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 In structural applications, wrought iron has been replaced by steel, which is tougher and stronger.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


Compacted graphite cast iron (also vermicular grain, CG iron or CGI) is an improvement on grey cast iron. It contains blunt, interconnected graphite flakes, whose formation is suppressed by alloys such as titanium (Ti) or magnesium (Mg). This helps to inhibits crack initiation and propagation and so yields a metal with higher tensile strength and ductility than grey iron, coupled with high thermal conductivity than ductile cast iron. It is not so common, but gaining popularity in applications such as engine parts, such as blocks, frames and cylinder liners, train brakes and gear plates.

Grades are designated according to tensile strength, from 250-500 MPa.


Design properties
Cost usd/kg
3-5
Embodied energy MJ/kg
20-50
Carbon footprint kgCO2e/kg
1.5-3
Density kg/m3
7150
Tensile modulus GPa
145
Tensile strength MPa
250-500
Compressive strength MPa
380-440
Hardness Mohs
4.5
Brinell hardness HB
180-225
Poissons ratio
0.26
Thermal conductivity W/mK
39
Temperature min-max °C
-150 to 450
Thermal
conductive
Electrical
conductor