Non-alloy structural steels are iron-based materials with a low carbon content. Thanks to their low cost and good mechanical properties, they are widely used, especially in the steel and mechanical engineering industries. These types of steel account for over 90% of the sector’s total production, demonstrating their industrial importance.
They are commonly sold in the form of bars or profiles, obtained by hot rolling or cold drawing. In terms of properties, they are ductile, easy to work with, flexible and strong. However, they cannot be hardened. Interestingly, as the carbon content increases, so do the hardness and strength of the material.
Thanks to their low cost and characteristics that are more than adequate for numerous applications, non-alloy steels are often used in the manufacture of components for machinery and metal structures, provided that no special heat treatments are required. These are simple materials, but nevertheless reliable for many common uses.
Steel is made from cast iron, an alloy containing up to 4% carbon along with other unwanted or excess elements such as silicon, manganese, sulphur and phosphorus. Cast iron is transformed into steel through a process called “refining”, during which the carbon content is reduced and impurities are almost completely eliminated. This process is followed by further treatment to improve the final quality of the material.
At the end of its life, steel is recovered, sorted by type, remelted and reused to create new products. Finally, it should be remembered that non-alloy construction steel is subject to corrosion (rust) and has a rather limited heat resistance.
Galvanising is the process by which a zinc coating is applied to a metal product, usually steel, to protect it from galvanic corrosion.
Zinc is less electronegative (i.e. less noble) than steel, so if the protective film breaks or becomes porous, it itself becomes the sacrificial anode in electrolytic corrosion and is consumed if the field lines are closed.
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