A nanobainitic matrix composing of nanoscale α phase and carbon-riched γ phase was obtained for the ductile iron by austempering treatment. The microstructure and properties of ductile iron were compared with GCr15. The microstructural characteristic gave rise to a good strength with an ultimate tensile strength higher than 1200?MPa, which was comparable and even superior to conventionally forged steels. The friction coefficient of the ductile iron was approximate 1/3 compared with that of commercial GCr15 under dry sliding wear condition, which was related to the existence of homogeneously distributed spheroidal graphite in ductile iron. The low friction coefficient and moderate strength resulted in a superior wear resistance of ductile iron with nanobainitic matrix by contrast to GCr15.
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