Crack initiation behavior of a Ni-based SX superalloy under transient thermal stress

Based on three-dimensional transient thermo-mechanical coupling theory and rate-dependent crystal plasticity theory, a transient thermal shock constitutive model was developed to investigate the crack initiation behavior under transient thermal stress of a V-notched Ni-based single-crystal superalloy at 25 °C ↔ 760 °C/900 °C/1000 °C. The evolution and distribution of the resolved shear stress and damage were simulated. Three surface heat transfer stages were considered during the water-cooling process in the simulation. The crack initiation lives and locations in the simulation results both showed good agreement with those observed in the experiments. The growth directions of the two main cracks were approximately 45° with the dendrite orientation, and the {111}<110> slip family was mainly activated.