Ductile to brittle transition of an A508 steel characterized by Charpy impact test Part II: modeling of the Charpy transition curve

摘要

A finite element simulation of the Charpy test is developed in order to model the ductile to brittle transition curve of a pressure vessel steel. The material (an A508 steel) and the experimental results are presented in a companion paper (Part I [Engng. Fract. Mech.]). The proposed simulation includes a detailed description of the material viscoplastic behavior over a wide temperature range. Ductile behavior is modeled using modified Rousselier model. The Beremin model is used to describe brittle fracture. The Charpy test is simulated using a full 3D mesh and accounting for adiabatic heating and contact between the specimen, the striker and the anvil. The developed model is well suited to represent ductile tearing. Using brittle failure parameters identified below -150 deg C, it is possible to represent the transition curve up to -80 deg C assuming that the Beremin stress parameter sigma_u is independent of temperature. Above this temperature, a temperature dependent Beremin stress parameter, sigma_u, must be used to correctly simulate the transition curve. Quasi-static and dynamic tests can then be consistently modeled.