Article – Trace elements and graphite shape degeneracy in nodular graphite cast Irons – Jacques LACAZE

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TRACE ELEMENTS AND GRAPHITE SHAPE DEGENERACY

IN NODULAR GRAPHITECAST IRONS

Jacques Lacaze CIRIMAT, ENSIACET, Universite ́de Toulouse, Toulouse, France

Copyright ©2016 American Foundry Society DOI10.1007/s40962-016-0115-6

Abstract

Graphite degeneracy in spheroidal graphite cast iron is acommon issue faced by foundries. It is generally asso-ciated with the presence of so-called poisoning elementsand may in some cases be suppressed by the addition ofother elements. Mastering these additions is not simple inpractice since industrial alloys do generally containmany elements that can affect graphite shape even whenpresent at low or trace levels. In this work, trace andlow-level elements are considered in relation with threesteps of microstructure formation: (1) nucleation ofgraphite; (2) growth of graphite; and (3) solid-statetransformations.

Keywords : nodular graphite cast iron, graphitedegeneracy, trace elements, eutectoid reaction

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