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Affect of decarburization times of bainitic ferrite laths on the microstructure in FE-CR-C steel

Ławrynowicz Z.

Journal of Polish CIMAC

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2011

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Vol. 6, no 3

127-136

EN

The purpose of the present paper is to demonstrate how a thermodynamic method can be used for solving a problem of the decarburisation of bainite laths. The paper presents an investigation of the time required for the diffusion of carbon out of supersaturated laths of ferrite into the retained austenite. This should in principle enable to examine the partitioning of carbon from supersaturated ferrite laths into adjacent austenite and the carbon content in retained austenite using analytical method. The obtained results illustrates that the estimated times are not capable of decarburising the sheaf of ferrite included thick laths of bainitic ferrite during the period of austempering. A consequence of the precipitation of cementite from austenite during austempering is that the growth of bainitic ferrite can continue to larger extent and that the resulting microstructure is not an ausferrite but it is a mixture of bainitic ferrite, retained austenite and carbides.

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Decarburisation of bainitic ferrite laths and its influence on the microstructure in Fe-Cr-Si-C steel

Ławrynowicz Z.

Advances in Materials Science

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2011

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Vol. 11, nr 2(28)

56-64

EN

The paper presents an investigation of the time required for the diffusion of carbon out of supersaturated laths of ferrite into the retained austenite. The purpose of the present paper is to demonstrate how a thermodynamic method can be used for solving a problem of the decarburisation of bainite laths. This should in principle enable to examine the partitioning of carbon from supersaturated ferrite laths into adjacent austenite and the carbon content in retained austenite using analytical method. The obtained results illustrates that the estimated times with the reference to the executed thermal processing are not capable of decarburising the sheaf of ferrite included thick laths of bainitic ferrite during the period of austempering. A consequence of the precipitation of cementite from austenite during austempering is that the growth of bainitic ferrite can continue to larger extent and that the resulting microstructure is not an ausferrite but it is a mixture of bainitic ferrite, retained austenite and carbides.

3

Decarburisation Of Ferrite Laths During Bainite Reaction In Adi

Ławrynowicz Z., Dymski S.

Journal of Polish CIMAC

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2009

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Vol. 4, no 3

65-72

EN

The paper presents an investigation of the time required for the diffusion of carbon out of supersaturated laths of ferrite into the retained austenite. Experimental measurements of volume fraction of bainitic ferrite and volume of the untransformed austenite indicate that there is a necessity of carbides precipitation from austenite. A consequence of the precipitation of cementite from austenite during austempering is that the growth of bainitic ferrite can continue to a larger extent and that the resulting microstructure is not an ausferrite, but is a mixture of bainitic ferrite, retained austenite and carbides. The carbon concentration in retained austenite demonstrates that at the end of bainite reaction the microstructure must consist of not only ausferrite but additionally precipitated carbides.

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Analysis of carbon diffusion during bainite transformation in ADI

Ławrynowicz Z., Dymski S.

Archives of Foundry Engineering

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2007

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Vol. 7, iss. 3

87-92

EN

The paper presents an investigation of the time required for the diffusion of carbon out of supersaturated sub-units of ferrite into the retained austenite. The analytical model estimates the decarburisation time of the sub-units of supersaturated bainitic ferrite. The purpose of the present paper is to demonstrate how a thermodynamic method can be used for solving a problem of the decarburisation of bainite subunits and carbon diffusion distances in the matrix of ADI. This should in principle enable to examine the partitioning of carbon from supersaturated ferrite plates into adjacent austenite and the carbon content in retained austenite using analytical method. The diffusion coefficient of carbon in austenite is very sensitive to the carbon concentration and this has to be taken into account in treating the large concentration gradients that develop in the austenite. The results are discussed in the context of displacive mechanism of bainite transformation. Experimental measurements of volume fraction of bainitic ferrite and volume of the untransformed austenite indicate that there is a necessity of carbides precipitation from austenite. The necessary carbon diffusion distance in austenite also illustrates that the estimated time is not capable of decarburising the ferrite subunits during the period of austempering. A consequence of the precipitation of cementite from austenite during austempering is that the growth of bainitic ferrite can continue to larger extent and that the resulting microstructure is not an ausferrite but is a mixture of bainitic ferrite, retained austenite and carbides.

5

Problemy występujące przy spawaniu i naprawie spoin stali różnorodnych

Tasak E., Ziewiec A., Ziewiec K.

Archiwum Odlewnictwa

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2006

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R. 6, nr 21/2

221-227

PL

W artykule przedstawiono mechanizm powstawania warstwy odwęglonej przy obróbce cieplnej różnorodnych stali oraz wskazano, że obecność odwęglenia może być jedną z możliwych przyczyn awarii urządzeń energetycznych. Wykazano, że istnieje możliwość prognozowania zamian struktury SWC metodami obliczeniowymi.

EN

The paper presents mechanism of formation of decarburised layer during the heat treatment of dissimilar steels and it is showed that the decarburisation may be the one of possible reasons for failure of appliances in power industry. It is proved that it is possible to forecast the structure evolution of the heat affected zone by means of numeric methods.