Spherodial Graphite Iron (S.G)
Spheroidal graphite iron, which is also known as ductile iron, was discovered in 1943. Magnesium addition before pouring was found to cause the formation of nodular graphite instead of flakes. Thus, the material of spheroidal graphite iron, which has high tensile strength and ductility, was found as new material. The mechanical properties of cast iron were further enhanced by this process. As a result, it has been used in almost all fields of engineering since then. Since it is an economic material, it is used to replace existing steel castings or forgings, thus providing significant cost advantages.
For detailed grades, please see the table at bottom of this page…
STRENGTH: Offers tensile strengths of up to 900N/mm2 (Austempered Ductile Iron castings offer higher strength values).
DUCTILITY: Percent elongations above 20% (Lower grades only)
HIGH CORROSION RESISTANCE: Offers better corrosion resistance than other ferrous metals.
HIGHER MACHINABILITY: Free graphite in the structure of the material facilitates machining operations (chip formation).
COST PER UNIT STRENGTH: Provides significant cost advantages compared to most materials.
METALLURGY: The composition of spheroidal graphite cast iron is slightly different from that of grey iron, however it offers better ductility and strength. Because of the nodular microstructure of the material, it is also called as nodular cast iron. In the material’s microstructure, graphite spheroids (nodules) are observed instead of flakes. On the other hand, the graphite flakes, which provide unique properties to grey iron, decrease the mechanical strength, interrupt the continuity of the metallic matrix, and prevent ductility. Moreover, the sharp edges of the graphite flakes cause internal stresses which further reduce the strength. Thanks to graphite spheroids in its microstructure, SG iron eliminates this problem and allows the continuity of the metallic matrix, thus enhances ductility. Since S.G. iron has no sharp edges it has no stress raisers i.e. nothing reduces the strength of the metal matrix.
For detailed features, please see the table at bottom of this page…
Detailed Material Properties Table
Please kindly click on below PDF document to see detailed material properties table.