Extrusion, as a metal forming process, represents a complete individual step in the entire metallurgical verification. In the case of heat-hardening alloys, heat treatment is also crucial in addition to deformation. Homogenization, which is carried out before the extrusion process, and aging, which is carried out after the extrusion process, are the key to the researcher in the industrial energy and economics. Optimizing more time and temperature favorable heat treatments presents challenges to research and scientific institutions, which helps in the progress of both metallurgical science and industrial plants. In addition to possible changes, the final products must provide suitable microstructure and mechanical properties.
The purpose of the master's thesis was to analyze the influence of heat treatments before and after the extrusion process on the final mechanical properties of extruded bars. The objectives were focused on the analysis of the precipitation hardening aluminum alloy EN AW-2011, the implementation of various heat treatments, tensile tests and measured hardness. At the same time, the results of mechanical tests were supported by the analysis with light microscopes, scanning electron microscopy and differential scanning calorimetry. The research problem was the search for optimal implementation of homogenization (before extrusion) and aging (after extrusion), where the implementation of such findings in industry would also represent an economic aspect.
The research work initially included a review and analysis of literature sources. At the forefront were the analyzes of heat treatments for related or similar alloys as EN AW-2011. Sampling of vertically semi-continuously cast bars was followed by systematic heat treatment (homogenization) at a temperature of 520 °C at 8 different times (laboratory annealing furnaces). Carrying out a DSC analysis, which was found to confirm the effectiveness and adequacy of the mentioned heat treatment. Based on these theses, the homogenization parameters were selected for further research.
The characterization of the extruded bars ensured the tracking of the entire, including the deformation part of the experimental process. Following the example of systematically performed heat treatment of homogenization, heat treatment of artificial aging was also performed. The range of mentioned heat treatments included three different temperatures and time intervals adapted to them. The scope of research in the production chain confirmed the most optimal parameters of homogenization at 520 °C for 4 hours and artificial aging at 170 ° C for 14 hours.
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