ABSTRACT
This chapter describes the low cycle fatigue (LCF) process using the ICFT model with cyclic deformation manifested as competition between plasticity (with or without dynamic strain aging) and creep mechanisms. For mechanical life, the Tanaka-Mura model is modified with the corrected dislocation dipole pileup strain formulation and thus the fatigue crack nucleation life is predicted just based on the material’s Burgers vector, Poisson’s ratio, elastic modulus and surface energy, without resorting to experiments, for the first time in the 150-year history of fatigue study. For high temperature LCF, the ICFT model evaluates the life evolution with consideration of internally distributed damage via creep and intergranular embrittlement, as well as oxidation. Thus, the ICFT model describes the many-faceted phenomena of LCF including the crossover-behavior, the temperature and frequency dependence of LCF life. Demonstrations are shown for ductile cast iron, austenitic cast steel, and Co/Ni base superalloys.
