Effects of crystallographic orientations and dwell types on low cycle fatigue and life modeling of a SC superalloy

Effects of temperature (760 °C and 980 °C), crystallographic orientation ([0 0 1], [0 1 1] and [1 1 1]) and dwell types (tensile, compressive and balanced dwell type) on low cycle fatigue (LCF) of a Ni-based single crystal (SC) superalloy are experimentally investigated and modeled. Since the LCF behavior shows strong crystallographic orientation and dwell type dependences, corresponding accurate life models are needed for safe application in gas turbine components. The feasibility of stress-based, strain-based and energy based models on anisotropic fatigue behavior was evaluated. A modified Cyclic damage accumulation (CDA) method combined with critical slip plane concept is developed to correlate the influence of orientation and dwell type on LCF data.

► Experimental investigations were carried out for anisotropic LCF behavior and CFI.
► Orientation dependence of LCF behavior of DD6 was investigated here.
► CFI were tested under three strain-hold types at different high temperatures.
► Orientation factor and critical plane based life models of LCF are evaluated.
► Based on CDA method, life models of CFI are combined with critical plane concept.