Improvement of Operating Properties of Heat-Resistant Alloys by the Structure Optimization

Abstract

Fasteners of aircraft gas turbine engines are made of heat-resistant steels and alloys and are operated in intensive conditions under the action of high temperatures. For ensuring reliability, the connecting elements of aircraft engines are made of heat-resistant alloy steels. But under the influence of an aggressive environment, these elements are destroyed, resulting in problems during repairs. The structure of the material of fasteners during the threaded connection by cutting and plastic deformation is considered. The concentration of stresses in the thread plane depends on the density of dislocations, and the depth of corrosion penetration on the outer surfaces of the thread reaches 100 lm. It is proposed to introduce additional heat treatment of parts to improve the physical and mechanical characteristics of the alloy. After additional heat treatment, the r-phase plates dissolve and prevent the development of microcracks. It is proved that the density of material dislocations in the state of delivery reaches critical values, but the introduction of additional heat treatment allows to increase the performance of parts made of alloy HX -Alloy Type 66Ni-17Cr regardless of the method of threading. Prerequisites for the rational selection of heat treatment modes have been developed, which provide the best mechanical and technological characteristics and the necessary structure of the materials used.