CAST IRON TYPES

   

        

        Cast iron usually refers to grey  cast iron but also identifies a large group of  ferrous alloys, which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured due to its carbide impurities which allow cracks to pass straight through. Grey cast iron is named after its grey fractured surface, which occurs because the graphitic flakes deflect a passing crack and initiate countless new cracks as the material breaks.

Properties of Grey Cast  Iron:

• Alloy of Carbon / Silicon / Iron
• Carbon 2.5-3.8%, Silica 1.1-2.8%, Manganese 0.4 – 1%, Phosphrous 0.15%, Sulphur 0.1%
• Tensile Strength 150 – 350 N per Sq mm.
• Can be cast into desired shape in sand mould
• High compressive strength
• Lowest Melting point
• Posses high fluidity & can be cast into complex shapes
• Better machinability
• High resistance to wear
• High vibration damping capacity
• Low ductility

Grey Cast Iron Uses:

•   Machine Tool structures – Bed, Frames and details
•   Gas or water pipes – under ground purposes
•   Man hole covers
• Cylinder Blocks, Heads for IC Engines
•   Tunnel Segments
•   Frames of electric Motor
•   Ingot Moulds
•  Sanitary-wares
•  Piston Rings
•   Rolling Mills
•  General Machining parts
• House Hold appliances

Properties of Malleable Cast Iron:

•   Can be hammered and rolled to obtain different shapes
•   Carbon- 2-3%, Silica 0.6-1.3 %, Manganese 0.2 – 0.6%, Phospherous 0.15%, Sulphur 0.1%
•   Available in Three forms - 1) Ferritic Matrix, 2) Pearlite Matrix 3) Alloy Malleable
•   High yield strength
•  High Young’s Modulus
•   Low coefficient of Thermal Expansion
•  Good wear resistance
•  Good vibration damping capacity
•   Low to moderate cost

Malleable Cast Iron Uses:

•  Automotive Industry
• Rail Road & Marine
•  Agricultural Implements
•   Electrical Line, Hardware
• Conveyor chains links
•  Gear case
•  Universal Joints yoke
•  Truck’s Axle Assembly
• Automotive Crank shaft
•  Crankshaft Sprocket

Properties of Nodular / Sproidal Graphite Cast Iron:

•   Very good machinability
•   Carbon 3.2-4.2%, Silica 1.1-3.5%, Manganese 0.3-0.8%, Phosperous 0.08%, Sulphur 0.2%
•   Moderate Damping capacity ( between Cast Iron & Steel)
•   Excellent Castability
•   Good wear resistance

Nodular Cast Iron Uses:

• Paper Industry machinery
•   IC Engines
•   Power Transmission Equipments
•   Farm Implements & Tractors
•   Earth moving machinery
•  Valves & fittings
• Steel Mill Rolls & Mill equipments
•   Pipes
•  Pumps & Compressors
•  Construction machinery