Iron (Fe) - Properties, Applications

Topics Covered

Chemical Properties
Physical Properties
Mechanical Properties
Thermal Properties


Iron is a chemical element with Fe as its symbol. It belongs to group 8, periodic number 4 of the periodic table. Its atomic number is 26.

Iron makes up 5% of the Earth's crust and is one of the most abundantly available metals. It is primarily obtained from the minerals hematite and magnetite. It can also be obtained from taconite, limonite, and siderite. Iron is the most used of all the metals.

Iron is also found in meat, potatoes and vegetables and is essential for animals and humans. It is an essential part of hemoglobin.

Iron metal is greyish in appearance, and is very ductile and malleable. It begins to rust in damp air and at elevated temperatures, but not in dry air. It dissolves readily in dilute acids, and is chemically active.

The main mining areas for iron are China, Australia, Brazil, Russia, and Ukraine.

Chemical Properties

The chemical properties of iron are provided in the table below.

Chemical Data
CAS number 7439-89-6
Thermal neutron cross section 2.53 barns/atom
Electrode potential -0.0400 V
Ionic radius 0.640 Å
Electronegativity 1.83
X-ray absorption edge 1.743 Å
Electrochemical equivalent 0.695 g/A/h

Physical Properties

The following table discusses the physical properties of iron.

Properties Metric Imperial
Density 7.87 g/cm3 0.284 lb/in3
Melting point 1536 °C 2797°F
Boiling point 2861 °C 5182°F

Mechanical Properties

The mechanical properties of iron are tabulated below.

Properties Metric Imperial
Tensile strength at break 540 MPa 78300 psi
Yield strength 50 MPa 7250 psi
Poisson’s ratio 0.291 0.291
Modulus of elasticity 200 GPa 29000 ksi
Shear modulus 77.5 GPa 11200 ksi
Hardness, Brinell 146 146
Hardness, Vickers 150 150
Hardness, Rockwell A 49 49
Hardness, Rockwell B 79 79

Thermal Properties

The thermal properties of iron are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@20-100°C/68-212°F) 12.2 µm/m°C 6.78 µin/in°F
Thermal conductivity 76.2 W/mK 529 BTU in/hr.ft².°F


Iron is used in numerous sectors such as electronics, manufacturing, automotive, and construction and building.

The following are the application areas of iron:

  • As the primary constituent of ferrous metals/alloys and steels
  • Alloyed with carbon, nickel, chromium and various other elements to form cast iron or steel
  • In magnets
  • In fabricated metal products
  • In industrial machinery
  • In transportation equipment
  • In instruments
  • In toys and sport goods

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