Due to the complex structure of gas turbine, the temperature and stress of each part are quite different, so the requirements and selection of materials are different.

1. Superalloy for combustion chamber

The mechanical stress of combustion chamber is small, but the thermal stress is large. The requirements for materials mainly include: high temperature oxidation resistance and gas corrosion resistance; Sufficient instantaneous and lasting strength; Good cold and hot fatigue performance, good process plasticity (durability, bending performance) and welding performance; The structure of the alloy is stable for a long time at working temperature.

2. Superalloy for guide vane

The first stage of the guide vane is one of the parts with the greatest thermal impact on the turbine engine. However, because it is stationary, the mechanical load is not large. The guide vane often fails in operation due to distortion caused by stress, cracks caused by drastic temperature changes and burns caused by over combustion. According to the working conditions of guide vane, the material is required to have the following properties: sufficient endurance strength and good thermal fatigue performance; High oxidation and corrosion resistance; If casting alloy is used, it is required to have good casting properties.

3. Superalloys for turbine blades

Turbine working blade is one of the most critical components in turbine engine. Although the working temperature is lower than that of the guide blade, the stress is large and complex, and the working conditions are bad. Therefore, the turbine blade materials are required to have high oxidation and corrosion resistance; High creep and rupture resistance; Good mechanical and thermal fatigue properties and good comprehensive properties at high and medium temperature.

4. Superalloy for turbine disk

The turbine disk is unevenly heated during operation, and the rim of the disk bears higher temperature than the center, resulting in great thermal stress. The tenon bears the largest centrifugal force, and the stress is more complex. Therefore, the material requirements of turbine disk are as follows: the alloy should have high yield strength and creep strength; Good cold, heat and mechanical fatigue properties; The linear expansion coefficient should be small, notch free sensitivity and high low cycle fatigue performance.

Development trend and new technology of Superalloys

In order to meet the needs of the new generation of gas turbines for high-performance materials, in addition to the continuous development of directional solidification casting technology and single crystal casting technology, Powder Superalloy technology and new high-temperature oxidation and gas erosion resistant protective coating technology have also been widely used. Powder Superalloy technology fgh51 Powder Superalloy is a phase precipitation strengthened nickel base superalloy prepared by powder metallurgy process. This alloy γ The volume fraction of the phase is about 25% - 50%, and the atomic fraction of the forming element is about 50%. The manufacturing process route of alloy disc is to prepare parent alloy by vacuum induction melting, and then atomize to prepare pre alloy powder, so as to make parts blank. Compared with similar cast and forged superalloys, it has the advantages of uniform structure, fine grain, high yield and good fatigue performance. It is a superalloy with the highest strength level at 650 ℃. This kind of high-temperature gold is mainly used for rotating parts of high-performance engine, such as turbine disk and bearing ring.