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Diffusion of carbon in welding joints of low alloys and high alloy steels.
Zdvořáček, Marek ; Rek, Antonín (referee) ; Stránský, Karel (advisor)
Content of a document result measurements and analysis carbon´s diffusion at welding joint created from hight alloyed austenitic steel CSN 417242 and not alloyed steel CSN 412 050. Samples have been put throught isothermal anneal in a temperature range 500 °C up to 1100°C. Aim one´s effort to metalographyic quantification carburized and uncarburized zone. The next part of the document content measuring x-ray energy through microanalysis, where has been record course of a carbon disintegration and selected replacements elements at whole length of the welding joint . At the end of experimental part has been gauged course microhardness HV 0,05 at whole lenght of welding joint, from an acquired data has been chose the most optimal temperature of isothermal anneal, to produce the smallest structural notch.
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Local tests of mechanical properties of materials
Wasserbauer, Jaromír ; Šoukal, František (referee) ; Zmrzlý, Martin (advisor)
This thesis deals with measurement of hardness and microhardness in relation to structure of homogeneous and heterogeneous materials. In the introduction basic theoretical background is commented, i.e. definitions, terminology, principles of measuring techniques for estimation of hardness, microhardness, tensile strength, compressive strength and bending strength. Follows a brief review of present research results focused on use of described principles in materials engineering. Then the experimental equipment and sample preparation is described. The crucial part of the thesis is summary of achieved results of original measurement and discussion of their relations to each other. Finally, the groundbreaking estimation is described, showing the correlation of chemical composition gradient and mechanical properties in interfacial zone of geopolymeric material.
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Nickel coatings and their properties
Buchtík, Martin ; Tkacz, Jakub (referee) ; Zmrzlý, Martin (advisor)
The aim of the bachelor’s thesis was summary of existing knowledge concerning to electroless deposition of nickel coatings and their properties. In the theoretical part there are two chapters. In the first chapter present knowledge of chemical nickel plating is described in details. It also discuss mechanisms of this type of coating and individual components of nickel plating bath. In the second chapter there is summarized knowledge of composite coatings deposition and description of their mechanical properties. The experimental part deals with deposition of composite coatings on steel substrates and heat treatment of Ni-P coatings. Dependence of microhardness on temperature of heat treatment was studied and then there is also described dependence of microhardness on duration of heat treatment. Deposited coatings, their morphology and composition were studied using scanning electron microscope and EDS analysis. The values of microhardness of both types of coatings were measured and compared using microhardness tester.
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Fatigue behaviour of nickel-based superalloy IN738LC with AlSi coating at 800°C
Hlavnička, Radek ; Juliš, Martin (referee) ; Hutařová, Simona (advisor)
This work deals with influence of applied protective AlSi layer on low cycle fatigue behaviour of substrate from nickel base superalloy Inconel 738 LC. Protective layer is made by thermal spraying, plasma spraying followed by heat treatment. The emphasis is especially concentrated to the microstructure evaluation of the protect layer and basic material, in addition, measurement of layer thickness and the microhardness in as sprayed conditions and after heat treatment. The fatigue behaviour is assessed by fracture area observation and fatigue cracks evaluation after low cycle fatigue tests carried out at 800 °C.
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Present Trends of Methods for Hardness Measurement
Brzobohatý, Tomáš ; Doležal, Pavel (referee) ; Hutařová, Simona (advisor)
Purpose of this thesis is created view of present methods of hardness measurement and to describe them in more detail. Firstly this thesis deals with representatives of standard and for many years used methods of hardness measurement and hardness evaluation which are used today, too. Secondly this thesis is focused on modern methods, and their successful working experience is question of time.
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Surface strengthening of a stainless steel using pulsating water jet technology - evaluation by means of microhardness measurements
Hloch, Sergej ; Ščučka, Jiří ; Lehocká, D. ; Simkulet, V.
Results of an experiment focused on surface strengthening of AISI 304 stainless steel using pulsating water jet technology is presented in the paper. The tested material was subjected to the action of pulsating water jet under changing technological conditions (water pressure, traverse speed, stand-off distance, and diameter of nozzle orifice). Microhardness measurements at various distances from the created traces were applied for assessing the material strengthening. Based on the results, it can be stated that the dynamic effects of pulsating water jet on the tested steel samples cause the material deformations leading to the formation of a zone of strengthened material along the disintegrated area.
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Hodnocení mechanických vlastností částicových polymerních kompozitů pomocí měření mikrotvrdosti
Minster, Jiří ; Berka, L. ; Hristova, J.
The applicability of Vickers microhardness measurements for mechanical assessment of heterogeneous polymer composites (filled polymer composites and polymer concretes) is discussed. Two types of composites based on epoxy and polyester matrices were investigated and two types of finely dispersed fillers were used with the 20% volumetric concentration of the individual fillers. The reinforcing effect of the hard filler and changes in the microhardness (i.e. in the yield strengths and moduli) in the neighbourhood of filler micrograins have been substantiated.
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Vliv tepelného zpracování na mechanické vlastnosti slitiny FeNiB
Zábranský, Karel ; Jirásková, Yvonna
An influence of thermal treatment in the temperature range 150 - 350 °C on the structural and mechanical properties of an amorphous FeNiB alloy is investigated. The high tensile strength of 2200 MPa in the as-prepared amorphous state slightly decreases with increasing annealing temperature up to approximately 200 °C in opposite to microhardness where an increase is observed. Above 200 °C a pronounced deterioration of both characteristics is observed which reflects the embrittlement of amorphous structure without any indication of crystallization.
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Improvement of mechanical properties of the sintered ceramics by plasma remelting
Ctibor, Pavel
Ways how to improve mechanical properties on a surface of bulk ceramics are drawn. In the experiments the author reach surface treatment by plasma torch producing thermal plasma and usually utilized for plasma spraying. Commercial bulk ceramic materials produced via sintering or casting were tested. The materials were members of ternary systems magnesia - alumina - silica and zirconia - alumina - silica. Before and after thermal treatment the microstructure was studied and the microhardness was measured on materialographically polished cross sections using Vickers indentation (HV) in surfacial layers and also deep inside the bulk body. Slurry abrasion resistance (SAR) was determined according ASTM G 75 standard. Various degree of improvement of HV and SAR was detected on treated samples. The microstructural character of completely remolten surfacial layer, partly influenced intermediate layers and original bulk body is discusses in connection with evaluated mechanical tests.
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