Application of cast iron
Important types of cast iron:
Grey
Ductile
Compacted graphite
White
Malleable
Abrasion resistant
Nodular or spheroidal
Austenitic
Now let's discuss properties of each of them briefly.
White cast iron
Carbon is present here in the form of Iron carbide (Fe3C).
Its properties are
It has High compressive strength
It is difficult to machine
It has Good hardness
It has Resistance to wear
Gray cast iron
Carbon here is mainly in the form of graphite. It is inexpensive.
Its properties are
It has Good machinability
It has Good resistance to galling and wear
It has high compressive strength
It is brittle
Its properties are
It has High ductility
It has High strength
Malleable cast iron
They are made malleable with the help of annealing. They are used to make parts where forging is expensive like, brake supports, hubs of wagon wheels etc. They are in expensive.
Its properties are
They have High ductility
They are tougher than gray cast iron
They can be twisted or bent without fracture
They have excellent machining capabilities
5. Nodular or spheroidal cast iron
Here graphite is present in the form of spheres or nodules.
Its properties are
They have high tensile strength
They have good elongation properties
Advantages of cast iron
It has Good casting properties
It is available in large quantities, hence produced in mass scale. Tools required for casting process are relatively cheap and inexpensive. This results into low cost of its products.
It can be given any complex shape and size without using costly machining
It has three to five times more compression strength compared to steel
It has Good machinability (gray cast iron)
It has excellent anti-vibration (or damping) properties hence it is used to make machine frames
It has good Sensibility
It has excellent resistance to wear
It has constant Mechanical properties between 20 to 350 degree Celsius
It has very low notch sensitivity
It has Low stress concentration
It bears Low cost
It has Durability
It has Resistance to deformation
Disadvantages of cast iron
It is Prone to rusting
It has poor tensile strength
Its parts are section sensitive, this is due to slow cooling of thick sections.
failure of Its parts is sudden and total, it does not exhibit yield point.
It has poor impact resistance
Compared to steel it has poor machinability
It has High weight to strength ratio
It has High brittleness
It is Non machinable (white cast iron)
Applications of iron castings:
It is used in making following parts
It is used in making tractor parts, agricultural parts
It is used in making different machine parts
It is used in making automotive parts
It is used in making valve parts and pump parts
It is used in making marine parts.
It is used in making any kind of customized shape metal parts