An Integration of 3D Discrete Dislocation Dynamics with Numerical Tensile Testing

Design of materials for severe high temperature mechanical exposures can be assisted by a newly developed 3D discrete dislocation dynamics model which can be tailored for a numerical simulation of hot tensile tests. The 3D discrete dislocation dynamics model is based upon the linear theory of elasticity. The dislocation structure is represented by short straight segments. This allows a straightforward calculation of the stress fields and, subsequently, the driving forces at any point in the simulation cell as a linear sum of stress contributions of individual dislocation segments, osmotic forces, externally applied stress, misfit stresses, the Peierls stress etc. Furthermore, the model addresses interaction between dislocation segments and rigid incoherent spherical precipitates. The dislocation displacement is calculated from the equations of motion, which address both dislocation glide and climb. The external loadings enter the model as an applied strain during a tensile test, from which the resolved shear stress is calculated. The resolved shear stress is calculated from the Hooke law and it is constant throughout the simulated volume during one integration step. Furthermore, a benchmark study is performed in which the 3D discrete dislocation dynamics model of the tensile test focuses on a migration of a low angle dislocation boundary in a field of rigid spherical precipitates. Obtained results are compared to former calculations during which the applied stress was kept constant.