Talking of ductile iron, the patent to make ductile iron was given to the three Keith Mills, Alber Gagnebin and Norman Piling in the year 1943 which allowed them to make it, ductile iron, by using magnesium to strengthen cast iron. There was witnessed a rise in the popularity of the use of ductile iron in a number of commercial applications and this could be traced and attributed to the many useful qualities that it has. Even though ductile iron is a type of cast iron, it has features that make it more resistant to wear and use. This is of course the result of the round graphite structures that are cast into the metal. It is these particular structures that add to the quality in the ductile iron, that is its ability to withstand greater impact while at the same time allowing for better elongation.

See ductile castings

There are other names with which ductile iron actually goes with and these are such as spheroidal graphite cast iron or nodular cast iron. While regular cast iron as well happens to be containing some bits of graphite, it should never be mistaken for ductile iron anyway. The granules in regular cast iron appear as squiggly lines and not the spherical ones as often seen in the ductile cast iron. Ductile iron is made up of iron, which is the major component forming up to 94% of the whole, and the remaining is a combination of the different materials such as carbon, silicon, manganese, phosphorous and magnesium. The other materials that can be added to it include copper which is used to boost its strength and nickel and chromium as well that do improve its resistance to corrosion effects.

More on gray iron

Actually looking at the above, one thing that we see that seems to be making the use of ductile iron so popular for a variety of the commercial uses is the ductility in the fact that they happen to be a lot stronger as compared to cast iron. In fact looking at the tensile strengths of the two kinds of irons, ductile cast iron offers a tensile strength that is double the one offered by the cast iron. Thanks to the superior ductility of the ductile cast iron, items made of ductile iron will be such that you will be able to hammer on as many times as you can without cracking, breaking or chipping which is unlike what we see in those made of cast iron. Given this, ductile iron can be said to be an ideal material for those applications that involve lots of pressure.

More info https://www.youtube.com/watch?v=qjJknBWjoeM