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Dislocation Dynamics simulations investigating deformation heterogeneity in Zirconium

Prita Pant (IIT Bombay)

Discrete Dislocation Plasticity

Tue 4:20 - 5:40

RI Hall 108

Plastic deformation of metals is almost always heterogeneous – more so in hexagonal metals such as zirconium. We show application of Dislocation Dynamics simulations to understand orientation dependent heterogeneous deformation in bulk polycrystalline Zr. Simulations under plane strain loading are compared with results from rolling experiments that showed significant differences in plastic deformation between basal and non-basal grains. It was found that even at significant macroscopic reduction in thickness, many near-basal oriented grains undergo almost no deformation. However deformation heterogeneity decreased when deformation temperature was increased to 200°C. Dislocation dynamics simulations were carried out using the ParaDis program developed by Lawrence Livermore National Labs. The program was modified to incorporate slip systems for hexagonal crystals, and temperature dependent critical resolved shear stress was used as a threshold below which no dislocation activity was permitted. We show that the simulations capture orientation sensitivity of plastic deformation, as well as the effect of temperature. We also show that at elevated temperature, stresses due to dislocation interactions contribute to motion of dislocations on prismatic plane though these dislocations experience no resolved stress due to applied load. Thus dislocation interactions play a significant role in plastic deformation of Zr, especially at elevated temperatures.