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Effect of material thickness on the width and properties of the heat-affected zone
Horák, Tomáš ; Slováček, Marek (referee) ; Kubíček, Jaroslav (advisor)
Thess deals with the welding of high-strength steel by the MAG method and the evaluation of structural and dimensional changes depending on the thickness of the material. CREUSABRO 4800 steel was chosen using MEGAFILL 742 M additive material. A weld was created with welding parameters of 130 A, 20.7 V and a feed speed of 35 cm/min with a swing of 7 m, on steel with a thickness of 3, 6, 10 mm. Subsequently, a weld was made on samples with a thickness of 10 mm with welding parameters of 300 A, 28.8 V, 35 cm/min with a swing of 7 mm, while one of the samples was preheated to the recommended temperature. The resulting macro structure, micro images and the thermally affected area were evaluated.
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Oxigen cutting of high strength steels
Lupták, Jakub ; Izák, Josef (referee) ; Kubíček, Jaroslav (advisor)
The work focuses on the issue of thermal cutting and its use for high-strength steels. Plasma cutting is most commonly used for cutting these materials, and this work explores the alternative possibility of cutting with oxygen. The theoretical part discusses high-strength steels, the possibilities of their thermal cutting, the selection of methods for the practical part, and their principles of operation. Specific methods for the experimental part are selected and detailed in terms of their principles of operation. The experimental part involves cutting selected samples of high-strength steels using oxygen and plasma at two different cutting speeds. Changes in hardness at the cutting edge are analyzed, and the size of the heat-affected zone for both technologies is evaluated. Finally, the suitability of oxygen cutting technology for high-strength steels is assessed.
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Welding of finegrain steel from range of DOMEX steel by YbYAG fiber laser.
Němeček, Tomáš ; Daněk, Ladislav (referee) ; Mrňa, Libor (advisor)
The project elaborated within the engineering studies of the branch Manufacturing technology presents an experiment of welding of high strength steel by fiber laser. The project includes a theoretical study, which deals with the welding material properties, principles and types of lasers and laser welding technology. The practical part contains a verification of the welding parameters according to the standard ČSN EN ISO 15614-11. The final evaluation results of the experiment at the close of the project are presented.
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Steel-Concrete Columns Composed of High-Strength Materials
Röder, Václav ; Štěpánek, Petr (referee) ; Studnička,, Jiří (referee) ; Vičan,, Josef (referee) ; Karmazínová, Marcela (advisor)
The main objective of this thesis is the verification of the buckling strength of the composite compression members which were made from high-strength materials. This thesis is divided into four main chapters which are interconnected. The first chapter summarizes the current state of the problem of the compression members. The basis of this part is the elementary theories and researches, the task of this text is attempted to understand and obtain normative procedures which are important for practical use. The second part deals with the theoretical analysis of composite column, mainly with the examination of the individual effects on the buckling strength. The result of the first and the second parts is analytical algebraic equations which determine the buckling strength of the member. The third part contains the numerical analysis, which leads to create a numerical model of the compression column. The numerical model is used for the verification of the theoretical analysis and for the investigation of the behaviour of the column loaded by axial force. The last part deals with the experimental verification of the previous analyses. There are tested various types of the composite columns, which were made of steel with a yield strength up to 455 MPa and of the concrete with a cube compression strength up to 102 MPa. Experimental results confirmed the high reliability of centrally loaded column and every tested columns failed by flexural buckling. The final step is evaluation and comparison of the results obtained from previous four parts. It was founded that design criteria for centrally loaded steel-concrete column are too conservative and design relationships doesn´t use the positive properties of high-strength materials for economic design.
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Study of properties of laser welds of Domex 460 MC material using arc preheating
Novotný, Michal ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This diploma thesis deals with weldability of Domex 460 MC material. There are two welding methods and three other welded materials in heterogenous connection which will be researched in this diploma thesis. The welding methods are fiber solid-state laser and a new method of hybrid welding called laser – TIG. The other materials are Domex 700 MC, S355J2 and DC01. Domex 460 MC is a high-strenght steel with fine-grained structure. During the welding process the imput heat decreases mechanical properties of the materials. This effect is caused by material seeds growing. From these samples (which were produced by welding) were created metallographic cuts. These metallographic cuts were analysed focusing on their makrostructure, microstructure, mikrohardnest and Mn arrangement in welded heterogenous samples using electron microscope and EDX analysis.
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Welding of USIBOR 1500 steel by YbYAG fiber laser.
Bogar, Radek ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
The use of high-strength steel is more and more frequent in the car industry. I focused on USIBOR® 1500 steel welded by Nd-YAG laser. For my experiment, there were used various welding parameters and shielding gases. To compare the weld samples, I used the tensile, bending, macrostructure, microstructure and Vickers hardness test with different combinations of thickness as well as welded material.
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Study of properties of laser welds of Domex 460 MC material using arc preheating
Novotný, Michal ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
This diploma thesis deals with weldability of Domex 460 MC material. There are two welding methods and three other welded materials in heterogenous connection which will be researched in this diploma thesis. The welding methods are fiber solid-state laser and a new method of hybrid welding called laser – TIG. The other materials are Domex 700 MC, S355J2 and DC01. Domex 460 MC is a high-strenght steel with fine-grained structure. During the welding process the imput heat decreases mechanical properties of the materials. This effect is caused by material seeds growing. From these samples (which were produced by welding) were created metallographic cuts. These metallographic cuts were analysed focusing on their makrostructure, microstructure, mikrohardnest and Mn arrangement in welded heterogenous samples using electron microscope and EDX analysis.
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Steel-Concrete Columns Composed of High-Strength Materials
Röder, Václav ; Štěpánek, Petr (referee) ; Studnička,, Jiří (referee) ; Vičan,, Josef (referee) ; Karmazínová, Marcela (advisor)
The main objective of this thesis is the verification of the buckling strength of the composite compression members which were made from high-strength materials. This thesis is divided into four main chapters which are interconnected. The first chapter summarizes the current state of the problem of the compression members. The basis of this part is the elementary theories and researches, the task of this text is attempted to understand and obtain normative procedures which are important for practical use. The second part deals with the theoretical analysis of composite column, mainly with the examination of the individual effects on the buckling strength. The result of the first and the second parts is analytical algebraic equations which determine the buckling strength of the member. The third part contains the numerical analysis, which leads to create a numerical model of the compression column. The numerical model is used for the verification of the theoretical analysis and for the investigation of the behaviour of the column loaded by axial force. The last part deals with the experimental verification of the previous analyses. There are tested various types of the composite columns, which were made of steel with a yield strength up to 455 MPa and of the concrete with a cube compression strength up to 102 MPa. Experimental results confirmed the high reliability of centrally loaded column and every tested columns failed by flexural buckling. The final step is evaluation and comparison of the results obtained from previous four parts. It was founded that design criteria for centrally loaded steel-concrete column are too conservative and design relationships doesn´t use the positive properties of high-strength materials for economic design.
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Welding of USIBOR 1500 steel by YbYAG fiber laser.
Bogar, Radek ; Kubíček, Jaroslav (referee) ; Mrňa, Libor (advisor)
The use of high-strength steel is more and more frequent in the car industry. I focused on USIBOR® 1500 steel welded by Nd-YAG laser. For my experiment, there were used various welding parameters and shielding gases. To compare the weld samples, I used the tensile, bending, macrostructure, microstructure and Vickers hardness test with different combinations of thickness as well as welded material.
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Welding of finegrain steel from range of DOMEX steel by YbYAG fiber laser.
Němeček, Tomáš ; Daněk, Ladislav (referee) ; Mrňa, Libor (advisor)
The project elaborated within the engineering studies of the branch Manufacturing technology presents an experiment of welding of high strength steel by fiber laser. The project includes a theoretical study, which deals with the welding material properties, principles and types of lasers and laser welding technology. The practical part contains a verification of the welding parameters according to the standard ČSN EN ISO 15614-11. The final evaluation results of the experiment at the close of the project are presented.
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