Creep crack growth data reduction of directionally solidified Ni base superalloy using Ct estimation scheme for anisotropic materials

Abstract

Fracture parameters proposed to characterise crack-tip fields for isotropic materials need to be extended to evaluate the crack growth behaviour of anisotropic materials such as directionally solidified and single crystal superalloys. In this study, an estimation equation for the Ct-parameter is explained for transversely isotropic secondary creeping materials. In the previous study, a concept of equivalent creep coefficient Aeq was analytically derived and values of correction factors, β and , were also determined using finite element analysis. The proposed estimation equation for Ct is now applied to evaluate the creep crack growth of a directionally solidified Ni base superalloy. The results showed the validity of the proposed equation and provided a criterion to evaluate the creep crack growth for anisotropic creeping materials.