LAUSR

To determine the physical significance of the impact toughness parameters and accurately characterize the low temperature impact toughness of transmission tower material Q420B, the finite element model of Charpy impact test is established on the basis of experiment. The simulation and test results are verified, and the specimen fracture is analyzed by scanning electron microscope. The formation and growth mechanism of the crack are dynamically analyzed. On this basis, energy separation method is used to investigate the effect of low temperature on impact toughness. The results show that the simulation and test results are in good agreement, and the ductile-brittle transition temperature of Q420B is about −50°C. The breaking process of the specimen is divided into the crack formation and propagation. When temperature drops from 20 to −60°C, the crack propagation energy decreases from 51.0 to 11.9 J, the crack formation energy reduces from 39.9 to 15.8 J, and the fracture time of the material drops from 1.8 to 0.6ms.