Browsing by Author "Kik, Tomasz"

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    Application of Numerical Simulations on 10GN2MFA Steel Multilayer Welding
    (SPRINGER INTERNATIONAL PUBLISHING AG, GEWERBESTRASSE 11, CHAM, CH-6330, SWITZERLAND, 2019-09-27) Kik, Tomasz; Moravec, Jaromír; Nováková, Iva
    10GN2MFA steel is used to produce wire and manufacturing of steam generators, pressure compensators, collectors and other equipment for nuclear power plants. In this area, there is no place to do any mistakes during manufacturing or carrying out extensive tests and producing a lot of prototypes. It is the main reason whywe usedmodern software for numerical simulation ofwelding and heat treatment processes also on the very early stage of development. The aim of this paper is to describe how can welding processes be optimized by means of the numerical simulations mainly with respect to the structural changes, stresses and hardness distribution in the Heat Affected Zone (HAZ). On the real multilayer weld how to arrange whole experiment in order to obtain not only relevant input data but also verification data will be described. Additional aim of this paper is to propose mathematical description of the computational model that is usable for simulation computations of welding and heat treatment of real structure components.
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    Application possibilities of the low-temperature repairs on creep-resistance turbine components from material GX23CrMoV12-1
    (2018-01-01) Moravec, Jaromír; Nováková, Iva; Sobotka, Jiří; Kik, Tomasz
    Papers deals with the problems of repairs at new and also already loaded components of steam and gas turbines. Generally, it is about welding repairs at valve and turbine chambers, transmitters, vane carriers, tripping valve body and so on. There are both technological defects caused by casting (e.g. shrinkage cavities, misruns, porosity and cracks) and defects caused by operation (thermal-stress fatigue, incorrect method of operation, etc.). Many of the mentioned defects take effect not until the final technological method - mostly at machining. However, in this production phase it is not possible to get form the supplier new production elements due to economical and also delivery time reasons. All of that results in delay of production and penalty. As the major aim of this paper, there was to find such repairs techniques which can ensure serviceability of mentioned devices under the standard regime. In these cases is needed to use much lower tempering temperature than under the standard production, mainly because of necessity to eliminate deformation caused by heating of part that is not possible to be subsequently removed by machining.
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    Experiments and Numerical Simulations of the Annealing Temperature Influence on the Residual Stresses Level in S700MC Steel Welded Elements
    (MDPI, 2020-01-01) Kik, Tomasz; Moravec, Jaromír; Švec, Martin
    The article presents the results of research on the influence of temperature and time changes of the annealing process on the values and distribution of stresses in the simulated heat-affected zone of S700MC steel welded joints. For this purpose, tests were carried out on a thermal cycle simulator, as well as heating the prepared samples in accordance with the recorded welding thermal cycles, and then annealing at temperatures from 200 to 550 °C. The stresses values in the tested samples before and after the annealing process were measured by using X-ray diffraction (XRD). The performed tests were verified with the results of numerical analyses using the finite element method (FEM) performed in the VisualWeld (SYSWELD) environment as, on the one hand, the verification of the obtained results, and, on the other hand, the source of data for the development of a methodology for conducting analyses of heat treatment processes of S700MC steel welded structures. Also presented are three examples of numerical analyses for Gas Metal Arc (GMAW), laser and hybrid welding and then the annealing process of the obtained joints at selected temperatures. The main purpose of the work was to broaden the knowledge on the influence of annealing parameters on the values and distribution of stresses in welded joints, but also to signal the possibility of using modern software in engineering practice.
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    NUMERICAL SIMULATIONS OF X22CrMoV12-1 STEEL MULTILAYER WELDING
    (POLSKA AKAD NAUK, POLISH ACAD SCIENCES, INST METALL & MATER SCI PAS, PL, 00-901 WARSZAWA, POLAND, 2019-01-01) Kik, Tomasz; Moravec, Jaromír; Nováková, Iva
    The aim of this paper is to present the procedure test for calibration and validation of the numerical model for X22CrMoV12-1 steel multilayer welding. On the real multilayer weld was described how to arrange the whole experiment in order to obtain not only relevant input data but also verification data. Tests on a specially prepared specimen, welded with 8 beads in 4 layers, allows to determine the actual geometry of the single welded beads, registration of welding thermal cycles and the hardness distribution in successively deposited beads together with determining the heat influence of subsequent layers. The results of the real welding tests were compared with the results obtained from the numerical simulations and extended by the calculated stresses and distortions distributions of the tested specimen. A new, improved hardness prediction algorithm for high-alloy martensitic and bainitic steels was also proposed.
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    Possibilities of using interlayers during diffusion welding of Ti Gr2 and AISI 316L
    (2018-01-01) Moravec, Jaromír; Nováková, Iva; Kik, Tomasz
    Joining of materials with different physical and mechanical properties is always very problematic. As one of the possibilities, there can be used method of joint creation in solid state - e.g. by the diffusion welding. With this method it is possible to joint very different materials - even metals with non-metals. Despite the unquestionable advantages of this method, there is necessary to take into account also its limits. Among of them, there is creation of brittle intermetallic phases on the boundary of materials. This occurs e.g. at creation heterogeneous joints between titanium and highly- alloyed austenitic steel. The major aim of this paper is to describe how it is possible to eliminate brittle intermetallic phases created on boundary between Ti Grade 2 and AISI 316L steel by using metal interlayers.