Low-cost titanium alloy for additive manufacturing and preparation method and application thereof

Abstract

The invention discloses a low-cost titanium alloy for additive manufacturing and a preparation method and application thereof, and relates to the technical field of metal materials. The titanium alloy is prepared from the following components in percentage by mass: 0.1 to 0.5 percent of oxygen, 3.8 to 5.0 percent of iron, 4.0 to 5.0 percent of copper and the balance of titanium and other inevitable impurities. According to the invention, expensive elements such as aluminum (Al), vanadium (V), molybdenum (Mo) and the like are completely abandoned, cheap elements such as Fe, Cu and O are utilized, and excellent room-temperature and high-temperature mechanical properties are obtained while the cost of raw materials is remarkably reduced through the synergistic effect of solid solution strengthening and nanoscale Ti2Cu phase precipitation strengthening.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, specifically to a low-cost titanium alloy for additive manufacturing, its preparation method, and its applications. Background Technology

[0002] Titanium and titanium alloys are widely used in aerospace, biomedical, and other fields due to their high specific strength and excellent corrosion resistance. However, traditional titanium alloys (such as TC4) are expensive, and they suffer from cold cracking sensitivity and element volatilization during powder bed fusion (PBF-LB) additive manufacturing. More importantly, existing low-cost and high-cost titanium alloys struggle to simultaneously achieve good PBF-LB processability and excellent high-temperature performance. TC4 alloys typically operate at temperatures not exceeding 400℃, with significant strength degradation in the 500-600℃ range. While heat-resistant titanium alloys such as Ti-6242S offer good high-temperature performance, they contain large amounts of expensive elements like Sn, Zr, and Mo, resulting in extremely high costs, and their PBF-LB processability is poorly studied. Therefore, developing a dedicated additive manufacturing titanium alloy with a simple composition, low cost, good printing performance, and long-term stable operation below 650℃ has become a pressing issue in this field. Summary of the Invention

[0003] To address the shortcomings of the aforementioned background technology, this invention provides a low-cost titanium alloy for additive manufacturing, its preparation method, and its applications. This alloy achieves high room-temperature strength through ingenious compositional design using inexpensive elements, and is further enhanced by nano-precipitated phases, resulting in excellent high-temperature performance and thermal stability.

[0004] The first objective of this invention is to provide a low-cost titanium alloy for additive manufacturing, comprising the following components in weight percentages: oxygen: 0.1-0.5%, iron: 3.8-4.2%, copper: 4.5-5.0%, and titanium: balance.

[0005] Preferably, the titanium alloy comprises the following components by mass percentage: oxygen: 0.3%, iron: 4.0%, copper: 5.0%, titanium: balance.

[0006] Preferably, the balance also includes unavoidable impurities.

[0007] Preferably, the titanium alloy has a tensile strength of not less than 1100 MPa and an elongation of not less than 5%.

[0008] The second objective of this invention is to provide a method for preparing a low-cost titanium alloy for additive manufacturing, comprising the following steps: According to the composition ratio of titanium alloy, sponge titanium, titanium oxide alloy, titanium iron master alloy and titanium copper master alloy are selected as raw materials. Vacuum consumable arc melting or cold crucible melting technology is used to melt the raw materials into alloy ingots with uniform composition. Alloy ingots are made into spherical powders suitable for the PBF-LB process by inert gas atomization or plasma rotating electrode method; Spherical powder is used to print samples on a PBF-LB device, and then the samples are heat-treated to obtain a low-cost titanium alloy for additive manufacturing.

[0009] Preferably, the particle size of the spherical powder is 15-53 μm.

[0010] Preferably, the heat treatment process involves vacuum annealing at 750~850℃ for 0.5~2 hours.

[0011] The third objective of this invention is to provide an application of low-cost titanium alloys in additive manufacturing.

[0012] The fourth objective of this invention is to provide a three-dimensional solid part, which is made by using spherical powder suitable for PBF-LB process and laser selective melting additive manufacturing process.

[0013] Preferably, the density of the part is not less than 99.5%; The part, whether in the deposited state or after heat treatment, has a room temperature tensile strength of not less than 1100 MPa and an elongation of not less than 5%. The part has a high-temperature tensile strength of not less than 250 MPa at a test temperature of 650℃.

[0014] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a low-cost titanium alloy for additive manufacturing, its preparation method, and its applications. This invention eliminates expensive elements such as vanadium and molybdenum, utilizing inexpensive Fe, Cu, and O elements. Through the synergistic effect of solid solution strengthening and nanoscale Ti₂Cu phase precipitation strengthening, it significantly reduces raw material costs while achieving excellent room-temperature and high-temperature mechanical properties. This alloy is particularly suitable for laser selective melting technology, exhibiting high forming density. Its printed parts show significantly higher room-temperature strength than TC4 alloy. More importantly, it maintains a high strength of over 250 MPa at 650℃, possessing excellent thermal stability and creep resistance, with an upper operating temperature limit of 650℃. This invention provides an ideal material solution for promoting low-cost titanium alloy additive manufacturing technology in medium- and high-temperature fields such as automotive, chemical, and general aviation. This version systematically highlights the comprehensive performance of this titanium alloy at both room temperature and high temperature (650℃), and constructs a complete and convincing technical solution through specific embodiment data, mechanism explanation, and application scenario definition, greatly enhancing the value and scope of protection of the invention. Attached Figure Description

[0015] Figure 1 These are the top view (a) and front view (b) of the three-dimensional solid part prepared in Example 1.

[0016] Figure 2 This is a metallographic image of the PBF-LB molded specimen prepared in Example 1.

[0017] Figure 3 The following are elemental distribution diagrams of the PBF-LB molded specimen prepared in Example 1: (a) High-angle annular dark field diagram; (b) Titanium (Ti); (c) Iron (Fe); (d) Copper (Cu).

[0018] Figure 4 This is a comparison curve of the tensile strength of Example 1 at temperatures ranging from room temperature to 650°C.

[0019] Figure 5 This is a comparison curve of the tensile strength of Comparative Example 1 from room temperature to 650℃. Detailed Implementation

[0020] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0021] The purpose of this invention is to provide a low-cost titanium alloy for additive manufacturing, its preparation method and application, which is a special titanium alloy for additive manufacturing that can work stably for a long time below 650°C.

[0022] To achieve the above objectives, a first aspect of the present invention provides a low-cost titanium alloy for additive manufacturing, the titanium alloy comprising the following components in weight percentage: oxygen: 0.1 to 0.5%, iron: 3.8 to 4.2%, copper: 4.5 to 5.0%, titanium: balance.

[0023] The titanium alloy comprises the following components by weight percentage: oxygen: 0.3%, iron: 4.0%, copper: 5.0%, titanium: balance.

[0024] The balance also includes unavoidable impurities. This titanium alloy has a tensile strength of not less than 1100 MPa and an elongation of not less than 5%.

[0025] The composition design principle of the titanium alloy of this invention is as follows: Low-cost core: Completely abandon expensive elements such as V, Mo, and Zr, and use inexpensive Fe, Cu, and O as the main alloying elements, which can reduce raw material costs by 30%-40% compared to TC4.

[0026] Room temperature strengthening mechanism: O provides interstitial solid solution strengthening; Fe and Cu provide substitutional solid solution strengthening. During the rapid solidification and subsequent thermal processes of PBF-LB, the supersaturation of Fe and Cu provides a prerequisite for precipitation strengthening.

[0027] High-Temperature Strengthening and Thermal Stability Mechanism (Key Innovation): The addition of copper (Cu) is crucial for achieving excellent high-temperature performance. During appropriate heat treatment or thermal cycling in the printing process, Cu can be uniformly dispersed and precipitated in the form of nanoscale Ti₂Cu phase. The Ti₂Cu phase is extremely stable at high temperatures, effectively pinning dislocations and grain boundaries, significantly hindering plastic deformation and creep processes at high temperatures, thereby endowing the alloy with excellent high-temperature strength, creep resistance, and long-term microstructural stability.

[0028] A second aspect of this invention provides a method for preparing a low-cost titanium alloy for additive manufacturing, comprising the following steps: According to the composition ratio of titanium alloy, Ti powder (99.99% purity), TiO2 powder (99.99% purity), Fe powder (99.99% purity) and copper-titanium master alloy powder (99.99% purity) were selected as raw materials; Vacuum consumable arc melting or cold crucible melting technology is used to melt the raw materials into alloy ingots with uniform composition. Alloy ingots are made into spherical powders suitable for the PBF-LB process by inert gas atomization or plasma rotating electrode method; The spherical powder preparation process includes: weighing each component raw material according to mass percentage, sequentially performing vacuum self-consumable melting (three times), forging, secondary precision forging, atomization processing, powder drying once, powder screening, and powder drying twice to obtain spherical powder of Ti-O-Fe-Cu alloy; Forging conditions: peeling forging and billet forging, temperature is 1100℃, vacuum degree of forging is ≤0.15 Pa, and the diameter of the forging is 100 mm; Secondary precision forging conditions: temperature is 960℃, and the bar stock is processed into a diameter of 80 mm and a length of 550 mm using a peeling machine; Atomization processing conditions: Electrode induction melting gas atomization is used, the vacuum degree of atomization processing is ≤0.15 Pa, the pressure is 40±1 bar, the power is 25±1 kW, and the feed rate is 30±1 mm / min; One-time powder drying conditions: temperature 120℃, time 6 h, vacuum degree ≤10 Pa; Powder screening conditions: Use an automatic powder sieve to sieve spherical powder with a particle size of 15-53μm; The conditions for secondary drying of the powder were: temperature 120℃, time 4 h, and vacuum degree ≤10 Pa. Spherical powder was used to print samples on a PBF-LB device. The printing process parameters were: substrate heating temperature 200°C. o C~300 o C, layer thickness 30-40μm, scanning strategy is 67° rotation, printing power is 300W~350W, scanning speed is 1000~1200mm / s, strip width is 7~8mm, strip overlap is -0.01mm.

[0029] The sample was then heat-treated to obtain a low-cost titanium alloy for additive manufacturing. The heat treatment process involved vacuum annealing at 750-850°C for 0.5-2 hours.

[0030] A third aspect of the present invention provides an application of a low-cost titanium alloy in additive manufacturing.

[0031] The fourth aspect of this invention provides a three-dimensional solid part, which is made by using spherical powder suitable for PBF-LB process and laser selective melting additive manufacturing process. The process parameters are as follows: substrate heating temperature is 200℃~300℃, layer thickness is 30-40 μm, scanning strategy is 67° rotation, printing power is 300 W~350 W, scanning speed is 1000~1200 mm / s, strip width is 7~8 mm, and strip overlap is -0.01 mm.

[0032] The density of this part is not less than 99.5%; The part, whether in the deposited state or after heat treatment, has a room temperature tensile strength of not less than 1100 MPa and an elongation of not less than 5%. The part has a high-temperature tensile strength of not less than 250 MPa at a test temperature of 650℃.

[0033] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0034] Example 1 Alloy preparation and powder making: Using Ti powder (99.99%), TiO2 powder (99.99%), Fe powder (99.99%) and copper-titanium master alloy powder (99.99%) as raw materials, the proportions of O: 0.3%, Fe: 4.0%, Cu: 5%, and the balance being Ti were smelted and prepared into PBF-LB special spherical powder (15-53μm).

[0035] PBF-LB forming and heat treatment: Standard mechanical property test specimens were printed on a PBF-LB machine using the above-mentioned powder. The process parameters were as follows: substrate heating temperature 300℃, layer thickness 30 μm, scanning strategy 67° rotation, printing power 300 W, scanning speed 1000 mm / s, strip width 7 mm, strip overlap -0.01 mm, and density 99.7%. The printed specimens were then vacuum annealed at 750℃ for 0.5 hours.

[0036] Room temperature performance test: The heat-treated specimen was subjected to room temperature tensile test, and the results are as follows: tensile strength: 1196.27 MPa, yield strength: 1193.4 MPa, elongation: 11.27%.

[0037] High-temperature performance test results are as follows: 400℃: tensile strength 967.75 MPa, elongation 15.54%; 500℃: tensile strength 1027.29 MPa, elongation 15.95%; 600℃: tensile strength 600.27 MPa, elongation 20.96%; 650℃: tensile strength 294.72 MPa, elongation 55.78%; see Table 1.

[0038] Table 1 shows the high-temperature tensile properties of the Ti-0.3O-4Fe-5Cu alloy in Example 1.

[0039] Example 2 Alloy preparation and powder making: Same as in Example 1, but the composition was adjusted to O: 0.2%, Fe: 4.2%, Cu: 5%.

[0040] PBF-LB forming and heat treatment: The printing process is the same as in Example 1. The printed sample was vacuum annealed at 800°C for 1 hour.

[0041] Room temperature performance test: The mechanical properties of the sample after heat treatment are as follows: tensile strength: 1052.58 MPa, yield strength: 1006.58 MPa, elongation: 13.13%.

[0042] Example 3 Alloy preparation and powder making: Same as in Example 1, but the composition was adjusted to O: 0.1%, Fe: 4.1%, Cu: 5%.

[0043] PBF-LB forming and heat treatment: The printing process is the same as in Example 1. The printed sample was vacuum annealed at 800°C for 1 hour.

[0044] Room temperature performance test: The mechanical properties of the sample after heat treatment are as follows: tensile strength: 1087.09 MPa, yield strength: 744.95 MPa, elongation: 9.07%.

[0045] Comparative Example 1 Alloy preparation and powder making: Same as in Example 1, but the composition was adjusted to O: 0.4% and Fe: 4.1%.

[0046] PBF-LB forming and heat treatment: The printing process is the same as in Example 1. The printed sample was vacuum annealed at 800°C for 1 hour.

[0047] Room temperature performance test: The mechanical properties of the sample after heat treatment are as follows: tensile strength: 1116.54 MPa, yield strength: 1086.02 MPa, elongation: 24.9% Test results: At 400℃: tensile strength 585.23 MPa, elongation 22.29%; at 500℃: tensile strength 442.81 MPa; at 600℃: tensile strength 170.21 MPa; see Table 2.

[0048] Table 2 shows the high-temperature tensile properties of the Ti-0.3O-4Fe alloy in Comparative Example 1.

[0049] In summary, the low-cost titanium alloy provided by this invention not only has significantly better room temperature strength than Ti-O-Fe, but also has a high-temperature strength at 500℃ to 600℃ that is more than 50% higher than that of Ti-O-Fe alloy. At the same time, it has excellent creep resistance and thermal stability, successfully achieving a combination of low cost and high performance.

[0050] To illustrate the relevant properties of the titanium alloy provided by this invention, the accompanying drawings are provided.

[0051] Figure 1 These are (a) top view and (b) front view of the three-dimensional solid part prepared in Example 1. It includes 34 cylindrical rods with a diameter of 9 mm and a height of 60 mm, and a cuboid part with a length of 100 mm, a width of 100 mm, and a height of 60 mm. All parts have high surface quality and high degree of freedom in molding.

[0052] Figure 2 This is a metallographic image of the PBF-LB molded specimen prepared in Example 1. It shows a typical microstructure of primary β phase encapsulating secondary β phase and fine martensitic α phase.

[0053] Figure 3The following are elemental distribution diagrams of the PBF-LB formed specimen prepared in Example 1: (a) High-angle annular dark field image; (b) Titanium (Ti); (c) Iron (Fe); (d) Copper (Cu). It can be seen that the alloy is a dual-phase titanium alloy with both α and β phases, where Fe and Cu are mainly distributed in the β phase.

[0054] Figure 4 This is a comparison curve of the tensile strength of Example 1 from room temperature to 650°C. It was found that the overall strength of the alloy decreased with increasing deformation temperature. However, compared to Comparative Example 1, the Ti-O-Fe-Cu alloy showed higher strength than the Ti-O-Fe alloy. This confirms that adding Cu can yield a low-cost titanium alloy with good high-temperature performance.

[0055] Figure 5 This is a comparison curve of the tensile strength of Comparative Example 1 from room temperature to 650℃. It can be seen that as the deformation temperature increases, the overall strength of the alloy shows a decreasing trend, while the elongation at break gradually increases, exhibiting superplastic characteristics at 650℃.

[0056] This invention describes preferred embodiments and their effects. However, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to include both the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0057] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A low-cost titanium alloy for additive manufacturing, characterized in that, The titanium alloy comprises the following components by mass percentage: Oxygen: 0.1 ~ 0.5%, Iron: 3.8 ~ 4.2%, Copper: 4.0 ~ 5.0%, Titanium: balance.

2. The low-cost titanium alloy for additive manufacturing according to claim 1, characterized in that, The titanium alloy comprises the following components by mass percentage: Oxygen: 0.3%, Iron: 4.0%, Copper: 5.0%, Titanium: Balance.

3. The low-cost titanium alloy for additive manufacturing according to claim 1 or 2, characterized in that, The balance also includes unavoidable impurities.

4. The low-cost titanium alloy for additive manufacturing according to claim 1 or 2, characterized in that, The titanium alloy has a tensile strength of not less than 1100 MPa and an elongation of not less than 5%.

5. A method for preparing a low-cost titanium alloy for additive manufacturing as described in any one of claims 1 to 4, characterized in that, Includes the following steps: According to the composition ratio of titanium alloy, Ti powder, TiO2 powder, Fe powder and copper-titanium master alloy powder are selected as raw materials; Vacuum consumable arc melting or cold crucible melting technology is used to melt the raw materials into alloy ingots with uniform composition. Alloy ingots are made into spherical powders suitable for the PBF-LB process by inert gas atomization or plasma rotating electrode method; Spherical powder is used to print samples on a PBF-LB device, and then the samples are heat-treated to obtain a low-cost titanium alloy for additive manufacturing.

6. The method for preparing a low-cost titanium alloy for additive manufacturing according to claim 5, characterized in that, The particle size of the spherical powder is 15-53 μm.

7. The method for preparing a low-cost titanium alloy for additive manufacturing according to claim 5, characterized in that, The heat treatment process involves vacuum annealing at 750~850℃ for 0.5~2 hours.

8. The application of a low-cost titanium alloy as described in any one of claims 1 to 4 in additive manufacturing.

9. A three-dimensional solid part, characterized in that, The spherical powder used in the PBF-LB process as described in claim 5 is manufactured by laser selective melting additive manufacturing.

10. The three-dimensional solid part according to claim 9, characterized in that, The density of this part is not less than 99.5%; The part, whether in the deposited state or after heat treatment, has a room temperature tensile strength of not less than 1100 MPa and an elongation of not less than 5%. The part has a high-temperature tensile strength of not less than 250 MPa at a test temperature of 650℃.

Images