Wyniki wyszukiwania - BazTech

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Evaluation of chemical heterogeneity of a 90-ton forging ingot

Machovcak P., Opler A., Carbol Z., Trefil A., Merta K., Tkadleckova M., Michalek K.

Archives of Materials Science and Engineering

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2012

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Vol. 58, nr 1

22--27

EN

Purpose: This article describes performance of the experimental 90-ton forging ingot casting, the way of cutting, the methodology of chemical analysis and the results of that investigation. Design/methodology/approach: The experimental ingot 8K91SF weighing almost 90 tons was cast due the performance a detailed analysis of the current state of casting and solidification. The ingot was cut and macrostructure and chemical heterogeneity of the ingot was evaluated in detail. The standard method used in metallurgical analytics - analyses using optical emission spectrometers - was not applicable due to the large number of required analyzes. Thus, the mobile optical spectrometer SPECRTOTEST was used. Sulfur prints and fluid penetration tests were performed due to detect macroscopic distribution of sulfur and to locate surface-breaking defects. Findings: Current level of segregations of selected elements in real 90-ton steel ingot was detected. Also mutual mixing of two heats needed for the production of this ingot was verified. Research limitations/implications: Future research is focused on determination of inclusion content in selected parts of experimental ingot and on the level of micro-segregations. We are limited by the accuracy of chosen analytical method, which is also discussed in the paper. Practical implications: The gained knowledge is used to specification of the setting of boundary conditions of the numerical simulations, which should help to optimize the production technology of casting heavy forging ingots and minimize the level of segregation in ingots. Originality/value: New knowledge concerning mutual mixing of two heats needed for bottom casting of heavy forging ingot are presented in this paper. Distribution of segregation in so heavy ingot was detected. Results are the base for further investigations in macro-segregations and for the improving the accuracy of results of numerical simulations.

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Effect of heat treatment on chemical and microstructural heterogeneity of magnesium alloy AZ61

Horynova M., Dolezal P., Janova D., Gejdos P.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2010

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z. 97

51-52

EN

The contribution is focussed on the assessment of the influence of a heat treatment of magnesium alloy AZ61 on its chemical and microstructural heterogeneity. The experimental material was manufactured by squeeze casting method using alternative two-stage casting. The microstructure of the alloy in as cast state composed of ä solid solution, Mg17Al12 intermetallic phase and minor phases based on Mn. The heat treatment applied on the alloy was the solution annealing at the temperature of 380 °C and with graded dwell from 1 to 8 hours. Chemical etching was employed in order to estimate the micro-segregation of the elements in the matrix qualitatively and to discern the phases in the microstructure. The differences in matrix heterogeneity between the as cast state and after annealing were documented by means of light microscopy. Differences in etching between the central part and periphery of the crystalline units are apparent in the metallographic images. Quantitative assessment of chemical heterogeneity was done by mapping and local chemical microanalyses. It was found by mapping that with increasing delay at annealing temperature the Mg17Al12 intermetallic phase gradually dissolves and the micro-heterogeneity of each element decreases. Chemical heterogeneity of particular elements was measured by local chemical analysis and the intensity of chemical micro-heterogeneity of each sample was further expressed using effective distributive coefficients. It follows from the results that the solution treatment of the AZ61 magnesium alloy leads to diminishment of the chemical and microstructural heterogeneity. It also follows from the results presented that the combination of metallographic analyses with X-ray spectral analysis of wave- or energy-dispersive type is advantageous for the quantitative assessment of micro-segregation of elements in the matrix of magnesium alloys.

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Niejednorodność chemiczna domieszek metali nieżelaznych w stalach

Bazan J., Stransky K., Derda W.

Hutnik, Wiadomości Hutnicze

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2005

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Vol. 72, nr 12

574-578

PL

Przedmiotem niniejszego opracowania są wyniki mikroanalizy niejednorodności rozmieszczenia metali nieżelaznych wzdłuż granic ziaren w stali niskowęglowej. Metale te. podobnie jak fosfor i siarka, wiele stanowią niepożądane domieszki i negatywnie wpływają na wiele własności stali. Wyniki analizy chemicznej dla próbek w stanie lanym, stali wytopionej w warunkach laboratoryjnych, poddano obróbce statystycznej. Wyznaczono m.in. wartości współczynnika segregacji oraz tzw. efektywnego współczynnika podziału dla poszczególnych pierwiastków.

EN

The paper presents results of microanalysis of heterogeneity of non-ferrous metals distribution along the grain boundary in low carbon steel. These metals like phosphorus and sulphur are unwanted impurities which have a negative effect on steel properties. Results of chemical analysis for as cast samples of steelmaking under laboratory conditions were statistically treated. There were determined segregation indexes and calculated effective distribution coefficients for individual elements.

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Chemical heterogeneity of copolymers and its characterization

Kratochvil P., Stejskal J.

Polimery

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2001

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T. 46, nr 11-12

761-767

EN

The heterogeneity of copolymers in chemical composition is overviewed qualitatively. The following topics are discussed: the non-uniformity of copolymers and its description; the heterogeneity of statistical and block copolymers; tile effect of chemical heterogeneity on the properties of copolymers; the methods used to characterize chemically heterogeneous copolymers; size-exclusion chromatography (SEC) of copolymers involving concentration and composition detection; SEC with on-line concentration and light-scattering detection; and the calculation of the distribution functions of chemically heterogeneous copolymers based on the operating parameters of synthesis.

PL

Dokonano jakościowego przeglądu problemów dotyczących kopolimerów z punktu widzenia niejednorodności ich chemicznego składu. Omówiono następujące zagadnienia: niejednorodność kopolimerów i sposoby jej opisu; heterogeniczny charakter kopolimerów statystycznych oraz blokowych; wpływ heterogeniczności chemicznego składu na właściwości kopolimerów; metody charakteryzowania kopolimerów chemicznie heterogenicznych (ze szczególnym uwzględnieniem chromatografii ekskluzyjnej z detekcją stężeń i składu oraz chromatografii ekskluzyjnej z detekcją on-line stężenia i rozpraszania światła); obliczanie funkcji rozkładu kopolimerów chemicznie heterogenicznych pod względem ciężaru cząsteczkowego i składu na podstawie warunków ich syntezy.