CN114346137A

CN114346137A - Hot processing preparation method of large-size titanium alloy bar with uniform thin banded structure

Info

Publication number: CN114346137A
Application number: CN202111478959.2A
Authority: CN
Inventors: 刘建荣; 王清江; 赵子博; 朱绍祥; 李文渊; 王磊; 陈志勇
Original assignee: Institute of Metal Research of CAS
Current assignee: Institute of Metal Research of CAS
Priority date: 2021-12-06
Filing date: 2021-12-06
Publication date: 2022-04-15
Anticipated expiration: 2041-12-06
Also published as: CN114346137B

Abstract

The invention belongs to the field of titanium-based material hot processing, and particularly relates to a hot processing preparation method of a large-size titanium alloy bar with a uniform thin banded structure. The method comprises the applicable alloy types, hot working processes, application ranges and other composition elements. By adopting the hot processing technology, the bar blank with the cross section macrostructure of 1-3-grade fuzzy crystals and the longitudinal section macrostructure of uniform and thin banded structures can be obtained. The total deformation heat number of the bar billet hot processing can be controlled within 8 fires, the yield can be improved by more than 10 percent, and the method has the technical advantages of short flow, high efficiency and low cost. The bar prepared by the invention is directly used for preparing the blanks of parts such as frames, beams, columns, shafts and the like with the main bearing direction parallel or nearly parallel to the banded structure after simple hot and cold processing, or used as the forging blank of various types of forgings to form the forging structure with fine and uniform grain size after 2-4-fire thermal deformation, thereby meeting the requirements of high-quality and low-cost titanium alloy forgings in the high-tech fields such as aerospace and the like.

Description

Hot processing preparation method of large-size titanium alloy bar with uniform thin banded structure

Technical Field

The invention belongs to the field of titanium-based material hot processing, and particularly relates to a hot processing preparation method of a large-size titanium alloy bar (the diameter or the equivalent diameter is more than or equal to 150mm) with a uniform thin banded structure.

Background

Titanium alloy has the advantages of high specific strength, corrosion resistance, heat resistance and the like, so the titanium alloy is widely applied to the fields of aviation, aerospace, petroleum, chemical engineering, energy sources, automobiles, medical treatment, sports and leisure and the like. With the development of aviation and aerospace technologies, the demand for high-end titanium materials is increasing. However, the high material and processing cost limit the wide application of titanium alloy, and especially for titanium alloy with high brittleness tendency, the high-efficiency preparation process can directly determine the quality stability, price and application of the titanium alloy, reduce the heat processing times, improve the material yield and simultaneously do not reduce the quality of products, especially semi-finished products (such as bars).

The quality of the semi-finished product and the finished product of the titanium alloy material is mainly embodied in the following aspects: 1) the metallurgical quality of the cast ingot refers to the defects of high and low density inclusions, oxides, nitrides, shrinkage cavities, looseness, macroscopic component segregation, segregation and the like which may appear in the titanium alloy cast ingot and the controlled degree, the higher the controlled degree is, the lower the probability of the defects appears is, and the better the metallurgical quality of the cast ingot is; 2) and controlling the microstructure and the uniformity and consistency thereof. On the premise that the metallurgical quality of the cast ingot meets the requirement, the quality of the finished product or the semi-finished product mainly depends on the control of a target microstructure, the uniformity of the grain size and the difference of the grain shape/size (namely the structural consistency) of different parts. It is generally considered that, on the premise that the microstructure type meets the control requirement, the more uniform the grain size and the more discrete the crystallographic orientation of the grains, the smaller the difference of the microstructures at different parts, and the higher the quality of the finished or semi-finished titanium alloy product.

The reason that the price of the titanium alloy semi-finished product and the finished product is high is mainly reflected in the following aspects: 1) the price of raw materials. The raw materials of the titanium alloy mainly comprise sponge titanium and various types of intermediate alloys, the price of the sponge titanium at home and abroad fluctuates about 80 yuan/kg, the price of the intermediate alloys is several times to dozens of times of the price of the sponge titanium, and the price of the raw materials is dozens of times or even dozens of times of that of common steel; 2) and (4) alloy smelting. The titanium alloy has high activity, O in molten state and air₂、N₂、CO₂The reaction of water vapor and the like is violent, and the titanium alloy smelting can only be finished under the protection of vacuum or inert gas because of the chemical reaction with almost all refractory materials in contact with the water vapor, so that a water-cooled copper crucible or a skull is required to be used as a container, and the smelting is carried out by adopting the methods of induction, vacuum self-consumption, plasma and electron beam, so the smelting cost is high;

3) hot working costs. According to different alloy types and requirements, the hot working times of the existing domestic forged titanium alloy products are between several to more than ten, some products even reach more than twenty, and the products are heated by an electric furnace every time; the surface oxidation during the heating process, the surface grinding after forging and the like have raw material loss and energy power loss, so the cost is further increased; so that the price of the titanium alloy is high for a long time. Among the three factors that affect the cost of titanium alloys, the link that has a large cost compression space is the hot working cost. The heat processing heat number is reduced, the raw material loss is reduced, the qualified rate is improved, the cost can be obviously reduced, and the key for reducing the production cost of the titanium alloy product at the present stage is realized.

In conclusion, the stable and controllable microstructure of the titanium alloy semi-finished product and the finished product and good uniformity and consistency are the premise of quality control, and the reduction of the heat frequency, the improvement of the thermal deformation efficiency, the reduction of the energy and the material loss in the thermal deformation process are important means for reducing the production cost.

The titanium alloy hot working process has more patents, and nearly 20 patents are similar to the invention. Such as:

chinese patent publication No. CN109371268A discloses a high temperature and high heatA preparation method of a titanium alloy bar with stability and high creep resistance comprises the steps of heating a Ti55 titanium alloy ingot to 1150-1200 ℃, and then cogging and forging in a beta phase region by using a rapid forging machine or a hydraulic press; then heating to 1050-1100 deg.C, repeatedly upsetting and drawing out forging by using quick forging machine or hydraulic press, then heating the above-mentioned forged blank material to T_β-100℃～T_β-20℃(T_βIs Ti55 titanium alloy alpha + beta/beta phase transition temperature), repeatedly upsetting, drawing and forging to the required size by a quick forging machine or a hydraulic press to obtain the titanium alloy bar with fuzzy microstructure and uniform microstructure. The greatest difference between the reference example and the hot working process used by the invention is that each hot forging of the reference example adopts the repeated upsetting and drawing processes, so that a macrostructure with fuzzy crystals is obtained, and a uniform banded structure is not obtained due to the repeated upsetting; in addition, the invention requires avoiding the temperature interval of large-area recrystallization in the aspect of forging temperature selection, so that the whole thermal deformation temperature interval below the phase change point moves downwards, and the forging process and the pursuit final effect have obvious difference.

Chinese patent publication No. CN111390081A discloses a preparation process of a TC25G titanium alloy forging with high creep resistance and high fracture toughness, which comprises the steps of heating a TC25G bar blank to 50-30 ℃ below the beta transition temperature for upsetting and shaping to obtain a forging blank; then forming the forging stock at 10-40 ℃ above the phase transformation point, wherein the deformation amount is controlled to be 40-80%; and finally, carrying out solid solution and aging double heat treatment to obtain a forging blank microstructure which is a basket structure. The target product of the comparative example is a disc forging, the final hot forging is completed above a beta transformation point, the target structure is a basket structure, the final hot forging is completed at a temperature of 30-200 ℃ below the beta transformation temperature, and the target structure is a thin ribbon structure, which is obviously different from the hot forging of the last several times of the invention,

chinese patent publication No. CN101104898A discloses a novel high-temperature titanium alloy with high thermal strength and high thermal stability, and provides a hot working process of the alloy, which is characterized in that a "low-high-low" process of heating and forging in an α + β two-phase region, a + β single-phase region, and a + α + β two-phase region is adopted, and the intermediate "β single-phase region heating and forging" process can cause the hot working structure of the previous process to be completely recrystallized, thus being contrary to the original design of the thin ribbon-like structure of the present invention. The reference example also provides a process for preparing the thin bar material by adopting the processes of beta single-phase region heating forging, finish forging and rolling. The product specification, application, deformation mode and metal flow under the conditions of finish forging and rolling are completely different from those of the hydraulic press forging, and the method is not comparable to the production process for preparing large-size bars by adopting a hydraulic press.

Chinese patent publication No. CN104018027A discloses a novel heat-resistant titanium alloy, and a processing and manufacturing method and application thereof, comprising alloy components, smelting, hot working, heat treatment and other composition elements. The alloy can obtain different matching of tensile strength and plasticity, durability and creep strength and thermal stability by combining different hot working and heat treatment processes, and can be used for manufacturing parts such as blades, disc parts and the like at high-temperature parts of advanced aeroengines. The hot working temperature range above the beta transformation point is +20 to +150 ℃, and the deformation heating times are required for 2 to 4 times; the temperature range of the hot working process below the phase transition point is 10-60 ℃, the deformation temperature is gradually reduced along with the increase of the deformation heat number, and the microstructure form is not determined. The hot working process of the invention requires that the deformation temperature below the beta transformation point is selected to avoid the temperature interval of large-area recrystallization of the thermal deformation structure, and the recrystallization and growth of crystal grains are avoided, so that the control of the deformation temperature below the beta transformation point is very critical, and the operation of gradually reducing the deformation temperature along with the increase of the deformation fire number is not suitable for obtaining uniform and fine banded structures.

Chinese patent publication No. CN111235506A discloses a hot working process of TC25G titanium alloy forging, which specifically comprises the following steps: 1) cogging and forging of cast ingot: heating and preserving the heat of the alloy cast ingot, discharging the alloy cast ingot from the furnace for forging, heating the cast ingot to a certain temperature, upsetting, drawing and deforming to obtain a blank after beta-phase region cogging; 2) preparing a forging stock: deforming the blank at 100-20 ℃ below the beta transformation point; then heating to 15-40 ℃ above the beta transformation point, carrying out high-temperature homogenization treatment, and then carrying out deformation; cooling to 100-30 ℃ below the beta transformation point and deforming to the bar material with the target size; 3) die forging forming: die forging the forging stock to form; 4) and (3) heat treatment: and carrying out solid solution and aging double heat treatment to obtain a TC25G titanium alloy forging blank, wherein the obtained TC25G forging structure is a two-state structure. The comparative example is characterized in that a low-high-low process is adopted in the preparation process of the forging stock, namely, after deformation is carried out at the temperature of 100-20 ℃ below a phase transformation point, the forging stock is heated to the temperature of 15-40 ℃ above the phase transformation point, then deformation is carried out after high-temperature homogenization treatment, and then deformation is carried out to a target size at the temperature of 100-30 ℃ below a beta phase transformation point. After the thermal deformation temperature of the invention is below the beta transformation point, the subsequent process has no deformation on the transformation point, thereby avoiding the occurrence of complete recrystallization of deformed grains and further influencing the formation of a thin banded structure and the control of size and shape.

Chinese patent publication No. CN109234554A discloses a method for preparing a high-temperature titanium alloy bar, which comprises heating a prepared Ti60 titanium alloy ingot to 1150-1200 ℃, and cogging and forging in a beta phase region by using a rapid forging machine or a hydraulic press; then heating to 1080-1150 deg.C, repeatedly upsetting and drawing out forging by using quick forging machine or hydraulic press, then heating the above-mentioned forged blank material to T_β-120℃～T_β-30℃(T_βIs Ti60 titanium alloy alpha + beta/beta phase transition temperature) is repeatedly upset, drawn and forged to the required size by a quick forging machine or a hydraulic press, and the titanium alloy bar with fuzzy microstructure and uniform microstructure is obtained. The comparative example has the characteristics that repeated upsetting and drawing are emphasized, and finally the forged structure with fuzzy microstructure and uniform high-power structure is obtained, and is completely different from the technical original purpose and the implementation scheme of the invention for obtaining the thin banded structure bar by unidirectional drawing deformation at the phase transformation point.

Chinese patent publication No. CN101967581A discloses a titanium alloy with a fine lamella microstructure and a manufacturing method thereof, which is characterized in that: 1) based on the specific alloy composition; 2) the thermal deformation temperature is selected below the silicide dissolution temperature but not the beta phase transformation point, so that the silicide which can block the growth of crystal grains is ensured to exist in the thermal deformation process; 3) the thin slice lamellar structure with the original beta grain size of below 300 mu m is obtained by heat treatment above the beta transformation point and below the silicide dissolution temperature. Completely different from the thin ribbon target tissue and control method sought by the present invention.

Chinese patent publication No. CN109252061A discloses a preparation method of a titanium alloy bar with high temperature, high thermal stability and high fracture toughness. Heating a TC25G titanium alloy ingot to 1100-1200 ℃, and then cogging and forging in a beta phase region by using a rapid forging machine or a hydraulic press; then heating to 1030-1100 deg.C, repeatedly upsetting and drawing out forging by using quick forging machine or hydraulic press, then heating the above-mentioned forged blank material to T_β-110℃～T_β-20℃(T_βAlpha + beta/beta phase transition temperature of TC25G titanium alloy) is repeatedly upset and drawn by a rapid forging machine or a hydraulic press, and finally the forged blank is heated to T_β-110℃～T_βAnd (4) drawing to a required size by using a rapid forging machine or a hydraulic press at the temperature of minus 30 ℃ to obtain the titanium alloy bar with fuzzy microstructure and uniform high-power microstructure. The comparative example is characterized in that the bar with fuzzy macrostructure and uniform macrostructure is obtained by repeatedly upsetting and drawing in the upper and lower specific temperature ranges of the phase transformation point. Since the microstructure control target is completely different from the fine ribbon structure directed by the present invention, the corresponding control means, process path and deformation mode have significant differences.

Chinese patent publication No. CN111318581A discloses a manufacturing method of a basket structure titanium alloy large-size ring piece, which is characterized in that a titanium alloy blank is subjected to upsetting, punching and shaping at a temperature of 20-50 ℃ below a beta transformation point to obtain a ring blank; reaming the ring blank at the temperature of 20-50 ℃ below the phase transformation point; ring rolling the ring blank after hole expansion at a temperature of 25-80 ℃ above the phase transformation point to form; and finally, carrying out solid solution and aging double heat treatment to obtain the titanium alloy ring piece with the basket structure characteristic. The comparative example is characterized in that the blank is manufactured under the phase transformation point, the deformation is above the phase transformation point in the final stage, the aim is to obtain the rolling ring with the basket structure, the deformation is below the phase transformation point in the final stage, and the aim is to obtain the bar with the thin band-shaped structure and related products are completely different.

Chinese patent publication No. CN111235505A discloses a preparation process of a high-strength and high-toughness TC25G titanium alloy ring, which comprises the following specific steps: 1) cogging: and heating the alloy ingot to a certain temperature for upsetting-drawing forging, and then heating the ingot to a temperature which is 10-50 ℃ above the beta phase transformation point for deformation to obtain a blank after cogging in a beta phase region. 2) Preparing a forging stock: fully deforming the blank at the temperature of 100-20 ℃ below the beta transformation point, and then heating to the temperature of 10-40 ℃ above the beta transformation point for high-temperature homogenization treatment; and fully deforming at 100-30 ℃ below the beta transformation point to obtain a forged blank. 3) Preparing a ring blank: punching and reaming at 60-35 ℃ below the beta transition temperature; 4) ring rolling and forming: rolling and forming to size at 60-35 ℃ below the transformation point; 5) and (3) heat treatment: the ring piece is subjected to solid solution and aging heat treatment through an alpha + beta two-phase region. The TC25G titanium alloy ring piece prepared by the process is in a two-state structure. The obvious characteristic of this comparison example is that after cogging above the beta transformation point, ring-making process of thermal deformation under the transformation point, homogenization heat treatment on the transformation point, thermal deformation under the transformation point, alpha + beta two-phase region solid solution and aging heat treatment is executed, and the target structure is a two-state structure. This is contrary to the object of the present invention of a thin ribbon-like structure, since the homogenization heat treatment at the phase transformation point causes complete recrystallization of the thermally deformed structure.

Chinese patent publication No. CN106947887A discloses a method for preparing a high-temperature titanium alloy forging stock, which comprises the following components in percentage by mass: al: 6.5-7.5%, Sn: 2-3%, Zr: 6-9%, Mo: 0.2-1%, W: 0.5 to 1.4%, Nb: 0.5 to 1.5%, Si: 0.2-0.3%, Er: 0.1-0.3% and the balance Ti; the method is characterized by comprising the following steps of: cutting an alloy ingot into forging blanks with the sizes of a mm multiplied by b mm, wherein b/a is 1.5-2.5, spraying anti-oxidation coatings, performing multidirectional die forging in three vertical directions, keeping the processed ingot in a heat treatment furnace at the temperature of 20-50 ℃ above a phase transition point for a min-b min, taking out the ingot, putting the ingot into a heated die for forging, heating the die to the forging temperature before each forging, putting the forging blanks with the sizes of a mm multiplied by a mm downwards each time, putting the forging blanks into a top die after the placement, and forging the forging blanks into the sizes of a mm multiplied by b mm again at the deformation rate of 0.01-0.03 s < -1 >; after each die forging, the alloy is heated to 20-50 ℃ above the transformation point, and is subjected to heat preservation (a-b)/2 min tempering treatment, and three vertical directions are sequentially forged. The comparative example is characterized by multidirectional forging, namely deformation operations are alternately performed in three perpendicular directions of x, y and z, while the deformation mode of the invention has obvious difference along one direction of x, y or z.

Chinese patent publication No. CN104762576A discloses a preparation method of TC18 titanium alloy full mesh basket medium-sized ultra-long bar, which is characterized in that: 1) cogging and forging the cast ingot at 900-1150 ℃, wherein the forging ratio is 5.6-8.4, and obtaining a primary forging stock; 2) cutting and blanking the primary forging stock in the step one, and then performing (T)_β-50)℃～(T_βUpsetting and drawing forging for 2-3 times at-15) DEG C, wherein the forging ratio per heat is 5.6-7.5, and obtaining an intermediate forging stock; t is_βBeta phase transition temperature in units of; 3) the intermediate forging stock is (T)_β-50)℃～(T_βCarrying out one-time fire precision forging at the temperature of minus 20) ℃ to obtain a precision forging bar; 4) carrying out beta-zone high-temperature solution treatment on the finish-forged bar at the temperature of (T)_β+5)℃～(T_β+50) DEG C, and keeping the temperature for 0.5 to 2 hours; 5) preserving the temperature of the precision forging bar subjected to the solution treatment in the beta region within the range of 300-450 ℃ for 6-24 h, and then air cooling; 6) the method comprises the following steps of (T) placing the precision forging bar in a heating furnace, wherein the precision forging bar is subjected to shape heating treatment in an alpha + beta region after low-temperature aging pretreatment_β-40)℃～(T_βKeeping the temperature within the range of minus 10) DEG C for 1h to 3h, then cooling to 720 ℃ to 760 ℃ along with the furnace, keeping the temperature for 1h to 3h, drawing out and deforming with a small deformation amount of 1 percent to 5 percent after discharging the steel bar out of the furnace to obtain the steel bar with the structure characteristics of the full mesh basket, wherein the diameter is between 50mm and 90mm, and the length is between 2700mm and 3800 mm. It can be seen that, compared with the process of the invention, the diameter of the bar material is smaller, the target structure is a basket structure, the steps of cogging, upsetting-drawing forging, finish forging, high-temperature solution treatment in a beta phase region, low-temperature aging pretreatment, small-deformation drawing deformation and the like are adopted, and the deformation process, the target structure, the bar material specification and the like are obviously different from the process of the invention.

Chinese patent publication No. CN106734796A discloses a forging method of a high-temperature resistant titanium alloy large-size bar for an engine, which is implemented according to the following steps: firstly, carrying out three-fire cogging forging on an ingot, carrying out drawing deformation on the ingot by the first fire, wherein the heating temperature is 1150-1250 ℃, the heat preservation time is 8-10 hours, and the forging ratio is controlled to be 1.4-1.6; the second and third heating times are upsetting and drawing deformation, the heating temperature of the second heating time is 1090-1110 ℃, the heating temperature of the third heating time is 1070-1090 ℃, the heating and heat preservation are carried out for 6-8 hours, the upsetting-drawing forging ratio is controlled to be 2.2-3.2, and water quenching is adopted after forging; secondly, multiple-fire isothermal forging modification is carried out on the cast ingot after the blank opening forging in a two-phase region, the structure of the blank is further refined and homogenized, and air cooling is adopted after forging; thirdly, heating the forging stock at the temperature of 60-80 ℃ below the transformation point, throwing the forging stock into a circle, and performing air cooling after forging to obtain the WSTi64311SC titanium alloy bar. The important role of 3 times of fire of cogging forging is emphasized in the comparison example, deformation dead zones and non-uniform deformation are avoided by adopting the reverse eight-direction treatment, and cracking is avoided by adopting an asbestos coating material. The multiple-fire isothermal forging in the two-phase region adopts an upsetting and drawing process (claim 2), which is completely different from the single-direction drawing process under specific conditions in the invention aiming at obtaining the deformation mode and effect of the thin banded structure.

The Chinese patent publication No. CN105734339A discloses a high-temperature resistant titanium alloy bar and a preparation method thereof, the bar is prepared by a three-one upsetting deformation method, and the uniform and consistent thin strip-shaped structure cannot be obtained because the upsetting deformation is adopted in the whole process.

Chinese patent publication No. CN106862451A discloses a titanium alloy temperature-changing and speed-controlling forging method, which ensures that the blank can generate dynamic recrystallization during each thermal deformation by comprehensively matching and controlling the temperature, deformation rate and deformation amount of high temperature, high speed, large deformation, low temperature, low speed and small deformation under the temperature-changing condition in the free forging process of a large forging blank, and simultaneously realizes the deformation uniformity of the core, the edge and the multi-direction of a large thick section and the enough deformation energy of deformed grains to generate recrystallization and grain growth by controlling the deformation amount per hammer and the total deformation amount per thermal deformation, thereby realizing the purposes of the tissue uniformity and the tissue refinement of the large thick section blank. The comparison scheme utilizes that deformed grains have enough deformation to generate recrystallization and grain growth to realize the purpose of realizing the structural uniformity and the structural refinement of the large thick-section blank, and the invention needs to avoid the consequences of damaging the uniformity and the continuity of a strip-shaped structure due to the large-range recrystallization and grain growth of the deformed structure, so the comparison scheme is completely opposite to the process principle of the invention and is also south-beam northern-frog in specific operation.

Chinese patent publication No. CN106903249A discloses a forging method of a titanium alloy cake with high tissue uniformity, which comprises the steps of carrying out high-temperature homogenization treatment on a titanium alloy ingot, and carrying out upsetting-drawing forging for 1 fire time after the homogenization treatment is finished; and then performing upsetting forging above the beta-phase transition temperature and below the beta-phase transition temperature, performing water cooling after forging, and finally performing upsetting forging forming on the blank for 2-3 times of fire below the beta-phase transition temperature by 30-50 ℃ to obtain a cake with the diameter of 400-700 mm and the thickness of 100-200 mm. The method adopts the means of high-temperature homogenization treatment, water cooling after forging, reversing upsetting and drawing, diagonal drawing and the like to be matched with each other, and designs a reasonable heating and heat-preserving coefficient to ensure the uniformity of the blank to the maximum extent; and a two-phase region high-low-high forging process with the beta phase transition temperature of 30-50 ℃→ 50-70 → 30-50 ℃ is adopted, so that the problem that a single display signal is easy to appear in finished product flaw detection can be obviously improved. Compared with the present invention, the most important characteristics of the comparison example are that upsetting-drawing forging, two-phase region 'high-low-high' forging process, reversing upsetting-drawing, diagonal drawing and other means are adopted, and the method is completely different from the technical principle of only unidirectional drawing of south-beam northern tracks below the beta phase transition temperature of the present invention, and the starting point and the process path are completely different.

Chinese patent publication No. CN106180251A discloses a preparation method of a TC20 titanium alloy fine-grain bar, which is characterized in that the bar is heated at a high temperature below a phase transition point, and one-fire-time multi-pass precision forging is adopted; heating the blank subjected to the finish forging in the step 1 below a phase change point, and carrying out single-fire multi-pass rolling; finally, the fine-grained titanium alloy bar is subjected to heat treatment, straightening and polishing to obtain the TC20 titanium alloy fine-grained bar. The method can produce the fine crystal TC20 bar with the uniform transverse tissue of phi 8-phi 15 mm. The comparative example is that the precision forging and rolling process is adopted to produce the wire rod with the diameter phi of 8-15 mm, and the product specification, the deformation mode, the pass deformation and the deformation efficiency of the wire rod are not comparable to the process of preparing the rod with the diameter phi of 150mm by adopting a hydraulic press or a rapid forging machine.

Chinese patent publication No. CN110508731A discloses a forging method for improving the structure uniformity of a TC4 titanium alloy large-size forging, which comprises the steps of selecting an ingot, peeling off the ingot, cutting off a dead head, and testing the phase transition temperature; adding the treated cast ingotHeat to T_β+/-50-150 ℃ to finish two-to-three-fire forging; then at a temperature T_βFinish forging by one to two fire when the temperature is 20-30 ℃; then at a temperature T_βCompleting a fire at 30-50 ℃; then at a temperature T_βForging with three to four fire at the temperature of (30 to 50) DEG C; then T_βMolding and forging at the temperature of minus 40 to 50 ℃. It is characterized in that_βThe following thermal deformation intermediate process increases the heat number T_βForging at the temperature of 30-50 ℃, reducing the difference of structures of the forge piece from the surface to the inside, homogenizing the structures, and combining the processes of low-high-low, wherein the high fire in the middle can completely recrystallize the deformed structures, and the process is similar to the T-shaped process_βThe following deformation is completely different from the starting point, the process strategy and the path until the bar with the thin banded structure is formed.

Chinese patent publication No. CN108262435A discloses a method for drawing and forging a titanium alloy bar blank, which comprises the following steps: determining the feeding size L of each drawing length; drawing and forging for the first time; feeding a titanium alloy bar blank; performing rotary forging according to the forging method described in the step 1.2 until the deformation of the titanium alloy bar blank with the length of L reaches A; and (4) repeating the step 1.3 to the step 1.4 until the deformation of the whole titanium alloy bar blank reaches A. The comparative example provides a special method for drawing and forging the titanium alloy bar blank, which enhances the deformation controllability, ensures the consistency of the deformation of the end part and the middle part of the bar blank, improves the process stability and is irrelevant to the deformation temperature. The invention adopts a method of cogging forging on a phase change point and drawing-out forging under the phase change point, and the forging heating temperature under the phase change point is selected to avoid a large-area recrystallization and a temperature interval with large recrystallized grains, so as to obtain the titanium alloy bar with the characteristic of thin and strip-shaped structures.

Disclosure of Invention

The invention aims to provide a hot processing preparation method of a large-size titanium alloy bar with a uniform thin banded structure, and the technical principle is suitable for most titanium alloys and Ti₂AlNb and the like. The method is characterized in that: 1) one-time breaking of coarse columnar grains in titanium alloy ingot by thermal deformation above beta transformation pointCrushing, and preparing a blank with a specific specification according to the specification of a finished bar and the control requirement of the total deformation below a beta transformation point; 2) performing unidirectional drawing thermal deformation below a beta transformation point to obtain a thin banded structure with the width less than or equal to 300 mu m; 3) in order to control the size and the shape of the banded structure, the heating temperature below the beta transformation point needs to be selected to meet the basic condition that large-area recrystallization does not occur in the heating and thermal deformation processes; 4) the macrostructures of the cross section and the longitudinal section of the finished bar are respectively a fuzzy structure and a thin band structure, but the macrostructures are observed as uniform structures in any direction of the cross section and the longitudinal section; 5) the bar produced by the process has a certain degree of anisotropy, and can be directly used for preparing parts with main stress directions parallel or approximately parallel to the thin banded structure after simple processing; 6) the bar produced by the process can also be used as a forging blank of a disc forging and a ring forging; 7) simple process, easy operation, short flow, low loss and low cost.

The technical scheme of the invention is as follows:

a hot working preparation method of a large-size titanium alloy bar with a uniform thin banded structure comprises the following steps of finishing thermal deformation in two characteristic temperature ranges above and below a beta phase transition point; when the deformation is below the beta transformation point, the heating temperature is selected to avoid the temperature interval of the deformation tissue for full recrystallization, the deformation mode is unidirectional drawing and the requirement of the minimum deformation is ensured; according to the conversion of the area of the cross section, the diameter or equivalent diameter of the bar prepared by the method is more than or equal to 150mm, the macrostructure of the cross section is 1-3-grade fuzzy crystal, the macrostructure of the longitudinal section is a thin banded structure, the average width of the banded structure is less than or equal to 300 mu m, and the inside of the banded structure is equiaxial, rod-shaped or elongated alpha particles and residual beta phase.

The hot processing preparation method of the large-size titanium alloy bar with the uniform thin banded structure comprises the following steps of firstly, cogging the titanium alloy bar at a temperature of more than a beta transformation point and 100-200 ℃, and forging the titanium alloy bar at a temperature of more than the beta transformation point and 20-100 ℃ for 1-3 fire; then the steel is shifted to 30-100 ℃ below the phase transformation point for single-way drawing, the drawing deformation per fire is more than or equal to 35 percent, and the sum of the deformation under the phase transformation point is more than or equal to 160 percent; the forging equipment adopts a hydraulic press or an oil press or a quick forging machine, and the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

The hot processing preparation method of the large-size titanium alloy bar with the uniform thin banded structure comprises the following steps of firstly, cogging the titanium alloy bar at a temperature of 120-200 ℃ above a beta transformation point, and forging the titanium alloy bar at a temperature of 20-100 ℃ above the beta transformation point for 2 times; then the steel is shifted to 30-100 ℃ below the phase transformation point for single-way drawing, the drawing deformation per fire is more than or equal to 35 percent, and the sum of the deformation under the phase transformation point is more than or equal to 160 percent; the forging equipment adopts a hydraulic press or an oil press or a quick forging machine, and the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

The hot working preparation method of the large-size titanium alloy bar with the uniform thin banded structure comprises the following steps of firstly, cogging the titanium alloy bar at a temperature of 140-200 ℃ above a beta transformation point, and forging the titanium alloy bar at a temperature of 20-100 ℃ above the beta transformation point for 1 heating; then the steel is shifted to 40-100 ℃ below the phase transformation point for single-way drawing, the drawing deformation per fire is more than or equal to 35 percent, and the sum of the deformation under the phase transformation point is more than or equal to 160 percent; the forging equipment adopts a hydraulic press or an oil press or a quick forging machine, and the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

Firstly, forging deformation of the titanium alloy bar at a temperature of 140-200 ℃ above a beta transformation point by at least one upsetting-one drawing is carried out on the titanium alloy bar; then the steel is shifted to 30-100 ℃ below the phase transformation point for single-way drawing, the drawing deformation per fire is more than or equal to 35 percent, and the sum of the deformation under the phase transformation point is more than or equal to 160 percent; the forging equipment adopts a hydraulic press or an oil press or a quick forging machine, and the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

According to the hot processing preparation method of the large-size titanium alloy bar with the uniform thin banded structure, the titanium alloy bar is divided into a plurality of sections, deformation operation perpendicular to the banded structure is applied within the range of 30-100 ℃ below a phase change point, the section and/or the axial shape of the titanium alloy bar is changed, and a frame, beam, column or shaft part blank with linear characteristics is prepared; the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

According to the hot processing preparation method of the large-size titanium alloy bar with the uniform thin banded structure, the deformation operation is flattening or bending, the section is circular or square, and the axial shape is a straight line or a curve.

According to the hot processing preparation method of the large-size titanium alloy bar with the uniform thin banded structure, the titanium alloy bar is divided into a plurality of sections, and alternating thermal deformation parallel to and perpendicular to the banded structure is applied within the range of 30-100 ℃ below a phase transition point and is performed for 2-5 times of fire, so that a disc part blank with a plane characteristic is obtained; the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

According to the hot processing preparation method of the large-size titanium alloy bar with the uniform thin banded structure, the titanium alloy bar is divided into a plurality of sections, flattening, punching, reaming or ring rolling operations which are parallel or vertical to the banded structure are applied within the range of 30-100 ℃ below a phase transition point, and ring part blanks are prepared after 2-5 times of deformation fire; the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

The design idea of the invention is as follows:

the invention provides a hot processing preparation method of a large-size titanium alloy bar with a thin banded structure by taking two key control elements as main grippers. By adopting a special control process, a thin banded structure parallel to the length direction of the bar stock is obtained. The bar material has simple preparation process, short flow, small material loss in the hot working process, good microstructure uniformity and consistency along the length direction, has good mechanical property matching with the direction parallel to the thin banded structure, and can be used for manufacturing parts such as frames, beams, shafts, columns and the like with main stress directions parallel to the thin banded structure after simple processing; the high-quality forged piece or ring rolled piece can be obtained by performing 2-5 times of alternating thermal deformation in a parallel-vertical strip direction on the raw materials of a disc forged piece and a ring rolled piece.

In a word, the forging of the high-temperature titanium alloy at home and abroad mainly controls parameters such as heating temperature, deformation, strain rate, deformation mode, deformation fire frequency and the like, and various specific thermal deformation processes can be formed by different combinations of the factors. Therefore, the core difference of different hot deformation processes is the design concept of the different hot deformation processes, namely 'what product is to be obtained and what technical effect is to be achieved'. The invention relates to a titanium alloy bar with a fine banded structure, which is characterized in that macrostructures of a transverse section and a longitudinal section have large difference but are high-uniformity structures, the provided technical scheme is simple, easy to operate and high in efficiency, the problems of difficult processing, large heat processing times of easily-cracked titanium alloy bars, high microstructure uniformity and consistency control difficulty, high cost and the like of the conventional titanium alloy bar can be effectively solved, and a solution is provided for production and expanded application of high-quality titanium alloy.

The invention has the advantages and beneficial effects that:

1. one of the functions of the hot processing on the beta phase transformation point of the process is to crush the coarse as-cast structure in the cast ingot, the other function is to prepare the forging blank with the specified specification, and the third function is that the alpha phase in the microstructure of the forging blank prepared on the beta phase transformation point is long-strip-shaped, so that the subsequent process is convenient to refine grains and obtain a thin strip-shaped structure.

2. In order to obtain a uniform band-shaped structure, the invention avoids the temperature interval of large-scale recrystallization and obvious growth of beta grains during the hot processing below the beta transformation point, and ensures the uniformity of the band-shaped structure.

3. In order to obtain a uniform thin strip-shaped structure, the invention ensures enough deformation amount when the strip-shaped structure is processed under the beta phase transformation point, so that the uniform average width of the strip-shaped structure is within 300 mu m, and the inside of the strip-shaped structure is a mixed structure consisting of a thin equiaxial alpha, a short rod-shaped alpha, a long strip-shaped alpha and a residual beta phase.

4. The deformation process is simple and the efficiency is high. The invention adopts single drawing deformation instead of upsetting-drawing process in hot working below beta transformation point, and has the advantages of less heat, high efficiency and low cost.

5. The bar with the thin banded structure can be directly used for parts with main stress directions parallel or nearly parallel to the banded structure after being simply processed, such as changing the section shape, bending and the like, and the manufacturing cost of the parts is greatly reduced by utilizing good obdurability matching in the direction parallel to the banded structure.

6. The bar with the fine banded structure can also be used as a disc forging blank to be subjected to alternate thermal deformation in the directions parallel to and perpendicular to the banded structure to prepare a low-cost high-quality stable disc part blank.

7. The bar with the thin banded structure can also be used as a blank of a ring part, and a low-cost ring part blank is prepared by adopting the processes of blank making, punching, hole expanding and ring rolling.

Drawings

FIGS. 1(a) and (b) show a thin ribbon-like macrostructure in a longitudinal section and a blurred macrostructure in a cross section, respectively, of the bar of the present invention.

FIGS. 2(a) and (b) are respectively the forged high power structure insufficiently recrystallized according to the present invention and the high power structure sufficiently recrystallized according to the conventional process.

Detailed Description

In the specific implementation process, the invention provides a hot working preparation method of a large-size titanium alloy bar (the diameter or the equivalent diameter is more than or equal to 150mm) with a uniform thin banded structure, and the method comprises the applicable alloy type, hot working process, application range and other composition elements. The hot working process comprises the components of deformation mode, forging equipment, forging temperature, deformation, strain rate and the like. The hot processing technology comprises the following specific steps:

1) heating the cast ingot at 100-200 ℃ above the beta transformation point, forging for 1 time by using a hydraulic press or an oil press, wherein the nominal deformation is not less than 60%, and cooling in air after forging;

2) heating the forged blank at 20-150 ℃ above the beta transformation point, forging for 1-3 times by using a hydraulic press or an oil press, wherein the nominal deformation of each time is not less than 60%, and cooling in air after forging;

3) before the last thermal deformation above the beta transformation point is finished, calculating the section size of the blank according to the diameter of the finished bar and the deformation requirement below the beta transformation point, and finishing the preparation of the qualified forged blank;

4) single elongation deformation of alpha + beta two-phase region. Heating at 30-100 ℃ below the alpha + beta/beta transformation point, wherein the nominal deformation amount of each fire is not less than 35%, performing hot working by adopting a hydraulic press or a quick forging machine, and performing air cooling after forging;

5) repeating the operation of 4) until the size of the bar stock is close to the control size; in the final stage, the surface is drawn out to the diameter of a finished bar material by small deformation until the diameter is plus 10-30 mm, and the surface is polished after the bar material is cooled to room temperature in air;

6) finally, 1-2 fire forging can be carried out, namely, a finish forging machine is adopted to forge the steel plate to be close to a finished product, and the surface of the steel plate is polished after the steel plate is cooled to room temperature in air;

7) the bar stock prepared by the steps 1) to 6) can be divided into a plurality of sections, the bar stock is heated at the temperature of 30-100 ℃ below an alpha + beta/beta phase transformation point, operations such as flattening, bending and the like which are vertical to a banded structure are applied, the section and/or the axial shape (straight line or curve) of the bar stock are changed, and a blank of a part such as a frame, a beam, a column, a shaft and the like with linear characteristics is prepared;

8) the bar stock prepared by the steps 1) to 6) can be divided into a plurality of sections, and alternating thermal deformation parallel to and perpendicular to the banded structure is applied within the range of 30-100 ℃ below the phase change point, and the deformation fire is carried out for 2-5 times, so as to prepare a plate part blank with a plane characteristic;

9) the bar stock prepared by the steps 1) to 6) can be divided into a plurality of sections, flattening, punching, reaming, ring rolling and other operations which are parallel to or vertical to the banded structure are applied within the range of 30-100 ℃ below the phase transition point, and ring part blanks are prepared by deforming and heating for 2-5 times.

Wherein, the strain rate control should avoid the local temperature rise in the forging blank to exceed 20 ℃, and the upper limit of the deformation rate control can be determined through deformation simulation. By adopting the hot processing technology, the rod blank with the cross section macrostructure of 1-3-grade fuzzy crystals (graded according to GJB 2220A-2018) and the longitudinal section macrostructure of uniform and thin banded structures can be obtained. The total deformation heat number of the bar billet hot processing can be controlled within 8 fires, the yield can be improved by more than 10 percent, and the method has the technical advantages of short flow, high efficiency and low cost. The bar prepared by the technology can be directly used for preparing blanks of parts such as frames, beams, columns, shafts and the like with main bearing directions parallel or nearly parallel to the banded structures after simple hot and cold processing, can also be used as forging blanks of various types of forgings, forms forging structures with fine and uniform grain sizes after thermal deformation of 2-4 fire, and meets the requirements of high-quality and low-cost titanium alloy forgings in the high-technology fields such as aerospace and the like.

The present invention will be explained in further detail below by way of examples and figures.

Example 1

Smelting the alloy ingot with the diameter of 710mm for 3 times by adopting a vacuum consumable electrode arc furnace, wherein the component is Al 5.8 wt.%; sn 4.0 wt.%; zr 3.5 wt.%; mo 0.5wt%; si 0.40 wt.%; nb 0.3 wt.%; ta 1.0 wt.%; w0.8 wt.%; c0.05 wt.%; fe ≤ 0.05 wt.%; o is less than or equal to 0.15 wt.% and the balance is Ti (alloy mark is Ti65), and the phase transformation point (T) is measured by a metallographic method_β) The temperature was 1040 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: 1 st heating, wherein the heating temperature is 1200 ℃, the hydraulic press is used for upsetting and drawing out or drawing out and upsetting, a circle with the diameter of 720mm → an octagon with the opposite side distance of 720mm, and the nominal deformation of upsetting or drawing out is more than or equal to 40 percent; heating to 1120 ℃ at the 2 nd heating temperature, performing upsetting-drawing-upsetting operation on the octagon with the opposite side distance of 720mm to obtain the octagon with the opposite side distance of 1160mm, wherein the upsetting or drawing nominal deformation is more than or equal to 40%; heating at 1060 deg.C under the condition of fire number 3, drawing out and upsetting with hydraulic press to obtain octagon or square with side distance of 1260mm, and upsetting or drawing out nominal deformation of 40%; heating at 990 ℃ by a fire No. 4, drawing out by a hydraulic press, wherein the distance between opposite sides of the octagon or the square is 1260mm → the distance between opposite sides of the octagon or the square is 900mm, and the deformation is 49%; heating at 990 ℃ by using a 5 th fire, drawing out the hydraulic press, and performing octagonal or square shape with the distance between opposite sides of 900mm → octagonal or square shape with the distance between opposite sides of 700mm, wherein the deformation amount is 40%; heating at 990 ℃ by a 6 th fire, drawing out by a hydraulic press, wherein the distance between opposite sides of the octagon or the square is 700mm → the distance between opposite sides of the octagon or the square is 540mm, and the nominal deformation of drawing out is 40%; heating at 990 ℃ on the 7 th fire, drawing out by a hydraulic press, and drawing out an octagon or a square → a phi 420mm circle with the distance between opposite sides of 540mm, wherein the deformation is 40%; after cooling, machining and peeling

Considering the surface temperature drop in the deformation process, the finish forging temperature per fire is controlled to be T_βAt-200 ℃ that is 840 ℃.

Description of the drawings: in the embodiment of the invention, the specification of the forged blank is divided into three specifications of a circle blank and an octagon blank or a square blank, and the specification of the round blank is used

The section size of the octagonal or square blank is uniformly expressed by the distance between any two opposite sides; the calculation formula of upsetting deformation is delta-Delta L/L₀The calculation formula of the elongation deformation is delta-Delta L/L₁Where Δ L is the stock length L before deformation₀And length L of deformed blank₁The difference between the two; the cross section of the final bar can be round, square or rectangular, and the shape of the cross section of the bar does not substantially influence the thin strip-shaped tissue characteristics and the deformation process. The heating mode is resistance furnace heating, and the temperature control precision is +/-10 ℃; in the following examples, the description applies to all relevant expressions unless otherwise specified.

Example 2

Smelting the alloy ingot with the diameter of 710mm for 3 times by adopting a vacuum consumable electrode arc furnace, wherein the component is Al 5.8 wt.%; sn 4.0 wt.%; zr 3.5 wt.%; mo 0.5 wt.%; si 0.40 wt.%; nb 0.3 wt.%; ta 1.0 wt.%; w0.8 wt.%; c0.05 wt.%; fe ≤ 0.05 wt.%; o is less than or equal to 0.15 wt.% and the balance is Ti (alloy mark is Ti65), and the phase transformation point (T) is measured by a metallographic method_β) The temperature was 1040 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: heating at 1200 ℃ on the 1 st fire, upsetting, lengthening or lengthening and upsetting by a hydraulic press, rounding with phi of 710mm → octagonal with 710mm, wherein the nominal deformation of upsetting or lengthening is more than or equal to 40 percent; heating at the 2 nd fire at the temperature of 1120 ℃, upsetting, lengthening and upsetting by a hydraulic press to obtain a 1200mm octagon, wherein the upsetting or lengthening deformation is more than or equal to 35 percent; heating at 980 ℃ by using a No. 3 fire, drawing out a hydraulic press, wherein the shape of the octagon is 1200mm → the octagon is 880mm or the square is square, and the deformation is 46%; heating at 990 ℃ by using a fire No. 4, drawing out by using a hydraulic press, wherein the deformation of the 880mm octagon or square → 640mm octagon or square is 47%, and the center is divided; heating at 990 ℃ in the 5 th fire, drawing out the 640mm octagon or the square → 480mm octagon by a hydraulic press, wherein the deformation is 44%; heating at 990 ℃ by the fire at the 6 th temperature, drawing out by a hydraulic press, wherein the shape of the octagon of 480mm → the circle of phi 370mm is changed by 40 percent; after cooling, the machine adds the scalping to

Phase transition point (T)_β) The sum of the total deformation of the next 4 times of fire drawing is 177%. Considering the surface temperature drop in the deformation process, the finish forging temperature per fire is controlled to be T_βAt-200 ℃ that is 840 ℃.

Example 3

Smelting by adopting a vacuum consumable electrode arc furnace3 times of obtaining an alloy ingot with the diameter of 710mm, wherein the composition is Al 5.8 wt.%; sn 4.0 wt.%; zr 3.5 wt.%; mo 0.5 wt.%; si 0.40 wt.%; nb 0.3 wt.%; ta 1.0 wt.%; w0.8 wt.%; c0.05 wt.%; fe ≤ 0.05 wt.%; o is less than or equal to 0.15 wt.% and the balance is Ti (alloy mark is Ti65), and the phase transformation point (T) is measured by a metallographic method_β) The temperature was 1040 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: heating at 1200 ℃ under the condition of the 1 st fire, upsetting, lengthening or lengthening and upsetting by a hydraulic press, forming a circle with the diameter of 720mm → an octagon with the opposite side distance of 720mm, wherein the deformation of upsetting or lengthening is more than or equal to 40 percent; heating at 1100 deg.C under the condition of 2 nd fire, upsetting with a hydraulic press, drawing out, upsetting, and upsetting with 720mm octagon → 1160mm octagon or square, wherein the deformation of upsetting and drawing out is more than or equal to 40%; heating at 980 ℃ by using a No. 3 fire, drawing out by using a hydraulic press, and controlling the deformation amount to be 40% in an 1160mm octagonal or square → 880mm octagonal or square shape; heating at 990 ℃ by using a 4 th fire, drawing out by using a hydraulic press, wherein the shape of an octagon or a square shape → 690mm octagon or a square shape is 880mm, and the deformation amount is 40%; heating at 990 ℃ by using a 5 th fire, drawing out by using a hydraulic press, wherein the deformation amount is 40% and the center is divided by 690mm octagon or square → 530mm octagon or square; heating at 990 ℃ by using a 6 th fire, drawing out a hydraulic press to form a 530mm octagon or a square → 410mm octagon, wherein the deformation is 40%; heating at 990 ℃ on the 7 th fire, drawing out by a hydraulic press, wherein the shape of the 410mm octagon → the phi 320mm circle is 40 percent; mechanically peeling after cooling to

Phase transition point (T)_β) The deformation amount of the next 5 times of fire drawing is about 200 percent. Considering the surface temperature drop in the deformation process, the finish forging temperature per fire is controlled to be T_βAt-200 ℃ that is 840 ℃.

Example 4

The 410mm octagonal blank obtained by the fire of the 6 th part in the embodiment 3 is deformed by applying the fire of the 7 th part, the heating temperature is 990 ℃, the drawing length of a hydraulic press is 320mm octagonal blank, and the deformation is 40%; applying 8 th fire for deformation, heating at 980 deg.C, drawing out to form phi 270mm circle with deformation amount of 30%; after cooling, the machine adds the scalping to

Example 5

Smelting the alloy ingot with the diameter of 710mm for 3 times by adopting a vacuum consumable electrode arc furnace, wherein the component is Al 5.8 wt.%; sn 4.0 wt.%; zr 3.5 wt.%; mo 0.5 wt.%; si 0.40 wt.%; nb 0.3 wt.%; ta 1.0 wt.%; w0.8 wt.%; c0.05 wt.%; fe ≤ 0.05 wt.%; o is less than or equal to 0.15 wt.% and the balance is Ti (alloy mark is Ti65), and the phase transformation point (T) is measured by a metallographic method_β) The temperature was 1040 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: heating at the temperature of 1160 ℃ on the 1 st fire, upsetting, lengthening and upsetting by a hydraulic press to obtain an octagon or a square with the thickness of 1030mm, wherein the deformation of upsetting or lengthening is more than or equal to 35 percent; heating at 980 ℃ by using a No. 2 fire, drawing out by using a hydraulic press, and forming an octagon or square shape of 1030mm → an octagon or square shape of 790mm with a deformation of 40%; heating at 990 ℃ by using a3 rd fire, drawing out by using a hydraulic press, and forming a 790mm octagon or square → 610mm octagon or square with the deformation of 40%; heating at 990 ℃ by using a fire No. 4, drawing out by using a hydraulic press, wherein the deformation of the octagon or the square is 610mm → the octagon or the square is 470mm, and the center is divided by 40%; heating at 990 ℃ by using a 5 th fire, drawing out by using a hydraulic press, wherein the deformation amount is 46% in a 470mm octagon or square → 370mm octagon or square shape; heating at 990 ℃ by using a 6 th fire, drawing out by using a hydraulic press, wherein the deformation amount is 40% in an octagon shape of 370mm or a square shape → an octagon shape of 280 mm; heating at 990 ℃ on the 7 th fire, drawing out by a hydraulic press, wherein the shape of the octagon with the thickness of 280mm → the circle with the diameter of 220mm is 40 percent; after cooling, the machine adds the scalping to

Phase transition point (T)_β) The total deformation of the next 6 fire drawing is about 240%. Considering the surface temperature drop in the deformation process, the finish forging temperature per fire is controlled to be T_βAt-200 ℃ that is 840 ℃.

Example 6

Smelting the alloy ingot with the diameter of 610mm for 3 times by adopting a vacuum consumable electrode electric arc furnace, wherein the component is Al 5.8 wt.%; sn 4.0 wt.%; zr 3.5 wt.%; mo 0.5 wt.%; si 0.40 wt.%; nb 0.3 wt.%;ta 1.0 wt.%; w0.8 wt.%; c0.05 wt.%; fe ≤ 0.05 wt.%; o is less than or equal to 0.15 wt.% and the balance is Ti (alloy mark is Ti65), and the phase transformation point (T) is measured by a metallographic method_β) The temperature was 1040 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: 1 st heating, wherein the heating temperature is 1200 ℃, upsetting, stretching and upsetting deformation are carried out by a hydraulic press, and the upsetting or stretching deformation amount is more than or equal to 35% from phi 610mm circle → 790mm octagon or square; heating at 990 ℃ by using a 2 nd fire, drawing out by using a hydraulic press, and forming a 790mm octagon or square → 610mm octagon or square with the deformation of 40%; heating at 990 ℃ in a fire number 3, drawing out the 610mm octagon or square → 470mm octagon or square by a hydraulic press, and deforming by 40%; heating at 990 ℃ by using a fire No. 4, drawing out by using a hydraulic press, wherein the deformation of the 470mm octagon or square → 370mm octagon or square is 40%, and the center is divided; heating at 990 ℃ by using a 5 th fire, drawing out by using a hydraulic press, wherein the deformation amount is 40% in an octagon shape of 370mm or a square shape → an octagon shape of 280 mm; heating at 990 ℃ by fire No. 6, drawing out by a hydraulic press, wherein the shape of the octagon is 280mm → the circle is phi 220mm, and the deformation is 40%; after cooling, the machine adds the scalping to

Example 7

Smelting the alloy ingot with the diameter of 610mm for 3 times by adopting a vacuum consumable electrode electric arc furnace, wherein the component is Al 5.8 wt.%; sn 4.0 wt.%; zr 3.5 wt.%; mo 0.5 wt.%; si 0.40 wt.%; nb 0.3 wt.%; ta 1.0 wt.%; w0.8 wt.%; c0.05 wt.%; fe ≤ 0.05 wt.%; o is less than or equal to 0.15 wt.% and the balance is Ti (alloy mark is Ti65), and the phase transformation point (T) is measured by a metallographic method_β) The temperature was 1040 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: heating at 1200 ℃ on the 1 st fire, upsetting, lengthening or lengthening and upsetting by a hydraulic press, rounding with the diameter of 610mm → octagonal or square with the diameter of 610mm, and upsetting or lengthening deformation of more than or equal to 35 percent; heating at 990 deg.C with fire No. 2, drawing with hydraulic press, and drawing with 610mm octagon or square → 470mm octagonA polygon or square shape, with a deflection of 40%; heating at 990 ℃ in a fire number 3, drawing out by a hydraulic press, wherein the deformation amount is 38% in a 470mm octagon or square → 370mm octagon or square shape; heating at 990 ℃ by using a fire No. 4, drawing out by using a hydraulic press, wherein the deformation is 42% in a 370mm octagon or square → 280mm octagon or square shape, and dividing; heating at 980 ℃ by using a 5 th fire, drawing out a 280mm octagon or a square → 220 mm-phi octagon by using a hydraulic press, wherein the deformation is 40%; heating at 990 ℃ on the 6 th fire, drawing out by a hydraulic press or rolling by a rolling mill, wherein the shape of the 220mm octagon → 160-170 mm of phi is round, and the deformation is 40%. After cooling, the machine adds the scalping to

Example 8

Smelting the alloy ingot with the diameter of 710mm for 3 times by adopting a vacuum consumable electrode arc furnace, wherein the component is Al 5.5 wt.%; sn 3.5 wt.%; zr 3.0 wt.%; mo 0.8 wt.%; si 0.3 wt.%; nb 0.4 wt.%; ta 0.4 wt.%; fe ≤ 0.10 wt.%; o is less than or equal to 0.15 wt.% and the balance is Ti (alloy mark is TA32), and the phase transformation point (T) is measured by a metallographic method_β) Is 1010 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: heating at 1200 ℃ on the 1 st fire, upsetting, stretching and upsetting by a hydraulic press, forming a circle with phi of 710mm → 940mm octagon or square, and upsetting or stretching deformation more than or equal to 40 percent; heating at 960 deg.C under the condition of 2 nd fire, drawing out with hydraulic press, 940mm octagon or square → 700mm octagon or square, and deformation 44%; heating at 970 ℃ on the No. 3 fire, drawing out the 700mm octagon or square → 530mm octagon or square by a hydraulic press, wherein the deformation is 43 percent; heating at 970 ℃ on the 4 th fire, drawing out the octagonal or square shape with the diameter of 530mm → the octagonal or square shape with the diameter of 390mm by a hydraulic press, and dividing by 45 percent of deformation; heating at 960 deg.C with fire 5, drawing out with hydraulic press, with 390mm octagon or square → 290mm octagon, and deformation 44%; heating at 970 ℃ on the 6 th fire, drawing out by a hydraulic press, wherein the shape of the 290mm octagon → the phi 220mm circle is 44 percent; phase transition point (T_β) The sum of the deformation of the drawing is about 220 percent in the next 5 times of fire. Mechanically peeling after cooling to

Example 9

Smelting the alloy ingot with the diameter of 710mm for 3 times by adopting a vacuum consumable electrode arc furnace, wherein the component is Al 5.8 wt.%; sn 4.0 wt.%; zr 3.5 wt.%; mo 0.5 wt.%; si 0.4 wt.%; nb 0.7 wt.%; c0.05 wt.%; fe ≤ 0.015 wt.%; 0.075O 0.15 wt.% and Ti (alloy mark Ti150), and the phase transition point (T) is measured by a metallographic method_β) At 1042 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: 1 st heating, wherein the heating temperature is 1200 ℃, upsetting, stretching and upsetting deformation are applied by a hydraulic press, the diameter is 710mm round → 710mm octagon or square, and the upsetting or stretching deformation amount is more than or equal to 40 percent; heating at 1070 deg.C under the condition of hydraulic press upsetting + stretching + upsetting, and upsetting or stretching deformation of 710mm circle → 900mm octagon or square shape is not less than 40%; heating at 980 ℃ by using a No. 3 fire, drawing out a hydraulic press, wherein the deformation amount is 41 percent, and the shape of the octagon or the square is 900mm → 690 mm; heating at 990 ℃ by using a 4 th fire, drawing out by using a hydraulic press, and forming a 690mm octagon or square → 540mm octagon or square with the deformation of 40%; heating at 990 ℃ by using a 5 th fire, drawing out by using a hydraulic press, wherein the deformation of the octagon or square shape is 540mm → the octagon or square shape is 420mm, and the center is divided by 40%; heating at 980 ℃ with the fire No. 6, drawing out the 420mm octagon or the square → 320mm octagon by a hydraulic press, and deforming by 40%; heating at 990 ℃ on the No. 7 fire, drawing out by a hydraulic press, and forming a 320mm octagon → 250mm circle with the deformation of 40 percent. Mechanically peeling after cooling to

Phase transition point (T)_β) The deformation amount of the next 5 times of fire drawing is about 200 percent.

Example 10

Smelting the alloy ingot with the diameter of 610mm for 3 times by adopting a vacuum consumable electrode electric arc furnace, wherein the component is Al 6.7 wt.%; v1.0 wt.%; zr 2.0 wt.%; mo 1.0 wt.% and the balance Ti (alloy designation TA)15) Phase transition point (T) measured by metallographic method_β) At 980 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: heating at 1180 ℃ on the 1 st fire, upsetting, stretching and upsetting by a hydraulic press, wherein the diameter is 610mm round → 840mm octagon or square, and the deformation of upsetting or stretching is more than or equal to 40%; heating at 935 ℃ in the 2 nd fire, drawing out the 840mm octagon or square → 560mm octagon or square by a hydraulic press, wherein the deformation is 45%; heating at 930 ℃ by using a fire No. 3, drawing out a hydraulic press, wherein the deformation of the 560mm octagon or square → 380mm octagon or square is 45%, and dividing; heating at 930 ℃ by using a fire No. 4, drawing out the octagon or the square with the length of 380mm → the octagon or the square with the length of 250mm by using a hydraulic press, wherein the deformation is 45%; heating at 930 ℃ by using a 5 th fire, drawing out by using a hydraulic press or rolling by using a rolling mill, wherein the shape of the octagon or the square with the diameter of 250mm → the circle with the diameter of 160-170 mm is 45 percent; phase transition point (T)_β) The sum of the deformation of the next 4 times of fire drawing is about 180 percent. After cooling, the machine adds the scalping to

Example 11

Smelting the alloy ingot with the diameter of 710mm for 3 times by adopting a vacuum consumable electrode electric arc furnace, wherein the component is Al 6.0 wt.%; sn 2.0 wt.%; zr 4.0 wt.%; mo 2.0 wt.%; si 0.08 wt.% and the balance Ti (alloy designation TA19), phase transition point (T) as determined by metallographic methods_β) The temperature was 1002 ℃. After removing surface oxide skin and cutting a dead head, preparing a bar stock by the cast ingot according to the following process: heating at 1180 ℃ on the 1 st fire, upsetting, lengthening or lengthening and upsetting by a hydraulic press, wherein the diameter is 710mm round → 1030mm octagonal or square, and the deformation of upsetting or lengthening is more than or equal to 40 percent; heating at 950 ℃ with a 2 nd fire, drawing out the octagonal or square shape of 1030mm → 800mm with the octagonal or square shape of 40% deformation by a hydraulic press; heating at 950 ℃ in a fire number of 3, drawing out the octagon or square shape with the size of 800mm → the octagon or square shape with the size of 600mm and deforming by 43 percent by using a hydraulic press; heating at 960 deg.C with a hydraulic press, drawing out 600mm octagon or square → 400mm octagon or square with a deformation of about 45%, and dividing; heating at 950 deg.C with fire No. 5, drawing out with hydraulic press, 400mm octagon or square → 270mm octagon, and deforming amount45 percent; fire No. 6, heating temperature 950 ℃, drawing out by a hydraulic press, and octagonal shape of 270mm →

Round, deformation 34%. Phase transition point (T)_β) The sum of the deformation of the next 4 times of fire drawing is about 207 percent, and the scalping is added after the cooling

Example 12

Obtained by the methods of examples 1 to 6 and 8 to 11

The round bar stock is cut into blanks with specific lengths as required, then the blanks are heated at the temperature of 30-100 ℃ below a phase transformation point, 2-4 groups of alternate thermal deformation of vertical banded structures and parallel banded structures are applied, and the single deformation of the vertical banded structures and/or the parallel banded structures is more than or equal to 35 percent, so that prefabricated blanks of cake-shaped parts such as discs and the like are obtained; heating at 30-100 deg.c below the phase change point, and isothermal forging, hot die forging or free forging to obtain the part blank.

Example 13

Obtained by the methods of examples 1 to 6 and 8 to 11

The round bar stock is cut into bar stocks with specific lengths according to the requirements, then heated at 30-100 ℃ below the first fire phase transition point, subjected to thermal deformation vertical to the banded structure, flattened on the outer side surface of the circumference, subjected to punching while hot or subjected to furnace returning and heating, and then punched; heating at 30-100 ℃ below the second thermal phase transition point, and reaming or reaming and ring rolling or directly rolling the ring to obtain the annular part blank.

Example 14

Obtained by using examples 7 and/or 10

Cutting round bar into bar blank with specific length, heating at 30-100 deg.C below phase transition point, and applying edge barThe radial deformation of the material or the bending deformation vertical to the banded structure can adjust the deformation amount according to the size of the part blank to obtain rod-shaped blanks with different section shapes; the bar-shaped blank is bent along the length direction by adopting a specific tool to manufacture a part blank with different curvatures of the characteristics of a frame, a beam and a column.

As can be seen from FIG. 1(a), the macrostructure of the longitudinal section of the bar of the present invention shows the characteristic of a thin banded structure along the length direction of the bar, i.e., the microstructure is uniformly elongated into a band along the length direction of the bar, and the width of the banded structure is within 300 μm; as can be seen from the cross-sectional macrostructure of fig. 1(b), since the macrostructure of the longitudinal section is an elongated thin band-like structure, any deformation trace is not seen in the cross section perpendicular to the band-like structure; in addition, because the width of the banded structure is controlled within 300 mu m, the cross-section macrostructure is completely fuzzy crystal, and clear crystal or semi-clear crystal phenomena caused by the existence of coarse crystal or incomplete deformation of the coarse crystal are not found.

FIG. 2(a) is a typical high magnification structure of the bar of the present invention, and it can be seen that the high magnification structure is composed of elongated or equiaxed fine alpha grains and residual beta phase, and no significant recrystallization phenomenon is found in the forged high magnification structure; fig. 2(b) shows a high-power structure of a bar in the conventional process, because of the influences of higher deformation temperature, more deformation heat, lower deformation efficiency, etc., the forged high-power structure is very similar to the heat-treated high-power structure, and is a more typical two-state structure, which indicates that the bar undergoes more obvious recrystallization and grain growth during the deformation process and the cooling process after the deformation.

In conclusion, the invention starts from the high-efficiency connection between the titanium alloy ingot and the finished part blank, simplifies the process, reduces the cost, improves the product quality stability and the like, through the research and analysis on the hot working process and the product application of the titanium alloy which are reported in the application and/or the literature, on the basis of experiment and theoretical exploration, according to the requirements of the fields of aviation, aerospace and the like on low cost and high quality stability of titanium alloy products, a hot processing manufacturing method of a titanium alloy bar with the characteristics of a uniform thin banded structure is provided, a hot processing process is designed by closely surrounding the target of how to obtain the thin banded structure, the purpose of a deformation process above a phase transformation point is to convert the traditional refined columnar crystal structure and the original beta crystal grain into a broken columnar crystal structure, and a forging blank meeting the requirement of the lowest deformation is provided for thermal deformation below the phase transformation point; the deformation characteristic below the phase transition point is simple drawing, the premise of selecting the deformation temperature is that large-area recrystallization does not occur, the obvious growth of crystal grains is avoided, the deformation process is obviously simplified, the process control is simpler, the controllable degree of the quality stability of the bar stock is higher, and the obtained bar stock can be directly used for preparing the bar part blank with the main stress direction parallel or nearly parallel to the banded structure after being simply processed; the material can also be used as an original blank for preparing a cake-shaped forging blank represented by a disc part for aerospace and an annular part blank represented by parts such as a casing, a drum barrel and the like, and has wide application. The hot working manufacturing method of the titanium alloy bar with the uniform and thin banded structure characteristic is suitable for the titanium-based materials which can be hot-worked by the forging and rolling method at present and in the future in technical principle.

Claims

1. A hot working preparation method of a large-size titanium alloy bar with a uniform thin banded structure is characterized in that thermal deformation is completed in two characteristic temperature intervals above and below a beta phase transition point; when the deformation is below the beta transformation point, the heating temperature is selected to avoid the temperature interval of the deformation tissue for full recrystallization, the deformation mode is unidirectional drawing and the requirement of the minimum deformation is ensured; according to the conversion of the area of the cross section, the diameter or equivalent diameter of the bar prepared by the method is more than or equal to 150mm, the macrostructure of the cross section is 1-3-grade fuzzy crystal, the macrostructure of the longitudinal section is a thin banded structure, the average width of the banded structure is less than or equal to 300 mu m, and the inside of the banded structure is equiaxial, rod-shaped or elongated alpha particles and residual beta phase.

2. The hot working preparation method of a large-size titanium alloy bar with a uniform thin banded structure according to claim 1, characterized in that firstly, the titanium alloy bar is cogging at 100-200 ℃ above the beta transformation point and forged at 20-100 ℃ above the beta transformation point for 1-3 fire; then the steel is shifted to 30-100 ℃ below the phase transformation point for single-way drawing, the drawing deformation per fire is more than or equal to 35 percent, and the sum of the deformation under the phase transformation point is more than or equal to 160 percent; the forging equipment adopts a hydraulic press or an oil press or a quick forging machine, and the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

3. The hot working preparation method of a large-size titanium alloy bar with a uniform thin banded structure according to claim 1, characterized in that firstly the titanium alloy bar is cogging at 120-200 ℃ above the beta transformation point and forged for 2 fires at 20-100 ℃ above the beta transformation point; then the steel is shifted to 30-100 ℃ below the phase transformation point for single-way drawing, the drawing deformation per fire is more than or equal to 35 percent, and the sum of the deformation under the phase transformation point is more than or equal to 160 percent; the forging equipment adopts a hydraulic press or an oil press or a quick forging machine, and the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

4. The hot working preparation method of the large-size titanium alloy bar with the uniform thin banded structure as claimed in claim 1, wherein the titanium alloy bar is firstly cogging at 140-200 ℃ above the beta transformation point and forged for 1 fire at 20-100 ℃ above the beta transformation point; then the steel is shifted to 40-100 ℃ below the phase transformation point for single-way drawing, the drawing deformation per fire is more than or equal to 35 percent, and the sum of the deformation under the phase transformation point is more than or equal to 160 percent; the forging equipment adopts a hydraulic press or an oil press or a quick forging machine, and the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

5. The hot working preparation method of the large-size titanium alloy bar with the uniform thin banded structure as claimed in claim 1, wherein firstly, the titanium alloy bar is forged and deformed by not less than one upsetting and one drawing at a temperature of 140-200 ℃ above a beta transformation point; then the steel is shifted to 30-100 ℃ below the phase transformation point for single-way drawing, the drawing deformation per fire is more than or equal to 35 percent, and the sum of the deformation under the phase transformation point is more than or equal to 160 percent; the forging equipment adopts a hydraulic press or an oil press or a quick forging machine, and the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

6. The method for hot working a large-sized titanium alloy bar having a uniform thin ribbon-like structure according to any one of claims 1 to 5, wherein the titanium alloy bar is divided into a plurality of sections, and a deformation operation perpendicular to the ribbon-like structure is applied at a temperature ranging from 30 ℃ to 100 ℃ below the transformation point to change the cross section and/or the axial shape thereof, thereby preparing a frame, beam, column or shaft part blank having a linear characteristic; the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

7. The method for hot working a large-sized titanium alloy bar having a uniform thin ribbon-like structure as recited in claim 6, wherein the deforming operation is flattening or bending, the cross section is circular or square, and the axial shape is a straight line or a curved line.

8. The hot working preparation method of the large-size titanium alloy bar with the uniform thin banded structure according to one of claims 1 to 5, characterized in that the titanium alloy bar is divided into a plurality of sections, and alternating thermal deformation parallel to and perpendicular to the banded structure is applied within the range of 30-100 ℃ below the phase transformation point, and the deformation is carried out for 2-5 times of fire, so as to obtain a disc part blank with a plane characteristic; the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.

9. The hot working preparation method of the large-size titanium alloy bar with the uniform thin banded structure according to one of claims 1 to 5, characterized in that the titanium alloy bar is divided into a plurality of sections, flattening, punching, reaming or ring rolling operations which are parallel or vertical to the banded structure are applied within the range of 30-100 ℃ below the phase transition point, and ring part blanks are prepared by deforming and heating for 2-5 times; the heating equipment adopts a resistance furnace with the temperature control precision of +/-10 ℃.