Recrystallization and fatigue fracture of single crystal turbine blades

Two rotor blades in an aero-engine fractured during testing. The fracture mode and cause were analyzed on the basis of fracture surface observation, chemical analysis, and metallurgical structure examination. The results show that the two blades failed in the same mode – fatigue fracture caused by recrystallization. In order to find out the cause of recrystallization, simulation tests were carried out by grit blasting and solution heat treatment. It is found that recrystallization formed during solution treatment because of the plastic deformation by grit blasting, and with the increase of the pressure and time for grit blasting, the depth of the recrystallized layer went up.