Influence of steel texture on brittle crack propagation characteristics

Influence of grain orientation anisotropy (texture) on brittle fracture propagation properties in steel was analyzed based on a fracture mechanics model, which assumes that a crack propagates along the cleavage plane with the highest tensile normal stress among the cleavage planes in a grain. The model predicted the higher degree of zigzag crack path with higher intensity of grain texture. The degree of zigzag crack path was also predicted to increase with increasing crack-tip plasticity. This was explained by the fact that plastic crack-tip stress distribution has less potency of driving the crack direction back to the original crack direction than linear elastic crack-tip stress distribution does. Above results agreed well with observations of Charpy impact fracture surfaces of textured and non-textured steel.