Microstructure Investigation of Gas Turbine Blade Nickel Based Superalloy IN738LC After Remelting

Microstructure of well worn gas turbine blade made of IN738LC Nickel-based superalloy was investigated.The microstructural characterization involved use of both optical as well as electron microscopes including application of EDS technique for studying carbide analysis. The blade was remelted under neutral atmosphere as a part of charge for casting new blade and the microstructure and hardness was investigated. In the yield sample the ordered cubical γ' precipitate was observed. Precipitation films of carbides at the interdendritic regions were caused in increasing hardness and thus the creep ductility was decreased.