GREY IRONGrey Cast Iron is made by remelting pig iron. It is an alloy of Carbon and Iron. Small amounts of Silicon, Phosphorus, Manganese and Sulphur are also present in it. The reasons behind its popularity are: ability to make complex structures and low cost. In addition, the excellent properties of Grey Cast Iron have made it one of the most widely used alloys.
- Relatively inexpensive.
- Easier to cast due to expansion.
- Grey iron also has unique properties which are useful for applications with sliding surfaces like hydraulic pistons.
- Free graphite within the structure acts as a lubricant and aids machining.
- Excellent damping and wear characteristics.
- Used where tensile strength and ductility are non-critical.
- Engine blocks.
- Valve bodies.
DUCTILE IRONDuctile Iron is also known as SG Iron, Nodular Cast Iron and Spheroidal Graphite Iron. The main characteristics of this material is the structure of the graphite. In Ductile Iron, the graphite is in the form of spherical nodules (hence the name Spheroidal Graphite) rather than flakes as in Grey Iron. This nodular graphite structure inhibits the creation of linear cracks hence the ability to withstand distortion.
- High tensile strength and ductility compared to grey iron.
- Tensile strength and ductility can vary across the range of grades allowing for irons to be suitable for a wide range of applications.
- Load bearing applications.
- Replaces steel for many applications and achieves a significant cost saving.
- Easy to machine.
- Corrosion resistant compared to other ferrous metals.