CN101372730A - A γ”-Strengthened High-Performance Cast Nickel-Based Superalloy - Google Patents

Abstract

A γ"-strengthened high-performance casting nickel-based superalloy, characterized in that: the weight percentage of the alloy composition is as follows: C: 0.007-0.07; B: 0.007-0.09; Ce: 0-0.10; Y: 0-0.10; Co: 10.0-15.0; Cr: 15.0-20.0; Mo: 1.0-4.0; Al: 0.2-3.0; Ti: 0.5-3.0; W: 0-3.0; Nb: 2.0-6.0; Ta: 0-6.0; Ni balance; Among them, the impurity content: S≤0.01, P≤0.01, Si≤0.2, Pb≤0.0005, Bi≤0.0001, Mn≤0.2, Fe≤0.5; the invention changes the alloy composition, not only has higher high-temperature mechanical properties, but also has Good tissue stability at 700°C for long-term use can meet the needs of aerospace and aero-engine casings with higher service temperature and performance requirements.

Description

A γ”-Strengthened High-Performance Cast Nickel-Based Superalloy

technical field

The invention relates to industrial technology-metal material science, and particularly provides a γ"-strengthened high-performance casting nickel-based superalloy.

Background technique

Inconel 718 alloy was successfully developed by H.L.Eiselstein of INCO Alloys International Huntington Branch (Huntington), and was published in 1959. It is a body-centered tetragonal Ni3Nb (γ") and face-centered cubic Ni3 ( Al, Ti, Nb) (γ') precipitation strengthened nickel-chromium-iron-based deformed superalloy. The alloy has high tensile strength, yield strength, durable strength and plasticity between -253 and 650 ° C, and has Good corrosion resistance, radiation resistance, thermal processing and welding performance.

In the context of the rapid development of superalloy overall precision casting technology, Inconel 718 alloy, originally developed as a deformed superalloy, has also been used in the aerospace industry in the form of casting alloy since 1965. The corresponding casting alloy grade is Inconel 718C. In recent years, with the development of large-scale hot isostatic pressing (HIP) equipment adapted to the production of large-scale castings, and the in-depth research on processes such as repair welding and post-casting heat treatment, the manufacturing process of large-scale Inconel 718C structural castings with more complex structures and thinner wall thickness is becoming more and more advanced. It is mature and has gradually replaced the welded assembly of forgings, and is widely used in the manufacturing fields of various aero-engine casings and turbo pump casings of aerospace engines.

my country began to imitate Inconel 718 alloy in 1968, and the domestic brand is GH4169. As an imitation model of the casting superalloy Inconel 718C, my country has developed the K4169 alloy, which has been initially applied to the overall casting of the diffuser case and bearing ring of the aero-engine.

Although Inconel 718 alloy has excellent performance, because its main strengthening phase γ”-Ni3Nb is a metastable phase, when the temperature exceeds about 650 °C, γ” grows rapidly and coarsens, and transforms into its stable phase δ, resulting in alloy strength and The durable life decreases rapidly, so the alloy is generally only allowed to be used for a long time at 650°C.

For this reason, the present invention aims at the problem that the alloy γ” phase has poor stability and is easily transformed into a δ phase to reduce the performance of the alloy, and develops a 700°C strength level that is equivalent to the 650°C strength of Inconel 718C (K4169) alloy, and after long-term aging at 700°C A new alloy that can still maintain a stable structure and performance.

Contents of the invention

The purpose of the present invention is to overcome the shortcoming of the rapid decline in alloy strength and durable life when the working temperature of the K4169 alloy exceeds about 650°C, and especially to provide a γ"-strengthened high-performance casting nickel-based superalloy.

The present invention provides a γ”-strengthened high-performance casting nickel-based superalloy, which is characterized in that: the weight percentage of the alloy composition is as follows: C: 0.007-0.07; B: 0.007-0.09; Ce: 0-0.10; Y: 0- 0.10; Co: 10.0-15.0; Cr: 15.0-20.0; Mo: 1.0-4.0; Al: 0.2-3.0; Ti: 0.5-3.0; W: 0-3.0; Ni balance; Impurity content: S≤0.01, P≤0.01, Si≤0.2, Pb≤0.0005, Bi≤0.0001, Mn≤0.2, Fe≤0.5.

The inventive alloy is a cast superalloy. By reducing the content of Nb element to reduce and inhibit the solidification segregation of alloy elements, the solidification temperature range of the inventive alloy is reduced. Figure 1 shows that the solidification interval of the No.1 alloy is 60°C, which is significantly smaller than the solidification interval of the Inconel 718 alloy of about 100°C, which is conducive to improving the performance of the alloy casting process.

The strength of the invented alloy from room temperature to 700°C exceeds that of Inconel 718C (K4169) and Rene 220 alloys, and the strength at 700°C is comparable to that of Inconel 718C (K4169) and Rene 220 alloys at room temperature. After aging, the tensile strength at room temperature and 700°C is further improved, and the durability performance is also maintained at the same level as before aging.

It can be seen from Figure 1 that the peak solidification temperature of No.1 alloy is 1290°C, the final solidification temperature is 1350°C, and the solidification range is 60°C.

Advantages of this invention: the alloy of the present invention has good structural stability at 700°C, has excellent tensile properties from room temperature to 700°C and durable performance at 700°C, and can meet higher service temperature and performance requirements for the integral precision casting casing of aero-engines demand.

Description of drawings

Fig. 1 is the DSC curve during the solidification process of the alloy of the present invention (Alloy No. 1), and the cooling rate is 5° C./min.

Detailed ways

Example 1

The alloy of the present invention (No.1 alloy), the alloy composition is shown in Table 1.

The smelting process adopted is: after the master alloy is melted and cleaned, it is refined at 1500°C for 10 minutes, cooled to 1400°C for pouring, and the shell temperature is 800°C. The heat treatment system adopted is: 1180°C, 4 hours, air cooling→775°C, 4 hours, furnace cooling to 700°C→700°C, 10 hours, air cooling.

Table 1 No.1 alloy composition, wt%

Cr co A1 Ti Nb Ta Mo C B Y Ni 18.0 12.0 0.5 1.0 4.0 3.0 3.0 0.015 0.020 0.05 Bal

Table 2 Mechanical properties of No.1 alloy and its comparison with that of K4169

The mechanical properties of No.1 alloy and its comparison with that of K4169 are shown in Table 2. It can be seen that the room temperature tensile yield strength and fracture strength of the invented No.1 alloy are not much improved compared with the K4169 alloy, but the tensile strength at 700°C and the durability life at 700°C/580MPa are significantly improved compared with the K4169 alloy.

Example 2

The No.2 alloy composition of the present invention is shown in Table 3, and the smelting and heat treatment process is the same as that of Example 1.

Table 3 No.2 alloy composition, wt%

Cr co A1 Ti Nb Ta Mo C B Y Ni 18.0 12.0 0.5 1.0 3.0 5.0 3.0 0.015 0.020 0.05 Bal

Table 4 shows the mechanical properties of No.2 alloy of the present invention and its comparison with that of K4169. It can be seen that the room temperature, 700°C tensile yield strength, fracture strength and 700°C/580MPa durability life of No.2 alloy are significantly improved compared with K4169 alloy.

Table 4 Mechanical properties of No.2 alloy and its comparison with that of K4169

Example 3

The composition of No.3 alloy of the present invention is shown in Table 5, and the smelting and heat treatment process is the same as that of Example 1.

Table 5 No.3 alloy composition, wt%

Cr co Al Ti Nb Ta Mo W C B Y Ni 18.0 12.0 0.5 1.0 3.0 5.0 3.0 2.0 0.015 0.020 0.05 Bal

Table 6 shows the mechanical properties of No.3 alloy of the present invention and its comparison with that of K4169. It can be seen that the room temperature, 700°C tensile yield strength, fracture strength and 700°C/580MPa durability life of No.3 alloy are significantly improved compared with K4169 alloy.

Table 6 No.3 alloy mechanical properties and its performance comparison with K4169

Embodiment 4:

The composition of No.4 alloy of the present invention is shown in Table 7, and the smelting and heat treatment process is the same as that of Example 1.

Table 7 No.4 alloy composition, wt%

Cr co al Ti Nb Ta Mo W C B Y Ni 18.0 12.0 0.5 1.0 3.0 5.0 2.0 2.0 0.015 0.020 0.05 Bal

Table 8 shows the mechanical properties of No.4 alloy of the present invention and its comparison with that of K4169. It can be seen that the room temperature, 700°C tensile yield strength, fracture strength and 700°C/580MPa durability life of the No.4 alloy are significantly improved compared with the K4169 alloy.

Table 8 Mechanical properties of No.4 alloy and its comparison with that of K4169

Embodiment 5:

After the No.1 alloy was smelted and heat-treated according to Example 1, it was subjected to long-term aging at 700°C for 1000h, and then the durability performance test at 700°C/620MPa was performed. The durability performance results before and after long-term aging are shown in Table 9. It can be seen that the durability of No.1 alloy after long-term aging at 700 ° C for 1000 hours is not lower than that before long-term aging, but has been improved.

Table 9 Comparison of durability performance of No.1 alloy before and after long-term aging at 700℃/620MPa

state T/h δ ₅ ,% conventional heat treatment 124 2.0 700℃ 1000 hours long-term aging 191 2.0

Embodiment 6:

The No.4 alloy of the present invention, its smelting and heat treatment process are the same as in Example 1, and its tensile properties at different temperatures and its performance comparison with K4169 alloy are shown in Table 10. It can be seen that the yield and fracture strengths of the No.4 alloy of the present invention are significantly higher than those of the K4169 alloy at various temperatures from 25 to 700°C.

Table 10 Comparison of tensile properties of No.4 alloy and K4169 alloy at different temperatures

Embodiment 7:

After the No.4 alloy was smelted and heat-treated as in Example 1, it was subjected to long-term aging at 700°C for 500 hours, and then a durability test at 700°C/620MPa. The results of the durability before and after long-term aging are shown in Table 11. It can be seen that the durability of the alloy after long-term aging at 700°C for 500 hours is not lower than that before long-term aging, but has been improved.

Table 11 Comparison of durability performance at 700℃/620MPa of No.4 alloy before and after long-term aging

state τ/h δ ₅ ,% conventional heat treatment 250 1.0 Long-term aging at 700°C for 500 hours 302 3.0

Claims (1)

1. A γ"-strengthened high-performance casting nickel-based superalloy, characterized in that: the weight percentage of the alloy composition is as follows: C: 0.007-0.07; B: 0.007-0.09; Ce: 0-0.10; Y: 0-0.10; Co: 10.0-15.0; Cr: 15.0-20.0; Mo: 1.0-4.0; Al: 0.2-3.0; Ti: 0.5-3.0; W: 0-3.0; Nb: 2.0-6.0; Ta: 0-6.0; Quantity; Impurity content: S≤0.01, P≤0.01, Si≤0.2, Pb≤0.0005, Bi≤0.0001, Mn≤0.2, Fe≤0.5.

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