High-toughness titanium alloy for deep sea equipment additive manufacturing

Abstract

The invention discloses a high strength and toughness titanium alloy for deep sea equipment additive manufacturing, which is composed of the following components in percentage by mass: 4.8-5.5% of Al, 2.8-3.2% of Mo, 2.5-3.5% of V, 2.8-3.2% of Cr, 1.5-2.5% of Zr, 0.8-1.2% of Nb and the balance of Ti and inevitable impurity elements, and satisfies the following conditions: 0.765 < = B0 < = 0.767, 2.374 < = Md < = 2.385. The Al, Mo, V, Cr, Zr and Nb elements are added, the contents of the Al, Mo, V, Cr, Zr and Nb elements are controlled, B0 and Md are reasonably matched, control over a structure performance regulation window after alloy additive manufacturing is achieved, the alloy has better strong plasticity after additive manufacturing forming and heat treatment, selection is provided for deep sea equipment, after additive manufacturing is applied, the structure of the deep sea equipment can be optimized, the weight can be reduced, and the service life of the deep sea equipment can be prolonged. The comprehensive performance of equipment is improved.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy material technology, specifically relating to a high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment. Background Technology

[0002] Titanium alloys, due to their near-non-corrosion properties in seawater, significantly reduce the maintenance and upkeep of ship equipment in seawater, earning them the title of "marine metal." Furthermore, their excellent high specific strength makes them widely used as structural components. With the development of the national strategy to build a maritime power, new equipment designed for extreme environments such as the deep sea is rapidly evolving, creating new demands for higher-performance materials and structures suitable for deep-sea applications.

[0003] Additive manufacturing technology is a near-net-shape manufacturing method that builds up components from scratch. Unlike traditional subtractive manufacturing, which involves preparing blanks and then removing excess material through machining, additive manufacturing only fills the required areas. It can easily produce structures that are difficult or impossible to manufacture in traditional machining due to spatial interference. Therefore, additive manufacturing technology has important value for weight reduction and optimization of structural components. In aerospace and other fields, additively manufactured titanium alloy components have begun to be promoted and used.

[0004] However, the materials currently used in additive manufacturing of titanium alloys are all traditional materials used in subtractive manufacturing. As a complex two-phase metallic material, titanium alloys, unlike steel, cannot have their microstructure and properties significantly adjusted through heat treatment. Instead, they require extensive plastic deformation, crushing, and melting to form a solidified structure, followed by heat treatment to finely adjust the microstructure. In essence, the properties of traditional titanium alloys are determined by both deformation and heat treatment. However, additively manufactured titanium alloy components lack this deformation process, and the extraordinary metallurgical processes and cyclic heating involved in their forming process differ significantly from those of traditional titanium alloys. Therefore, developing novel titanium alloy materials tailored to the specific characteristics of additive manufacturing is a crucial direction for research and engineering both domestically and internationally.

[0005] Analysis of existing technologies reveals that the titanium alloys currently used in marine engineering equipment are mostly high-strength Ti-6Al-4V (TC4) and Ti-6Al-3Nb-2Zr-1Mo (Ti-80) alloys with a tensile strength of 800MPa. TC4 alloy, due to its long development history and mature preparation and application technologies, is widely used in aerospace structural components and can also be used in high-temperature service environments below 400℃. Its tensile strength R... m ≥895MPa, yield strength R p0.2≥825MPa. To meet the toughness requirements of marine engineering equipment, it is usually necessary to reduce the interstitial element content of TC4 to improve toughness, but this will result in a slight decrease in its strength (R). p0.2 ≥795MPa). Ti80 alloy is a special titanium alloy developed in my country for ships and deep-sea submersibles, with a tensile strength R... m ≥880MPa, yield strength R p0.2 With a tensile strength ≥800MPa and an impact energy KV2 ≥55J, this alloy exhibits good toughness under medium-to-high strength conditions. The invention patent CN114592142A, entitled "A Medium-Strength, High-Toughness Titanium Alloy with a Yield Strength of 800MPa for Marine Engineering and its Preparation Process," discloses a tensile strength R... m ≥880MPa, yield strength R p0.2 ≥800MPa, impact energy KV2≥70J, fracture toughness K IC ≥100MPa·m 1 / 2 This invention discloses a high-strength and high-toughness titanium alloy for marine engineering. While possessing excellent impact resistance and fracture toughness, its strength is relatively low. Patent CN107541615A, entitled "A High-Strength and High-Toughness Titanium Alloy for Marine Engineering," discloses a tensile strength R... m ≥850MPa, yield strength R p0.2 ≥750MPa, impact toughness α KV2 ≥30J / cm 2 Titanium alloys for marine engineering possess good impact resistance but relatively low strength. These alloys also exhibit low strength-to-ductility levels, making it difficult to meet the ever-increasing performance requirements.

[0006] At a higher strength level, the invention patent CN106498231B, entitled "A Titanium Alloy for Marine Engineering with a Yield Strength Higher Than 1000MPa," discloses a tensile strength R... m ≥1200MPa, yield strength R p0.2 This titanium alloy for marine engineering has a strength and ductility of ≥1000MPa and an elongation A≥12.0%. However, for titanium alloys designed for traditional subtractive manufacturing, the high Mo equivalent after forming using additive manufacturing technology severely limits the heat treatment space, resulting in a significant reduction in the alloy's ductility.

[0007] Therefore, in response to the dual demands on materials and structures posed by the ever-evolving deep-sea equipment, it is necessary to develop high-strength and high-toughness titanium alloys for additive manufacturing of deep-sea equipment that incorporate additive manufacturing characteristics. Summary of the Invention

[0008] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment. This titanium alloy is produced by adding Al, Mo, V, Cr, Zr, and Nb elements and controlling their content, as well as by controlling the d-electron concentration parameters B0 and M of the titanium alloy. d By rationally combining different alloys, the microstructure and properties of the alloys after additive manufacturing can be effectively controlled, ensuring that the mechanical properties after additive manufacturing and heat treatment reach the tensile strength R. m ≥1100MPa, yield strength R p0.2 With a strength of ≥1050MPa and an elongation of A≥9%, it can meet the application requirements of complex components in additive manufacturing of deep-sea equipment.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment, characterized in that the high-strength and high-toughness titanium alloy is composed of the following components by mass percentage: Al 4.8%~5.5%, Mo 2.8%~3.2%, V 2.5%~3.5%, Cr 2.8%~3.2%, Zr 1.5%~2.5%, Nb 0.8%~1.2%, with the balance being Ti and unavoidable impurity elements; the d-electron concentration parameter B0 of the high-strength and high-toughness titanium alloy satisfies 0.765≤B0≤0.767, and the parameter M d Satisfying 2.374≤M d ≤2.385; the tensile strength R of the high-strength and high-toughness titanium alloy after additive manufacturing and solution treatment and aging. m ≥1100MPa, yield strength R p0.2 ≥1050MPa, elongation A≥9%.

[0010] The specific process of solution treatment and aging treatment in this invention is as follows: first, the solution is kept at 800°C for 1.5 hours and then air-cooled; then, the solution is kept at 580°C for 6 hours and then air-cooled.

[0011] The preparation process of the high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment in this invention is the conventional preparation process of additive manufacturing titanium alloy materials: First, sponge titanium, aluminum briquettes, AlMo master alloy, AlV master alloy, metallic chromium, sponge zirconium, and AlNb master alloy are mixed according to the designed composition ratio and pressed into electrodes. Then, the electrodes are melted three times in a vacuum arc furnace to obtain ingots. After that, the ingots are drawn directly at 950℃~1150℃ to form electrode rods for preparing titanium alloy powder. After the powder is prepared, it is then formed by additive manufacturing.

[0012] The aforementioned high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment is characterized in that the high-strength and high-toughness titanium alloy is composed of the following components by mass percentage: Al 4.8%, Mo 2.8%, V 2.5%, Cr 2.8%, Zr 1.5%, Nb 0.8%, with the balance being Ti and unavoidable impurities.

[0013] The aforementioned high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment is characterized in that the high-strength and high-toughness titanium alloy is composed of the following components by mass percentage: Al 5.0%, Mo 3.0%, V 3.0%, Cr 3.0%, Zr 2.0%, Nb 1.0%, with the balance being Ti and unavoidable impurities.

[0014] The aforementioned high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment is characterized in that the high-strength and high-toughness titanium alloy is composed of the following components by mass percentage: Al 5.5%, Mo 3.2%, V 3.5%, Cr 3.2%, Zr 2.5%, Nb 1.2%, with the balance being Ti and unavoidable impurities.

[0015] Compared with the prior art, the present invention has the following advantages: 1. This invention involves adding 4.8%~5.5% Al, 2.8%~3.2% Mo, 2.5%~3.5% V, 2.8%~3.2% Cr, 1.5%~2.5% Zr, and 0.8%~1.2% Nb by mass percentage to titanium, with the balance being Ti and unavoidable impurity elements, to form a Ti-Al-Mo-V-Cr-Zr-Nb titanium alloy. When selecting the composition, the d-electron concentration parameters B0 and M of the titanium alloy are considered. d The values ​​are controlled at 0.765≤B0≤0.767 and 2.374≤M, respectively. d With a value of ≤2.385, the heat treatment window after additive manufacturing is effectively controlled, thereby achieving effective control over the microstructure and property regulation window after alloy additive manufacturing.

[0016] 2. The titanium alloy of the present invention contains a low proportion of β-stabilizing elements Mo, V, Cr and Nb, which controls the alloy within the range of α+β dual-phase titanium alloy. The deposited microstructure after additive manufacturing can be effectively controlled to transform into short rod-shaped α phases dispersed on the β matrix. This microstructure can be fully spheroidized by heat treatment, thereby improving the plasticity of the titanium alloy.

[0017] 3. By adding an appropriate amount of neutral element Zr to the titanium alloy of the present invention, the crystal lattice can be coordinated and twinning deformation can be promoted, providing a suitable space for the lattice distortion between the micro-regions after solidification in the additive manufacturing process of extraordinary metallurgy, thereby reducing the damage caused by internal stress in the titanium alloy during the forming process and thus improving the plasticity of the titanium alloy.

[0018] 4. The titanium alloy of the present invention achieves excellent strength and plasticity after solution treatment and aging after additive manufacturing. The tensile strength R of this high-strength and high-toughness titanium alloy for additive manufacturing is... m ≥1100MPa, yield strength R p0.2 ≥1050MPa, elongation A≥9%; Currently, the marine engineering titanium alloy materials with performance exceeding this standard are all alloys developed for traditional subtractive manufacturing processes, and cannot achieve this performance level after heat treatment in the solidified state.

[0019] 5. Compared with the currently used marine engineering titanium alloys TC4 and Ti-80, as well as other publicly disclosed alloys mentioned above, the high-strength and high-toughness titanium alloy of this invention has higher strength and better plasticity. When designing the structure of deep-sea equipment, it can effectively reduce the structural parameters of wall thickness and reduce the structural weight. At the same time, additive manufacturing technology can be used to optimize the topology of the existing structure. The optimized structure can continuously reduce the structural weight while maintaining the original load requirements, thereby significantly improving the overall performance level of the new deep-sea equipment and reducing material costs and shortening the manufacturing cycle.

[0020] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0021] Example 1 The high-strength and high-toughness titanium alloy of this embodiment is composed of the following components by mass percentage: Al 4.8%, Mo 2.8%, V 2.5%, Cr 2.8%, Zr 1.5%, Nb 0.8%, with the balance being Ti and unavoidable impurity elements; the d-electron concentration parameter B0 of the high-strength and high-toughness titanium alloy is 0.767, and the parameter M... d =2.385.

[0022] The high-strength and high-toughness titanium alloy of this embodiment is prepared through the following process: First, sponge titanium, aluminum briquettes, AlMo master alloy, AlV master alloy, metallic chromium, sponge zirconium, and AlNb master alloy are mixed according to the designed composition ratio and pressed into electrodes. The electrodes are then melted three times in a vacuum arc furnace to obtain an ingot with a diameter of 160 mm. The melted ingot is then drawn into a blank bar with a diameter of 100 mm at 1150 °C. The blank bar is then forged into a bar with a diameter of 55 mm using a radial forging machine. The bar is then machined into an electrode bar according to the dimensions of the powder electrode bar. The electrode bar is then processed into alloy spherical powder using a powder preparation device. The powder is sieved to the required particle size and then printed into material using additive manufacturing equipment. The material is then held at 800 °C for 1.5 h and air-cooled, and then held at 580 °C for 6 h and air-cooled again to obtain the high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment.

[0023] Example 2 The high-strength and high-toughness titanium alloy of this embodiment is composed of the following components by mass percentage: Al 5.0%, Mo 3.0%, V 3.0%, Cr 3.0%, Zr 2.0%, Nb 1.0%, with the balance being Ti and unavoidable impurity elements; the d-electron concentration parameter B0 of the high-strength and high-toughness titanium alloy is 0.767, and the parameter M... d =2.380.

[0024] The high-strength and high-toughness titanium alloy of this embodiment is prepared through the following process: First, sponge titanium, aluminum briquettes, AlMo master alloy, AlV master alloy, metallic chromium, sponge zirconium, and AlNb master alloy are mixed according to the designed composition ratio and pressed into electrodes. The electrodes are then melted three times in a vacuum arc furnace to obtain an ingot with a diameter of 160 mm. The melted ingot is then drawn into a blank bar with a diameter of 100 mm at 1150 °C. The blank bar is then forged into a bar with a diameter of 55 mm using a radial forging machine. The bar is then machined into an electrode bar according to the dimensions of the powder electrode bar. The electrode bar is then processed into alloy spherical powder using a powder preparation device. The powder is sieved to the required particle size and then printed into material using additive manufacturing equipment. The material is then held at 800 °C for 1.5 h and air-cooled, and then held at 580 °C for 6 h and air-cooled again to obtain the high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment.

[0025] Example 3 The high-strength and high-toughness titanium alloy of this embodiment is composed of the following components by mass percentage: Al 5.5%, Mo 3.2%, V 3.5%, Cr 3.2%, Zr 2.5%, Nb 1.2%, with the balance being Ti and unavoidable impurity elements; the d-electron concentration parameter B0 of the high-strength and high-toughness titanium alloy is 0.765, and the parameter M... d =2.374.

[0026] The high-strength and high-toughness titanium alloy of this embodiment is prepared through the following process: First, sponge titanium, aluminum briquettes, AlMo master alloy, AlV master alloy, metallic chromium, sponge zirconium, and AlNb master alloy are mixed according to the designed composition ratio and pressed into electrodes. The electrodes are then melted three times in a vacuum arc furnace to obtain an ingot with a diameter of 160 mm. The melted ingot is then drawn into a blank bar with a diameter of 100 mm at 1150 °C. The blank bar is then forged into a bar with a diameter of 55 mm using a radial forging machine. The bar is then machined into an electrode bar according to the dimensions of the powder electrode bar. The electrode bar is then processed into alloy spherical powder using a powder preparation device. The powder is sieved to the required particle size and then printed into material using additive manufacturing equipment. The material is then held at 800 °C for 1.5 h and air-cooled, and then held at 580 °C for 6 h and air-cooled again to obtain the high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment.

[0027] The high-strength and high-toughness titanium alloys for additive manufacturing of deep-sea equipment prepared in Examples 1 to 3 of this invention were sampled and their room temperature tensile properties were tested. The test results are shown in Table 1.

[0028] Table 1

[0029] As can be seen from Table 1, the high-strength and high-toughness titanium alloys for additive manufacturing of deep-sea equipment prepared in Examples 1 to 3 of the present invention have excellent strength and plasticity properties.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment, characterized in that, This high-strength and high-toughness titanium alloy is composed of the following components by mass percentage. Composition: Al 4.8%~5.5%, Mo 2.8%~3.2%, V 2.5%~3.5%, Cr 2.8%~3.2%, Zr 1.5%~2.5%, Nb 0.8%~1.2%, with the balance being Ti and unavoidable impurity elements; the d-electron concentration parameter B0 of the high-strength and high-toughness titanium alloy satisfies 0.765≤B0≤0.767, and the parameter M... d Satisfying 2.374≤M d ≤2.385; the tensile strength R of the high-strength and high-toughness titanium alloy after additive manufacturing and solution treatment and aging. m ≥1100MPa, yield strength R p0.2 ≥1050MPa, elongation A≥9%.

2. The high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment according to claim 1, characterized in that, The high-strength and high-toughness titanium alloy is composed of the following components by mass percentage. Composition: Al 4.8%, Mo 2.8%, V 2.5%, Cr 2.8%, Zr 1.5%, Nb 0.8%, balance Ti and unavoidable impurities.

3. The high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment according to claim 1, characterized in that, The high-strength and high-toughness titanium alloy is composed of the following components by mass percentage. Composition: Al 5.0%, Mo 3.0%, V 3.0%, Cr 3.0%, Zr 2.0%, Nb 1.0%, balance Ti and unavoidable impurities.

4. The high-strength and high-toughness titanium alloy for additive manufacturing of deep-sea equipment according to claim 1, characterized in that, The high-strength and high-toughness titanium alloy is composed of the following components by mass percentage. Composition: Al 5.5%, Mo 3.2%, V 3.5%, Cr 3.2%, Zr 2.5%, Nb 1.2%, balance Ti and unavoidable impurities.

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