National Repository of Grey Literature 40 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Welding of 22MnB5 steel using Laser-TIG hybrid technology
Krejčí, Adam ; Sigmund, Marián (referee) ; Mrňa, Libor (advisor)
This thesis deals with usage of hybrid technology Laser-TIG for welding of boron enhanced steel 22MnB5. This thesis evaluates the influence of preheating using technology of TIG arc welding to a weld quality in comparison with laser welds. In practical part of thesis there were 1,8 mm metal sheets of 22MnB5 welded. This metal sheet specimens were welded by using constant parameters of laser with varying parameters of TIG technology. There were 12 specimens of sheet metal created including 3 specimens using only laser and 9 specimens using Laser-TIG hybrid technology while varying magnitude of current (I=20 A, 40 A a 60 A). Welds created this way were evaluated by tensile test and strength limits compared. Then metalografic survey was carried out examining macro and microstructure. Results of metalografic survey were confronted with Vickers hardness test.
Thermal spray by electric arc
Eliáš, Vojtěch ; Sigmund, Marián (referee) ; Kubíček, Jaroslav (advisor)
This thesis deals with the issue of thermal spraying by means of an electric arc. First of all, a theoretical part is processed using a literary study dealing with corrosion and thermal spraying technology. The experimental part contains a description of the technological procedure and evaluation of four thermally sprayed samples. Zinacor 850, consisting of 85% zinc and 15% aluminum, was used as a coating. The evaluation involves measurements of thickness, adhesion and roughness as well as the macro-structural analysis of the coating. Two samples showed unusually low adhesion, and all samples also had a large fluctuation of the measured thicknesses. This was also confirmed by the macro-structural analysis, which showed that the sample with low adhesion also had high porosity. These defects may have multiple causes, but the recommendation for further practice is to reduce the spraying distance from the base material.
Welding of martensitic stainless steel using hybrid technology Laser - TIG
Novotný, Jan ; Sigmund, Marián (referee) ; Mrňa, Libor (advisor)
Theoretical part of this thesis includes overview of laser welding technology and possible combinations with arc welding methods for meeting desired properties of the weld. It also explains mechanical testing and metallographic examination on welds. The experimental part deals with optimisation of process parameters during welding of martensitic stainless steel, used in energetic industry using hybrid laser - TIG technology in regard of mechanical properties of the weld, its structure and proposal of technological parameters.
Welding of deep-drawing steels with a protective layer by means of an oscillating laser beam
Holub, Kamil ; Sigmund, Marián (referee) ; Mrňa, Libor (advisor)
This thesis deals with the topic of procedural parameters influence on the properties of welded joint in zinc-coated deep-drawing steels in laser welding with wobbling. First part of the thesis serves as an overview of laser welding technology, welding of steel with protective zinc layer and weld quality testing. Second part is dedicated to a proposal, process flow and evaluation of an experiment. Seven trial lap welding joints of DC04+ZE steel have been welded using different welding parameters. Specimens from these trial welds were used for metallurgical testing by macro-etch examination and for tensile strength break testing to get mechanical properties of welded joints.
Welding of deep-drawing steels with protective layer by laser-TIG hybrid technology
Brehovský, Patrik ; Sigmund, Marián (referee) ; Mrňa, Libor (advisor)
The diploma thesis focuses on laser welding of extra deep-drawn steel sheet according to the standard WSS-M1A365-A14 with a protective zinc surface layer. A 0,9 mm thick steel sheet with a zinc layer with coating weight 50 g · m^-2 is welded by a hybrid welding method Laser-TIG. The laser, as the primary energy source, is used for welding the material. The arc, provided by a non-melting tungsten electrode, is used for preheating the material for melting and evaporation of the zinc layer. Based on the initial experiments, the magnitude of the laser power with the welding speed was chosen as a constant parameter. The magnitude of the electric current, as the variable parameter, was set up to 0, 20, 30 and 40 ampers for welding the lap and the butt welds. Only one piece of the each weld type combination was made. The welds were afterwards tested to verify their quality and material properties. The first differences between laser welding with or without TIG preheating were visible during the experiment. The positive effects of the laser welding with preheating by TIG were confirmed. The material properties of the joints achieved better values and a influence of the welding defects on the quality of the joints was reduced. The Laser-TIG is a good choice for welding galvanized steel sheets in the mass production of automotive industry and it could be improved by more researches.
Welding parameters optimalization of robotic welding for car industry
Soprunenko, Valeriia ; Mrňa, Libor (referee) ; Sigmund, Marián (advisor)
Thesis deals with individual technology of new welding processes "specifically FRONIUS TPSi". The greatest emphasis is on welding technology, especially on the differences between the individual methods. The experimental part of the thesis is focused on finding suitable parameters for welding filled welds.Everythingwith respect to required welds quality welded by robotic welding. The samples were evaluated in terms of penetration depth, amount of heat introduced and the number of defects.
Evaluation of quality welds on chains for harvester
Teuer, Tomáš ; Kubíček, Jaroslav (referee) ; Sigmund, Marián (advisor)
The diploma thesis examines the influence of setting welding parameters and welding process on the resulting structure and strength of the welded joint of harvester chains. The theoretical part discusses the problem of weldability of pine steels by using method “135” with the possibility of destructive or non-destructive testing of welded joints. In the practical part, this matter is examined on a specific weldment, the harvester chain. Cross member with a cube welded in two ways by method 135, followed by an assessment of the performance of welds. The results of the evaluation are written down in the manual.
Weldability of cobalt alloys by hybrid method Laser-TIG
Herčík, Tomáš ; Mrňa, Libor (referee) ; Sigmund, Marián (advisor)
The master thesis summarizes the critical situation of the lack of a cobalt used in different industry branches. Due to its increasing price, it will not be possible to use in existing applications. One of these applications is production of cobalt alloys where the replacement of this element is impossible. This type of material keeps mechanical properties at high temperature. However, a suitable choice of technology can achieve at least its savings. In the field of welding, the alloys are joined without any use of an additional material. The possible solution could be the use of hybrid technologies or electron beam. Verification of weldability of both methods was realised in experimental parts and evaluated by destructive methods. The investigation was performed on wear resistant alloy Stellite 6B.
Welding thin-walled pipes made of stainless steels
Naď, Tomáš ; Sigmund, Marián (referee) ; Kubíček, Jaroslav (advisor)
The bachelor's thesis deals with technology of welding of thin-walled stainless steel pipes and the analysis of weldability of stainless steels. The theoretical part provides a basic description of the material's weldability and the basic defects in welding, the characteristics of stainless steels, their division, marking, alloying and a general overview of their weldability. The experimental part describes selected welding technologies used for the production of thin-walled stainless steel pipes (LBW, PAW, HFIW). Finally, the technology used to weld the presented samples of thin-walled pipes is ascertained and the macrostructure of the weld are compared.
Welding the frame of the tandem bicycle
Rajm, Vojtěch ; Sigmund, Marián (referee) ; Kubíček, Jaroslav (advisor)
In the first part of thesis were compared frames of two different bicycles and according to this comparison was designed a geometry of tandem bicycle. In a next part were described the most common materials in cycling industry and theirs advantages and disadvantages. According to the comparison, the steel EN 25CrMo was considered as the most suitable material for its low prize and high strength. After that is described weldability of steels and types of cracks which are one of the most casual defects in welded materials. In another part of thesis are theoretically described kinds of suitable welding methods for bicycle frames. As the most suitable are methods in shielding gases MIG/MAG and TIG. As the best method was chose TIG welding. In a practical part of thesis are compared these methods experimentally. Tubes from selected material were welded by MAG and TIG. The TIG welding proved again as better because of deeper and tough welds.

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