阅读说明：本技术 用于等温锻造的大型模具坯料的制备方法 (Preparation method of large-scale die blank for isothermal forging ) 是由 翟月雯 羊浩 周乐育 贺小毛 于 2021-09-08 设计创作，主要内容包括：本申请公开一种用于等温锻造的大型模具坯料的增材制备方法,包括步骤：基于预定形状,分别制备多个钛锆钼合金板状基元；基于预定形状,分别制备多个纯钽、铌钨合金和钽钨合金的箔状中间层；基于预定构造,形成装配体,使得装配体中箔状中间层夹在钛锆钼合金板状基元之间；借助于真空扩散焊炉,在高温真空的条件下对装配体施加轴向压力,以发生扩散连接,以获得初级坯；在高温、真空或惰性气体保护的条件下,对初级坯进行均匀化处理,以均匀初级坯中连接界面处的组织、成分；冷却经过均匀化处理的初级坯料,以获得模具坯料。该方法能够有效减弱大尺寸钛锆钼合金坯料中力学性能不均匀及性能较差的问题,尤其适于制备大型模具坯料。(The application discloses an additive manufacturing method of a large-scale die blank for isothermal forging, which comprises the following steps: respectively preparing a plurality of titanium-zirconium-molybdenum alloy plate-shaped elements based on a preset shape; respectively preparing a plurality of foil-shaped intermediate layers of pure tantalum, niobium-tungsten alloy and tantalum-tungsten alloy based on a preset shape; forming an assembly body based on a predetermined configuration such that a foil-like intermediate layer in the assembly body is sandwiched between the titanium-zirconium-molybdenum alloy plate-like elements; applying axial pressure to the assembly body under the condition of high-temperature vacuum by means of a vacuum diffusion welding furnace to generate diffusion connection so as to obtain a primary blank; homogenizing the primary blank under the conditions of high temperature, vacuum or inert gas protection to homogenize the structure and components of the connection interface in the primary blank; cooling the homogenized primary blank to obtain a die blank. The method can effectively solve the problems of uneven mechanical properties and poor performance of large-size titanium-zirconium-molybdenum alloy blanks, and is particularly suitable for preparing large-size die blanks.)

1. A preparation method of a large-scale die blank for isothermal forging is characterized by comprising the following steps:

respectively preparing a plurality of titanium-zirconium-molybdenum alloy plate-shaped elements with the thickness of 20-100 mm on the basis of a preset shape;

respectively preparing a plurality of foil-shaped intermediate layers of metal niobium-tungsten alloy or tantalum-tungsten alloy with the thickness of 40-150 micrometers on the basis of a preset shape;

sequentially assembling the titanium zirconium molybdenum alloy plate-like elements and the foil-like intermediate layer based on a predetermined configuration to form an assembly body such that the foil-like intermediate layer is sandwiched between the titanium zirconium molybdenum alloy plate-like elements in the assembly body;

by means of a vacuum diffusion welding furnace, at a joining temperature of 20-100 ℃ below the recrystallization temperature of the titanium zirconium molybdenum alloy, 10 DEG^-3-10^-2Applying axial pressure of 6-9MPa with the connection duration not less than 3 hours to the assembly body under the condition of Pa vacuum degree to enable the titanium-zirconium-molybdenum alloy plate-shaped element and the foil-shaped interlayer to be in diffusion connection so as to obtain a primary blank;

homogenizing the primary blank for 2-24 hours at a homogenizing temperature 50-150 ℃ lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy under the protection of vacuum or inert gas to homogenize the structure and components at the connecting interface in the primary blank;

cooling the homogenized primary blank to obtain a die blank.

2. The production method according to claim 1, wherein in the production of the plurality of titanium-zirconium-molybdenum alloy plate-like elements having a thickness of 10 to 30 mm, the titanium-zirconium-molybdenum alloy plate-like elements are machined, pre-ground, and polished so that the roughness Ra of the joint surfaces of the titanium-zirconium-molybdenum alloy plate-like elements and the foil-like intermediate layer is 0.4 to 0.8, and so that the parallelism between each of the joint surfaces and the pressure-receiving surface of the titanium-zirconium-molybdenum alloy plate-like elements subjected to the axial pressure is less than 0.02 mm.

3. The method according to claim 1, wherein the tantalum is pure tantalum having a purity of 99.5% or more, and the niobium-tungsten alloy or the tantalum-tungsten alloy is Nb- (2-10) W or Ta- (2-10) W (wt%).

4. The manufacturing method according to claim 1, wherein in manufacturing a plurality of foil-like intermediate layers of pure tantalum, niobium-tungsten alloy or tantalum-tungsten alloy having a thickness of 60 to 80 μm, the foil-like intermediate layers are soaked with 10wt% hydrochloric acid for 10 minutes and then ultrasonically cleaned with alcohol or acetone.

5. The method according to claim 1, wherein the joining temperature is 20-60 ℃ lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy, the axial pressure is 7-9MPa, and the joining time is 3-6 hours.

6. The method according to claim 1, wherein the homogenization temperature is 80-150 ℃ lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy, and the homogenization time is 5-12 hours.

7. The production method according to claim 1, wherein in cooling the primary slab subjected to the homogenization treatment, the primary slab is cooled from the homogenization temperature to 1000 ℃ at a cooling rate of 2 to 6 ℃/min, and is cooled from 1000 ℃ to 500 ℃ at a cooling rate of 10 to 15 ℃/min.

8. The production method according to claim 7, wherein in cooling the primary slab subjected to the homogenization treatment, after cooling to 500 ℃, the primary slab is held at a temperature of 500 ℃ for 1 hour to remove stress caused by the cooling.

Technical Field

The invention relates to a manufacturing method of a metal material, in particular to a preparation method of a large-scale die blank for isothermal forging, and particularly relates to a preparation method of a titanium-zirconium-molybdenum alloy die blank for isothermal forging.

Background

The isothermal forging is particularly suitable for the precise forming of materials which are difficult to deform, such as titanium alloy, nickel-based high-temperature alloy and the like, and have narrow forging temperature zone, poor plasticity and large deformation resistance. However, since the isothermal forging die is used at a high temperature and has higher rheological stress than a formed part, a higher demand is placed on the high temperature performance of the die material. At present, the working temperature of a die cavity of a die for isothermal forging of nickel-based high-temperature alloy and titanium alloy is more than 700-1200 ℃, and the die has high strength and hardness, good wear resistance and enough toughness in the temperature range. The titanium-zirconium-molybdenum alloy (TZM alloy for short) is an alloy which takes molybdenum (Mo) as a matrix and is added with a small amount of titanium (Ti), zirconium (Zr) and carbon (C), and has higher recrystallization temperature (1350-1400 ℃) than metal molybdenum, and more excellent high-temperature mechanical property and corrosion resistance. Therefore, the titanium-zirconium-molybdenum alloy is used as an important high-temperature-resistant structural material and is very suitable for manufacturing high-temperature-resistant dies for isothermal forging. However, because the melting point of the titanium-zirconium-molybdenum alloy is high (about 2640 ℃), the smelting or powder metallurgy preparation of the titanium-zirconium-molybdenum alloy with larger size has larger difficulty, and the phenomena of coarse crystals and component segregation are easy to occur. Moreover, because the titanium-zirconium-molybdenum alloy has larger high-temperature deformation resistance, the difficulty of refining grains and modifying large-size blanks by forging, rolling and other hot processing means is increased, the large-size blanks are easy to have the phenomenon of uneven structures and chemical components, and the mechanical properties of the blanks also have the trend of obviously reducing along with the increase of the sizes of the blanks.

When a large metal material is prepared, the existing method provides that a plurality of small primitives are stacked into a preset shape, then all the small primitives are packaged by electron beam welding to achieve the vacuum state among the primitives, the interlayer diffusion of all the small primitives is realized by large-scale deformation (upsetting) and high-temperature heat preservation to realize interlayer forge welding, and finally, the plurality of primitives are forge welded together to form a large metal blank. For example, chinese patent application CN 105598327 a, "layered multi-row stacking metal construction forming method", CN 107717341a "modular metal construction forming method", CN107876674A "metal grading construction forming method", and CN 105522349 a "homogeneous metal construction forming method" are all methods of forge welding a plurality of small-sized elements into a large-sized metal part by using construction forming process. However, titanium-zirconium-molybdenum alloys, which are high-melting-point alloys that are difficult to deform, have high deformation resistance at high temperatures, and are difficult to achieve forging deformation with large deformation, i.e., difficult to achieve upsetting. Therefore, for the titanium-zirconium-molybdenum alloy, the difficulty of realizing interlayer interface diffusion of each small unit is higher by applying pressure at high temperature, and the difficulty of realizing good forge welding bonding between each layer of units is higher. Meanwhile, the titanium-zirconium-molybdenum alloy has poor welding performance, and a welding seam with good performance is difficult to obtain through electron beam welding, and the structure and the performance of the titanium-zirconium-molybdenum alloy can be obviously changed due to high temperature generated in the electron beam welding and packaging process. Electron beam welding also adds process complexity and manufacturing costs. Moreover, the titanium-zirconium-molybdenum alloy has the high-temperature characteristic of easy oxidation and volatilization under the high-temperature condition, and the conventional forge welding construction process in the atmosphere is not suitable for the titanium-zirconium-molybdenum alloy. Therefore, the above-mentioned forge welding-based construction forming process is not suitable for titanium-zirconium-molybdenum alloy, and a method suitable for preparing large-scale titanium-zirconium-molybdenum alloy materials needs to be developed.

Disclosure of Invention

In view of the above problems in the prior art, the present application provides an additive manufacturing method for isothermally forging a large-sized die blank, which can effectively reduce the influence of non-uniformity in structure, composition and performance in a titanium-zirconium-molybdenum alloy blank on the service performance of a large-sized alloy, and is particularly suitable for manufacturing a large-sized titanium-zirconium-molybdenum die blank.

In order to achieve the above object, the present application provides a method for preparing a large die blank for isothermal forging, comprising the steps of:

-preparing a plurality of titanium zirconium molybdenum alloy plate-like elements having a thickness of 20-100 mm, respectively, based on a predetermined shape;

-preparing a plurality of foil-like intermediate layers of tantalum, niobium-tungsten alloy or tantalum-tungsten alloy, respectively, having a thickness of 40-150 μm, based on a predetermined shape;

-successively assembling the titanium zirconium molybdenum alloy plate elements and the foil-like intermediate layer on the basis of a predetermined configuration to form an assembly body such that the foil-like intermediate layer is sandwiched between the titanium zirconium molybdenum alloy plate elements in the assembly body;

10 at a joining temperature of 20-100 ℃ below the recrystallization temperature of the titanium zirconium molybdenum alloy by means of a vacuum diffusion welding furnace^-3-10^-2Applying axial pressure of 6-9MPa which is not less than 3 hours of connection duration to the assembly body under the condition of Pa vacuum degree to enable the titanium-zirconium-molybdenum alloy plate-shaped element and the foil-shaped interlayer to be in diffusion connection so as to obtain a primary blank;

-homogenizing the primary blank for a homogenization period of 2-24 hours at a homogenization temperature 50-150 ℃ lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy, under vacuum or under inert gas protection, in order to homogenize the structure and composition at the joint interface in the primary blank;

-cooling the homogenized primary blank to obtain a die blank.

By using the diffusion bonding technology and adopting the foil-shaped material of tantalum, niobium-tungsten alloy or tantalum-tungsten alloy as the intermediate layer, the homogenization process is added, the construction forming process is improved, and the preparation of large-scale die blanks by using the titanium-zirconium-molybdenum alloy is realized. Without being bound by theory, it is believed that the additive manufacturing method according to the present application promotes interdiffusion between the molybdenum element of the titanium-zirconium-molybdenum alloy plate-shaped element and the metal element of the foil-shaped intermediate layer, forms a diffusion layer at the connection interface of the element and the intermediate layer, and effectively realizes interconnection of a plurality of elements through the foil-shaped intermediate layer, thereby enabling the preparation of a large mold blank of the titanium-zirconium-molybdenum alloy by using a building and forming process. In addition, because the temperature of the diffusion bonding and homogenization treatment is lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy, the additive preparation method does not cause obvious changes to the structure and the performance of the titanium-zirconium-molybdenum alloy plate-shaped element.

In one possible implementation manner of the present application, in the preparing of the plurality of titanium-zirconium-molybdenum alloy plate-shaped elements with the thickness of 30-100 mm, the titanium-zirconium-molybdenum alloy plate-shaped elements are machined, pre-ground and polished, so that the roughness Ra of the connection surface between the titanium-zirconium-molybdenum alloy plate-shaped elements and the foil-shaped intermediate layer is 0.4-0.8, and the parallelism between each connection surface and the pressed surface of the titanium-zirconium-molybdenum alloy plate-shaped elements, which is subjected to the axial pressure, is less than 0.02 mm.

In one possible implementation manner of the application, the tantalum is pure tantalum with the purity of more than or equal to 99.5%, and the niobium-tungsten alloy or the tantalum-tungsten alloy is Nb- (2-10) W or Ta- (2-10) W (wt%).

From the above, the foil-shaped intermediate layer is further limited, so that good interdiffusion between the foil-shaped intermediate layer and the titanium-zirconium-molybdenum alloy plate-shaped element is facilitated, and the performance of the die at high temperature is further improved.

In one possible implementation of the present application, in preparing a plurality of foil-like intermediate layers of tantalum, niobium-tungsten alloy, or tantalum-tungsten alloy having a thickness of 60 to 80 μm, the foil-like intermediate layers are soaked with 10wt% hydrochloric acid for 10 minutes, and then the foil-like intermediate layers are ultrasonically cleaned with alcohol or acetone.

By the above, through further limitation on the preparation of the titanium-zirconium-molybdenum alloy plate-shaped element and the foil-shaped intermediate layer, specific parallelism is provided between the surfaces to be connected and between the connecting surface and the pressed surface, and the surfaces to be connected have specific roughness and cleanliness, so that the connection quality between the element and the intermediate layer is favorably improved, and the performance of the die at high temperature is better.

In one possible implementation manner of the present application, the connection temperature is 20-60 ℃ lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy, the axial pressure is 7-9MPa, and the connection time is 3-6 hours.

In one possible implementation manner of the present application, the homogenization temperature is a temperature 80-150 ℃ lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy, and the homogenization time is 5-12 hours.

In one possible realization of the present application, in cooling the homogenized primary blank, cooling is carried out from the homogenization temperature to 1000 ℃ at a cooling rate of 2-6 ℃/min and from 1000 ℃ to 500 ℃ at a cooling rate of 10-15 ℃/min.

In one possible implementation of the present application, in cooling the homogenized primary blank, after cooling to 500 ℃, it is kept at a temperature of 500 ℃ for 1 hour to remove the stress caused by the cooling.

By the above, by further limiting the process parameters such as the connection temperature, the axial connection pressure, the connection time, the homogenization temperature, the homogenization time, the cooling rate and the like, the mutual diffusion of the molybdenum element between the titanium-zirconium-molybdenum alloy element and the foil-shaped intermediate layer and the intermediate layer metal element is further promoted, the molybdenum content of the intermediate layer is further promoted, and the performance of the die at high temperature is further improved.

In one possible implementation of the present application, the homogenization and cooling processes are performed in a vacuum diffusion furnace. In other words, homogenization and subsequent controlled cooling can be performed directly after the press-connection by adjusting the temperature of the vacuum diffusion furnace.

In one possible implementation of the present application, the homogenization and cooling processes are performed in a vacuum furnace or an atmosphere protection furnace. In other words, after waiting for the vacuum diffusion furnace to cool down to remove the joint, the subsequent homogenization and controlled cooling process is completed in the vacuum furnace or the atmosphere protection furnace. The method can shorten the service time of the vacuum diffusion welding furnace and improve the production efficiency.

The foregoing of the present application will be more readily understood in the following description of various embodiments with reference to the accompanying drawings.

Drawings

The drawings of the present application are provided below for the purpose of illustrating the present application in a more intuitive form, and are exemplary and not intended to limit the scope of the present application.

FIG. 1 is a schematic view of the construction of an assembly according to one embodiment of the present application;

FIG. 2 is a schematic illustration of a diffusion bond according to an embodiment of the present application;

FIG. 3 is a schematic illustration of a homogenization process according to one embodiment of the present application;

FIG. 4 is a schematic illustration of a configuration of a die blank according to one embodiment of the present application.

Detailed Description

In order that the application may be more readily understood, the application is further described below in connection with specific embodiments. The experimental methods described in the application are conventional methods unless otherwise specified; the materials mentioned are commercially available unless otherwise specified. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. In the case of inconsistency, the meaning described in the present specification or the meaning derived from the content described in the present specification shall control. In addition, the terminology used herein is for the purpose of describing embodiments of the present application only and is not intended to be limiting of the present application.

To accurately describe the technical contents in the present application and to accurately understand the present invention, the words and terms used in the present specification are explained or defined as follows before describing the embodiments.

The words "one embodiment" or "an embodiment" as used in this specification means that a particular feature, step, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, steps or characteristics may be combined in any suitable manner in one or more embodiments, as would be apparent to one of ordinary skill in the art from this disclosure.

The term "vacuum diffusion welding furnace" as used in the specification and claims is an apparatus capable of applying pressure to a workpiece while providing a vacuum environment for the workpiece.

The term "vacuum furnace" as used in the specification and claims is a device capable of providing a vacuum environment for a workpiece.

The term "atmosphere protection furnace" as used in the specification and claims is an apparatus capable of providing an inert gas environment to a workpiece.

The term "titanium zirconium molybdenum alloy", also known as TZM alloy, as used in the specification and claims, has a composition of 0.4wt% to 0.55 wt% titanium, 0.06 wt% to 0.12 wt% zirconium, and 0.01wt% to 0.04wt% carbon. On one hand, titanium and zirconium elements are dissolved into a molybdenum substrate to cause lattice distortion, so that the solid solution strengthening of the titanium-zirconium-molybdenum alloy is realized; on the other hand, titanium reacts with carbon element of zirconium element to form fine and dispersed TiC and ZrC particles, so that second phase strengthening is realized. Due to the alloying action, the TZM alloy has the characteristics of high melting point, small expansion coefficient, low steam pressure and good electric and heat conducting properties of the metal molybdenum, and has higher recrystallization temperature (1350-1400 ℃) and more excellent high-temperature mechanical property and corrosion resistance.

The term "diffusion bonding" as used in the specification and claims is a process in which bonded surfaces are brought into intimate contact by plastic deformation under the action of high temperature and pressure, and inter-atomic diffusion occurs over time to form a reliable joint. The method is particularly suitable for preparing the joint with larger connecting area and higher requirements on dimensional accuracy and mechanical property.

The term "isothermal forging" as used in the specification and claims is a forging technique in which the die and the formed part are at substantially the same temperature.

The term "construction shape" as used in the specification is an additive manufacturing method for manufacturing a large metal blank using a plurality of metal blanks having a relatively small volume as construction elements.

The expression "axial" as referred to in the description and claims is the direction perpendicular to the contact surface of the titanium zirconium molybdenum alloy plate element with the foil intermediate layer.

The technical solution of the present application will be described in detail with reference to fig. 1 to 4.

Fig. 1 shows an assembly 3 according to one embodiment of the present application, which is square in cross-section. As shown in fig. 1, the assembly body 3 is composed of four titanium zirconium molybdenum alloy plate-like elements 1 and three foil-like intermediate layers 2, the foil-like intermediate layers 2 being sandwiched between the titanium zirconium molybdenum alloy plate-like elements 1, respectively. In this embodiment, each of the titanium-zirconium-molybdenum alloy plate-like elements 1 is prepared to have a uniform shape, and each of the foil-like intermediate layers 2 is prepared to have a uniform shape, to form an assembly body 3 having such a cross section. It is to be understood that in other embodiments of the present application, it is possible to prepare each of the titanium zirconium molybdenum alloy plate-like elements 1 to be non-uniform in shape and/or to prepare each of the foil-like intermediate layers 2 to be non-uniform in shape so as to form a cross section of a desired shape, thereby forming an assembly body 3 of a desired configuration. For example, each of the titanium-zirconium-molybdenum alloy plate element 1 and the foil-like intermediate layer 2 may be prepared in different shapes so that the fitting 3 has a smoothly curved profile in the thickness direction from the top down. For example, some of the titanium-zirconium-molybdenum alloy plate-like elements 1 and the foil-like intermediate layer 2 may be prepared in a hollow shape so that the assembly body 3 has a hollow cavity, thereby enabling a mold blank as a mold to prepare a molded article using the hollow cavity.

FIG. 2 shows a schematic diagram of a diffusion bond according to one embodiment of the present application. After the assembly body 3 is placed into the vacuum diffusion furnace 11, the vacuum diffusion furnace 11 is started, so that the temperature in the vacuum diffusion furnace 11 reaches a connection temperature which is 20-100 ℃ lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy, and the vacuum degree reaches 10^-3-10^-2Pa. Then, the vacuum diffusion furnace 11 is caused to apply a pressure of 6 to 9MPa to the assembly 3 in the axial direction shown by the arrow, and is maintained at that pressure for not less than 3 hours. The obtained primary blank 4 is then taken out of the vacuum diffusion furnace 11.

It will be appreciated that, at the time of formation of the primary blank 4, diffusion bonding has taken place between the titanium zirconium molybdenum alloy plate element 1 and the foil-like intermediate layer 2, the molybdenum element in the titanium zirconium molybdenum alloy plate element 1 having diffused into the foil-like intermediate layer 2, and the metal element in the foil-like intermediate layer 2 having diffused into the titanium zirconium molybdenum alloy plate element 1, so that a new intermediate structure 5 (see fig. 3) is formed between the titanium zirconium molybdenum plate elements 1'. The intermediate structure 5 has, at the junction interface, diffusion layers 7 and possibly metal foil layers present between the diffusion layers 7 (in other embodiments, the foil-like intermediate layer 2 is considered to be partially or completely absent, due to the complete penetration of the molybdenum element into the foil-like intermediate layer to form a solid solution). Due to the formation of the new intermediate structure 5, the titanium zirconium molybdenum plate element 1' can be considered to be thinner than the titanium zirconium molybdenum alloy plate element 1 at microscopic angles, while the metal foil layer is thinner than the foil-like intermediate layer 2.

FIG. 3 shows a schematic diagram of a homogenization process according to one embodiment of the present application. After the primary billet 4 is placed in the vacuum furnace 12 or the atmosphere protection furnace 13, the vacuum furnace 12 or the atmosphere protection furnace 13 is started to make the degree of vacuum 10^-3-10^-2Pa or filling inert gas in the furnace, and enabling the furnace temperature to reach a homogenization temperature which is 50-150 ℃ lower than the recrystallization temperature of the titanium-zirconium-molybdenum alloy. After reaching the homogenization temperature, the temperature is maintained for 2 to 24 hours to homogenize the structure and composition at the joining interface in the primary blank 4 to form the die blank 6 (see fig. 4).

Fig. 4 shows a die blank 6 according to an embodiment of the present application. The die blank 6 is composed of a titanium-zirconium-molybdenum plate-like element 1' and a diffusion layer 7. In the present embodiment, further interdiffusion of the primary blank 4 occurs during homogenization, and the metal foil layer originally remaining in the intermediate structure 5 disappears completely with further interdiffusion, whereupon the intermediate structure 5 transforms into a diffusion layer 7 consisting of a molybdenum-titanium/niobium solid solution, thereby forming the die blank 6.

In some embodiments of the present application, particularly embodiments in which a thicker tantalum foil, niobium tungsten alloy foil, or tantalum tungsten foil is used as the intermediate layer, a thickness of the metal foil layer remains in the die blank 6. However, since tantalum foil, niobium-tungsten and tantalum-tungsten are high melting point alloys and have high temperature strength, the remaining metal foil layer does not significantly affect the high temperature properties of the die blank 6, while the already formed diffusion layer is sufficient to provide the mechanical properties required for the die blank 6 as a die. Furthermore, in the embodiment mode in which a thicker tantalum foil, niobium-tungsten foil, or tantalum-tungsten foil is used as the intermediate layer in particular, the element distribution of the diffusion layer 7 is not uniform, and the molybdenum element is distributed in a gradient concentration. However, since the molybdenum element can improve the high temperature performance of the intermediate layer, the diffusion layer 7 in which the titanium element is distributed in a gradient concentration does not significantly affect the high temperature performance of the die blank 6, while the diffusion layer that has been formed is sufficient to provide the mechanical properties required for the die blank 6 as a die.

In summary, the present application has the following advantages.

By adding the tantalum foil, the niobium-tungsten foil or the tantalum-tungsten foil as the intermediate layer, the problems that the titanium-zirconium-molybdenum alloy is high in high-temperature yield strength, high in melting point, large in difficulty in plastic deformation of a connection interface and difficult to diffuse are solved.

The method solves the problems that a titanium-zirconium-molybdenum alloy large blank is difficult to prepare, and has uneven performance and poor performance by adding a specific intermediate layer, a homogenization process and a cooling process on the basis of a metal construction process. In addition, the blank after diffusion connection is subjected to homogenization treatment, so that the middle layer element and the molybdenum element of the titanium-zirconium-molybdenum alloy are fully diffused mutually, an obvious diffusion layer is formed at the element connection interface, and the bonding strength is high. In addition, the middle layer has higher normal temperature and high temperature resistance strength and is fully interdiffused with the titanium-zirconium-molybdenum alloy element, and each titanium-zirconium-molybdenum element connecting interface has higher normal temperature and high temperature performance.

The connection temperature of the titanium zirconium molybdenum alloy is lower than the recrystallization temperature of the titanium zirconium molybdenum alloy by 20-100 ℃. After the titanium-zirconium-molybdenum alloy plate-shaped elements are subjected to diffusion connection, the structure and the performance are not obviously changed.

The method and the device do not need to carry out vacuum electron beam welding and packaging on each element, and have relatively simple process and lower manufacturing cost.

The method and the device reduce the requirements of diffusion bonding on the surface roughness, the bonding temperature, the bonding pressure and the heat preservation time of the titanium-zirconium-molybdenum alloy bonding surface. The application also avoids the problems of limited capacity and high investment of powder metallurgy equipment.

The shapes of the elements can be designed according to actual conditions, the diffusion additive manufacturing of solid, hollow and irregular blanks can be realized, and the process is flexible and strong in adaptability.

Compared with the existing metal construction method, the method is more suitable for construction and manufacturing of high-melting-point refractory alloys and difficult-deformation alloys, such as molybdenum alloys, tungsten alloys and nickel-based alloys.

For ease of implementation, exemplary embodiments of the present application are described below.

< example 1>

This example is an isothermal forged titanium zirconium molybdenum die blank for a nickel base superalloy blade with dimensions of 200 x 60 mm (length x width x thickness). The isothermal forging titanium zirconium molybdenum die blank adopts 3 pieces of 200X 20 mm (length X width X thickness) titanium zirconium molybdenum alloy plate-shaped elements and 2 pieces of Nb-10W foil intermediate layers with the length and width of 200X 200 mm and the thickness of 80 microns, and is subjected to diffusion bonding additive manufacturing in a vacuum diffusion furnace and diffusion homogenization treatment in the vacuum furnace. The method comprises the following specific steps:

step 1: machining, pre-grinding and polishing the titanium-zirconium-molybdenum alloy plate-shaped element to ensure that the roughness Ra of the titanium-zirconium-molybdenum alloy connecting surface is 0.4-0.8 and the parallelism of the titanium-zirconium-molybdenum alloy connecting surface and a pressure surface contacted with a pressure head of a vacuum diffusion furnace is less than 0.02 mm.

Step 2: soaking the foil-shaped middle layer in 10wt% hydrochloric acid for 10 min, washing with clear water, ultrasonic cleaning in alcohol or acetone, and air drying.

And step 3: and (3) assembling the titanium-zirconium-molybdenum alloy plate-shaped elements treated in the steps (1) and (2) and the Nb-10W foil intermediate layer in a staggered manner, and stacking into 5 layers (3 layers of titanium-zirconium-molybdenum alloy plates and 2 layers of foil intermediate layers) to form an assembly body. The niobium foil intermediate layer can be fixed on the titanium-zirconium-molybdenum alloy plate-shaped element in an energy storage welding mode to prevent dislocation during assembly.

And 4, step 4: and (3) placing the assembly body into a vacuum diffusion furnace, and applying axial pressure of 0.2MPa to the assembly body for fixing. Then, vacuum pumping is started, and when the vacuum degree reaches 2 multiplied by 10^-3And Pa, starting heating and raising the temperature. In the first stage, the temperature is increased to 500 ℃ at the speed of 15 ℃/minute and is kept for 30 minutes, so that oil stains in the furnace and on the surface of a workpiece are volatilized; in the second stage, the temperature is increased to 1000 ℃ at the speed of 10 ℃/min and is kept for 15 min, so that the temperature in the furnace is uniform; the third stage was ramped up at a rate of 5 minutes/minute to a diffusion bonding temperature of 1330 ℃. After reaching a joining temperature of 1330 ℃, an axial pressure of 9MPa is applied to the assembly body, and heat preservation is carried out for 6 hours to carry out diffusion joining, thereby obtaining a primary blank.

And 5: after the diffusion bonding heat preservation is finished, the temperature in the furnace is reduced to 1220 ℃, the axial pressure is removed, the heat preservation is carried out for 8 hours, and the homogenization treatment is carried out to eliminate the bonding stress and homogenize the components and the tissues at the bonding interface.

Step 6: and after the homogenization and heat preservation are finished, cooling is started. In the stage of cooling to 1000 ℃ at the temperature of 1200 ℃, the cooling rate is 2-6 ℃/min; in the stage of 1000-500 deg.C, the cooling rate is 10-15 deg.C/min. When the temperature reaches 500 ℃, the temperature is kept for 1 hour to carry out annealing stress relief treatment. Cooling to room temperature along with the furnace after stress removal, and obtaining the titanium-zirconium-molybdenum alloy die blank.

< example 2>

This example is a nickel-base superalloy blisk isothermal forged titanium zirconium molybdenum die blank with dimensions 500 x 200 mm (length x width x thickness). The isothermal forging titanium zirconium molybdenum die blank adopts 4 pieces of 500 x 50 mm (length x width x thickness) titanium zirconium molybdenum alloy plate-shaped elements and 3 pieces of 500 x 500 mm Ta-2.5W foil intermediate layers with the thickness of 60 microns, and is subjected to diffusion bonding additive manufacturing in a vacuum diffusion furnace and diffusion homogenization treatment in the vacuum furnace. The method comprises the following specific steps:

step 1: machining, pre-grinding and polishing the titanium-zirconium-molybdenum alloy plate-shaped element to ensure that the roughness Ra of the titanium-zirconium-molybdenum alloy connecting surface is 0.4-0.8 and the parallelism of the titanium-zirconium-molybdenum alloy connecting surface and a pressure surface contacted with a pressure head of a vacuum diffusion furnace is less than 0.02 mm.

Step 2: soaking the foil-shaped middle layer in 10wt% hydrochloric acid for 10 min, washing with clear water, ultrasonic cleaning in alcohol or acetone, and air drying.

And step 3: and (3) assembling the titanium-zirconium-molybdenum alloy plate-shaped elements treated in the steps (1) and (2) and the Ta-2.5W foil intermediate layer in a staggered manner, and stacking into 7 layers (4 layers of titanium-zirconium-molybdenum alloy plates and 3 layers of foil intermediate layers) to form an assembly body. The niobium foil intermediate layer can be fixed on the titanium-zirconium-molybdenum alloy plate-shaped element in an energy storage welding mode to prevent dislocation during assembly.

And 4, step 4: and (3) placing the assembly body into a vacuum diffusion furnace, and applying axial pressure of 0.2MPa to the assembly body for fixing. Then, vacuum pumping is started, and when the vacuum degree reaches 2 multiplied by 10^-3And beginning heating and increasing the temperature at Pa. In the first stage, the temperature is increased to 500 ℃ at the speed of 15 ℃/minute and is kept for 30 minutes, so that oil stains in the furnace and on the surface of a workpiece are volatilized; in the second stage, the temperature is increased to 1000 ℃ at the speed of 10 ℃/min and is kept for 15 min, so that the temperature in the furnace is uniform; the third stage was ramped up at a rate of 5 minutes/minute to a diffusion bonding temperature of 1300 ℃. After reaching the connection temperature of 1330 ℃, applying axial pressure of 7MPa to the assembly body, preserving heat for 5 hours, and performing diffusion connection. And after the diffusion connection heat preservation is finished, carrying out air cooling along with the furnace to room temperature and taking out the primary blank.

And 5: and (3) putting the primary blank into an atmosphere furnace, flushing nitrogen for protection, and heating to raise the temperature. The furnace temperature was raised to 1250 ℃ and held for 12 hours for homogenization.

Step 6: and after the homogenization and heat preservation are finished, cooling is started. In the stage of cooling to 1000 ℃ at 1250 ℃, the cooling rate is 2-6 ℃/min; in the stage of 1000-500 deg.C, the cooling rate is 10-15 deg.C/min. When the temperature reaches 500 ℃, the temperature is kept for 1 hour to carry out annealing stress relief treatment. And cooling to room temperature along with the furnace after stress removal, thus obtaining the titanium-zirconium-molybdenum die blank.

< example 3>

This example is an isothermal forged titanium zirconium molybdenum die blank for a titanium alloy compressor disk having dimensions 400 x 160 mm (length x width x thickness). The isothermal forging titanium zirconium molybdenum die blank adopts 4 pieces of 400 x 40 mm (length x width x thickness) titanium zirconium molybdenum alloy plate-shaped elements, 3 pieces of Ta-10W foils with the length and width of 400 x 400 mm and the thickness of 60 microns as intermediate layers, and is subjected to diffusion bonding additive manufacturing in a vacuum diffusion furnace and diffusion homogenization treatment in the vacuum furnace. The method comprises the following specific steps:

step 1: machining, pre-grinding and polishing the titanium-zirconium-molybdenum alloy plate-shaped element to ensure that the roughness of the titanium-zirconium-molybdenum alloy connecting surface is Ra0.4-0.8 and the parallelism of the titanium-zirconium-molybdenum alloy connecting surface and a pressure surface contacted with a pressure head of a vacuum diffusion furnace is less than 0.02 mm.

Step 2: soaking the foil-shaped middle layer in 10wt% hydrochloric acid for 10 min, washing with clear water, ultrasonic cleaning in alcohol or acetone, and air drying.

And step 3: and (3) assembling the titanium-zirconium-molybdenum alloy plate-shaped element treated in the steps (1) and (2) and the Ta-10W foil intermediate layer in a staggered manner, and stacking into 7 layers (4 layers of titanium-zirconium-molybdenum alloy plates and 3 layers of foil intermediate layers) to form an assembly body. The titanium foil intermediate layer can be fixed on the titanium-zirconium-molybdenum alloy plate-shaped element in an energy storage welding mode so as to prevent dislocation during assembly.

And 4, step 4: and (3) placing the assembly body into a vacuum diffusion furnace, and applying axial pressure of 0.2MPa to the assembly body for fixing. Then, vacuum pumping is started, and when the vacuum degree reaches 2 multiplied by 10^-3And beginning heating and increasing the temperature at Pa. In the first stage, the temperature is increased to 500 ℃ at the speed of 15 ℃/minute and is kept for 30 minutes, so that oil stains in the furnace and on the surface of a workpiece are volatilized; in the second stage, the temperature is increased to 1000 ℃ at the speed of 10 ℃/min and is kept for 15 min, so that the temperature in the furnace is uniform; the third stage was ramped up at a rate of 5 minutes/minute to a diffusion bonding temperature of 1300 ℃. After the connection temperature of 1300 ℃, applying 6MPa axial pressure to the assembly body, preserving heat for 3 hours, and performing diffusion connection to obtain a primary blank.

And 5: after the diffusion connection heat preservation is finished, the temperature in the furnace is reduced to 1220 ℃, the axial pressure is removed, the heat preservation is carried out for 10 hours, the homogenization treatment is carried out, the connection stress is eliminated, and the component and tissue homogenization treatment at the connection interface is carried out.

Step 6: and after the homogenization heat preservation is finished, cooling is started. In the stage of cooling to 1000 ℃ at the temperature of 1220 ℃, the cooling rate is 2-6 ℃/min; in the stage of 1000-500 deg.C, the cooling rate is 10-15 deg.C/min. When the temperature reaches 500 ℃, the temperature is kept for 1 hour to carry out annealing stress relief treatment. And cooling to room temperature along with the furnace after stress removal, thus obtaining the titanium-zirconium-molybdenum die blank.

< example 4>

This example is an isothermal forged titanium zirconium molybdenum die blank for a titanium alloy impeller disk having dimensions phi 300 x 150 mm (length x width x thickness). The isothermal forging titanium zirconium molybdenum die blank adopts 3 pieces of titanium zirconium molybdenum alloy plate-shaped elements with the diameter of 300mm and the thickness of 50 mm, 2 pieces of tantalum foil with the diameter of 300mm and the thickness of 40 microns as an intermediate layer, and is subjected to diffusion bonding additive manufacturing in a vacuum diffusion furnace and diffusion homogenization treatment in the vacuum furnace. The method comprises the following specific steps:

step 1: machining, pre-grinding and polishing the titanium-zirconium-molybdenum alloy plate-shaped element to ensure that the roughness of the titanium-zirconium-molybdenum alloy connecting surface is Ra0.4-0.8 and the parallelism of the titanium-zirconium-molybdenum alloy connecting surface and a pressure surface contacted with a pressure head of a vacuum diffusion furnace is less than 0.02 mm.

Step 2: soaking the foil-shaped middle layer in 10wt% hydrochloric acid for 10 min, washing with clear water, ultrasonic cleaning in alcohol or acetone, and air drying.

And step 3: and (3) assembling the titanium-zirconium-molybdenum alloy plate-shaped elements treated in the steps (1) and (2) in a staggered manner with the tantalum foil intermediate layer, and stacking into 5 layers (3 layers of titanium-zirconium-molybdenum alloy plates and 2 layers of foil intermediate layer) to form an assembly body. The titanium foil intermediate layer can be fixed on the titanium-zirconium-molybdenum alloy plate-shaped element in an energy storage welding mode so as to prevent dislocation during assembly.

And 4, step 4: and (3) placing the assembly body into a vacuum diffusion furnace, and applying axial pressure of 0.2MPa to the assembly body for fixing. Then, vacuum pumping is started, and when the vacuum degree reaches 2 multiplied by 10^-3And beginning heating and increasing the temperature at Pa. In the first stage, the temperature is increased to 500 ℃ at the speed of 15 ℃/minute and is kept for 30 minutes, so that oil stains in the furnace and on the surface of a workpiece are volatilized; in the second stage, the temperature is increased to 1000 ℃ at the speed of 10 ℃/min and is kept for 15 min, so that the temperature in the furnace is uniform; the third stage was ramped up at a rate of 5 minutes/minute to a diffusion bonding temperature of 1320 ℃. After reaching the connection temperature of 1320 ℃, applying 6MPa axial pressure to the assembly body, preserving heat for 3 hours, and performing diffusion connection to obtain a primary blank.

And 5: after the diffusion bonding heat preservation is finished, the temperature in the furnace is reduced to 1200 ℃, the axial pressure is removed, the heat preservation is carried out for 12 hours, the homogenization treatment is carried out, the bonding stress is eliminated, and the composition and the structure homogenization treatment at the bonding interface is carried out.

Step 6: and after the homogenization heat preservation is finished, cooling is started. In the stage of cooling to 1000 ℃ at the temperature of 1200 ℃, the cooling rate is 2-6 ℃/min; in the stage of 1000-500 deg.C, the cooling rate is 10-15 deg.C/min. When the temperature reaches 500 ℃, the temperature is kept for 1 hour to carry out annealing stress relief treatment. And cooling to room temperature along with the furnace after stress removal, thus obtaining the titanium-zirconium-molybdenum die blank.

The foregoing is considered as illustrative of the preferred embodiments of the invention and the technical principles employed. It will be understood by those skilled in the art that the present application is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the application. Therefore, although the present application has been described in more detail with reference to the above embodiments, the present application is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present application.