National Repository of Grey Literature 41 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Fatigue properties of materials prepared by SLM method
Hanáček, Josef ; Pantělejev, Libor (referee) ; Štěpánek, Roman (advisor)
This work deals with description of SLM (Selective Laser Melting) method, which is one of ALM (Additive Layer Manufacturing) method. In first part the general laws of fatigue and SLM method are described. The second part deals with the influence of processing parameters to final properties of material. The main goal of work is to determine dependence between processing parameters and mechanical properties of SLM processed components. Special attention is dedicated to fatigue properties.
Propeller fan damage analysis
Vašáková, Kristýna ; Štěpánek, Roman (referee) ; Pantělejev, Libor (advisor)
This bachelor’s thesis deals with propeller fan damage analysis, which is used for air blasting of recycled glass wool. In the frame of experimental work the fractographic analysis for evaluation of damage mechanisms was performed. Further, material analysis for assessment of the material grade (chemical and metallographic analyses) was conducted. Measurement of Vickers hardness with low load was performed for determination of mechanical properties of used materials.
Influence of thermal processing to microstructure of various steels
Kocman, Lukáš ; Havlík, Petr (referee) ; Štěpánek, Roman (advisor)
This bachelor thesis deals with the heat treatment of steel, especially measuring the influence of individual heat treatment technologies on changes in the microstructure of steels. The theoretical part of the work presents alloys of iron and carbon, furthermore describes their phase transformations in the solid state, particularly the transformation diagrams of steels. In another part of theoretical part, the basic heat treatment technologies and their influence on the mechanical properties and microstructure of steels are described. The experimental part deals with the preparation of metallographic samples and presents results of examining the microstructure and measuring the hardness of individual samples. At the end of the work the synthesis of the theoretical part and results of the experimental part is used for the partial and overall evaluation of the influence of heat treatment on the microstructure of steels.
Microstructural stability of materials prepared by aditive manufacturing methods
Hyspecký, Michal ; Pantělejev, Libor (referee) ; Štěpánek, Roman (advisor)
This work deals with the microstructural thermal stability of material 2618 produced by the Selective Laser Melting metho - SLM. Microstructural stability is compared with the stability of material produced by conventional methods. Stability itself is evaluated by changes of microstructure and microhardness. The main finding is that the sample produced by SLM method reached a microhardness of 125 HV 0.3 and after sixteen hours of annealing at 200 °C a decrease of only a few units to 120 HV 0.3 was recorded. Based on the data obtained, it was concluded that the sample produced by SLM method is structurally stable, as it did not occur any significant changes in the microstructure or in the observed mechanical properties. As a result, components produced by SLM method become usable in operation in places with an elevated temperature up to 200 °C (with a given choice of criteria).
Evaluation of mechanical characteristics of shape memory alloys under cyclic loading in torsion
German, Roman ; Štěpánek, Roman (referee) ; Horníková, Jana (advisor)
The main aim of this thesis is to process the results of fatigue tests of wires of a NiTi shape memory alloy subjected to symmetric cyclic torsion. The first part of this work is dedicated to literature research about NiTi alloys, their response to cyclic loading and the specific features of torsion loading. The second part contains a review of the influence of heat treatment and strain amplitude on the ability to dissipate mechanical energy, changes in mechanical properties and fatigue life of the tested material.
Duplex microstructures preparation by mechanical alloying and spark plasma sintering
Neboha, Oksana ; Štěpánek, Roman (referee) ; Moravčík, Igor (advisor)
This master´s thesis focuses on duplex microstructures preparation by powder metallurgy. A hybrid material can be created by combining two or more existing materials in different geometries, and thus the newly formed composite can provide a superposition of the properties of the starting materials (powders). This means that it will have an improved combination of the required properties. The theoretical part describes in detail the hybrid materials and the architectured materials that contain highly controlled structures. Structure control allows to change the variety of possible geometries and opens up a number of other useful properties. Therefore, this thesis also deals with the mechanical alloying and SPS. The experimental part describes procedures of preparation of four samples of composites with a duplex structure from a powder of a significantly tough alloy (austenitic steel 316L) in combination with a powder of a significantly strong alloy (titanium carbonitride). A crucial part of this thesis is characterization of these four samples by electron microscopy methods (SEM, TEM, EDS) and supported by hardness measuring.
Mechanical properties of Al alloy prepared by SLM process
Vitásek, Ladislav ; Štěpánek, Roman (referee) ; Pantělejev, Libor (advisor)
The master's thesis deals with properties of aluminium alloys prepared by SLM process. The teoretical part of thesis is focused on decribtion of selective laser melting technology, metallurgical defects and mechanical properties of aluminium alloys processed by this technology. The experimental part of this thesis deals with selections of the SLM process parameters suitable for samples preparation in bulk. Tensile testing at room temperature was used for evaluation of basic mechanical properties. Metallographic and fractographic analyses were performed for evaluation of the microstructure and fracture mechanisms. The materials characteristics obtained on SLM samples were compared with the properties of the same materials grade produced by conventional technologies.
Fatigue endurance of extruded Mg alloy AZ91E
Sobola, Petr ; Štěpánek, Roman (referee) ; Pantělejev, Libor (advisor)
This thesis deals with fatigue behaviour of magnesium alloy AZ91E produced by extrusion. In the frame of this work, basic mechanical characteristics and data from performed fatigue tests were obtained. Further metallographic analysis of microstructure and fractographic analysis of broken specimens after fatigue tests were carried out.
Mechanical properties of materials prepared by SLM process
Nopová, Klára ; Štěpánek, Roman (referee) ; Pantělejev, Libor (advisor)
The final thesis determined the properties of alloys formed from mixtures of powders processed by the SLM method. Powders of alloy AlSi12 and EN AW 2618 were fused in the proportion 75 wt. % AlSi12 + 25 wt. % 2618, 50 wt. % AlSi12 + 50 wt. % 2618 and 25 wt. % AlSi12 + 75 wt. % 2618. Metallographic analysis, EBSD analysis and line EDS microanalysis were made on the samples. Tensile test at room temperature and hardness were carried out to determine the mechanical properties. Fractographic analysis was performed after tensile test.
Possibilities of using cold gas dynamic spray (Cold Spray) in military applications
Dvořáček, Jan ; Štěpánek, Roman (referee) ; Řehořek, Lukáš (advisor)
This work aims to acquaint with thermal spray method called Cold spray. This method is used for repair of expensive and badly replaceable components, which are mainly used in aerospace and military branch of industry. These repairs cause economic savings, higher accuracy and quality than other thermal spray methods. There is a possibility to use Cold spray for ballistic armor production. It is possible that ballistic protection would have higher ballistic efficiency, durability and coherence. The second part of the work handle with the evaluation of the interface of a metal-ceramic two-layer ballistic protection system made by the cold spray method. The evaluation was performed in the form of light and electron microscopy.

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2 Štěpánek, Robert
1 Štěpánek, Robert Benno
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