Wyniki wyszukiwania - BazTech

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Thermophysical properties of 904L austenitic steel

Nasiłowska B., Bogdanowicz Z., Terpiłowski J., Pańcikiewicz K.

Metallurgy and Foundry Engineering

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2018

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Vol. 44, no. 2

61--71

EN

This paper presents the results of the structural investigations and thermophysical properties of 904L steel parent material. Experimental studies on the structure of 904L steel proved a pure austenitic structure. Both the experimental research and analysis of the thermophysical properties of 904L steel were complemented with the results of the thermal conductivity calculations for the tested material. The paper presents a brief description of the measurements, the procedures for evaluating the data, and a set of the obtained results.

PL

W pracy przedstawiono wyniki badań strukturalnych i właściwości cieplnofizyczne materiału rodzimego stali 904L. Badania eksperymentalne struktury stali 904L wykazały strukturę czysto austenityczną. Badania doświadczalne i analizę właściwości cieplnofizycznych stali 904L uzupełniono wynikami obliczeń przewodności cieplnej badanego materiału. W pracy przedstawiono zwięzły opis wykonywanych pomiarów, charakterystykę procedur opracowania danych oraz komplet uzyskanych wyników.

2

TIG and laser beam welded joints – simplified numerical analyses

Nasiłowska B., Derewońko A., Bogdanowicz Z.

Journal of Theoretical and Applied Mechanics

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2018

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Vol. 56 nr 3

645--656

EN

Regardless of the welding method, a new joint and the surrounding area are inevitably subjected to thermo-physical perturbation. The paper presents analyses of many diﬀerent issues involved in welding and potential solutions including adoption of simplifying assumptions, application of numerical algorithms and development of reliable representative models. The Finite Element Method is used to determine residual stress distribution, using results from thermo-physical tests and widely known mechanical properties of metals subjected to welding processes. Experimental and numerical methods for determining residual stress are compared for welds generated using both TIG (Tungsten Inert Gas, Gas Tungsten Arc Welding) and a laser beam. This data reveals that it is necessary to precisely deﬁne location of the analyzed welded fragment to correctly determine thermal boundary conditions.

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A multi-criteria optimisation method for laser welding of austenitic steel 904L

Nasiłowska B., Pszczółkowski J., Bogdanowicz Z., Bożek M.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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Vol. 76, nr 2

72--84

EN

Purpose: Due to the increasing requirements for improvement of the welded structures quality, it is necessary to analyze the welding process in the design phase. In this context a system of criteria for optimization was introduced. This system is based on the integrated computational tools which allow specifying the function for the selection of the parameters of the welding process without the expensive experiments. Design/methodology/approach: The analysed independent variables were as follows: type of welding head (monofocal and bifocal), laser beam power (P) and laser beam travel (welding) speed (v). The following results were selected as the criteria of weld quality assessment: visual assessment of weld and root reinforcement, metallographic assessment of horizontal microsections, microhardness tests, shape factor determined using Jewdokimow and Lawrence methods, and the stress concentration factor. The weld cross-section shape factor was also used as a criterion. An objective function specifying the quality of weld was determined as the sum of point grades given for each of the above assessment criteria. Optimum values of the parameters for laser welding of 904L austenitic steel were determined using MatLab software while taking into account the values of the objective function,. After verifying the experimental results, the following parameters were identified for optimum laser welding of steel: laser beam power and speed of welding with a monofocal head. Findings: The range of the selected technological parameters, ie. head type, power and speed of the laser beam allowed to adjust optimal welding parameters based on the visual and destructive experiments, ie .: P = 4.5 kW, v = 1.4 m/min. Due to the lower defectiveness of the welded joints monofocal head was chosen. Research limitations/implications: This article presents the optimization procedure for the parameters of the laser welding of flat elements with a thickness of 5 mm made of steel 904L. Originality/value: This paper presents a procedure for configuring parameters for laser welding of steel using a multi-criteria optimization method for austenitic steel 904 L laser beam welding.

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Microstructure and mechanical behavior of a CO2 laser and TIG welded 904L steel

Bogdanowicz Z., Jóźwik P., Nasiłowska B.

Metallurgy and Foundry Engineering

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2014

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Vol. 40, no. 2

69--81

EN

This paper presents the analysis of structural research, micro-hardness and mechanical properties of the base material which is steel 904 L and joints made with CO2 laser beam and the TIG method. The analysis of the equilibrium system created in the Thermo-Calc programme based on chemical composition shows a dominancy of austenite with of Feα additions, phase σ, P and Laves’ and M23C6 and Cr9Mo21Ni20 carbides. EBSD (electron backscatter diffraction) research done by using an electron scanning microscope confirmed the presence of pure austenite.

PL

W pracy przedstawiono analizę badań strukturalnych, mikrotwardości i własności mechanicznych materiału rodzimego stali 904 L oraz połączeń wykonanych wiązką lasera CO2 i metodą TIG. Analiza układu równowagi utworzonego w programie Thermo-Calc na podstawie składu chemicznego wykazała dominujący udział austenitu z domieszkami Feα, faz σ, P i Lavesa oraz węglików M23C6 i Cr9Mo21Ni20. Badania EBSD (electron backscatter diffraction) wykonane przy użyciu elektronowego mikroskopu skaningowego potwierdziły obecność czystego austenitu.