This week we attempt to present a generic overview of ductile iron.  Ductile iron is also known as nodular iron or graphite iron. It was first patented in 1948, but it was only after a decade of intense technological research and development that its application as an engineering material was proved indispensable.

Graphite is present as spheroids in ductile iron and provides some unique properties consequently (it appears as individual flakes in grey iron). A small quantity of Nodularizer is included in the molten iron of a suitable composition, in addition to the restriction of specific minor elements in the base iron to guarantee non-interference in graphical spherical formation. The processing of ductile iron is made reliable using a number of control procedures.

Highlights of Ductile Iron: 

• There are a number of advantages of ductile iron in terms of casting because of its high silicon and carbon content.
• The impact of the graphite spheroids is minimal on the mechanical characteristics of ductile iron.
• Ductile iron exhibits a stress/strain relationship and significant range of yield strengths.
• Ductile Iron can easily convert to steel castings, fabrications and forging because of its excellent machinability and castability. The ductile iron also has higher properties and a lower density, leading to considerable cost savings.
• It exhibits several design properties including a unique combination of low cost manufacturing, toughness, endurance and reliability.

Different grades of ductile iron are produced by controlling the matrix structure around the graphite in the casting process, or later via heat treatment. There are slight compositional differences between various grades of ductile iron. These differences are necessary to create the required matrix microstructures. Special applications are deemed possible due to the unique characteristics of ductile irons, high alloy ductile irons, and Austempered Ductile Irons (ADI).

When it comes to the applications of Ductile Iron, they are extensively used in gear boxes, frames, pumps and cable drums; thanks to its greater ductility and strength. The above examples make up only a selective number of products that can be manufactured using ductile iron.