The material. The foundations of modern industrial society are set, so to speak, in cast iron: it is the material that made the Industrial Revolution possible. Today it holds a second honor: that of being the cheapest of all engineering metals. Cast iron contains at least 2% carbon; most have 3-4%—and from 1-3% silicon. The carbon makes the iron very fluid when molten, allowing it to be cast to intricate shapes. There are five classes of cast iron: gray, white, ductile (or nodular), malleable, and alloy. The two that are most used are gray and ductile. This record is for ductile cast iron.
Composition
Fe/3.2-4.1% C/1.8-2.8% Si/ < 0.8% Mn/ <0.1% P/ <0.03% S
|
General properties |
|
|
Density |
7050 – 7250 kg/m3 |
|
Price |
*0.7 – 0.8 USD/kg |
|
Mechanical properties Young’s modulus |
165 |
– 180 |
GPa |
|
Yield strength (elastic limit) |
250 |
– 680 |
MPa |
|
Tensile strength |
410 |
– 830 |
MPa |
|
Elongation |
3 |
– 18 |
% |
|
Hardness—Vickers |
115 |
– 320 |
HV |
|
Fatigue strength at 107 cycles |
180 |
– 330 |
MPa |
|
Fracture toughness |
22 |
– 54 |
MPa. m1/2 |
|
Thermal properties |
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|
Melting point |
1130 – |
1250 |
°C |
|
Maximum service temperature |
350 – |
7450 |
°C |
|
Thermal conductor or insulator? |
Good conductor |
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|
Thermal conductivity |
29 – |
44 |
W/m. K |
|
Specific heat capacity |
460 – |
495 |
J/kg. K |
|
Thermal expansion coefficient |
10 – |
12.5 |
p, strain/°C |
|
Electrical properties |
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Electrical conductor or insulator? |
Good conductor |
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|
Electrical resistivity |
49 – |
56 |
pnhm. cm |
Ductile or malleable cast irons are used for heavily loaded parts such as gears and automotive suspension components.
Ecoproperties: material
|
Annual world production |
1.1 X 109 |
– 1.2 X 109 tonne/yr |
|
|
Reserves |
78 X 109 |
– 79 X 109 |
tonne |
|
Embodied energy, primary production |
16 |
– 18 |
MJ/kg |
|
CO2 footprint, primary production |
1.0 |
– 1.1 |
kg/kg |
|
Water usage |
*13 |
– 39 |
l/kg |
|
Eco-indicator |
38 |
– 42 |
millipoints/kg |
|
Ecoproperties: processing |
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|
Casting energy |
*3.2 |
– 3.7 |
MJ/kg |
|
Casting CO2 footprint |
*0.19 |
– 0.22 |
kg/kg |
|
Deformation processing energy |
*2.5 |
– 3.1 |
MJ/kg |
|
Deformation processing CO2 footprint |
*0.2 |
– 0.24 |
kg/kg |
|
Recycling |
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|
Embodied energy, recycling |
4.9 |
– 5.5 |
MJ/kg |
|
CO2 footprint, recycling |
0.29 |
– 0.32 |
kg/kg |
|
Recycle fraction in current supply |
60 |
– 80 |
% |
Typical uses. Brake discs and drums; bearings; camshafts; cylinder liners; piston rings; machine tool structural parts; engine blocks, gears, crankshafts; heavy-duty gear cases; pipe joints; pump casings; components in rock crushers.
