3.3 Steel

Global production of steel is currently about 1000 million tonnes per year. Its high strength in compression and tension, high stiffness, and ductility make it a versatile and extremely useful material for an engineer, which is why steel is an integral part of many products.

Table 3.3.1 Worldwide Usage of Steel

Category	Example of application	Worldwide usage	Millions of tonnes per year (Mt)
Transport
Cars and light trucks	Engine block, chassis, doors	9%	93
Trucks and ships	As above	3%	28
Industrial Equipment
Electrical Equipment	Pylons, motors, transformers	3%	27
Mechanical Equipment	Bearings, factory machinery	13%	137
Construction
Infrastructure	Train rails, gas pipes	14%	150
Buildings	Reinforcement bar for concrete, “I” bars, structural frame	42%	433
Metal Products
Metal Goods	Furniture, filing cabinets, cutlery	12%	134
Consumer Packaging	Tinned goods, aerosols	1%	9
Domestic Appliances	Fridges, washing machines	3%	29

(Source: Sustainable Materials With Both Eyes Open [see reference 2])
Figure 3.3.1 sourced with permission from Sustainable Materials With Both Eyes Open. This book is available free to view online
http://withbotheyesopen.com/index.html

The majority of steel is used as reinforcing bar in the construction industry, when it is coupled with concrete to make a successful combination to build cheap, strong and quick buildings and infrastructure. These are ideal conditions for developers looking to reduce costs and make profit quickly. The other uses are varied, from electricity pylons to stainless steel spoons.

Producing steel involves mining iron ore and heating it to a very high temperature (1000^oC). The mining requires huge amounts of energy, as does the heating of the ore. All this energy contributes to steel's “embodied energy”, a concept that will be explored when looking at the impacts of material production. The important part at this point is to grasp the scale of steel use worldwide – look outside and see what you can find that incorporates steel in the design. Multiply that by the number of streets, towns, cities, countries and continents in the world...

There some are environmental advantages of steel, one being the fact that it is highly recycled and can continue to be recycled indefinitely (although it loses its quality in each cycle). It is also durable if protected from corrosion, and can be salvaged for reuse, in some cases by up to 95%.