Abstract
In this paper, the trans-grain extension behavior of crack tips is investigated. The crack propagation mechanism of BCC-Fe model of single and combination orientation under type I loading was studied by molecular dynamics method. It is found that crystal orientation has an important effect on the activation and evolution of crack growth. The propagation mechanism of each orientation in the combination model works together to control the propagation behavior of the crack. The results show that the combination of brittle cleavage and grains with weak ductility exhibits better ductility expansion. For the combination of strong ductility and weak ductility, the ductility behavior decreases, which will seriously harm engineering safety. The limiting effect of combination orientation can enhance the toughness of crack propagation. Stress concentration and shear bands are easy to form along the single layer twin, and the formation of slip bands in the weak toughness orientation reduces the crack propagation toughness behavior of the combined model.