means that it can get globular graphite through spheroidizing and inoculation，improve the mechanical properties of cast iron effectively, ductile Iron also especially improves the plasticity and toughness , it gets strength which is higher than the steel .
Ductile Iron is a kind of high strengthmaterial which develops from 1950s，ductile Iron’s comprehensive performance is close to steel，it is based on the excellent performance，ductile Iron has been successfully used in casting complex stress, strength, toughness, wear resistance requirements of the higher parts. Ductile iron has been the rapid development of casting iron material which application is very extensive. “replacing steel with iron”mainly refers to the ductile iron.
Ductile iron castings almost gets application in all major industrial sectors，these departments have requirments of high strength, plasticity, tenacity, thermostability or low temperature ,corrosion resistance and dimensional stability,etc.
In order to satisfy these changes which are in the conditions of using ，ductile iron has many numbers , it offers a wide range of mechanical and physical properties.
The passage above talks about the concept of ductile iron