This master’s thesis is focused on optimalization of degassing parameters in the foundry plant and effect of these parameters on mechanical properties of Al-Si alloys. In practical part is used factorial experiment to research effect of degassing parameters on mechanical properties and dichte index. After optimalization the new process is validated by comparing with the previous one. This experiment was taken on AlSi7Mg0,6 alloy in foundry plant MESIT foundry, a.s.

The first chapter of the thesis deals with the occurrence of gases in the aluminum melt, what are their sources, what is the solubility of hydrogen in the aluminum melt and the formation of gas cavities. The second chapter divides the defects caused or associated with the presence of gases in the casting. They can be bubbles, shrinkage, or diluents. Pore morphology and its influence on mechanical properties are discussed. The third chapter deals with methods of melt degassing, either by vacuuming, bubbling with active or inert gases, or using special methods and preparations. In the fourth chapter methods for determination of hydrogen content in aluminum melt are divided into analytical methods, methods based on Sieverts law and indication methods. The fifth chapter deals with controlled gassing, its objectives and the preparations used for this purpose. The sixth chapter describes the experiment where the influence of the amount of Probat Fluss Micro 100 on the different casting thicknesses and its results were investigated using a test casting.

This master's thesis is focused on problem of welding of loading ramps and inspection of their welded joints. The aim of this thesis is to inspect the welds of loading ramps with regarding to the appearance of defects. The literature review of the research issues of the MIG welding technology and welding of aluminium and its alloys is described in this thesis. There is also described destructive and non-destructive inspection of welds that can be applied to inspection of loading ramps. Theoretical description is followed by an experimental part of the thesis. Experimental part is focused on the three destructive tests (the tensile, the macroscopic and the hardness test) of samples of loading ramps, which are made of EN AW-6005A T6.

This diploma thesis deals with cerium-based conversion coatings for aluminium alloys. At first the mechanism of protection of metals by inhibitory substances is described in the theoretical section. The next chapter is devoted to application of lanthanide salts as cathodic corrosion inhibitors. Then the characterization of alloy AA 2024 follows. The main part is dedicated to the growth mechanism of the cerium-based mixed conversion coating on the alloy AA 2024. Finally, the factors affecting the character and the quality of obtained coatings are commented. In the experimental part an influence of the thermal activation together with the activation by a hydrogen peroxide was observed. The created film was characterized using SEM and EDS. The level of corrosion protection was evaluated by the polarization resistance measurement. erized using SEM and EDS. The level of corrosion protection was evaluated by the polarization resistance measurement.

The thesis is focused on the surface treatment used for the preparation of aluminium alloys for the adhesive bonding. The theoretical part can be divided into three chapters. The first of them deals with aluminium alloys, the second one speaks about the adhesive bonding. The surface treatment itself, especially the conversion coating issues, is discussed in the last chapter. The experimental part is focused on the optimalization of a two-step titanium and zirconium based conversion coating technology. In the first part, the aluminium alloy is analysed by the glow discharge optical emission spectroscopy. The second part of the experiment deals with the first step of the technology, acidic deoxidation. The objective was to examine the influence of the exposure time on the morphology of the alloy surface and the shear strength of adhesive joints. In the last part of the experiment, the conversion coatings are prepared and characterised by the scanning electron microscopy and energy dispersive spectroscopy.

This study deals with influence of filters on running of aluminum metal flow. The main objective was to describe hydraulic resistances of assorted filters and running of silting filters by inclusions. Theoretical part generally describes filtration process and also filtration from the point of view of aluminum alloys and the most important characteristics of each type of alumina inclusions. Experimental part deals with flow rate tests, influence of filters on gassiness of melt and metallographic analysis. It was find out, that filter GEPHAL made minimal hydraulic resistance, on the other hand ceramic foam filters type LD made the maximal hydraulic resistance. It is necessary to reduce filtration surface for study running of silting filters by inclusions. Metallographic analysis showed amorphous alumina film inclusions, spinell Al2O3.2MgO, sludge and carbide of silicon.

This master's thesis deals with design and machining of the flange hub rear wheel of the formula by using CAD/CAM technology and CNC workshop programming. The introductory part provides theoretical description and characteristic of turning and milling technology. Further work describes aluminium alloys with focus on material which was used as a blank for machined workpiece. The practical part deals with design of flange in CAD software Autodesk Inventor, design of turning strategies in system ShopTurn and design of milling strategies in software PowerMILL. The final part of this thesis specifies realization of manufacturing on CNC lathe and CNC machining center in company BOSCH DIESEL s.r.o. in Jihlava. Last chapter is focused on techno-economic aspects of manufacturing.

New technologies of components assembling in car and aircraft industries and requests on improved mechanical and corrosion properties of metallic materials in the packing industry activate the utilization of highly innovative and unconventional manufacturing processes. There are only a limited number of processing, that retain the original material thickness and in an appropriate manner modify material properties. These are different types of annealing, severe plastic deformation methods or combination of both. In recent years constrained groove pressing (CGP) was devoloped with this method the grain size can be reduced from tens of micrometers to sub-micrometers. The present work is focused on a study of evolution of microstructure and mechanical properties of two alloys based on EN AW 3003 after CGP deformation and subsequent annealing.

The increasing global demand for a substantial lightweighting of automobiles to enable a reduction in the greenhouse gas (GHG) emissions and fuel consumption has led to the adaptation of the high strength Al wrought alloys such as the 2xxx and 7xxx series in near net-shaped manufacturing using the high pressure die casting (HPDC) process. However, the obstacle for this adaptation is the high susceptibility to hot tearing during the solidification of these alloys. A new structural Al alloy for high pressure die casting application was developed from the single-phase Al-Zn-Mg family; a high strength and ductile alloy that could be adapted to manufacturing automotive structural components using HPDC and help with a significant reduction in the overall curb-weight of an automobile and thereby increasing the vehicle fuel efficiency. The objective of this study was to enable a better understanding of the hot tearing phenomenon during solidification of the Al-3.8 wt%Zn-1 wt%Mg alloy, the effect of adding 1.2 wt% Fe to the alloy to improve the castability in HPDC process and the effect of adding Ti as a grain refiner of the primary Al phase during solidification of the alloy using Al-5 wt%Ti-1 wt%B master alloy. The constrained rod solidification (CRS) experiments were carried out to measure transient stress, transient strain, and transient temperature during solidification of the alloy. Improvements to the CRS experiments were also developed to obtain a repeatability of the acquired data. The computerized Tomography (CT) imaging was used to visually characterize the hot tearing. Hypothesis on the factors promoting the hot tearing tendencies in single-phase alloys solidified using net-shaped casting processes has been presented with evidence-based on transient stress-strain and thermal data curves obtained during the solidification experiments. / Thesis / Master of Applied Science (MASc)

M. Tech. (Department of Mechanical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / Though aluminium (Al) is justifiably described as a green metal with an increasing rate of application in structures, designers still restrain themselves from its applications as a load-bearing skeleton in structure due to insufficient design guidelines. This insufficient information is more with channel sections that might experience lateral-torsional buckling (LTB) when used as a load-bearing skeleton in structures. This study investigates the effects on imperfections on LTB load-carrying stability for 6061-T6 Al alloy channel section arches and proposed design guidelines. The case study focused on freestanding circular fixed end arches subjected to a transverse point load at the shear centre. The software package Abaqus was used to study a total of 110 arch models from three separate channel sections with an additional 16 arch models for validation. Sixty-six channel arches were developed at a constant length, while the remaining 44 arches were formed at constant slender ratios using 11 discrete included angles. The FE analyses methods used for the investigation were validated with existing analytical methods and showed good agreement, despite the assumptions of the bilinear curve used for material nonlinearity, initial geometric imperfections and residual stresses that presented the imperfections of the models. The different investigated factors include slender ratios, change in cross-section area, imperfections, and angles. These factors were found to have substantial impacts on the prebuckling state, which turns to impact LTB behaviour and load-carrying capacity. From arches developed at constant span length, the arches with moderately included angles (50°≤2𝛼≤90°) were found suitable for the designs against LTB, followed by the shallow (2𝛼<50°) and deep arches (90°<2𝛼≤180°) respectively. For arches developed at constant slender ratios, the deep arches were found to be more suitable in the design against LTB, followed by the moderate and shallow arches, respectively. In addition, it was realised that the change in web-flange thickness, section depth and slender ratios, had significant effects on the LTB loads magnitudes and very insignificant effects on the general behaviour across the included angles. The same occurrence was also observed on the prebuckling analyses. All the investigated channel section arches showed the imperfections to have significant impacts on the LTB loads. Arches developed at constant span length showed the maximum elastic LTB loads to have overestimated the expected real LTB loads by approximately 48 percent. While the maximum elastic LTB loads of arches developed at 𝑆𝑟𝑥⁄= 60 and 90 showed that the real LTB loads were overestimated by about 39 and 14 percent, respectively. That said, the elastic LTB loads on average overestimated the real LTB loads by over 50 percent for the arches developed at the constant span length and by only 18 percent for arches developed at the constant slender ratios.