Microstructure and Properties of High Carbon Equivalent Gray Cast Iron Modified by Rare Earth

Microstructure and properties of the high carbon equivalent gray cast iron modified by the rare earth metal are investigated by optical microscopy, scanning electronic microscopy, Brinell hardness and tensile testing. The results show that the primary austenite dendritic is refined, and the morphology of graphite is transformed from A-type to D-type undercooling graphite with increment of the rare earth metal (REM), even with the vermicular graphite present. The lamellae are becoming thinner with increment of rare earth metal. There are double peaks between the addition of the rare earth metal and the tensile strength/hardness. The iron would have the best comprehensive property when 0.30% REM is added.