Failure analysis of J85 Engine turbine blades

This paper analyzes the cause of the engine damage due to the fracture of the J85 Engine first stage turbine blades. Discoloration due to thermal effect and fine multi-cracks as well as necking at 1/3 of the way down from the tip on the entire first stage turbine blade concave side surface have been noted. Of the first stage blades, nine had fractures 1/3 of the way down from the tip, and at the fractured location more severe necking has been found than blades without fracture. As a result of observing the fine texture of fractured blades and the blades where deformation has occurred, wedge-type intergranular cracks and TCP phase as well as carbide phase have been identified, and γ′ deformation and depletion found around the fracture surface. There were no traces of thermal damage to the first stage vane, no IOD phenomenon has been noted. Analysis of turbine blade deformation and fracture profile and microstructural deformation phenomenon determined that blade fracture was due to high temperature creep rupture.