the same or similar. Specifically, use sponge titanium with a particle size range of 2mm-6mm (generally used in aerospace / military product production), and use titanium-iron alloy and titanium-silicon alloy with a particle size range of 2mm-6mm, which is beneficial for uniform mechanical mixing of the materials. The selection criteria for ferro-titanium alloys are as follows: Ferro-titanium alloys with an iron content of 30%–35% and a Ti balance, with a particle size of 2mm–6mm, are selected (obtained by vacuum induction melting using high-purity iron with a purity >99.99% and grade 0 sponge titanium; other impurity content requirements in the ferro-titanium alloy are: Al <0.2%, V <0.1%, Si <0.1%, C <0.1%, O <0.2%). The selection criteria for silicon-titanium alloys are as follows: Silicon-titanium alloys with a Si content of 45%–55% and a Ti balance, with a particle size of 2mm–6mm, are selected (obtained by vacuum induction melting using high-purity silicon with a purity >99.999% and grade 0 sponge titanium; other impurity content requirements in the silicon-titanium alloy are: Fe <0.4%, C <0.2%, O <0.2%). Commercially available materials are selected based on the requirements for ferro-titanium alloys and silicon-titanium alloys.

[0117] S2. Perform mechanical mixing, electrode pressing, and welding.

[0118] The raw material particles are mechanically mixed, and then the pressing of the electrodes and welding are completed.

[0119] S3, VAR Melting

[0120] The vacuum consumable electrode arc melting was performed twice to melt out... The ingots are then peeled to remove surface defects such as pores.

[0121] S4, Forging

[0122] The forging temperature range is 800℃~1180℃, and the ingot is forged into shape through more than three alternating axial and radial deformations. The round bars are then subjected to a peeling process to remove the surface oxide layer and forging defects;

[0123] S5, Rolling

[0124] The coils are rolled using a high-speed linear mill at a feed temperature of 850℃±50℃ and a rolling speed of 8m / s±3m / s. Then, they are annealed at a temperature of 720℃±20℃ for 1 hour to remove processing stress and adjust the microstructure. Finally, they are peeled to remove surface defects and adjust the dimensional accuracy of the coils.

[0125] S6, precision rolling and drawing

[0126] The required profiles are produced through multiple passes of precision rolling and drawing. The profiles are then annealed to eliminate processing stress and adjust their microstructure.

[0127] Three profile samples made of standard TA4 titanium alloy and three profile samples made of modified titanium alloy from three different batches, represented by Example 4, were tested:

[0128] Comparison of hardness test data:

[0129] Comparison of mechanical performance test data:

[0130] Mechanical property test data of standard TA4 titanium alloy

[0131] Mechanical property test data of the modified titanium alloy in Example 4

[0132] Comparison of metallographic structure test data (typical metallographic structure diagram):

[0133] The results are shown in Figures 1-4. Metallographic images show that both the standard TA4 titanium alloy and the modified titanium alloy of Example 4 exhibit uniform equiaxed grain structures. Calculations using metallographic analysis software (Matlab) show that the modified titanium alloy has superior maximum and average grain sizes compared to the standard TA4 titanium alloy. The binary image is a processed image of the metallographic image using metallographic analysis software (Matlab), used for quantitative metallographic analysis. In this disclosure, it is mainly used for determining the grain size (grain size, generally expressed as the number of grains per unit test area). Grain size directly affects the mechanical properties of the material.

[0134] Standard TA4 titanium alloy grain rating data: maximum grain size (μm) 33.660, average grain size (μm) 12.325; modified titanium alloy grain rating data: maximum grain size (μm) 25.670, average grain size (μm) 6.608.

[0135] The grain size data of the modified titanium alloy in Example 4 are as follows:

[0136] The grain size data for standard TA4 titanium alloy are as follows:

[0137] In summary, the modified titanium alloy profile of Example 4 of this disclosure has an average hardness that is more than 10 HV higher than that of the standard TA4 titanium alloy (hardness reaches 273 HV), a yield strength that is about 20 MPa higher than that of the standard TA4 titanium alloy (reaching 641 MPa), a tensile strength that is about 15 MPa higher (reaching 716.67 MPa), and an elongation of about 25%.

[0138] The average grain size reaches grade 11.5, with an average grain size of 6.6 μm. In contrast, the average grain size of TA4 titanium alloy is typically grade 9-10 (GB / T 6394-2002): grade 9 corresponds to an average grain size of 15.9 μm, and grade 10 corresponds to an average grain size of 11.2 μm.

[0139] Furthermore, as shown in Figures 5 and 6, the chip length of the modified titanium alloy in Example 4 is approximately 70% to 80% of that of the standard TA4 titanium alloy.

[0140] In summary, this disclosure alters the properties of titanium alloys by adding elements such as Al, Zr, and Si. For example, the addition of Al increases the hardness and tensile strength of titanium alloys. By controlling the amount of Al added, a new balance is achieved between machining difficulty and milling cutter life, meaning that the increased hardness of titanium alloy materials does not excessively affect the milling cutter life. Generally, increasing the hardness of a material can easily cause thermal deformation during machining, leading to decreased machining accuracy and even other problems. To address this issue, this disclosure improves the thermal strength of titanium alloys by adding Zr, overcoming the deformation resistance of titanium alloys at high temperatures. The addition of Zr also provides lubrication during milling, reducing the bonding force between the milling cutter and chips when machining titanium alloys, thus allowing chips to detach from the milling cutter more easily. The added Si reduces the toughness of titanium alloys to some extent, improving chip breaking properties during cutting. The length of the chips generated during machining is reduced, and shorter chips are easier to separate from the milling cutter. The rapid separation of chips from the milling cutter reduces the contact time between high-temperature chips and the milling cutter, and the chips carry away heat from the milling cutter and machining area, reducing the impact of continuous high heat on the milling cutter, thereby increasing the number of milling operations.

[0141] Therefore, this disclosure makes full use of the effects of the added elements to improve the material properties of the titanium alloy, and strictly controls the amount of each element added to prevent the added elements from increasing the processing difficulty and the cost of the titanium alloy material itself and the processing cost of the titanium alloy. On the contrary, this disclosure reduces the processing difficulty of the material, increases the number of times the milling cutter is used, and reduces the processing cost through the combined effect of the added elements.

[0142] Using the same computer-controlled machining parameters (spindle speed 10000 r / min, feed rate 2 m / min, feed depth 0.6 mm), and the same tools and cutting cooling conditions, the workpiece was machined. Tool life was increased by 10%, meaning that the length / weight of modified titanium alloy machined within the tool life was twice that of standard TA4 titanium alloy. Each 1 m length was considered one milling cycle. The workpiece machining process was monitored by an inductive cutting force measurement and monitoring system installed on the computer-controlled equipment, and the following data was obtained:

[0143] The standard TA4 titanium alloy profiles exhibited a sharp increase in cutting force (greater than 200N, with the second experiment reaching 420N) when machined for the 5th, 48th, and 29th times. Inspection revealed a significant amount of material sticking to the milling cutter head, as shown in Figure 7.

[0144] In Example 4, the modified titanium alloy profile only showed a slight increase in induced cutting force (<150N) throughout the entire processing, and in subsequent processing, the induced cutting force decreased to a stable level (75N~90N), which solved the problem of material sticking to the milling cutter head, as shown in Figure 8.

[0145] As shown in Figure 9, through data comparison, the machinability of the modified titanium alloy in Example 4 is significantly better than that of the standard TA4 titanium alloy. The average induced cutting force during the machining process is about 82% to 90% of that of the standard TA4 titanium alloy, and the stable machining length is 2.5 to 3 times that of the standard TA4 titanium alloy.

[0146] The hardness, strength and elongation of this invention are improved. The Zr-based compounds precipitated at the grain boundaries act as a lubricant between the tool and the material, reducing material sticking to the tool during cutting and reducing the machining load on the tool.

[0147] Machinability results: Reduced machining load, and a 15%-25% reduction in tool tip load.

[0148] After evaluation, the number of machining cycles for the modified titanium alloy of Example 4 was increased: (mass production) 46 times / (modified) more than 100 times, reducing the sticking phenomenon between the tool and the material.

[0149] Since the effects of this disclosure are mainly achieved by adding elements such as Al, Zr and Si, the addition of these elements creates a new balance between the performance and processing difficulty of the titanium alloy, thereby improving the performance of the titanium alloy material while reducing its processing cost. Therefore, based on the same principle, the modified titanium alloys in the other embodiments obviously have similar effects to the modified titanium alloy in Example 4, which has also been confirmed through verification of other embodiments during the research process.

[0150] The above examples demonstrate that adding elements such as Al, Zr, and Si to the titanium alloy of this disclosure can achieve processing properties that are not present in the standard TA4 titanium alloy. Furthermore, by adjusting the amount of different components added during the preparation of the modified titanium alloy material in Example 4, different comparative proportions were obtained to study the effect of the specific amount of each element on the processing properties of the titanium alloy material.

[0151] Comparative Example 1

[0152] The titanium alloy in this comparative example comprises the following components in weight percentage:

[0153] Al 0.27%, Zr 0.4%, Si 0.08%, Fe 0.35%, O 0.3%, balance Ti.

[0154] Comparative Example 2

[0155] The titanium alloy in this comparative example comprises the following components in weight percentage:

[0156] Al 3.3%, Zr 0.4%, Si 0.08%, Fe 0.35%, O 0.3%, balance Ti.

[0157] The addition of Al has a crucial impact on the hardness of titanium alloy materials. Too much or too little Al affects the machinability of titanium alloys. In Comparative Example 1, the Al addition was too low, and the hardness of the titanium alloy material was not significantly improved compared to the standard TA4 titanium alloy (around 265 HV). During machining, the titanium alloy profile was more prone to deformation than the modified titanium alloy profile in Example 4. Furthermore, since Al and Ti can form intermetallic compounds to improve the thermal strength of titanium alloys, insufficient Al addition resulted in insufficient improvement in the thermal strength of the titanium alloy material during machining. The chip length during cutting was similar to that of standard TA4 (measured, the chip length exceeded 1 cm, mostly between 1.1 cm and 1.2 cm), leading to insufficient machinability of the profile. Consequently, the titanium alloy material could not rely on the chips to dissipate heat quickly and in a timely manner during machining, and the number of milling cutter uses did not increase significantly compared to machining standard TA4 titanium alloy profiles, and the milling cutter life was not significantly extended. In Comparative Example 2, the excessive addition of Al led to an excessive increase in the hardness of the titanium alloy (reaching approximately 280 HV). The direct effect was that the excessively hard titanium alloy was too difficult to process. The high hardness resulted in greater heat generation during processing, which in turn affected the milling cutter more significantly. Consequently, the lifespan of the milling cutter was not significantly extended; instead, it caused a sharp reduction in its lifespan due to prolonged operation at high temperatures (approximately 35 machining cycles).

[0158] Comparative Example 3

[0159] The titanium alloy in this comparative example comprises the following components in weight percentage:

[0160] Al 0.3%, Zr 0.36%, Si 0.08%, Fe 0.35%, O 0.3%, balance Ti.

[0161] Comparative Example 4

[0162] The titanium alloy in this comparative example comprises the following components in weight percentage:

[0163] Al 0.3%, Zr 3.3%, Si 0.08%, Fe 0.35%, O 0.3%, balance Ti.

[0164] The addition of Zr not only strengthens the static lattice distortion of Ti and improves its thermal strength, but also acts as a lubricant, effectively reducing tool sticking and lowering cutting resistance. In Comparative Example 3, the amount of Zr added was lower than the 0.4% Zr content in Example 4. The addition of Al increased the hardness of the titanium alloy (the hardness of the titanium alloy reached about 270 HV after Zr strengthening), leading to increased heat during heating. Because the amount of Zr added in Comparative Example 3 was low, the thermal strength of the titanium alloy was insufficient, resulting in weakened strength and defects such as cracks at high temperatures during machining. At the same time, the material lubrication was insufficient during cutting, causing the milling cutter to exhibit a similar sticking phenomenon to that seen in the machining of standard TA4 titanium alloy (the sticking phenomenon was somewhat alleviated compared to machining standard TA4 titanium alloy, but it still existed). In Comparative Example 4, the amount of Zr added was controlled to be higher than 3.0%. As the Zr content in titanium alloy increases, the microstructure first becomes finer and then coarser, the precipitates gradually increase, segregation becomes severe, and the strength first increases and then decreases. Therefore, the excessive addition of Zr in Comparative Example 4 not only resulted in excessive cost, but also reduced strength and decreased toughness during the subsequent processing of the titanium alloy, resulting in low cost-effectiveness.

[0165] Comparative Example 5

[0166] The titanium alloy in this comparative example comprises the following components in weight percentage:

[0167] Al 0.3%, Zr 0.39%, Si 0.045%, Fe 0.35%, O 0.3%, balance Ti.

[0168] Comparative Example 6

[0169] The titanium alloy in this comparative example comprises the following components in weight percentage:

[0170] Al 0.3%, Zr 3.1%, Si 0.33%, Fe 0.35%, O 0.3%, balance Ti.

[0171] In solid solutions, silicon (Si) tends to accumulate at dislocation sites, hindering dislocation movement, reducing material toughness, and improving chip breaking properties during cutting. In Comparative Example 5, the amount of Si added was too small, making its effect insufficient and the improvement in machinability of the titanium alloy material inadequate. However, the addition of Al increased the hardness of the titanium alloy compared to standard TA4 titanium alloy, resulting in greater heat generation during machining. The change in chip length during machining was not significantly different from that of standard TA4 (measured at approximately 1 cm). Heat at the machining location could not be quickly dissipated with the chips, leading to a shorter cutter lifespan compared to machining standard TA4 titanium alloy (approximately 40 machining cycles). In Comparative Example 6, the excessive Si addition reduced the toughness and plasticity of the titanium alloy. Due to the low plasticity of titanium alloy, this significantly affected its plastic deformation during cutting. The deformation coefficient of titanium alloy is only 1 or even less than 1. During cutting, the chip and cutter have a very small contact area, resulting in high pressure and local temperature in the contact area, leading to rapid tool wear and thus negatively impacting cutter lifespan (approximately 42 machining cycles), increasing machining costs.

[0172] Similarly, comparative examples were set up with Fe content below 0.25% and above 0.5%, and O content below 0.25% and above 0.4%. Since appropriate Fe and O content can ensure that the mechanical properties of the material are comparable to or slightly better than those of the standard TA4 titanium alloy, improve machinability, and reduce material processing costs, too much or too little Fe and O content means that the titanium alloy does not have a significant advantage over the standard TA4 titanium alloy in terms of plasticity, toughness, and machinability.

[0173] In summary, the selection of the amounts of Al, Zr, Si, Fe and O in this disclosure has a decisive influence on the processing performance of titanium alloy materials. Each element plays a supporting and complementary role in the processing performance of titanium alloys. Adding too much or too little of a certain element will break this new balance, thereby affecting the processing performance of titanium alloys and failing to achieve the goal of reducing processing costs.

[0174] The above description of the embodiments is provided to enable those skilled in the art to understand and apply this disclosure. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, this disclosure is not limited to the embodiments described herein, and any improvements and modifications made to this disclosure based on its disclosure should be within the scope of protection of this disclosure. Industrial applicability

[0175] This disclosure provides a modified titanium alloy with improved cutting performance, a profile, and a method for preparing the same. It increases the hardness and strength of the material without significantly reducing its plasticity and toughness, improves its cutting performance, extends the service life of computer-controlled machining tools, and improves the surface quality of the machined product. The mechanical properties and cost of the titanium alloy material disclosed herein are comparable to standard TA4 titanium alloy, while the machining cost is lower.

Claims

1. A modified titanium alloy with improved machinability, characterized in that, Including the following elements by mass percentage: Al 0.3%–3%, Zr 0.4%–3%, Si 0.05%–0.3%, Fe 0.25%–0.5%, O 0.25%–0.4%, balance Ti.

2. The modified titanium alloy according to claim 1, characterized in that, Including the following elements by mass percentage: Al 0.3%–0.5%, Zr 0.4%–1%, Si 0.05%–0.1%, Fe 0.3%–0.4%, O 0.25%–0.35%, balance Ti.

3. The method for preparing the modified titanium alloy according to claim 1 or 2, characterized in that, Includes the following steps: S1, Ingredients Prepare the ingredients according to the required content of each element, including aluminum granules, sponge zirconium, titanium silicon alloy, titanium iron alloy, titanium dioxide, and sponge titanium, and crush each raw material into raw material particles. S2. Perform mechanical mixing, electrode pressing, and welding. The raw material particles are mechanically mixed, and then the mixed raw material particles are pressed into electrodes and welded into the smelting equipment; S3, Smelting The smelting equipment includes an electron beam cold bed smelting device and / or a vacuum consumable arc smelting device. The smelting process includes electron beam cold bed smelting combined with vacuum consumable arc smelting of the welded electrodes to obtain ingots for later use; or two vacuum consumable arc smelting processes to obtain the ingots for later use.

4. The method for preparing the modified titanium alloy according to claim 3, characterized in that, The method also includes the step of processing the ingot to prepare profile products, including: S4, Forging The forging temperature range is 800℃~1180℃, and the ingot is forged into a round bar through more than three alternating axial and radial deformations. S5, Rolling The round bar is rolled into a coil using a high-speed linear rolling mill, and then annealed. S6, precision rolling and drawing The annealed coil is then subjected to precision rolling and drawing to produce profiles, which are then annealed to eliminate processing stress and adjust the microstructure.

5. The method for preparing the modified titanium alloy according to claim 3 or 4, characterized in that, In step S1, the particle size difference of each raw material particle is ≤4mm; the particle size of sponge titanium is 2mm to 12.7mm, and the particle size of titanium-iron alloy and titanium-silicon alloy is 2mm to 6mm.

6. The method for preparing the modified titanium alloy according to claim 3 or 4, characterized in that, Step S3 also includes peeling the ingot obtained from smelting to remove the surface oxide layer and defects.

7. The method for preparing the modified titanium alloy according to any one of claims 4 to 6, characterized in that, After step S4, the process further includes peeling the round bar to remove the surface oxide layer and defects; After step S5, the process further includes peeling the disc to remove the surface oxide layer and defects.

8. The method for preparing the modified titanium alloy according to any one of claims 4 to 7, characterized in that, In step S5, the rolling conditions are: infeed temperature 850℃±50℃, rolling line speed 8m / s±3m / s.

9. The method for preparing the modified titanium alloy according to any one of claims 4 to 8, characterized in that, In step S5, the annealing temperature is 720℃±20℃, and the holding time is 0.5h~1.5h.

10. The ingot prepared by the method for preparing the modified titanium alloy according to any one of claims 3, 5-6.

11. Titanium alloy profiles prepared by the method for preparing modified titanium alloys according to any one of claims 4, 7-9.

12. The application of the modified titanium alloy according to claim 1 or 2 in any of the fields of electronic products, kitchenware, medical, golf and anode fixtures.

13. The application according to claim 12, characterized in that, The modified titanium alloy is used in electronic products for the manufacture of any one of the following: frames or shells for mobile phones, tablets, and watches.

14. The application according to claim 12, characterized in that, The modified titanium alloy is used in kitchenware and catering products, including for the manufacture of kitchenware and catering utensils for aircraft.

15. The application according to claim 12, characterized in that, The modified titanium alloy is used in the medical field for the manufacture of orthopedic devices or bone fixation devices.

16. The application according to claim 12, characterized in that, The modified titanium alloy is used in the field of golf, including for manufacturing golf club heads.

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