A near-net-shape forming process for titanium-based composite blades

Abstract

A near-net-shape forming process for a titanium-based composite integral blade disk comprises the following steps: obtaining a Ti55 alloy ingot by smelting and preparing the ingot into a Ti55 alloy powder by atomization; thoroughly mixing the Ti55 alloy powder with TiB2 particles in a certain proportion and then loading the mixture into a graphite mold; preparing a TiB-Ti55 composite integral blade disk blank by hot pressing and sintering; hot isostatic pressing the TiB-Ti55 composite integral blade disk blank at a temperature of 10°C to 50°C below the β-transition point, maintaining the temperature and pressure for 2 to 8 hours under an argon atmosphere; and heating the TiB-Ti55 composite integral blade disk blank to 540°C to 560°C in an argon-free atmosphere, maintaining the temperature for 15 to 50 hours under a pressure of 5 to 15 MPa, and then air cooling. The present invention improves the fatigue resistance of the TiB-Ti55 composite integral blade disk.

Description

Technical Field

[0001] The invention belongs to the field of titanium-based composite material processing, and in particular relates to a near-net-shape forming process for a titanium-based composite material integral blade disk. Background Art

[0002] With the continuous increase in the flight speed of high-Mach aerospace vehicles and the thrust-to-weight ratio of military turbofan engines, the design of new-generation aircraft engine components has placed increasingly stringent requirements on weight reduction, and the service temperatures of components are getting higher and higher. The density of titanium-based composite materials (~4.6g / cm3) is comparable to that of traditional titanium alloys, and their strength can be increased by ~150MPa at the same operating temperature. Therefore, titanium-based composite materials are ideal lightweight structural materials for the heat-resistant components of the new generation of weapons and equipment. Mastering the preparation technology of high-temperature, high-strength titanium-based composite integral blades can improve the preparation level of turbofan engines and also provide a research and development foundation for the lightweight design requirements of high-Mach aerospace vehicles. Summary of the Invention

[0003] The purpose of the present invention is to provide a near-net-shape forming technology for titanium-based composite blisks with Ti55 alloy as the matrix and TiB as the reinforcement phase. This process can directly produce TiB-Ti55 composite blisks with excellent fatigue performance through hot pressing and sintering. The specific technical solution is as follows:

[0004] A near-net-shape forming process for a titanium-based composite blisk is described, wherein the specific steps are as follows:

[0005] Step 1: Obtain Ti55 alloy ingot by smelting and prepare it into Ti55 alloy powder by atomization method;

[0006] Step 2: Mix Ti55 alloy powder and TiB2 particles in proportion and then put them into graphite mold;

[0007] Step 3: Prepare a TiB-Ti55 composite integral blade blank by hot pressing and sintering at a temperature of 1200°C to 1500°C, a pressure of 100 MPa to 200 MPa, and a sintering time of 4 hours to 12 hours;

[0008] Step 4: Hot isostatic pressing the TiB-Ti55 composite blisk blank at a temperature of 10°C to 50°C below the β-transformation point at a pressure of 120 MPa to 180 MPa, and maintaining the temperature and pressure for 2 hours to 8 hours in an argon atmosphere.

[0009] Step 5: In an argon-free protective environment, heat to 540° C. to 560° C., keep the TiB-Ti55 composite integral blade blank at a pressure of 5 MPa to 15 MPa for 15 h to 50 h, and then air-cool.

[0010] The preferred embodiment of the near-net-shape forming process of the titanium-based composite integral blade disk is as follows: step 1: after the Ti55 alloy ingot is atomized, Ti55 alloy powder with an average particle size of 80 μm to 150 μm and TiB2 particles with an average particle size of 1 μm to 10 μm are selected and fully mixed in proportion and then loaded into a graphite mold.

[0011] The preferred embodiment of the near-net-net forming process of the titanium-based composite integral blade disk is that, in step 2, the TiB2 added to the TiB-Ti55 composite integral blade disk accounts for 1 wt.% to 5 wt.%.

[0012] The preferred embodiment of the near-net-shape forming process of the titanium-based composite integral blade disk is that the TiB-Ti55 composite integral blade disk is subjected to surface grinding and polishing after the above-mentioned processing to remove the oxide layer and retain the oxygen permeable layer.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0014] 1) The present invention uses a Ti55 alloy, a near-α-type high-temperature titanium alloy of the Ti-Al-Sn-Zr-Mo-Si-Nd series, independently designed based on the electron concentration law of the Institute of Metal Research, Chinese Academy of Sciences, and co-developed by Baoti Group and Beijing 621 Institute, as the matrix. This alloy has passed the test of various equipment and is close to maturity. It has been used in the fields of aviation and aerospace and is an optimal matrix alloy for titanium-based composite materials.

[0015] 2) The TiB-Ti55 composite integral blade disk in the present invention is subjected to pressure annealing treatment in an argon-free protective environment, forming a gradient oxygen permeation structure on the surface, so that the strength of the sample surface to the matrix slowly transitions, thereby improving the fatigue resistance of the TiB-Ti55 composite integral blade disk. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a microstructure photograph of the TiB-Ti55 composite integral blade disk in Example 1 of the present invention. DETAILED DESCRIPTION

[0017] Example 1:

[0018] according to Figure 1As shown, the raw material is 0-1 grade sponge titanium, and the alloy elements Sn, Mo, Si, Nb and Ta are added in the form of an intermediate alloy. The Al part is brought in by the intermediate alloy, and the insufficient part is added as pure Al; Zr is added in the form of sponge Zr; the above materials are mixed and pressed into electrodes using a press; the electrodes are welded together and smelted three times in a vacuum consumable furnace to prepare a Ti55 alloy ingot with a composition of Ti-5.2Al-3.5Sn-3.0Zr-1.1Mo-0.4Ta-0.4Nb-0.25Si.

[0019] Ti55 alloy powder was prepared by argon atomization, thoroughly mixed with 3 wt.% TiB2 particles, and then loaded into a graphite mold for hot pressing and sintering at a temperature of 1350°C, a pressure of 150 MPa, and a sintering time of 8 hours. Metallographic measurements showed a phase transition point of 1020°C.

[0020] The TiB-Ti55 composite blisk blank was hot isostatically pressed at 990°C and 160 MPa, then held in an argon atmosphere for 8 hours. The blank was then heated to 550°C in an argon-free atmosphere, held at 5-15 MPa for 15-50 hours, and then air-cooled. After this treatment, the surface was polished to remove the oxide layer while retaining the oxygen-permeable layer. The resulting TiB-Ti55 composite blisk had a diameter of 1000 mm and a height of 150 mm.

[0021] Table 1 Chordal tensile properties of TiB-Ti55 composite blade in Example 1

[0022]

[0023] Table 2 Chordal fatigue properties of TiB-Ti55 composite blades in Example 1

[0024]

[0025] As can be seen from the above examples, the TiB-Ti55 composite blisks produced by the present invention not only possess a uniform microstructure but also exhibit unique mechanical properties. They exhibit high room-temperature and high-temperature strength, exceeding 1200 MPa at room temperature and 700 MPa at 600°C. They also maintain high fatigue resistance, with a room-temperature fatigue limit exceeding 550 MPa and a high-temperature fatigue limit exceeding 400 MPa at 600°C.

Claims

1. A near-net-shape forming process for a titanium-based composite blisk, characterized in that: The specific steps are as follows: Step 1: Obtain Ti55 alloy ingot by smelting and prepare it into Ti55 alloy powder by atomization method; Step 2: Mix Ti55 alloy powder and TiB2 particles in proportion and then put them into graphite mold; Step 3: Prepare the TiB-Ti55 composite integral blade blank by hot pressing and sintering. The sintering temperature is 1200-1500℃, the pressure is 100-200 MPa, and the sintering time is 4 h-12 h. Step 4: Hot isostatic pressing (HIP) the TiB-Ti55 composite blisk blank at a temperature of 10°C to 50°C below the β-transition point at a pressure of 120 MPa to 180 MPa, and maintain the temperature and pressure for 2 to 8 hours in an argon atmosphere. Step 5: In an argon-free protective environment, heat to 540°C~560°C, keep the TiB-Ti55 composite integral blade blank at a pressure of 5~15MPa for 15h~50h, and then air-cool to form a gradient oxygen permeation structure on the surface.

2. The near-net-shape forming process of a titanium-based composite blisk according to claim 1, characterized in that: In step 1, after the Ti55 alloy ingot is atomized, Ti55 alloy powder with an average particle size of 80 μm to 150 μm and TiB2 particles with an average particle size of 1 μm to 10 μm are selected and fully mixed in proportion and then loaded into a graphite mold.

3. The near-net-shape forming process for a titanium-based composite blisk according to claim 1, characterized in that: In step 2, the proportion of TiB2 added to the titanium-based composite integral blade disk is 1wt.% to 5wt.%.

4. The near-net-shape forming process for a titanium-based composite blisk according to claim 1, characterized in that: After the above processing, the titanium-based composite integral blade disk is subjected to surface grinding and polishing to remove the oxide layer and retain the oxygen permeable layer.

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