Influence of Deviation and Randomness of Crystallographic Orientations on the Strength and Life of Nickel-Base Single Crystal Superalloy Turbine Blades

A two damage variable creep constitutive model has been presented for the strength and life of nickel base single crystal superalloy turbine blades.Uniaxial creep experiments for different orientations and stress levels have been conducted and validated for the model parameters.Modeling creep blades and double shear creep specimens were tested experimentally.The model has been validated by the uniaxial stress state and multiaxial stress state specimens.With the increase in deviation of the axial crystallographic orientations of the blade,the deviation of the strength increases,by the name of resolved shear stress of the slip systems.The randomness of the two uncontrolled crystallographic orientations of the blades results in a 15% deviation of the strength.The life deviation increases with the increasing deviation of axial crystallographic orientation.If there is a 15° deviation of the axial orientation,the life will have a deviation of factor 6.The randomness of the two uncontrolled orientations reduces 50% deviation of life.The study shows that the blade crystallographic orientations should be optimized for a better conjunction of strength and creep life.