Influence of rolling temperature on the structural evolution and residual stress generation of nanocrystalline Nickel during nano-rolling process

KV Reddy and S Pal, COMPUTATIONAL MATERIALS SCIENCE, 184, 109935 (2020).

DOI: 10.1016/j.commatsci.2020.109935

Although the rolling process is significant on developing the preferred crystallographic orientation in the metallic sheets, its implementation at the nanoscale is uncertain. However, it is believed that the nano- rolling process can be realized with progressive scientific and technological advancement in material processing. Presently, we have modeled the rolling process of nanocrystalline Ni specimen using molecular dynamics simulations and investigated the underlying deformation mechanism along with the orientation evolution. Moreover, we have also analyzed the effect of temperature on the residual stress generation and the grain rotations. This atomistic model takes both shear and compressive forces into consideration, which makes it efficient in representing the actual deformation process. It is found that the compressive stress accumulation majorly occurs at grain boundary whereas tensile stresses are accumulated at triple junctions. At elevated temperatures, the stresses during the deformation are diminished and gets dispersed due to the thermal vibrations caused by the high temperature deformation. Through this study, we have evidently shown the orientation change, grain refinement, and formation of sub- grain boundaries during the rolling process. In addition, we have also characterized the specimens with virtual diffraction analysis, which has shown the preferred orientations to be (002) and (111) after rolling through the first and second set of rollers respectively.

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