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1

Role of the Structural and Thermal Peclet Numbers in the Brass Continuous Casting

Kwapisiński P., Lipnicki Z., Ivanova A. A., Wołczyński W.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

49--54

EN

The Structural Peclet Number has been estimated experimentally by analyzing the morphology of the continuously cast brass ingots. It allowed to adapt a proper development of the Ivantsov’s series in order to formulate the Growth Law for the columnar structure formation in the brass ingots solidified in stationary condition. Simultaneously, the Thermal Peclet Number together with the Biot, Stefan, and Fourier Numbers is used in the model describing the heat transfer connected with the so-called contact layer (air gap between an ingot and crystallizer). It lead to define the shape and position of the s/l interface in the brass ingot subjected to the vertical continuous displacement within the crystallizer (in gravity). Particularly, a comparison of the shape of the simulated s/l interface at the axis of the continuously cast brass ingot with the real shape revealed at the ingot axis is delivered. Structural zones in the continuously cast brass ingot are revealed: FC – fine columnar grains, C – columnar grains, E – equiaxed grains, SC – single crystal situated axially.

2

Structural Zones in Large Static Ingot. Forecasts for Continuously Cast Brass Ingot

Wołczyński W., Lipnicki Z., Bydałek A. W., Ivanova A. A.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 3

141--146

EN

Some metallographic studies performed on the basis of the massive forging steel static ingot, on its cross-section, allowed to reveal the following morphological zones: a/ columnar grains (treated as the austenite single crystals), b/ columnar into equiaxed grains transformation, c/ equiaxed grains at the ingot axis. These zones are reproduced theoretically by the numerical simulation. The simulation was based on the calculation of both temperature field in the solidifying large steel ingot and thermal gradient field obtained for the same boundary conditions. The detailed analysis of the velocity of the liquidus isotherm movement shows that the zone of columnar grains begins to disappear at the first point of inflection and the equiaxed grains are formed exclusively at the second point of inflection of the analyzed curve. In the case of the continuously cast brass ingots three different morphologies are revealed: a/ columnar structure, b/ columnar and equiaxed structure with the CET, and c/ columnar structure with the single crystal formation at the ingot axis. Some forecasts of the temperature field are proposed for these three revealed morphologies. An analysis / forecast of the behavior of the operating point in the mold is delivered for the continuously cast ingot. A characteristic delay between some points of breakage of the temperature profile recorded at the operating point and analogous phenomena in the solidifying alloy is postulated.

3

Influence of the reforging degree on the annihilation of the segregation defects in the massive forging ingots

Kowalski J., Pstruś J., Pawlak S., Kostrzewa M., Martynowski R., Wołczyński W.

Archives of Metallurgy and Materials

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2011

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Vol. 56, iss. 4

1029-1029

EN

The structural zones of the forging ingot have been distinguished. Some segregation defects within these zones have been described. An observation of the defects has been carried out with the use of scanning microscopy and scanning acoustic microscopy. Some defects revealed by the scanning acoustic microscopy have been subjected to the 3D computer visualization. A difference between localization and difference between morphology of carbides precipitated in the columnar structure and equiaxed structure has been shown. A given ingot was subjected to the plastic deformation with different reforging degree. The samples were taken from different segments of the reforged ingot. A density was determined for each ingot segment. A degree of consolidation was determined after ingot reforging. Once again the scanning acoustic microscopy was applied to determine the annihilation of the segregation defects in the forging ingot structure. A new definition of the consolidation factor after the reforging has been proposed.

PL

Wyrózniono strefy strukturalne we wlewku kuziennym. Opisano defekty segregacyjne w wyróżnionych obszarach jego struktury. Przeprowadzono obserwacje defektów z użyciem mikroskopu skaningowego oraz ultradźwiękowego. Dokonano trójwymiarowej komputerowej wizualizacji defektów odkrytych mikroskopem ultradźwiękowym. Pokazano róznice w lokalizacji i morfologii weglików wydzielonych w strukturze kolumnowej oraz w strukturze równoosiowej. Wybrany wlewek kuzienny poddano przeróbce plastycznej z róznymi stopniami przekucia. Pobrano próbki materiału z poszczególnych segmentów przekutego wlewka. Oceniono gęstość materiału w badanych segmentach wlewka. Oceniono stopień zagęszczenia materiału w wyniku przekucia. Ponownie użyto mikroskopu ultradźwiękowego aby ocenić zanik defektów segregacyjnych w strukturze wlewka kuziennego. Zaproponowano nowa definicję wskaźnika zageszczenia wlewka po przekuciu.