Features of the single crystal structure of the turbine blades made of carbon-free and carbon-containing nickel superalloys

Abstract

A comparative study of structural features of the blade castings having a single-crystal structure and made of heat-resistant carbon-free and carbon-containing high-temperature nickel alloys upon directional crystallization with 001 crystallographic orientation is carried out. The results of the effect of directional crystallization modes on the formation of the structure and defects of castings of working blades made of carbon-containing and carbon-free high-temperature nickel alloys are presented. Changes in the degree of pickling of the near-surface layer of casting are presented as a function of pickling conditions. The microstructure of the near-surface zone of castings made of ZhS32 heat-resistant alloy is studied after different modes of their technological processing. It is shown that blade castings with a single-crystal structure made of heat-resistant carbon-free superalloys have a tendency to formation of the block structure and appearance of surface recrystallized grains. Recommendations on the use of methods of nondestructive X-ray control of blades made of carbon-frees alloys and precautions regarding birth of microporosity on the shelf and in the blade lock are specified.