CN111761883A - A kind of titanium-aluminum powder composite rod and its preparation device - Google Patents

Abstract

The invention is a titanium-aluminum powder composite bar and a preparation device thereof. The technical scheme of the invention utilizes the good fluidity of the powder material. Under the action of a step-change deformation, the pores between the powder particles completely disappear, and full density is achieved. At the same time, the outer layer metal and the inner layer metal form a whole through excessive organization, so as to realize the integration of solidification-organization-forming of powder components. Compared with the powder rolling method and the spray deposition method, the process flow is greatly shortened and the cost is reduced, thereby preparing a dense and fine recrystallized structure.

Description

A kind of titanium-aluminum powder composite rod and its preparation device

technical field

The invention relates to a titanium-aluminum powder composite bar and a preparation device thereof, belonging to the technical field of thermal processing.

Background technique

In the temperature range of 700~850℃, the specific strength of TiAl alloy is significantly higher than that of ordinary titanium alloy and nickel-based superalloy. TiAl alloy is used, and the structural mass of each stage of low-pressure turbine is reduced by 45.5kg. The as-cast microstructure and plasticity of TiAl alloys are relatively low. Hot processing such as forging, extrusion and rolling can effectively refine the microstructure and reduce the degree of component segregation, thereby improving the overall mechanical properties of the alloy. Titanium-aluminum bimetallic composite bar uses aluminum alloy as the inner metal of the tube as the stress layer, and the outer side of the tube is covered with a layer of titanium alloy as the protective layer. This material has the characteristics of low density, high strength and excellent welding performance of aluminum alloy. , and has the characteristics of high temperature resistance, corrosion resistance and impact resistance. In addition, the composite of the bimetal can save costs to a large extent and make the pipe lightweight, so it has been highly valued by some countries in recent years and has been used in aviation, military armor and other fields.

There are many processing methods for metal layered composite materials. There are generally two methods for powder metallurgy materials: powder rolling method and spray deposition method. Among them, there are two powder rolling methods: one is to loose powder on the base metal strip, and then through powder rolling and sintering to form bimetallic composite materials; the other is to use two funnels to supply powder at the same time, rolling A bimetal powder strip is made, and further sintered and rolled to obtain a bimetal composite material. This method is characterized by a long cycle and is generally used for the preparation of plate-shaped components. The spray deposition method is to make molten liquid metal flow out from the guide tube at the bottom of the crucible under the action of air pressure or self-weight to form a stable metal liquid flow. When the metal liquid flow passes through the atomizer, it is dispersed into extremely fine metal by high-pressure inert gas. Liquid particle jet, some of the small particles in the jet are frozen and solidified, and some large particles can remain in the liquid phase, in a solid or semi-solid state. The deposited layer, which adheres to the substrate, forms a composite material. The limitation of this method is that the deposit forms an excessively thick liquid phase layer on the top, which will degenerate into a general cast structure of soil, so it is difficult to prepare thick-walled components. In addition, due to the uneven distribution of substances in the metal jet, the dimensional accuracy of the deposited layer is difficult. Low.

SUMMARY OF THE INVENTION

The present invention is designed to provide a titanium-aluminum powder composite bar and a preparation device thereof just for the above-mentioned deficiencies in the existing domestic prior art, the purpose of which is to improve the production efficiency of the titanium-aluminum bimetal composite bar, and to improve the its microstructure.

The purpose of this invention is to realize through the following technical solutions:

The titanium-aluminum powder composite bar has a layered structure from the core to the outside, the core is a cylinder of metal titanium, the outer layer is an annular metal aluminum layer, and then an annular metal titanium layer, and so on, forming Titanium-aluminum composite bar.

In one implementation, the core and the outward layered structures are all made of metal aluminum powder and metal titanium powder.

In one implementation, the core and outward laminar structures are a total of four layers.

In one implementation, the diameter of the core is the same as the thickness of its outward layers.

The technical solution of the present invention provides a device for preparing the above-mentioned titanium-aluminum powder composite rod, the device includes a curing cavity and a forming cavity, and the two parts are connected together and placed coaxially and horizontally, wherein:

The curing cavity includes an annular upper cavity 12 and an upper indenter 15. The upper indenter 15 is sleeved in the upper cavity 12 and is a transition fit, and an annular primary extrusion die 11 is connected to the rear end of the upper cavity 12. ;

The rear end of the primary extrusion die 11 is the forming cavity, which is the middle die cavity 10, the secondary extrusion die 5 and the lower die cavity 7 in sequence. transitional cooperation;

The curing cavity and the forming cavity are installed on the base 13 through the bracket 3, and the left hydraulic station 14 and the right hydraulic station 9 are respectively provided in the front and rear of the base 13 to supply the curing cavity and the forming cavity through the hydraulic pipe 1. components provide hydraulic actuation;

The components of the curing cavity and the forming cavity. The upper cavity 12, the primary extrusion die 11, the middle die cavity 10, the secondary extrusion die 5, and the lower die cavity 7 are provided between the insulation cotton 4 and the locking ring 16. Connection is fixed.

In one implementation, the secondary extrusion die 5 and the bracket 3 at the bottom of the lower die cavity 7 are mounted on the slide rail 8 on the base 13 and can independently move horizontally along the axial direction.

In an implementation, the inner hole of the secondary extrusion die 5 is tapered, and the difference between the maximum inner diameter and the minimum inner diameter is 1/20 of the length of the secondary extrusion die 5 .

In one implementation, the curing cavity and the forming cavity are made of steel material with a breaking strength exceeding 2000 MPa.

The features and beneficial effects that the technical solution of the present invention has are:

The titanium-aluminum powder composite bar proposed by the invention is obtained based on the research on the plastic forming technology of the powder metallurgy bimetal composite bar, and is mainly aimed at the long period of the current domestic metal layered composite material processing method and the poor microstructure distribution uniformity. The basic principle of its preparation is to use the good fluidity of powder materials. Under the action of a step-change deformation, the pores between the powder particles completely disappear, achieving full densification. At the same time, the outer metal and the The inner layer metal forms a whole through excessive organization to realize the integration of solidification, organization and forming of powder components. The transition structure contains the steel sheathing between the layers when the metal powder is formed. Compared with the powder rolling method and the spray deposition method, the process flow is greatly shortened and the cost is reduced, thereby preparing a dense and fine recrystallized structure.

Compared with the preparation technology of powder superalloy ring components at home and abroad, the technical solution of the present invention has the following advantages:

(1) Utilizing the good fluidity of the powder, during the forming process of the bimetal composite bar, the integration of component curing and forming is realized, and the forming efficiency is improved;

(2) During the process of drilling the powder into the casing, the powder is subjected to temperature and pressure and continues to plastically deform, and the accumulated deformation properties meet the energy requirements of the powder particles from the interface bonding to the recrystallization nucleation and growth process;

(3) The process flow is simplified, the development cycle is shortened, the material utilization rate is improved, and the component manufacturing cost is reduced.

Description of drawings

Fig. 1 is the structural schematic diagram of the extrusion die in the technical solution of the present invention

Figure 2 is a schematic diagram of the internal structure of the composite bar in the technical solution of the present invention

Detailed ways

Below in conjunction with embodiment, the technical scheme of the present invention will be described in further detail:

Referring to Figures 1-2, the steps of the method for preparing a titanium-aluminum powder composite rod according to the present invention are as follows:

Step 1. Preparation of powder blanks

The powder blank consists of a powder jacket and a powder. The powder jacket is composed of four stainless steel cylindrical tube sets with the same height and different diameters, thereby forming four independent cavities, which are filled with metal titanium powder from the inside to the outside. Metal aluminum powder, metal titanium powder, metal aluminum powder, the core and the outward layered structure are four layers, and the diameter of the core is the same as the thickness of each outward layer;

Step 2. Prepare the extrusion device

The device includes a curing cavity and a forming cavity, the two parts are connected together and placed coaxially and horizontally, wherein:

The curing cavity includes an annular upper cavity 12 and an upper indenter 15. The upper indenter 15 is sleeved in the upper cavity 12 and is a transition fit, and an annular primary extrusion die 11 is connected to the rear end of the upper cavity 12. ;

The rear end of the primary extrusion die 11 is the forming cavity, which is the middle die cavity 10, the secondary extrusion die 5 and the lower die cavity 7 in sequence. transitional cooperation;

The curing cavity and the forming cavity are installed on the base 13 through the bracket 3, and the left hydraulic station 14 and the right hydraulic station 9 are respectively provided in the front and rear of the base 13 to supply the curing cavity and the forming cavity through the hydraulic pipe 1. components provide hydraulic actuation;

The components of the curing cavity and the forming cavity. The upper cavity 12, the primary extrusion die 11, the middle die cavity 10, the secondary extrusion die 5, and the lower die cavity 7 are provided between the insulation cotton 4 and the locking ring 16. connection fixed;

The secondary extrusion die 5 and the bracket 3 at the bottom of the lower die cavity 7 are mounted on the slide rail 8 on the base 13 and can independently move horizontally along the axial direction;

The inner hole of the secondary extrusion die 5 is tapered, and the difference between the maximum inner diameter and the minimum inner diameter is 1/20 of the length of the secondary extrusion die 5 .

The curing cavity and the forming cavity are made of steel material with a breaking strength exceeding 2000MPa;

Slide the powder blank and the upper indenter 15 into the upper die cavity 12 together, and position the left end face of the lower pressure rod 6 at the extrusion port of the lower die cavity 7;

Step 3. Powder and mold preheating

Heat the metal powder and the surrounding mold components to 300-500°C for heat preservation. The heat preservation time is calculated according to the following formula 1:

T _{holding time} = (L _{upper cavity diameter} + L _{upper pressure ring wall thickness} × 2) × 1.7min/mm Formula 1

Step 4. Powder solidification

After the holding time is over, the upper indenter 15 starts to act, and the speed is maintained between 17mm/s and 20mm/s until the pressure reaches 50-200MPa, and then the upper indenter 15 stops operating to obtain a solidified preform;

Step 5. Extrusion

The temperature of the solidified preform in the middle cavity 10 and the upper cavity 12 is raised to 500-700°C, and the solidified preform obtained in step 4 is extruded from the upper cavity 12 into the middle cavity 10 by the action of the upper indenter 15 . Inside, the speed is kept between 17mm/s and 20mm/s, and the extrusion ratio is between 1:1 and 2:1 to obtain a fully cured powder titanium-aluminum composite component;

Continue to push the fully solidified powder titanium-aluminum composite component to be extruded through the preheated secondary extrusion die 5, the preheating temperature is 700 ~ 1000 ℃, the speed is maintained between 17mm/s ~ 20mm/s, extrusion The out component is pierced through the center hole of the lower mold cavity 7, that is, the preparation of the titanium-aluminum powder composite rod is completed.

Claims (8)

1. The titanium-aluminum powder composite bar is characterized in that: the bar is in a layered structure from the core to the outside, the core is a cylinder of metal titanium, the outer layer is an annular metal aluminum layer, then an annular metal titanium layer, and the like, so that the titanium-aluminum composite bar is formed.

2. The titanium aluminum powder composite bar according to claim 1, wherein: the core part and the outward layered structures are both made of metal aluminum powder and metal titanium powder.

3. The titanium aluminum powder composite bar according to claim 1, wherein: the core and the outward layered structure are a total of four layers.

4. The titanium aluminum powder composite bar according to claim 1, wherein: the diameter of the core is the same as the thickness of the layers outward of the core.

5. An apparatus for preparing the titanium aluminum powder composite bar of claim 1, wherein: the device comprises a curing cavity and a forming cavity, wherein the two parts are connected together and coaxially and horizontally placed, and the device comprises:

the curing cavity comprises an annular upper cavity (12) and an upper pressure head (15), the upper pressure head (15) is sleeved in the upper cavity (12) and is in transition fit, and the rear end of the upper cavity (12) is connected with an annular first-stage extrusion die (11);

the rear end of the primary extrusion die (11) is a forming cavity which is sequentially a middle die cavity (10), a secondary extrusion die (5) and a lower die cavity (7), and a columnar lower pressure rod (6) is sleeved in a central hole of the lower die cavity (7) and is in transition fit;

the curing cavity and the forming cavity are arranged on a base (13) through a support (3), and a left hydraulic station (14) and a right hydraulic station (9) are respectively arranged in front of and behind the base (13) and provide hydraulic actuation for each part of the curing cavity and the forming cavity through hydraulic pipes (1);

heat insulation cotton (4) is arranged among the upper die cavity (12), the first-stage extrusion die (11), the middle die cavity (10), the second-stage extrusion die (5) and the lower die cavity (7) of the components of the curing die cavity and the forming die cavity and is fixedly connected through a lock catch ring (16).

6. The apparatus of claim 5, wherein: the two-stage extrusion die (5) and the bracket (3) at the bottom of the lower die cavity (7) are arranged on a slide rail (8) on a base (13) and can independently perform horizontal movement along the axial direction.

7. The apparatus of claim 5, wherein: the inner hole of the secondary extrusion die (5) is conical, and the difference between the maximum inner diameter and the minimum inner diameter is 1/20 of the length of the secondary extrusion die (5).

8. The apparatus of claim 5, wherein: the curing cavity and the forming cavity are made of steel materials with breaking strength exceeding 2000 MPa.

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