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.
The Sendzimir process is a special hot-dip galvanising technique used to coat steel sheets or strips directly inside the steelworks during their production phase. It takes its name from its inventor, Tadeusz Sendzimir.
This method involves immersing the sheet metal in a special ceramic tank containing molten zinc. To improve the properties of the bath and promote better adhesion of the metal coating, lead is usually added to help make the metal more fluid, and aluminium to facilitate the zinc’s adhesion to the steel surface.
Before being immersed in zinc, however, the sheet metal must be properly prepared. It is then thoroughly degreased to remove any residues and impurities, followed by treatment with hydrochloric acid (pickling) to remove iron oxides from the surface.
The thickness of the zinc layer that forms on the steel strip is adjusted according to the speed at which the strip passes through the bath: the higher the speed, the thinner the coating. This parameter is precisely controlled by a system of air blades that modulate the amount of zinc deposited.
Once galvanising is complete, the strip is rewound and ready for the next stages of processing, such as profiling.
The main source of the description
Material-Archiv. (2024). Baustahl, unlegiert.
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