Effect of Chromium on the Solidification Process and Microstructure of Vermicular Graphite Cast Iron

The paper presents the results of studies of the effect of chromium concentration on the solidification process, microstructure and selected properties of cast iron with vermicular graphite. The vermicular graphite cast iron was obtained by an Inmold process. Studies covered the cast iron containing chromium in a concentration at which graphite is still able to preserve its vermicular form. The effect of chromium on the temperature of eutectic crystallization and on the temperature of the start and end of austenite transformation was discussed. The conditions under which, at a predetermined chromium concentration, the vermicular graphite cast iron of a pearlitic matrix is obtained were presented, and the limit concentration of chromium was calculated starting from which partial solidification of the cast iron in a metastable system takes place. The effect of chromium on the hardness of cast iron, microhardness of individual phases and surface fraction of carbides was disclosed.