TC32 titanium alloy large-specification forged plate and preparation method thereof

Abstract

The invention provides a TC32 titanium alloy large-specification forged plate and a preparation method thereof. The preparation method comprises the following steps that S1, a TC32 titanium alloy cast ingot is subjected to repeated upsetting and drawing treatment at the temperature of 1000-1200 DEG C, and a cogged forging stock is obtained; s2, the cogged forging stock is sequentially subjected to first heating number upsetting and drawing treatment and second heating number upsetting and drawing treatment below a phase transformation point, a flat square is obtained through the first heating number upsetting and drawing treatment, the second heating number upsetting and drawing treatment is conducted according to the sequence of flat square upsetting, axial upsetting, axial drawing and flat square pressing, and a first flat blank is obtained; s3, the first flat blank is subjected to one-heating-number upsetting and drawing treatment above the phase transformation point, an obtained forging blank is subjected to recrystallization annealing treatment, and a second flat blank is obtained; and S4, the second flat blank is subjected to broadening and drawing-out treatment below the phase transformation point, machining is conducted, and the TC32 titanium alloy large-specification forged plate is obtained. By means of the method, accurate control over homogenization forging deformation of the large-specification plate blank is achieved, and the production period is shortened.

Description

Technical Field

[0001] The invention belongs to the field of metal material forging processing, and specifically relates to a TC32 titanium alloy large-size forging plate and a preparation method thereof. Background Art

[0002] TC32 titanium alloy is a new type of low-cost, high-comprehensive performance titanium alloy with a wide hot processing window, high strength, good plasticity, high fracture toughness and good fatigue resistance. Its comprehensive performance is significantly higher than that of the most widely used TC4 titanium alloy, and it is expected to become my country's new generation of backbone structure titanium alloy material.

[0003] In recent years, with the rapid development of aircraft design concepts, in order to improve the safety and reliability of aircraft and extend their service life, the main load-bearing components of titanium alloys have made a leap towards high performance, large-scale and integration. Therefore, the demand for the development and production of high-performance large-scale integral forgings for aircraft load-bearing structures is becoming more and more urgent.

[0004] At present, the blanks required for the development of large-scale integral forgings are generally realized by forging or rolling. The slabs produced by the rolling process have smooth surfaces, good quality, high forming efficiency, and can be manufactured in different sizes according to needs. However, it is difficult to accurately control the mechanical properties of the slabs produced by the rolling process, the consistency of the organizational properties is poor, and it is easy to form plate texture, which is difficult to meet the requirements of the consistency and stability of the organizational properties of high-comprehensive performance titanium alloy load-bearing components. In comparison, the consistency and stability of the organizational properties of the slabs produced by forging are better than those produced by rolling. However, due to the large difference in thickness, width and length of the forged plate, if the forging process design is unreasonable, it is easy to produce uneven deformation and deformation dead zone during the forging process. At the same time, the weight of the large-scale forging billet is large, so the deformation resistance during forging deformation is large, the forging fire is many, the equipment tonnage is high, the high and low multiple organizational refinement is difficult, and the production cycle of the slab is also long, and the production efficiency is low. Therefore, the current forging and rolling processes have limited the widespread application of large-size TC32 titanium alloy forgings in aviation main load-bearing components to varying degrees. It is urgent to design a more reasonable process route to solve the above problems. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a TC32 titanium alloy large-size forged plate and a preparation method thereof. The preparation method solves the technical problem of uniform structure and performance and batch stability of TC32 titanium alloy large-size forged plate by using fewer forging times.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for preparing a large-size forged plate of TC32 titanium alloy, comprising the following steps:

[0008] S1: repeatedly subjecting the TC32 titanium alloy ingot to a drawing treatment at 1000-1200°C to obtain a forged billet after blanking;

[0009] S2: performing a first-time drawing treatment and a second-time drawing treatment on the forged billet below the phase transformation point, wherein the first-time drawing treatment obtains a flat square, and the second-time drawing treatment is performed in the order of flat square roughening-axial roughening-axial drawing-pressing the flat square, and a first flat billet is obtained;

[0010] S3: performing a heat drawing treatment on the first slab above the phase transformation point, and performing a recrystallization annealing treatment on the obtained forging slab to obtain a second slab;

[0011] S4: The second flat billet is widened and elongated below the phase transformation point to obtain a large-size forged plate of TC32 titanium alloy.

[0012] Preferably, the repeated pulling and tucking treatment in step S1 is a two-fire pulling and tucking treatment, and the number of pulling and tucking treatments in each fire does not exceed three pulls and three tuckings.

[0013] Preferably, in each fire upsetting treatment, the single upsetting deformation is 35-55%, the pressing amount of each hammer is 20-50 mm, the pressing rate is 10-40 mm / s; and the final forging temperature is not less than 800°C.

[0014] Preferably, during the upsetting process in the repeated upsetting treatment in step S1, a circular tooling mold with a diameter of not less than 1500 mm is used.

[0015] Preferably, during the upsetting process of the repeated upsetting treatment in step S1, the upper hammer anvil presses the blank at a uniform speed.

[0016] Preferably, after the forging is opened in step S2, the forging billet is subjected to a first fire-drawing treatment and a second fire-drawing treatment in sequence at 15° C. to 50° C. below the phase transformation point.

[0017] Preferably, the number of pull-outs in the first fire-pulling treatment does not exceed three pull-outs and three pull-outs, and the number of pull-outs in the second fire-pulling treatment does not exceed two pull-outs and two pull-outs.

[0018] Preferably, in the first and second fire upsetting treatments, the single upsetting deformation is 40-60%, the pressing amount per hammer is 20-40 mm, the pressing rate is 15-30 mm / s; and the final forging temperature is not less than 800°C.

[0019] Preferably, the aspect ratio of the first flat blank is 1.5:1~3:1.

[0020] Preferably, step S3 performs a one-fire, two-hammer, two-draw treatment at 15°C to 35°C above the phase transformation point; in the said drawing treatment, the single roughening deformation is 20-35%; and the final forging temperature is not less than 800°C.

[0021] Preferably, the temperature of the recrystallization annealing treatment is 800-900° C., and the holding time is 180-360 min.

[0022] Preferably, in step S4, the second flat blank is subjected to a widening and lengthening treatment at 20°C to 50°C below the phase transformation point.

[0023] Preferably, the forging number of the widening and drawing treatment is 3 to 5, wherein the deformation during widening is 30 to 50%, and the deformation during drawing is 40 to 60%; and the final forging temperature is not less than 800°C.

[0024] Preferably, the widening is completed first in the forging process of the widening and lengthening treatment.

[0025] Preferably, in step S4, when the aspect ratio of the second slab is greater than 1.5, the portion of the slab to be forged last is wrapped with asbestos.

[0026] In a second aspect, the present invention provides a large-size forged plate of TC32 titanium alloy prepared according to the above-mentioned preparation method.

[0027] Preferably, the TC32 titanium alloy large-size forged plate has a length of 2500-3000 mm, a width of 1000-1500 mm, and a thickness of 150-200 mm.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention provides a preparation method of a large-size forged plate of a TC32 titanium alloy. The method uses a TC32 titanium alloy ingot with good fracture toughness and excellent processing performance as a preparation raw material. Firstly, the initial TC32 titanium alloy ingot is subjected to repeated upsetting and drawing treatment in a single-phase region at a high temperature (1000-1200°C) to fully break and refine the coarse original β grain structure; then, the first-fire upsetting and drawing treatment and the second-fire upsetting and drawing treatment are performed below the phase transformation point, so as to fully improve the structural uniformity of the slab, reduce the difference in the structural structure of the slab in different regions, and effectively eliminate the subsequent forging process. Anisotropy that may occur during the plate forming process; then, a fire-drawing treatment is carried out above the phase transformation point to further break and refine the grains of the slab. After forging, the slab is directly subjected to recrystallization annealing treatment. The purpose is to transform the relatively coarse deformed grains produced by the large deformation of the early slab into non-distorted grains through static recrystallization, further refine the grain structure, and improve the process plasticity; finally, a widening and drawing treatment is carried out below the phase transformation point to further refine and homogenize the microstructure to ensure the organizational consistency of the final TC32 titanium alloy large-size forged plate.

[0030] The large-size forged TC32 titanium alloy plate prepared by the preparation method provided by the present invention can have the following specifications: length of 2500-3000 mm, width of 1000-1500 mm, and thickness of 150-200 mm. In addition, after testing, the large-size forged TC32 titanium alloy plate has uniform high and low magnification structures in various parts after heat treatment, and the difference in mechanical properties is small, which shows that its structure and properties are uniform and consistent, and the batch stability is high.

[0031] In summary, the present invention combines the material flow characteristics of large-size forging plates during the free forging process, and realizes the precise control of the uniform forging deformation of large-size slabs. Compared with the prior art, it reduces the number of forging fires, shortens the production cycle, reduces production costs, and ensures the stability and consistency of the forging process of different furnace batches, thereby improving batch stability. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The present invention is designed to address the deficiencies in the above-mentioned prior art, and provides a method for preparing a large-sized forged plate of TC32 titanium alloy, the purpose of which is to solve the technical problems of uniform organization and performance and batch stability of large-sized forged plates of TC32 titanium alloy by reasonable design of the forging process and using fewer forging fires, break through the forging technology bottleneck of large-sized forged plates of titanium alloy, and meet the demand for large-sized integral titanium alloy forgings in the field of aerospace in my country. On this basis, the present invention provides a method for preparing a large-sized forged plate of TC32 titanium alloy, comprising the following steps:

[0034] S1: repeatedly subjecting the TC32 titanium alloy ingot to a drawing treatment at 1000-1200°C to obtain a forged billet after blanking;

[0035] S2: performing a first-time drawing treatment and a second-time drawing treatment on the forged billet below the phase transformation point, wherein the first-time drawing treatment obtains a flat square, and the second-time drawing treatment is performed in the order of flat square roughening-axial roughening-axial drawing-pressing the flat square, and a first flat billet is obtained;

[0036] S3: performing a heat drawing treatment on the first slab above the phase transformation point, and performing a recrystallization annealing treatment on the obtained forging slab to obtain a second slab;

[0037] S4: The second flat billet is widened and elongated below the phase transformation point to obtain a large-size forged plate of TC32 titanium alloy.

[0038] In the present invention, the TC32 titanium alloy ingot is preferably an ingot that has passed the composition inspection. The inspection standard refers to GB / T 26060 (titanium and titanium alloy ingots).

[0039] In the present invention, the repeated upsetting and drawing treatment in step S1 is preferably carried out at a high temperature, such as 1000-1200°C, preferably 1050-1150°C, in order to homogenize the structure of the ingot during high temperature insulation, and then fully crush and refine the coarse original β grain structure of the ingot. In the present invention, the repeated upsetting and drawing treatment is a two-fire upsetting and drawing treatment. Considering the relatively poor process plasticity of the TC32 titanium alloy ingot, the number of upsetting and drawing treatments per fire is preferably no more than three upsetting and three drawing.

[0040] Among them, in each fire-drawing treatment, the single roughing deformation is 35-55%, preferably 40-50%; the pressing amount of each hammer is 20-50 mm, preferably 30-40 mm; the pressing rate is 10-40 mm / s, preferably 20-30 mm / s; the final forging temperature is not less than 800°C. The present invention can ensure the comprehensive balance of dynamic recrystallization and grain nucleation and growth of TC32 titanium alloy structure by controlling the above-mentioned roughing deformation and the forging pressing rate of the drawing. The present invention does not make any special specific restrictions on the parameters of the drawing in each fire.

[0041] In some preferred embodiments of the present invention, when roughening is performed during the repeated upsetting treatment in step S1, a circular tooling mold with a diameter of not less than 1500 mm is preferably used to ensure uniform overall deformation of the entire ingot during the upsetting process, thereby avoiding the phenomenon of inconsistent deformation of the upsetting of the individual hammers due to the small size of the hammer anvil.

[0042] In some preferred embodiments of the present invention, when roughening is performed during the repeated upsetting treatment in step S1, the upper hammer anvil presses the billet in a uniform downward pressure manner so that the coarse structure of the ingot is more evenly crushed.

[0043] In the present invention, after the repeated upsetting and drawing treatments are completed, air cooling and surface grinding treatments are preferably performed to obtain the forged billet after opening.

[0044] In the present invention, after the forging billet after blanking is obtained through step S1, according to the present invention, the forging billet after blanking is subjected to the first fire drawing treatment and the second fire drawing treatment in sequence below the phase transformation point, wherein the first fire drawing treatment obtains a flat square, and the second fire drawing treatment is carried out in the order of flat square roughening-axial roughening-axial drawing-pressing the flat square, and the first flat billet is obtained. Among them, the present invention preferably controls the temperature at 15°C to 50°C below the phase transformation point, and more preferably at 20°C to 40°C below the phase transformation point, and sequentially performs the first fire drawing treatment and the second fire drawing treatment, and the control of the temperature is conducive to obtaining a more uniform microstructure.

[0045] In the present invention, unlike the conventional upsetting and drawing deformation of traditional titanium alloys, step S2 includes a first-fire upsetting and drawing treatment and a second-fire upsetting and drawing treatment. Among them, the first-fire upsetting and drawing treatment is mainly for upsetting on the streamline of the forging blank, the purpose of which is to further break up the structure and obtain a flat square when the forging is completed. The second-fire upsetting and drawing treatment adopts the sequence of flat square upsetting → axial upsetting → axial drawing → pressing the flat square for forging deformation. Through the one-time upsetting process in the above-mentioned second-fire upsetting and drawing treatment process, the deformation processing of the forging blank in the direction parallel to the streamline and perpendicular to the streamline is realized at the same time, which fully improves the uniformity of the structure of the forging blank, reduces the difference in the structure of the forging blank in different regions, and effectively eliminates the anisotropy that may occur in the subsequent forging plate forming process.

[0046] In the present invention, the number of pull-outs in the first fire treatment is preferably no more than three pull-outs, and the number of pull-outs in the second fire treatment is preferably no more than two pull-outs.

[0047] Among them, in the first fire upsetting treatment and the second fire upsetting treatment, the single upsetting deformation is 40~60%, preferably 45~55%; the pressing amount of each hammer is 20~40 mm, preferably 25~35 mm; the pressing rate is 15~30 mm / s, preferably 20~25 mm / s; the final forging temperature is not less than 800℃.

[0048] In the present invention, it is preferred that after the second drawing treatment is completed, air cooling and surface grinding are performed to obtain the first flat slab.

[0049] In the present invention, the aspect ratio of the first flat slab is preferably 1.5:1-3:1, and more preferably 2.0:1-2.5:1.

[0050] After obtaining the first flat slab, according to the present invention, the first flat slab is subjected to a one-fire, two-stirring and two-drawing treatment above the phase transformation point, and the obtained forging is subjected to a recrystallization annealing treatment to obtain the second flat slab.

[0051] In the present invention, it is preferred to perform a one-fire, two-upsetting, two-drawing upsetting treatment at 15°C to 35°C above the phase transformation point, and more preferably at 20°C to 25°C above the phase transformation point. In the upsetting upsetting treatment, the single upsetting deformation is 20-35%, preferably 25-30%; and the final forging temperature is not less than 800°C.

[0052] The present invention further breaks and refines the grains of the first flat slab by performing repeated upsetting deformation with a relatively small deformation amount at 15°C to 35°C above the phase transformation point.

[0053] In the present invention, the temperature of the recrystallization annealing treatment is 800-900° C., preferably 820-850° C.; the holding time is 180-360 min, preferably 200-300 min.

[0054] In the present invention, after the recrystallization annealing treatment is completed, water cooling and surface grinding treatment are preferably performed to obtain a second flat slab.

[0055] The present invention directly performs recrystallization annealing on the first slab after forging, with the purpose of transforming relatively coarse deformed grains generated by large deformation of the first slab into non-distorted grains through static recrystallization, further refining the grain structure and improving the process plasticity. Since the first slab after forging is directly subjected to recrystallization annealing, the production process of cooling and reheating the slab is simplified, the workload is reduced, the production efficiency is improved, and the production cost is reduced. At the same time, the recrystallization annealing is quickly followed by water cooling quenching, which inhibits the coarsening of the precipitated phase during the cooling process and obtains a fine and uniform structure.

[0056] After obtaining the second flat slab, according to the present invention, the second flat slab is subjected to a widening and lengthening treatment at 20°C to 50°C below the phase transition point, preferably at 30°C to 40°C below the phase transition point.

[0057] In the present invention, the forging times of the widening and drawing treatment are 3 to 5 times, preferably 4 to 5 times. The deformation during widening is 30 to 50%, preferably 35 to 45%; the deformation during drawing is 40 to 60%, preferably 45 to 50%; and the final forging temperature is not less than 800°C.

[0058] The present invention is beneficial to further refine and homogenize the microstructure by controlling the deformation amount of widening and elongation.

[0059] In the present invention, the metal has better fluidity at high temperature and is more easily extended in the streamline direction during drawing, so the deformation in the direction that is not easy to extend is completed first, that is, widening is completed first in each forging fire of the widening and drawing process.

[0060] In the above-mentioned widening and lengthening process, the aspect ratio of the second flat billet gradually increases and the forging deformation time gradually prolongs. The present invention preferably uses asbestos to wrap the last forged flat billet part when the aspect ratio of the second flat billet is greater than 1.5. This can effectively slow down the temperature drop of the last forged part and ensure the organizational consistency of the forging process.

[0061] It should be noted that after each forging fire in step S4, if no cracks appear in the second flat billet, the hot material can be returned to the furnace for heating and forging for the next fire.

[0062] Briefly, the present invention provides a method for preparing a large-size forged plate of TC32 titanium alloy, comprising the following steps:

[0063] S1: heating the ingot to between 1000°C and 1200°C, and performing two-stage forging to obtain a forged billet;

[0064] S2, heating the forging billet to 15°C to 50°C below the phase transformation point, and performing two-time repeated upsetting and drawing to obtain a flat billet; in the two-time repeated upsetting and drawing, preferably the first-time upsetting and drawing treatment is performed to obtain a flat square, and the second-time upsetting and drawing treatment is performed in the order of flat square upsetting - axial upsetting - axial drawing - pressing the flat square;

[0065] S3: The slab is subjected to a first heat forging and recrystallization annealing at the same time;

[0066] S4: The flat billet is widened and lengthened, and after machining, a large-size forged plate of target size is obtained.

[0067] In some preferred embodiments of the present invention, a method for preparing a large-size forged plate of TC32 titanium alloy comprises the following steps:

[0068] S1: Heat the titanium alloy ingot that has passed the composition inspection to between 1000℃ and 1200℃, and perform two-fire forging. The number of upsetting and drawing on the ingot flow line in each fire is no more than three upsetting and three drawing. The single upsetting deformation is 35~55%, the pressing amount of each hammer is 20~50 mm, and the pressing rate is 10~40 mm / s. The final forging temperature is not less than 800℃, and the surface is ground after air cooling to obtain the forged billet after opening;

[0069] S2: The forging blank described in step S1 is heated to 15°C to 50°C below the phase transformation point, and subjected to two-time repeated upsetting forging, with a single upsetting deformation of 40% to 60% on the forging blank flow line, a reduction of 20 to 40 mm per hammer, and a reduction rate of 15 to 30 mm / s. The final forging temperature is not less than 800°C, and the surface is ground after air cooling to obtain a flat blank;

[0070] In the two-fire repeated forging, it is preferred that the first fire forging process is used to obtain a flat square, and the second fire forging process is carried out in the order of roughening the flat square - axial roughening - axial drawing - pressing the flat square;

[0071] S3: heating the slab described in step S2 to 15°C to 35°C above the phase transformation point, performing a single-time upsetting forging, wherein the single upsetting deformation is 20% to 35%, and the final forging temperature is not less than 800°C, and then directly placing the slab into a heating furnace for recrystallization annealing treatment, and performing surface grinding treatment after water cooling to obtain a slab;

[0072] S4: The slab described in step S3 is heated to 20°C to 50°C below the phase transformation point, and is subjected to multiple forging fires for widening and lengthening. The final forging temperature is not less than 800°C. After the lengthening and shaping is completed, air cooling is performed, and a large-size forged plate of a target size is obtained after machining.

[0073] The present invention also provides a large-size forged plate of TC32 titanium alloy prepared by the above-mentioned preparation method.

[0074] According to tests, the length of the large-size forged plate of TC32 titanium alloy is 2500~3000 mm, the width is 1000~1500 mm, and the thickness is 150~200 mm.

[0075] It can be seen that the technical solution of the present invention solves the technical problems of uniformity of organizational properties and batch stability of large-sized forged plates of TC32 titanium alloy, breaks through the forging technology bottleneck of large-sized forged plates of titanium alloy, and can meet the demand for large-sized integral titanium alloy forgings in the field of aerospace in my country. In addition, the preparation method of large-sized forged plates of TC32 titanium alloy can realize the industrial production of large-sized forged plates of TC32 titanium alloy, and can be used for direct machining of parts or subsequent die forging.

[0076] In order to further illustrate the present invention, the following examples are used to explain it in detail. The titanium alloy ingots used in the following examples of the present invention are generally commercially available products. m Tensile strength (MPa), R p0.2 It specifies the elongation strength when the non-proportional elongation is 0.2%, A% is the elongation after fracture, and Z% is the cross-sectional shrinkage. m , R p0.2 , A% and Z% are obtained by referring to GB / T 228.1.

[0077] Example 1

[0078] This embodiment prepares a large-sized forging billet with a size of 160×1200×2500 mm, which specifically includes the following steps:

[0079] Step 1: The titanium alloy ingot that has passed the composition inspection is subjected to two-stage pier forging, wherein the heating temperature of the first pier forging is 1150°C, and three piers and three draws are completed, and the single pier roughing deformation is 50%, the pressing amount of each hammer is 30 mm, the pressing rate is 25 mm / s, and the terminal temperature is 840°C; the heating temperature of the second pier forging is 1100°C, and two piers and two draws are completed, and the single pier roughing deformation is 45%, the pressing amount of each hammer is 35 mm, the pressing rate is 30 mm / s, and the terminal temperature is 850°C. After air cooling, the surface is ground to obtain the forged billet after blanking;

[0080] Step 2: The forging blank obtained in step 1 is subjected to two rounds of repeated upsetting and drawing forging, wherein the heating temperature of the first upsetting and drawing forging is 20°C below the phase transformation point, and two upsetting and two drawing are completed. The single upsetting and roughening deformation on the forging blank flow line is 55%, the pressing amount of each hammer is 20 mm, the pressing rate is 25 mm / s, the final forging temperature is 880°C, and the aspect ratio of the flat square pressed after forging is 2:1; the heating temperature of the second upsetting and drawing forging is 25°C below the phase transformation point, and two upsetting and two drawing are completed. The single upsetting and roughening deformation is 50%, the pressing amount of each hammer is 25 mm, the pressing rate is 25 mm / s, the final forging temperature is 830°C, and the aspect ratio of the flat square pressed after forging is 2.5:1. After air cooling, the surface is ground and treated to obtain a flat blank;

[0081] Step 3: The slab obtained in step 2 is heated to 20°C above the phase transformation point, and subjected to one-time two-stage two-stage forging, with a single-stage roughing deformation of 30% and a final forging temperature of 850°C. The slab is then directly placed in a heating furnace for recrystallization annealing treatment at a temperature of 880°C for 240 min, and then surface grinding treatment is performed after water cooling to obtain a slab;

[0082] Step 4: The flat billet obtained in step 3 is widened and stretched for 5 times, and the heating temperature is 30°C below the phase transformation point. The deformation during widening is 45%, and the deformation during stretching is 50%. The third and fifth fires are hot material return to the furnace, and the last forged flat billet is wrapped with asbestos in the fourth and fifth fires. After machining, a large-size forged plate of TC32 titanium alloy with a size of 160×1200×2500 mm is obtained.

[0083] After heat treatment, the large-size forged TC32 titanium alloy plate prepared in this embodiment has uniform high and low-magnification structures in various parts, and small differences in mechanical properties. Its tensile properties are shown in Table 1 (where 3 specimens are taken from each part).

[0084] Table 1 Room temperature tensile properties of TC32 titanium alloy large size forging plate (160×1200×2500 mm)

[0085]

[0086] Example 2

[0087] This embodiment is to prepare a large-sized forging blank with a size of 180×1000×2600 mm, which specifically includes the following steps:

[0088] Step 1: The titanium alloy ingot that has passed the composition inspection is subjected to two-stage pier forging, wherein the heating temperature of the first pier forging is 1180°C, and two piers and two draws are completed, the single pier roughing deformation is 45%, the pressing amount of each hammer is 35 mm, the pressing rate is 35 mm / s, and the terminal temperature is 870°C; the heating temperature of the second pier forging is 1080°C, and three piers and three draws are completed, the single pier roughing deformation is 40%, the pressing amount of each hammer is 30 mm, the pressing rate is 25 mm / s, and the terminal temperature is 820°C. After air cooling, the surface is ground to obtain the forged billet after opening.

[0089] Step 2: The forging blank obtained in step 1 is subjected to two-time repeated upsetting and drawing forging, wherein the heating temperature of the first upsetting and drawing forging is 35°C below the phase transformation point, three upsetting and three drawing are completed, the single upsetting deformation on the forging billet flow line is 50%, the pressing amount of each hammer is 25 mm, the pressing rate is 25 mm / s, the final forging temperature is 850°C, and the aspect ratio of the flat square pressed after forging is 2.5:1; the heating temperature of the second upsetting and drawing forging is 30°C below the phase transformation point, two upsetting and two drawing are completed, the single upsetting deformation is 45%, the pressing amount of each hammer is 20 mm, the pressing rate is 25 mm / s, the final forging temperature is 840°C, and the aspect ratio of the flat square pressed after forging is 2.8:1. After air cooling, the surface is ground to obtain a flat billet.

[0090] Step 3: The slab obtained in step 2 is heated to 25°C above the phase transformation point, and subjected to one-time two-stage two-stage forging, with a single-stage roughing deformation of 30% and a final forging temperature of 830°C. The slab is then directly placed in a heating furnace for recrystallization annealing treatment at a temperature of 850°C for 210 min, and then surface grinding treatment is performed after water cooling to obtain a slab;

[0091] Step 4: The flat billet obtained in step 3 is widened and elongated for 4 times, and the heating temperature is 25°C below the phase transformation point. The deformation during widening is 40%, and the deformation during elongation is 45%. The third and fourth fires are hot material return to the furnace, and the last forged flat billet part is wrapped with asbestos during the fourth fire. After machining, a large-size forged plate of TC32 titanium alloy with a size of 180×1000×2600mm is obtained.

[0092] After heat treatment, the large-size forged TC32 titanium alloy plate prepared in this embodiment has uniform high and low-magnification structures in various parts, and the difference in mechanical properties is small. Its tensile properties are shown in Table 2.

[0093] Table 2 Room temperature tensile properties of TC32 titanium alloy large size forging plate (180×1000×2600 mm)

[0094]

[0095] Example 3

[0096] This embodiment is to prepare a large-sized forging blank with a size of 200×1100×2400 mm, which specifically includes the following steps:

[0097] Step 1: The titanium alloy ingot that has passed the composition inspection is subjected to two-stage pier forging, wherein the heating temperature of the first pier forging is 1150°C, and a total of three piers and three draws are completed, the single pier roughing deformation is 50%, the pressing amount of each hammer is 25 mm, the pressing rate is 30 mm / s, and the terminal temperature is 890°C; the heating temperature of the second pier forging is 1050°C, and a total of three piers and three draws are completed, the single pier roughing deformation is 40%, the pressing amount of each hammer is 30 mm, the pressing rate is 20 mm / s, and the terminal temperature is 840°C. After air cooling, the surface is ground to obtain the forged billet after opening.

[0098] Step 2: The forging blank obtained in step 1 is subjected to two rounds of repeated upsetting and drawing forging, wherein the heating temperature of the first upsetting and drawing forging is 40°C below the phase transformation point, and two upsetting and two drawing are completed. The single upsetting and roughening deformation on the forging blank flow line is 45%, the pressing amount of each hammer is 20 mm, the pressing rate is 25 mm / s, the final forging temperature is 820°C, and the aspect ratio of the flat square pressed after forging is 2.5:1; the heating temperature of the second upsetting and drawing forging is 35°C below the phase transformation point, and two upsetting and two drawing are completed. The single upsetting and roughening deformation is 50%, the pressing amount of each hammer is 20 mm, the pressing rate is 20 mm / s, the final forging temperature is 810°C, and the aspect ratio of the flat square pressed after forging is 2:1. After air cooling, the surface is ground to obtain a flat blank;

[0099] Step 3: The slab obtained in step 2 is heated to 25°C above the phase transformation point, and subjected to one-time two-stage two-stage forging, with a single-stage roughing deformation of 25% and a final forging temperature of 850°C. The slab is then directly placed in a heating furnace for recrystallization annealing treatment at a temperature of 860°C for 300 min, and then surface grinding treatment is performed after water cooling to obtain a slab;

[0100] Step 4: The flat billet obtained in step 3 is widened and stretched for 4 times, and the heating temperature is 40°C below the phase transformation point. The deformation during widening is 35%, and the deformation during stretching is 45%. The second and fourth fires are hot material return to the furnace, and the last forged flat billet part is wrapped with asbestos during the fourth fire. After machining, a large-size forged plate of TC32 titanium alloy with a size of 200×1100×2400mm is obtained.

[0101] After heat treatment, the large-size forged TC32 titanium alloy plate prepared in this embodiment has uniform high and low-magnification structures in various parts, and the difference in mechanical properties is small. Its tensile properties are shown in Table 3.

[0102] Table 3 Room temperature tensile properties of TC32 titanium alloy large size forging plate (200×1100×2400 mm)

[0103]

[0104] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a large-size forged plate of TC32 titanium alloy, characterized in that: The following steps are involved: S1: repeatedly subjecting the TC32 titanium alloy ingot to a drawing treatment at 1000-1200°C to obtain a forged billet after blanking; S2: performing a first-time drawing treatment and a second-time drawing treatment on the forged billet below the phase transformation point, wherein the first-time drawing treatment obtains a flat square, and the second-time drawing treatment is performed in the order of flat square roughening-axial roughening-axial drawing-pressing the flat square, and a first flat billet is obtained; S3: performing a heat drawing treatment on the first slab above the phase transformation point, and performing a recrystallization annealing treatment on the obtained forging slab to obtain a second slab; S4: The second flat billet is widened and elongated below the phase transformation point to obtain a large-size forged plate of TC32 titanium alloy.

2. The preparation method according to claim 1, characterized in that: The repeated pulling and tucking process in step S1 is two-fire pulling and tucking processes, and the number of pulling and tucking processes in each fire does not exceed three pulls and three tuckings; In each fire-drawing treatment, the single roughing deformation is 35~55%, the reduction of each hammer is 20~50 mm, and the reduction rate is 10~40 mm / s; the final forging temperature is not less than 800℃.

3. The preparation method according to claim 1 or 2, characterized in that: When performing roughening during the repeated upsetting process in step S1, a circular tooling mold with a diameter of not less than 1500 mm is used; During the upsetting process of the repeated upsetting treatment in step S1, the upper hammer anvil presses the blank at a uniform speed.

4. The preparation method according to any one of claims 1 to 3, characterized in that In step S2, after the forging is opened, the forging billet is subjected to a first-stage drawing treatment and a second-stage drawing treatment in sequence at 15°C to 50°C below the phase transformation point; The number of pull-outs in the first fire does not exceed three pull-outs and three pull-outs, and the number of pull-outs in the second fire does not exceed two pull-outs and two pull-outs; In the first and second fire upsetting treatments, the single upsetting deformation is 40-60%, the pressing amount of each hammer is 20-40 mm, and the pressing rate is 15-30 mm / s; the final forging temperature is not less than 800°C.

5. The preparation method according to any one of claims 1 to 4, characterized in that The aspect ratio of the first flat slab is 1.5:1~3:

1.

6. The preparation method according to any one of claims 1 to 5, characterized in that Step S3: performing a one-fire, two-hammer, two-draw treatment at 15°C to 35°C above the phase transformation point; in the said drawing treatment, the single roughening deformation is 20-35%; and the final forging temperature is not less than 800°C; The temperature of the recrystallization annealing treatment is 800-900° C., and the holding time is 180-360 min.

7. The preparation method according to any one of claims 1 to 6, characterized in that In step S4, the second flat slab is subjected to a widening and elongation treatment at 20°C to 50°C below the phase transition point; The forging number of the widening and drawing treatment is 3 to 5 times, wherein the deformation during widening is 30 to 50%, and the deformation during drawing is 40 to 60%; the final forging temperature is not less than 800°C; In the forging process of the widening and lengthening treatment, widening is first completed.

8. The preparation method according to any one of claims 1 to 7, characterized in that In step S4, when the aspect ratio of the second slab is greater than 1.5, the portion of the slab to be forged last is wrapped with asbestos.

9. A large-size forged plate of TC32 titanium alloy prepared by the preparation method according to any one of claims 1 to 8.

10. The TC32 titanium alloy large-size forged plate according to claim 9, characterized in that: Its length is 2500~3000mm, width is 1000~1500 mm, and thickness is 150~200 mm.

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