Ductile cast iron
Ductile cast iron
The term 'cast iron' covers a wide variety of iron, carbon and silica alloys. Discovered in the 1940s, ductile cast iron is produced thanks to the addition of a small amount of magnesium to the molten grey cast iron. This process gives it exceptional properties in terms of mechanical resistance and bending.
Ductile cast iron is a real technological innovation.
Grey cast iron
The resistance and durability of grey cast iron, the material used before the advent of ductile cast iron, are widely known : in 1664 France's King Louis XIV had a network of grey cast iron pipes built to transport water from the Marly-sur-Seine pumping station to the water fountains and in the town of Versailles. These pipes have been in service for more than 330 years.
A micrographic observation of grey cast iron reveals that the carbon crystallizes in the form of long, narrow graphite flakes. These encourage a concentration of constraints, which are potential sources of the onset of cracks when the material is subjected to traction stresses.
The discovery of ductile cast iron
In 1943, a major discovery was made : the introduction of a small amount of magnesium into the grey cast iron caused the carbon to no longer crystallize in the form of flakes but in graphite spheres. A new material was born : ductile cast iron. Spheroidal graphite confers on cast iron exceptional mechanical properties : very high yield strength and also great resistance to traction and impacts. These qualities are indispensable for the installation of drinking water and sewerage conveyance networks.
A small bar of twisted ductile cast iron with astonishing properties was imported from the U.S. in 1949 by Jean CAVALLIER, a member of the family that founded Pont-à-Mousson. The ductile cast iron manufacturing process was industrialized in 1960.