This thesis is focused on processing of pure magnesium by high pressure torsion method (HPT). This process belongs to the group of intensive plastic deformation methods (SPD). SPD methods are in the centre of scientific interest for several decades. Theoretical part of this thesis puts an effort to summarize basic knowledge and principles of SPD methods with extra focus on method HPT. As theoretical part continues magnesium as technical material is presented. Influence of SPD on use and properties of pure magnesium is then presented. This trend is further developed in effort to describe the effect of individual HPT process variables on the properties of pure magnesium and its alloys. Focus of practical part of this thesis is in influence of number of revolutions. Samples were processed at 1/8, 1/4, 1/2, 1, 4 and 8 turns at room temperature. Speed of process was 1rpm and applied pressure was 6 GPa. The structure of commercially pure magnesium prepared by casting and moulding were observed with focus on differences caused by input material. The structure was observed by both light microscopy and back scattered electron diffraction (EBSD), focusing on structure development, grain size and grain orientation. Compared to other works on similar topic, the emphasis here is on observing the microhardness on the vertical edge of the sample. The hardness shows a steep increase right after 1/8 of a turn. With increasing number of turns gradual homogenization of microhardness is presented accompanied by slight decrease in microhardness. No trend in microhardness relative to the distance from anvil has occurred. Structure observed with EBSD shows a bimodal character with larger grains oriented in the same direction. The three-point bending test didn’t end up as expected, and the approach to evaluation of magnesium-based HPT needs to be re-evaluated for future work. A three-point bending test was designed for the initial assessment of the basic mechanical properties of the material.
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:400834 |
| Date | January 2019 |
| Creators | Poloprudský, Jakub |
| Contributors | Němec, Karel, Doležal, Pavel |
| Publisher | Vysoké učení technické v Brně. Fakulta strojního inženýrství |
| Source Sets | Czech ETDs |
| Language | Czech |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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