Introduction
Spheroidal Graphite Iron is a type of cast iron which is obtained by adding graphite to iron in a particular structure. It is usually referred to as spheroidal graphite iron (SGI) or nodular iron due to the nodular shape of the graphite. It is a very strong, high strength material due to the spheroidal shape of the graphite and is used in a wide range of applications in engineering and automotive industries.
History
The first spheroidal graphite iron was produced in Germany in 1948. The first production process involves the introduction of elements like magnesium, cerium and rare earths in molten iron which is then percussion melted to form the graphite spheres by nucleating the graphite. This process was then improved and perfected in the 1980s by using aluminum-boron-silicon treatment which gives superior properties like better ductility and wear resistance.
Chemical Composition
Spheroidal graphite iron consists of an alloy of iron, carbon and silicon with traces of aluminum and magnesium. The chemical composition of the iron is controlled by standardized test methods such as ASTM A-48 for chemical analysis and EN 1083 for spheroidization. The main components are iron (Fe), carbon (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), boron (B), aluminum (Al) and magnesium (Mg).
Properties
Spheroidal graphite iron has many unique mechanical and physical properties which makes it suitable for various applications in engineering and automotive industries. Compared to other cast iron alloys, it has higher strength, ductility and fatigue strength, higher damping capacity and improved wear resistance. It also has excellent corrosion resistance because of its magnetite type structure which acts as a barrier coating against corrosion.
Applications
Since spheroidal graphite iron has a low density, high strength and a range of attractive properties, it is used in a variety of industries like automotive, aerospace, construction and industrial machinery. Automotive applications include engine blocks, cylinder heads, gearboxes, transmission housings, suspension components and exhaust manifolds. It is also used in industrial machinery such as pumps, compressors, blowers, turbines, bearings and gears.
Conclusion
Spheroidal graphite iron is a type of cast iron which is obtained by adding graphite to iron in a particular structure. It is a very strong, high strength material due to the spheroid shape of the graphite and is used in a wide range of applications in engineering and automotive industries. The main components are iron, carbon, silicon, manganese, phosphorus, sulfur, boron, aluminum and magnesium which give it its unique mechanical and physical properties. It is used in automotive applications such as engine blocks, cylinder heads, gearboxes, transmission housings and suspension components as well as industrial machinery such as pumps, compressors, blowers, turbines and bearings.
