On the Observation of Internal Cracks and Microstructure of a Post Service Turbine Blade from a Civil Aeroengine

Abstract

  A post service examination of a turbine blade from a civil aeroengine has been carried out to ascertain the degree of microstructural coarsening and the distribution of crack damage induced during service. This was with the purpose to elucidate their correlation with the actual operating conditions. Samples were sectioned from different parts of the turbine blade for detailed examination by optical microscope and scanning electron microscope. The average length of cracks was used as one of the parameters to quantitatively illustrate the distribution of cracks on the turbine blade. Experimental results suggested that cracks were mainly concentrated on certain area of the pressure side. Leading edge of the suction side of the turbine blade consisted of mostly coarsened microstructure due to higher temperature exposure. In conclusions, there was no clear correlation between the crack damage distribution and the degree of microstructure evolution.