CN115502314A - Preparation process of high-uniformity TC4 titanium alloy large-size fine-grain blisk - Google Patents

Abstract

The invention discloses a preparation process of a high-uniformity TC4 titanium alloy large-size fine-grain blisk, which comprises the steps of completing cogging and forging of an alloy cast ingot at 1050-1150 ℃, 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 880-910 ℃, preserving heat for 12-20 h, then heating the blank to 940-980 ℃ along with a furnace for forging, then performing upsetting and drawing deformation on the blank at 935-985 ℃ for 6-8 fire, and then forming the blank at 945-965 ℃ to obtain a forged blank; and finally, annealing the obtained forging stock to finally obtain the blisk forging stock. The process is suitable for preparing blisk forgings with the height of 600mm to 1500mm and the height of 60mm to 150mm, and the structure uniformity and the performance of the forgings are superior to those of the traditional process.

Description

Preparation process of high-uniformity TC4 titanium alloy large-size fine-grain blisk

Technical Field

The invention belongs to the field of new material processing, and particularly relates to a preparation process of a high-uniformity TC4 titanium alloy large-size fine-grain blisk.

Background

TC4 is born in the fifties of the last century, is the most widely used titanium alloy at present, and can reach 400 ℃ in long-term use. In the field of aviation, TC4 is mainly used for manufacturing fans, compressor disks and blades of aircraft engines. With the increase of the thrust of the aero-engine, the size of the blisk gradually increases.

The TC4 blisk forged piece produced by the existing process is mostly within 1000mm in size, and the structure and the mechanical property of the forged piece can be guaranteed. However, if the size of the blisk is increased continuously, the uniformity of the structure of the blisk is difficult to guarantee, and the phenomenon that the mechanical property is difficult to reach the standard occurs. Therefore, how to realize the forming of the large-size blisk through process optimization becomes a focus of attention of related practitioners.

Disclosure of Invention

The invention aims to provide a preparation process of a high-uniformity TC4 titanium alloy large-size fine-grain blisk. 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 remarkably improved compared with the traditional process. The method has the advantages of simple operation, short flow, high stability and suitability for industrial production.

The invention provides a preparation process of a high-uniformity TC4 alloy large-size fine-grain blisk, which comprises the following specific steps:

step 1) firstly heating the alloy ingot to 1150-1250 ℃, preserving heat for 15-35 h, discharging from the furnace and forging to finish 1 upsetting and drawing deformation, wherein the upsetting deformation is required to be not less than 50%, and the speed is 0.2s ^-1 ～0.08s ^-1 Forging, and then air-cooling 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 deformation is required to be not less than 50%, and the speed is 0.2s ^-1 ～0.08s ^-1 Water cooling after forging;

step 3) heating the blank to 880-910 ℃, preserving heat for 12-20 h, heating to 940-980 ℃ along with the furnace, and performing upsetting and drawing deformation for 1 heating time, wherein the upsetting deformation amount is required to be 30-45%, and the speed is required to be 0.05s ^-1 ～0.04s ^-1 To (c) to (d);

step 4) heating the blank to 935 ℃ -985 ℃ to carry out upset-draw deformation for 6-8 times of heating, wherein the upset deformation amount of each heating is required to be 30% -45%, and the speed is 0.05s ^-1 ～0.04s ^-1 Meanwhile, the accumulated forging ratio is more than or equal to 3.3, and the final forging temperature is not lower than 910 ℃;

step 5) forming the blank at 945-965 ℃, wherein the pressing amount of the forging blank per fire time is required to be 30-40%, and the speed is 0.005s ^-1 ～0.05s ^-1 Obtaining a forging stock;

step 6) annealing the forged blank obtained in the step 5), wherein the annealing system is as follows: keeping the temperature between 700 ℃ and 800 ℃ for 1h to 3h, and carrying out air cooling or air cooling after discharging.

The forming mode adopted in the step 4) of the preparation process of the high-uniformity TC4 titanium alloy large-size fine-grained structure blisk 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 the blank heating temperatureThe temperature is 0-60 ℃ below zero, 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 600 mm-1500 mm, the height of the blisk forge piece is 60 mm-150 mm, all parts of the forge piece are uniform in structure, and the performance is stable;

2) The tensile strength at room temperature of any part of the forge piece is not lower than 950Mpa, the yield is not lower than 850Mpa, the elongation is not lower than 15.0 percent, and the area shrinkage is not lower than 25 percent. The tensile strength of the tensile property at 400 ℃ is not lower than 650MPa; the elongation is not less than 20 percent, and the surface shrinkage is not less than 40 percent; the elongation of the sample is not less than 10.0% and the surface shrinkage is not less than 20% after the sample is exposed by heat at 400 ℃/100 h.

The invention aims to overcome the defects of the prior art, realize the control of the structure and the mechanical property of a forged piece while increasing the size of the blisk forged piece, and improve the service life and the reliability of the blisk.

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 a die forging of embodiments 3 and 4;

FIG. 6 is a high power texture picture of the rim of the die forging 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 magnification organization picture of a 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 ingot selected in the embodiment has the diameter of 600mm and the length of 1300mm, and comprises the following chemical components: al:6.52%, V:4.19 percent, and the balance of Ti and other inevitable impurity elements with the beta transition temperature of 1002 ℃.

Step 1) firstly heating the cast ingot to 1150 ℃, preserving heat for 15h, discharging from the furnace and forging to finish 1 upsetting and drawing deformation, wherein the upsetting pressing deformation rate is 0.1s ^-1 The deformation is 53 percent, and air cooling is carried out after forging to obtain a blank;

step 2) upsetting and drawing the blank obtained in the step 1) for 1 heating time at 1025 ℃ for deformation, wherein the upsetting pressing amount is 51 percent, and the deformation rate is 0.1s ^-1 The forging ratio is 3.8, and water cooling is carried out after forging;

step 3) heating the blank to 890 ℃, preserving heat for 15h, then heating the blank to 960 ℃ along with the furnace, carrying out upsetting and drawing deformation for 1 fire time, wherein the coarse pressing amount is 40 percent, and the deformation rate is 0.05s ^-1 Air cooling after forging;

step 4) heating the blank to 965 ℃, carrying out 6-time upsetting-drawing deformation, wherein the thickness reduction of each time of heating is 36-40%, and the deformation rate is 0.04s ^-1 The accumulated forging ratio is between 3.4 and 3.8, and the finish forging temperature is 910 ℃;

step 5) according to the design size of the final forging piece, blanking by a sawing machine, forming the blank at 955 ℃, wherein the forming pressing deformation is 40%, and the deformation rate is 0.04s ^-1 Obtaining a forging stock;

step 6) annealing treatment of the final forging stock, wherein the annealing system is as follows: keeping the temperature at 700 ℃ for 3h, and cooling in air after discharging; and finally, polishing the surface to obtain the forging with the diameter of 1200mm 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 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 1200mm 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 microstructure of the forging of example 1 was a duplex microstructure with a nascent alpha content of about 30%. The original beta crystal grain sizes of all parts of the forged piece are uniform, the sizes and the distribution of primary alpha phases are basically consistent, and no obvious structural difference exists at different positions (figure 1 and figure 2). The tensile strength of the forged piece at room temperature is more than 980MPa, the tensile strength at 400 ℃ is more than 670MPa, and meanwhile, the forging has higher plasticity and higher consistency of mechanical properties of different parts. After the forge piece is subjected to heat exposure at 400 ℃/100h, the tensile strength and plasticity at room temperature are not obviously reduced. The high power structure of the forging of example 2 is a duplex structure with a primary alpha content of about 31%. The primary alpha forms and distribution of different positions of the forgings are obviously different, and the original beta crystal grains are not uniform in size; (FIG. 3, FIG. 4). Compared with the embodiment 1, the forging has lower tensile property, and the property difference of the forging at each position is relatively large due to uneven structure.

TABLE 1 tensile Properties of the forgings of example 1

Table 2 thermal stability in example 1

Table 3 tensile properties of forgings in example 2

Table 4 thermal stability of forgings in example 2

Example 3:

the ingot size selected in example 3 is 500mm in diameter and 1300mm in length, and the chemical components are as follows: al:6.59%, V:4.31 percent, and the balance of Ti and other inevitable impurity elements, namely the beta transformation temperature is 1007 ℃.

Step 1) firstly heating the cast ingot to 1170 ℃, preserving heat for 15h, discharging and forging to finish 1 upsetting and drawing deformation, wherein the upsetting pressing deformation rate is 0.1s ^-1 And the deformation is not less than 50%, and air cooling is carried out after forging to obtain the blank.

Step 2) upsetting and drawing deformation are carried out on the blank obtained in the step 1) for 1 heating time at 1030 ℃, the upsetting pressing amount is 55%, and the speed is 0.1s ^-1 The forging ratio was 3.6, and water cooling was performed after forging.

Step 3) heating the blank to 890 ℃, preserving the heat for 15h, then heating the blank to 960 ℃ along with the furnace, and carrying out upsetting for 1 heating time, wherein the upsetting deformation and the drawing deformation are 44 percent, and the upsetting deformation rate is 0.05s ^-1 And air cooling after forging.

Step 4) heating the blank to 970 ℃ to perform upsetting and drawing deformation for 7 times, wherein the upsetting deformation is 36-39%, the accumulated forging ratio of each time is 3.5-3.9, and the finish forging temperature is more than 915 ℃;

step 5) according to the design size of the forge piece, adopting a sawing machine for blanking, adopting a near isothermal molding process, heating the die to 890 ℃, heating the forging stock to 955 ℃, and setting the deformation rate to 0.01s ^-1 The deformation is 40%, and air cooling is carried out after forging to obtain a die forging cake blank;

step 6) annealing the forging stock, wherein the annealing system is as follows: keeping the temperature at 700 ℃ for 2 hours, and cooling in air after discharging. And finally, polishing the surface to obtain the die forging with the maximum diameter of 1500mm and the maximum height of 120 mm.

Example 4:

example 4 is a comparative example to example 3, and the ingot size, chemical composition, beta transus temperature, and beta transus temperature selected were identical to those of 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 1, so that the forging with the diameter of 1500mm and the height of 120mm is finally obtained.

FIG. 5 is a schematic cross-sectional view of forgings of embodiments 3 and 4. The forgings of example 3 and example 4 were compared for structural mechanical property analysis. In example 3, the microstructure of the forging is a two-state structure, the primary alpha content is about 35%, the distribution is uniform, and the sizes of the original beta crystal grains and the primary alpha phase at different positions of the forging are similar (fig. 6-8). The room-temperature tensile strength of the forge piece exceeds 980MPa, the 400 ℃ tensile strength exceeds 670MPa, the maximum difference of the strengths of different positions does not exceed 50MPa, and meanwhile, the forge piece has higher plasticity. After the forge piece is exposed by heat at 400 ℃/100h, the tensile strength and plasticity at room temperature are not obviously reduced. The high power structure of the forging piece in the embodiment 4 is also a two-state structure, the primary alpha phase at the local position of the forging piece is not uniformly distributed, and the size of the original beta crystal grain is not uniform (fig. 9-11). The forging tensile property is obviously lower than that of the forging tensile property in the embodiment 1, and the performance difference of different positions is larger.

TABLE 5 tensile Properties of the forgings in example 3

Table 6 thermal stability in example 3

TABLE 7 example 4 forging tensile Properties

TABLE 8 example 4 forgings durability

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 in the protection scope of the present invention.

Claims (3)

1. A preparation process of a high-uniformity TC4 titanium alloy large-size fine-grain blisk is characterized by comprising the following specific steps:

step 1) firstly heating the alloy ingot to 1150-1250 ℃, preserving heat for 15-35 h, discharging from the furnace and forging to finish 1 upsetting and drawing deformation, wherein the upsetting deformation is required to be not less than 50%, and the speed is 0.2s ^-1 ～0.08s ^-1 Forging, and then air-cooling 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 deformation is required to be not less than 50%, and the speed is 0.2s ^-1 ～0.08s ^-1 Water cooling after forging;

step 3) heating the blank to 880-910 ℃, preserving heat for 12-20 h, then heating to 940-980 ℃ along with the furnace, carrying out upsetting and drawing deformation for 1 fire, wherein the upsetting deformation is required to be 30-45%, and the speed is 0.05s ^-1 ～0.04s ^-1 To (c) to (d);

step 4) heating the blank to 935-985 ℃ to carry out upsetting deformation for 6-8 times, wherein the upsetting deformation amount of each time is required to be between 30-45%, and the speed is 0.05s ^-1 ～0.04s ^-1 Meanwhile, the accumulated forging ratio is more than or equal to 3.3, and the final forging temperature is not lower than 910 ℃;

step 5) forming the blank at 945-965 ℃, wherein the pressing amount of each fire time of the forging blank is required to be 30-40%, and the speed is 0.005s ^-1 ～0.05s ^-1 Obtaining a forging stock;

step 6) annealing the forged blank obtained in the step 5), wherein the annealing system is as follows: keeping the temperature between 700 ℃ and 800 ℃ for 1h to 3h, and carrying out air cooling or air cooling after discharging.

2. The process for preparing a large-size fine-grained blisk of high-homogeneity TC4 high-temperature titanium alloy according to claim 1, characterized in that: the blisk forged piece with the diameter of 600mm to 1500mm and the height of 60mm to 150mm is prepared by adopting the process.

3. The process for preparing a large-size fine-grained blisk of high-homogeneity TC4 high-temperature titanium alloy according to claim 1, characterized in that: the forming mode adopted in the step 4) 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 blank heating temperature, and the deformation rate is 0.005s ^-1 ～0.05s ^-1 。

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