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1
Content available Characteristics of Ledeburite in EDS Analyses of Directionally Solidified Eutectic White Cast Iron
Trepczyńska-Łent Małgorzata, Seyda J.
Archives of Foundry Engineering
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2022
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Vol. 22, iss. 4
65--71
EN
The paper addresses the microsegregation of Mn, Mo, Cr, W, V, Si, Al, Cu and P in the white cast iron. Eutectic alloy with the content of 4.25% C was studied. The white cast iron was directionally solidified in the vacuum Bridgman-type furnace at a constant pulling rate v=83 μm/s and v=167 μm/s and at a constant temperature gradient G = 33.5 K/mm. The microstructural research was conducted using light and scanning electron microscopy. The microsegregation of elements in ledeburite was evaluated by EDS measurements. Content of elements in ledeburitic cementite and ledeburitic pearlite was determined. The tendency of elements to microsegregation was found dependent on the solidification rate. Microsegregation of elements between pearlite and cementite structural constituents has been specified. The effect of solidification rate on the type and intensity of microsegregation in directionally solidified eutectic white cast iron was observed. A different type of microsegregation was observed in the components of ledeburite in cementite and pearlite.
2
Content available Solidification Front of Oriented Ledeburite
Trepczyńska-Łent M., Olejnik E.
Archives of Foundry Engineering
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2016
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Vol. 16, iss. 1
124--130
EN
Directional solidification of the Fe - 4,3 wt % C alloy was performed with the pulling rate equal to v=83 μm/s. Sample was frozen during solidification to reveal the shape of the solid/liquid interface. Structures eutectic pyramid and spherolitic eutectic were observed. The solidification front of ledeburite eutectic was revealed. The leading phase was identified and defined.
3
Content available X-ray Diffraction Study of Directional Solidification Ledeburite
Trepczyńska-Łent M., Szykowny T.
Archives of Foundry Engineering
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2015
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Vol. 15, iss. 3
71--76
EN
Directionally solidified sample of Fe-Fe3C eutectic alloy were produced under an argon atmosphere in a vacuum Bridgman-type furnace to study the eutectic growth with v = 167 μm/s pulling rate and constant temperature gradient G = 33.5 K/mm. Since how the growth texture of eutectic cementite is related to its growth morphology remains unclear, the current study aims to examine this relationship. The technique such as X-ray diffraction, have been used for the crystallographic analysis of carbide particles in white cast irons.
4
Content available Directional solidification of ledeburite
Trepczyńska-Łent M.
Archives of Foundry Engineering
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2013
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Vol. 13, iss. 3
101--106
EN
Directional solidification of ledeburite was realised out using a Bridgman’s device. The growth rate for movement sample v=83.3 μm/s was used. In one sample the solidification front was freezing. The value of temperature gradient in liquid at the solidification front was determined. Interfacial distance λ on the samples was measured with NIS-Elements application for image analysis.
5
Content available Solidification of Ledeburite Eutectic
Trepczyńska-Łent M.
Archives of Foundry Engineering
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2012
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Vol. 12, iss. 2s
71--74
EN
The ledeburite eutectic is one from the most commercial eutectics of group the quasi-regular eutectics. The paper presents the knowledge of growth this eutectic. In the case high solidification, the foundation near which formulate the right growth eutectic they are fulfilled.
6
Content available remote The influence of microstructure on the mechanical properties of metallurgical rolls made of G200CrMoNi4-3-3 cast steel
Brodziak A., Stradomski Z., Pirek A.
Archives of Foundry Engineering
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2009
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Vol. 9, iss. 3
21-24
EN
The subject of the study is the high-carbon tool cast steel G200CrMoNi4-3-3 used for metallurgical rolls, especially in section rolling mills. The test material was derived from a roll damaged in production; therefore, the authors had the material in a raw state at their disposal, on which they were able to carry out additional heat treatment operations. The pearlitic matrix of casting steel G200CrMoNi4-3-3 allows machining to be done to modify the pass or to remove any defects, and the primary and secondary precipitates of carbides enhance the tribological properties. The authors have been for years involved in the optimization of the structure of this material by slight correction to its chemical composition and/or the modification of heat treatment. The presented principles of heat treatment modifications will lead to considerable economic and ecologic profits. It has also been demonstrated that raising slightly the contents of carbide-forming elements, which markedly increases the quantity of transformed ledeburite, results in an enhancement of tribological properties. The analysis of a dozen or so rolls exploited down to the dead roll diameter has shown that roll of cast steel with increased contents of carbon and carbide-forming elements exhibit better service properties, as characterized by the amount of feedstock rolled. Such a method of enhancing the service properties required the assessment of fracture toughness, which was verified using the linear-elastic methods of fracture mechanics.
7
Content available remote Structural causes of defects in a cast iron mill roll
Krawczyk J.
Archives of Foundry Engineering
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2008
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Vol. 8, iss. 2
93-98
EN
This paper describes an analysis of a defective microstructure of a mill roll. For this purpose, a piece of a broken roll was collected. That roll was made of mottled cast iron. Its microstructure consisted of modular graphite, transformed ledeburite and a matrix composed of bainite and martensite. Metallographic investigations were performed nearby the fracture in the roll. Observations were conducted on polished sections, first not etched, and then etched, which allowed us to trace carefully the propagation of the fracture. There was found a strict correlation between the microstructure of the roll and the progress occurring in the crack. It was ascertained that the basic reason for the damage to the roll was banded precipitations of ledeburitic cementite. In addition, cementite formed a continuous network. Another microstructure defects of that roll are also precipitations of secondary carbides on the boundaries of former grain of austenite as well as the occurrence of upper bainite in its matrix. The results obtained hereunder allow broadening the data base relative to the genesis of damages to mill rolls, which in future will permit one to design a proper microstructure of cast iron mill rolls. Proper microstructure of cast iron mill roll should be shaped at the stage of designing the chemical composition, conditions of crystallization or heat treatment if any.
8
Content available The role of metallurgical defects and microstructure on failure formation in roll necks of cast iron rolls
Krawczyk J., Pacyna J.
Metallurgy and Foundry Engineering
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2007
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Vol. 33, no. 2
89-96
EN
This work presents the examples of structural reasons for failure of the necks of cast iron rolls. The most common reason for damage of metallurgical roll necks is a presence of shrinkage porosity in their volume. Moreover, a high fraction of ledeburitic cementite can lead to the formation of a continuous net of eutectic carbides, which facilitate cracking. Even very thin net of secondary carbides, formed on the boundaries of former grain of austenite, can significantly facilitate propagation of the crack. Continuous net of ledeburitic cementite, in the case of its precipitation in a form of bands and existence of hardened areas in the alloy matrix can lead to roll neck fracture relatively easy. The use of flake graphite cast iron for metallurgical rolls increases a risk of the fracture of roll neck.
PL
W niniejszej pracy przedstawiono przykłady strukturalnych przyczyn uszkodzeń czopów w żeliwnych walcach hutniczych. Najczęstszą przyczyną uszkodzeń czopów walców hutniczych jest zaleganie w nich obszarów rzadzizn. Ponadto duży udział cementytu ledeburytycznego może prowadzić do powstania ciągłej siatki węglików eutektycznych, która tworzy drogę łatwego pękania. Nawet bardzo cienka siatka węglików drugorzędowych utworzona na granicach pierwotnego ziarna austenitu może w znaczący sposób ułatwiać rozwój pęknięcia. Ciągła siatka cementytu ledeburytycznego, w przypadku jego wydzielania w postaci pasmowej oraz występowanie w osnowie obszarów podhartowanych, może doprowadzić do łatwego złamania czopa walca. Zastosowanie na walce hutnicze żeliwa z grafitem płatkowym zwiększa niebezpieczeństwo złamania czopa.
9
Content available remote Właściwości żeliwa szarego nadtopionego wiązką laserową
Adamiak S.
Archiwum Odlewnictwa
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2006
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R. 6, nr 18/2
189--194
PL
W pracy przedstawiono wyniki badań dotyczące wpływu obróbki laserowej na strukturę i mikrotwardość niestopowego żeliwa szarego. Przedstawiono procesy zachodzące podczas krystalizacji żeliwa po laserowym przetopieniu oraz ich wpływ na strukturę warstwy wierzchniej. Uzyskano znaczny wzrost mikrotwardości w warstwie nadtopionej jak i strefie wpływu ciepła.
EN
This work present results microstructure and properties of grey cast iron after laser treatment examined. Introduced process crystallization of grey cast iron after laser remelting. Remelting zone of gray cast iron consist of cells and dendritic cells. Received increase microhardness of consolidation area by laser.
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