A method for improving the forming of a base body of a titanium alloy rod containing Nb, Ti and Al

Abstract

This invention belongs to the field of alloy processing technology, specifically relating to a method for forming titanium alloy bars with increased Nb, Ti, and Al content in the matrix. The method involves melting an ingot, controlling the following components: P ≤ 0.015%, S ≤ 0.015%, Si ≤ 0.2%, Mn ≤ 0.2%, 5.2% ≤ Nb + Ta ≤ 5.5%, and 1.5% ≤ Ti + Al ≤ 1.8%. After forging, the ingot is heat-treated at an initial temperature ≤ 500℃, then heated to 580–620℃. The ingot is then machined, with roughing speeds of 50–60 r / min and finishing speeds of 60–80 r / min. Finally, a shot-strengthening treatment is performed to obtain the titanium alloy bar. This invention, based on the control of impurity elements and compositional segregation during the melting process, coupled with stress-relieving heat treatment after forging, low-stress cutting, and surface strengthening treatment, achieves tensile strength and yield strength that are more than 100 MPa higher than conventional standards.

Description

Technical Field

[0001] This invention belongs to the field of alloy processing technology, specifically relating to a method for forming titanium alloy rods with increased Nb, Ti and Al content in the matrix. Background Technology

[0002] This high-temperature alloy, containing Nb, Ti, and Al in its matrix and exhibiting γ” and γ' phases, is a nickel-based high-temperature alloy. Its core chemical composition, by mass percentage, is as follows: Ni (nickel) 50.0%–55.0%, Cr (chromium) 17.0%–21.0%, Fe (iron) balance, Nb+Ta (niobium+tantalum) 4.75%–5.50%; strengthening and auxiliary elements: Mo (molybdenum) 2.80%–3.30% (solid solution strengthening), Ti (titanium) 0.65%–1.15%. Al (aluminum) 0.20%~0.80% (precipitation strengthening, forming γ” phase in synergy with Ti); impurity control: C≤0.08, Mn≤0.35, Si≤0.35, P≤0.015, S≤0.015, B≤0.006, Cu≤0.30. The core of its composition design is to form γ” (Ni3Nb) and γ’ (Ni3(Al,Ti)) phases by combining the matrix with Nb / Ti / Al to achieve high-temperature strengthening, while taking into account corrosion resistance and processability.

[0003] This nickel-based superalloy is used in high-pressure compressor blades and turbine disks for aero-engines; rocket engine thrust chambers and spacecraft structural components in spacecraft; energy and power, nuclear power, gas turbines, and thermal power; drill pipes, blowout preventers, and underwater connectors for deep-sea drilling platforms in marine engineering; turbine components and propeller shafts for marine gas turbines in marine propulsion; precision machinery rotors and core components for high-speed centrifuges in high-end equipment manufacturing; turbocharger impellers and exhaust system components for racing engines in the automotive industry; and corrosion-resistant centrifugal pump shafts and reactor agitators in other high-end applications, medical equipment, and chemical equipment.

[0004] Currently, for high-temperature alloy bars containing Nb, Ti, and Al in the matrix and with γ” and γ’ phases, the forming and forging method is usually adopted. That is, the bar is formed by forging and heat treatment according to the required size. Although the basic forming and microstructure control of the bar can be achieved, it is difficult to achieve the tensile strength and yield strength required by the bar that are more than 100 MPa higher than the conventional standard requirements. Summary of the Invention

[0005] The purpose of this invention is to provide a method for forming titanium alloy bars with a matrix containing Nb, Ti, and Al. Based on the control of impurity elements and compositional segregation during the melting process, stress-relieving preheating treatment after forging, low-speed low-stress cutting, and surface strengthening treatment processes are coupled and controlled to make the tensile strength and yield strength of the bars more than 100 MPa higher than the conventional standard requirements, thereby improving the mechanical properties and effectively increasing the yield of qualified bars, reducing scrap, and meeting the stringent performance requirements of the aerospace industry and high-end equipment manufacturing.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] The purpose of this invention is to provide a method for forming titanium alloy bars with a matrix containing Nb, Ti, and Al, including melting, forging, and cutting, comprising the following steps: S1. Melt the titanium alloy bar ingot to form a molten liquid. Control the following percentages by mass: P≤0.015%, S≤0.015%, Si≤0.2%, Mn≤0.2%, 5.2%≤Nb+Ta≤5.5%, 1.5%≤Ti+Al≤1.8%.

[0008] S2. After melting, a forging billet is formed. The forging billet is forged by upsetting and drawing. After forging, it is heat-treated at an initial temperature of ≤500℃ to 580℃~620℃ to obtain a bar billet.

[0009] S3. The billet is cut using a combination of roughing and finishing turning. The roughing speed is 50 r / min to 60 r / min and the feed rate is 0.2 mm / r to 0.25 mm / r. The finishing speed is 60 r / min to 80 r / min and the feed rate is 0.15 mm / r to 0.2 mm / r, thus obtaining the cut bar.

[0010] S4. The cut bar is subjected to surface shot peening to obtain titanium alloy bar.

[0011] Furthermore, the Mo content in the molten liquid is controlled to be 3.0% to 3.3% by mass percentage.

[0012] Furthermore, the heat treatment holding time is 2h to 2.5h, and the cooling method is air cooling.

[0013] Furthermore, during the roughing process, the depth of cut is 2.0 mm / cut to 2.5 mm / cut.

[0014] Furthermore, during the finishing process, the depth of cut is 0.5mm / cut to 1.0mm / cut.

[0015] Furthermore, during the shot peening process, the shot diameter is 0.2mm to 0.6mm, the shot pressure is 0.4MPa to 0.8MPa, and the coverage is 100%.

[0016] Furthermore, before shot peening, the cut bar stock is heat-treated by holding it at 700℃~750℃ for 6h~8h, and then cooling it down to 600℃~640℃ at 40℃ / h~50℃ / h and holding it for 6h~8h. The cooling method is air cooling.

[0017] Furthermore, forging includes a billet forging process and a hot forging forming process. In the billet forging process, the forging temperature is 1120℃~1150℃, the final forging temperature is ≥960℃, and the deformation per forging is 25%~40%. In the hot forging forming process, the forging temperature is 1080℃~1120℃, and the final forging temperature is ≥930℃.

[0018] Furthermore, the smelting process employs vacuum induction melting and vacuum arc remelting. In vacuum induction melting, the vacuum level is <5 Pa during the melting period and <1 Pa during the refining period. In vacuum arc remelting, the vacuum level is ≤5 × 10⁻⁶ Pa. -2 Pa.

[0019] Compared with the prior art, the present invention has the following advantages: The forming method provided by this invention is based on the control of impurity elements and component segregation during the melting process. Precise control of P and S elements effectively avoids the decrease in room temperature plasticity caused by P segregation, improves the hot plasticity of the alloy, ensures the impact toughness of the material, and reduces the generation of cracks during forging and forming. Precise control of Si and Mn elements prevents the formation of oxide impurities. By optimizing the Nb+Ta and Ti+Al contents to increase the content of γ"(Ni3Nb) and γ'(Ni3(Al,Ti)) phases, and further stress heat treatment after forging, strength fluctuations caused by residual stress are avoided, ensuring that the billet achieves homogeneity. The material's internal structure is optimized by reducing the surface work-hardened layer and microcracks through low-speed, low-stress cutting and forming a residual compressive stress layer through shot peening, which inhibits crack propagation and improves the uniformity of the internal structure. By controlling the segregation of impurity elements and components during the smelting process, performing stress-relief preheating after forging, and coupling the low-speed, low-stress cutting and surface strengthening processes, the tensile strength and yield strength required by the material are increased by more than 100 MPa compared to the conventional standard requirements. This achieves the goal of improving mechanical properties, effectively increasing the yield rate of the material, reducing scrap, and meeting the stringent performance requirements of the aerospace industry and high-end equipment manufacturing. Attached Figure Description

[0020] Figure 1 This is a high-magnification microstructure inspection image of the titanium alloy bar forging of Embodiment 1 of the present invention.

[0021] Figure 2 This is a high-magnification microstructure inspection image of the titanium alloy bar forging of Embodiment 2 of the present invention. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0024] Currently, for high-temperature alloys with a matrix containing Nb, Ti, and Al and γ” and γ' phases, forging and heat treatment are usually sufficient to produce the required bars, but this cannot meet the demand for tensile strength and yield strength that are more than 100 MPa higher than the conventional standards. Therefore, ensuring reasonable control throughout the entire process from the melting of the original titanium ingot to the final bar forming, and ensuring that the mechanical properties of the bars meet the high-strength standards after forging and heat treatment, is crucial for this product.

[0025] This invention, based on research into the coupled control of the entire process from smelting and forging to heat treatment, establishes a set of process windows and control methods capable of stably achieving high-strength performance targets. Its core involves optimizing raw material impurities and compositional segregation, optimizing machining processes, and optimizing surface treatment processes for the aforementioned high-temperature alloys containing Nb, Ti, and Al in the matrix and exhibiting γ” and γ' phases, to achieve the high-strength mechanical properties of these materials. Specifically:

[0026] A method for forming titanium alloy bars with improved matrix content of Nb, Ti, and Al, comprising melting, forging, and cutting, including the following steps: S1. Titanium alloy bar ingots are smelted using VIM+VAR dual melting to precisely control the alloy composition, reduce the concentration of impurity gases, and form a molten liquid. The molten liquid is then used to control impurities and component segregation. First, phosphorus (P) and sulfur (S) are precisely controlled by mass percentage. P poses a risk of grain boundary embrittlement, while S increases the risk of hot working cracks. By controlling P ≤ 0.015% and S ≤ 0.015% in the molten liquid, the decrease in room temperature plasticity due to P segregation is effectively avoided, improving the alloy's hot plasticity, ensuring the material's impact toughness, and reducing edge cracking and surface cracking during forging and forming. When sponge titanium is present in the ingot, the final original elemental content of the sponge titanium is controlled: its composition is P ≤ 0.01% and S ≤ 0.01%. Secondly, the Si and Mn elements were precisely controlled by mass percentage. By controlling Si ≤ 0.2% and Mn ≤ 0.2% in the molten metal, the formation of oxide impurities was prevented. The synthesis ratio of alloying elements in the original materials was precisely optimized. Within the standard range, the maximum upper limit of Nb+Ta content was increased to 5.2%–5.5%, and Ti+Al content was controlled at 1.5%–1.8% to increase the content of γ(Ni3Nb) and γ'(Ni3(Al,Ti)) phases. Within the standard range, Mo was further adjusted. The upper limit of the content is 3.0% to 3.3% to maximize the effect of solid solution strengthening. It is understood that this invention controls the phosphorus element by controlling the composition of the ingot (i.e., source batching control) and supplementing it with external dephosphorization; controls the sulfur element through VIM+VAR duplex melting desulfurization; and controls the silicon and mn elements by controlling the composition of the ingot (i.e., source batching control), or by adding alloys of these elements to the molten metal for adjustment, thereby ensuring that the final composition falls within the required range.

[0027] S2. After melting, the billet is cast into a forging billet. The forging billet is then forged, including the initial forging process and the hot forging process. In the initial forging process, upsetting and drawing are used. The forging temperature is 1120℃~1150℃, the final forging temperature is ≥960℃, and the deformation per forging is 25%~40%. In the hot forging process, the forging temperature is 1080℃~1120℃, the final forging temperature is ≥930℃, and an intermediate billet is obtained. It should be noted that the final forging temperature must be strictly controlled to ≥900℃ to avoid precipitation of brittle δ phase, which would lead to performance deterioration.

[0028] S3. To improve the tensile strength and yield strength of the above-mentioned bars, stress pretreatment is performed immediately after forging. The bars are placed in the furnace at an initial temperature of ≤500℃ and then heated to 580℃~620℃. After holding at this temperature for 2h~2.5h, the bars are removed from the furnace and air-cooled to avoid strength fluctuations caused by residual stress, thus obtaining the bar billet.

[0029] S4. The billet undergoes cold working, i.e., machining. Low-speed, low-stress cutting is used to reduce the surface work-hardened layer and micro-cracks. The billet is cut using a combination of roughing and finishing. The cutting speed for roughing is 50 r / min to 60 r / min, the feed rate is 0.2 mm / r to 0.25 mm / r, and the depth of cut is 2.0 mm / cut to 2.5 mm / cut. The cutting speed for finishing is 60 r / min to 80 r / min, the feed rate is 0.15 mm / r to 0.2 mm / r, and the depth of cut is 0.5 mm / cut to 1.0 mm / cut, resulting in the cut bar stock.

[0030] S5. Perform conventional heat treatment on the cut bar stock. The heat treatment method is to hold at 700℃~750℃ for 6h~8h, then reduce the temperature at 40℃ / h~50℃ / h and hold at 600℃~640℃ for 6h~8h. The cooling method is air cooling. Then, perform subsequent surface shot peening strengthening treatment. Surface shot peening strengthening treatment can also be performed on key components. The diameter of the shot is 0.2mm~0.6mm, and the material of the shot is structural steel of 40HRC~50HRC or high-strength steel of ≤55HRC. During the shot peening strengthening treatment, the shot pressure is 0.4MPa~0.8MPa, the speed is 60m / s~70m / s, the time is 1min~5min, the distance between the shot and the surface is 120mm~170mm, the coverage is 100%, and the surface roughness RA is 1.6μm~6.3μm. A residual compressive stress layer is formed on the surface, which inhibits crack propagation and improves the surface strength by about 5%~15%, resulting in titanium alloy bar stock.

[0031] It is understandable that the parameters not mentioned above involved in the smelting, forging, and machining processes of ingots are all conventional methods. The purpose of this invention is to achieve the desired tensile strength and yield strength of bars by more than 100 MPa higher than the conventional standard requirements through quantitative control methods of raw material impurity and component segregation, optimized machining processes, and optimized surface treatment processes. Based on the control of impurity elements and component segregation during the smelting process, stress-relieving preheating treatment after forging, low-speed low-stress cutting, and surface strengthening treatment processes coupled with control methods, the tensile strength and yield strength required by the bars are increased by more than 100 MPa. This achieves the goal of improving mechanical properties and effectively increases the yield of qualified bars, reducing scrap.

[0032] The following specific examples will provide further explanation.

[0033] Example 1 A method for forming titanium alloy bars with improved Nb, Ti, and Al matrix, wherein: forming specifications: Φ200mm×2500mm; category: II; weight: 661.3Kg; name: Φ200mm bars; quantity: 2 pieces; ingot section number: 1-1, 1-2; bar standard: Q / S10-0313-2004. The ingot is subjected to melting, forging, cutting, and heat treatment in sequence, including the following steps:

[0034] Step 1: Vacuum induction melting (VIM) combined with vacuum arc remelting (VAR) is performed on the elemental ingots to precisely control the alloy composition and reduce the concentration of impurity gases. The vacuum level for VIM melting is: melting period <5 Pa; refining period <1 Pa, refining temperature 1500℃, time 1 hour. Through the synergistic control of VIM and VAR technologies, the contents of P ≤0.010%, S ≤0.0015%, Si ≤0.030%, Mn ≤0.030%, Nb+Ta 5.2%~5.5%, Ti+Al 5.25%~5.55%, and Mo 3.0%~3.35% in the molten liquid are controlled.

[0035] Step 2: After casting to form a forging billet, forging is carried out. The forging process is upsetting and drawing, with a forging temperature of 1130℃±10℃ and a final forging temperature of ≥960℃. The deformation per forging is 35%. In the hot forging process, the forging temperature is 1100℃±10℃ and the final forging temperature is ≥930℃, resulting in an intermediate billet.

[0036] Step 3: After forging, the intermediate billet is immediately subjected to stress-relieving heat treatment. It is placed in the furnace at an initial temperature of ≤500℃ and heated to 595℃±8℃ with the furnace. After holding at this temperature for 2.3 hours, it is taken out of the furnace and air-cooled.

[0037] Step 4: Perform machining processes using low-speed, low-stress cutting, including: The roughing cutting speed is 55 r / min, the feed rate is 0.23 mm / r, and the depth of cut is 2.3 mm / cut; the finishing cutting speed is 65 r / min, the feed rate is 0.18 mm / r, and the depth of cut is 0.6 mm / cut, thus obtaining the cut bar stock.

[0038] Step 5: Heat-treat the cut bar stock by holding it at 720℃ for 8 hours, then reducing the temperature at 50℃ / h to 620℃ and holding it at that temperature for 8 hours, followed by air cooling. Then, perform subsequent surface shot peening strengthening treatment. The shot diameter is 0.3mm, the shot material is 50HRC structural steel, the coverage is 100%, the shot pressure is 0.6MPa, the shot velocity is 65m / s, the time is 3min, the shot-to-surface distance is 140mm, and the surface roughness RA after shot peening is 4.5μm, increasing the surface strength by approximately 10%.

[0039] The required production process technical parameters can be controlled according to steps 1 to 5 above; the remaining molding and heat treatment can be completed step by step according to the requirements of each process.

[0040] Step 6: After forging, sandblasting and grinding are performed to check if the dimensions meet the requirements of the forging.

[0041] Step 7, physicochemical testing.

[0042] Step 8: Final inspection and warehousing.

[0043] The performance of the titanium alloy rods prepared in Example 1 was tested, and the results are shown in Tables 1 to 3.

[0044] Table 1. Room temperature mechanical properties (transverse) of titanium alloy bars Table 2. High-temperature (600℃ for 15 min) mechanical properties of titanium alloy bars (transverse direction) Table 3. Test results of titanium alloy bars As shown in Tables 1 to 3, the titanium alloy bar forgings prepared in Example 1 meet the requirements for both tensile strength and yield strength. The tensile strength is more than 200 MPa higher than the standard requirement, and the yield strength Rp0.2 is nearly 200 MPa higher than the standard requirement, which is highly satisfactory. All other properties are qualified and meet the standard requirements for bars.

[0045] The titanium alloy bar forgings prepared in Example 1 were subjected to low-magnification and high-magnification microstructure inspections. The low-magnification microstructure showed no cracks, folds, porosity, metallic or non-metallic inclusions, or other visible metallurgical defects at either end. No clearly visible grains were observed at low magnification, and the low-magnification microstructure met the standard. Figure 1 Level 2.

[0046] Figure 1 This is a high-magnification microstructure inspection image of the titanium alloy bar forging from Embodiment 1 of the present invention. Figure 1 As shown, the high-magnification structure is a structure produced by processing in both the α-β two-phase regions at both ends, without complete original β grain boundaries, and is an equiaxed α structure on a transformed β matrix.

[0047] Example 2 A method for forming titanium alloy bars with improved Nb, Ti, and Al matrix, wherein: forming specifications: Φ150mm×3000mm; category: II; weight: 446.38Kg; name: Φ150mm bars; quantity: 4 pieces; ingot section numbers: K-1, K-2, K-3, K-4; bar standard: Q / S10-0313-2004. The ingots are sequentially smelted, forged, machined, and heat-treated, including the following steps:

[0048] Step 1: Vacuum induction melting (VIM) combined with vacuum arc remelting (VAR) is performed on the elemental ingots to precisely control the alloy composition and reduce the concentration of impurity gases. The vacuum level for VIM melting is: melting period <5 Pa; refining period <1 Pa, refining temperature 1500℃, time 1 hour. Through the synergistic control of VIM and VAR technologies, the contents of P ≤0.013%, S ≤0.0017%, Si ≤0.033%, Mn ≤0.028%, Nb+Ta 5.2%~5.5%, Ti+Al 5.35%~5.40%, and Mo 3.10%~3.25% in the molten liquid.

[0049] Step 2: After casting to form a forging billet, forging is carried out. The forging process is upsetting and drawing, with a forging temperature of 1130℃±10℃ and a final forging temperature of ≥960℃. The deformation per forging is 35%. In the hot forging process, the forging temperature is 1100℃±10℃ and the final forging temperature is ≥930℃, resulting in an intermediate billet.

[0050] Step 3: After forging, the intermediate billet is immediately subjected to stress-relieving heat treatment. It is placed in the furnace at an initial temperature of ≤500℃ and heated to 595℃±8℃ with the furnace. After holding at this temperature for 2.0h, it is taken out of the furnace and air-cooled.

[0051] Step 4: Perform machining processes using low-speed, low-stress cutting, including: The roughing cutting speed is 55 r / min, the feed rate is 0.23 mm / r, and the depth of cut is 2.3 mm / cut; the finishing cutting speed is 65 r / min, the feed rate is 0.18 mm / r, and the depth of cut is 0.6 mm / cut, thus obtaining the cut bar stock.

[0052] Step 5: Heat-treat the cut bar stock by holding it at 720℃ for 6 hours, then reducing the temperature at 45℃ / h to 620℃ and holding it for 6 hours, followed by air cooling. Then, perform subsequent surface shot peening strengthening treatment. The shot diameter is 0.3mm, the shot material is 50HRC structural steel, the coverage is 100%, the shot pressure is 0.6MPa, the velocity is 65m / s, the time is 3min, the distance between the shot and the surface is 140mm, and the surface roughness RA after shot peening is 4.5μm, increasing the surface strength by about 10%.

[0053] The required production process technical parameters can be controlled according to steps 1 to 5 above; the remaining molding and heat treatment can be completed step by step according to the requirements of each process.

[0054] Step 6: After forging, sandblasting and grinding are performed to check if the dimensions meet the requirements of the forging.

[0055] Step 7, physicochemical testing.

[0056] Step 8: Final inspection and warehousing.

[0057] The properties of the titanium alloy rods prepared in Example 2 were tested, and the results are shown in Tables 4 to 6.

[0058] Table 4. Room temperature mechanical properties (transverse) of titanium alloy bars Table 5. High-temperature (600℃ for 15 min) mechanical properties of titanium alloy bars (transverse direction) Table 6. Test results of titanium alloy bars As shown in Tables 4 to 6, the titanium alloy bar forgings prepared in Example 2 meet the requirements for both tensile strength and yield strength. The tensile strength is more than 200 MPa higher than the standard, and the yield strength Rp0.2 is nearly 200 MPa higher than the standard, which is highly satisfactory. All other properties are qualified and meet the standard requirements for bars.

[0059] The titanium alloy bar forgings prepared in Example 2 were subjected to low-magnification and high-magnification microstructure inspections. The low-magnification microstructure showed no cracks, folds, porosity, metallic or non-metallic inclusions, or other metallurgical defects visible to the naked eye at either end. No clearly visible grains were observed at low magnification, and the low-magnification microstructure met the standard. Figure 1 Level 2.

[0060] Figure 2 This is a high-magnification microstructure inspection image of the titanium alloy bar forging from Embodiment 1 of the present invention. Figure 2 As shown, the high-magnification structure is a structure produced by processing in both the α-β two-phase regions at both ends, without complete original β grain boundaries, and is an equiaxed α structure on a transformed β matrix.

[0061] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0062] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for forming titanium alloy bars with a matrix containing Nb, Ti, and Al, comprising melting, forging, and cutting, characterized in that, Includes the following steps: Titanium alloy bar ingots are smelted to form a molten liquid. The molten liquid is controlled by mass percentage as follows: P≤0.015%, S≤0.015%, Si≤0.2%, Mn≤0.2%, 5.2%≤Nb+Ta≤5.5%, and 1.5%≤Ti+Al≤1.8%. After melting, a forging billet is formed. The forging billet is forged by upsetting and drawing. After forging, it is heat-treated at an initial temperature of ≤500℃ to 580℃~620℃ to obtain a bar billet. The billet is cut using a combination of roughing and finishing turning. The roughing turning speed is 50 r / min to 60 r / min and the feed rate is 0.2 mm / r to 0.25 mm / r. The finishing turning speed is 60 r / min to 80 r / min and the feed rate is 0.15 mm / r to 0.2 mm / r, resulting in a cut bar. The cut bar stock is subjected to surface shot peening to obtain titanium alloy bar stock.

2. The method for forming titanium alloy rods with a matrix containing Nb, Ti, and Al according to claim 1, characterized in that, The Mo content in the molten metal should be controlled at 3.0% to 3.3% by mass percentage.

3. The method for forming titanium alloy rods with a matrix containing Nb, Ti, and Al according to claim 1, characterized in that, The heat treatment holding time is 2 to 2.5 hours, and the cooling method is air cooling.

4. The method for forming titanium alloy rods with a matrix containing Nb, Ti, and Al according to claim 1, characterized in that, During roughing, the depth of cut is 2.0 mm / cut to 2.5 mm / cut.

5. The method for forming titanium alloy rods with a matrix containing Nb, Ti, and Al according to claim 1, characterized in that, During the finishing process, the depth of cut is 0.5mm / cut to 1.0mm / cut.

6. The method for forming titanium alloy rods with a matrix containing Nb, Ti, and Al according to claim 1, characterized in that, During the shot peening process, the diameter of the shot is 0.2mm to 0.6mm, the pressure of the shot is 0.4MPa to 0.8MPa, and the coverage rate is 100%.

7. The method for forming titanium alloy rods with a matrix containing Nb, Ti, and Al according to claim 1, characterized in that, Before shot peening, the cutting bar stock is heat-treated by holding it at 700℃~750℃ for 6h~8h, and then cooling it at 40℃ / h~50℃ / h to 600℃~640℃ for 6h~8h. The cooling method is air cooling.

8. The method for forming titanium alloy rods with a matrix containing Nb, Ti, and Al according to claim 1, characterized in that, Forging includes a billet forging process and a hot forging forming process. In the billet forging process, the forging temperature is 1120℃~1150℃, the final forging temperature is ≥960℃, and the deformation per forging is 25%~40%. In the hot forging forming process, the forging temperature is 1080℃~1120℃, and the final forging temperature is ≥930℃.

9. The method for forming titanium alloy rods with a matrix containing Nb, Ti, and Al according to claim 1, characterized in that, The smelting process employs vacuum induction melting and vacuum arc remelting. In vacuum induction melting, the vacuum level is <5 Pa during the melting period and <1 Pa during the refining period. In vacuum arc remelting, the vacuum level is ≤5 × 10⁻⁶ Pa. -2 Pa.

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