Cast Iron has stood the test of times when it comes to strength and corrosion resistance for about four centuries. For every conceivable situation where strength and corrosion resistance are the full monty, ductile iron has delivered well: sewer pipes, manhole covers, water pipe, buildings, bridges to fire hydrants, and what not.

In Versailles, France you can find the oldest operating cast iron water main installed in 1664. In North America alone, you can find more than 500 municipalities with cast iron pipe that has been around close to 100 years.  Cast iron, because of its high durability and longevity, has withstood hundreds of years of above ground and underground service.

Ductile Iron founds its way into the commercial market in the 1960’s. The only thing that can differentiate ductile iron from cast iron is its ability to break without breaking. Ductile Iron is no different from cast iron in terms of ingredients. Again the difference lies not only in the quantity of carbon molecules, but their configuration. In the case of cast iron, the configuration carbon is in flake form, whereas in ductile iron, it is in nodular form.

Ductile iron is produced by addition of magnesium alloy to a molten iron of low sulphur and low phosphorous content. The addition of magnesium alloy brings about a significant change in the microstructure with the carbon in the iron taking up a nodular or spheroidal shape, in comparison to the flake form of graphite found in grey cast iron, while at the same time producing a finely grained iron matrix in the ferrite structure surrounding it. The change in the molecular structure makes ductile iron tougher, stronger and ductile.

Ductile iron is characterised by good corrosion resistance and mechanical properties. It can be machined, formed and heat treated such that it finds itself in a range of structural applications. Its service range and performance cannot be matched by any other material. The aforementioned reasons make ductile iron the most preferred material for utility poles in the future.