Examination of the solidification macrostructure of spheroidal and flake graphite cast irons using DAAS and ESBD

Abstract

This investigation focuses on the study of the solidification macrostructure of sand cast flake and spheroidal graphite cast irons. The macrostructure is revealed by using a special technique developed earlier by the authors, called Direct Austempering After Solidification. The observations make use of conventional metallography and Electron Back Scattering Diffraction. The latter technique allows a more detailed observation of the morphology of the austenite grains and the microstructure of the matrix. The results of Electron Back Scattering Diffraction validate the observations made using the macrographic technique. It is verified that the solidification of both flake and spheroidal graphite cast irons is dominated by the growth of large austenite dendrites that form a grain pattern similar to that usually found in most metallic alloys.