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1

Review of Titanium Related Inclusions in Casting of Steel

Sheikh Ali R.

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 2

127--136

EN

The general area of understanding is inclusions in steel both metallic and nonmetallic in nature. This work has also used the concepts of inclusions in steel in general other than Ti however mainly the research works done on precipitation, solute segregation, grain developments and equilibrium aspects of important inclusions like Ti in steel have been probed. Interaction of inclusions with slag oxides has also been incorporated. Interdependence of elements common in-between many inclusions has been marked. TiN, TixOy and MnS inclusions have been very outstanding in the confines of present research. Ratios and effective concentration have been highlighted in certain cases around the topic. Type of steels, compositions of the constituent elements and temperature correlation has been spotted in certain environments. A suggestive relation with the steel properties has also been inferred. Hardness, corrosion behaviour and strength stand out to be the parameters of vital importance when considering Ti inclusions in the form of either TiN or TixOy. Certain inclusions like MnS seem to nucleate on TiN inclusions and there is a correlation evident certainly in case of complex alloys.

2

Stale konstrukcyjne typu maraging wytapiane próżniowo – zależność ciągliwości od zawartości wtrąceń niemetalicznych

Pawlak Stanisław Jerzy

Stal, Metale & Nowe Technologie

|

2022

|

nr 3-4

30--36

PL

W pracy analizowano ilościową zależność pomiędzy ciągliwością a zawartością wtrąceń niemetalicznych w odkuwkach o dużym przekroju z wytapianej próżniowo stali wysokostopowej typu maraging X2NiCoMo18-9-5. Wykonano badania własności wytrzymałościowych odkuwek i czystości metalurgicznej stali pochodzących z 17 wytopów przemysłowych. Obróbkę cieplną prowadzono według dwóch technologii różniących się sposobem austenityzowania, przy czym warunki starzenia były takie same, co prowadziło do uzyskania zbliżonych wartości wytrzymałości stali. Natomiast własności plastyczne stali przy ustalonej technologii produkcji były znacznie zróżnicowane, a główną przyczyną tego była czystość metalurgiczna stali.

EN

In the paper, the quantitative relationship between the ductility and volume fraction of the non-metallic inclusions in the vacuum melted X2NiCoMo18-9-5 maraging steel has been analysed. The tensile properties and cleanliness of steels from 17 industrial melts in the form of forged bars were determined. Two variants of the heat treatment in the austenitic range were used, followed by the same ageing conditions, which lead to the similar strength values of the steels. In contrary to that, significant variability in the tensile ductility was observed, which was attributed to the cleanliness of the steels.

3

Investigation of Particle Filtration in Aluminium Alloy

Baumann Benedict, Keßler A., Hoppach E., Wolf G., Szucki M., Hilger O.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 3

70--80

EN

The objective of this work is to gain a deeper understanding of the separation effects and particle movement during filtration of non-metallic inclusions in aluminum casting on a macroscopic level. To understand particle movement, complex simulations are performed using Flow 3D. One focus is the influence of the filter position in the casting system with regard to filtration efficiency. For this purpose, a real filter geometry is scanned with computed tomography (CT) and integrated into the simulation as an STL file. This allows the filtration processes of particles to be represented as realistically as possible. The models provide a look inside the casting system and the flow conditions before, in, and after the filter, which cannot be mapped in real casting tests. In the second part of this work, the casting models used in the simulation are replicated and cast in real casting trials. In order to gain further knowledge about filtration and particle movement, non-metallic particles are added to the melt and then separated by a filter. These particles are then detected in the filter by metallographic analysis. The numerical simulations of particle movement in an aluminum melt during filtration, give predictions in reasonable agreement with experimental measurements.

4

Influence of inclusions on bending fatigue strength coefficient the medium carbon steel melted in an electric furnace

Lipiński Tomasz, Wach Anna

Production Engineering Archives

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2020

|

Vol. 26, Iss. 3

88--91

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. Inclusions may also play an important role, subject to their type and shape. Inclusions may increase the strength of steel by inhibiting the development of micro-cracks. The analyzed material was one grade of medium-carbon structural steel. The study was performed on 6 heats produced in an industrial plant in 140 ton electric furnaces. The experimental variants were compared in view of the five heat treatment options. The results were presented to account for the correlations between the fatigue strength coefficient during rotary bending, the diameter of and spacing between impurities. The relationship between the fatigue strength and hardness of highgrade steel vs. the quotient of the diameter of impurities and the spacing between impurities was determined. The proposed equations contribute to the existing knowledge base of practices impact of impurities with various diameters and spacing between non-metallic inclusion on fatigue strength.

5

Diagnostyka pracy kadzi pośrednich stosowanych do odlewania wlewków płaskich i kwadratowych

Suchan Hanna, Baran Klaudia, Cwudziński Adam

Hutnik, Wiadomości Hutnicze

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2020

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Vol. 87, nr 1-2

17--21

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.

6

Badania filtracji ciekłej stali przez wielootworowe filtry ceramiczne w zależności od powierzchni kontaktu ciekła stal-filtr

Bogdał Agnieszka, Walaszczyk Klaudia, Felis Piotr, Superniak Adrian, Warzecha Marek

Hutnik, Wiadomości Hutnicze

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2020

|

Vol. 87, nr 9

221--224

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.

7

Efficiency of Aluminum Oxide Inclusions Removal from Liquid Steel as a Result of Collisions and Agglomeration on Ceramic Filters

Kalisz D., Kuglin K.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 2

43--48

EN

Filtration is one of the most efficient methods of removing Al2O3 inclusions from liquid steel. The efficiency of this process depends on the physicochemical parameters of liquid metal, inclusion and properties of the applied filters. The particles attracted during filtration undergo agglomeration, collisions and chemical reactions on the filter surface, with the emphasis on the mechanism of particle collisions and the role of material from which the filter was made. The aluminum oxide inclusions collide with the filter surface and as the growing process continues, the particles also collide with the previously adsorbed inclusions. At the interface of particle and filter the mixing of the metal bath is most intense, being a result of a sudden change of flow direction and breaking up the stream of liquid metal which is in a direct contact with material. The efficiency of filtration is defined not only by the behavior of individual particles but of all population. The simulations revealed that only a small fraction of these particles adheres directly to the filter material; most of them stick to the former ones. Attention should be also paid to the fact that some of the inclusions which contacted the filter walls do not form a permanent connection and are then entrained by metal. Authors solved the problem of agglomeration and collisions of Al2O3 inclusions with the ceramic surface of the filter with the PSG method, mainly used for the analysis of agglomeration of inclusions during steel refining in the ladle.

8

The Influence of Adsorbed Al2O3 Inclusions on the Viscosity Behavior of Mould Slag

Kalisz D., Kuglin K.

Archives of Foundry Engineering

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2019

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iss. 2

67--74

EN

The role of slag in the process of continuous casting of steel (CCS) is reduced to the thermal and chemical insulation of the liquid steel surface, and additionally to refining. The ability to adsorb non-metallic inclusions flowing off from the crystallizer, mainly Al2O3, determines its physicochemical properties. As a result of adsorption and dissolution of inclusions tin he liquid layer the viscosity and thickness of mould flux change, which eventually affects the technological parameters and behavior of slag in the crystallizer. The influence of aluminum oxide on the viscosity of slag was empirically investigated with a structural viscosity model worked out by Nakamoto. The results of the simulation are presented in the form of plots. Authors observed a significant influence of Al2O3 on the slag viscosity, which suggests that this effect should be taken into account when selecting chemical composition of mould flux for definite types of steel. The results of calculations also show that the disturbances in casting caused by the use of the mould slag may be connected with the content of non-metallic inclusions in steel.

9

The Effect of CaSiAl Modification on the Non-metallic Inclusions and Mechanical Properties of Low-carbon Microalloyed Cast Steel

Kalandyk B., Zapała R., Sobula S., Tęcza G.

Archives of Foundry Engineering

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2019

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iss. 1

47--52

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.

10

Bending fatigue strength coefficient the low carbon steel with impurities

Lipiński T.

Production Engineering Archives

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2018

|

Vol. 21

20--23

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.

11

Problem uszkodzenia iglic łukowych w rozjazdach zwyczajnych

Czarnecki M., Bińkowski R.

Problemy Kolejnictwa

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2018

|

Z. 180

7--14

PL

W artykule przedstawiono problem nadmiernego zużycia iglic łukowych w rozjazdach kolejowych zwyczajnych, charakteryzujący się wykruszeniem i ubytkiem materiału na pewnej długości w początkowym odcinku iglicy. Problem jest na tyle istotny, że zużycie pojawiło się w rozjazdach na zmodernizowanych liniach kolejowych już po kilkunastomiesięcznej eksploatacji. Na podstawie badań laboratoryjnych przeprowadzonych według norm PN-EN 13674-1:2011 i PN-EN 13674-2+A1:2010 oraz symulacji i analizy wykonanej metodą elementów skończonych (MES) wskazano prawdopodobne przyczyny nadmiernego zużycia iglic w rozjazdach kolejowych.

12

Problem of damage to curved switch rails in ordinary turnouts

Czarnecki M., Bińkowski R.

Problemy Kolejnictwa

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2018

|

Z. 180

79--86

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).

13

Laboratory studies on the development of composite pellets for deep refining of steel from non-metallic inclusions

Szypuła I., Zdonek B.

Prace Instytutu Metalurgii Żelaza

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2018

|

T. 70, nr 3

25--31

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.

14

Wpływ wylewu osłonowego kadzi stalowniczej i zmiany jego położenia na proces flotacji wtrąceń niemetalicznych z ciekłej stali w sześcio-wylewowej kadzi pośredniej

Bartosiewicz M., Cwudziński A.

Hutnik, Wiadomości Hutnicze

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2018

|

Vol. 85, nr 5

161--166

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.

15

Ocena wpływu warunków odlewania stalowego wlewka ciągłego na zachowanie się wtrąceń niemetalicznych – modelowanie numeryczne

Bielnicki M., Jowsa J.

Hutnik, Wiadomości Hutnicze

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2018

|

Vol. 85, nr 11

377--381

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.

16

Nonmetallic Inclusions in a New Alloy for Single-Crystal Permanent Magnets

Belyaev I. V., Bazhenov V. E., Kireev A. V., Moiseev A. V.

Archives of Foundry Engineering

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2018

|

Vol. 18, iss. 2

11--14

EN

The morphology, chemical composition and formation mechanism of non-metallic inclusions in magnetic alloy of Fe-Co-Ni-Cu-Al-Ti-Hf system were investigated. These alloys are used in manufacturing single-crystal permanent magnets. Modern methods for the identification of non-metallic inclusions, as well as computer simulation of the processes of their formation by Thermo Calc software were used in the work. It was found that studied alloy contains (Ti, Hf)S titanium and hafnium sulfides, (Ti, Hf)2SC titanium and hafnium carbosulfides, Ti2O2S titanium oxisulfide, HfO2 hafnium oxide, and Al2O3 aluminum oxide. No titanium and hafnium nitrides were found in the alloy. The bulk of nonmetallic inclusions are (Ti, Hf)2SC carbosulfides and (Ti, Hf)S sulfides. All carbides and many oxides are within carbosulfides and sulfides. When the sulfur content in the alloy is no more than 0.2%, and carbon content does not exceed 0.03%, carbosulfides are formed in the solidification range of the alloy and has an faceted compact form. If the sulfur content in the alloy becomes more than 0.2% and carbon content more than 0.03%, the carbosulfide formation begins before the alloy solidification or at the beginning stages of solidification. In this case, carbosulfides are dendritic and coarse. Such carbosulfides actively float in the solidified melt and often come to the surface of the castings. In this case, specific surface defects are formed in single-crystal magnets, which are called sulfide stains. All titanium and hafnium sulfides are formed at the lower part of solidification range and have elongated shape.

17

Ocena powtarzalności czystości metalurgicznej łuków ortodontycznych

Koczkodon K., Grygier D.

Aktualne Problemy Biomechaniki

|

2018

|

z. 15

13--20

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.

18

Numerical analysis of the effect of nonmetallic inclusionslocation in carburized layer of 16MNCR5 steel on initiation of fatigue cracking

Lipa Sebastian

Advances in Science and Technology. Research Journal

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2018

|

Vol. 12, no 3

66--74

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.

19

Wpływ energii mieszania na zjawisko aglomeracji cząstek wtrąceń niemetalicznych w ciekłej stali

Kuglin K., Kalisz D.

Prace Instytutu Odlewnictwa

|

2017

|

Vol. 57, no. 1

11--18

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.

20

The analysis of the water-expanded rock bolts ruptures during pressure test

Pawłowski B., Krawczyk J., Bała P., Cios G., Tokarski T.

Archives of Mining Sciences

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2017

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Vol. 62, no. 2

423--430

EN

This paper describe the investigation of a water-expanded rock bolts failed during pressure test (inner water pressure of 330 bar). A main objective of this work was to determine the cracks nucleation and propagation mechanism. It was found that the rock bolts failure was promoted by presence of non-metallic inclusions (mainly long sulphide inclusions) but the primary cause of cracking is strain ageing of steel. Suggestions for improving the behaviour of steel used for water-expanded rock belts by the modification of its chemical composition are proposed finally.

PL

W pracy opisano badania rozprężanych wodą kotw górniczych, które uległy pękaniu podczas prób ciśnieniowych (przy ciśnieniu wody wewnątrz kotwy 330 bar). Głównym celem badań było określenie mechanizmu zarodkowania i propagacji pęknięć. Stwierdzono, że propagacji pęknięć sprzyjała obecność wtrąceń niemetalicznych (głównie długich wydzieleń siarczków) ale podstawowym powodem występowania pęknięć jest zjawisko starzenia po zgniocie. W celu zminimalizowania występowania pęknięć, w pracy zaproponowano modyfikację składu chemicznego stali na tego rodzaju kotwy górnicze.