Study of microstructure of thick wall ductile iron castings

Ductile Iron castings with section thickness 60mm, 70mm & 80mm were produced using manufacturing process in which the chemical composition was adjusted to guarantee the formation of spheroidal graphite during solidification. Simultaneously other parameters like carbon equivalent, tapping temperature, inoculation and magnesium residuals were monitored. Microstructure and its constituents of these thick wall castings were characterized using an image analyzer. Matrix structure and graphite forms were investigated as a function of section thickness. Pearlite content, nodule count and nodularity decreases with increasing section thickness where as nodule size increases.