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PL
W artykule przedstawiono wpływ pracy kadzi pośredniej na jakość odlewanych w sposób ciągły stalowych wlewków płaskich i kwadratowych. Przeprowadzenie badań na modelu wodnym pozwoliło uzyskać krzywe RTD typu F, na podstawie których określono strefę przejściową tworzącą się podczas odlewania sekwencyjnego dwóch różnych gatunków stali. Efektem wykonania symulacji numerycznych w programie Ansys-Fluent było określenie rozmieszczenia wtrąceń niemetalicznych w ciekłej stali oraz ocena poziomu rafinacji stali w trakcie procesu ciągłego odlewania.
EN
The article presents influence of tundish work on slabs and blooms quality during continuous steel casting. Water model investigations gave Residence Time Distributions curves type F, which allowed to define the transition zone between two different grades of steel during the sequential casting process. The Ansys-Fluent computer program was used for numerical simulation of non-metallic inclusions behaviour in the liquid steel and for estimation of inclusions removal level from liquid steel during casting.
PL
W pracy przedstawiono wyniki badań filtracji ciekłej stali przez wielootworowe filtry ceramiczne. Przedmiotem badań była stal wysokowęglowa z gatunku C70D. Proces przeprowadzono z zastosowaniem filtrów o różnej wysokości, a zarazem o różnej powierzchni filtracji, w układach filtru pojedynczego oraz podwójnego i potrójnego. Przeprowadzone badania miały na celu zbadanie procesu filtracji stali poprzez wyznaczenie ilości wtrąceń niemetalicznych i ich udziałów powierzchniowych przed i po procesie filtracji. Kolejnym etapem badań było określenie skuteczności filtracji względem ilości wtrąceń niemetalicznych i udziałów powierzchniowych.
EN
The paper presents the results of research on filtration process of high-carbon steel (grade C70D) through multi-hole ceramic filters. The process was carried out using filters with different highs - single filter, double and triple filter system. The research was aimed at determining the amount of nonmetallic inclusions and their surface shares before and after the filtration process. The next stage of the study was to determine the filtration efficiency relative to the amount of non-metallic inclusions and surface shares.
EN
In this work, the authors proposed a modification of the working space one-strand tundish adapted for slab casting process. Numerical simulations of liquid steel flow in the considered flow reactor were performed. The tundish is equipped with a dam with a multi-hole filter. Two variants of the filter hole arrangement were tested and their effect on the liquid steel flow hydrodynamic structure in the tundish was examined. The computer calculations results were verified by performing experiments on the water model. The result of numerical and physical simulations an RTD (Residence Time Distribution) type F curve was generated, which define the transition zone between the cast steel grades during the sequential casting process. The results of the researches showed that the modification of a dam with a multi-hole filter affects on the formation of the liquid steel flow hydrodynamic structure and the transition zone. Furthermore, examinations of the liquid steel refining ability in the considered tundish were carried out. The influence of the filter holes arrangement on the non-metallic inclusions flotation process to the slag phase and liquid steel filtration processes was checked. Numerical simulations were performed in the Ansys-Fluent computer program.
EN
The effect of CaSiAl modification (43-49% Ca, 43-48% Si, 2% Al) on the non-metallic inclusions and mechanical properties of cast low-carbon steel is discussed. Tests were carried out on the cast steel with 0.2% C and micro-additives of V and Nb, used mainly for heavy steel castings (e.g. slag ladles). The modifier in an amount of 1.5 and 3 kg / Mg was introduced to the liquid steel before tapping the metal into a ladle. Test ingots of Y type and a weight of 10 kg were cast and then subjected to a normalizing heat treatment. Using light microscopy and scanning electron microscopy, qualitative and quantitative evaluation of the non-metallic inclusions present in as-cast samples was carried out. Additionally, tests of mechanical strength and impact strength were performed on cast steel with and without the different content of modifier. It was found that increasing the modifier addition affected impact strength but had no significant effect on tensile strength and yield strength. The material with high impact strength had the smallest area fraction of non-metallic inclusions in the microstructure (0.20%). The introduction of modifiers changed the morphology of non-metallic inclusions from dendritic to regular and nodular shapes.
EN
The article discusses the results of a study investigating the effect of the number of fine non-metallic inclusions (up to 2 μm in size) on the fatigue strength of structural steel during rotary bending. The study was performed on 7 heats produced in an industrial plant. Fourteen heats were produced in a 100 ton oxygen converter. All heats were subjected to vacuum circulation degassing. Steel sections with a diameter of 18 mm were hardened and tempered at a temperature of 200, 300, 400, 500 and 600°C. The experimental variants were compared in view of the applied melting technology and heat treatment options. The heat treatments were selected to produce heats with different microstructure of steel, from hard microstructure of tempered martensite, through sorbitol to the ductile microstructure of spheroidite. The results were presented graphically, and the fatigue strength of steel with a varied share of non-metallic inclusions was determined during rotary bending. The results revealed that fatigue strength is determined by the relative volume of fine non-metallic inclusions and tempering temperature.
EN
The article presents the problem of excessive wear of curved switch rails in ordinary railway turnouts, which is characterized by spallings and the decrement of material on a certain length of the switch rail near the tip. The problem is important, as such wear arises in turnouts on railway lines after several months of exploitation following modernization. The probable reasons behind the excessive wear of switch rails in railway turnouts are indicated on the basis of laboratory tests performed in accordance with PN-EN 13674-1:2011 and PN-EN 13674-2+A1:2010, as well as on the basis of simulations and analyses carried out by the fi nite element method (FEM).
EN
The paper presents the laboratory research on the development of a new type of refining materials in the form of composite pellets for deep refining of steel from non-metallic inclusions, measured by the total oxygen content in steel below 10 ppm and the average size of non-metallic inclusions below 3 μm. The study included the development of a technology for pelletising materials selected for composite pellets, development of a technology for drying and hardening of pellets, making a batch of pellets and a series of laboratory heats using the produced pellets, assessment of the usefulness of composite pellets for industrial research, and development of assumptions for these tests.
PL
Przedstawiono badania laboratoryjne nad opracowaniem nowego rodzaju rafinacyjnych materiałów w postaci kompozytowych grudek do głębokiej rafinacji stali z wtrąceń niemetalicznych, mierzonej zawartością tlenu całkowitego w stali poniżej 10 ppm i średnią wielkością wtrąceń niemetalicznych, poniżej 3 µm. Opracowano technologię grudkowania materiałów dobranych na kompozytowe grudki, opracowano technologię suszenia i utwardzenia grudek, wykonano partię grudek oraz serię laboratoryjnych wytopów z wykorzystaniem wytworzonych grudek, dokonano oceny przydatności grudek kompozytowych do badań przemysłowych oraz opracowano założenia do tych badań.
PL
W artykule przedstawiono wyniki symulacji numerycznych przepływu ciekłej stali w sześcio-wylewowej kadzi pośredniej przeznaczonej do ciągłego odlewania wlewków kwadratowych. Zbadano wpływ zastosowania i zmiany głębokości zanurzenia w ciekłej stali wylewu osłonowego kadzi stalowniczej. Autorzy zaproponowali trzy warianty głębokości zanurzenia wylewu osłonowego. Bazowym wariantem badawczym była kadź pośrednia zasilana z kadzi stalowniczej niewyposażonej w wylew osłonowy. W ramach badań wykonano analizę struktury hydrodynamicznej przepływu ciekłej stali w strefie oddziaływania strumienia zasilającego. Ponadto, sprawdzono zdolność rafinacyjną wtrąceń niemetalicznych badanej kadzi pośredniej i wykonano analizę dystrybucji wtrąceń niemetalicznych pomiędzy poszczególnymi krystalizatorami. Wyniki obliczeń wykazały, iż zastosowanie i zmiana położenia wylewu osłonowego kadzi stalowniczej w procesie ciągłego odlewania stali wpływa na kierunki przepływu ciekłej stali w strefie oddziaływania strumienia zasilającego i na proces flotacji wtrąceń niemetalicznych do fazy żużla.
EN
The paper presents outcomes of the liquid steel flow numerical simulation in the six-strand tundish for continuous billet casting. Influence of use and change the ladle shroud immersion depth in liquid steel was examined. The authors proposed three cases of the ladle shroud immersion depths. The base research variant was tundish which was feeded by steel ladle without ladle shroud. The analysis of the liquid steel flow hydrodynamic structure was performed in the zone of main supplying stream influencing for all of the considered variants. Furthermore, ability of non-metallic inclusions refining in the considered tundish was checked and the analysis of the non-metallic inclusions distribution between the individual molds was performed. The calculation results showed that the use and location change of the ladle shroud in the continuous steel casting process affected the direction of liquid steel flow in the zone of the influence of main supplying stream and on the process of non-metallic inclusions floatation into slag.
PL
W pracy przedstawiono wyniki symulacji numerycznych zachowania się wtrąceń niemetalicznych w krystalizatorze. Analizowano wpływ: geometrii wylewu zanurzeniowego, prędkości odlewania, gęstości wtrąceń niemetalicznych oraz średnicy wtrąceń niemetalicznych na udział procentowy wtrąceń zasymilowanych przez żużel krystalizatorowy. Obliczenia wykonano w programie AnsysFluent®. Zaprezentowano przykładowe trajektorie ruchu wtrąceń niemetalicznych.Na podstawie wyników symulacji stwierdzono, że geometria wylewu zanurzeniowego wywiera najistotniejszy wpływ na liczbę wtrąceń niemetalicznych zasymilowanych przez żużel.
EN
In this paper the results of numerical simulations of behavior of non-metallic inclusion in mold are presented. The impact of: submerged entry nozzle geometry, casting speed, density of non-metallic inclusions and diameter of non-metallic inclusions on the percentage of inclusions assimilated by mold slag was analyzed. The calculations was carried out in Ansys Fluent® program. The examples of non-metallic inclusions trajectories are presented. Based on simulation results it was concluded, that submerged entry nozzle geometry exerts a most important influence on the number of non-metallic inclusions assimilated by the slag.
EN
The article discusses the effect of the diameter and spacing between impurities (size up to 2 μm) on the fatigue strength coefficient of structural steel during rotary bending. The study was performed on 21 heats produced in an industrial plant. Fourteen heats were produced in 140 ton electric furnaces, and 7 heats were performed in a 100 ton oxygen converter. All heats were desulfurized. Seven heats from electrical furnaces were refined with argon, and heats from the converter were subjected to vacuum circulation degassing. Steel sections with a diameter of 18 mm were hardened for 30 minutes from the austenitizing temperature of 880°C and tempered at a temperature of 200, 300, 400, 500 and 600°C. The experimental variants were compared in view of the applied melting technology and heat treatment options. The results were presented graphically and mathematically to account for the correlations between the fatigue strength coefficient during rotary bending, the diameter of and spacing between submicroscopic impurities. Equations for calculating the fatigue strength coefficient at each tempering temperature and a general equation for all tempering temperatures were proposed. Equations for estimating the fatigue strength coefficient based on the relative volume of submicroscopic non-metallic inclusions were also presented. The relationship between the fatigue strength and hardness of highgrade steel vs. the quotient of the diameter of impurities and the spacing between impurities, and the fatigue strength and hardness of steel vs. the relative volume of submicroscopic non-metallic impurities were determined.
EN
This paper presents the findings of fatigue strength tests of 15CrNi6 steel following low-pressure carburizing and oil quenching, subjected to cycles of one-sided three-point bending. The fatigue fractures were compared with the results of fatigue strength studies of 16MnCr5 steel following low-pressure carburizing and nitrogen quenching. The fatigue tests for 16MnCr5 steel were conducted as part of a high-cycle resonance test, with a pendular bending load. The study also involved an analysis of the effects on non-metallic inclusions in the structure on the mechanism of fatigue destruction. The inclusions were found to initiate fatigue cracks. In both cases, a similar method of a fatigue fissure initiation was observed, independent of the study method or specimen material.
PL
Materiały metaliczne przeznaczone do produkcji aparatów ortodontycznych powinny posiadać następujące cechy: wysokie właściwości mechaniczne i fizykochemiczne, biokompatybilność i jednorodność struktury. Bardzo ważnym aspektem jest również ich stopień zanieczyszczenia wtrąceniami niemetalicznymi. Wyniki badań prezentowanych w pracy wykazały dużą różnorodność w zakresie czystości metalurgicznej materiału badanych drutów, mogącej wskazywać, iż w analizowanej partii łuków znajdują się produkty pochodzące z różnych wytopów, znacząco różniące się jakością wykonania.
EN
The metallic materials designed to production of braces possess following features: high mechanical and physicochemical proprieties, biocompatibility and homogeneity of structure. Very important point is also degree non-metallic inclusion. The results of investigations presented in work show the large diverseness of metallurgical cleanness of studied wires material, which lead that various product could coming from different melting, non-uniform with quality of realization.
EN
This paper presents the results of a numerical analysis of the effect of the position of non-metallic inclusions in a hardened top layer in 16MnCr5 steel on the mechanism of fatigue destruction. An analysis of a hardened layer formed by thermo-chemical treatment using FineCarb® technology was conducted.Non-metallic inclusions formed by deoxidation of steel were studied; they are usually made of calcium and aluminum. Four positions of inclusions in the hardened layer were tested: under the layer, in the middle part of the layer, under the surface and on the border of two sublayers. The results of the FEM analysis were treated as a qualitative analysis. A map of plastic strains around the inclusion under study was observed. The appearance of plastic strains in the area under analysis signaledthe initiation of a fatigue crack. It was observed that the mechanism of destruction depends largely on the distribution of stress in the top layer and on the place where the inclusion is anchored in the layer. Inclusions under the layer were found to be the main cause of the loss of the structural continuity, which explains the most frequent cases of the initiation of fatigue cracks.
PL
W pracy wykonano obliczenia komputerowe, które polegały na rozwiązaniu równania bilansu populacji oraz równania częstotliwości zderzeń cząstek wtrąceń niemetalicznych w zależności od typu kolizji. W symulacjach wykorzystano metodę PSG (Particle Grouping Method). Badania zostały przeprowadzone dla określonej liczby cząstek tlenku glinu. Za wartości zmienne przyjęto promień cząstki oraz moc mieszania ε. Wyniki symulacji zaprezentowano w formie wykresów przedstawiających zmianę ilości wydzieleń w stosunku do ich liczby początkowej (n1/N0) dla pierwszej grupy rozmiarowej (n1) w funkcji czasu rzeczywistego, dla każdej rozpatrywanej początkowej wielkości promienia cząstki: 1, 5 i 10 μm. Analiza opracowanych wyników pozwoliła stwierdzić, że w przypadku cząstek charakteryzujących się większym promieniem wzrost energii mieszania intensyfikuje proces łączenia się wtrąceń niemetalicznych w aglomeraty, co w konsekwencji sprzyja procesom ich usuwania z objętości ciekłego metalu.
EN
In the research, computer calculations were performed, consisting in solving the equation of population balance and the equation of the collision frequency of non-metallic inclusion particles, depending on the type of collision. In the simulations, the PSG method (Particle Grouping Method) was applied. The studies were conducted for a specific number of aluminium oxide particles. The particle radius and the power of mixing ε were assumed as variables. The simulation results were presented in the form of diagrams showing the change of the number of precipitates in respect of their initial number (n1/N0) for the first group of sizes (n1) in real-time, for each analyzed initial size of the particle radius: 1, 5 and 10 μm. The analysis of the elaborated results made it possible to conclude that, in the case of particles characterized by a larger radius, the increased energy mix intensifies the process of inclusions joining in agglomerates, which, in consequence, favours the processes of their removal from the volume of the liquid metal.
EN
Deoxidation is an unavoidable step in the elaboration of steel. The study of its influence could improve the quality of low-carbon steel (0.20–0.25 wt.% of carbon). There are many deoxidation methods, and the most-common one consists of adding aluminum. Although it is a classic method, determining the optimal process parameters (quantity, yield, etc.) could be very sensitive. Deoxidation plays a determining role on inclusion cleanliness, especially on sulfide morphology. In order to control the efficiency of deoxidation, different techniques can be used. In this paper, an automated counting procedure on a scanning electron microscope with a field emission gun (FEG-SEM) is presented. This method was applied on samples cast in our laboratory under different deoxidation conditions. According to this, the resulting inclusion population is correlated with the aluminum content to find the optimal process parameters.
EN
This paper presents the results of calculating the phenomenon of the absorption of non-metallic precipitates in steel by slag. Calculations are made for the forces acting on the non-metallic particles in steel during the flow-out into the slag, depending on the particle radius and physicochemical properties of the liquid steel and slag. An analysis of the calculation results of capillary force acting on a particle in the vicinity of the steel-slag interface at changing surface energy values between the precipitates and slag shows that capillary force depends on the interfacial tension between the precipitates and slag only to a small degree.
EN
The Electro Slag Remelting (ESR) is one of the remelting processes in the field of metal refinery. In this process, the slag plays various roles, such as heat generation, protection of melt, and chemical refining. The main objective of the experiments described in this article was to identify the most appropriate slag composition for the electro slag remelting of the steel in order to achieve the chemical composition compliant with the standard applicable to the given steel, minimum sulphur content, minimum contents of oxide and sulphide inclusions, as well as mechanical properties corresponding to the standard applicable to the steel STN 14 109. Ten electrodes were remelted, whereas the remelting was carried out under 8 slags. The used slags containing 70% of CaF2 and 30% of Al2O3 with different addition of CaO, the slags consisted of the same components as previous slags, whereas the ratio of individual components was 1:1:1, and with SiO2 and MgO and slag without Al2O3. With regard to all the above mentioned facts, the slag types which may be regarded as the most appropriate for the STN 14 109 steel remelting are the basic slags containing 70% of CaF2 - 30% of Al2O3 with added 30 and 45 weight % of CaO.
EN
The parameters of high-grade steel are influenced by a combination of factors, including chemical composition and production technology. The impurity content is also a key determinant of the quality of high-grade steel. Non-metallic inclusions are one of the factors that influence the properties in particular fatigue strength of steel. The experimental material consisted of semi-finished products of medium-carbon structural steel. The production process involved three melting technologies: steel melting in a basic arc furnace with desulfurization or desulfurization and argon refining and in a oxygen converter and the next subjected to vacuum circulation degassing. This paper discusses the results of microstructural analyses, the changes in bending fatigue strength of steel hardened and tempered at different temperatures subjected to the size proportions and distances between the impurities of structural steel.
PL
W artykule przedstawiono wyniki badań wpływu udziału złomu obiegowego we wsadzie stopu AZ91 na zmianę struktury odlewów wykonanych metodą wysokociśnieniowego odlewania, ze szczególnym uwzględnieniem tworzenia się wtrąceń niemetalicznych. Na podstawie obserwacji wtrąceń metodą mikroskopii skaningowej określono skład chemiczny tych wtrąceń w wytopach z różnym udziałem złomu obiegowego we wsadzie.
EN
The article presents research results of the process foundry return influence in the AZ91 alloy charge on the change in the structure of castings made by the high-pressure casting method, with special consideration of the formation of non-metallic inclusions. Based on the observations of inclusions by the scanning microscopy method, the chemical composition of the inclusions in melts with different process scrap contents in the charge was determined.
PL
W artykule przedstawiono wyniki badań wpływu warunków wytapiania i odlewania eksperymentalnych stali zawierających 3÷5% glinu na rodzaj i morfologię wtrąceń niemetalicznych. Wytopy badawcze wykonano w elektrycznym piecu indukcyjnym z zastosowaniem próżni oraz w atmosferze powietrza. Przeprowadzono analizę ilościową i jakościową wtrąceń niemetalicznych po przeróbce plastycznej na gorąco. W stalach wytapianych i odlewanych w powietrzu występują głównie wtrącenia AlN, MnS, Al2O3 oraz złożone wtrącenia tlenkowo-siarczkowe. Udział objętościowy wszystkich wtrąceń niemetalicznych stanowi 0,10÷0,12% obj. i jest większy o ok. 30% w porównaniu ze stalą wytapianą w próżni.
EN
The paper presents the effect of melting and casting conditions of experimental steels with 3÷5% of aluminium on the type and morphology of non-metallic inclusions. The experimental heats were carried out in an electric induction furnace in vacuum and in air atmosphere. A quantitative and qualitative analysis of non-metallic inclusions was conducted after hot plastic working. Steels which were melted and casted in air atmosphere contain mainly AlN, MnS, Al2O3 and complex oxide-sulfide inclusions. The volume fraction of non-metallic inclusions was 0.10÷0.12% and it was about 30% higher than the volume of inclusions in the steel produced in vacuum.
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