Effect of secondary orientation on notch-tip plasticity in superalloy single crystals

Effects of secondary orientations on long fatigue crack growth in a single crystal superalloy

“…However, the power-law exponent of its da/dN-DK curve is higher and eventually the FCG rates of orientation 4 exceed those of orientations 5 and 6 in the intermediate to high DKs. 3. FCG rates in all the three in-plane directions of type-A slabs are much higher than those of type-B slabs at a given DK.…”

“…However, the secondary orientations, which are normal to the solidification direction, are neither specified nor controlled in the manufacturing process, and thus can vary from 0°to 90° [3]. Early investigations on single crystal blades assumed that it was unnecessary to control the secondary orientation [4], yet more recent studies have shown that the high cycle fatigue performance [2], the FCG response [5], and the notch-tip plastic behaviors [3,6] are appreciably affected by the secondary orientations of single crystal blades.…”

“…However, due to the material anisotropy, fatigue responses and failure modes of single crystal blades are too complicated to predict. Up to date, limited work has been done on the modeling of fatigue crack propagation in association with the secondary orientation effects [2,3,[5][6][7]. Ever since the pioneer work of Paris and Erdogan [8], the famous Paris equation has been successfully employed in characterizing FCG behaviors of most polycrystalline materials.…”

Molecular Dynamics Simulation of Crack Propagation in Nanoscale Polycrystal Nickel Based on Different Strain Rates

“…Kartal et al [10] studied the effect of crystallographic orientation on stress state and plasticity at the crack tip in a hexagonal close-packed (HCP) single crystal Ti through CPFEM and they found that the size and shape of the plastic zone at the crack tip is strongly dependent on crystallographic orientation, but the stress state at the crack tip shows little dependence on crystallographic orientation. Sabnis et al [11] studied the influence of secondary orientation on plastic deformation near the notch tip in a notched Ni-based single crystal by means of CPFEM, where the slip patterns and the size and shape of plastic zone are strongly dependent on the secondary orientation of the notch, which has an important effect on the initiation and propagation of crack. Li et al [12] predicted the initiation of a fatigue crack in a polycrystalline aluminum alloy by means of CPFEM, where the grain size, grain shape and grain orientation are considered.…”

Finite element simulations of notch tip fields in magnesium single crystals

“…In the context of FCC single crystals, several investigators have studied the mechanics of fracture using analytical, numerical and experimental techniques (see, for example, Rice 1987;Patil et al 2008aPatil et al , b, 2009Crone et al 2004;Sabnis et al 2012;Biswas et al 2013). Crystal plasticity framework was employed by Patil et al (2008a) and Biswas et al (2013) along with finite element analysis to accurately predict the loaddisplacement response and pattern of slip bands near a notch tip in aluminum single crystals.…”