CN115488277A - Preparation process of high-uniformity 650-DEG C high-temperature titanium alloy large-size fine-grain blisk - Google Patents

Abstract

The invention discloses a preparation process of a high-uniformity titanium alloy large-size fine-grain blisk with high temperature of 650 ℃, which comprises the steps of completing cogging and forging of an alloy cast ingot at 1150-1250 ℃, upsetting, drawing and deforming the obtained blank at 10-30 ℃ above a beta transformation point, cooling by water after forging, heating the blank to 850-870 ℃, preserving heat for 12-20 hours, heating to 990-1000 ℃ with a furnace, upsetting and drawing and deforming, heating the blank to 10-30 ℃ above the transformation point, upsetting, drawing and deforming, cooling by water after forging, heating the blank to 850-870 ℃, preserving heat for 12-20 hours, heating to 990-1000 ℃ with the furnace, upsetting, drawing and deforming the blank at 50-35 ℃ below the beta transformation point, and finally forming the blank at 50-40 ℃ below the beta transformation point to obtain a forged blank; and 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 600mm to 1000mm and the height of 60mm to 100mm, and the structure uniformity and the performance of the forge piece are superior to those of the traditional process.

Description

Fabrication of a high-uniformity 650°C high-temperature titanium alloy large-scale fine-grained blisk preparation process

technical field

The invention belongs to the field of new material processing, and in particular relates to a preparation process of a high-temperature titanium alloy large-size fine-grained integral blisk with high uniformity at 650°C.

Background technique

High-temperature titanium alloys are key materials for aero-engines. The amount of titanium alloy used in aero-engines is one of the important symbols of its advanced nature. The demand for aero-engines drives the development of high-temperature titanium alloys, and the development of titanium alloy material technology promotes the upgrading of engines. The maximum service temperature of existing mature high-temperature titanium alloys is 600°C. In order to meet the design requirements of a higher thrust-to-weight ratio, the number of stages of the next-generation engine compressor disk continues to decrease, the speed continues to increase, and the high-temperature section moves forward. The demand for medium and low-temperature titanium alloys has weakened, and there is an urgent demand for higher-temperature-resistant titanium alloys.

In order to reduce the structural weight of the compressor, it is urgent to use high-temperature, high-strength 650°C high-temperature titanium alloys instead of high-temperature alloys for the blisks of high-speed turbine engine compressors to reduce the weight of compressor components and improve engine efficiency and thrust-to-weight ratio. After the development of high-temperature titanium alloys to 600 °C, the required composition design and thermal processing technology are close to the limit of the current technological level. With the development of high-temperature titanium alloy from 550°C to 600°C, the thermal stability has more than doubled, and it is close to the design bottom line. Breaking through this bottom line will not guarantee the life of the parts and the safety and reliability of the design. Another issue is the control technology of material microstructure homogeneity exposed by the susceptibility to load fatigue. Using the same forging and heat treatment process to obtain a similar microstructure, the α+β-type titanium alloy has a low load fatigue sensitivity, while the near-α-type titanium alloy has a high load fatigue sensitivity, and a more uniform microstructure must be obtained to meet the More stringent performance control requirements. As the design temperature increases, the requirements for forging technology also increase accordingly. To this end, it is necessary to start from the basic research on composition design and thermal processing technology, and fundamentally solve the basic problems of composition optimization design and microstructure control that restrict the development of high-temperature titanium alloy technology above 600 °C, and then break through the development and application of high-temperature titanium alloys at 650 °C. It has an important material guarantee function and significance for the development of my country's future advanced engines.

Contents of the invention

The purpose of the present invention is to provide a preparation process of a high-temperature titanium alloy large-scale fine-grained integral blisk for 650°C with high uniformity. Compared with the traditional process, this process is suitable for the preparation of large-sized blisk forgings, and the microstructure uniformity and metallurgical quality stability of the forgings are significantly improved compared with the traditional process. The invention has the advantages of simple operation, short process and high stability, and is suitable for industrialized production.

The invention provides a preparation process of a high-temperature titanium alloy large-size fine-grained integral blisk with high uniformity at 650°C. The specific steps are as follows:

Step 1) First, heat the ingot of high-temperature titanium alloy at 650°C to 1150°C-1250°C, keep it warm for 10h-30h, and then take it out of the furnace for forging to complete one upsetting and pulling deformation; then return to the furnace for 1h-2h and then complete one upsetting , drawing deformation to obtain a blank, the deformation rate of each upsetting and pressing is 0.2s ^-1 ~ 0.08s ^-1 , the single upsetting deformation is not less than 50%, and air cooling after forging to obtain a blank;

Step 2) The billet obtained in step ¹ ) is subjected to ^upsetting and drawing deformation once at 20°C to 50°C above the β transformation point. Coarse deformation ≥ 50%, water cooling after forging;

Step 3) Heat the billet to 850°C-870°C and hold it for 12h-20h, then raise the temperature to 990°C-1000°C with the furnace to carry out the upsetting and drawing deformation once, and the pressing speed of upsetting is 0.05s ^-1 -0.04s ^{- 1} , the upsetting deformation is between 35% and 45%;

Step 4) repeat step 2) once;

Step 5) repeat step 3) once;

Step 6) Carry out upsetting and drawing deformation of the blank at 50°C-35°C below the β transformation point for 6-8 fires, and the upsetting rate for each fire is required to be between 0.05s ^-1 and 0.04s ^-1 , and press down The amount is between 30% and 50%, the cumulative forging ratio is ≥3.3, and the final forging temperature is not lower than 900°C;

Step 7) The billet is formed at 50°C to 40°C below T _β , and the deformation rate of the forged billet is required to be between 0.05s ^-1 and 0.04s ^-1 per firing, and the pressing amount is between 30% and 45%. get forged blank;

Step 8) Perform solid solution + aging heat treatment on the forged billet obtained in step 7), wherein the solution heat treatment system is: between 15°C and 25°C below T _β , heat preservation for 1h to 3h, water cooling or oil cooling after being released from the furnace; aging heat treatment For: keep warm at 680℃～720℃ for 4h～6h and then air cool.

The high-uniformity 650°C high-temperature titanium alloy large-size fine-grained monolithic blisk preparation process has a preferred solution: the composition mass percentage of the high-temperature titanium alloy ingot for 650°C is: Al: 5.0% to 6.3%, Sn: 3.0% to 5.0%, Zr: 2.5% to 4.0%, Mo: 0.2% to 0.7%, Si: 0.25% to 0.7%, Nb: 0.1% to 0.6%, Ta: 0.5% to 2.6%, W: 0.3% to 2.0%, C: 0.02% to 0.10%, and the balance is Ti and other unavoidable impurity elements.

The high-uniformity 650°C high-temperature titanium alloy large-size fine-grained integral blisk preparation process has a preferred solution: in step 3, in order to prevent cracking, the forging billet needs to be returned to the furnace for 2 hours after upsetting and then stretched .

The preferred method of the high-uniformity 650°C high-temperature titanium alloy large-size fine-grained overall blisk preparation process is that the forming method adopted in step 6) is an isothermal or near-isothermal forming process; an isothermal or near-isothermal forming process is adopted. During the die forging forming process, the mold needs to be heated to 0°C~60°C below the blank heating temperature, and the deformation rate is 0.005s ^-1 ~0.05s ^-1 .

Beneficial effects of the present invention:

1) The diameter of the blisk forging prepared by the present invention is 600mm to 1100mm, the height is 60mm to 130mm, the structure of each part of the forging is uniform, and the performance is stable;

2) The room temperature tensile tensile strength of any part of the forging in the present invention is not less than 1070Mpa, the yield strength is not less than 940Mpa, the elongation is not less than 10.0%, and the shrinkage is not less than 15%. After the sample is exposed to heat at 650°C for 100 hours, the elongation rate is not less than 3.0%, and the area shrinkage is not less than 6%. The tensile strength at 650°C is not less than 830Mpa, the yield is not less than 750Mpa, the elongation is not less than 20.0%, and the shrinkage is not less than 40%;

3) The present invention is based on the previous patented technology "A Novel Heat-Resisting Titanium Alloy and Its Processing and Manufacturing Method and Application" (publication number: CN104018027A), and solves the large-size integral blisk of a 650°C high-temperature titanium alloy through process optimization. Key technologies such as strength and toughness matching, structure uniformity, mechanical performance consistency and stability control of forgings, mastering the strength control, orientation uniformity control and high temperature long-term structure stability control methods of large-scale integral blisk forgings; the invention developed The 650°C high-temperature titanium alloy and blisk forging preparation technology can also be applied to other improved engines, replacing some high-temperature alloys, reducing the structural weight of the engine, and improving the fuel economy and thrust-to-weight ratio of the engine.

Description of drawings

Fig. 1 is the high-magnification microstructure picture near the surface of the forged billet prepared in Example 1;

Fig. 2 is the high-magnification microstructure photo of the center of the forged billet prepared in Example 1;

Fig. 3 is the high-magnification microstructure photo near the surface of the forged billet prepared in Example 2;

Fig. 4 is the high-magnification microstructure photo of the center of the forged billet prepared in Example 2;

Fig. 5 is embodiment 3 and embodiment 4 die forging schematic diagram;

Figure 6 is a high-magnification microstructure picture of the die forging wheel rim prepared in Example 3;

Figure 7 is a high-magnification microstructure picture of the die forging web plate prepared in Example 3;

Figure 8 is a high-magnification microstructure picture of the die forging hub prepared in Example 3;

Figure 9 is a high-magnification microstructure picture of the rim of the die forging prepared in Example 3;

Figure 10 is a high-magnification microstructure picture of the die forging web plate prepared in Example 3;

Fig. 11 is a high-magnification microstructure picture of the die forging hub prepared in Example 3.

detailed description

Example 1:

The ingot size of high temperature titanium alloy used for 650°C used in this example is 600mm in diameter, 1200mm in length, and the chemical composition is: 5.71Al-0.60Mo-3.26Zr-3.81Sn-0.92W-0.44Si-1.00Ta-0.41Nb-0.03 C, the β transition temperature is 1035°C.

Step 1) First, heat the ingot to 1150°C, keep it warm for 24 hours, and then take it out of the furnace for forging to complete one upsetting and drawing deformation; then return to the furnace for 2 hours to complete another upsetting and drawing deformation, and the compression deformation rate of each upsetting is 0.1 s ^-1 , the single upsetting deformation is 50%, air-cooled after forging, and the blank is obtained;

Step 2) Upsetting and drawing the billet obtained in step 1 at 1060° C. for 1 fire, the upsetting compression rate is 0.1s ⁻¹ , the deformation is 52%, the forging ratio is 3.8, and water cooling after forging;

Step 3) Heat the billet to 860°C for 15 hours, then upsetting with the furnace heating up to 990°C, then return the billet to the furnace for 2 hours, then continue to elongate, the pressing rate of upsetting is 0.05s ^-1 , and the deformation is 38 %, air cooling after forging;

Step 4) repeat step 2) process once to blank;

Step 5) repeat step 3) process once to blank;

Step 6) Heat the billet to 995°C for 7 times of upsetting and pulling deformation, the upsetting deformation rate of each fire is 0.04s ^-1 , the amount of pressing is between 37% and 40%, and the cumulative forging ratio is between 3.3 and 40%. Between 3.7;

Step 7) According to the design size of the final forging, use a sawing machine to cut the blank, form the blank at 970°C, the deformation rate is 0.04s ^-1 , the compression deformation under forming is 40%, and the forging blank is obtained;

Step 8) Finally, the forged billet is subjected to solid solution + aging heat treatment, wherein the solution heat treatment system is: 1023°C, heat preservation for 3 hours, and water cooling after being out of the furnace; the aging heat treatment is: 700°C heat preservation for 6 hours, then air cooling. Finally, the surface is polished to obtain a forging with a diameter of 800 mm and a height of 100 mm.

Example 2

This embodiment is a comparative example of embodiment 1, and the selected ingot size, chemical composition, and β transformation temperature are exactly the same as embodiment 1.

In this embodiment, in step 3 and step 5, the forging billet is directly heated to 990°C for upsetting and drawing deformation. The other steps are exactly the same as in embodiment 1, and finally a forging with a diameter of 800mm and a height of 100mm is obtained.

Analysis and comparison of the microstructure and mechanical properties of the forgings of Example 1 and Example 2: The high-magnification structure of the forging in Example 1 is a dual-state structure, the primary α content is about 12%, and the primary α and original β grains in each position of the forging are similar in size And the distribution is uniform and the consistency is good (Figure 1, Figure 2). The tensile properties of forgings at room temperature are not less than 1070MPa, and the tensile properties at 650°C are not less than 835MPa; after the forgings are exposed to 650°C/100h/heat exposure, the tensile strength at room temperature can reach 1080MPa, and the tensile strength at 120°C can reach more than 1060MPa. The difference in mechanical properties of different parts is relatively small. Example 2 The high-magnification structure of the forging is also a two-state structure, and the primary α content is about 14%. Different organizational characteristics (Figure 3, Figure 4). The tensile properties of the forgings are quite different at different positions. Compared with Example 1, the overall mechanical properties are relatively poor.

Tensile and KIC properties of forgings in Table 1 Example 1

Thermal stability in table 2 embodiment 1

Tensile and KIC properties of forgings in Table 3 Example 2

Forging thermal stability in table 4 embodiment 2

Example 3:

The size of the 650°C high-temperature titanium alloy ingot used in this example is 600mm in diameter, 1200mm in length, and the chemical composition is: 5.68Al-0.57Mo-3.31Zr-3.76Sn-0.89W-0.46Si-0.98Ta-0.45Nb-0.06C , The β transition temperature is 1038°C.

Step 1) First, heat the ingot to 1150°C, keep it warm for 24 hours, and then take it out of the furnace for forging to complete one upsetting and drawing deformation; then return to the furnace for 1.5 hours to complete another upsetting and drawing deformation, and the compression deformation rate of each upsetting, is 0.1s ^-1 , and the single upsetting deformation is 52%. Air cooling after forging to get the billet;

Step 2) The billet obtained in step 1) is subjected to upsetting and drawing deformation once at 1073°C, the pressing rate for upsetting is 0.1s ^-1 , the amount of deformation is 51%, the forging ratio is 3.6, and water cooling after forging;

Step 3) Heat the billet to 865°C for 15 hours, then heat up the furnace to 1000°C for ^upsetting , and then return the billet to the furnace for 2 hours and then stretch it. . Air cooling after forging;

Step 4) repeat the process of step 2) to the blank;

Step 5) repeat the process of step 3) to the blank;

Step 6) Heat the billet to 998°C, and then carry out upsetting and drawing deformation for 7 fires; the upsetting pressing rate for each firing is 0.04s ^-1 , the pressing amount is between 36% and 42%, and the cumulative forging ratio Between 3.3 and 3.6, the final forging temperature is 920°C, and air-cooled after forging;

Step 7) According to the design size of the forging, use a sawing machine to cut the material, adopt a nearly isothermal forming process, heat the mold to 953°C, heat the blank to 993°C, deform the rate of 0.01s ^-1 , and the deformation amount is 40%. After forging, it is air-cooled to obtain Die forging blanks;

Step 8) Perform solution + aging heat treatment on the forging blank, wherein the solution heat treatment system is: 1025°C, heat preservation for 2 hours, water cooling after being out of the furnace; aging heat treatment is: 700°C heat preservation for 8 hours, then air cooling, and finally the surface is polished to obtain a maximum diameter of 1000mm , height 80mm variable section forging blank.

Example 4:

The ingot size, chemical composition, and β transformation temperature selected by the present embodiment as the comparative example of embodiment 3 are exactly the same as embodiment 3.

In this embodiment, the process in step 3 and step 5 is changed to: the forging billet is directly heated to 1000° C. for upsetting and drawing deformation. Other steps are identical with embodiment 3. Finally, a variable-section forging blank with a maximum diameter of 1000mm and a height of 80mm is obtained.

The microstructure and mechanical properties of the forgings of Example 3 and Example 4 were analyzed and compared. Example 3 The high-magnification structure of the forging is a two-state structure, the primary α content is about 14%, the distribution of the primary α phase is uniform, the size of the primary α phase at different positions of the forging is similar, and the distribution is diffuse, the original β grains are uniform and fine, and the high-magnification structure of each position of the forging is There was no significant difference (Figure 6-8). The mechanical test results show that the tensile strength of the forging at room temperature is not less than 1070MPa, and the tensile strength at 650°C is not less than 830MPa. The forging has good plasticity; the forging also has good thermal stability. The sample was exposed to heat at 650°C/100h After room temperature to 120°C, the tensile strength did not decrease, and the overall forging showed relatively good structure and performance consistency. The high-magnification structure of the forging in Example 4 is also a double-state structure, and the primary α content is about 15%. The primary α content in different positions of the forging has obvious differences, and the original β grain size is not uniform. (Figure 9~11). There are also large differences in the mechanical properties of forgings at different positions. The web position has the highest strength and the lowest plasticity, while the hub and rim positions have lower strength and higher plasticity.

Tensile and KIC properties of forgings in table 5 embodiment 3

Forging thermal stability in table 6 embodiment 3

Tensile and KIC properties of forgings in Table 7 Example 4

Thermal stability of forgings in table 8 embodiment 4

The above-mentioned embodiments are only to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention shall fall within the protection scope of the present invention.

Claims (4)

1. A preparation process for a high-temperature titanium alloy large-scale fine-grained blisk with high uniformity at 650°C, characterized in that the specific steps are as follows: Step 1) First, heat the ingot of high-temperature titanium alloy at 650°C to 1150°C-1250°C, keep it warm for 10h-30h, and then take it out of the furnace for forging to complete one upsetting and pulling deformation; then return to the furnace for 1h-2h and then complete one upsetting , Pulling deformation, the deformation rate of each upsetting and pressing is 0.2s ^-1 ~ 0.08s ^-1 , the deformation of a single upsetting is not less than 50%, air cooling after forging, and the blank is obtained; Step 2) The billet obtained in step ¹ ) is subjected to ^upsetting and drawing deformation once at 20°C to 50°C above the β transformation point. Coarse deformation ≥ 50%, water cooling after forging; Step 3) Heat the billet to 850°C-870°C and hold it for 12h-20h, then raise the temperature to 990°C-1000°C with the furnace to carry out the upsetting and drawing deformation once, and the pressing speed of upsetting is 0.05s ^-1 -0.04s ^{- 1} , the upsetting deformation is between 35% and 45%; Step 4) repeat step 2) once; Step 5) repeat step 2) once; Step 6) Carry out upsetting and drawing deformation of the blank at 50°C-35°C below the β transformation point for 6-8 fires, and the upsetting rate for each fire is required to be between 0.05s ^-1 and 0.04s ^-1 , and press down The amount is between 30% and 50%, the cumulative forging ratio is ≥3.3, and the final forging temperature is not lower than 900°C; Step 7) The billet is formed at 50°C to 40°C below T _β , and the deformation rate of the forged billet is required to be between 0.05s ^-1 and 0.04s ^-1 per firing, and the pressing amount is between 30% and 45%. get forged blank; Step 8) Perform solid solution + aging heat treatment on the forged billet obtained in step 7), wherein the solution heat treatment system is: between 15°C and 25°C below T _β , heat preservation for 1h to 3h, water cooling or oil cooling after being released from the furnace; aging heat treatment For: keep warm at 680℃～720℃ for 4h～6h and then air cool. 2. According to the preparation process of a high-uniformity 650°C high-temperature titanium alloy large-scale fine-grained integral blisk described in claim 1, it is characterized in that: the composition content percentage of the 650°C high-temperature titanium alloy ingot is: Al: 5.0% to 6.3%, Sn: 3.0% to 5.0%, Zr: 2.5% to 4.0%, Mo: 0.2% to 0.7%, Si: 0.25% to 0.7%, Nb: 0.1% to 0.6%, Ta: 0.5% to 2.6%, W: 0.3% to 2.0%, C: 0.02% to 0.10%, and the rest is Ti and other unavoidable impurity elements. 3. According to the preparation process of a high-uniformity 650°C high-temperature titanium alloy large-scale fine-grained integral blisk described in claim 1, it is characterized in that: the forming method adopted in step 6) is an isothermal or near-isothermal forming process ; When the isothermal or near-isothermal die forging forming process is adopted, the mold is heated to 0°C-60°C below the heating temperature of the billet, and the deformation rate of the billet is 0.005s ^-1 -0.05s ^-1 . 4. According to the preparation process of a high-uniformity 650°C high-temperature titanium alloy large-scale fine-grained integral blisk described in claims 1-3, it is characterized in that: using this process can be prepared with a diameter of 600mm to 1000mm, a height of Integral blisk forgings between 60mm and 100mm.

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