Effect of pre-rafting on creep properties of Ni-based single crystal superalloy

Uniaxial tension creep tests were carried out along the [001] direction for as-heat treated Ni-based single crystal superalloy with cubic c' phase and pre-rafting samples with N-type rafted c' phase at 980 8C and 300 MPa. By comparing the differences in the creep curves between the as-received and pre-rafting samples, the influence of pre-rafting on creep properties was studied. It was demonstrated that the sample with the cubic c' phase exhibited a lower creep rate and a longer rupture life compared to the rafted c' phase. This paper discusses the evolution of the microstructure, especially the matrix channel width. The influence of rafting on creep deformation was incorporated into the modified crystal plasticity model via the dependence of the Orowan stress on the matrix channel width. Finite element calculation was performed to predict the creep behavior, which agreed well with the experimental data.