CN115502313A

CN115502313A - Preparation process of high-uniformity Ti-55 high-temperature titanium alloy large-size fine-grain blisk

Info

Publication number: CN115502313A
Application number: CN202210956837.8A
Authority: CN
Inventors: 杨久旭; 赵子博; 王清江; 孙昊; 张博华; 刘建荣; 陈志勇; 朱绍祥; 李文渊; 王磊; 刘建
Original assignee: Institute of Metal Research of CAS
Current assignee: Institute of Metal Research of CAS
Priority date: 2022-08-10
Filing date: 2022-08-10
Publication date: 2022-12-23

Abstract

The invention discloses a preparation process of a high-uniformity Ti55 high-temperature titanium alloy large-size fine-grain blisk, which comprises the steps of completing cogging forging of an alloy cast ingot at 1150-1250 ℃, then performing upsetting and drawing deformation on the obtained blank at 1015-1035 ℃ for 1 fire, cooling the forged blank by water, heating the blank to 890-920 ℃, keeping the temperature for 12-20 h, then heating the heated blank to 940-980 ℃ along with a furnace for forging, then performing upsetting and drawing deformation on the blank at 950-970 ℃ for 6-8 fire, and then forming the blank at 950-960 ℃ to obtain a forged blank; and finally, carrying out solid solution and aging heat treatment on the obtained forging stock to finally obtain the blisk forging blank. The process is suitable for preparing the blisk forge piece with the height of 700mm to 1200mm and the height of 60mm to 150mm, and the structure uniformity and the performance of the forge piece are superior to those of the traditional process.

Description

Preparation process of large-size fine-grain blisk made of high-uniformity Ti-55 high-temperature titanium alloy

Technical Field

The invention belongs to the field of new material processing, and particularly relates to a preparation process of a high-uniformity Ti-55 high-temperature titanium alloy large-size fine-grain blisk.

Background

The Ti-55 titanium alloy is based on Ti ₃ The near-alpha-shaped high-temperature titanium alloy designed according to the electron concentration rule of X phase precipitation has good heat strength and heat stability, the long-term working temperature can reach 550 ℃, the near-alpha-shaped high-temperature titanium alloy is mainly used for parts such as blisks, drums, blades and the like of high-pressure-section gas compressors of aircraft engines, and has good process plasticity at room temperature and high temperature.

With the increase of thrust-weight ratio of an aircraft engine, the working conditions of the air compressor are more complex, and steel and nickel-based high-temperature alloy are replaced by high-temperature titanium alloy with high specific strength, low density and high temperature resistance while the structural design of a blisk and a blisk ring is relied on, so that the purpose of reducing the structural weight is achieved.

Because Ti-55 has high alloying degree and is mainly alpha phase at room temperature, the deformation resistance is higher than that of the traditional two-phase titanium alloy such as TC4, TC11 and the like. The method causes great difficulty in forging the alloy blisk, particularly in forging and forming a large-size blisk, and the alloy blisk is easy to crack in the forging process, has poor hardenability and is difficult to obtain the structure and comprehensive performance meeting the requirements.

Disclosure of Invention

The invention aims to provide a preparation process of a high-uniformity Ti-55 high-temperature titanium alloy large-size fine-grain blisk, which comprises the following specific steps:

step 1) firstly heating an alloy ingot to 1050-1250 ℃, preserving heat for 15-35 h, and then discharging from a furnace for forging to finish 1 upsetting and drawing deformation; then the forging and drawing deformation is finished for 1 time after the furnace is returned and the temperature is kept for 1 to 2 hours, and the pressing deformation rate of each upsetting is 0.2s ^-1 ～0.08s ^-1 In the process, the single upsetting deformation is not less than 50%, and air cooling is carried out after forging to obtain a blank;

step 2) carrying out 1-time hot upsetting and drawing deformation on the blank obtained in the step 1) at the temperature of 1015-1035 ℃, wherein the upsetting press deformation rate is 0.2s ^-1 ～0.08s ^-1 The upsetting deformation is more than or equal to 50 percent, and water cooling is carried out after forging;

step 3) heating the blank to 890-920 ℃, preserving heat for 8-10 h, then heating to 940-980 ℃ along with the furnace for forging, and completing 1-time upsetting and drawing deformation; then the forging and drawing deformation is finished again after the furnace is returned and the temperature is kept for 1 to 2 hours, and the upsetting pressing rate is 0.05s ^-1 ～0.04s ^-1 The upsetting deformation is between 35 and 45 percent;

step 4) upsetting and drawing deformation of the blank are carried out for 5-7 times at 950-970 ℃, and the upsetting rate of each time is required to be 0.05s ^-1 ～0.04s ^-1 The deformation is between 30 and 50 percent, and the accumulated forging ratio is more than or equal to 3.3. The final forging temperature is not lower than 910 ℃;

step 5) forming the blank at 950-960 ℃, wherein the deformation rate of the forging blank per heating is required to be 0.005s ^-1 ～0.05s ^-1 The pressing amount is between 30 and 40 percent to obtain a forging stock;

and 6) carrying out solid solution and aging heat treatment on the forged blank obtained in the step 5), wherein the solid solution heat treatment system is as follows: t is a unit of _β Keeping the temperature for 1 to 3 hours at the temperature of between 10 and 30 ℃, and blowing the mixture out of the furnaceCooling or air cooling; the aging heat treatment comprises the following steps: keeping the temperature at 550-650 ℃ for 2-6 h, and then cooling in air.

The preferable scheme of the preparation process of the high-uniformity high-temperature titanium alloy large-size fine-grained structure blisk for the Ti-55 is that the high-temperature titanium alloy for the Ti-55 comprises the following components in percentage by mass: 5.0% -6.5%, sn:3.0% -5.0%, zr:2.0% -4.5%, mo:0.2% -1.5%, si: 0.2-1.0%, nb: 0.2-1.0%, ta:0.2% -1.5%, C:0.02 to 0.08 percent, and the balance of Ti and other inevitable impurity elements.

The preferred scheme of the preparation process of the high-uniformity high-temperature titanium alloy large-size fine-grained structure blisk for the Ti-55 is that the forming mode adopted in the step 5) is an isothermal or near isothermal forming process; when the isothermal or near isothermal die forging forming process is adopted, the die is heated to 0-60 ℃ below the heating temperature of the blank, and the deformation rate is 0.005s ^-1 ～0.05s ^-1 。

The invention has the beneficial effects that:

1) The diameter of the blisk forge piece prepared by the method is 700mm to 1200mm, the height of the blisk forge piece is 60mm to 150mm, the structure of each part of the forge piece is uniform, and the performance of the blisk forge piece is stable;

2) The tensile strength at room temperature of any part of the forging is not lower than 1000Mpa, the yield is not lower than 900Mpa, the elongation is not lower than 10.0%, and the face shrinkage is not lower than 20%. The elongation of the sample after 550 ℃/100h heat exposure is not less than 8.0 percent, and the surface shrinkage is not less than 15 percent. The tensile strength of the alloy at 550 ℃ is not lower than 650Mpa, the yield is not lower than 510Mpa, the elongation is not lower than 15.0 percent, and the area shrinkage is not lower than 25 percent.

Compared with the traditional process, the process is suitable for preparing the large-size blisk forge piece, and the structure uniformity and the metallurgical quality stability of the forge piece are obviously improved compared with the traditional process. The method has the advantages of simple operation, short flow, high stability and suitability for industrial production.

Drawings

FIG. 1 is a high magnification organization picture near the surface of a forging prepared in example 1;

FIG. 2 is a photograph of a high magnification structure of the center of the forging prepared in example 1;

FIG. 3 is a photograph of a high magnification structure near the surface of the forging produced in example 2;

FIG. 4 is a photograph of a high magnification texture of the center of the forging prepared in example 2;

FIG. 5 is a schematic view of die forgings of examples 3 and 4;

FIG. 6 is a high magnification microstructure picture of the rim of the die forged part prepared in example 3;

FIG. 7 is a high magnification organization picture of a spoke plate of the die forging prepared in example 3;

FIG. 8 is a high power texture picture of the die forging hub prepared in example 3;

FIG. 9 is a high power texture picture of the rim of the die forged part prepared in example 3;

FIG. 10 is a high magnification organization picture of a spoke plate of the die forging prepared in example 3;

FIG. 11 is a high magnification organization chart of the die forging hub prepared in example 3.

Detailed Description

Example 1:

the size of the Ti55 alloy ingot selected in the embodiment is 600mm in diameter and 1500mm in length, and the ingot comprises the following chemical components: ti-5.45Al-3.33Sn-2.95Zr-0.65Mo-0.34Si-0.39Ta-0.37Nb, beta transition temperature is 1005 ℃;

step 1) heating a straight alloy ingot to 1100 ℃, preserving heat for 24 hours, discharging from a furnace, and forging to finish 1-time upsetting and drawing deformation; then the blank is returned to the furnace and is kept warm for 1.5h, and then 1 upsetting and drawing deformation are finished, and the pressing deformation rate of each upsetting is 0.1s ^-1 The single upsetting deformation is not less than 50 percent;

step 2) carrying out upsetting and drawing deformation on the blank obtained in the step 1) for 1 heating time at 1025 ℃, wherein the pressing deformation rate is 0.1s ^-1 Upsetting deformation is 52%, forging ratio is 3.4, and water cooling is carried out after forging;

step 3) heating the blank to 910 ℃, preserving heat for 10h, then heating to 960 ℃ along with the furnace for upsetting and drawing deformation, then returning to the furnace and preserving heat for 2h for carrying out upsetting and drawing deformation again, wherein the upsetting deformation rate is 0.04s ^-1 The deformation is 39%, and air cooling is carried out after forging;

step 4) heating the blank at 970 ℃ for 3 timesUpsetting and drawing deformation, the upsetting deformation rate is 0.04s ^-1 ～0，05s ^-1 The deformation is between 40 and 43 percent, the accumulated forging ratio of each fire is between 3.3 and 3.7, and the finish forging temperature is above 920 ℃;

step 5) upsetting and drawing the blank for 4 times at 950 ℃ to deform; the upsetting deformation rate is 0.04s ^-1 ～0，05s ^-1 The deformation is between 40 and 42 percent, and the accumulated forging ratio of each fire is between 3.3 and 3.5; the final forging temperature is above 910 ℃;

step 6) blanking by using a sawing machine according to the design size of the final forged piece, and forming the blank at 955 ℃, wherein the forming pressing deformation is 40% to obtain a forged blank;

and 7) carrying out solid solution and aging heat treatment on the forged blank finally, wherein the solid solution heat treatment system is as follows: 985. keeping the temperature for 2 hours, and cooling in air after discharging; the aging heat treatment comprises the following steps: keeping the temperature at 600 ℃ for 6h, and then air-cooling; and finally, polishing the surface to obtain a forging with the diameter of 1000mm and the height of 150 mm.

Example 2:

this example is a comparative example of example 1, and the ingot size, chemical composition, and β -transus temperature of the alloy selected were exactly the same as those of example 1.

In the embodiment, in the step 3, the forging stock is directly heated to 960 ℃ for upsetting, drawing and deforming, and other steps are completely the same as those in the embodiment 1, so that the forging with the diameter of 1000mm and the height of 150mm is finally obtained.

The forgings of the embodiment 1 and the embodiment 2 are analyzed and compared in structure and mechanical property. The high power structure of the forging of the embodiment 1 is a two-state structure, the primary alpha content is about 10%, the primary alpha content is distributed in a dispersing way, the primary beta grain size is fine and uniform, and the structures at all positions have higher consistency (figures 1 and 2). The room-temperature tensile strength of the forge piece is not lower than 1030MPa, the 550-DEG C tensile strength is more than 670MPa, and the forge piece has good plasticity at room temperature and high temperature; after the sample is subjected to heat exposure at 550 ℃/100h, the room temperature strength and plasticity are not obviously reduced, and the thermal stability of the forge piece is good. The high-power structure of the forging in example 2 is a two-state structure, the primary alpha content is about 10%, the original beta grain sizes of different positions of the forging are significantly different, and the primary alpha phase is not uniformly distributed (fig. 3 and 4). Compared with the embodiment 1, the mechanical property of the forging is lower, and the difference of the mechanical properties at different positions is relatively larger.

TABLE 1 tensile Properties of the forgings of example 1

Table 2 thermal stability in example 1

TABLE 3 tensile Properties of the forgings of example 2

Table 4 thermal stability in example 2

Example 3:

the size of the Ti55 alloy ingot selected in the embodiment is 600mm in diameter and 1500mm in length, and the ingot comprises the following chemical components: ti-5.56Al-3.39Sn-3.01Zr-0.61Mo-0.30Si-0.35Ta-0.41Nb, beta transition temperature is 1007 DEG C

Step 1) firstly heating an alloy ingot to 1100 ℃, preserving heat for 24 hours, and then discharging from a furnace for forging to finish 1-time upsetting and drawing deformation; then the forging and drawing deformation is finished for 1 time after the furnace is returned and the temperature is kept for 1.5 hours, and the pressing deformation rate of each upsetting is 0.1s ^-1 Single upsetting deformation is not less than 50%, and air cooling is carried out after forging to obtain a blank;

step 2) carrying out upsetting and drawing deformation on the blank obtained in the step 1) for 1 heating time at 1030 ℃, wherein the upsetting deformation is 51 percent, and the deformation rate is 0.1s ^-1 The forging ratio is 3.4, and water cooling is carried out after forging;

step 3) heating the blank to 900 ℃, preserving heat for 9h and thenHeating the furnace to 970 ℃ for upsetting and drawing deformation for 1 fire, then returning the furnace to the furnace and preserving heat for 2 hours, and completing upsetting and drawing deformation for the second time, wherein the upsetting deformation is 40 percent, and the deformation rate is 0.05s ^-1 Air cooling after forging;

step 4) heating the blank to 970 ℃ to perform upsetting and drawing deformation for 7 times, wherein the upsetting pressing rate of each time is 0.04s ^-1 The pressing amount is between 39% and 42%, and the forging ratio is between 3.5 and 3.8. The final forging temperature is above 910 ℃;

step 5) according to the design of the forge piece, adopting sawing blanking and adopting a near isothermal molding process to heat the die to 890 ℃, heat the forging stock to 950 ℃ and have the deformation rate of 0.01s ^-1 Performing air cooling after forging to obtain a cake blank of the die forging, wherein the deformation is 40%;

and 6: carrying out solid solution and aging heat treatment on the forged blank, wherein the solid solution heat treatment system is as follows: keeping the temperature at 985 ℃ for 2 hours, and cooling in air after discharging; the aging heat treatment comprises the following steps: keeping the temperature at 600 ℃ for 6 hours, and then cooling in air. And finally, polishing the surface to obtain a forged piece with the diameter of 1200mm and the height of 100 mm.

Example 4:

this example is a comparative example to example 3, and the ingot size, chemical composition, beta transus temperature and the alloy ingot selected are all the same as in example 3.

In the embodiment, in the step 3, the forging stock is directly heated to 960 ℃ for upsetting, drawing and deforming, and other steps are completely the same as those in the embodiment 3, so that the forging with the diameter of 1200mm and the height of 100mm is finally obtained.

FIG. 5 is a schematic cross-sectional view of forgings of embodiments 3 and 4. The forgings of the embodiments 3 and 4 are analyzed and compared in structure and mechanical property, the high power structure of the forgings of the embodiments 3 is a two-state structure, the primary alpha content is about 10%, the two-state structure is distributed in a dispersion shape, the primary beta crystal grains are fine and uniform in size, and the structures at all positions are not obviously different (fig. 6-8). The tensile strength of the forged piece at room temperature is more than 1020MPa, the tensile strength of the forged piece at 550 ℃ is more than 670MPa, and the forged piece has good plasticity at room temperature and at high temperature; after the sample is subjected to heat exposure at 550 ℃/100h, the room temperature strength and plasticity are not obviously reduced, and the thermal stability of the forge piece is good. The forging of example 4 had a high-power structure of a two-state structure, and the primary α distribution states at different positions were significantly different from each other, and the primary β crystal grains were relatively coarse and uneven (fig. 9 to 11). The mechanical properties of different positions of the forged piece are greatly different, and the overall mechanical property of the forged piece is lower than that of the forged piece in embodiment 3.

TABLE 5 tensile Properties of the forgings of example 3

Table 6 thermal stability in example 4

TABLE 7 tensile Properties of the forgings of example 4

Table 8 thermal stability in example 3

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation process of a high-uniformity Ti-55 high-temperature titanium alloy large-size fine-grain blisk is characterized by comprising the following specific steps:

step 1) firstly heating a Ti-55 high-temperature titanium alloy ingot to 1050-1250 ℃, preserving heat for 15-35 h, discharging and forging to finish 1 upsetting and drawing deformation; then the blank is returned to the furnace and is kept warm for 1 to 2 hours, and then 1 upsetting and drawing deformation are finished, and each upsetting and pressing deformationForm rate of 0.2s ^-1 ～0.08s ^-1 During forging, the single upsetting deformation is not less than 50%, and air cooling is performed after forging to obtain a blank;

step 3) heating the blank to 890-920 ℃, preserving heat for 8-10 h, and then heating to 940-980 ℃ along with the furnace for forging to complete 1-time upsetting and drawing deformation; then the forging and drawing deformation is finished again after the furnace is returned and the temperature is kept for 1 to 2 hours, and the upsetting pressing rate is 0.05s ^-1 ～0.04s ^-1 The upsetting deformation is between 35 and 45 percent;

step 5) forming the blank at 950-960 ℃, wherein the deformation rate of the forging blank per firing time is required to be 0.005s ^-1 ～0.05s ^-1 The pressing amount is between 30 and 40 percent to obtain a forging stock;

and 6) carrying out solid solution and aging heat treatment on the forged blank obtained in the step 5), wherein the solid solution heat treatment system is as follows: t is _β Keeping the temperature for 1 to 3 hours at the temperature of between 10 and 30 ℃, and carrying out air cooling or air cooling after discharging; the aging heat treatment comprises the following steps: keeping the temperature of 550-650 ℃ for 2-6 h, and then cooling in air.

2. The process for preparing a high uniformity Ti-55 high temperature titanium alloy large size fine grain blisk as claimed in claim 1, wherein: the Ti-55 high-temperature titanium alloy ingot comprises the following components in percentage by weight: 5.0% -6.5%, sn:3.0% -5.0%, zr:2.0% -4.5%, mo:0.2% -1.5%, si: 0.2-1.0%, nb: 0.2-1.0%, ta:0.2% -1.5%, C:0.02 to 0.08 percent of the total weight of the alloy, and the balance of Ti and other inevitable impurity elements.

3. The process for preparing a high uniformity Ti-55 high temperature titanium alloy large size fine grain blisk as claimed in claim 2, wherein: the blisk forged piece with the diameter of 600mm to 1200mm and the height of 60mm to 150mm is prepared by adopting the process.

4. The process for preparing a high-uniformity Ti-55 high-temperature titanium alloy large-size fine-grain blisk as claimed in claim 1, wherein the process comprises the following steps: the forming mode adopted in the step 5) is an isothermal or near isothermal forming process; when the isothermal or near isothermal die forging forming process is adopted, the die is heated to 0-60 ℃ below the heating temperature of the blank, and the deformation rate is 0.005s ^-1 ～0.05s ^-1 。