Inoculation of primary austenite in grey cast iron

Primary austenite is the least investigated microstructural component of grey cast iron. It is the first phase to be nucleated in the liquid metal and it grows in a dendritic manner, followed by growth of the eutectic phase. This paper describes an investigation on three potential nucleating agents to promote the nucleation of primary austenite in grey cast iron under industrial conditions. A direct austempering after solidification (DAAS technique) was used to determine the number of primary austenite grains. A colour etching technique was used to reveal the primary austenite grains and the eutectic cells. The results show that properly chosen nucleation agents significantly promote the number of primary austenite grains. Furthermore, the authors show that the eutectic cell size and the morphology of the graphite are obviously influenced by the primary solidification in grey cast iron. The increased nucleation of austenite grains resulted in an increased number of eutectic cells.