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Abstract

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.
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Bibliography

[1] Podrzucki, Cz. (1991). Cast iron. Structure. Properties. Application T.1 and T.2, First Edition, Publishing house ZG STOP. (in Polish)
[2] Sękowski, K. (1973). Heterogeneity of the chemical composition of the metal matrix of ductile iron. Foundry Review. 8-9, 205-255413. (in Polish)
[3] Pietrowski, S. (1987). The influence of the chemical composition of nodular cast steel and cast iron and casting cooling rate on the austenite transformation to acicular structures. Scientific Books nr 94: Technical University of Łódź. (in Polish)
[4] Pietrowski, S. & Gumienny, G. (2006). Crystallization of nodular cast iron with additions of Mo, Cr, Cu and Ni. Archives of Foundry. 6(22), 406-413. (in Polish)
[5] Pietrowski, S. & Gumienny, G. (2012). Microsegregation in nodular cast iron with carbides. Archives of Foundry Engineering. 12(4), 127-134. DOI: 10.2478/v10266-012-0120-z.
[6] Sandoz, G. (1968). Recent Research in Cast Iron, H. Marchant, ed. New York: Gordon and Breach, 509.
[7] Malinochka, Ya.N., Maslenkov, S.B. & Egorshina, T.V. (1963). Investigation of microsegregation in cast iron using electron microprobe. Liteinoe Proizvodstvo, 1, 22-25. (in Russ.)
[8] Swindelsand, N. & Burke, J. (1971). Silicon microsegregation and first stag graphitization in white cast irons. Metallurgical Transactions. 2, 3257-3263. DOI: 10.1007/BF02811605
[9] Charbonnier, J. & Margerie, J.C. (1967). Nouvelle contribution al’etude generale des mikrosegregation dans les alliages Fe-C du type ”fonte”. Fonderie. 259, 333-344.
[10] Bazhenov, V.E., & Pikunov, M.V. (2018) Microsegregation of silicon in cast iron. Izvestiya. Ferrous Metallurgy. 61(3), 230-236. DOI: 10.17073/0368-0797-2018-3-230-236 (in Russ.)
[11] Park, J.Y. and other (2002). Effect of Mn negative segregation through the thickness direction on graphitization characteristics of strip-cast white cast iron. Scripta Materialia 46(3), 199-203. https://doi.org/10.1016/S1359-6462(01)01220-9
[12] Dojka, M. & Stawarz, M. (2020). Bifilm defects on Ti-inculated chromium white cast iron. Materials. 13(14), 3124. https://doi.org/10.3390/ma13143124
[13] Trepczyńska-Łent, M. (1997). Spheroidizing annealing of whitened ductile iron. 1st National Scientific Conference "Materials Science - Foundry - Quality", 129-137, Krakow. (in Polish)
[14] Trepczyńska-Łent, M. (1998). Microsegregation of silicon and manganese after spheroidizing annealing in cast iron with spherical graphite. Scientific Journals ATR 216, Mechanics. 43, 217-226. Bydgoszcz (in Polish).
[15] Chang, W.S. & Lin, C.M. (2013). Relationship between cooling rate and microsegregation in bottom-chilled directionally solidified ductile irons. Journal of Mining and Metallurgy, Section B: Metallurgy. 49(3)B, 315-322. https://doi.org/10.2298/JMMB120702034C.
[16] Trepczyńska-Łent, M. Boroński D. & Maćkowiak P. (2021). Mechanical properties and microstructure of directionally solidified Fe-4.25%C eutectic alloy. Materials Science and Engineering A, 822(3) 141644. https://doi.org/10.1016/j.msea.2021.141644.
[17] Trepczyńska-Łent, M. (2017). Interphase spacing in directional solidification of white carbide eutectic, METAL 2017 - 26th International Conference on Metallurgy and Materials, Conference Paper, Conference Proceedings Volume 2017-January 254-260. ISBN: 978-808729479-6.
[18] Trepczyńska-Łent, M. (2017). Directional solidification of Fe-Fe3C white eutectic alloy. Crystal Research and Technology 52(7) July 2017, 1600359, version of record online: 26 JUN 2017. DOI: 10.1002/crat.201600359.
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Authors and Affiliations

M. Trepczyńska-Łent
1
ORCID: ORCID
J. Seyda
1
ORCID: ORCID

  1. Bydgoszcz University of Science and Technology, Poland
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Abstract

The paper addresses the macro- and microsegregation of alloying elements in the new-developed Mn-Al TRIP steels, which belong to the third generation of advanced high-strength steels (AHSS) used in the automotive industry. The segregation behaviour both in the as-cast state and after hot forging was assessed in the macro scale by OES and by EDS measurements in different structural constituents. The structural investigations were carried out using light and scanning electron microscopy. A special attention was paid to the effect of Nb microaddition on the structure and the segregation of alloying elements. The tendency of Mn and Al to macrosegregation was found. It is difficult to remove in Nb-free steels. Microsegregation of Mn and Al between austenite and ferritic structural constituents can be removed.

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Authors and Affiliations

A. Grajcar
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Abstract

The (Zn) – single crystal strengthened by the E = (Zn) + Zn16Ti eutectic precipitate is subjected to directional growth by the Bridgman’s system and current analysis. Experimentally, the strengthening layers (stripes) are generated periodically in the (Zn) – single crystal as a result of the cyclical course of precipitation which accompanies the directional solidification. These layers evince diversified eutectic morphologies like irregular rods, regular lamellae, and regular rods. The L – shape rods of the Zn16Ti – intermetallic compound appear within the first range of the growth rates when the irregular eutectic structure is formed. Next, the branched rods transform into regular rods and subsequently the regular rods into regular lamellae transitions can be recorded. The regular lamellae exist only within a certain range of growth rates. Finally, the regular rods re-appear at some elevated growth rates.

A new solution to the diffusion equation is provided to describe the micro-field of the solute concentration in the liquid adjacent to the front of the growing eutectic structure. The solution is based on the mass balance in the considered system. Moreover, the existence of the protrusion of the leading eutectic phase over the wetting one is required by the mass balance. The appearance of the d – protrusion in the growing eutectic is well confirmed by the experimental observations of the frozen solid/liquid interface. The mentioned solution satisfies the concept of the eutectic coupled growth according to which undercooling of the leading phase is less than undercooling of the wetting eutectic phase. Also, the Ti – solute micro-segregation / redistribution is analyzed within the matrix of the single crystal. The micro-segregation is described as a result of the solution to the adequate, newly developed differential equation. The definition for the solute redistribution is given by the subsequently / separately formulated relationship. This definition takes into account both extent -, and intensity of the solute redistribution.

Finally, the entropy production is calculated for the regular lamellae -, and for the regular rods formation, respectively. The entropy production is a function of some parameters which define the eutectic phase diagram, coefficient of the diffusion in the liquid, and some capillary parameters connected with the mechanical equilibrium located at the triple point of the solid/liquid interface. Branches formation is related to the marginal stability. A new criterion is formulated and subjected to successful verification. It is: in the structural – thermodynamic competition the winner is this kind of the pattern for which minimum entropy production has a lower value.

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Authors and Affiliations

W. Wołczyński
ORCID: ORCID
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Abstract

The main work of this paper focuses on the simulation of binary alloy solidification using the phase field model and adaptive octree grids.

Ni-Cu binary alloy is used as an example in this paper to do research on the numerical simulation of isothermal solidification of binary

alloy. Firstly, the WBM model, numerical issues and adaptive octree grids have been explained. Secondary, the numerical simulation

results of three dimensional morphology of the equiaxed grain and concentration variations are given, taking the efficiency advantage of

the adaptive octree grids. The microsegregation of binary alloy has been analysed emphatically. Then, numerical simulation results of the

influence of thermo-physical parameters on the growth of the equiaxed grain are also given. At last, a simulation experiment of large scale

and long-time has been carried out. It is found that increases of initial temperature and initial concentration will make grain grow along

certain directions and adaptive octree grids can effectively be used in simulations of microstructure.

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Authors and Affiliations

Y. Yin
Y. Li
K. Wu
J. Zhou
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Abstract

In this paper results of microsegregation in the newly developed nodular cast iron with carbides are presented. To investigate the pearlitic and bainitic cast iron with carbides obtained by Inmold method were chosen. The distribution of linear elements on the eutectic cell radius was examined. To investigate the microsegregation pearlitic and bainitic cast iron with carbides obtained by Inmold method were chosen. The linear distribution of elements on the eutectic cell radius was examined. Testing of the chemical composition of cast iron metal matrix components, including carbides were carried out. The change of graphitizing and anti-graphitizing element concentrations within eutectic cell was determined. It was found, that in cast iron containing Mo carbides crystallizing after austenite + graphite eutectic are Si enriched.

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Authors and Affiliations

S. Pietrowski
G. Gumienny

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