Analysis of carbon diffusion during bainite transformation in ADI

• Autorzy: Ławrynowicz Z. , Dymski S.
• Języki publikacji: EN

Abstrakty

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.

Słowa kluczowe

EN

carbon diffusion; decarburisation; bainite; ductile iron (ADI)

PL

dyfuzja węgla; odwęglanie; bainit; żeliwo sferoidalne; ADI

• Wydawca: Komisja Odlewnictwa Polskiej Akademii Nauk Oddział w Katowicach
• Czasopismo: Archives of Foundry Engineering
• Rocznik: 2007
• Tom: Vol. 7, iss. 3
• Strony: 87--92
• Opis fizyczny: Bibliogr. 19 poz., rys., tab.

Twórcy

autor

Ławrynowicz Z.

autor

Dymski S.

• University of Technology and Life Sciences, Mechanical Engineering Faculty, al. Kaliskiego 7, 85-796 Bydgoszcz, Poland,

Bibliografia

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