Ti2AlNb alloy disc forge piece and preparation method thereof

Abstract

The invention relates to a Ti2AlNb alloy disc forge piece and a preparation method thereof, and belongs to the technical field of materials. The preparation method of the Ti2AlNb alloy disc forge piece comprises the steps that A, the B2-> B2 + alpha2 actual measurement phase transformation point temperature TB2 of a Ti2AlNb alloy raw material is tested, and the Ti2AlNb alloy raw material is a cylindrical bar containing a B2 + alpha2 + O three-phase equal structure; b, the Ti2AlNb alloy raw material is forged and formed in a B2 + alpha2 two-phase region, and a binary structure containing B2 + alpha2 + O three phases is obtained; and C, the Ti2AlNb subjected to forging forming is sequentially subjected to homogenization heat treatment, solid solution heat treatment and aging heat treatment. According to the method, precise regulation and control of the Ti2AlNb alloy disc forging structure are achieved, energy consumption is low, and the obtained forging is good in comprehensive performance.

Description

TECHNICAL FIELD

[0001] The application relates to a Ti2AlNb alloy disc forging and a preparation method thereof, and belongs to the technical field of materials. BACKGROUND

[0002] As a new generation of lightweight high-temperature structural material, Ti2AlNb-based alloy has become a key candidate material (such as high-pressure compressor disc, casing and other rotating parts) for aero-engine serving in a 650-750 DEG C environment, due to its low density, excellent high-temperature specific strength, creep resistance and oxidation resistance. However, the alloy is a long-range ordered intermetallic compound, and the complex multi-component phase equilibrium (involving the coexistence of B2 / β phase, O phase and alpha2 phase) leads to that the microstructure is extremely sensitive to the hot working parameters. This characteristic makes the Ti2AlNb alloy forging face the core bottleneck of difficult microstructure regulation and unbalanced performance matching in the heat treatment process - the traditional solid solution + aging double heat treatment is difficult to coordinate the contradiction between room temperature plasticity, fracture toughness and high-temperature strength, and endurance performance.

[0003] The existing heat treatment scheme for Ti2AlNb alloy has significant limitations:

[0004] Fracture toughness and comprehensive performance imbalance: although CN114790524A proposes high-temperature die forging above the beta phase transition point by 50-100 DEG C + triple heat treatment to improve fracture toughness, the method needs to be forged in the beta single-phase region (> 1050 DEG C), which is high in energy consumption and has a high risk of microstructure coarsening. Although the composition range (Al: 9.5-13%, Nb: 38-46%) is relatively wide, the process focuses on a single toughness index, and the problem of synergistic optimization of high-temperature strength and plasticity is not solved, and the thermal stability performance of the embodiments is poor, and the elongation and area reduction of the sample after 650 DEG C for 100 h heat exposure decreases greatly.

[0005] Endurance performance and room temperature plasticity are difficult to be considered: CN112063945A designs a three-stage heat treatment (30-5 DEG C below the beta phase transition point -> 20 DEG C above the first stage -> 700-820 DEG C aging) to improve the endurance creep performance, but the homogenization temperature of the first stage (30-5 DEG C below the phase transition point) is still high, which leads to insufficient retention of primary alpha2 / O phase (volume fraction > 10%), which limits the plasticity improvement space, and the energy consumption is high. The reported room temperature elongation (12.5%) and endurance life (650 DEG C / 360 MPa about 166 h) are better than those of the traditional process, but the uniformity control of the microstructure of the thick section of the forging is not involved.

[0006] Plate process cannot be transplanted to forgings: CN119736568A develops multi-stage heat treatment (960-1030℃→880-950℃→760-840℃) for 0.8-4mm thick superplastic sheet, and optimizes the strength and toughness matching through multi-scale O-phase lath distribution. However, there are great differences between thin plates and forgings with thickness of 15-60mm: firstly, the rolling strain of sheet is uniform, while the forgings are prone to have structure gradient due to uneven deformation; secondly, the cooling rate of thin plate is fast, and the phase transformation kinetics of thick section of forgings is significantly different during heat treatment cooling, so directly applying the sheet process will lead to core structure coarsening and uneven performance.

[0007] In particular, as the core load-bearing component of an aero-engine, the disc forging needs to meet strict indicators in terms of room temperature high plasticity, sufficient fracture toughness, 650℃ high temperature strength, creep resistance, and microstructure stability after long-term thermal exposure.

[0008] Currently, there is no mature heat treatment scheme that can systematically solve the above-mentioned needs, which seriously restricts the engineering application of Ti2AlNb alloy in aero rotating parts. SUMMARY

[0009] The first object of the present application is to provide a method for preparing a Ti2AlNb alloy disc forging.

[0010] To achieve the first object of the present application, the method comprises:

[0011] A. Testing the B2→B2+α2 measured phase transition point temperature T of the Ti2AlNb alloy raw material B2 , the Ti2AlNb alloy raw material is a cylindrical rod containing B2+α2+O equiaxed structure;

[0012] B. Forming the Ti2AlNb alloy raw material in the B2+α2 two-phase region to obtain a duplex structure containing B2+α2+O three phases;

[0013] C. The forged Ti2AlNb is sequentially subjected to homogenization heat treatment, solid solution heat treatment and aging heat treatment;

[0014] The temperature of the homogenization heat treatment is T B2 -60~T B2 -45℃, and the holding time is [(0.7-1.0)D+(60-120)]min;

[0015] The temperature of the solid solution heat treatment is T B2 -110~T B2 -85℃, and the holding time is [(0.7-1.0)D+120]min;

[0016] The temperature of the aging heat treatment is TB2 -280~T B2 -235℃, the holding time is 12h~24h;

[0017] The D is the maximum effective heat transfer cross-sectional dimension of the Ti2AlNb alloy disc forging, in mm.

[0018] The T B2 -60 refers to the measured phase transition point temperature T B2 minus 60℃, T B2 -45℃ refers to the measured phase transition point temperature T B2 minus 45℃; T B2 -110 refers to the measured phase transition point temperature T B2 minus 110℃, T B2 -85 refers to the measured phase transition point temperature T B2 minus 85℃; T B2 -280 refers to the measured phase transition point temperature T B2 minus 280℃, T B2 -235 refers to the measured phase transition point temperature T B2 minus 235℃.

[0019] The duplex structure containing B2+α2+O three phases is that equiaxed α2 and O phase lamellas are distributed in the B2 phase matrix.

[0020] The homogenization heat treatment is carried out in the B2+α2 two-phase region, the solid solution heat treatment is carried out in the B2+α2+O three-phase region, and the aging heat treatment is carried out in the B2+O two-phase region.

[0021] The heat treatment of the application can adopt a large industrial resistance furnace, the electric furnace meets or is superior to the II type standard of GJB standard, and the electric furnace precision is ±5℃.

[0022] In one specific embodiment, the chemical composition of the Ti2AlNb is:

[0023] Al: 9.00~11.90 Wt.%; Nb: 38.60~44.60 Wt.%; Zr≤1.50 Wt.%; Mo≤1.50 Wt.%; Ni≤0.10 Wt.%;

[0024] Si≤0.10 Wt.%; Fe≤0.30 Wt.%; C≤0.10 Wt.%; O≤0.10 Wt.%; N≤0.02 Wt.%; H≤0.01 Wt.%; the rest is Ti and inevitable impurities.

[0025] In one specific embodiment, the T B2 The test includes:

[0026] (a) setting the B2→B2+α2 out-of-factory phase transition point T0 of the Ti2AlNb alloy raw material B2 as a reference; within the range of ±20℃, setting 5-8 heating temperature points at temperature intervals of 5-10℃; B2

[0027] (b) according to the number of heating temperature points, taking the corresponding fraction of the Ti2AlNb alloy raw material sample, and then heating each Ti2AlNb alloy raw material sample to a different temperature point set in step (a) and holding for t minutes, where the holding time t=k*d+c, d is the maximum effective heat transfer cross-sectional dimension of the sample in mm; k is 0.7-1.0 min / mm, and c is 30-40 min;

[0028] (c) immediately after holding, quenching to room temperature in water; detecting the phase composition of each sample after quenching; and according to the phase composition, determining the actual phase transition point T of the alloy by metallographic method B2 .

[0029] In one specific embodiment, the forging forming uses ordinary forging, hot die forging or isothermal forging;

[0030] The preheating temperature of the forging die or tooling is 300-450℃; the heating temperature for forging is T B2 -60 to T B2 -30℃, and the heating coefficient is 0.7-1.0 min / mm; after the Ti2AlNb alloy raw material is heated, the transfer time of the Ti2AlNb alloy raw material is controlled to be ≤90s; the pressing speed is 2-10 mm / s, and the deformation amount in a single heating cycle is controlled to be 20%-60%; after N heating cycles, a Ti2AlNb alloy disc forging is finally obtained, where N is a natural number of 1 or more.

[0031] The T B2 -30℃ refers to the measured phase transition point temperature T B2 minus 30℃.

[0032] In one specific embodiment, the range of D is 15-60 mm.

[0033] In one specific embodiment, the heating coefficient of the homogenization heat treatment is 0.7-1.0 min / mm, and after the homogenization heat treatment holding ends, the cooling method is air cooling to room temperature.

[0034] In one specific embodiment, the heating coefficient of the solid solution heat treatment is 0.7-1.0 min / mm, and after the solid solution heat treatment holding ends, the cooling method is water cooling, oil cooling or air cooling to room temperature, and the quenching delay time is ≤60s.

[0035] ​In one specific embodiment, the aging heat treatment is cooled to room temperature by air cooling after the holding period ends.

[0036] A second object of the present application is to provide a Ti2AlNb alloy disc forging.

[0037] To achieve the second object of the present application, the Ti2AlNb alloy disc forging is prepared by the method described above.

[0038] The microstructure of the forging is a three-state microstructure containing B2+α2+O phases, with a room temperature strength of 1080 MPa or more, a yield strength of 900 MPa or more, an elongation of 6% or more, and a reduction of area of 8% or more.

[0039] The forging has a high temperature strength of 720 MPa or more at 750℃, a yield strength of 550 MPa or more, an elongation of 12% or more, and a reduction of area of 18% or more.

[0040] The forging has a high temperature strength of 600 MPa or more at 800℃, a yield strength of 380 MPa or more, an elongation of 16% or more, and a reduction of area of 28% or more.

[0041] The forging has a 20h or more persistent fracture time at 750℃, 180 MPa for 12h or more at 800℃, and a hardness of 300-350 HBW at room temperature.

[0042] In one specific embodiment, the α2 is an equiaxed α2 phase with a size ranging from 2.0 to 2.2 microns.

[0043] Advantages:

[0044] 1.The present application quickly determines the phase transition point of Ti2AlNb alloy raw materials, effectively controls the forging forming points of Ti2AlNb alloy disc forgings and the required organizational features, and completes the organizational preparation before heat treatment; then, using the triple heat treatment technology of homogenization + solid solution + aging, the forging-specific heat treatment process parameters of Ti2AlNb alloy disc forgings with different effective section thicknesses are quickly determined, the organization of the Ti2AlNb alloy disc forgings is accurately and effectively controlled through triple heat treatment, and the three-state organization of the equiaxed α2 phase, the Rim-O phase, the coarse lamellar O phase and the fine lamellar O phase uniformly and continuously distributed on the B2 phase matrix with a size of 1.7-2.2 microns is obtained, the proportion and form of each phase are moderate, which can make the strengthening effect of the Ti2AlNb alloy disc forgings optimal, and the obtained Ti2AlNb alloy disc forgings have good strength and plasticity matching, high high-temperature strength and endurance performance, and excellent comprehensive performance. The present application effectively solves the problems of Ti2AlNb alloy disc forging heat treatment process design difficulty, tedious process parameter setting, forging organization control difficulty and performance difficulty, realizes the accurate regulation and control of the organization of Ti2AlNb alloy disc forgings, guarantees the stability of the forging organization and the consistency of the performance, the required equipment and related conditions of the process are simple, the production cost is low, and the engineering application of Ti2AlNb alloy disc forgings can be realized.

[0045] 2.The heat treatment temperature of the present application is low, and the energy consumption is low.

[0046] 3.The organization of the high-performance Ti2AlNb alloy disc forgings of the present application is a three-state organization containing B2+α2+O three phases, the room temperature strength is above 1080 MPa, the yield strength is above 900 MPa, the elongation is above 6%, and the reduction of area is above 8%; the 750℃ high-temperature strength is above 720 MPa, the yield strength is above 550 MPa, the elongation is above 12%, and the reduction of area is above 18%; the 800℃ high-temperature strength is above 600 MPa, the yield strength is above 380 MPa, the elongation is above 16%, and the reduction of area is above 28%; the 750℃, 250Mpa endurance fracture time is above 20h, the 800℃, 180Mpa endurance is above 12h, and in addition, the room temperature hardness is between 300-350HBW. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 The microstructure photograph of the Ti2AlNb alloy bar used for forging of the present application embodiment 1.

[0048] Figure 2 The microstructure photograph of the Ti2AlNb alloy forging of the present application embodiment 1.

[0049] Figure 3The microstructure photograph of the Ti2AlNb alloy forge piece after triple strengthening heat treatment of embodiment 1 of the present application. DETAILED DESCRIPTION

[0050] To achieve the first object of the present application, the method comprises:

[0051] A. Testing the B2→B2+α2 measured phase transition point temperature T of the Ti2AlNb alloy raw material, wherein the Ti2AlNb alloy raw material is a cylindrical rod containing B2+α2+O three-phase equiaxed structure; B2

[0052] B. Forging the Ti2AlNb alloy raw material in the B2+α2 two-phase region to obtain a dual-state structure containing B2+α2+O three phases;

[0053] C. sequentially performing homogenization heat treatment, solid solution heat treatment and aging heat treatment on the forged Ti2AlNb alloy;

[0054] The homogenization heat treatment temperature is T B2 -60~T B2 -45℃, and the holding time is [(0.7~1.0)D+(60~120)] min;

[0055] The solid solution heat treatment temperature is T B2 -110~T B2 -85℃, and the holding time is [(0.7~1.0)D+120] min;

[0056] The aging heat treatment temperature is T B2 -280~T B2 -235℃, and the holding time is 12h~24h;

[0057] The D is the maximum effective heat transfer cross-sectional dimension of the Ti2AlNb alloy disc forge piece, and the unit is mm.

[0058] The dual-state structure containing B2+α2+O three phases is that the equiaxed α2 and O phase lamellae are distributed in the B2 phase matrix.

[0059] The homogenization heat treatment is performed in the B2+α2 two-phase region, the solid solution heat treatment is performed in the B2+α2+O three-phase region, and the aging heat treatment is performed in the B2+O two-phase region.

[0060] The heat treatment of the present application can adopt a large industrial resistance furnace, and the electric furnace meets or is superior to the GJB standard II standard, and the electric furnace precision is ±5℃.

[0061] In a specific embodiment, the chemical composition of the Ti2AlNb is:

[0062] ​Al: 9.00-11.90 Wt.%; Nb: 38.60-44.60 Wt.%; Zr≤1.50 Wt.%; Mo≤1.50 Wt.%; Ni≤0.10 Wt.%;

[0063] Si≤0.10 Wt.%; Fe≤0.30 Wt.%; C≤0.10 Wt.%; O≤0.10 Wt.%; N≤0.02 Wt.%; H≤0.01 Wt.%; the rest is Ti and inevitable impurities.

[0064] In a specific embodiment, the T B2 The test includes:

[0065] (a) taking Ti2AlNb alloy raw material as a reference, and setting 5-8 heating temperature points at a temperature interval of 5-10°C in the range of T0 B2 ±20°C, where T0 B2 is the B2→B2+α2 out-of-factory phase transition point of the Ti2AlNb alloy raw material;

[0066] (b) according to the number of heating temperature points, taking corresponding portions of Ti2AlNb alloy raw material samples, and then heating each Ti2AlNb alloy raw material sample to a different temperature point set in step (a) and holding for t minutes, where t=k*d+c, d is the maximum effective heat transfer cross-sectional dimension of the sample in mm, k is 0.7-1.0 min / mm, and c is 30-40 min;

[0067] (c) immediately quenching to room temperature after holding, detecting the phase composition of each sample after quenching, and determining the actual phase transition point T B2 of the alloy by metallographic method according to the phase composition.

[0068] In a specific embodiment, the forging forming uses ordinary forging, hot die forging or isothermal forging.

[0069] The preheating temperature of the forging die or tooling is 300-450°C, the heating temperature for forging is T B2 -60-T B2 -30°C, the heating coefficient is 0.7-1.0 min / mm, the Ti2AlNb alloy raw material is forged after heating, the transfer time of the Ti2AlNb alloy raw material is controlled to be ≤90 s, the pressing speed is 2-10 mm / s, and the deformation amount in a single fire is controlled to be 20%-60%; after N times of forging, a Ti2AlNb alloy disc forging is finally obtained, where N is a natural number of 1 or more.

[0070] In a specific embodiment, the range of D is 15-60 mm.

[0071] In a specific embodiment, the heating coefficient of the homogenization heat treatment is 0.7-1.0 min / mm, and the homogenization heat treatment is cooled to room temperature by air cooling after the holding.

[0072] In a specific embodiment, the heating coefficient of the solution heat treatment is 0.7-1.0 min / mm, and the solution heat treatment is cooled to room temperature by water cooling, oil cooling or air cooling after the holding, and the quenching delay time is ≤60 s.

[0073] In a specific embodiment, the aging heat treatment is cooled to room temperature by air cooling after the holding.

[0074] To achieve the second object of the present application, the Ti2AlNb alloy disc forging is prepared by the above method.

[0075] The microstructure of the forging is a three-state microstructure containing B2+α2+O three phases, the room temperature strength is above 1080 MPa, the yield strength is above 900 MPa, the elongation is above 6%, and the reduction of area is above 8%.

[0076] The high temperature strength of the forging at 750℃ is above 720 MPa, the yield strength is above 550 MPa, the elongation is above 12%, and the reduction of area is above 18%.

[0077] The high temperature strength of the forging at 800℃ is above 600 MPa, the yield strength is above 380 MPa, the elongation is above 16%, and the reduction of area is above 28%.

[0078] The forging has a 20h or more persistent fracture time at 750℃ and 250MPa, a 12h or more persistent time at 800℃ and 180MPa, and a hardness of 300-350HBW at room temperature.

[0079] In a specific embodiment, the α2 is an equiaxed α2 phase with a size range of 2.0-2.2 microns.

[0080] The specific embodiments of the present application are further described below in conjunction with examples, and the present application is not limited in the scope of the examples.

[0081] Example 1

[0082] The chemical composition and mass fraction of the Ti2AlNb alloy in the experiment are shown in Table 1 below:

[0083] Table 1. Composition of Ti2AlNb alloy (wt. %)

[0084]

[0085] Step 1: as Figure 1As shown, the Ti2AlNb alloy cylindrical rod used in this experiment contains B2+α2+O three-phase equiaxed structure; the B2→B2+α2 measured phase transition point is tested and obtained, the test uses 7 Ti2AlNb alloy samples taken from the same raw material, with the B2→B2+α2 factory phase transition point 1058℃ as the starting temperature, the temperature gradient of each 5℃ in the range of T0 B2 ±15℃ is set for the heating temperature of 7 phase transition point samples, and the holding time is 47min (holding time t=k*d+c, where d is 15mm, k is 0.8min / mm, and c is 35min), and after the holding is completed, it is rapidly cooled to room temperature by water cooling, and then the phase composition of the 7 samples is detected to determine the measured phase transition point temperature T B2 is 1060℃;

[0086] Step 2: The Ti2AlNb alloy cylindrical rod / blank is formed by hot die forging on a 200MN hydraulic press, and the forging is carried out in the B2+α2 two-phase region; the tool preheating temperature is 300℃, and the die preheating temperature is 450℃; the heating temperature for forging is 1010℃, and the heating coefficient is 0.8min / mm; after the Ti2AlNb alloy cylindrical rod is heated, the Ti2AlNb alloy cylindrical rod is controlled to be transported for 46s; the press pressing speed is 5mm / s, and the single-fire deformation amount is controlled to be 35%; after 2-fire blanking+1-fire die forging, a Ti2AlNb alloy disc forging with a diameter of 600mm and an effective heat transfer section size of 55mm is finally obtained. As shown in Figure 2 , the B2+α2+O three-phase duplex structure is obtained after forging, that is, equiaxed α2 and O phase lamellae are distributed in the continuous B2 phase matrix, and the α2 phase in the structure is fine equiaxed and uniformly distributed on the B2 phase matrix;

[0087] Step 3: The Ti2AlNb alloy disc forging is subjected to homogenization heat treatment, the homogenization heat treatment is carried out in the B2+α2 two-phase region, the homogenization heat treatment heating temperature is 1010℃, the heating coefficient is 0.8min / mm, and the holding time is 124min, and after the holding is completed, it is cooled to room temperature by air cooling;

[0088] Step 4: The Ti2AlNb alloy disc forging is subjected to solid solution heat treatment, the solid solution heat treatment is carried out in the B2+α2+O three-phase region, the solid solution heat treatment heating temperature is 960℃, the heating coefficient is 0.8min / mm, the holding time is 164min, and after the holding is completed, it is rapidly cooled to room temperature by oil cooling, and the quenching delay time is 40s;

[0089] Step 5: The Ti2AlNb alloy disc forging is subjected to aging heat treatment, the aging heat treatment is carried out in the B2+O two-phase region, the aging heat treatment heating temperature is 810℃, the holding time is 20h, and after the holding is completed, it is cooled to room temperature by air cooling.

[0090] The step 3 homogenization heat treatment, the step 4 solid solution heat treatment and the step 5 aging heat treatment all adopt a large industrial resistance furnace, and the electric furnace meets or is superior to the II type standard of GJB standard, and the electric furnace precision is ± 5 DEG C.

[0091] As shown in Figure 3 The triple heat treatment of homogenization + solid solution + aging of the application precisely and effectively controls the microstructure of the Ti2AlNb alloy disc forging, obtains the three-state microstructure of the equiaxial α2 phase, the Rim-O phase, the coarse lamellar O phase and the fine lamellar O phase uniformly and continuously distributed on the B2 phase matrix, the proportion and the form of each phase are moderate, the strengthening effect of the alloy disc forging can be optimized, the obtained Ti2AlNb alloy disc forging has good strength and plasticity matching as shown in the following table 2, higher high-temperature strength as shown in the following table 3, and higher endurance performance as shown in the following table 4, and excellent comprehensive performance as shown in the following tables 5-6.

[0092] Table 2 room temperature tensile properties of Ti2AlNb alloy forgings

[0093]

[0094] Table 3 high temperature tensile properties of Ti2AlNb alloy forgings

[0095]

[0096] Table 4 high temperature combined endurance properties of Ti2AlNb alloy forgings

[0097]

[0098] Table 5 thermal stability of Ti2AlNb alloy forgings

[0099]

[0100] Table 6 room temperature hardness of Ti2AlNb alloy forgings

[0101]

[0102] The heat treatment process design of the Ti2AlNb alloy disc forging is simple and convenient, the process parameter setting is convenient, the precise regulation and control of the microstructure of the Ti2AlNb alloy disc forging is realized, the stability of the microstructure and the performance consistency of the forging are effectively ensured, the required equipment and related conditions are easy to obtain, and the engineering application of the Ti2AlNb alloy disc forging is realized.

Claims

1. A method for preparing a Ti2AlNb alloy disc forging, characterized in that: The method comprises: A. Test the B2→B2+α2 phase transition temperature T of Ti2AlNb alloy raw material B2 The Ti2AlNb alloy raw material is a cylindrical rod containing a B2+α2+O three-phase equiaxed structure; B. Forging the Ti2AlNb alloy raw material in the B2+α2 two-phase region to obtain a dual-state structure containing B2+α2+O three-phases; C. The forged Ti2AlNb is subjected to homogenization heat treatment, solution heat treatment, and aging heat treatment in sequence; The temperature of the homogenization heat treatment is T B2 -60~T B2 -45℃, holding time is [(0.7~1.0)D+(60~120)]min; The temperature of the solution heat treatment is T B2 -110~T B2 -85℃, holding time is [(0.7~1.0)D+120]min; The temperature of the aging heat treatment is T B2 -280~T B2 -235℃, holding time is 12h~24h; The D is the maximum effective heat transfer cross-sectional dimension of the Ti2AlNb alloy disk forging, in mm.

2. The method for preparing a Ti2AlNb alloy disk forging according to claim 1, wherein: The chemical composition of the Ti2AlNb is: Al: 9.00~11.90Wt.%; Nb: 38.60~44.60Wt.%; Zr≤1.50Wt.%; Mo≤1.50Wt.%; Ni≤0.10Wt.%; Si≤0.10Wt.%; Fe≤0.30Wt.%; C≤0.10Wt.%; O≤0.10Wt.%; N≤0.02Wt.%; H≤0.01Wt.%; the rest are Ti and unavoidable impurities.

3. The method for preparing a Ti2AlNb alloy disk forging according to claim 1 or 2, characterized in that: The T B2 The tests include: (a) The B2→B2+α2 phase transition point T0 of Ti2AlNb alloy raw material B2 As the benchmark; at T0 B2 Within the range of ±20℃, 5 to 8 heating temperature points can be set at intervals of 5 to 10℃; (b) taking a corresponding number of Ti2AlNb alloy raw material samples according to the number of heating temperature points, and then heating each Ti2AlNb alloy raw material sample to a different temperature point set in step (a), holding the sample at the temperature for t minutes, where the holding time t = k*d + c, where d is the maximum effective heat transfer cross-section size of the sample, in mm; k is 0.7 to 1.0 min / mm, and c is 30 to 40 min; (c) immediately quenching the sample to room temperature after holding the temperature; detecting the phase composition of each sample after quenching; and determining the actual phase transition point T of the alloy by metallographic method based on the phase composition. B2 .

4. The method for preparing a Ti2AlNb alloy disk forging according to claim 1 or 2, characterized in that: The forging process uses conventional forging, hot die forging or isothermal forging; The preheating temperature of the forging die or tooling is 300-450℃; the heating temperature used for forging is T B2 -60~T B2 -30°C, a heating coefficient of 0.7 to 1.0 min / mm; forging is performed after the Ti2AlNb alloy raw material is heated, and the transfer time of the Ti2AlNb alloy raw material is controlled to be ≤90 seconds; a pressing speed is 2 to 10 mm / s, and the deformation amount per fire is controlled to be 20% to 60%; after N fires of forging, a Ti2AlNb alloy disc forging is finally obtained, where N is a natural number greater than 1.

5. The method for preparing a Ti2AlNb alloy disk forging according to claim 1 or 2, characterized in that: The range of D is 15 to 60 mm.

6. The method for preparing a Ti2AlNb alloy disk forging according to claim 1 or 2, characterized in that: The heating coefficient of the homogenization heat treatment is 0.7-1.0 min / mm, and after the homogenization heat treatment is completed, the heat preservation is cooled to room temperature by air cooling.

7. The method for preparing a Ti2AlNb alloy disk forging according to claim 1 or 2, characterized in that: The heating coefficient of the solution heat treatment is 0.7-1.0 min / mm. After the solution heat treatment is completed, it is cooled to room temperature by water cooling, oil cooling or air cooling. The quenching delay time is ≤60s.

8. The method for preparing a Ti2AlNb alloy disk forging according to claim 1 or 2, characterized in that: After the aging heat treatment is completed, the heat is cooled to room temperature by air cooling.

9. Ti2AlNb alloy disc forging, characterized in that: The Ti2AlNb alloy disc forging is prepared by the method described in any one of claims 1 to 8; The forging has a three-phase structure of B2+α2+O, a room temperature strength of more than 1080, a yield strength of more than 900 MPa, an elongation of more than 6%, and a cross-sectional shrinkage of more than 8%. The forging has a high temperature strength of 720 MPa or more at 750°C, a yield strength of 550 MPa or more, an elongation of 12% or more, and a cross-sectional shrinkage of 18% or more; The forging has a high temperature strength of 600 MPa or more at 800°C, a yield strength of 380 MPa or more, an elongation of 16% or more, and a cross-sectional shrinkage of 28% or more; The forging has a lasting fracture time of more than 20 hours at 750°C and 250 MPa, a lasting fracture time of more than 12 hours at 800°C and 180 MPa, and a room temperature hardness of 300-350 HBW.

10. The Ti2AlNb alloy disk forging according to claim 9, characterized in that: The α2 is an equiaxed α2 phase with a size range of 2.0 to 2.2 microns.

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