A TC21 titanium alloy forging method

Abstract

The invention discloses a TC21 titanium alloy forging method, comprising: β Forging in the (α+β) zone at ‑(30~60)℃, temperature is T β +(10~15)℃β zone forging, temperature is T β Forging in the (α+β) zone at ‑(30~60)℃, with the total deformation controlled at 5%~20%, finally obtains the organizational characteristics of the forging: small β grain size; fully broken grain boundaries; the α phase broken into short rods in the grain, with the width of the α layer between 3~5μm and the aspect ratio <15. This organization can greatly improve the strength level of the alloy, while obtaining high plasticity and high fracture toughness. Its excellent comprehensive performance enables it to meet the performance requirements of the new aircraft forging standards, solving the problem of unsatisfactory microstructure of TC21 titanium alloy forgings after production by traditional process routes.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy hot processing, and in particular to a TC21 titanium alloy forging method. Background Art

[0002] TC21 titanium alloy is a (α+β) two-phase titanium alloy independently developed in my country. Due to its high strength, high toughness and low crack growth rate, it is widely used as forgings in the aviation field in important load-bearing structural parts such as wing joints, fuselages and engine suspension joints.

[0003] At present, the traditional process route for TC21 titanium alloy forgings in China is quasi-β forging (forging heating temperature is T β +15℃)+double annealing. Because the heating forging process is carried out in the β phase region, the final forgings are likely to form the following organizational characteristics: coarse β grains, relatively complete grain boundaries, and the aspect ratio of the lamellar α phase within the grains>15, resulting in insufficient strength and poor plasticity of the forgings. Summary of the invention

[0004] In view of this, the main purpose of the present invention is to provide a TC21 titanium alloy forging method, which can solve the problems of insufficient strength and poor plasticity of forgings in the prior art.

[0005] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A TC21 titanium alloy forging method comprises the following steps:

[0007] S1, (α+β) zone forging, the bar is forged at a temperature of T β -(30-60)℃ furnace heating, heating coefficient is 0.6-0.8min / mm, then forging, each fire deformation is controlled between 20% and 45%, to obtain billet A;

[0008] S2. Preheat the forging tooling to 350-450°C;

[0009] S3, β zone forging, the billet A is heated to a temperature of T β +(10~15)℃ furnace heating, heating coefficient is 0.2~0.4min / mm, after heating, take out of the furnace, wrap with heat preservation bag, put into the furnace again, β +(10-15)°C, heat at 0.1min / mm, and then use the preheated tooling die in S2 for hot die forging, with the deformation controlled between 25% and 35%, to obtain blank B;

[0010] S4, (α+β) zone forging, the blank B is forged at a temperature of T β-(30-60)°C furnace heating, heating coefficient of 0.6-0.8min / mm, forging tooling die preheated according to step S2, two-phase zone forging, deformation controlled between 5% and 20%, to obtain billet C;

[0011] S5, primary annealing, performing a primary annealing treatment on the blank C, the primary annealing temperature is (T β -60)℃~(T β -80)℃, take out of the furnace and air cool to room temperature to obtain blank D;

[0012] S6, secondary annealing, performing secondary annealing treatment on the billet D, the secondary annealing temperature is 500° C. to 650° C., and air-cooling to room temperature after being taken out of the furnace to obtain a final forging;

[0013] Wherein, the Tβ is the β phase transition temperature of the titanium alloy.

[0014] Preferably, the forging heating temperature in step S1 is T β -35℃, heating coefficient is 0.65min / mm.

[0015] Preferably, the forging heating temperature in step S3 is T β +10℃, heating coefficient is 0.35min / mm.

[0016] Preferably, the deformation amount in step S4 is 10%.

[0017] Preferably, it is characterized in that the cooling method in step S5 is pad-up air cooling.

[0018] Preferably, the thermal insulation bag in step S3 is composed of aluminum silicate fiber felt and a high-temperature adhesive.

[0019] Preferably, the final forging temperature in S1, S3 and S4 is ≥820°C.

[0020] A TC21 titanium alloy forging method of the present invention has the following beneficial effects:

[0021] This application uses a temperature of T β -(30~60)℃、T β +(10~15)℃、T β-(30~60)℃ forging, the total deformation is controlled at 5%~20%, which solves the problem of unsatisfactory microstructure of TC21 titanium alloy forgings after production by traditional process routes. The morphology characteristics of lamellar α phase and β grains are optimized, and finally the characteristics of the organization are obtained: small β grain size; fully broken grain boundaries; lamellar α phase broken into short rods in the crystal, the width of α lamellae is between 3~5μm, and the aspect ratio is <15. This organization can greatly improve the strength level of the alloy, while obtaining high plasticity and high fracture toughness. Its comprehensive performance is excellent, so that it can meet the performance requirements of the new aircraft forging standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 The microstructure of a TC21 titanium alloy forging forged by a TC21 titanium alloy forging method according to an embodiment of the present disclosure;

[0024] Figure 2 This is the microstructure of TC21 titanium alloy forgings obtained by traditional forging process. DETAILED DESCRIPTION

[0025] The TC21 titanium alloy forging method of the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments of the present invention.

[0026] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0029] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0030] The present invention provides a technical solution: a TC21 titanium alloy forging method, comprising the following steps:

[0031] S1, (α+β) zone forging, the bar is forged at a temperature of T β -(30-60)℃ furnace heating, heating coefficient is 0.6-0.8min / mm, then forging, multiple forging can be performed, deformation of each forging is controlled between 20% and 45%, to obtain billet A;

[0032] S2. Preheat the forging tooling to 350-450°C;

[0033] S3, β zone forging, the billet A is heated to T β +(10~15)℃ furnace heating, heating coefficient is 0.2~0.4min / mm, after heating, take out of the furnace, wrap with heat preservation bag, put into the furnace again, β+(10~30)℃, keep warm at 0.1min / mm, use the preheated tooling die in S2 for hot die forging, and control the deformation between 25% and 35% to obtain blank B; at T β When heating forging at +(10~15)℃, the temperature is close to the phase transformation point. The billet will continue to cool after being taken out of the furnace, which may lead to the appearance of a two-phase zone structure. Wrapping it with an insulation bag will greatly alleviate the decrease in billet temperature and increase the β zone forging window. Compared with wrapping it with an insulation bag during initial heating, wrapping it with an insulation bag before entering the furnace for the second time can significantly reduce the total heating time and avoid the growth and coarsening of billet grains due to long-term heating. Compared with normal temperature tooling, using tooling after high-temperature preheating can prevent the decrease in surface temperature of the billet during forging and avoid the appearance of a cold film layer on the billet.

[0034] S4, (α+β) zone forging, the blank B is forged at a temperature of T β -(30~60)℃ furnace heating, heating coefficient is 0.6~0.8min / mm, forging tooling die is preheated according to step S2, two-phase zone forging is carried out, multiple fire forging can be carried out to ensure that the total deformation is controlled between 5% and 20%, and blank C is obtained; the total deformation is controlled between 5% and 20% forging, which can fully break the β grain boundary, and the lamellar α phase in the crystal will undergo dynamic recrystallization again, and finally form a short rod-shaped lamellar structure with a width of 3~5μm and an aspect ratio of <15. When the deformation is less than 5%, the β grain boundary cannot be fully broken, and the strength data of the forging is low; when the deformation is greater than 20%, the β grain boundary will be fully broken, but the lamellar α phase in the crystal will undergo violent dynamic recrystallization again, resulting in excessive breaking of the lamellar structure, and the fracture toughness of the final forging will be significantly reduced.

[0035] S5, primary annealing, annealing the blank C once, the annealing temperature is (T β -60)℃~(T β -80)℃, take out of the furnace and air cool to room temperature to obtain blank D;

[0036] S6, secondary annealing, performing secondary annealing treatment on the billet D, the secondary annealing temperature is 500°C to 650°C, and air cooling to room temperature after being taken out of the furnace to obtain the final forging;

[0037] Among them, the T β is the β phase transformation temperature of titanium alloy.

[0038] The forging heating temperature in step S1 is T β At -35℃, the optimal heating coefficient is 0.65min / mm.

[0039] The forging heating temperature in step S3 is T β +10℃, the heating coefficient is 0.35min / mm which is the best.β +10℃ is the key parameter. When heated at this temperature, the original β grains of the titanium alloy fail to grow completely, which is conducive to grain refinement and can ensure that forging starts in the β phase region. During the temperature drop process, lamellar α phases are precipitated in the crystals. The lamellar α phases undergo dynamic recrystallization to form a certain woven structure, which is conducive to the improvement of fracture toughness. If this temperature is higher than 10℃, the original β grains will grow significantly, which is not conducive to the subsequent forging crushing, and the comprehensive mechanical properties will decrease; if this temperature is lower than 10℃, the subsequent forging temperature drop process will cause the forging process to appear too much in the two-phase region, which is not conducive to the formation of lamellar structure, and even eventually obtain equiaxed structure, at which time the fracture toughness will be significantly reduced.

[0040] The cooling method in step S5 is air cooling.

[0041] In step S3, the heat-insulating bag is composed of aluminum silicate fiber felt and high-temperature binder. Aluminum silicate fiber is a new type of inorganic fiber material with excellent high-temperature stability and is used for heat insulation of forgings.

[0042] The final forging temperature in S1, S3 and S4 is ≥820℃. If the final forging temperature is too low, the risk of billet cracking will increase.

[0043] The embodiment of the present invention discloses a TC21 titanium alloy forging method, and the present invention is further described in detail in conjunction with the embodiment below. It should be understood that the specific embodiment described herein is only used to explain the present invention, and is not used to limit the present invention.

[0044] Example 1

[0045] S1. Place the raw materials in an electric furnace and heat to T β -35℃, heating coefficient is 0.65min / mm, after heating and heat preservation, the raw materials are taken out and forged by 31.5MN fast forging machine, one-fire forming, deformation amount is 30%, final forging temperature is ≥820℃, and blank A is obtained;

[0046] S2. Preheat the forging tooling die to 400°C;

[0047] S3, T the blank A in step S1 β Forging at the above temperature, the forging heating temperature is T β +10℃, heating coefficient is 0.3min / mm, blank A is quickly taken out from the heating furnace, wrapped with a heat-insulating bag, and put into the furnace again. β After heating at +10℃ and keeping warm at 0.1min / mm, forging was performed using a 31.5MN fast forging machine and the preheated die in S2. This forging temperature is lower than that of the traditional process, which is beneficial to preventing the rapid growth of the original β grains. The billet transfer is ≤30s, the deformation is controlled at 30%, and the final forging temperature is ≥820℃ to obtain billet B.

[0048] S4, the blank B in step S2 is again forged in the (α+β) zone, and the forging heating temperature is T β -30℃, heating coefficient is 0.7min / mm, forging tooling die is preheated according to step S2, billet B is quickly taken out from the heating furnace, and two-phase zone forging is performed once by using a 31.5MN fast forging machine, the deformation is 10%, and the final forging temperature is ≥820℃, to obtain billet C;

[0049] S5, performing an annealing treatment on the blank C in step S3, using a heat treatment electric furnace with a uniformity of ±5°C, an annealing temperature of 900°C, a furnace transfer time of ≤25s, and air cooling to room temperature to obtain a blank D;

[0050] S6. Perform secondary annealing on the blank D in step S4 at a temperature of 595° C. in a heat treatment electric furnace with a uniformity of ±5° C. and air cool to room temperature after being taken out of the furnace to obtain a final forging.

[0051] Among them, T β It is the β phase transformation temperature of titanium alloy, and the measured value is 965℃.

[0052] The microstructure of the TC21 titanium alloy forging prepared by the forging method provided in Example 1 is shown in FIG. Figure 1 As can be seen from the figure, the β grain size is small, the grain boundary is fully broken, and the crystal is broken into short rod-shaped lamellar α phase. The width of the α lamella is between 3 and 5 μm, and the aspect ratio is <15. Figure 2 The microstructure of the TC21 titanium alloy forging obtained by the traditional forging process. As can be seen from the figure, the β grains are coarse, have relatively complete grain boundaries, and the aspect ratio of the lamellar α phase within the grain is greater than 15, resulting in insufficient strength and poor plasticity in the forging performance.

[0053] Physical and chemical tests: The TC21 forgings obtained in Example 1 were sampled and inspected. The mechanical properties, microstructure, macrostructure, ultrasonic inspection and other items were all qualified. The tensile strength, yield strength, fracture toughness, elongation and cross-sectional shrinkage were all higher than the standard values, which can meet the performance requirements of the new aircraft forging standards. The room temperature tensile properties and fracture toughness data of Example 1 are shown in Table 1.

[0054] Table 1 Room temperature tensile properties and fracture toughness data of Example 1

[0055] direction Rm / Mpa Rp0.2 / Mpa A%(5D) Z％ <![CDATA[K IC / MPa·m 1 / 2 (LT)]]> vertical 1141 1034 13.9 22.7 83.6 horizontal 1138 1045 14.2 21.3 82.1 high 1134 1029 11.3 20.3 /

[0056] Example 2

[0057] S1. Place the raw materials in an electric furnace and heat to T β-35℃, heating coefficient is 0.65min / mm, after heating and heat preservation, the raw materials are taken out and forged by 31.5MN fast forging machine, one-fire forming, deformation amount is 30%, final forging temperature is ≥820℃, and blank A is obtained;

[0058] S2. Preheat the forging tooling die to 400°C;

[0059] S3, T the blank A in step S1 β Forging at the above temperature, the forging heating temperature is T β +10℃, heating coefficient is 0.3min / mm, blank A is quickly taken out from the heating furnace, wrapped with a heat-insulating bag, and put into the furnace again. β +10℃, keep warm at 0.1min / mm, and forge with a 31.5MN fast forging machine and the preheated die in S2. This forging temperature is lower than the traditional process, which is conducive to preventing the rapid growth of the original β grains. The billet transfer is ≤30s, the deformation is controlled at 30%, and the final forging temperature is ≥820℃ to obtain billet B; S4, the billet B in step S2 is forged in the (α+β) zone again, and the forging heating temperature is T β -30℃, heating coefficient is 0.7min / mm, forging tooling die is preheated according to step S2, billet B is quickly taken out from the heating furnace, and two-phase zone forging is performed with a 31.5MN fast forging machine, deformation is 5%, and final forging temperature is ≥820℃, to obtain billet C;

[0060] S5, performing an annealing treatment on the blank C in step S3, using a heat treatment electric furnace with a uniformity of ±5°C, an annealing temperature of 900°C, a furnace transfer time of ≤25s, and air cooling to room temperature to obtain a blank D;

[0061] S6. Perform secondary annealing on the blank D in step S4 at a temperature of 595° C. in a heat treatment electric furnace with a uniformity of ±5° C. and air cool to room temperature after being taken out of the furnace to obtain a final forging.

[0062] The TC21 forgings obtained in Example 2 were sampled and inspected, and the room temperature tensile properties and fracture toughness data are shown in Table 2.

[0063] Table 2 Room temperature tensile properties and fracture toughness data of Example 2

[0064] direction Rm / Mpa Rp0.2 / Mpa A%(5D) Z％ <![CDATA[K IC / MPa·m 1 / 2 (LT)]]> vertical 1118 1001 9.9 20.6 88.6 horizontal 1116 1010 12.9 23.6 93.1 high 1087 968 11.8 25.8 /

[0065] Example 3

[0066] S1. Place the raw materials in an electric furnace and heat to T β-35℃, heating coefficient is 0.65min / mm, after heating and heat preservation, the raw materials are taken out and forged by 31.5MN fast forging machine, one-fire forming, deformation amount is 30%, final forging temperature is ≥820℃, and blank A is obtained;

[0067] S2. Preheat the forging tooling die to 400°C;

[0068] S3, T the blank A in step S1 β Forging at the above temperature, the forging heating temperature is T β +10℃, heating coefficient is 0.3min / mm, blank A is quickly taken out from the heating furnace, wrapped with a heat-insulating bag, and put into the furnace again. β Heating at +10°C, keeping warm at 0.1min / mm, forging with a 31.5MN fast forging machine and the preheated die in S2, the billet transfer is ≤30s, the deformation is controlled at 30%, and the final forging temperature is ≥820°C to obtain billet B;

[0069] S4, the blank B in step S2 is again forged in the (α+β) zone, and the forging heating temperature is T β -30℃, heating coefficient is 0.7min / mm, forging tooling is preheated according to step S2, billet B is quickly taken out from the heating furnace, and two-phase zone forging is performed with a 31.5MN fast forging machine, deformation is 20%, and final forging temperature is ≥820℃ to obtain billet C;

[0070] S5, performing an annealing treatment on the blank C in step S3, using a heat treatment electric furnace with a uniformity of ±5°C, an annealing temperature of 900°C, a furnace transfer time of ≤25s, and air cooling to room temperature to obtain a blank D;

[0071] S6. Perform secondary annealing on the blank D in step S4 at a temperature of 595° C. in a heat treatment electric furnace with a uniformity of ±5° C. and air cool to room temperature after being taken out of the furnace to obtain a final forging.

[0072] The TC21 forgings obtained in Example 3 were sampled and inspected, and the room temperature tensile properties and fracture toughness data are shown in Table 3.

[0073] Table 3 Room temperature tensile properties and fracture toughness data of Example 3

[0074] direction Rm / Mpa Rp0.2 / Mpa A%(5D) Z％ <![CDATA[K IC / MPa·m 1 / 2 (LT)]]> vertical 1132 1040 14.9 30.3 74.1 horizontal 1145 1051 12.5 31.9 65.5 high 1135 1051 11.8 28.3 /

[0075] Example 4

[0076] S1. Place the raw materials in an electric furnace and heat to T β-35℃, heating coefficient is 0.65min / mm, after heating and heat preservation, the raw materials are taken out and forged by 31.5MN fast forging machine, one-fire forming, deformation amount is 30%, final forging temperature is ≥820℃, and blank A is obtained;

[0077] S2. Preheat the forging tooling die to 400°C;

[0078] S3, T the blank A in step S1 β Forging at the above temperature, the forging heating temperature is T β +15℃, heating coefficient is 0.3min / mm, blank A is quickly taken out from the heating furnace, wrapped with a heat preservation bag, and put into the furnace again. β Heating at +15°C, keeping warm at 0.1min / mm, forging with a 31.5MN fast forging machine and the preheated die in S2, the billet transfer is ≤30s, the deformation is controlled at 30%, and the final forging temperature is ≥820°C to obtain billet B;

[0079] S4, the blank B in step S2 is again forged in the (α+β) zone, and the forging heating temperature is T β -30℃, heating coefficient is 0.7min / mm, forging tooling is preheated according to step S2, billet B is quickly taken out from the heating furnace, 31.5MN fast forging is used for two-phase zone forging, deformation is 5%, final forging temperature is ≥820℃, and billet C is obtained;

[0080] S5, performing an annealing treatment on the blank C in step S3, using a heat treatment electric furnace with a uniformity of ±5°C, an annealing temperature of 900°C, a furnace transfer time of ≤25s, and air cooling to room temperature to obtain a blank D;

[0081] S6. Perform secondary annealing on the blank D in step S4 at a temperature of 595° C. in a heat treatment electric furnace with a uniformity of ±5° C. and air cool to room temperature after being taken out of the furnace to obtain a final forging.

[0082] The TC21 forgings obtained in Example 4 were sampled and inspected, and the room temperature tensile properties and fracture toughness data are shown in Table 4.

[0083] Table 4 Room temperature tensile properties and fracture toughness data of Example 4

[0084] direction Rm / Mpa Rp0.2 / Mpa A%(5D) Z％ <![CDATA[K IC / MPa·m 1 / 2 (LT)]]> vertical 1103 986 14.4 24.6 89.8 horizontal 1101 982 10.8 21.6 97.2 high 1102 986 13 29.8 /

[0085] Example 5

[0086] S1. Place the raw materials in an electric furnace and heat to T β-35℃, heating coefficient is 0.65min / mm, after heating and heat preservation, the raw materials are taken out and forged by 31.5MN fast forging machine, one-fire forming, deformation amount is 30%, final forging temperature is ≥820℃, and blank A is obtained;

[0087] S2. Preheat the forging tooling die to 400°C;

[0088] S3, T the blank A in step S1 β Forging at the above temperature, the forging heating temperature is T β +15℃, heating coefficient is 0.3min / mm, blank A is quickly taken out from the heating furnace, wrapped with a heat preservation bag, and put into the furnace again. β Heating at +15°C, keeping warm at 0.1min / mm, forging with a 31.5MN fast forging machine and the preheated die in S2, the billet transfer is ≤30s, the deformation is controlled at 30%, and the final forging temperature is ≥820°C to obtain billet B;

[0089] S4, the blank B in step S2 is again forged in the (α+β) zone, and the forging heating temperature is T β -30℃, heating coefficient is 0.7min / mm, forging tooling is preheated according to step S2, billet B is quickly taken out from the heating furnace, 31.5MN fast forging is used for two-phase zone forging, deformation is 10%, final forging temperature is ≥820℃, and billet C is obtained;

[0090] S5, performing an annealing treatment on the blank C in step S3, using a heat treatment electric furnace with a uniformity of ±5°C, an annealing temperature of 900°C, a furnace transfer time of ≤25s, and air cooling to room temperature to obtain a blank D;

[0091] S6. Perform secondary annealing on the blank D in step S4 at a temperature of 595° C. in a heat treatment electric furnace with a uniformity of ±5° C. and air cool to room temperature after being taken out of the furnace to obtain a final forging.

[0092] The TC21 forgings obtained in Example 5 were sampled and inspected, and the room temperature tensile properties and fracture toughness data are shown in Table 5.

[0093] Table 5 Room temperature tensile properties and fracture toughness data of Example 5

[0094] direction Rm / Mpa Rp0.2 / Mpa A%(5D) Z％ <![CDATA[K IC / MPa·m 1 / 2 (LT)]]> vertical 1106 1009 11.2 27.9 87.6 horizontal 1133 1038 14.4 24.8 84.6 high 1136 1024 12.5 23.8 /

[0095] Example 6

[0096] S1. Place the raw materials in an electric furnace and heat to T β-35℃, heating coefficient is 0.65min / mm, after heating and heat preservation, the raw materials are taken out and forged by 31.5MN fast forging machine, one-fire forming, deformation amount is 30%, final forging temperature is ≥820℃, and blank A is obtained;

[0097] S2. Preheat the forging tooling die to 400°C;

[0098] S3, T the blank A in step S1 β Forging at the above temperature, the forging heating temperature is T β +15℃, heating coefficient is 0.3min / mm, blank A is quickly taken out from the heating furnace, wrapped with a heat preservation bag, and put into the furnace again. β Heating at +15°C, keeping warm at 0.1min / mm, forging with a 31.5MN fast forging machine and the preheated die in S2, the billet transfer is ≤30s, the deformation is controlled at 30%, and the final forging temperature is ≥820°C to obtain billet B;

[0099] S4, the blank B in step S2 is again forged in the (α+β) zone, and the forging heating temperature is T β -30℃, heating coefficient is 0.7min / mm, forging tooling die is preheated according to step S2, billet B is quickly taken out from the heating furnace, and two-phase zone forging is performed with a 31.5MN fast forging machine, deformation is 20%, and final forging temperature is ≥820℃, to obtain billet C;

[0100] S5, performing an annealing treatment on the blank C in step S3, using a heat treatment electric furnace with a uniformity of ±5°C, an annealing temperature of 900°C, a furnace transfer time of ≤25s, and air cooling to room temperature to obtain a blank D;

[0101] S6. Perform secondary annealing on the blank D in step S4 at a temperature of 595° C. in a heat treatment electric furnace with a uniformity of ±5° C. and air cool to room temperature after being taken out of the furnace to obtain a final forging.

[0102] The TC21 forgings obtained in Example 6 were sampled and inspected, and the room temperature tensile properties and fracture toughness data are shown in Table 6.

[0103] Table 6 Room temperature tensile properties and fracture toughness data of Example 6

[0104] direction Rm / Mpa Rp0.2 / Mpa A%(5D) Z％ <![CDATA[K IC / MPa·m 1 / 2 (LT)]]> vertical 1133 1048 14.2 28.7 69.9 horizontal 1146 1062 12.5 30.3 65.0 high 1139 1044 10.4 23.7 /

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention.

Claims

1. A TC21 titanium alloy forging method, characterized in that: The following steps are involved: S1, (α+β) zone forging, the bar is forged at a temperature of T β -(30-60)℃ furnace heating, heating coefficient is 0.6-0.8min / mm, then forging, each fire deformation is controlled between 20% and 45%, to obtain billet A; S2. Preheat the forging tooling to 350-450°C; S3, β zone forging, the billet A is heated to a temperature of T β +(10~15)℃ furnace heating, heating coefficient is 0.2~0.4min / mm, after heating, take out of the furnace, wrap with heat preservation bag, put into the furnace again, β +(10-15)°C, heat at 0.1min / mm, and then use the preheated tooling die in S2 for hot die forging, with the deformation controlled between 25% and 35%, to obtain blank B; S4, (α+β) zone forging, the blank B is forged at a temperature of T β -(30-60)°C furnace heating, heating coefficient of 0.6-0.8min / mm, forging tooling die preheated according to step S2, two-phase zone forging, deformation controlled between 5% and 20%, to obtain billet C; S5, primary annealing, performing a primary annealing treatment on the blank C, the primary annealing temperature is (T β -60)℃~(T β -80)℃, take out of the furnace and air cool to room temperature to obtain blank D; S6, secondary annealing, performing secondary annealing treatment on the billet D, the secondary annealing temperature is 500° C. to 650° C., and air-cooling to room temperature after being taken out of the furnace to obtain a final forging; The T β is the β phase transformation temperature of titanium alloy.

2. The TC21 titanium alloy forging method according to claim 1, characterized in that: The forging heating temperature in step S1 is T β -35℃, heating coefficient is 0.65min / mm.

3. The TC21 titanium alloy forging method according to claim 1, characterized in that: The forging heating temperature in step S3 is T β +10℃, heating coefficient is 0.35min / mm.

4. The TC21 titanium alloy forging method according to claim 1, characterized in that: The cooling method in step S5 is air cooling.

5. The TC21 titanium alloy forging method according to claim 1, characterized in that: The thermal insulation bag described in step S3 is composed of aluminum silicate fiber felt and high-temperature adhesive.

6. The TC21 titanium alloy forging method according to claim 1, characterized in that: The final forging temperature in S1, S3 and S4 is ≥820°C.

7. The TC21 titanium alloy forging method according to claim 1, characterized in that: The deformation amount in step S4 is 10%.

Images