Ductile Iron retains the corrosion resistance of Cast Iron but has more than double the tensile strength [Cast Iron- 180 MPa (min), Ductile Iron - 420 MPa (min)]. The essential difference between Ductile and Cast Iron lies in the shape of the graphite in the microstructure of the metal. In Cast Iron, the graphite is present in plate-like flakes, which makes Cast Iron brittle. But in Ductile Iron, the shape of the graphite becomes a spheroidal nodule, which offers better mechanical properties and makes Ductile Iron sturdy, structurally stronger and shock-proof.