Thermal Analysis and Microstructural Evaluation of Inconel 738LC Superalloy Gas Turbine Blade

The operational temperature of a gas turbine blade made of IN738LC superalloy was investigated. The component under evaluation was a first stage blade of a 25MW power plant gas turbine with the gas temperature of 943  in the first stage nozzle at the base load. The evaluation was carried out after 16000 h of operation in the mode of base load. To analyze the temperature distribution of the component, three 3D-models of the blade were prepared, meshed and analyzed using CFD software. The results indicate the higher temperatures in the upper section of the leading edge during steady state operation of the blade.To evaluate the reliability of this analysis, intermetallic  coarsening behavior was examined as the most important microstructural changes of the alloy after long term service exposure. This metallographic analysis also approves increasing in temperature with height of the airfoil section.