Influence of alloy element distributions on austempered ductile irons

ABSTRACT

The influence of alloy element distributions on austempered ductile iron microstructure and austempering treatment was analysed by a cellular automaton model that considers the ausferritic and martensitic transformations. The initial microstructure is modelled as spherical graphite nodules inserted in an austenitic matrix, in which the alloy elements are distributed in a uniform or non-uniform way. The study is performed for different chemical compositions and graphite nodule sizes. Delays in the development of ausferritic transformation are produced by the increment of graphite nodule size and the presence of alloy element microsegregations. Moreover, microsegregation reduces the final volume fraction of ferrite platelets. The predicted retained austenite volume fraction is in good agreement with the experimental measurements reported in the literature.

KEYWORDS:

• Austempered ductile iron
• alloy element distributions
• phase transformations
• cellular automaton modelling

Acknowledgments

During the course of this research A.D. Boccardo had a postdoctoral scholarship from CONICET. L.A. Godoy is a member of the research staff of CONICET.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

A. D. Boccardo  http://orcid.org/0000-0003-3299-2510

P. M. Dardati  http://orcid.org/0000-0002-3294-2962

Additional information

Funding

This work was supported by a grant from Universidad Tecnológica Nacional [ASUTNCO0004735].