This blog will cover the differences between Cast Iron and Ductile Iron in terms of physical and chemical properties and industrial applications.

Cast Iron:
Cast Iron is the most preferred material among our clients for housing and gearboxes that range from medium to large sizes. One of the main reasons is that cast iron has better working capability than Ductile Iron. Some of the other advantages include strength-to-weight ratio, corrosion resistance, high machinability, high strength by compression standards, lower costs, sound absorbing, structural rigidity, good casting, easy availability of the required raw materials and higher casting ability for complex and detailed shapes.

There are different grades of Cast Iron, as discussed in some of our previous blogs, as grade 20, grade 30 and so on. The different grades of the cast iron depend upon the iron’s chemical composition. One can alter the iron’s composition based on the applications in which it will find use. Some castings are designed to withstand high pressure, while some aren’t under any level of pressure. For instance, cast iron that falls between 20 and 30 finds application as a housing material.
This is because housing generally falls under high pressure category; the chemical composition of grade 30 cast iron is built to withstand a high yield strength of 30,000psi.

Ductile Iron:
Ductile iron usually goes into applications that require higher strength materials for withstanding greater pressures. Like cast iron, it is made by alteration of its chemical composition, in addition to the processes by which it is produced.  Ductile iron, compared to cast iron, is twice as strong and as durable as steel. Like cast iron, it exhibits several benefits such as corrosion resistance, excellent compression strengths, structural rigidity and strength-to-weight ratio.

However, there is something that differentiates cast iron from ductile iron, and that is that the chemical composition of ductile iron is more elastic and flexible than the former. This is because of the circular grain of ductile iron in comparison with the flaky grain of its counterpart. Whilst ductile iron is built to withstand greater pressures, it can still be flexible; however, there are advantages when it comes to ductile iron. It can be complicated to cast than cast iron, and needs various patterns because of its greater shrinkage rate.