Papers by Keyword: Initial Grain Size

Abstract: A two-dimensional modified cellular automaton (CA) model was developed to simulate the dynamic recrystallization (DRX) behaviour during thermo-mechanical processing. It provides a link for multiscale modeling to bridge the mesoscopic dislocation activities with the macroscopic mechanical properties. This model is applied to investigate the effect of initial grain sizes on DRX process in commercial pure copper. The simulated results indicate that the stable size of recrystallized grain is independent on initial grain sizes. However, the percentage of DRX is not only related to the thermo-mechanical parameters, but also influenced by the initial microstructure. It is concluded that larger initial grain sizes promote a delay in the DRX occur on commercial pure copper. The calculated results compare well with the limited number of experimental observations and theoretical conclusions.

Abstract: The effect of initial grain size on the recrystallization behaviour of a type 304 austenitic stainless steel was investigated using hot torsion. Refinement of the initial grain size to 8 μm had a considerable effect on the flow curve shapes, peak and critical strains and also on DRX kinetics, compared with an initial grain size of 35 μm. Microstructural investigations using EBSD suggest a transition from conventional (discontinuous) to continuous dynamic recrystallization with decreasing initial grain size. Also, there was a moderate effect of initial grain size on the DRX grain size.

Abstract: High resolution Electron Backscatter Diffraction (EBSD) in a field emission gun scanning electron microscope (FEGSEM) was used to study substructural development during the deformation by cold rolling of a single-phase Al-0.1Mg alloy with initial grain sizes between ~3µm and 120µm. In the coarse-grained material, bands of elongated cells aligned at approximately 35º to the rolling direction were formed at low strains. However, as the grain size was reduced, fewer of these aligned microstructural features were formed, and at the smallest grain sizes, there was little evidence of significant substructure within the deformed grains. The alignment of low angle boundaries was analysed from EBSD data and shown to be a function of grain size, strain and boundary misorientation.