Shrinkage porosity of Gray, Ductile and Compacted graphite irons and its relationship with solidification structures

JUAN MASSONE ; MARCOS LÓPEZ; GRACIELA RIVERA; ROBERTO BOERI

Orlando

Simposio; Advances in the Science and Engineering of Casting Solidification, held at the TMS 2015 Annual Meeting & Exhibition in Orlando, Florida, March 15-19, 2015; 2015

TMS

This work compares the solidification macrostructure of eutectic Gray, Ductile and Compacted graphite iron as it is revels using the Direct Austempering After Solidicfication (DAAS) technique and determines the relationship between solidification structure and shrinkage porosity for the different cast irons.For all the irons, it was possible to verify that the solidification is dominated by the growth of large austenite dendrites that form a grain pattern similar to the morphology usually found in most metallic alloys. Differences in the grain size were observed as a function of the cooling rate during solidification.Using a special casting designed for the study of shrinkage porosity it was possible to verify in all the irons that dispersed shrinkage cavities form mostly inside the grains, and between the austenite dendrite arms.