In spite of the progress achieved during the first half of this century in the development of Gray and Malleable Irons, foundrymen continued to search for the ideal cast iron an as cast "gray iron" with mechanical properties equal or superior to Malleable Iron. J.W. Bolton, speaking at the 1943 Convention of the American Foundrymen's Society (AFS), made the following statements.

"Your indulgence is requested to permit the posing of one question. Will real control of graphite shape be realized in gray iron? Visualize a material, possessing (as-cast) graphite flakes or groupings resembling those of malleable iron instead of elongated flakes."

A few weeks later, in the International Nickel Company Research Laboratory, Keith Dwight Millis made a ladle addition of magnesium (as a copper-magnesium alloy) to cast iron and justified Bolton's optimism - the solidified castings contained not flakes, but nearly perfect spheres of graphite. Ductile Iron was born!

Five years later, at the 1948 AFS Convention, Henton Morrogh of the British Cast Iron Research Association announced the successful production of spherical graphite in hypereutectic gray iron by the addition of small amounts of cerium.

At the time of Morrogh's presentation, the International Nickel Company revealed their development, starting with Millis' discovery in 1943, of magnesium as a graphite spherodizer. On October 25, 1949, patent 2,486,760 was granted to the International Nickel Company, assigned to Keith D. Millis, Albert P. Gegnebin and Norman B. Pilling. This was the official birth of Ductile Iron and the beginning of over 50 years of continual growth worldwide, in spite of recessions and changes in materials technology and usage. What are the reasons for this growth rate, which is especially phenomenal, compared to other ferrous castings?