Investigating the mixed-mode creep crack growth behavior of GH4169 superalloy: Experimental and numerical approaches

Time-dependent fracture mechanics primarily addresses creep crack growth (CCG) in creep-ductile materials. However, certain superalloys exhibit creep-brittle behavior, where CCG rates are governed by K. In this study, the mode I and I/II mixed mode CCG behavior of the superalloy GH4169 at 550 °C were investigated using experimental and numerical methods. Scanning electron microscope observations showed that intergranular fracture dominated the initial and stable crack growth stages. Finite element analysis indicated that the crack tip remained small scale creep and predominantly exhibited mode I behavior once crack growth initiated. For various loading angles, the da/dt-K_I curves aligned along a single line. The crack growth angle, predicted by MTS theory, showed good agreement with experimental results. Additionally, FRANC3D software was used to simulate the CCG behavior.