2. Alloy strengthening type
According to the type of alloy strengthening, superalloys can be divided into solid solution strengthening superalloys and aging precipitation strengthening alloys.
⑴Solid solution strengthening type
The so-called solid solution strengthening type means adding some alloying elements to iron, nickel or cobalt-based superalloys to form a single-phase austenite structure. The solute atoms deform the solid solution matrix lattice and increase the sliding resistance in the solid solution for strengthening. Some solute atoms can reduce the stacking fault energy of the alloy system and increase the tendency of dislocation decomposition, making it difficult for cross-slip to proceed, and the alloy is strengthened to achieve the purpose of strengthening the superalloy.
⑵Aging precipitation strengthening
The so-called aging precipitation strengthening refers to a heat treatment process in which the alloy workpiece is solid-solution treated and cold plastically deformed, and then placed at a higher temperature or maintained at room temperature. For example: GH4169 alloy has a maximum yield strength of 1 000 MPa at 650℃, and the alloy temperature for making blades can reach 950℃.
3. Material molding method
Divided by material forming methods: casting superalloys (including ordinary casting alloys, single crystal alloys, directional alloys, etc.), deformed superalloys, powder metallurgy superalloys (including ordinary powder metallurgy and oxide dispersion strengthened superalloys).
⑴Casting superalloy
The alloy material that directly prepares parts by casting method is called casting superalloy. According to the composition of the alloy matrix, it can be divided into iron-based casting superalloys, nickel-based casting superalloys and drill-based casting superalloys. According to the crystallization method, it can be divided into four types: polycrystalline casting superalloy, directional solidification casting superalloy, directional eutectic casting superalloy and single crystal casting superalloy.
⑵Wrought superalloy
It is still the most used material in aero-engines and is widely used at home and abroad. The annual output of deformed superalloys in my country is about 1/8 of that of the United States. Take GH4169 alloy as an example, it is one of the main varieties with the most applications at home and abroad. In China, the bolts, compressors, wheels, and oil slingers of turboshaft engines are mainly used as main parts. As other alloy products become more mature, the use of deformed superalloys may gradually decrease, but it will still be in the next few decades. Dominant.
⑶New superalloy
Including powder superalloys, titanium-aluminum intermetallic compounds, oxide dispersion-strengthened superalloys, corrosion-resistant superalloys, powder metallurgy and nano-materials and other subdivided product fields.
The degree of alloying of the third-generation powder superalloys has been increased, allowing it to take into account the advantages of the previous two generations, and obtain higher strength and lower damage. The powdered superalloy production process is becoming more mature, and the following aspects may be developed in the future : Powder preparation, heat treatment process, computer simulation technology, dual performance powder tray;
Titanium-aluminum intermetallic compounds have been developed to the fourth generation, and they are gradually expanding towards the two directions of multi-element micro-element and a large number of microelement. Hamburg University in Germany, Kyoto University in Japan, and GKSS Center in Germany have all conducted extensive research. Aluminum-based intermetallic compounds have now been used in the fields of ships, biomedical products, and sporting goods;
Oxide dispersion-strengthened superalloys are part of powdered superalloys. There are nearly 20 kinds of them under production. They have high high temperature strength and low stress coefficient. They are widely used in gas turbine heat-resistant and oxidation-resistant parts, advanced aero-engines, Petrochemical reactor, etc.;
Corrosion-resistant high-temperature alloys are mainly used to replace refractory materials and heat-resistant steels, and are used in construction and aerospace fields.