2014/04/25 by Hanno Gottschalk, Sebastian Schmitz, Gottschalk, H. +9 · 1 citation
Engineering · #47N30 #62G32 #FOS: Physical sciences #Fatigue and fracture mechanics #High Temperature Alloys and Creep #Materials Science (cond-mat.mtrl-sci) #Mechanical Failure Analysis and Simulation
paper · pdf · doi:10.48550/arxiv.1405.4743
openalex publication_date 2014/04/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We investigate the scatter in the cycles to crack initiation for conventionally cast specimens of the superalloy RENE 80 in total strain controlled low cycle fatigue (LCF) tests at 850°C. The grains at the location of crack initiation are investigated using electron backscatter diffraction (EBSD) measurements with scanning electron microscopy (SEM). This results in determination of maximal Schmid factors for the slip system that lead to the initiation of the LCF surface crack. It is shown using stress - life and strain - life models, that taking into account the Schmid factor considerable reduces the scatter in LCF life prediction. This is used to propose a probabilistic model for LCF life based on random grain orientations. Using Mote Carlo simulation, we determine the probability distribution for the maximal Schmid factor in an uniaxial stress state under isotropic random orientations of the grain. This is used to calculate failure probabilities under the above mentioned model and to compare them with experimental data. Based on extreme value statistics, it is discussed whether a high maximal Schmid factor can be considered as causally related to an early initiation of an LCF crack and we present some rather surprising experimental evidence. In the last section conclusions are formulated and future directions of research are outlined.