A short process preparation technology of high-temperature titanium alloy containing nanosilicide and ultrafine crystal

Abstract

The application discloses a short-process preparation process of high-temperature titanium alloy containing nanosilicide and ultrafine grains and belongs to the technical field of titanium alloy, and comprises the following steps: step one, preparation of ingot; step two, breakdown forging; step three, solid solution water quenching; and step four, one-pass isothermal multi-directional forging. The short-process preparation process of high-temperature titanium alloy containing nanosilicide and ultrafine grains can obtain ultrafine grains and stably precipitate nanosilicide in near-alpha high-temperature titanium alloy, so that the strength and plasticity of the titanium alloy are improved.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy technology, and in particular to a short-process preparation technology for high-temperature titanium alloys containing nano-silicides and ultrafine grains. Background Technology

[0002] High-temperature titanium alloys are widely used in aero-engines due to their high room-temperature strength, good high-temperature resistance, and high oxidation and creep resistance, including components such as fan disks, blades, and compressor disks. Most high-temperature titanium alloys are based on typical near-αTi-Al-Sn-Zr alloys. Due to grain refinement, the finer the grain size, the higher the strength and hardness of the alloy. Furthermore, the appropriate addition of silicon (Si) can also effectively strengthen the solid solution.

[0003] In high-temperature titanium alloys, silicon (Si) typically exists in two forms: 1. as a solid solution element in the matrix; 2. as precipitated hard phase silicides. Silicides generally have two structures: S1 type and S2 type. S1 type is (Ti,Zr)5Si3, and S2 type is (Ti,Zr)6Si3. The size of the silicide precipitation affects the alloy's strength and ductility. Uneven precipitation of large-sized silicides can significantly reduce the alloy's ductility and is also detrimental to strength improvement.

[0004] Related studies have shown that grain size, silicide precipitation and growth are closely related to alloy composition and hot working processes. Since titanium alloys have a high stacking fault energy (HCP), strong plastic strain (SPD) can be applied to refine coarse-grained alloys into ultrafine grains to maximize their strength and toughness. Simultaneously, silicides precipitate in high-temperature titanium alloys during the SPD stage, and the size of the precipitated phase is controlled by the deformation temperature. If both ultrafine grains can be formed in the alloy and the size of the precipitated silicide phase can be controlled at the nanoscale, the strength and toughness of the titanium alloy can be improved through the synergistic effect of grain refinement strengthening and precipitation strengthening mechanisms.

[0005] Currently, multi-directional forging is commonly used in domestic and international research reports to refine near-α high-temperature titanium alloys. However, multi-directional forging under low strain conditions can easily cause inhomogeneity in the microstructure. To obtain a uniform ultrafine grain structure, it is necessary to continuously increase the number of deformation passes to apply more shear strain.

[0006] Cooling multi-directional forging can cause the silicides precipitated in the titanium alloy matrix to exhibit micro- and nano-scale characteristics: when forging in the β phase region, micron-sized silicides will precipitate at the grain boundaries. Then, when forging in the high-temperature section of the (α+β) phase region, submicron-sized silicides will precipitate again at the grain boundaries and within the grains. Finally, when forging in the low-temperature section of the (α+β) phase region, nano-sized silicides can precipitate within the grains. At this point, the distribution of silicides in the matrix is ​​uneven, and the size of the silicides gradually decreases from the grain boundaries to the grains, exhibiting micro- and nano-scale characteristics. The silicides formed in this way are not conducive to improving the strength and plasticity of the alloy.

[0007] While theoretically, multi-pass, multi-directional forging in the low-temperature region of the (α+β) phase can precipitate nanoscale silicides and achieve ultrafine grains in the matrix, in actual industrial production, multi-pass forging not only increases time and equipment costs, but also, due to the coarse microstructure of the cast alloy and defects such as shrinkage cavities and porosity, increases the alloy's deformation resistance and reduces its fluidity during low-temperature forging. This makes the material prone to cracking during forging, resulting in poor formability and making it difficult to put into actual production. Therefore, in actual processing, how to achieve ultrafine grain formation and control the size of precipitated silicides at the nanoscale while shortening the processing flow is particularly important for improving the strength and plasticity of titanium alloys. Summary of the Invention

[0008] The purpose of this invention is to provide a short-process preparation process for high-temperature titanium alloys containing nano-silicides and ultrafine grains. This process reduces the number of forging passes and shortens the process flow. It relies solely on a simple solution treatment and quenching heat treatment process and isothermal multi-directional forging technology to enable the near-α high-temperature titanium alloy to form ultrafine grains and precipitate uniform nano-silicides in the alloy, thereby improving the strength and plasticity of the alloy.

[0009] To achieve the above objectives, this invention provides a short-process preparation technology for high-temperature titanium alloys containing nano-silicides and ultrafine grains, comprising the following steps:

[0010] Step 1: Preparing the ingot

[0011] Raw materials are weighed and ingots are prepared by vacuum induction melting.

[0012] Step 2: Forging the billet

[0013] The surface of the forged alloy is coated with an anti-oxidation coating. After it dries completely, it is wrapped with asbestos and placed in a heating furnace to be heated and kept at a certain temperature for a period of time. The forging is carried out in the high-temperature section of the (α+β) phase region.

[0014] Step 3: Solution cooling and quenching

[0015] The forged alloy is placed in a heating furnace and heated to a certain temperature for solution treatment and held at that temperature for a period of time, and then water-cooled and quenched.

[0016] Step 4: One-stage isothermal multi-directional forging

[0017] After the alloy surface is quenched in step three, an anti-oxidation coating is applied. After it dries completely, the alloy is wrapped in asbestos and placed in a heating furnace for one round of isothermal multi-directional forging.

[0018] Preferably, the ingredients in step one are formulated according to the following elemental weight percentages: 5.7-6.5 wt% Al, 2.5-3.5 wt% Sn, 0.8-1.2 wt% Mo, 0.8-1.2 wt% Nb, 0.8-1.2 wt% W, 7.0-9.5 wt% Zr, 0.35-0.53 wt% Si, 0-0.2 wt% C, with the remainder being Ti and other unavoidable impurity elements.

[0019] Preferably, the antioxidant coating used in step two and step four is a Ti1200 antioxidant coating.

[0020] Preferably, in step two, when the heating furnace is heated to 1050-1150℃, it is held at that temperature for 45-65 minutes, and the high-temperature section of the (α+β) phase region is 10-50℃ below the β transformation temperature.

[0021] Preferably, the specific operation steps in step three are as follows: the forged alloy is placed in a heating furnace and heated to 20-40°C above the silicide dissolution temperature for 1-2 hours for solution treatment, followed by water quenching.

[0022] Preferably, the specific operation steps of step four are as follows: the alloy is subjected to one pass of multi-directional forging in the low-temperature section of the (α+β) phase region, the deformation speed is 1-3 mm / min, the deformation amount of each pass is controlled at 50-70%, and each pass consists of three passes.

[0023] Preferably, the low-temperature region of the (α+β) phase is 100-200℃ below the β transition temperature.

[0024] Therefore, the present invention employs the above-mentioned short-process preparation technology for high-temperature titanium alloys containing nano-silicides and ultrafine grains, which has the following beneficial effects:

[0025] 1. A pioneering approach was proposed to perform long-term solution cooling and quenching after billet forging. This step allows the matrix to obtain a metastable martensite structure with high-density dislocations. During low-temperature, low-strain, multi-directional forging, the metastable martensite can rapidly induce phase transformation in the alloy, promote grain refinement, and form ultrafine grains. At the same time, the formation of the metastable martensite structure also reduces the deformation resistance of the alloy during low-temperature forging, thereby reducing the risk of cracking during the forging process.

[0026] 2. Forging in the low-temperature range of the (α+β) phase region improved the size and distribution of silicides in the alloy, solving the problem of large-sized silicides precipitated at the α grain boundaries and phase boundaries of the matrix during forging. The silicides precipitated at the grain boundaries, phase boundaries, and within the grains of the alloy are all nanoscale and uniformly distributed, successfully controlling the production of nanoscale silicides in high-temperature α titanium alloys.

[0027] 3. Significantly shortens the process flow. In existing technologies, multiple forging processes are required to refine the grain size of titanium alloys, and it cannot guarantee that the silicides precipitated at grain boundaries, phase boundaries, and within grains will be nanoscale. This invention, however, requires only one multi-directional forging process to achieve the precipitation of ultrafine grains and nanoscale silicides. This reduces the process flow and effectively improves the strength and plasticity of the alloy. The technical solution of this invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0028] Figure 1 This is the BSE diagram of the as-cast alloy in Example 1 of the short-process preparation process of high-temperature titanium alloy containing nano-silicides and ultrafine grains according to the present invention.

[0029] Figure 2 This is the BSE diagram after billet forging in Example 1 of the short-process preparation process of high-temperature titanium alloy containing nano-silicides and ultrafine grains of the present invention.

[0030] Figure 3 This is a BSE diagram after one-pass multi-directional forging of a high-temperature titanium alloy containing nano-silicides and ultrafine grains, according to an embodiment of the present invention. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0032] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0033] This invention provides a short-process preparation technology for high-temperature titanium alloys containing nano-silicides and ultrafine grains, comprising the following steps:

[0034] Step 1: Preparing the ingot

[0035] Raw materials are weighed and ingots are prepared by vacuum induction melting. The raw materials are weighed according to the following components by weight percentage: 5.7-6.5 wt% Al, 2.5-3.5 wt% Sn, 0.8-1.2 wt% Mo, 0.8-1.2 wt% Nb, 0.8-1.2 wt% W, 7.0-9.5 wt% Zr, 0.35-0.53 wt% Si, 0-0.2 wt% C, with the remainder being Ti and other unavoidable impurity elements.

[0036] Step 2: Forging the billet

[0037] After the alloy surface is forged, apply an anti-oxidation coating and let it dry completely. Then wrap it with asbestos and place it in a heating furnace. Heat it to 1050-1150℃ and hold it for 45-65 minutes. Perform billet forging in the high-temperature section of the (α+β) phase region (10-50℃ below the β transformation temperature).

[0038] Step 3: Solution cooling and quenching

[0039] The forged alloy is placed in a heating furnace and heated to 20-40°C above the silicide dissolution temperature for 1-2 hours for solution treatment, followed by water quenching.

[0040] Step 4: One-stage isothermal multi-directional forging

[0041] After quenching in step three, the alloy surface is coated with Ti1200 anti-oxidation coating. Once dry, the alloy is wrapped in asbestos and placed in a heating furnace for one pass of isothermal multi-directional forging. The alloy is forged in the low-temperature region of the (α+β) phase (100-200℃ below the β transformation temperature) in one pass of multi-directional forging. The deformation rate is 1-3 mm / min, and the deformation amount is controlled at 50-70% for each pass. Each pass consists of three passes.

[0042] Example 1

[0043] This invention provides a short-process preparation technology for high-temperature titanium alloys containing nano-silicides and ultrafine grains, comprising the following steps:

[0044] Step 1: Use sponge titanium, high-purity tin, aluminum, zirconium, and crystalline silicon particles. The refractory metal elements Mo, Nb, and W are added in the form of Al-Mo alloys, Al-Nb alloys, and Al-W alloys. The weight percentages of the components in the high-temperature titanium alloy are: Al: 6%, Sn: 2.6%, Mo: 1%, Nb: 1%, W: 1%, Zr: 9%, Si: 0.45%, C: 0.2%, with the balance being Ti and other unavoidable impurity elements.

[0045] Step 2: Add all the sponge titanium, high-purity tin, aluminum, zirconium, crystalline silicon, Al-Mo alloy, Al-Nb alloy and Al-W alloy weighed in Step 1 into a vacuum induction melting furnace and perform three vacuum induction melting processes to obtain a near-α high-temperature titanium alloy ingot. The metallographic determination of the alloy shows that the β transformation temperature is 1060℃ and the silicide dissolution temperature is 1180℃.

[0046] Figure 1 The image shows the microstructure of the initial as-cast alloy. The initial structure is Widmanstätten structure with a β grain size of 230 μm and an α lamellar thickness of 3 μm. There is no silicide precipitation in the as-cast alloy.

[0047] Step 3: Coat the surface of the ingot obtained in Step 2 with Ti1200 anti-oxidation coating. After it dries completely, wrap it with asbestos and place it in a heating furnace to heat it to 1050℃ and hold it for 60 minutes. Then, forge the ingot to a rough shape, with a deformation of 65%. Then, place the forged alloy in a heating furnace to heat it to 1200℃ and hold it for 80 minutes, followed by water quenching.

[0048] Figure 2 The image shows the microstructure of the alloy after forging. The microstructure transforms into a basketweave structure, with finer β grains (109 μm) and shorter α lamellae (2 μm thickness) with a shorter aspect ratio. The white bright spots in the image are silicides, shaped like short rods with a size of 2.34 μm, precipitated mainly at grain and phase boundaries, with fewer intragranular precipitates and uneven distribution.

[0049] Step 4: Apply Ti1200 anti-oxidation coating to the surface of the alloy after quenching in Step 3. After it dries completely, wrap the alloy with asbestos and place it in a heating furnace for a first isothermal multi-directional forging. Place the alloy in a box furnace, adjust the furnace temperature to 900℃, hold for 20 minutes, and then place the alloy in a mold for the first forging. The deformation speed is 2 mm / min, and the deformation amount is 50%.

[0050] Immediately after the first forging, the alloy is placed in a heating furnace and held for 20 minutes. Then, the alloy is rotated 90° and placed into a mold for the second forging, with a deformation rate of 2 mm / min and a deformation amount of 50%. Immediately after the second forging, the alloy is placed in a heating furnace, with the temperature also controlled at 900℃ and held for 20 minutes. Then, the alloy is rotated 90° and placed into a mold for the third forging, with a deformation rate of 2 mm / min and a deformation amount of 50%. At this point, one isothermal multi-directional forging is completed, and the alloy is air-cooled to room temperature.

[0051] Figure 3 (a) in the figure is the microstructure of the alloy after one isothermal multi-directional forging. Figure 3(b) is an enlarged view of (a). After isothermal multi-directional forging, the alloy undergoes complete dynamic recrystallization. As shown in (a), the alloy's microstructure has been transformed into a completely equiaxed microstructure. In (b), the black part is the equiaxed α phase, and the large, irregularly shaped white part is the incompletely transformed β phase. The residual β phase and the equiaxed primary α phase are small in size, with a grain size of 0.59 μm, <1 μm, which is ultrafine. The white spots in the figure are precipitated silicides, which are elliptical in shape and 107 nm in size. They are precipitated at both the α / β grain boundaries and within the grains and are evenly distributed.

[0052] The alloy obtained after the above treatment exhibits complete dynamic recrystallization, resulting in a fully equiaxed microstructure. The residual β phase and equiaxed primary α phase are fine-sized, with a grain size of 0.84 μm. Silicides precipitate in the matrix both at grain boundaries and within the grains, with a size of 280 nm. At room temperature, the tensile strength is 1483 MPa, and the plasticity is 7.2%.

[0053] Example 2

[0054] This invention provides a short-process preparation technology for high-temperature titanium alloys containing nano-silicides and ultrafine grains, comprising the following steps:

[0055] Step 1: Use sponge titanium, high-purity tin, aluminum, zirconium, and crystalline silicon particles. The refractory metals Mo, Nb, and W are added in the form of Al-Mo alloys, Al-Nb alloys, and Al-W alloys. The weight percentages of the components in the high-temperature titanium alloy are: Al: 5.8%, Sn: 2.8%, Mo: 1.1%, Nb: 1.1%, W: 0.8%, Zr: 8.5%, Si: 0.4%, C: 0.02%, with the balance being Ti and other unavoidable impurity elements.

[0056] Step 2: Add all the sponge titanium, high-purity tin, aluminum, zirconium, crystalline silicon, Al-Mo alloy, Al-Nb alloy, and Al-W alloy weighed in Step 1 to a vacuum induction melting furnace and perform three vacuum induction melting processes to obtain a near-α high-temperature titanium alloy ingot. Metallographic determination shows that the alloy's β-transformation temperature is 990℃ and the silicide dissolution temperature is 1170℃.

[0057] Step 3: Coat the surface of the ingot obtained in Step 2 with Ti1200 anti-oxidation coating. After it dries completely, wrap it with asbestos and place it in a heating furnace to heat it to 970℃ and hold it for 90 minutes. Then, perform billet forging on the ingot, with a deformation of 60%. Then, place the forged alloy in a heating furnace to heat it to 1210℃ and hold it for 90 minutes, followed by water quenching.

[0058] Step 4: Apply Ti1200 anti-oxidation coating to the surface of the alloy after quenching in Step 3. After it dries completely, wrap the alloy with asbestos and place it in a heating furnace for a first isothermal multi-directional forging. Place the alloy in a box furnace, adjust the furnace temperature to 800℃, hold for 20 minutes, and then place the alloy in a mold for the first forging. The deformation speed is 1mm / min and the deformation amount is 50%.

[0059] Immediately after the first forging, the alloy is placed in a heating furnace and held at 800℃ for 20 minutes. Then, the alloy is rotated 90° and placed in a mold for the second forging, with a deformation rate of 1 mm / min and a deformation amount of 50%. Immediately after the second forging, the alloy is placed in a heating furnace and held at 800℃ for 20 minutes. Then, the alloy is rotated 90° and placed in a mold for the third forging, with a deformation rate of 1 mm / min and a deformation amount of 50%. At this point, one isothermal multi-directional forging is completed, and the alloy is air-cooled to room temperature.

[0060] The alloy obtained after the above treatment has an equiaxed microstructure, with fine-sized residual β phase and equiaxed primary α phase, and a grain size of 0.88 μm. Silicides precipitate in the matrix both at grain boundaries and within grains, with a size of 110 nm. At room temperature, it has a tensile strength of 1370 MPa and a plasticity of 7.2%.

[0061] Example 3

[0062] This invention provides a short-process preparation technology for high-temperature titanium alloys containing nano-silicides and ultrafine grains, comprising the following steps:

[0063] Step 1: Use sponge titanium, high-purity tin, aluminum, zirconium, and crystalline silicon particles. The refractory metal elements Mo, Nb, and W are added in the form of Al-Mo alloys, Al-Nb alloys, and Al-W alloys. The weight percentages of the components in the high-temperature titanium alloy are: Al: 5.5%, Sn: 2.5%, Mo: 0.8%, Nb: 0.8%, W: 0.8%, Zr: 8%, Si: 0.4%, C: 0.02%, with the balance being Ti and other unavoidable impurity elements.

[0064] Step 2: Add all the sponge titanium, high-purity tin, aluminum, zirconium, crystalline silicon, Al-Mo alloy, Al-Nb alloy, and Al-W alloy weighed in Step 1 to a vacuum induction melting furnace and perform three vacuum induction melting processes to obtain a near-α high-temperature titanium alloy ingot. Metallographic determination shows that the β transformation temperature of the alloy is 940℃, and the silicide dissolution temperature is 1140℃.

[0065] Step 3: Coat the surface of the ingot obtained in Step 2 with Ti1200 anti-oxidation coating. After it dries completely, wrap it with asbestos and place it in a heating furnace to heat it to 930℃ and hold it for 90 minutes. Then, perform billet forging on the ingot, with a deformation of 70%. Then, place the forged alloy in a heating furnace to heat it to 1170℃ and hold it for 120 minutes, followed by water quenching.

[0066] Step 4: Apply Ti1200 anti-oxidation coating to the surface of the alloy after quenching in Step 3. After it dries completely, wrap the alloy with asbestos and place it in a heating furnace for a first isothermal multi-directional forging. Place the alloy in a box furnace, adjust the furnace temperature to 750℃, hold for 25 minutes, and then place the alloy in a mold for the first forging. The deformation speed is 2mm / min and the deformation amount is 65%.

[0067] Immediately after the first forging, the alloy is placed in a heating furnace and held at 750℃ for 25 minutes. Then, the alloy is rotated 90° and placed in a mold for the second forging, with a deformation rate of 2 mm / min and a deformation amount of 50%. Immediately after the second forging, the alloy is placed in a heating furnace and held at 750℃ for 25 minutes. Then, the alloy is rotated 90° and placed in a mold for the third forging, with a deformation rate of 2 mm / min and a deformation amount of 50%. At this point, one isothermal multi-directional forging is completed, and the alloy is air-cooled to room temperature.

[0068] The alloy obtained after the above treatment has an equiaxed microstructure, with fine-sized residual β phase and equiaxed primary α phase, and a grain size of 0.79±0.15 μm. Silicides precipitate in the matrix both at grain boundaries and within grains, with a size of 134 nm. At room temperature, it has a tensile strength of 1450 MPa and a plasticity of 7.6%.

[0069] The above three examples all demonstrate that the grain size of the alloy prepared by this method is <1μm, which is ultrafine, and the silicide size is all at the nanoscale, which achieves a good match with the strength and plasticity of the alloy.

[0070] Comparative Example 1

[0071] The alloy is identical to the Ti-Al-Sn-Zr-Mo-Nb-W-Si-C system of Example 1, except that the contents of other elements are the same, with Zr content being 6.5% and Si content being 0.2%. The β-transformation temperature of the alloy was determined to be 985℃ and the silicide dissolution temperature to be 1165℃ by metallographic analysis.

[0072] The alloy preparation steps are as follows: (1) Alloy melting. Sponge titanium, high-purity tin, aluminum, zirconium, crystalline silicon grains, and Al-Mo, Al-Nb, and Al-W alloys are used. The alloy ingots are obtained by melting three times in a vacuum induction furnace. (2) Forging. The ingots are held at 1050℃ for 45 min and then forged at 960℃ with a deformation of 60%. (3) Solution quenching. The ingots are solution quenched at 1060℃ for 90 min and then water-cooled. (4) One-pass isothermal multi-directional forging at 800℃.

[0073] Microstructural observation showed that as the Zr and Si content decreased, the grain size increased, with an average size >1 μm, preventing the formation of ultrafine grains. The amount and size of the precipitated silicides decreased compared to Example 1. The room temperature tensile strength and plasticity of the alloy were both lower than those of Example 1. As can be seen from Example 1 and this comparative example, lower Zr and Si content in the alloy leads to an increase in grain size, preventing the formation of ultrafine grains, and simultaneously reducing the amount and size of silicides. Both room temperature strength and plasticity decrease.

[0074] Comparative Example 2

[0075] The composition is the same as that of the Ti-Al-Sn-Zr-Mo-Nb-W-Si-C system of the alloy in Example 1. The difference is that after the blanking and forging in step 3, only solution treatment is performed and the blank is air-cooled to room temperature.

[0076] Microstructural observation revealed the presence of an untransformed β phase in the matrix. A single multi-directional forging process was insufficient to achieve complete dynamic recrystallization of the alloy, resulting in deformed grains with increased grain size (average >3 μm). Numerous and coarse-sized silicides precipitated at grain boundaries and phase boundaries (average >1 μm), while fewer and slightly larger silicides precipitated within the grains. The room-temperature tensile strength and plasticity of the alloy were also lower than in Example 1. As demonstrated in Example 1 and this comparative example, solution treatment alone cannot form ultrafine grains, and the advantage of forming nanoscale silicides in the matrix is ​​lost. The effects of grain refinement strengthening and precipitation strengthening are not significant.

[0077] Therefore, the present invention employs the above-mentioned short-process preparation process for high-temperature titanium alloys containing nano-silicides and ultrafine grains, which can obtain ultrafine grains and stably precipitate nano-silicides in near-α high-temperature titanium alloys, thereby achieving the goal of improving the strength and plasticity of titanium alloys.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A short process for the production of high temperature titanium alloys containing nanosilicides and ultrafine grains, characterized by: Includes the following steps: Step 1: Preparing the ingot Raw materials are weighed and ingots are prepared by vacuum induction melting. In step one, the ingredients are prepared according to the following elemental weight percentages: 5.7-6.5 wt% Al, 2.5-3.0 wt% Sn, 0.8-1.2 wt% Mo, 0.8-1.2 wt% Nb, 0.8-1.2 wt% W, 8.5-9.5 wt% Zr, 0.35-0.53 wt% Si, 0-0.2 wt% C, with the remainder being Ti and other unavoidable impurity elements. Step 2: Forging the billet The surface of the ingot is coated with an anti-oxidation coating. After it dries completely, it is wrapped with asbestos and placed in a heating furnace to be heated and kept at that temperature for a period of time. The ingot is then forged in the high-temperature section of the (α+β) phase region. In step two, when the heating furnace is heated to 1050-1150℃, it is held for 45-65 minutes. The high-temperature section of the (α+β) phase region is 10-50℃ below the β transformation temperature. Step 3: Solution cooling and quenching The forged alloy is placed in a heating furnace and heated to a certain temperature for solution treatment and held at that temperature for a period of time, and then water-cooled quenching is performed. The specific steps in step three are as follows: the forged alloy is placed in a heating furnace and heated to 20-40°C above the silicide dissolution temperature for 1-2 hours, followed by water quenching. Step 4: One-stage isothermal multi-directional forging After the alloy surface is quenched in step three, an anti-oxidation coating is applied. After it dries completely, the alloy is wrapped in asbestos and placed in a heating furnace for one round of isothermal multi-directional forging. The specific operation steps of step four are as follows: the alloy is subjected to one pass of multi-directional forging in the low temperature section of the (α+β) phase region, the deformation speed is 1-3 mm / min, the deformation amount of each pass is controlled at 50-70%, and each pass consists of three passes. The low-temperature section of the (α+β) phase region in step four is 100-200℃ below the β transition temperature.

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