Developing a sparingly doped high-temperature nickel alloy for gas turbine blades

Аuthors

Khryashchev I. I.^*, Danilov D. V., Logunov A. V.

United Engine Corporation “Saturn”, 163, Lenin av., Rybinsk, Yaroslavl region, 152903, Russia

*e-mail: dixpy@mail.ru

Abstract

Development of mono-crystal high-temperature nickel alloys for gas turbine blades and vanes is one of the leading trends ensuring enhancement of parameters, efficiency and reliability of modern gas turbines.

Currently, one of the most widely used alloys for turbine blades manufacturing is the second-generation domestic ZhS32 alloy with Re content of about 4.5%. The goal of this work consists in the alloy creation with the equivalent level of heat resistance, but with no expensive elements, such as rhenium and ruthenium.

Besides, determination of the optimum heat treatment mode based on experimental works in production is a costly method.

Computing diffusive activity of doping elements may allow decrease development costs and optimize the regime for realizing the total potential of the alloy, embedded while it’s designing.

Analysis of nickel high-temperature alloys was performed while this work execution, and an optimal scheme of doping process to achieve maximum heat resistance was selected. With application of the computer aided method for high-temperature alloys optimization a new sparingly doped alloy for gas turbine blades, meant for operating at the temperatures up to 1050°C. The alloy is distinguished by high structural stability and economical use of doping elements. The new sparingly doped alloy relates to the first generation. With this, it complies with the third generation GS32 alloy by the level of heat resistance at 1000°C.

In the course of the works, development of nickel- based heat resistant alloys has been analyzed and an optimum alloying system has been selected to achieve the maximum heat resistance of the alloy. With the use of computerized optimization method of heat resistant alloys, a new lean alloy has been developed for gas turbine blades intended for operation at temperatures to 1050°C. The alloy exhibits high structural stability and efficient use of alloying elements. A new lean alloy is the first-generation alloy but its heat resistance at 1000°C corresponds to that of the third-generation alloy ZhS32.

A unique techniques for determining the diffusion coefficient of doping elements, and, based on the obtained data, for determining an optimal duration of the thermal treatment, were developed.

The microstructural studies of a new sparingly doped SLZhS32 alloy were conducted; a thermal treatment mode was tested with account for the diffusion processes kinetics; the samples were fabricated and strength tests were conducted.

The developed new sparingly doped alloy can be widely used for gas turbine blades manufacturing, ensuring the cost reduction without deterioration of the alloy operational properties.

Keywords:

single-crystal nickel-based high temperature alloy, sparing doping process, microstructure, dendrite segregation, diffusion model, heat treatment

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