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Analysis of segregation process using the broken line model. Numerical realization

100%

Suchy J. S. , Mochnacki B. , Prażmowski M.

Archiwum Odlewnictwa

2003

tom R. 3, nr 10

235--240

In the paper [1] the basic idea of simplified model of macro-segregation process called 'a broken line model' is presented. Here, the details concerning the algorithm realizing the numerical simulation of the process are discussed. The examples of computations concern both the constant solidification rate and the time-dependent one.

W pracy [1] omówiono istotę uproszczonego modelu makrosegregacji nazwaną przez autorów metodą linii łamanej. W niniejszym artykule przedstawione zostaną niektóre szczegóły dotyczące algorytmu realizującego obliczenia numeryczne. Przykłady obliczeń dotyczą zarówno zadań, dla których założono stałą szybkość krzepnięcia, jak i zadań, dla których szybkość krzepnięcia zmienia się w czasie.

Evaluation of chemical heterogeneity of a 90-ton forging ingot

100%

Machovcak P. , Opler A. , Carbol Z. , Trefil A. , Merta K. , Tkadleckova M. , Michalek K.

tom Vol. 58, nr 1

22--27

Purpose: This article describes performance of the experimental 90-ton forging ingot casting, the way of cutting, the methodology of chemical analysis and the results of that investigation. Design/methodology/approach: The experimental ingot 8K91SF weighing almost 90 tons was cast due the performance a detailed analysis of the current state of casting and solidification. The ingot was cut and macrostructure and chemical heterogeneity of the ingot was evaluated in detail. The standard method used in metallurgical analytics - analyses using optical emission spectrometers - was not applicable due to the large number of required analyzes. Thus, the mobile optical spectrometer SPECRTOTEST was used. Sulfur prints and fluid penetration tests were performed due to detect macroscopic distribution of sulfur and to locate surface-breaking defects. Findings: Current level of segregations of selected elements in real 90-ton steel ingot was detected. Also mutual mixing of two heats needed for the production of this ingot was verified. Research limitations/implications: Future research is focused on determination of inclusion content in selected parts of experimental ingot and on the level of micro-segregations. We are limited by the accuracy of chosen analytical method, which is also discussed in the paper. Practical implications: The gained knowledge is used to specification of the setting of boundary conditions of the numerical simulations, which should help to optimize the production technology of casting heavy forging ingots and minimize the level of segregation in ingots. Originality/value: New knowledge concerning mutual mixing of two heats needed for bottom casting of heavy forging ingot are presented in this paper. Distribution of segregation in so heavy ingot was detected. Results are the base for further investigations in macro-segregations and for the improving the accuracy of results of numerical simulations.

Modelling of binary alloy volumetric solidification

84%

Mochnacki B. , Suchy J. S. , Prażmowski M.

tom R. 1, nr 2

244--250

In the paper the numerical model of heat transfer and segregation of alloy component proceeding during the volumetric solidification process is discussed. It is assumed that the temperature field in domain of casting is only time-dependent. The macrosegregation model corresponds to the lever arm and the Scheil one. In numerical realization the differential equation describing the solidification and cooling processes in casting domain is solved using the Euler method. The macrosegregation model allows to take into account the change of temperature corresponding to the beginning of solidification process.

W pracy omówiono model numeryczny przepływu ciepła i makrosegregacji w procesie krzepnięcia objętościowego. Rozważano zadanie, w którym temperatura w odlewie jest tylko funkcją czasu. Model makrosegregacji odpowiada modelowi pełnego mieszania i modelowi Scheila. Odpowiednie równania różniczkowe wyprowadzone w pracy wynikają z bilansów energii i masy.