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The Effect of the Heat Flux Density on Microstructure of Surface Remeltings on C355 Alloy Castings

Orłowicz A. W., Mróz M., Tupaj M., Trytek A., Jacek M., Radoń M.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 2

35--38

EN

The paper presents results of a study on the effect of the flux density of heat carried away for the remelting area to substrate in the course of surface remelting with concentrated heat stream on values of structural parameters λ1D and λ2D of α(Al) phase dendrites in C355 alloy. The remeltings were made with the use of GTAW method, at arc current intensity I = 200 A and concentrated heat stream scanning speed vs = 200, 400, 600, and 800 mm/min. The used protective gas was argon supplied at rate of 20 l/min. It has been found that the increase of the rate of scanning with concentrated heat stream results in a change of the remelting-substrate separation surface shape consisting in reduction of the remelting width and depth. This increases the value of the flux density of heat transmitted from the remelting area to substrate which in turn acts in favor of reduction of structural parameters λ1D and λ2D characterizing α(Al) phase dendrites in C355 alloy.

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Wpływ parametru strukturalnego ═D dendrytów fazy α na intensywność zużycia ściernego odlewów ze stopu C355 uszlachetnionych skoncentrowanym strumieniem ciepła

Mróz M., Orłowicz W., Tupaj M.

Tribologia

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2008

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nr 1

101-109

PL

W pracy przedstawiono wyniki badań wpływu szybkiej krystalizacji realizowanej z wykorzystaniem metody GTAW na mikrostrukturę i właściwości użytkowe odlewu ze stopu C355. Materiał do badań stanowiły próbki odlane do formy metalowej, które uszlachetniono powierzchniowo z zastosowaniem różnych wartości parametrów technologicznych metody GTAW. Określono związek pomiędzy parametrem strukturalnym ═D a intensywnością zużycia ściernego.

EN

The results of the effect of rapid solidification, realized with GTAW method, on the structure and properties of C355 alloy was presented in the paper. The sample was prepared in the permanent mould and refined surface with variable parameters of GTAW process (welding current, arc advance speed). The correlation were applied in order to the relation between the structure parameters and wear intensity.

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Wpływ wydzieleń krzemu na intensywność zużycia ściernego odlewów ze stopu C355 uszlachetnionych powierzchniowo skoncentrowanym strumieniem ciepła

Orłowicz W., Mróz M., Tupaj M.

Rudy i Metale Nieżelazne

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2008

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R. 53, nr 8

488-492

PL

Na powierzchni próbek ze stopu C355 wykonano nadtopienia z wykorzystaniem metody GTAW. Proces prowadzono w atmosferze argonu, przy zmiennej w zakresie od 200 do 800 mm/min prędkości skanowania łukiem elektrycznym. Dla materiału z obszaru nadtopień oceniono parametr strukturalny L/MAX, Lambda/E, mikrotwardość oraz zużycie ścierne. Związek pomiędzy prędkością skanowania łukiem elektrycznym, parametrami mikrostruktury, intensywnością zużycia ściernego i twardością opisano z wykorzystaniem metody regresji krokowej.

EN

Surface of the C355 alloy samples was refined by the GTAW method fusions. The process was conducted in an argon atmosphere at variable scanning rate of an electric arc, ranging from 200 to 800 mm per minute. The structural parameter L/MAX, Lambda/E microhardness and frictional wear were assessed for the fused area of the material. Correlation between electric arc scanning rate, microstructure parameters, frictional wear intensity and hardness has been described using stepwise regression method. The results indicate that refining of the top surface of the C355 alloy casts with concentrated heat flux leads both to significant decrease in a scope of silicon precipitation in the eutectic area and to the reduction of a distance between precipitates. Microstructure of the fusion areas, which is crystallization rate dependant, can be controlled by altering the electric arc scanning rate. Refining of the casts surface by means of concentrated heat flux made that both structural parameter L/MAX and structural parameter Lambda/E were three times smaller. It was found that the structural parameter L/MAX is more sensitive to the variation in an electric arc scanning rate (threefold change) than the structural parameter Lambda/E (twofold change). Application of the GTAW method for refining of the C355 alloy casts enabled obtaining the microstructure characterized by high hardness and low value of the coefficient of friction wear intensity. The coefficient of friction wear intensity dropped eightfold. Reduction of friction wear intensity of the concentrated heat flux refined material in comparison to the base material results from the decrease in the scope of silicon precipitation and from the reduction of a distance between precipitates in the eutectic area.