Development of technology for directed crystallization of castings from heat-resistant and intermetallic alloys (review)

A review cocerning the improvement of the casting technology of turbine blades with a directional and single-crystal structure, casting equipment, as well as ways to improve the quality of the castings obtained is presented. It is shown that the technology of directional crystallization ensures the production of turbine blades made of new heat-resistant nickel alloys with high performance properties that meet the requirements for parts of modern gas turbine engines. The requirements for the structure of the turbine blades obtained from carbon-free alloys, as opposed to carbon-containing monocrystalline alloys, and for permissible deviations from the specified crystallographic orientation (CGO) of the blades are considered. The occurrence tendencies of characteristic defects of the single-crystal structure of the blades are investigated. The evolution of melting-and-casting equipment for directional crystallization, domestic and foreign, is presented, the conditions for the formation of a monocrystalline dispersed structure of heat-resistant alloys in thin sections of blades with a new penetrating cooling method are discussed.