Microstructural and Mechanical Property Changes in Gas Turbine Blades Due to Elevated Operating Temperatures

The increase in operating temperature of gas turbines is driven by various factors, including the pursuit of higher efficiency, the necessity to operate turbines at maximum capacity, and unavoidable deviations from normal conditions due to operational challenges. Consequently, the discussion of microstructural changes resulting from temperature elevation has always been pertinent. For turbine blades manufactured from superalloys, defined operational hours are established, and after surpassing these hours, rejuvenation or complete replacement becomes necessary. However, a review of reference books and gas turbine manuals reveals a lack of precise definitions for deviations from normal temperature conditions. Another ambiguity in this context is the nature of microstructural changes that occur when exposed to high-temperature ranges, the extent of these changes concerning turbine operational hours, and ultimately, how these potential microstructural changes impact the mechanical properties of the alloy at high temperatures. Determining the type of structural changes, their consequences, and specifically the degree of mechanical property degradation assists in optimizing the timing for blade replacement or rejuvenation operations. Several blades from the first and second stages of the compressor turbine, as well as blades from the Ruston power turbine section, were examined in this study. This report aims to evaluate the effectiveness of this process and the extent to which the microstructural and mechanical properties of the blades are restored to their original conditions.

کلیدواژه ها:

Gas Turbines ، Superalloys ، Rejuvenation ، Microstructure ، Mechanical Properties