Effect of cooling rate on eutectic cell count, grain size, microstructure,and ultimate tensile strength of hypoeutectic cast iron

This article describes a series of microstructural and strength studies per formed on hypoeutectic cast iron, which was sand cast using a variety of en d chills (metallic, nonmetallic, water-cooled, and subzero, respectively). The effects of cooling rate on the eutectic cell count (ECC), grain size, a nd the ultimate tensile strength (UTS) were evaluated. Attempts were also m ade to explain these effects and to correlate the UTS with ECC. It was foun d that subzero chilled and water-cool, chilled cast iron exhibit severe und ercooling compared to normal sand cast iron. It was concluded from this inv estigation that nucleation conditions are completely altered but growth con ditions prevail as usual, Therefore, undercooling during solidification is considered to be responsible for variation in ECC, grain size, microstructu re, and tensile strength.