Chemical composition of chosen phase constituents in austempered ductile cast iron

Abstract

Abstract A procedure a for multi-step characterization of microstructural features observed in austempered ductile cast iron (ADI), was proposed based on the results of microscopic examinations, a local X-ray microanalysis and EBSD-based crystallographic evaluation. The polyphase complex microregions having an increased content of alloying elements such as Mo, Cr, Mn in comparison with that estimated for the alloy's matrix, were observed in the examined material. As a first step, a classification of microregions was performed based on their morphology and specific distribution in the alloy's microstructure. Subsequently, by using established criteria for the selection of microanalysis data for a further microregions discrimination, several groups of particles characterized by a particular ratio of the alloying elements, were distinguished. The particles were classified based on the specific range of the carbide stabilizers concentration revealed, then were ascribed in situ to two types of carbides identified by means of EBSD analysis. Furthermore, the effect of heat treatment conditions on the evolution of the chemical composition of the microregions was examined experimentally and discussed.