An easy-to-cut titanium material and its preparation process

Abstract

The present invention discloses an easy-to-cut titanium material and its preparation process, which belongs to the technical field of other processing of metals. The easy-to-cut titanium material includes: a matrix component group and an easy-to-cut component group, and at least one of the easy-to-cut component groups is added to the matrix component group; the matrix component group is calculated by mass percentage as follows: Fe: 0 to 1.0%; N: 0 to 0.08%; H: 0 to 0.02%; O: 0 to 0.50%; Al: 0 to 8.0%; V: 0 to 15.0%, and the balance is titanium and unavoidable impurities; the easy-to-cut component groups are respectively: RE element and S element group, Cu element and S element group, Zr element group, C element group, B element group or Mg element group. The preparation process is to make the aforementioned easy-to-cut titanium material by any one of the three methods of vacuum consumable melting, vacuum levitation melting or powder metallurgy. The present invention solves the technical problem of how to further improve the easy-to-cut performance of titanium materials.

Description

Technical Field

[0001] The present invention relates to the technical field of other processing of metals, and particularly relates to an easily machinable titanium material and a preparation process thereof. Background Art

[0002] Among non-ferrous metals, the performance of metallic titanium is particularly excellent; it is regarded as an important strategic material due to its high specific strength, wear resistance, high temperature resistance, corrosion resistance, etc.; thus, it is widely used in fields such as aerospace, ocean engineering, and the automotive industry. However, when machining titanium materials, the defect of poor cutting performance has always been a major difficulty restricting its engineering applications.

[0003] Specifically, the reasons for the poor cutting performance of titanium materials are mainly reflected in the following aspects: Titanium has high strength and hardness and poor thermal conductivity; the hardening phenomenon generated during its machining is serious. At the same time, due to the high chemical activity of titanium, during the machining process, it reacts with various gases in the air and is prone to form a so-called "structural hardening layer" on the surface; thus, the cutting force exerted on the tool during its cutting is very large, causing severe tool wear and easy tool breakage. In addition, the thermal conductivity coefficient of titanium is low; compared with iron, the thermal conductivity coefficient of titanium is only one-fourth of that of iron; therefore, almost all the heat generated during the cutting of titanium materials exists on the cutting edge of the tool and cannot be discharged, which leads to a high temperature in the cutting area during cutting and severe tool wear. In addition, the elastic modulus of titanium is small, with large deformation and easy springback during its machining, which not only further exacerbates the degree of tool wear; moreover, it will seriously affect the surface accuracy of the machined parts. Further, the friction coefficient between titanium and the tool is large, and the phenomenon of tool sticking is prone to occur during cutting, so that a large amount of heat generated during the cutting of titanium materials is concentrated on the cutting edge, which also exacerbates the degree of tool wear.

[0004] Generally speaking, the foregoing many adverse factors make the cutting performance of titanium materials poor, which not only increases the processing cost of titanium materials, but also makes the accuracy of parts unable to be guaranteed, thus greatly restricting the commercial promotion and application of titanium materials.

[0005] For existing technical solutions, if one wants to solve the technical problem of difficult machining of titanium materials, it is usually possible to start from the following two aspects: improving the processing conditions of titanium materials and alloying titanium materials. Improving the processing conditions of titanium materials means: improving the cutting performance of titanium materials by developing high-performance tool materials and cutting fluids. And alloying titanium materials means: improving its cutting performance by regulating the microstructure of titanium materials. It should be noted that in certain specific application fields of titanium materials, alloying is the only option to improve the cutting performance of titanium materials.

[0006] Based on this, Chinese Patent CN102605212A discloses an easy-to-cut titanium alloy and its preparation method. After mixing Ti, Cu, and Cr powders in a certain proportion, an easy-to-cut titanium alloy is prepared by powder metallurgy. The titanium alloy prepared in this way has the advantages of high strength, low elastic modulus, and excellent cutting performance. The main technical means for improving its cutting performance is to add Cu with high thermal conductivity to the titanium material, and thus generate an easy-to-cut Ti2Cu phase.

[0007] In addition, another Chinese Patent CN102719701A also discloses an easy-to-cut titanium alloy and its preparation method. It prepares a titanium alloy with excellent cutting performance through a vacuum consumable melting method; moreover, this titanium alloy has good fatigue strength and hot working performance. The components of the titanium alloy prepared in this way include elements such as Ti, C, Fe, N, H, Al, V, O, and RE; at the same time, it also adds easy-to-cut components, and the said easy-to-cut components include elements such as Bi, Sn, Te, P, Ni, and S.

[0008] Furthermore, another Chinese Patent CN108097739A also discloses a processing method for an easy-to-cut TC4 alloy wire. First, a TC4 ingot with a nickel content of 0.5%-2% is prepared using sponge titanium, industrial pure aluminum, and wires of titanium-nickel alloy; then, after treatments such as forging, rolling, drawing, and cold drawing, TC4 wire is obtained. After performing corresponding continuous annealing heat treatment on the TC4 wire, an easy-to-cut TC4 titanium alloy wire is obtained. A second-phase particle Ti2Ni is generated in the matrix of this easy-to-cut wire; at the same time, treatments such as large-deformation drawing and continuous annealing also refine its internal structure; thus, it has more excellent cutting performance compared to ordinary TC4 wire.

[0009] Furthermore, another Chinese Patent CN115652141A also discloses a preparation method for a low-cost easy-to-cut antibacterial titanium alloy and a titanium alloy faucet. It prepares an easy-to-cut antibacterial titanium alloy through a vacuum consumable melting method. Its specific chemical composition is: C≤0.05%, H≤0.015%, N≤0.05%, O≤0.2%, Al: 10.0-12.0%, Fe: 6.0-10.0%, Mn: 1.0-3.0%, Mo: 0.1-0.5%, Cu: 4.0-6.0%, Bi: 0.5-1.0%, Sn: 0.6-1.5%, and the balance is Ti and unavoidable impurities. The above titanium alloy is successfully used to manufacture a titanium alloy faucet through negative pressure casting. Through the synergistic effect of brittle Ti3Al compounds, dispersed bismuth particles, and other elements, it has a better easy-to-cut technical effect compared to the ordinary titanium alloy ZTiAl6V4.

[0010] However, the technical solutions disclosed in the existing patents still have technical problems that they cannot significantly improve the machinability of titanium materials or cannot make titanium materials have the advantages of good machinability, low cost, and simple process at the same time. Summary of the Invention

[0011] Based on this, it is necessary to provide an easily machinable titanium material and its preparation process for the technical problem of how to further improve the machinability of titanium materials.

[0012] An easily machinable titanium material, which comprises: a matrix component group and an easily machinable component group, and at least one of the easily machinable component groups is added to the matrix component group;

[0013] The matrix component group is as follows by mass percentage: Fe: 0 - 1.0%; N: 0 - 0.08%; H: 0 - 0.02%; O: 0 - 0.50%; Al: 0 - 8.0%; V: 0 - 15.0%, and the balance is titanium and unavoidable impurities;

[0014] The easily machinable component groups are respectively: a RE element and S element group, a Cu element and S element group, a Zr element group, a C element group, a B element group or a Mg element group;

[0015] In the RE element and S element group, the RE element is an element with atomic numbers 57 - 71 and rare earth alloys composed of them; by mass percentage, the addition amount of the RE element is: 0 - 4.0%, the addition amount of the S element is: 0 - 1.0%, and the mass ratio of the RE element to the S element satisfies: RE element: S element = n: 1, where n = 1 - 4;

[0016] In the Cu element and S element group, the Cu element is added in the form of Cu powder or copper alloy; by mass percentage, the addition amount of the Cu element is: 0 - 4.5%; the addition amount of the S element is: 0 - 1.0%, and the mass relationship between the Cu element and the S element satisfies: Cu = 3S + m, where m = 0 - 1.5%;

[0017] The addition amount of the Zr element group is 0 - 3.0% by mass percentage. In the Zr element group, the Zr element is added in the form of a zirconium-titanium alloy, and the mass relationship between the Zr element and the Ti element satisfies: Zr = 0.048Ti - p, where p = 0 - 2.5%;

[0018] The addition amount of the C element group is 0 - 1.0% by mass percentage; in the C element group, the C element is added in the form of graphite or graphene;

[0019] The addition amount of the B element group is 0 - 0.5% by mass percentage. In the B element group, the B element is added in the form of pure boron or ferroboron alloy;

[0020] The addition amount of the Mg element group is 0 to 1.0% by mass. In the Mg element group, the Mg element is added in the form of a magnesium-iron alloy or a magnesium-aluminum alloy, and the mass relationship between the Mg element and the O element satisfies: Mg = 4O + q, where q = 0 to 0.05%.

[0021] Further, in another embodiment, the matrix component group is as follows by mass percentage: Fe: 0 to 0.500%; N: 0 to 0.050%; H: 0 to 0.015%; O: 0 to 0.400%; Al: 0 to 4.000%; V: 0 to 3.000%; the balance is titanium and unavoidable impurities.

[0022] Further, in another embodiment, in the RE element and the S element group, by mass percentage, the addition amount of the RE element is: 0.5 to 2.4%; the addition amount of the S element is: 0.1 to 1.0%; and the mass ratio between the RE element and the S element satisfies: RE element: S element = n1:1; where n1 = 1.25 to 3.00.

[0023] Further, in another embodiment, in the Cu element and the S element group, by mass percentage, the addition amount of the Cu element is: 0.5 to 2.5%; the addition amount of the S element is: 0.1 to 0.8%, and the mass between the Cu element and the S element satisfies: Cu = 3S + m1; where m1 = 0.1 to 0.9%.

[0024] Further, in another embodiment, by mass percentage, the addition amount of the Zr element group and the addition amount of the Ti element satisfy: Zr = 0.048Ti - p1; where p1 = 0 to 1.3%.

[0025] Further, in another embodiment, the addition amount of the C element group is 0.40 to 0.65% by mass percentage; the addition amount of the B element group is 0.002 to 0.030% by mass percentage.

[0026] Further, in another embodiment, in the Mg element group, by mass percentage, the addition amount of the Mg element and the addition amount of the O element satisfy: Mg = 4O + q1; where q1 = 0 to 0.03%.

[0027] Specifically, in the aforementioned free-cutting titanium material, RE is added in the form of massive or powdered rare earth and rare earth alloys during the raw material mixing process. It can be added with a single element in the rare earth or with a combination of several elements in the rare earth.

[0028] Specifically, in the above-mentioned free-cutting titanium material, the addition medium of S element includes: sublimed sulfur (sulfur powder), ferrosulfur alloy (FeS2, FeS, etc.), MoS2, TiS2 or Cu2S, etc.

[0029] Furthermore, in an embodiment of a specific free-cutting titanium material, by mass percentage, the components are: Ti: 95.5%, La: 0.5%, S: 0.3%, Al: 1.6%, V: 2.0%, Fe: 0.15%, and unavoidable impurities, and the mass ratio of La (RE) to S is 1.67:1.

[0030] Furthermore, in another embodiment of a specific free-cutting titanium material, by mass percentage, the components are: Ti: 95.1%, La: 0.6%, S: 0.3%, Al: 4.0%, and unavoidable impurities, and the mass ratio of La (RE) to S is 2:1.

[0031] Furthermore, in another embodiment of a specific free-cutting titanium material, by mass percentage, the components are: Ti: 95.5%, La: 0.5%, S: 0.4%, Al: 1.5%, V: 2.0%, Fe: 0.15%, and unavoidable impurities, and the mass ratio of La(RE) to S is 1.25:1.

[0032] Furthermore, in another embodiment of a specific free-cutting titanium material, by mass percentage, the components are: Ti: 95.1%, La-Ce composite rare earth: 0.9%, S: 0.35%, Al: 3.2%, V: 0.5%, and unavoidable impurities, and the mass ratio of La+Ce(RE) to S is 2.6:1.

[0033] Furthermore, in another embodiment of a specific free-cutting titanium material, by mass percentage, the components are: Ti: 95.4, La-Ce composite rare earth: 1.6%, S: 0.5%, Al: 1.0%, Cu: 1.5%, B: 0.004%, and unavoidable impurities, and the mass ratio of La+Ce (RE) to S is 3.2:1, and the mass ratio of Cu to S is 3:1.

[0034] Furthermore, in another embodiment of a specific free-cutting titanium material, by mass percentage, the components are: Ti: 92.8%, La-Ce composite rare earth: 2.4%, S: 0.8%, Al: 3.0%, V: 1.0%, B: 0.004%, and unavoidable impurities, and the mass ratio of La+Ce (RE) to S is 3:1.

[0035] Further, in another specific embodiment of the free-cutting titanium material, the components are as follows by mass percentage: Ti: 96.4%, La-Ce composite rare earth: 0.5%, S: 0.15%, Zr: 2.85%, Fe: 0.15%, and unavoidable impurities. The mass ratio of La+Ce (RE) to S is 3.3:1; the mass ratio of Zr to Ti is 0.03:1.

[0036] Further, in another specific embodiment of the free-cutting titanium material, the components are as follows by mass percentage: Ti: 98.9%, Ce: 0.5%, S: 0.15%, C: 0.5%, and unavoidable impurities. The mass ratio of Ce to S is 3.3:1.

[0037] Further, in another specific embodiment of the free-cutting titanium material, the components are as follows by mass percentage: Ti: 95.2%, Mg: 0.8%, O: 0.2%, Al: 1.8%, V: 2.0%, and unavoidable impurities. The mass ratio of Mg to O is 4.1:1.

[0038] Specifically, a process for preparing the aforementioned free-cutting titanium material is realized based on the vacuum consumable process, and it includes the following steps:

[0039] S11: Mixing: Mix the matrix component groups of the free-cutting titanium material according to a preset ratio and put them into a mixer, and perform sufficient stirring to make the components uniform;

[0040] S12: Electrode block preparation: First, pour the uniformly mixed matrix component group materials into the mold barrel of the electrode extruder, and then place the free-cutting component groups of the free-cutting titanium material in the middle of the mold barrel according to a preset ratio; then, use the electrode extruder to extrude the materials in the mold barrel into electrode blocks;

[0041] S13: Consumable electrode preparation: Put the preset number of electrode blocks obtained in step S12 into a vacuum plasma welding box, and under vacuum conditions, use plasma welding to weld all the input electrode blocks into a whole consumable electrode as the anode for vacuum consumable melting;

[0042] S14: First vacuum consumable melting: After clamping the consumable electrode with a holder, put it into a water-cooled copper crucible, evacuate to make the vacuum degree in the furnace less than 3 Pa and then start energizing; after energizing, an arc starts at the end of the electrode, and under the action of high temperature, the electrode begins to melt and the melt drops into the crucible, and the molten pool gradually rises to form an ingot; the melting voltage is set to 20 - 30 V, and the melting current is set to 2 - 6 KA to obtain a preliminarily melted consumable ingot;

[0043] S15: Surface turning of the preliminarily melted consumable ingot: Perform turning processing on the surface of the melted ingot to remove the defective skin, and after processing, obtain a melted titanium ingot with the skin defects removed;

[0044] S16: Multiple smelting: Repeat steps S14 and S15 on the smelted ingot obtained in one time, and refine at least two more times to obtain the refined free-cutting titanium alloy ingot.

[0045] Specifically, another process for preparing the aforementioned free-cutting titanium material is realized based on the vacuum levitation melting process, and it includes the following steps:

[0046] S21: Mixing materials: Mix the raw materials of the matrix component group and the raw materials of the free-cutting component group of the free-cutting titanium material respectively according to the preset ratio and put them into the mixer.

[0047] S22: Feeding materials: Use the feeder to send the raw materials of the matrix component group and the raw materials of the free-cutting component group that have completed mixing into the crucible of the vacuum levitation melting furnace respectively, and place the raw materials of the free-cutting component group in the middle of the crucible, so that the raw materials of the free-cutting component group are wrapped in the middle by the raw materials of the matrix component group.

[0048] S23: Washing gas after vacuum treatment: Vacuum the vacuum levitation melting furnace to below 1×10 -3 Pa, and maintain the preset vacuum degree.

[0049] S24: One-time smelting: Adjust the voltage and current respectively according to the size of the titanium material to be produced, so that the temperature in the furnace rises to 1700 - 2300 °C. After the alloy is completely melted, keep it warm for 10 min to obtain the preliminarily smelted free-cutting titanium ingot.

[0050] S25: Multiple smelting: Turn the preliminarily smelted free-cutting titanium ingot up and down, repeat the furnace charging and smelting, and carry out smelting three times or more to ensure the uniformity of the structure and composition of the titanium ingot.

[0051] Specifically, another process for preparing the aforementioned free-cutting titanium material is realized based on the powder metallurgy process, and it includes the following steps:

[0052] S31: Mixing materials: Mix the raw materials of the matrix component group and the raw materials of the free-cutting component group of the powder free-cutting titanium material according to the ratio and put them into the mixer, and make the particle size of the raw materials of the free-cutting component group similar to that of the raw materials of the matrix component group, and then carry out sufficient stirring to make the components uniform.

[0053] S32: Ball milling treatment: Carry out ball milling and mixing on the mixed powder under the protection of argon, where the ball-to-powder ratio is set to 3:1 - 14:1, and the ball milling time is set to 1 - 6 h.

[0054] S33: Compacting: Compact the raw materials after ball milling under a pressure of 200 - 800 MPa.

[0055] S34: Sintering: After the green compact is formed, the raw material is sintered in a vacuum. The vacuum degree is controlled to be less than 0.1 Pa. It is heated from room temperature to 1000 - 1400 °C at a heating rate of 4 - 10 °C / min; then it is heated to 1150 - 1650 °C at a heating rate of 2 - 5 °C / min and then held for 2 - 3 h.

[0056] S35: Cooling: After the holding is completed, the power is turned off and the raw material is cooled in the furnace. When the furnace cools to 750 °C, an inert gas is introduced into the furnace for air cooling. After air cooling to below 50 °C, a sintered blank of titanium material is obtained.

[0057] In summary, due to its low specific gravity, high strength, wear resistance, high temperature resistance, and corrosion resistance, titanium materials are regarded as important strategic materials and are widely used in fields such as aerospace, ocean engineering, and the automotive industry. However, titanium materials have the defect of poor machinability, which has always been a major difficulty restricting their engineering applications. An easy - to - machine titanium material and its preparation process are proposed in the present invention. By adding one or several groups of easy - to - machine component groups to the matrix composition of titanium materials, the cutting performance of titanium materials can be significantly improved. This kind of easy - to - machine titanium material has the advantages of simple composition design, low cost, simple process, strong operability, and being suitable for the preparation of various titanium materials. Compared with traditional titanium materials, the cutting efficiency of the easy - to - machine titanium material disclosed in the present invention can usually be increased by more than 30%. Therefore, this kind of titanium material not only has good cutting performance but also has good hot - working performance and cold - deformation performance, making it highly applicable. So, an easy - to - machine titanium material and its preparation method in the present invention solve the technical problem of how to further improve the easy - to - machine performance of titanium materials. Brief Description of the Drawings

[0058] Appendix Figure 1 is the metallographic photograph of Example 1 disclosed by an easy - to - machine titanium material of the present invention;

[0059] Appendix Figure 2 is the metallographic photograph of Comparative Example 1 compared with Example 1;

[0060] Appendix Figure 3 is the metallographic photograph of Example 2 disclosed by an easy - to - machine titanium material of the present invention;

[0061] Appendix Figure 4 is the metallographic photograph of Comparative Example 2 compared with Example 2;

[0062] Appendix Figure 5 is the metallographic photograph of Example 3 disclosed by an easy - to - machine titanium material of the present invention;

[0063] Appendix Figure 6 is the metallographic photograph of Comparative Example 3 compared with Example 3;

[0064] AppendixFigure 7 Metallographic photograph of Example 4 disclosed for an easy-to-cut titanium material of the present invention;

[0065] Appended Figure 8 Metallographic photograph of Comparative Example 4 for comparison with Example 4;

[0066] Appended Figure 9 Metallographic photograph of Example 5 disclosed for an easy-to-cut titanium material of the present invention;

[0067] Appended Figure 10 Metallographic photograph of Comparative Example 5 for comparison with Example 5;

[0068] Appended Figure 11 Metallographic photograph of Example 6 disclosed for an easy-to-cut titanium material of the present invention;

[0069] Appended Figure 12 Metallographic photograph of Comparative Example 6 for comparison with Example 6;

[0070] Appended Figure 13 Metallographic photograph of Example 7 disclosed for an easy-to-cut titanium material of the present invention;

[0071] Appended Figure 14 Metallographic photograph of Comparative Example 7 for comparison with Example 7;

[0072] Appended Figure 15 Metallographic photograph of Example 8 disclosed for an easy-to-cut titanium material of the present invention;

[0073] Appended Figure 16 Metallographic photograph of Comparative Example 8 for comparison with Example 8;

[0074] Appended Figure 17 Metallographic photograph of Example 9 disclosed for an easy-to-cut titanium material of the present invention;

[0075] Appended Figure 18 Metallographic photograph of Comparative Example 9 for comparison with Example 9;

[0076] Appended Figure 19 Schematic diagram of a test system for testing the cutting performance of an easy-to-cut titanium material of the present invention;

[0077] Appended Figure 20 Test result graph obtained by performing a cutting force test on Example 1 using the system for cutting performance testing. Detailed implementation manners

[0078] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. Many specific details are set forth in the following description to facilitate a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0079] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0080] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0081] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over", and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below", and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0082] Specifically, an easy-to-cut titanium material of the present invention includes a matrix component group and an easy-to-cut component group. In particular, at least one of the easy-to-cut component groups is added to the matrix component group; the matrix component group, by mass percentage, is: Fe: 0 - 1.0%; N: 0 - 0.08%; H: 0 - 0.02%; O: 0 - 0.50%; Al: 0 - 8.0%; V: 0 - 15.0%, with the balance being titanium and unavoidable impurities; the easy-to-cut component groups are respectively: a rare earth element (RE) and S element group, a Cu element and S element group, a Zr element group, a C element group, a B element group, and a Mg element group.

[0083] Among them, for the RE element and S element group, the RE element is an element with an atomic number of 57 to 71 and rare earth alloys formed by them; by mass, in the RE element and S element group, the content of the RE element is: 0 to 4.0%, and the content of the S element is: 0 to 1.0%, and the mass ratio of the RE element to the S element satisfies: n:1, n = 1 to 4; to ensure that the RE element and the S element can form a stable rare earth sulfide, which is used as an easy-to-cut phase to improve the machinability of titanium materials.

[0084] Specifically, the S element is an easy-to-cut element. Adding the S element to titanium materials is beneficial to increasing the chip breakability of chips, thereby improving the cutting performance of titanium materials. The mechanism by which adding sulfur alone can improve the machinability of titanium materials is as follows: S combines with Ti to form an easy-to-cut phase TiS2. As the content of the S element in titanium materials increases, the number of TiS2 increases significantly, which will increase the hot brittleness of titanium materials and is beneficial to cutting chip breakage; at the same time, TiS2 can also improve the heat conduction ability of titanium materials to improve the cutting working conditions.

[0085] More specifically, the addition media of the S element include: sublimed sulfur (sulfur powder), ferrosulfur alloys (FeS2, FeS, etc.), MoS2, TiS2, and Cu2S, etc.

[0086] Specifically, the RE element is added in the form of massive or powdered rare earth and rare earth alloys during the raw material melting process. The RE element can be added individually as one of La, Ce, Pr, and Nd, or several of them can be added in combination; the combined addition of the RE element and the S element can form a rare earth sulfide between the RE element and the S element.

[0087] The mechanism by which the combination of the RE element and the S element improves the machinability of titanium materials is as follows: rare earth and sulfur can form rare earth sulfides, and these rare earth sulfides have relatively fixed ratios, which are beneficial to chip breakage during cutting and can improve the heat conduction ability of titanium materials. When the contents of both the RE element and the S element are low, the rare earth sulfide will precipitate in the form of small granular spheres at the grain boundaries and the number is small, and the improvement effect on the cutting performance of titanium materials is weak; when the contents of the RE element and the S element increase, the rare earth sulfide will precipitate in the form of cluster-like spheres at the grain boundaries and within the grains, with larger sizes, and has an obvious promoting effect on the machinability of titanium materials; when the contents of the RE element and the S element are further increased, the improvement of the cutting of the material is limited, but the negative effect on the material increases significantly.

[0088] Specifically, through metallographic analysis, it is found that when the content of RE element is 0-4.0% and the content of S element is 0-1.0%; and when the mass ratio of RE element to S element satisfies n:1 (n = 1-4), that is, when added according to the RE content, S content, and the mass ratio of RE to S proposed in the present invention; rare earth sulfides can be more evenly distributed in the titanium material, with a spherical morphology, a large number, and small sizes. These evenly distributed rare earth sulfides are beneficial to the generation of titanium chips and the segmentation effect, significantly improving the cutting performance of the titanium material and having no significant impact on other properties of the titanium material.

[0089] Furthermore, for the Cu element and S element group, the Cu element is added in the form of Cu powder or copper alloy; and, by mass, the content of the Cu element is 0-4.5%; the content of the S element is 0-1.0%, and the mass of the Cu element and the S element satisfies Cu = 3S + m, where m = 0-1.5%; to ensure that Cu and S elements can form CuTi2 and Cu2S compounds in the titanium material. These compounds can serve as free-cutting phases to improve the thermal conductivity of the titanium material and enhance the hot workability and machinability of the material.

[0090] Specifically, the reason for the addition of the Cu element to improve the machinability of the titanium material is that Cu itself has a high thermal conductivity. Adding Cu to the titanium material is beneficial to the conduction of heat in the cutting zone during the cutting process; when Cu and S are added in combination, easy-cutting phases conducive to cutting will be formed between them. Adding Cu to the titanium material will form a brittle phase: Ti2Cu, and the Ti2Cu phase can serve as a chip-breaking origin, thereby improving the cutting processability of the titanium material.

[0091] It should be noted that when the addition amount of Cu is low, fewer CuTi2 and Cu2S compounds are formed in the titanium material, and there is no obvious effect on the improvement of the cutting performance of the titanium material; with the further increase of the Cu content, when the copper content is 0-4.5%; the sulfur content is 0-1.0%, and the mass of Cu and S satisfies Cu = 3S + m, where m = 0-1.5%, that is, when added according to the Cu content, S content, and the mass ratio of Cu to S disclosed in the present invention, stable and uniform CuTi2 and Cu2S compounds will be formed in the titanium material. These compounds not only enhance the thermal conductivity of the titanium material but also increase the chip segmentation rate during the cutting process of the titanium material, significantly improving the cutting performance of the titanium material and having little impact on other properties of the titanium material. When the contents of Cu and S are further increased, a large amount of CuTi2 and Cu2S compounds will precipitate in the titanium material and aggregate and distribute in the titanium material, which will seriously deteriorate the high-temperature performance of the titanium material.

[0092] Furthermore, for the Zr element group, the content of the Zr element group is: 0~3.0% by mass, wherein the Zr element is added in the form of zirconium-titanium alloy, and the Zr element and the Ti element satisfy: Zr=0.048Ti-p, wherein: p=0~2.5%, ensuring that the Zr element can be effectively dissolved in the titanium material and precipitated at the grain boundary; thereby, the hot working performance and cutting machinability of the titanium material can be improved.

[0093] Specifically, Zr can be dissolved in titanium, the relative atomic mass of Zr is 91.2, and the relative atomic mass of Ti is 47.9; therefore, in order to make Zr completely dissolved in titanium, and the excess Zr atoms precipitate in the titanium material in the form of ZrTi compounds, the mass between Zr and Ti should satisfy: 47.9Zr*40=91.2Ti-p, where: p=0~2.5%; when the Zr addition amount is low, Zr is completely dissolved in Ti, and has no effect on improving the cutting performance of titanium; when the Zr content is high, ZrTi compounds precipitate in large quantities, which is actually detrimental to the cutting performance of titanium.

[0094] Furthermore, for the C element group, the content of the C element group is 0-1.0% by mass; C is added in the form of graphite or graphene, and C is precipitated in the titanium material in the form of TiC as a precipitated phase. Therefore, during the high-temperature hot working process, the grain boundaries can be pinned and the grains can be refined to improve the thermal conductivity of the titanium material, thereby improving the machinability of the titanium material.

[0095] When the C content is low, C is dissolved in Ti and fails to form TiC precipitation phase, which does not improve the cutting performance of titanium. When the C content is high, a large number of TiC inclusions will be formed in the titanium material and aggregated and distributed in the titanium material, which seriously affects the plasticity of the titanium material and embrittles the titanium material; at the same time, it will aggravate the wear of the tool during the cutting process. When the addition amount of C is 0-1.0%, TiC can be precipitated more evenly in the titanium material. A large amount of fine TiC can not only improve the thermal conductivity of the titanium material, but also has the effect of pinning the grain boundary and refining the grain, which is beneficial to improve the cutting performance of the titanium material.

[0096] Furthermore, for the B element group, the content of the B element group is 0 to 0.5% by mass. B is added in the form of pure boron or ferroboron alloy to ensure that B atoms can be dissolved in the titanium material, thereby inhibiting the grain growth behavior of the titanium material during high-temperature hot working, and playing a role in refining the grains and uniform organization, so as to improve the machinability of the titanium material.

[0097] Specifically, B can be dissolved in titanium. Therefore, when the amount of B added is low, B is completely dissolved in titanium, and the cutting performance cannot be improved ideally. When the amount of B added is too high, a large amount of hard borides TiB and TiB2 will precipitate, further deteriorating the cutting performance of titanium and increasing tool wear. When the amount of boron added is 0-0.5%, on the one hand, it can ensure that B atoms can be dissolved in titanium, and on the other hand, it can also make borides dispersed and precipitated in titanium, which not only has the effect of pinning grain boundaries, refining and homogenizing the structure, but also can improve the cutting performance of titanium.

[0098] Furthermore, for the Mg element group, the content of the Mg element group is: 0-1.0%, calculated by mass, wherein the Mg element is added in the form of magnesium-iron alloy or magnesium-aluminum alloy, and the amount of Mg element added satisfies: Mg=4O+q, wherein q=0-0.05%, to ensure that MgO can be formed during the titanium material smelting process, and MgO serves as a dispersed precipitate phase, thereby improving the cutting and breaking properties of the material, increasing the heat transfer properties, and thereby improving the cutting properties of the titanium material.

[0099] Specifically, when the amount of Mg added is too high, a large amount of large-sized and aggregated MgO will be formed in the titanium material, which will reduce the cutting segmentation of the titanium material. At the same time, the cleanliness of the titanium material will be reduced, which will seriously deteriorate the mechanical properties of the titanium material. When the amount of Mg added is low, Mg is completely dissolved in the titanium material and cannot be used as an easy-to-cut phase to improve the cutting performance of the titanium material. Therefore, when the amount of Mg added is 0-1.0%, and the amount of Mg added satisfies: Mg=4O+q, where q=0-0.05%, Mg can combine with O to form MgO. At this time, MgO is dispersed in the titanium material, and as an easy-to-cut phase, the chip breakage of the titanium material is significantly improved; at the same time, the thermal conductivity of the titanium material is increased, thereby improving the cutting performance of the titanium material.

[0100] Furthermore, the aforementioned free-cutting titanium material can be manufactured by any one of the following three methods: vacuum consumable melting, vacuum suspension melting and powder metallurgy.

[0101] Specifically, when the aforementioned free-cutting titanium material is prepared by vacuum consumable smelting, the preparation process includes the following steps:

[0102] S11: Mixing: Mix the matrix component group of the free-cutting titanium material according to a preset ratio and put it into a mixer, and stir it thoroughly to make the components uniform;

[0103] S12: Preparation of electrode block: firstly pour the materials of the matrix component group after being mixed evenly into the die barrel of the electrode extruder, and then place the free-cutting component group of the free-cutting titanium material in the middle of the die barrel according to a preset ratio; then, use the electrode extruder to extrude the materials in the die barrel into an electrode block;

[0104] S13: Preparation of consumable electrode: Put the preset number of electrode blocks in step S12 into a vacuum plasma welding box. Under vacuum conditions, use plasma welding to weld all the input electrode blocks into a whole consumable electrode, serving as the anode for vacuum consumable melting.

[0105] S14: Primary vacuum consumable melting: After clamping the consumable electrode with a gripper, put it into a water-cooled copper crucible. Evacuate to make the vacuum degree in the furnace less than 3 Pa and then start power-on; after power-on, an arc starts at the end of the electrode. Under the action of high temperature, the electrode begins to melt and the melt drops into the crucible. The molten pool gradually rises and then forms an ingot; the melting voltage is set to 20 - 30 V, and the melting current is set to 2 - 6 KA to obtain a preliminarily melted consumable ingot.

[0106] S15: Turning the surface of the preliminarily melted consumable ingot: Carry out turning processing on the surface of the melted ingot to remove the defective skin, and after treatment, obtain a melted titanium ingot with the skin defects removed.

[0107] S16: Multiple melting: Repeat steps S14 and S15 for the melted ingot obtained once, and refine at least 2 more times to obtain a refined free-cutting titanium alloy ingot. Specifically, multiple melting is a further refinement based on the primary melting, in order to improve the uniformity of alloying elements in the titanium alloy ingot and remove the impurity elements on the surface to ensure the consistency of the material.

[0108] Further, when preparing the aforementioned free-cutting titanium material by the method of vacuum levitation melting, its preparation process includes the following steps:

[0109] S21: Mixing materials: Mix the matrix component groups of the free-cutting titanium material according to the preset ratio and put them into a mixer.

[0110] S22: Feeding materials: Use a feeder to send the raw materials of the matrix component group after mixing and the raw materials of the free-cutting component group of the free-cutting titanium material with the preset ratio into the crucible of the vacuum levitation melting furnace, and place the raw materials of the free-cutting component group in the middle of the crucible so that it is wrapped in the middle by the raw materials of the matrix component group.

[0111] S23: Washing gas after vacuum treatment: Evacuate the vacuum levitation melting furnace to below 1×10 -3 Pa, and maintain the preset vacuum degree.

[0112] S24: Primary melting: According to the size of the titanium material to be prepared, adjust the voltage and current respectively to raise the temperature in the furnace to 1700 - 2300 °C. After the alloy is completely melted, keep it warm for 10 min to obtain a preliminarily melted free-cutting titanium ingot.

[0113] S25: Multiple smelting: Turn the initially smelted free-cutting titanium ingot over, repeat charging and smelting, and conduct smelting three times or more to ensure the uniformity of the structure and composition of the titanium ingot.

[0114] Further, when preparing the aforementioned free-cutting titanium material by powder metallurgy, its preparation process includes the following steps:

[0115] S31: Mixing: Mix the raw materials of the matrix component group and the free-cutting component group of the powder-shaped free-cutting titanium material in proportion and put them into a mixer, and make the particle size of the free-cutting component group as close as possible to that of the raw materials of the matrix component group, and conduct sufficient stirring to make the components uniform;

[0116] S32: Ball milling treatment: Conduct ball milling and mixing on the mixed powder under the protection of argon, where the ball-to-material ratio is set to 3:1 - 14:1, and the ball milling time is set to 1 - 6 h;

[0117] S33: Compacting: Compact the ball-milled raw materials under a pressure of 200 - 800 MPa;

[0118] S34: Sintering: Conduct vacuum sintering on the raw materials after compacting, and control the vacuum degree to be less than 0.1 Pa; Heat it from room temperature to 1000 - 1400 °C at a heating rate of 4 - 10 °C / min; Then heat it to 1150 - 1650 °C at a heating rate of 2 - 5 °C / min and hold for heat preservation, and the heat preservation time is 2 - 3 h;

[0119] S35: Cooling: After the heat preservation is completed, turn off the power supply and let the raw materials cool in the furnace. When the furnace cools to 750 °C, introduce inert gas into the furnace for air cooling, and after air cooling to below 50 °C, obtain the sintered blank of the titanium material.

[0120] Specifically, RE, S, Cu, Zr, C, B, and Mg disclosed in a free-cutting titanium material and its preparation process of the present invention are all elements beneficial to cutting, and the addition of these elements to the titanium material is beneficial to improving the cutting performance of the titanium material.

[0121] Particularly, in an embodiment of a free-cutting titanium material of the present invention, the matrix component group is further optimized by mass percentage as follows: Fe: 0 - 0.5%; N: 0 - 0.05%; H: 0 - 0.015%; O: 0 - 0.4%; Al: 0 - 4.0%; V: 0 - 3.0%; the balance is titanium and unavoidable impurities. In addition to the above components, it should also contain one or more free-cutting component groups.

[0122] Particularly, in another embodiment of the free-machining titanium material of the present invention, as a free-machining titanium material containing RE and S, the RE and S are further optimized by mass percentage as follows: the RE content is 0.5 - 2.4%; the S element content is 0.1 - 1.0%; and the mass of RE and S should satisfy: RE:S = n1:1, where n1 = 1.5 - 3.0.

[0123] Particularly, in another embodiment of the free-machining titanium material of the present invention, as a free-machining titanium material containing Cu and S, the Cu and S are further optimized by mass percentage as follows: Cu: 0.5 - 2.5%; S: 0.1 - 0.8%, and the mass of Cu and S satisfies: Cu = 3S + m1, where m1 = 0.1 - 0.9%.

[0124] Particularly, in another embodiment of the free-machining titanium material of the present invention, as a free-machining titanium material containing Zr, the addition amount of Zr and Ti satisfies: Zr = 0.048Ti - p1, where p1 = 0 - 1.3%, to ensure that Zr can be effectively dissolved in the titanium material and precipitate at the grain boundaries.

[0125] Particularly, in another embodiment of the free-machining titanium material of the present invention, as a free-machining titanium material containing C, the mass percentage of the C element is further optimized as: C: 0.40 - 0.65%, to ensure that C precipitates in the form of TiC in the titanium material and can pin the grain boundaries and refine the grains during the high-temperature hot working process.

[0126] Particularly, in another embodiment of the free-machining titanium material of the present invention, as a free-machining titanium material containing B, the mass percentage of the B element is further optimized as: B: 0.002 - 0.030%.

[0127] Particularly, in another embodiment of the free-machining titanium material of the present invention, as a free-machining titanium material containing Mg, the mass percentage of Mg is further optimized as: the mass of Mg and O satisfies: Mg = 4O + q1, where q1 = 0.01 - 0.03%.

[0128] Furthermore, by mass percentage, the following respectively disclose 9 specific embodiments and 9 corresponding comparative examples, as shown in Table 1 below:

[0129] Table 1: Chemical compositions of different embodiments and comparative examples

[0130]

[0131] It should be noted that in the above Table 1, * represents the added La content; ** represents the combined addition amount of La - Ce; *** represents the added Ce content; the smelting method used in each embodiment and comparative example is the vacuum consumable melting method.

[0132] Further, the following method was used to perform performance tests on the examples and comparative examples in Table 1 disclosed in the present invention. The cutting effects of the examples and comparative examples are shown in Table 2 below.

[0133] Hardness test: The MH-5L micro-Vickers hardness tester was used to perform hardness tests on the examples and comparative examples, with a total of 10 tests. The average hardness value was selected as the final test result.

[0134] Cutting performance test: The milling cutter was a standard cutter for titanium alloy cutting with a diameter of 4 mm - D0101.002027. The cutting fluid was a microemulsion cutting fluid for titanium alloy. The rotational speed was 5000 rev / min, the feed rate was 800 mm / min, the cutting depth was 4 mm, and the side cutting depth was 0.4 mm. The cutting performance test was carried out on a V-8L machining center, and the Kistler 9257B dynamometer was used to collect the cutting force during the milling process.

[0135] Specifically, please refer to the appendix Figure 19 , a system for cutting performance test, which includes a test machining center 1, a standard titanium alloy milling cutter 2, a fixture 3, a dynamometer 4, a charge amplifier 5, a data acquisition system 6, and a computer 7; the test machining center 1 is provided with the standard titanium alloy milling cutter 2, the fixture 3, and the dynamometer 4 respectively, and the dynamometer 4 is connected below the fixture 3. The charge amplifier 5 is connected to the dynamometer 4 through a connecting cable; the data acquisition system 6 is respectively connected to the charge amplifier 5 and the computer 7. Thus, in the experiment of cutting performance test, the test machining center 1 drives the standard titanium alloy milling cutter 2 to perform milling on the titanium sample clamped on the fixture 3 according to the preset processing parameters; at this time, the dynamometer 4 can collect the cutting force during the milling process; after being processed by the charge amplifier 5 and the data acquisition system 6, the data is then transmitted to the computer 7 for processing. Please continue to refer to the appendix Figure 20 , which shows the cutting force test results obtained after performing the milling performance test on Example 1 using the aforementioned system for cutting performance test.

[0136] The performance test results of the examples and comparative examples are shown in Table 2; the metallographic photos of the examples and comparative examples after grinding and polishing are shown in Appendix Figure 1 to Appendix Figure 18 as shown. Compared with the corresponding comparative examples, the titanium materials in the examples disclosed in the present invention introduce easy-cutting phases beneficial to cutting after alloying, significantly improving the cutting performance of the titanium materials.

[0137] Table 2: Cutting effects of the examples and comparative examples

[0138]

[0139] As can be seen from the test results in Table 2, after adding free-cutting components, the cutting performance of titanium materials can be significantly improved. Among them, the calculation method of the cutting force improvement rate revealed in Table 2 is: cutting force improvement rate (%) = (cutting force of the comparative example - cutting force of the example) / cutting force of the comparative example × 100%.

[0140] In summary, titanium materials are regarded as important strategic materials due to their low specific gravity, high strength, wear resistance, high temperature resistance, and corrosion resistance, and are widely used in fields such as aerospace, ocean engineering, and the automotive industry. However, titanium materials have the defect of poor machining performance, which has always been a major difficulty restricting their engineering applications. The present invention of a free-cutting titanium material proposes a free-cutting titanium material and its preparation process. By adding one or several groups of free-cutting component groups to the matrix composition of titanium materials, the cutting performance of titanium materials can be significantly improved. This free-cutting titanium material has the advantages of simple composition design, low cost, simple process, strong operability, and is suitable for the preparation of various titanium materials. Compared with traditional titanium materials, the cutting efficiency of the free-cutting titanium material disclosed in the present invention can usually be increased by more than 30%. Therefore, this kind of titanium material not only has the advantage of good cutting performance, but also has good hot workability and cold deformation performance, making it highly applicable. Therefore, the present invention of a free-cutting titanium material and its preparation method solves the technical problem of how to further improve the free-cutting performance of titanium materials.

[0141] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0142] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A free-cutting titanium material, characterized in that: It includes: Base component group and free-cutting component group; The matrix component group is calculated by mass percentage as follows: Fe: 0-1.0%; N: 0-0.08%; H: 0-0.02%; O: 0-0.50%; Al: 0-8.0%; V: 0-15.0%, the balance is titanium and unavoidable impurities; The free-cutting component group includes RE elements and S elements. In addition, the free-cutting component group also includes at least one of the Cu element and S element group, the Zr element group, the C element group or the B element group; In the RE element and S element group, the RE element is a composite rare earth component composed of two or more elements with atomic numbers of 57 to 71; in terms of mass percentage, the addition amount of the RE element is: 0.5 to 2.4%, the addition amount of the S element is: 0.1 to 1.0%, and the mass ratio of the RE element to the S element satisfies: RE element:S element=n1:1; wherein n1=1.25 to 3.20; In the Cu element and S element group, the Cu element is added in the form of Cu powder or copper alloy; in terms of mass percentage, the added amount of the Cu element is: 0.5-2.5%; the added amount of the S element is: 0.1-0.8%, and the mass ratio of the Cu element and the S element satisfies: Cu=3S+m1; wherein m1=0-1.5%; The addition amount of the Zr element group is calculated as 0-3.0% by mass percentage. In the Zr element group, the Zr element is added in the form of zirconium-titanium alloy, and the mass relationship between the Zr element and the Ti element satisfies: Zr=0.048Ti-p, wherein p=0-2.5%; The addition amount of the C element group is calculated by mass percentage: 0-1.0%; in the C element group, the C element is added in the form of graphite or graphene; The addition amount of the B element group is 0-0.5% by mass percentage; in the B element group, the B element is added in the form of pure boron or ferroboron alloy.

2. A process for preparing a free-cutting titanium material as claimed in claim 1, characterized in that: It is realized based on vacuum consumable process, which includes the following steps: S11: Mixing: Mix the matrix component group of the free-cutting titanium material according to a preset ratio and put it into a mixer, and stir it thoroughly to make the components uniform; S12: Preparation of electrode block: firstly pour the materials of the matrix component group after being mixed evenly into the die barrel of the electrode extruder, and then place the free-cutting component group of the free-cutting titanium material in the middle of the die barrel according to a preset ratio; then, use the electrode extruder to extrude the materials in the die barrel into an electrode block; S13: Preparation of consumable electrode: placing a preset number of electrode blocks obtained in step S12 into a vacuum plasma welding box, and welding all the electrode blocks into a whole consumable electrode by plasma welding under vacuum conditions, which serves as an anode for vacuum consumable smelting; S14: primary vacuum consumable melting: after clamping the consumable electrode with a clamp, put it into a water-cooled copper crucible, evacuate the furnace until the vacuum degree is less than 3Pa, and then start to power on; after power on, an arc is generated at the end of the electrode, and the electrode begins to melt under the action of high temperature and the melt drips into the crucible, and the molten pool gradually rises to form an ingot; the melting voltage is set to 20-30V, and the melting current is set to 2-6KA, to obtain a primary smelted consumable ingot; S15: Surface turning of the primary smelting consumable ingot: turning the surface of the smelted ingot to remove the surface skin containing defects, and obtaining a smelted titanium ingot with the surface defects removed after the processing; S16: Multiple smelting: The smelted ingot obtained once is subjected to steps S14 and S15 again, and refined at least twice more to obtain a refined free-cutting titanium alloy ingot.

3. A process for preparing a free-cutting titanium material as claimed in claim 1, characterized in that: It is realized based on vacuum suspension melting process, which includes the following steps: S21: Mixing: Mixing the raw materials of the matrix component group of the free-cutting titanium material and the raw materials of the free-cutting component group according to a preset ratio and putting them into a mixer; S22: feeding: using a feeder to feed the mixed raw materials of the matrix component group and the raw materials of the free-cutting component group into the crucible of the vacuum suspension melting furnace respectively, and placing the raw materials of the free-cutting component group in the middle of the crucible, so that the raw materials of the free-cutting component group are wrapped in the middle by the raw materials of the matrix component group; S23: Vacuum treatment and post-gas washing: evacuate the vacuum suspension melting furnace to 1×10 -3 Pa or less, maintain the preset vacuum degree; S24: primary smelting: according to the size of the titanium material to be produced, the voltage and current are adjusted respectively to raise the temperature in the furnace to 1700-2300°C. After the alloy is completely melted, the temperature is kept for 10 minutes to obtain a primary smelted free-cutting titanium ingot; S25: Multiple smelting: The primary smelted free-cutting titanium ingot is turned upside down and repeatedly loaded into the furnace for smelting. The smelting is performed three times or more to ensure that the structure and composition of the titanium ingot are uniform.

4. A process for preparing a free-cutting titanium material as claimed in claim 1, characterized in that: It is realized based on powder metallurgy process, which includes the following steps: S31: Mixing: Mix the raw materials of the matrix component group of the free-cutting titanium material in powder form with the raw materials of the free-cutting component group in proportion and put them into a mixer, and make the particle size of the free-cutting component group raw materials close to that of the matrix component group raw materials, and then stir them sufficiently to make the components uniform; S32: ball milling: ball milling the mixed powder under the protection of argon, wherein the ball-to-material ratio is set to 3:1-14:1, and the ball milling time is set to 1-6 hours; S33: green compacting: green compacting the ball-milled raw material under a pressure of 200 to 800 MPa; S34: Sintering: After the green sheet is pressed, the raw material is subjected to vacuum sintering, and the vacuum degree is controlled to be less than 0.1 Pa; the temperature is raised from room temperature to 1000-1400°C at a heating rate of 4-10°C / min; then the temperature is raised to 1150-1650°C at a heating rate of 2-5°C / min and then kept warm for 2-3 hours; S35: Cooling: After the insulation is completed, the power is turned off to allow the raw materials to cool in the furnace. When the furnace is cooled to 750°C, inert gas is introduced into the furnace for air cooling. After the temperature is cooled to below 50°C, a titanium sintered billet is obtained.

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