Cast Iron
Sarmad Shamim Cast Iron
We are providing a higher quality array of Cast Iron to or valuable clients. We are offering range of cast iron with high standard chemical specification which is designed and developed under our company with high grade material as per the global market norms and standards.
In order to reach out and respond to the various demands of our valued clients, we are able to offer cast iron bars at competitive prices.
Introduction
Cast iron is one of the oldest ferrous metals used in construction and outdoor ornament. It is primarily composed of iron (Fe), carbon (C) and silicon (Si), but may also contain traces of sulphur (S), manganese (Mn) and phosphorus (P). It has a relatively high carbon content of 2% to 5%. It is hard, brittle, nonmalleable (i.e. it cannot be bent, stretched or hammered into shape) and more fusible than steel. Its structure is crystalline and it fractures under excessive tensile loading with little prior distortion. Cast iron is, however, very good in compression. The composition of cast iron and the method of manufacture are critical in determining its characteristics.
Manufacturing Process of Cast Iron
Pig iron is re-melted along with large quantity of Scrap Steel, Scrap iron, Limestone and Coke. This mixture is infused with required amount of Carbon and Silicon. Mostly, the amount of Carbon lies between 2 to 3.5 % and the amount of Silicon lies between 1 to 3 %. This mixture is melted in an Electric Induction Furnace or an Electric Arc Furnace after which the molten metal is transferred to a holding furnace. The alloying elements that is added to cast iron determine its type. These alloyants, if not added in the right proportions can result in several casting defect such as short runs. Additives are added to prevent any such occurrences of defects.
Cast irons are divided onto the 4 groups
Each of these types has got unique physical and chemical properties:
- 1-Grey Cast Iron.
- 2-White Cast Iron.
- 3-Malleable Cast Iron.
- 4-Ductile Cast Iron.
1-White cast irons
In white cast iron, the carbon content is combined chemically as carbide of iron. White cast iron has superior tensile strength and malleability. It is also known as ‘malleable’ or ‘spheroidal graphite’ iron– hard and brittle highly wear resistant cast irons consisting of pearlite and cementite.
White cast irons are produced by chilling some surfaces of the cast mold. Chilling prevents formation of Graphite during solidification of the cast iron.
Applications: Brake shoes, Shot blasting nozzles, Mill liners, Crushers, Pump impellers and other abrasion resistant parts.
The composition of White Cast Iron is:
Carbon ( 2 to 2.5 % )
Silicon (1 to 1.3 %)
Manganese (0.25 to 0.8 %)
Sulfur (0.06 to 0.2 %)
Phosphorus (0.06 to 0.18) and Iron.
2-Grey cast irons
In grey cast iron, the carbon content is in the form of flakes distributed throughout the metal. Produced at slow cooling and consisting of ferrite and dispersed graphite flakes.
Grey cast irons possess high compressing strength, fatigue resistance and wear resistance. Presence of graphite in grey cast irons impart them very good vibration dumping capacity.
Applications: Gears, Flywheels, Water pipes, Engine cylinders, Brake discs, Gears.
The composition of Grey Cast Iron is:
Carbon (2.5 to 4 % ),
Silicon (1 to 3 % )
Manganese (0.25 to 1.0 %)
Sulfur (0.02 to 0.25 %)
Phosphorus (0.05 to 1.0 %) and Iron.
3-Malleable cast iron
Malleable cast iron – cast irons produced by heat treatment of white cast irons and consisting of ferrite and particles of free graphite.
Malleable cast irons have good ductility and machinability. Ferritic malleable cast irons are more ductile and less strong and hard, than pearlitic malleable cast irons.
Applications : Parts of power Train of Vehicles, Bearing Caps, Steering Gear Housings, Agricultural Equipment, Railroad Equipment.
The composition of Malleable Cast Iron is:
Carbon ( 2.16 to 2.90 % )
Silicon ( 0.90 to 1.90 %)
Manganese (0.2 to 1.25 %)
Sulfur (0.04 to 0.18 %)
Phosphorus (0.18 % Max) and Iron.
4-Ductile (Nodular) cast irons
Ductile (Nodular) cast irons – grey cast iron, in which graphite particles are modified by magnesium added to the melt before casting. Nodular cast iron consists of spheroid nodular graphite particles in ferrite or pearlite matrix.
Ductile cast irons possess high ductility, good fatigue strength, wear resistance, shock resistance and high modulus of elasticity.
Applications : Automotive Engine Crankshafts, Heavy Duty Gears, Military and Railroad Vehicles.
The composition of Ductile Cast Iron is:
Carbon ( 3.5 to 3.9 %)
Silicon ( 2.25 to 2.75 %)
Manganese (0.1 to 1 %)
Sulfur (0.03 % Max)
Phosphorus (0.1 % Max) and Iron.
