Molecular Dynamics Simulation of the Effect of Large Angle and Small Angle Grain Boundaries on the Near-Threshold Fatigue Crack Growth in Iron

Abstract

In the near-threshold region of the fatigue crack growth in metals, the amount of crack growth per cycle is in the order of the atomic scale. This may suggest that the near-threshold fatigue crack growth is controlled by atomic scale events. In previous papers the present authors applied the molecular dynamics to the simulation of near-threshold fatigue crack growth. In this study, the molecular dynamics method was applied to investigate the influence of inclined grain boundary on the near-threshold mode I fatigue crack growth behavior in BCC iron. Large angle grain boundaries served as an obstacle to the fatigue crack growth. Small angle grain boundaries had the effect of decreasing crack growth when the crack approached the grain boundary. When the crack reached the grain boundary it was trapped by the grain boundary.