Mechanical processing of ultrafine-grained materials produced by severe plastic deformation

Abstract

Microdrawing and micromachining are two advanced fabrication processes of a component in which at least two dimensions are below the millimetre. With such a reduced scale, the plastic and elastic anisotropies of coarse grained materials are very important, since they cause enhancement of crystallographic texture and deformation heterogeneity much larger than when the material has a small grains size. All techniques of Severe Plastic deformation are particularly suited to the above-mentioned manufacturing processes, because their leading effect is grain refining, from which a new class of materials known as "ultrafine grain size" is originated. What distinguishes a particular DPS process from the others is the kind of viscoelastic flow of the material and the deformation path. Thus, processes leading to a high level of shear and characterized by a non-conservative deformation path produce a quite random crystallographic distribution and lower anisotropy. This proposal has two main objectives:1) Extend the asymmetric rolling process to accumulative roll bonding for producing sheets of low crystallographic anisotropy;2) The study of the behavior of DPS processed materials, and its application to micro-deformation and micromachining processes. The project will be developed along the following lines:1) Study of the asymmetrical rolling process in terms of the deformation level and distribution, and the influence of the processing parameters on the total shear deformation of the sheet.2) Determination of the deformation and annealing textures of the sheets3) Application of the asymmetric rolling technique to the DPS process of accumulated rolling. This investigation is original and there are no mention of it in the literature.4) Initial studies for applying these processed materials to micromachining and microforming. (AU)