The total world steel production is about 1350 million tons per year (2008). Where does all this steel go?
Six sectors of steel consumption
Below are six sectors of industry and construction, which consume the vast majority of global steel production. These six sectors of consumption steel in total world consumption are as follows (picture):
- Construction (50 %)
- Mechanical engineering (14 %)
- Hardware (14 %)
- Transport (15 %)
- Appliances (3 %)
- Electrical equipment (3 %)
Picture – End steel products
Steel in construction (50 %)
Steel profiles (20 %)
The peculiarity of I-beams is, that in the plane of the wall they carry well the load as a bending moment, so cutting force. Steel I-beams are produced by hot rolling, as well as by welding from individual steel sheets. I-beam wall resists shear forces, and the shelves to bending moments.
Important general design requirements:
- shear strength in the plane of the wall;
- stiffness in the plane of the wall;
- corrosion resistance;
- the cost.
Hollow steel profiles (4 %)
Hollow steel profiles are made from ordinary carbon steel. They usually have a square (less often round) transverse section. The corners of square profiles have large rounding angles. Hollow steel pipes are made from flat sheets by flexible and subsequent welding.
I-beams are very effective in bearing loads in the plane of the wall. However, I-beams have low resistance to lateral forces and bending moments., and also have low torsional stability. Symmetrical hollow steel profiles effectively resist multiaxial loads and provide high torsional resistance.
Sometimes hollow steel profiles are filled with concrete. This increases their compressive strength and provides fire resistance for at least 60 minutes.
Important design requirements:
- multi-axis strength;
- multi-axis stiffness
- corrosion resistance;
- the cost
- fire protection (for filled with concrete).
Armature (10 %)
Reinforcing bars - reinforcing rods - are installed in concrete (often in the form of a rigid frame) to increase the tensile and flexural strength of concrete components. This procedure is called reinforcement.. Reinforcement can be prestressed, to induce compressive stresses in concrete. This prevents the formation of cracks in concrete at a certain level of tensile stresses..
Typically, the rebar is made from hardened and tempered structural steel without a protective coating..
Concrete provides steel reinforcement with an alkaline environment, which prevents their corrosion. If there is not enough concrete around the rebar, then this can lead to an increase in its rusting, crack growth and, eventually, destruction.
Important properties for reinforcement are:
- good bonding to concrete (to transfer efforts);
- high tensile strength;
- temperature coefficient of expansion comparable to that, what's the concrete;
- the cost.
Steel frames for false ceilings (4 %)
Frames for suspended ceilings are a common design for non-residential buildings.. They are a lattice of steel T-shaped profiles with the letter T "upside down". Then non-metallic panels are installed in the spaces between these profiles.. False ceilings hide everything, what is above them (their fastening system, ventilation ducts), and also create a favorable acoustic balance in the room. These ceilings provide easy access to systems when required, which are located above for their maintenance and repair. The disadvantage of these ceilings is that, that they reduce the usable height of the room.
Steel roof (2 %)
- the cost;
- aesthetic properties.
Obreshetina (1 %)
Purlins are horizontal structural elements, which are usually used for roofing. They support the roof and are installed on building walls and steel beams.
Steel window and door lintels (1 %)
Lintels are horizontal steel beams, which are usually installed over the openings of doors and windows, as well as foci.
Steel in mechanical engineering (14 %)
Mechanical engineering encompasses a wide range of industrial equipment from conventional lathes to huge rolling mills.. for instance, there are not so many rolling mills, but each one requires a huge amount of steel to make.
for instance, the mill for the production of sheet metal is a very large, complex and large complex of machines, which has a service life of more 50 years. A typical plate mill rolls steel or aluminum billets up to five meters wide with up to 10000 tons and uses rolling stands with a drive with a capacity of up to 10 megawatt, which are installed on a steel base weighing 500 tons. Typical rolling production equipment 2 million steel sheets per year can extend a distance 1,5 kilometers, weigh about 25000 tons and cost about 150 million dollars.
Plate rolling mills are usually discontinued due to reduced profitability, and not due to mechanical failures or malfunctions. "Old" rolling mills are usually modernized and sent to other countries, where such production is still profitable.
Steel products (14 %)
Steel products include a wide range of steel products from steel beer cans to steel shipping containers..
Steel in transport (15 %)
Cars (12 %)
Steel makes 60 % typical passenger car. Traditionally, cast engine blocks are made of cast iron, but increasingly replaced by aluminum alloys. Steel has strength and rigidity, which provides the car with reliability and safety. In recent years, there has been serious competition for steel from aluminum alloys., which offers a reduction in unit weight compared to traditional steels and cast irons.
but, the emergence of special high-strength steels and new methods of welding them make it possible for steel to compete with aluminum.
Other modes of transport (3 %)
The production of steel rails for railways consumes about 1 % world steel production. Rails are made from hot-rolled medium carbon steel. The high carbon content in steel contributes to the brittle fracture of rails under the influence of high operating stresses. Rails made of medium carbon - fairly soft - steels are prone to rapid wear and require frequent replacement.
Railway wheels also made from medium carbon steels. They also wear out and need to be replaced over time..
Steel in household appliances (3 %)
The following household machines are considered the largest consumers of steel in household appliances (in brackets - typical steel content in kilograms):
- Washer (65);
- electric stove (56);
- clothes dryer (39);
- fridge (38);
- freezer (45);
- microwave (19)
Steel provides strength to the hull, in which electrical components and thermal insulation are installed.
Electrical equipment (3 %)
Electrical steels are important magnetic materials and play a large role in the generation and distribution of electrical current.:
- Grain-oriented steel provides low power loss for high efficiency transformers;
- Non-oriented grain steel has similar magnetic properties in all directions and is used in generators, small transformers and many electrical appliances.
Many electrical cables are insulated conductors with an outer steel jacket, solid or braided. Besides, steel is widely used to make steel conduits for electrical wiring and electrical junction boxes.