Atomistic Simulation of Fatigue Crack Growth in α-Fe under High Temperature

Abstract

The crack growth behaviors loaded in mode I under strain and stress control at different temperatures were presented in α-Fe by atomistic simulations using LAMMPS code. The interatomic bonds of atoms were characterized using the embedded atom method interatomic potential. The simulation models were built with initial edge crack subjecting to cyclic uniaxial constant strain rate and constant stress. A temperature range from 100 K to 1200 K was considered to probe the influence of the temperature on crack growth. The crack growth mechanism and the radial distribution function (RDF) during crack growth were investigated. The results indicated that the crack propagation mechanisms were sensitive to temperature and the boundary conditions. By proposed image adjusting technology the dislocation slip bands can be more clearly displayed on screen. In order to include the effect of temperature on crack growth, a temperature factor defined as a function of temperature in exponential form was introduced to modify the theoretical expressions based on thermal activation theory. Its coefficient and index can be determined by the RDF peak value obtained from atomistic simulations. For cyclic loading the crack growth process was dependent on both temperature and cyclic loading period in terms of simulations.