Boundary Diffusion as the Controlling Mechanism of Ferrite Grain Size during Large Strain High Z Deformation in Low Carbon

摘要

During large strain deformation of materials, the high angle grain boundary spacing tends to approach the order of mean thermal diffusion distances for given deformation conditions. Since the evolution of ultrafine ferrite grains takes place by thermally activated processes, the role played by the interfaces such as grain boundaries in controlling the grain size is significant. In order to clarify the controlling mechanism of ferrite grain size formed during large strain deformation, a comparison of the characteristic diffusion distance with ferrite grain size formed may lead to an insight into the role of diffusion. For this purpose, both volume diffusion and grain boundary diffusion as the controlling mechanisms of ferrite grain size and its variation with Zener-Hollomon parameter 7 = Anti epsilon exp(Q/RT) are studied in detail here.