Influence of Strain Localization on Deformation Mechanisms and Fracture of 12CrlMoV Steel with Various Notch Shape under Impact Loading

摘要

The energy of 12CrlMoV steel specimen fracture with V-, U- and I-shaped notches under impact loading was measured and analyzed. The results were described using common energy-based approach to ductile-brittle fracture. Within the stage-wise approach of physical mesomechanics of materials, the rate of increase/decrease of load at the stage of initiation and propagation of a macroscopic defect was evaluated, providing a good correlation with the work of fracture. The excitable cellular automata technique was applied to simulate the deformational behavior of the specimens with different shape of notches. It was demonstrated that in the case of the blunted notch, the maximum impact toughness is facilitated by a more uniform distribution of the load along the notch, which hinders brittle fracture at lower testing temperature. For the specimen with the sharp I-notch, the bands of localized shear are oriented normally to the loading axis, inhibiting macrolocalization of strain and crack propagation. For this reason, the impact toughness of the specimen with the I-notch appeared to be higher than that of the V-notched one.