ABNT NBR – ABNT NBR Carbon steel and high-strenght low-alloy steel for strutural use – Requirements. Publication date. which would soon be ruled by several standards, such as the Brazilian NBR , , and and the American ASTM A, A and A with . 12 fev. EN SJ0. JIS G SS ABNT NBR CF ABNT NBR CG ABNT NBR MR NM02 ED VMB
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What made a 7007 carbon steel-based product unique, in terms of corrosion resistance, was the fact that under certain exposure environmental conditions, it could develop on its surface an adherent and protective oxide film, called patina, which acts by reducing the attack speed abbt corrosive agents found in the environment.
Among the steels belonging to this category, the ones in the spotlight are the high-strength and low-alloy steels resistant to atmospheric corrosion. From its launching to the current days, other steels with similar behaviors were developed, which constitute the family of steels known jbr patinable, which would soon be ruled by several standards, such as the Brazilian NBR, and and the American ASTM A, A and A with the purpose of establishing limits to their chemical compositions and mechanical properties.
Steel is produced in a wide variety of types and shapes, each one is capable of efficiently satifying one or more applications. Finally, there are factors associated with the geometry of the component, which explains why different structures of the same steel placed next to each other can suffer different attack levels.
This steel, if hardened and tempered, can reach good tenacity and resistance.
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High-strength and low-alloy steels are used whenever there is the need to: The amount of carbon in the steel defines its classification. Formation of patina can occur following three factors.
Carbon steel have in its composition only limited amounts of chemical elements such as carbon, silicon, manganese, sulfur and phosphorus. The main requirements for the steels intended to structural applications are: Therefore, for example, under continuous wetting conditions determined by poor drying, the formation of patina is severely compromised.
Your content’s indication was send with success. Structural steels may be sorted in three main groups according to the minimum specified flowing stress.
Main alloy elements that contribute to increased resistance against atmospheric corrosion thus favoring the formation of patina are copper and phosphorus. Its major advantage, in addition to dismiss painting in certain environments, is having a mechanical strength higher than carbon steels.
High-strength and low-alloy steels resistant against corrosion are produced in Brazil by Several Steelmakers. This shows a huge evolution in the sector.
Fabio Domingos Pannoni, M. This steel was introduced in the American market in to be specifically applied to the manufacturing of cargo wagons.
ABNT NBR 16264_2016
Chromium, nickel and silicon also exert secondary effects. Such variety results from the continuous nbbr to adequate the product to specific application requirements that appear in the market, either due to the need to control chemical compositions or to assure specific proprieties, which includes the final shape plates, profiles, pipes, bars, etc. The first one is related to the chemical composition of the steel itself. Increase the nb resistance in order to allow an addition of structural unit load or to allow a proportional section decrease, that is, the use of lighter sections; Improve the resistance against atmospheric corrosion; Improve resistance to impact and fatigue limit; Increase the relationship between flowing limit and traction-resistance limit without significant loss of ductility.
Other chemical elements exist only in residual amounts. High carbon steel has more than 0. Low-carbon steels have a maximum of 0. Espessuras entre 20 mm e abaixo.
However, the modern trend of using ever-growing structures has led engineers, designers and builders to use steels with increased resistance, the so-called high-strength and low-alloy steels, with the purpose of avoiding the erection of heavier structures.
Examples include patinable steels immersed in water, buried in the ground or covered by vegetation. In civil construction, the highest interest falls upon the so called structural steels of mid and high-mechanic strength, a term used to designate all steels that due to their resistance, ductility and other properties are appropriate to be used in construction elements subject to loading.
In most of such situations, the corrosion speed of patinable steel is similar to the one of carbon steel. They are more appropriate for mechanic and welding works, not being hardenable, and are used in the construction of buildings, bridges, ships, vehicles, among other uses.
In extremely aggressive environments, such as regions with high levels of sulfur dioxide pollution or those near the shore, painting grants them a performance far superior than carbon steel. Therefore, while the presence of sulfur dioxide, up to certain limits, favors the development of patina, the sodium chloride suspended in maritime atmospheres compromises its protective properties.
Among the currently existing structural steels, the most used and known type is the ASTM A36, which is rated as a medium-mechanical strength carbon steel.
They are commonly used in rails, springs, gears, agricultural components subject to wearing, small tools, etc. Medium-carbon steel has 0. However, it is worth abbnt that phosphorus must be kept as low as possible less than 0. Those steels have been used in the whole world to build bridges, viaducts, silos, power transmission towers, etc.