A method for preparing a Ti175 alloy blisk with basketweave structure

Abstract

A method for preparing a basket-structure Ti175 alloy blisk, step 1: heating the Ti175 alloy ingot to T β The temperature is 100℃~150℃ above the phase transformation point, and the temperature is kept for 10h~20h before forging. The forging ratio is not less than 4. Step 2: The blank obtained in step 1 is heated at T β The forging blank obtained in step 2 is heated to T β The die forging is performed at a temperature 10°C to 30°C above the phase transformation point. Step 4: The die forging blank prepared in Step 3 is heat treated and surface processed to obtain a Ti175 alloy blisk with a basketweave structure. In the present invention, the Ti175 alloy blisk undergoes triple heat treatment to form a gradient oxygen permeation layer on the blisk surface, significantly improving the fatigue performance of the blisk.

Description

Technical Field

[0001] The invention belongs to the field of titanium alloy processing, and particularly relates to a method for preparing a basketweave Ti175 alloy integral blade disk. Background Art

[0002] Titanium alloys have high specific strength, with a density of ~4.54 g / cm³, and exhibit excellent thermal stability and high-temperature strength. Maximizing the use of high-specific-strength titanium alloys is a key development direction for future advanced aerospace vehicles. The use of titanium alloys in domestic and international aircraft has increased significantly in recent years, and the amount and level of titanium alloy use have become important indicators of the advancement of domestic and international aerospace technology and aircraft performance. Ti175 alloy is a high-temperature titanium alloy capable of long-term operation at 550°C. This alloy offers significant advantages over other alloys, including significant performance advantages over TA15 alloy in various performance areas. Compared to TC4 and TC11 alloys, this alloy exhibits superior mechanical properties at high temperatures, with these advantages becoming increasingly pronounced with increasing temperature. Therefore, this alloy is expected to find widespread application in the aerospace industry, including in the manufacture of components such as high-Mach engine blisks. Currently, fatigue failure is the primary cause of component failure in this alloy. To achieve excellent fatigue performance, a dual-phase microstructure, achieved through two-phase deformation, is often employed. However, this inevitably limits the strength improvement of Ti175 alloy blisks. However, the basketweave structure produced by conventional β-forging often has poor fatigue performance and cannot meet the performance requirements of the aerospace field under complex service conditions. Summary of the Invention

[0003] The present invention aims to provide a method for preparing a Ti175 alloy blisk with a basketweave structure. The Ti175 alloy blisk prepared by this method can obtain a basketweave structure with high strength and high fatigue strength. The specific technical solution is as follows:

[0004] Step 1: Heat the alloy ingot to T β Above the phase transformation point, the temperature is 100℃~150℃, and the temperature is kept for 10h~20h before forging. The forging ratio is not less than 4;

[0005] Step 2: Place the blank obtained in step 1 on T β Above the phase transformation point, 20℃~50℃, perform 4~8 fires of upsetting deformation, and the forging ratio of each fire shall not be less than 3;

[0006] Step 3: Heat the forging blank obtained in step 2 to T β Die forging is performed at 10℃~30℃ above the phase transformation point;

[0007] Step 4: heat-treating and surface-processing the die forging blank prepared in step 3 to obtain a Ti175 alloy integral blade disk with a basket structure.

[0008] The preferred embodiment of the method for preparing a basketweave Ti175 alloy blisk is as follows: in step 2, the holding time is calculated according to the heating coefficient η = 0.2 min / mm to 0.5 min / mm.

[0009] The preferred embodiment of the method for preparing a basketweave Ti175 alloy blisk is as follows: in step 3, the die is first heated to 900° C. to 950° C., and after die forging, the forging blank is air-cooled to room temperature.

[0010] The method for preparing a basketweave Ti175 alloy blisk, the preferred embodiment of which is that the heat treatment process in step 4 is carried out at T β The first heat treatment is carried out at 10℃~50℃ above the phase change point, and after being heated through, it is kept warm for 1h~4h and then furnace cooled; the second heat treatment is carried out at 500℃~600℃, and after being heated through, it is kept warm for 6h~40h and then air cooled; the third heat treatment is carried out at 490℃~510℃, and after being heated through, it is kept warm for 50h~200h and then air cooled.

[0011] The preferred embodiment of the method for preparing a basketweave Ti175 alloy blisk is as follows: in step 4, the surface of the Ti175 alloy blisk is ground and polished after heat treatment. The advantages and benefits of the present invention over the prior art are as follows:

[0012] 1) The Ti175 alloy blisk produced by this process has a basketweave structure, which has higher room temperature and high temperature strength than traditional bimodal or equiaxed structures;

[0013] 2) After the Ti175 alloy integral blade disk in the present invention undergoes triple heat treatment, a gradient oxygen permeation layer is formed on the surface of the integral blade disk, which greatly improves the fatigue performance of the integral blade disk. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a 200x microstructure photograph of the Ti175 alloy blisk in Example 1 of the present invention;

[0015] Figure 2 This is a 2000x microstructure photograph of the Ti175 alloy integral blade disk in Example 1 of the present invention. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the embodiments.

[0017] Example 1:

[0018] like Figure 1-2As shown, the raw material used in this embodiment is a Ti175 alloy ingot with a diameter of 600 mm. The weight percentages of the alloy components are Al: 6.50%, Mo: 4.0%, Zr: 4.00%, Sn: 1.00%, W: 1%, Si: 0.5%, and the balance is Ti and other inevitable impurity elements. The β phase transformation temperature of the alloy detected by metallographic method is 980°C.

[0019] Step 1: Heat the TC11 alloy ingot to 1100°C, keep it warm for 16 hours, and then forge it. The upsetting deformation is 60%, and the total upsetting-drawing forging ratio is 4.5.

[0020] Step 2: The blank obtained in step 1 is subjected to two upsetting deformations at 1020°C with an upsetting deformation amount of 55%, two upsetting deformations at 1010°C with an upsetting deformation amount of 50%, and one upsetting deformation at 1000°C with an upsetting deformation amount of 40%.

[0021] Step 3: Heat the forging blank obtained in step 2 to 1000°C, heat the die to 950°C, and perform die forging.

[0022] Step 4: After die forging, the forging blank is heated at 1020°C for 2 hours and then furnace-cooled, then heated at 560°C for 8 hours and then air-cooled, and finally heated at 500°C for 75 hours and then air-cooled. After heat treatment, the Ti175 alloy blisk is polished to produce a 1000mm diameter basketweave Ti175 alloy blisk forging.

[0023] Table 1 Tensile properties of TiB reinforced Ti175 alloy in Example 1

[0024]

[0025] Table 2 Fatigue properties of TiB reinforced Ti175 alloy in Example 1

[0026]

[0027] It can be seen from the above examples that the basketweave Ti175 alloy blisk of the present invention not only overcomes the disadvantage of poor fatigue performance after conventional β forging, but also maintains relatively high room temperature and high temperature strength.

Claims

1. A method for preparing a Ti175 alloy blisk with basketweave structure, characterized in that: The specific steps are as follows: Step 1: Heat the Ti175 alloy ingot to T β Above the phase transformation point, the temperature is 100℃~150℃, and the temperature is kept for 10h~20h before forging. The forging ratio is not less than 4; Step 2: Place the blank obtained in step 1 on T β Above the phase transformation point, 20℃~50℃, perform 4~8 fires of upsetting deformation, and the forging ratio of each fire shall not be less than 3; Step 3: Heat the forging blank obtained in step 2 to T β Die forging is performed at 10℃~30℃ above the phase transformation point; Step 4: heat treating and surface processing the die forging blank prepared in step 3 to obtain a Ti175 alloy blisk with basketweave structure; The heat treatment process is β The first heat treatment is carried out at 10℃~50℃ above the phase change point. After being heated through, it is kept warm for 1h~4h and then cooled in the furnace. The second heat treatment is carried out at 500℃~600℃. After being heated through, it is kept warm for 6h~40h and then cooled in the air. The third heat treatment is carried out at 490℃~510℃. After being heated through, it is kept warm for 50h~200h and then cooled in the air. After triple heat treatment, a gradient oxygen permeation layer is formed on the surface of the Ti175 alloy blisk.

2. The method for preparing a basketweave Ti175 alloy blisk as claimed in claim 1, characterized in that: In step 2, the holding time is calculated according to the heating coefficient η = 0.2min / mm~0.5min / mm.

3. The method for preparing a basketweave Ti175 alloy blisk as claimed in claim 1, characterized in that: In step three, the die is first heated to 900°C to 950°C, and the forging blank is air-cooled to room temperature after die forging.

4. The method for preparing a basketweave Ti175 alloy blisk as claimed in claim 1, characterized in that: In step 4, the surface of the Ti175 alloy integral blade disk is ground and polished after heat treatment.

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