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Quantification of Hydraulic Descaling Mechanisms
Hrabovský, Jozef ; Toman,, Zdeněk (referee) ; Dobeš, Ferdinand (referee) ; Horský, Jaroslav (advisor)
The issue of descaling is an important part of the forging and heat treatment of steel and semi products of steel production. Rising of new information and study of this process can increase efficiency and improve the surface quality after descaling. This thesis is focused on the mechanisms of the high pressure hydraulic descaling qualification and study of the chemical compounds of which the scales grown. To achieve all goals of this work and to get a comprehensive view of descaling process, few experimental measurements and numerical analyses were performed. All experimental measurements were focused on obtaining data about fundamental parameters and effects of the hydraulic descaling. The data obtained from measurements were applied to numerical analyses, which aimed to discover a deeper relation and to confirm the experimental results. This thesis can be divided into two main parts. The first part is devoted to parameters of the water jet study. The main studied characteristics of the high pressure hydraulic water jet were heat transfer coefficient and impact pressure at different modes such as standard or pulsating water jet. Experimentally measured data of these parameters were applied in numerical analyses. The numerical analyses were focused on studying the impact of the water jet parameters on the stresses in the oxide scale layers. A further water jet analysis was focused on the influence of the individual parts of the hydraulic system (such as water chamber or stabilizer) on its characteristics. In this part different types of the water chambers in combination with different types of stabilizers on the impact pressure values were investigated. These measurements were supported by fluid flow analysis through the hydraulic system. The second part of this work was focused on getting mechanical properties of the oxide scales from specimens prepared from standard structural steel and specimens from silicon steel. In this thesis, the influence of various parameters and characteristics was studied on these two types of steel. Mechanical properties of oxide scale structures were carried out by the Small Punch Test method. To obtain the fundamental mechanical properties such as Young´s modulus, yield strength and ultimate strength, material parameters based on the measured data were optimized. The whole work was carried out in order to get valuable and comprehensive results about high pressure hydraulic descaling process and influencing factors as well as about oxide scales themselves.
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Oxide scales damaging evaluation
Audyová, Markéta ; Vejvoda, Stanislav (referee) ; Lošák, Pavel (advisor)
This work is focused on oxide scale failure and characteristics created in high temperature – supercritical processes. The presence of high temperature corrosion in supercritical processes is minimalised by selection of the right material. For this work was selected material X10CrMoVNb9-1, where formulas of present oxidation scales are Fe2O3, Fe3O4 and FeCr2O4. Each oxidation scale has its own mechanical properties thus it is important to notice scale arrangement, thickness and geometry. Oxide scale mechanical properties, scale failure mechanisms and oxidation scale growth is evaluated in this work. Tension and pressure oxide scale failure are determined by critical values, which are mentioned in this work. Thanks to these values there was possibility to verify the authenticity of the finite element model. Oxidation scales created in heat exchangers are badly accessible thus it is difficult to observe them or remove them mechanically. Tube finite element model with oxidation scales was created in this work. There are simulations of scales on selected steel in supercritical conditions (pressure 24 MPa, temperature 500 °C). Simulation and analytic results are compared. Failure operative conditions are searched for scale FeCr2O4 until its compleate delamination and separation from metal. Aim of this work is to create an oxidation scale model with a possibility of futher use.
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Oxide scales damaging evaluation
Audyová, Markéta ; Vejvoda, Stanislav (referee) ; Lošák, Pavel (advisor)
This work is focused on oxide scale failure and characteristics created in high temperature – supercritical processes. The presence of high temperature corrosion in supercritical processes is minimalised by selection of the right material. For this work was selected material X10CrMoVNb9-1, where formulas of present oxidation scales are Fe2O3, Fe3O4 and FeCr2O4. Each oxidation scale has its own mechanical properties thus it is important to notice scale arrangement, thickness and geometry. Oxide scale mechanical properties, scale failure mechanisms and oxidation scale growth is evaluated in this work. Tension and pressure oxide scale failure are determined by critical values, which are mentioned in this work. Thanks to these values there was possibility to verify the authenticity of the finite element model. Oxidation scales created in heat exchangers are badly accessible thus it is difficult to observe them or remove them mechanically. Tube finite element model with oxidation scales was created in this work. There are simulations of scales on selected steel in supercritical conditions (pressure 24 MPa, temperature 500 °C). Simulation and analytic results are compared. Failure operative conditions are searched for scale FeCr2O4 until its compleate delamination and separation from metal. Aim of this work is to create an oxidation scale model with a possibility of futher use.
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Quantification of Hydraulic Descaling Mechanisms
Hrabovský, Jozef ; Toman,, Zdeněk (referee) ; Dobeš, Ferdinand (referee) ; Horský, Jaroslav (advisor)
The issue of descaling is an important part of the forging and heat treatment of steel and semi products of steel production. Rising of new information and study of this process can increase efficiency and improve the surface quality after descaling. This thesis is focused on the mechanisms of the high pressure hydraulic descaling qualification and study of the chemical compounds of which the scales grown. To achieve all goals of this work and to get a comprehensive view of descaling process, few experimental measurements and numerical analyses were performed. All experimental measurements were focused on obtaining data about fundamental parameters and effects of the hydraulic descaling. The data obtained from measurements were applied to numerical analyses, which aimed to discover a deeper relation and to confirm the experimental results. This thesis can be divided into two main parts. The first part is devoted to parameters of the water jet study. The main studied characteristics of the high pressure hydraulic water jet were heat transfer coefficient and impact pressure at different modes such as standard or pulsating water jet. Experimentally measured data of these parameters were applied in numerical analyses. The numerical analyses were focused on studying the impact of the water jet parameters on the stresses in the oxide scale layers. A further water jet analysis was focused on the influence of the individual parts of the hydraulic system (such as water chamber or stabilizer) on its characteristics. In this part different types of the water chambers in combination with different types of stabilizers on the impact pressure values were investigated. These measurements were supported by fluid flow analysis through the hydraulic system. The second part of this work was focused on getting mechanical properties of the oxide scales from specimens prepared from standard structural steel and specimens from silicon steel. In this thesis, the influence of various parameters and characteristics was studied on these two types of steel. Mechanical properties of oxide scale structures were carried out by the Small Punch Test method. To obtain the fundamental mechanical properties such as Young´s modulus, yield strength and ultimate strength, material parameters based on the measured data were optimized. The whole work was carried out in order to get valuable and comprehensive results about high pressure hydraulic descaling process and influencing factors as well as about oxide scales themselves.
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Quantification of Hydraulic Descaling Mechanisms
Hrabovský, Jozef ; Horský, Jaroslav (advisor)
The issue of descaling is an important part of the forging and heat treatment of steel and semi products of steel production. Rising of new information and study of this process can increase efficiency and improve the surface quality after descaling. This thesis is focused on the mechanisms of the high pressure hydraulic descaling qualification and study of the chemical compounds of which the scales grown. To achieve all goals of this work and to get a comprehensive view of descaling process, few experimental measurements and numerical analyses were performed. All experimental measurements were focused on obtaining data about fundamental parameters and effects of the hydraulic descaling. The data obtained from measurements were applied to numerical analyses, which aimed to discover a deeper relation and to confirm the experimental results. This thesis can be divided into two main parts. The first part is devoted to parameters of the water jet study. The main studied characteristics of the high pressure hydraulic water jet were heat transfer coefficient and impact pressure at different modes such as standard or pulsating water jet. Experimentally measured data of these parameters were applied in numerical analyses. The numerical analyses were focused on studying the impact of the water jet parameters on the stresses in the oxide scale layers. A further water jet analysis was focused on the influence of the individual parts of the hydraulic system (such as water chamber or stabilizer) on its characteristics. In this part different types of the water chambers in combination with different types of stabilizers on the impact pressure values were investigated. These measurements were supported by fluid flow analysis through the hydraulic system. The second part of this work was focused on getting mechanical properties of the oxide scales from specimens prepared from standard structural steel and specimens from silicon steel. In this thesis, the influence of various parameters and characteristics was studied on these two types of steel. Mechanical properties of oxide scale structures were carried out by the Small Punch Test method. To obtain the fundamental mechanical properties such as Young´s modulus, yield strength and ultimate strength, material parameters based on the measured data were optimized. The whole work was carried out in order to get valuable and comprehensive results about high pressure hydraulic descaling process and influencing factors as well as about oxide scales themselves.
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