Wyniki wyszukiwania - Biblioteka Nauki

1

Solubility of nitrogen in liquid Fe-10Ti and Fe-25Ti alloys

100%

Hutny A. , Siwka J.

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2012

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tom Vol. 55, nr 2

265--269

EN

Purpose: of the study was to determine the physicochemical characteristics of thermodynamic equilibrium in the liquid metal-gas system, where the liquid metal was a liquid Fe-Ti alloy, and the reaction gas was always a mixture of nitrogen and argon with preset chemical composition. Design/methodology/approach: In the experimental studies, the levitation metal melting technique was used, which enabled, on the one hand, the liquid metal-gas thermodynamic system appropriate to the purpose to be fabricated and, on the other hand, precise measurements to be carried out within a wide nitrogen partial pressure range from 0.0005 to 0.070 atm and in the appropriate range of metal temperature variations (1973-2273 K). The solidification of a 1 g-mass sample at a rate higher than 1000 K/s assured the complete nitrogen fixation in the solidified sample compared to the liquid-state sample. Findings: It has been established in the study by experimentally measuring the nitrogen concentration in the liquid Fe-Ti alloy with varying titanium contents under hyperbaric conditions that the solubility of nitrogen in liquid Fe-Ti alloys increases with increasing partial pressure of nitrogen in the gaseous phase, and with increasing liquid metal temperature and titanium content of the metal. Research limitations/implications: The study has found that when the intensive parameters increase above the critical values, the non-metallic phase forming on the levitating metal drop surface is a titanium nitride film, as demonstrated by X-ray analysis. Such samples were eliminated from the characteristics of nitrogen solubility in the homogeneous metallic phase. Practical implications: The collected data on the thermodynamic quantities of the liquid Fe-Ti-N alloy has enriched the autonomous thermodynamic database containing information about liquid alloys of iron with nitrogen, which is being built at Czestochowa University of Technology. Originality/value: The developed formulas seem to be valuable, because - as the relevant literature indicates -the Fe-Ti system has not been examined so far under such extreme thermodynamic conditions.

2

Investigation of nitrogen solubility in liquid Fe-V alloys with the use of levitation technique

100%

Hutny A. , Siwka J.

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tom Vol. 46, iss. 2

197-206

EN

A methodology and the results of experimental studies on nitrogen solubility in liquid Fe-V alloys are presented in the article. The investigations were carried out using the levitation metal melting technique. Liquid Fe-V alloys (%V - 1.5; 5.8: 7.8; 12.2) were saturated with nitrogen at the temperature 2173 K. Nitrogen partial pressure was varied within the range of 0.1-2.1MPa. The experiment involved melting down a 1 g-mass sample in an electromagnetic field produced by a levitation coil, filling the reaction chamber with nitrogen up to the required pressure, and heating the sample up to the preset temperature. The sample was held in this condition for 180 s. Then, the power supply of the coil was switched off and a metal drop fell by gravity into a small copper mould in which the metal solidified in the conditions of rapid crystallisation. Nitrogen contents were determined by the method of extraction to a neutral gas using a Leco TC-336 apparatus. High nitrogen concentrations were obtained in metal samples as the result of high nitrogen partial pressures in the gaseous phase within the reaction chamber. In these conditions, all interactions of nitrogen in the alloy examined could be revealed, namely: nitrogen-vanadium, nitrogen-nitrogen, and nitrogen-nitrogen-vanadium interactions. In the case of the liquid Fe-V alloy, a solid phase of vanadium nitride separates from the liquid after exceeding the nitrogen solubility limit. The tests were carried out within such a range of nitrogen concentrations where a given Fe-V alloy was still homogeneous. Investigation results have shown a nonlinear dependence of the activity coefficient, fN, not only on the vanadium content of alloy, but on its nitrogen content as well. Therefore, interaction between nitrogen atoms in liquid Fe-N-V alloys has been documented.

PL

W pracy przedstawiono metodykę oraz wyniki badań eksperymentalnych nad rozpuszczalnością azotu w ciekłych stopach Fe-V. Badania przeprowadzone zostały przy użyciu techniki lewitacyjnego topienia metali. Ciekłe stopy Fe-V (%V - 1.5: 5,8; 7,8; 12,2) nasycano azotem przy temperaturze 2173 K. Ciśnienie cząstkowe azotu zmieniano w zakresie 0,l-2.1MPa. Eksperyment polegał na roztopieniu próbki o masie 1 g w polu elektromagnetycznym wytworzonym przez cewkę lewitacyjną, napełnieniu komory reakcyjnej azotem do wymaganego ciśnienia i nagrzaniu próbki do zadanej temperatury. W takim stanie próbkę wytrzymywano przez 180 s. Następnie wyłączono zasilanie cewki i kropla metalu spadała grawitacyjnie do miedzianej wlewniczki, w której metal krzepł w warunkach szybkiej krystalizacji. Zawartości azotu określane były metodą ekstrakcji do gazu obojętnego przy użyciu aparatu Leco TC-336. W próbkach metalu uzyskiwano wysokie stężenia azotu, na skutek wytwarzania wysokich ciśnień cząstkowych azotu w fazie gazowej przestrzeni reakcyjnej. W takich warunkach mogły być ujawnione wszystkie oddziaływania azotu w badanym stopie a mianowicie: oddziaływania azot-wanad, azot-azot, azot-azot-wanad. W przypadku ciekłego stopu Fe-V, po przekroczeniu granicy rozpuszczalności azotu, wydziela się z cieczy stała faza azotku wanadu. Badania prowadzono w takim zakresie stężeń azotu, przy którym dany stop Fe-V był jeszcze homogeniczny. Wyniki badań wykazały nieliniową zależność współczynnika aktywności fN nie tylko od zawartości wanadu w stopie ale również od zawartości w nim azotu. Zatem udokumentowano oddziaływanie pomiędzy atomami azotu w ciekłych roztworach Fe-N-V.

3

Mathematical and Physical Modeling of Alloy Behavior Feeding by Pulse-Step Method to Liquid Steel in One Strand Slab Tundish

80%

Cwudziński A. , Gajda B. , Hutny A. , Jowsa J.

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4

Investigations of Dual Plug Argon Blowing for Efficient Mixing at Ladle Furnace Station

71%

Warzecha M. , Hutny A. , Warzecha P. , Kutyła Z. , Merder T. , Warzecha M. , Hutny A. , Warzecha P. , Kutyła Z. , Merder T.

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5

Investigations of Dual Plug Argon Blowing for Efficient Mixing at Ladle Furnace Station

70%

Warzecha M. , Hutny A. , Warzecha P. , Kutyła Z. , Merder T.

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tom Vol. 66, iss. 2

561--572

EN

The article presents the results of model research concerning the change of technology of argon blowing into liquid steel at the ladle furnace, using the dual plug system. The results of numerical simulations were verified with experimental data carried out on the water model device. The verified model was used to perform numerical simulations to predict the impact of using a new gas injection technology - with different flow rates - on the time to achieve the assumed degree of metal chemical homogenization after alloy addition. Simulation results show that argon blowing metal bath in dual plug mode can effectively reduce mixing time compared to conventional technology with the same gas flow rates. Generally, the use of the dual plug system is beneficial for reducing the bath mixing time, however, the assumed optimal proportion of gas blown through individual plug should be followed. Finally, numerical predictions were used to perform experimental melt under industrial conditions. Industrial verification has clearly confirmed the validity of numerical modeling and showed that also in industrial conditions, a shorter time of chemical homogenization was obtained for the dual plug system.