Vývoj procesu SPD z hlediska zvýšení efektivity metody ECAP

Abstract

The Dissertation thesis deals with efficiency increasing of Severe Plastic Deformation (SPD) of the technology Equal Channel Angular Pressing (ECAP) with the help of progressive geometry of segmental implement. In the introductory part of the Dissertation thesis is described in detail the problem and the theory of formation of Ultra Fine Grain (UFG) and Nanomaterials (NC). At the moment mainly extreme plastic deformation is used for the production of those materials. For the formation of those deformations are used several known so-called “top-down“ methods, which are based on the increasing density of dislocations during plastic deformation and the formation of fine grain to nanocrystalline structure. Among those methods belongs also Equal Channel Angular Pressing (ECAP). The development, current trends and results are summarized in the following chapters. In the next part of the Dissertation thesis is introduced experimental part, which deals with selected materials in the form of magnesium alloys, laboratory equipment and the construction of implements ECAP used for experimental verification. Those special segmental implements with helix inserted in horizontal trench were developed and their construction was verified subsequently on the Department of Mechanical Technology. In the final part of the Dissertation thesis are presented extensive results in the form of graphic and table evaluation of records of deformable resistance and strength needed for extrusion of single tested samples together with achieved hardness of the given materials. The efficiency of the new geometry of the implement ECAP is further verified by evaluation of microstructure due to optical microscope and transmission electron microscopy TEM. The conclusion of the work is dedicated to overall scientific contribution of achieved results based on obtaining new knowledge about the process of Equal Channel Angular Pressing (ECAP), its influence on selected magnesium alloys and possible application in industrial practice