To increase the reliability of single-crystal blade durability estimations a phenomenological model of single crystal superalloy plasticity based on the use of an “equivalent” direction and its software implementation has been developed. The relative orientation between principal stresses and single-crystal (SX) axes is considered by this direction. In order to study the effect of crystallographic orientation (CO) on the characteristics of a single-crystal material, a series of tests was carried out at various temperatures under tension under conditions of short-term and long-term loading. The possibility of using linear interpolation to determine the characteristics of plasticity and creep for intermediate CO has been confirmed. An example is given of using the developed calculation method in the Finite Element Analysis Software CalculiX using the model blade as an example.