Iron

1.3-30 usd/kg
Circularity potential
High
Strength
Very high
Production energy
High
Stiffness
High
Embodied CO2
Medium
Density
Extreme

Iron is a valuable modern engineering material that, in the past, played an import role in the development of architecture and industry. Wrought iron, which is now largely only used for decorative purposes, allowed for longer uninterrupted structures in architecture, as well as elegant detailing that was not practical with other materials of the time. In structural applications, wrought iron has been replaced by steel, which is tougher and stronger.

Cast iron, on the other hand, offers many advantages over steel and other metals when it comes to endurance and dampening, especially in complex castings and large structural components. These three metals are primarily distinguished by their carbon content. Wrought iron contains almost no carbon (<0.035%), cast iron between 2-4% and steel between 0.06-2%. Alloys are mixed with cast iron and steel to further enhance mechanical properties and corrosion resistance. And this opens up opportunities for heat treatment to refine strength and hardness.


Sustainability concerns
Non-renewable ingredients
Raw material generates polluting by-products


Malleable cast iron have good mechanical strength coupled with toughness and machinability. They are good for components that are required to have some ductility or malleability in application. It is produced from white cast iron, through a process of heat treatment. The iron carbides that make white cast iron so hard and brittle, breakdown into iron and carbon to produce a low-carbon iron matrix with carbon nodules (sometimes also referred to as malleable steel). The free graphite and porous surface give these metals good sliding and abrasion resistant properties.

It is used to make pipe fittings, valves, electrical fittings and hand tools. Heavy duty applications include bearings, chains, sprockets, drive train and axel components, and for parts of train undercarriage and farm machinery.

The heat treatment process determines the microcrystalline structure of the iron matrix and whether it is whiteheart (W), ferritic blackheart (B) or pearlitic (P). The grades are further differentiated by tensile strength and elongation.

Whiteheart malleable cast iron with pearlite core and ferrite surface:
≥ 350 MPa tensile and 4% elongation, 350/4 or W35-04
≥ 380 MPa tensile and 12% elongation, 380/12 or W38-12
≥ 400 MPa tensile and 5% elongation, 400/5 or W40-05
≥ 450 MPa tensile and 7% elongation, 450/7 or W45-07

Blackheart malleable cast iron with ferrite matrix:
≥ 300 MPa tensile and 6% elongation, 300/6 or B30-06
≥ 320 MPa tensile and 12% elongation, 320/12 or B32-12
≥ 350 MPa tensile and 10% elongation, 350/10 or B35-10

Pearlitic malleable cast iron:
≥ 450 MPa tensile and 6% elongation, 450/6 or P45-06
≥ 500 MPa tensile and 5% elongation, 500/5 or P50-05
≥ 550 MPa tensile and 4% elongation, 550/4 or P55-04
≥ 600 MPa tensile and 3% elongation, 600/3 or P60-03
≥ 650 MPa senile and 2% elongation, 650/2 or P65-02
≥ 700 MPa tensile and 2% elongation, 700/2 or P70-02
≥ 800 MPa tensile and 1% elongation, 800/1 or P80-01


Design properties
Cost usd/kg
3-6
Embodied energy MJ/kg
20-50
Carbon footprint kgCO2e/kg
1.5-3
Density kg/m3
7150
Tensile modulus GPa
172-179
Tensile strength MPa
340-480
Hardness Mohs
5
Brinell hardness HB
220-230
Thermal expansion (µm/m)/ºC
12
Melt temperature ºC
1376
Thermal conductivity W/mK
40
Temperature min-max °C
-150 to 450
Thermal
conductive
Electrical
conductor