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Steel is a versatile, popular material used in the construction of everything from skyscrapers to housing. Steel beams are composed mostly of iron with some alloying elements. Two types of steel beams exist: cast iron and wrought iron beams. Cast iron beams are made by pouring molten iron into a mold and are strong in compression but brittle. Wrought iron beams are made by forming heated iron and are strong in tension.
Strength
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Steel has a very high strength-to-weight ratio. This means that a steel beam of a given mass is capable of resisting much higher stresses without fracture than an equivalent mass of wood or stone.
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Resistance to Corrosion
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Steel can be manufactured in such a way as to be extremely resistant to rust and corrosion. Stainless steel is a mix of steel and chromium. Unlike wood, steel does not rot. Steel beams thus have a much longer life expectancy.
Cost
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Steel costs very little compared with other metals like aluminum or titanium. This, combined with its other mechanical and chemical attributes, contributes significantly to the popularity of steel beams as a construction material.