Carbon diffusion during bainite reaction in austempered ductile iron

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

Abstrakty

EN

The paper presents an investigation of the carbon concentration in the residual austenite and the time required for the diffusion of carbon out of supersaturated subunits of ferrite into the retained austenite. Experimental measurements of volume fraction of bainitic ferrite and volume of the untransforrned 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 larger extent and that the resulting microstructure is not an ausferrite but is a mixture of bainitic ferrite, retained austenite and carbides. Additionally, carbon concentration in the residual austenite was calculated using volume fraction data of austenite and a model developed by Bhadeshia based on the McLellan and Dunn quasi-chemical thermodynamic model. The comparison of experimental data with the T0, T0' and Ae3' phase boundaries suggests the likely mechanism of bainite reaction in cast iron is displacive rather than diffusional. 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.

Słowa kluczowe

EN

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

• Wydawca: Politechnika Gdańska
• Czasopismo: Advances in Materials Science
• Rocznik: 2008
• Tom: Vol. 8, nr 1(15)
• Strony: 75--87
• Opis fizyczny: Bibliogr. 27 poz., rys., tab.

Twórcy

autor

Ławrynowicz Z.

autor

Dymski S.

• Department of Materials Science and Engineering, Mechanical Engineering Faculty, University of Technology and Life Sciences in Bydgoszcz, Bydgoszcz, Poland

Bibliografia

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