WO2025060796A1 - Tzm alloy for large-size isothermal forging die, manufacturing process therefor and use thereof - Google Patents

Abstract

The present invention relates to the technical field of alloy manufacture, and specifically provides a TZM alloy for a large-size isothermal forging die, a manufacturing process therefor and the use thereof. The present invention uses a powder metallurgy + hot isostatic pressing + forging process to manufacture TZM alloy, provides complete process parameters and processing solutions, and can manufacture TZM alloy for large-size isothermal forging dies. Using the process can manufacture high-density, high-hardness and high-strength TZM alloy blanks.

Description

TZM alloy for large-size isothermal forging dies and its preparation process and use Technical Field

The invention relates to the technical field of alloy preparation, and specifically provides a TZM alloy for a large-size isothermal forging die, and a preparation process and application thereof.

Background Art

With the rapid development of my country's aerospace technology, aircraft engines, as the core of aviation weapons and equipment, need to have a higher thrust-to-weight ratio to carry a larger load, and hot-end components need to withstand higher temperature loads, such as combustion chambers, turbine disks, blades, etc., which requires high-temperature structural materials to have better performance. Due to the characteristics of high-temperature alloys with a narrow forging temperature range and high deformation resistance, it is necessary to make them plastically deformed within a certain forging temperature range. At present, key components of aircraft engines such as turbine disks are mostly forged by isothermal forging. With the continuous upgrading of aircraft engines, a higher engine thrust-to-weight ratio is the main development goal, which requires the materials of hot-end components of aircraft engines to have higher thermal fatigue resistance. For example, TiAl intermetallic compounds are a lightweight structural material with good development prospects, and their isothermal forging temperature needs to be above 1100°C. The development of hot-end component materials puts higher requirements on isothermal forging die materials. In order to develop isothermal forging die materials that can be used at higher temperatures, researchers focus on high-melting-point refractory metals. Metallic molybdenum is one of the refractory metals with a melting point of up to 2620°C, ranking sixth among natural elements. It has good room temperature processing performance. Therefore, molybdenum and its alloys are considered to be used in the preparation of large-size isothermal forging dies.

TZM alloy has a high melting point (2617℃), excellent high temperature strength, high stiffness, low thermal expansion coefficient, high thermal conductivity, and good creep resistance, so it is suitable for the development of large-size vacuum isothermal forging die materials. At present, Western countries led by the United States use TZM alloy for vacuum isothermal forging die materials above 1000℃. In order to keep up with the international advanced level and improve my country's independent research and development and production capabilities, it is necessary to quickly carry out relevant research on TZM alloys for isothermal forging dies and explore the organization of TZM alloys during hot processing. The law of evolution.

Hot isostatic pressing can repair the defects of powder sintered TZM alloy, improve the density of powder sintered TZM alloy, and improve the processing performance of TZM alloy, but it has limited effect on the microstructure regulation of TZM alloy. Hot deformation can further reduce the hole defects in the billet, refine the grains, introduce high-density substructure strengthening, and improve material properties. At present, the research on hot deformation of TZM alloys in China is mainly based on rolling, and TZM alloys are mostly in the form of plates, which will limit the size of alloy products. There are few reports on the hot deformation research of TZM alloys for large-size isothermal forging dies, and there are few reports on the evolution of microstructure and properties during the forging process of TZM alloys.

In view of this, the present invention is proposed.

Summary of the invention

The first object of the present invention is to provide a preparation process of TZM alloy for large-size isothermal forging dies.

The second object of the present invention is to provide a TZM alloy prepared by the above preparation process.

A third object of the present invention is to provide uses of the TZM alloy.

In order to achieve the above object, the present invention adopts the following technical solution:

A preparation process of a TZM alloy for a large-size isothermal forging die comprises the following steps:

S1: ball milling, cold isostatic pressing and sintering of TZM alloy powder in sequence to obtain PM state TZM alloy billet;

The pressure of cold isostatic pressing is 140-160 MPa, and the sintering condition is 2000-2100℃ for 2.5-3.5h;

S2: hot isostatic pressing the PM state TZM alloy billet in S1 to obtain a PM+HIP state TZM alloy billet;

The conditions of hot isostatic pressing are 1200-1400°C and 120-140 MPa for 2-3 hours;

S3: Forging the PM+HIP TZM alloy billet in S2 to obtain a large-size isothermal forging die TZM alloy;

The forging conditions are as follows: the starting forging temperature is set at 1300-1500°C, the final forging temperature is set at 1100-1200°C, the deformation amount during the forging process is controlled to be ≥40%, and then the TZM alloy ingot is returned to the high-temperature furnace to continue heating to the forging temperature, and after the forging is completed, it is cooled to room temperature with the furnace.

Furthermore, the TZM alloy powder in S1 includes: TiH2 _powder 0.45% to 0.65% with a particle size of 2 to 5 μm; ZrH2 _powder 0.10% to 0.15% with a particle size of 2 to 5 μm; C powder 0.04% to 0.08% with a particle size of 1 to 2 μm; and the rest is molybdenum powder with a particle size of 2 to 5 μm.

Furthermore, the ball milling conditions in S1 include: ball milling speed of 240-260 r/min, ball-to-material ratio of 2:1, and ball milling time of 2 h.

Furthermore, hydrogen is used as the protective gas during sintering in S1.

Furthermore, the hot isostatic pressing conditions in S2 are as follows: stainless steel is used as the sheath material, placed in a degassing furnace for evacuation and welding of the sheath, then placed in a hot isostatic press, inert gas is used as the pressure gas, the heating temperature is 1200-1400°C, the pressure is 120-140MPa, and after hot isostatic pressing, it is cooled to room temperature with the furnace.

Furthermore, the inert gas is argon.

Furthermore, the heating temperature is 1300° C. and the pressure is 130 MPa.

Furthermore, the starting temperature of forging in S3 is set to 1400°C, and the final forging temperature is set to 1150°C.

The TZM alloy prepared by the above preparation process.

The above TZM alloy is used in the preparation of large-size isothermal forging dies.

Compared with the prior art, the technical effects of the present invention are:

(1) The present invention adopts powder metallurgy + hot isostatic pressing + forging process to prepare TZM alloy, provides complete process parameters and processing scheme, and can realize the preparation of TZM alloy for large-size isothermal forging die. The alloy density reaches 98.5%, the average grain size is 51μm, the hardness reaches 259HV, and the tensile strength at 600℃ is 672MPa. The tensile strength at 1200℃ is 398MPa. The process can be used to prepare TZM alloy billets with high density, high hardness and high strength.

(2) The present invention uses HIP to repair and eliminate PM state void defects, improves alloy density, and combines with forging technology to improve the comprehensive performance of the alloy;

(3) The present invention adopts forging as a thermal deformation method to effectively improve the TZM alloy The density and high temperature strength of the metal, a large number of substructures are formed inside the grains after forging, which plays a role in deformation strengthening.

(4) The present invention adopts powder metallurgy + hot isostatic pressing + forging process. Compared with the conventional rolling method, the TZM alloy billet obtained by this process is more suitable as a large-size isothermal forging die material.

BRIEF DESCRIPTION OF THE DRAWINGS

The various technical features of the present invention and the relationship between them are further explained below with reference to the accompanying drawings. The accompanying drawings are exemplary, and some technical features are not shown in actual proportion. In addition, some drawings may omit technical features that are commonly used in the technical field to which the present invention belongs and are not essential for understanding and implementing the present invention, or additionally show technical features that are not essential for understanding and implementing the present invention. In other words, the combination of the various technical features shown in the accompanying drawings is not used to limit the present invention. In addition, in the full text of the present invention, the same figure numerals refer to the same content. The specific description of the drawings is as follows:

FIG1 is a photograph of the microstructure and grain size of a PM-state TZM alloy billet in Example 1 of the present invention;

FIG2 is a photograph of the microstructure and grain size of the PM+HIP TZM alloy billet in Example 1 of the present invention;

FIG. 3 shows the microstructure and grain size of the PM+HIP+F state TZM alloy billet in Example 1 of the present invention.

DETAILED DESCRIPTION

The specific embodiments of the present invention are described in detail below.

Titanium-zirconium-molybdenum alloy (TZM alloy) is an alloy formed by doping a certain amount of Ti (titanium) and Zr (zirconium) with molybdenum as the matrix. The alloy content is generally less than 1%. TZM alloy has excellent high temperature performance, is not prone to recrystallization, and has relatively good processability at room temperature. TZM alloy has good welding performance and is currently the most widely used molybdenum-based alloy.

Powder metallurgy (PM) process consists of powder preparation, ball milling, compacting and sintering, and is currently the main method for preparing molybdenum-based alloys. The powder metallurgy process has low sintering temperature and is not very demanding on equipment. The requirements are relatively low, and the production efficiency is high, the cost is low, there is no component segregation, and near-net forming can be achieved. By using powder metallurgy technology, the material composition ratio and process parameters are precisely adjusted to obtain the appropriate porosity, and the interaction between the materials can be used to produce composite materials with a variety of properties.

Hot isostatic pressing (HIP) usually refers to placing a workpiece (billet, casting, etc.) inside a closed container, which is filled with a pressure medium, usually nitrogen or argon. Under the combined action of high temperature and high pressure, the density of the alloy obtained is higher than that of pressureless sintering. The heating temperature is generally 0.7 to 0.9 times the melting point.

Forging (F) is a processing method that applies pressure to metal billets and uses the principle of plastic deformation to give the billets certain mechanical properties, shapes and sizes. The use of appropriate forging processes can achieve deformation strengthening effects on TZM alloys and play a certain role in eliminating hole defects in alloy ingots.

The alloy prepared by the powder metallurgy process has defects such as pores, shrinkage cavities and cracks inside, which will have a great impact on the performance of the material and is not suitable for high-temperature isothermal forging dies. Although the above problems can be partially overcome by using large deformation and high deformation speed, the slab used is not suitable for preparing large-size dies. However, the present invention further performs hot isostatic pressing and forging on the basis of preparing TZM alloy by powder metallurgy, improves defects such as pores and cracks inside the alloy, improves the density of the alloy, and improves the overall performance.

Specifically, the present invention provides a preparation process of a TZM alloy for a large-size isothermal forging die, characterized in that it comprises the following steps:

S1: ball milling, cold isostatic pressing and sintering of TZM alloy powder in sequence to obtain PM state TZM alloy billet;

The pressure of cold isostatic pressing is 140-160 MPa, and the sintering conditions are sintering at 2000-2100°C for 2.5-3.5 hours.

S2: hot isostatic pressing the PM state TZM alloy billet in S1 to obtain a PM+HIP state TZM alloy billet;

The conditions of hot isostatic pressing are 1200-1400°C and 120-140MPa for 2-3h.

S3: Forging the PM+HIP TZM alloy billet in S2 to obtain a large-size isothermal forging die TZM alloy;

The forging conditions are as follows: the starting forging temperature is set at 1300-1500°C, the final forging temperature is set at 1100-1200°C, the deformation amount during the forging process is controlled to be ≥40%, and then the TZM alloy ingot is returned to the high-temperature furnace to continue heating to the forging temperature, and after the forging is completed, it is cooled to room temperature with the furnace.

In some embodiments, the TZM alloy powder in S1 includes: TiH2 _powder 0.45% to 0.65%, with a particle size of 2 to 5 μm; ZrH2 _powder 0.10% to 0.15%, with a particle size of 2 to 5 μm; C powder 0.04% to 0.08%, with a particle size of 1 to 2 μm; and the rest is molybdenum powder with a particle size of 2 to 5 μm.

In some embodiments, the ball milling conditions in S1 include: the ball milling conditions include: ball milling speed 240-260r/min, ball-to-material ratio 2:1, and ball milling time 2h.

In some embodiments, hydrogen is used as a protective gas during sintering in S1. Hydrogen plays two roles in powder sintering. One is to isolate the air and prevent oxidation, because molybdenum will oxidize at around 400°C, and the oxidation rate will greatly increase above 600°C. Hydrogen protection prevents the formation of molybdenum trioxide ( _MoO3 ) volatilization and pollution of equipment and environment. The second role of hydrogen is to reduce the partially oxidized _MoO3 on the surface of the alloy blank to Mo.

The main purpose of hot isostatic pressing is to further improve the density of PM state TZM alloy. In some embodiments, the hot isostatic pressing conditions in S2 are: stainless steel is used as the sheath material, placed in a degassing furnace for evacuation and welding of the sheath, then placed in a hot isostatic press, inert gas is used as the pressure gas, the heating temperature is 1200-1400°C, the pressure is 120-140MPa, and the furnace is cooled to room temperature after hot isostatic pressing. Among them, the inert gas is preferably argon, the heating temperature is preferably 1300°C, and the pressure is preferably 130MPa.

In some embodiments, forging adopts a recrystallization zone + non-recrystallization zone composite controlled deformation process, with the starting temperature set at 1400°C and the final forging temperature set at 1150°C. The TZM alloy ingot is then returned to the high-temperature furnace and continued to be heated to a temperature of 1400-1500°C, and the deformation amount is controlled to be ≥40% during the entire forging process. The deformation in the recrystallization zone refines the alloy grain size, and the deformation in the non-recrystallization zone enhances the substructure density and improves the substructure strengthening effect.

Example 1

This example uses TZM alloy powder manufactured by Jinduicheng Company as the original alloy powder.

Preparation of original alloy powder: Molybdenum oxide powder was mechanically crushed and ball-milled. Ultrafine molybdenum oxide powder is prepared, and then MoO ₃ is reduced with H ₂ to obtain high-purity molybdenum powder with a particle size of about 2 to 5 μm. After adding appropriate amounts of TiH ₂ , ZrH ₂ and C powder according to the ratio (TiH 2 powder 0.52%, particle size 2.0 μm; ZrH 2 powder 0.12%, particle size 2.2 μm; C powder 0.05 _% , particle size 1.0 μm; the rest is molybdenum powder, particle size 2.5 _μm ), TZM alloy powder is obtained through a powder mixing process.

Powder metallurgy (PM) process: The original TZM alloy powder is ball milled, and then cold isostatic pressing is performed with a pressure setting of 150 MPa. The cold isostatic pressing blank is then sintered with a powder sintering temperature set at 2050°C and a sintering time of 3 hours to obtain a PM state TZM alloy blank. Hydrogen is used as a protective atmosphere and a reducing atmosphere during the sintering process.

The microstructure and grain size of the PM state TZM alloy billet are shown in Figure 1, where (a) is a picture of the PM state TZM alloy billet before corrosion, and the density of the PM state TZM alloy is 94.2%. (b) is an OM photo of the powder metallurgy billet after corrosion. It can be seen that the grain boundaries are obvious and the grains remain equiaxed. The average grain size calculated by the intercept method is 48μm.

Hot isostatic pressing (HIP) process: The PM state TZM alloy billet is further subjected to hot isostatic pressing. The billet is covered with stainless steel material, placed in a degassing furnace for evacuation, and the cover is welded. It is then placed in a hot isostatic press. The heating temperature is set to 1300°C, the pressure is set to 130MPa, the hot isostatic pressing time is 2.5h, and argon is used as the pressure gas in the sintering process. After sintering, it is cooled to room temperature with the furnace to obtain a PM+HIP state TZM alloy billet.

The microstructure and grain size of the PM+HIP TZM alloy billet are shown in Figure 2, where (a) is a picture of the PM+HIP TZM alloy billet before corrosion. The density of the PM+HIP state is 95.6%, which is slightly improved compared to before HIP. (b) is a metallographic photograph after corrosion, and the grains still remain equiaxed. The average grain size of the PM+HIP TZM alloy is 50μm, which is very close to that of the PM state.

Forging (F) process: the starting forging temperature is set at 1400°C, the final forging temperature is set at 1150°C, the deformation amount during the forging process is about 40%, and then the TZM alloy ingot is returned to the high-temperature furnace to continue heating to the forging temperature. After sintering, it is cooled to room temperature with the furnace to obtain a PM+HIP+F state TZM alloy billet.

The microstructure and grain size of the PM+HIP+F state TZM alloy blank are shown in Figure 3, where (a) is a microstructure photo before corrosion and (b) is a metallographic photo after corrosion. The density of the PM+HIP+F state TZM alloy reaches 98.5%, the average grain size is 51μm, and the hardness reaches 259HV. The tensile strength at 600℃ is 672MPa, and the elongation after fracture is 10%. The tensile strength at 1200℃ is 396MPa.

Comparative Example 1PM Process

In this comparative example, TZM alloy powder manufactured by Jinduicheng Company was used as the original alloy powder.

Preparation of original alloy powder: Mechanically crush and ball-mill the molybdenum oxide powder to obtain ultrafine molybdenum oxide powder, and then use H ₂ to reduce MoO ₃ to obtain high-purity molybdenum powder with a particle size of about 2 to 5 μm. After adding appropriate amounts of TiH ₂ , ZrH ₂ and C powder according to the ratio, the TZM alloy powder is obtained through a powder mixing process.

Powder metallurgy (PM) process: The original TZM alloy powder is ball milled, and then cold isostatic pressing is performed with a pressure setting of 150 MPa. The cold isostatic pressing blank is then sintered with a powder sintering temperature set at 2050°C and a sintering time of 3 hours to obtain a PM state TZM alloy blank. Hydrogen is used as a protective atmosphere and a reducing atmosphere during the sintering process.

The density of PM state TZM alloy reaches 94.2%, the average grain size is 48μm, the hardness reaches 169HV, the room temperature tensile strength is 426MPa, the elongation after fracture is 3.5%, the tensile strength at 600℃ is 398MPa, and the elongation after fracture is 19%.

Comparative Example 2PM+HIP Process

In this comparative example, TZM alloy powder manufactured by Jinduicheng Company was used as the original alloy powder.

Preparation of original alloy powder: Mechanically crush and ball-mill the molybdenum oxide powder to obtain ultrafine molybdenum oxide powder, and then use H ₂ to reduce MoO ₃ to obtain high-purity molybdenum powder with a particle size of about 2 to 5 μm. After adding appropriate amounts of TiH ₂ , ZrH ₂ and C powder according to the ratio, the TZM alloy powder is obtained through a powder mixing process.

Powder metallurgy (PM) process: The original TZM alloy powder is ball milled, and then cold isostatic pressing is performed with a pressure setting of 150 MPa. The cold isostatic pressing blank is then sintered with a powder sintering temperature set at 2050 °C and a sintering time of 3 h to obtain a PM state. TZM alloy billet. Hydrogen is used as protective atmosphere and reducing atmosphere during sintering.

Hot isostatic pressing (HIP) process: The PM state TZM alloy billet is further subjected to hot isostatic pressing. The billet is covered with stainless steel material, placed in a degassing furnace for evacuation, and the cover is welded. It is then placed in a hot isostatic press. The heating temperature is set to 1300°C, the pressure is set to 130MPa, the hot isostatic pressing time is 2.5h, and argon is used as the pressure gas in the sintering process. After sintering, it is cooled to room temperature with the furnace to obtain a PM+HIP state TZM alloy billet.

The density of PM+HIP TZM alloy reaches 95.6%, the average grain size is 50μm, the hardness is 172HV, the room temperature tensile strength of PM+HIP TZM alloy is 448MPa, which is about 22MPa higher than that of PM TZM alloy, and the average elongation after fracture of PM+HIP TZM alloy at room temperature is 4.0%. The tensile strength at 600℃ is 400MPa, and the elongation after fracture is 19%, which is significantly lower than that of PM+HIP+F state.

Comparative Example 3PM+F Process

This comparative example uses TZM alloy powder manufactured by Jinduicheng Company as the original alloy powder.

Preparation of original alloy powder: Mechanically crush and ball-mill the molybdenum oxide powder to obtain ultrafine molybdenum oxide powder, and then use H ₂ to reduce MoO ₃ to obtain high-purity molybdenum powder with a particle size of about 2 to 5 μm. After adding appropriate amounts of TiH ₂ , ZrH ₂ and C powder according to the ratio, the TZM alloy powder is obtained through a powder mixing process.

Powder metallurgy (PM) process: The original TZM alloy powder is ball milled, and then cold isostatic pressing is performed with a pressure setting of 150 MPa. The cold isostatic pressing blank is then sintered with a powder sintering temperature set at 2050°C and a sintering time of 3 hours to obtain a PM state TZM alloy blank. Hydrogen is used as a protective atmosphere and a reducing atmosphere during the sintering process.

Forging (F) process: the starting forging temperature is set at 1400°C, the final forging temperature is set at 1150°C, the deformation amount during the forging process is about 40%, and then the TZM alloy ingot is returned to the high-temperature furnace to continue heating to the forging temperature. After sintering, it is cooled to room temperature with the furnace to obtain a PM+F state TZM alloy billet.

The tensile strength of PM+F state TZM alloy at 600℃ is 620MPa, and the elongation after fracture is 7%. The strength and plasticity are lower than those of PM+HIP+F state alloy.

Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. If there is any inconsistency, the meaning described in the present invention or the meaning derived from the content recorded in the present invention shall prevail. In addition, the terms used in this description are only for the purpose of describing the embodiments of the present invention and are not intended to limit the present invention.

Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may also include more other equivalent embodiments without departing from the technical concept of the present invention, all of which belong to the protection scope of the present invention.

Claims (10)

A preparation process of a TZM alloy for a large-size isothermal forging die, characterized in that it comprises the following steps: S1: ball milling, cold isostatic pressing and sintering of TZM alloy powder in sequence to obtain PM state TZM alloy billet; The pressure of cold isostatic pressing is 140-160 MPa, and the sintering condition is 2000-2100℃ for 2.5-3.5h; S2: hot isostatic pressing the PM state TZM alloy billet in S1 to obtain a PM+HIP state TZM alloy billet; The conditions of hot isostatic pressing are 1200-1400°C and 120-140 MPa for 2-3 hours; S3: Forging the PM+HIP TZM alloy billet in S2 to obtain a large-size isothermal forging die TZM alloy; The forging conditions are as follows: the starting forging temperature is set at 1300-1500°C, the final forging temperature is set at 1100-1200°C, the deformation amount during the forging process is controlled to be ≥40%, and then the TZM alloy ingot is returned to the high-temperature furnace to continue heating to the forging temperature, and after the forging is completed, it is cooled to room temperature with the furnace. The preparation process according to claim 1 is characterized in that the TZM alloy powder in S1 includes: _TiH2 powder 0.45% to 0.65% with a particle size of 2 to 5 μm; ZrH2 _powder 0.10% to 0.15% with a particle size of 2 to 5 μm; C powder 0.04% to 0.08% with a particle size of 1 to 2 μm; and the rest is molybdenum powder with a particle size of 2 to 5 μm. The preparation process according to claim 1 is characterized in that the ball milling conditions in S1 include: ball milling speed 240-260r/min, ball-to-material ratio 2:1, and ball milling time 2h. The preparation process according to claim 1 is characterized in that hydrogen is used as the protective gas during sintering in S1. The preparation process according to claim 1 is characterized in that the conditions for hot isostatic pressing in S2 are: stainless steel is used as the sheath material, placed in a degassing furnace for evacuation and welding of the sheath, and then placed in a hot isostatic press, inert gas is used as the pressure gas, the heating temperature is 1200-1400°C, the pressure is 120-140MPa, and after hot isostatic pressing, it is cooled to room temperature with the furnace. The preparation process according to claim 5, characterized in that the inert gas is argon. The preparation process according to claim 5 is characterized in that the heating temperature is 1300°C and the pressure is 130MPa. The preparation process according to claim 1 is characterized in that the starting temperature of forging in S3 is set to 1400°C and the final forging temperature is set to 1150°C. The TZM alloy prepared by the preparation process according to any one of claims 1 to 8. Use of the TZM alloy described in claim 9 in preparing large-size isothermal forging dies.