The grade and finish of steel you require will depend on how you intend to use your components. Structural steel is widely used in construction, because it is easy to weld, both to itself and to other types of steel and compared to harder steels, it can be easily machined.
Structural steel has to meet industry standards for dimensional tolerances and composition. The properties of structural steel result from both its chemical composition and its method of manufacture.
CHEMICAL COMPOSITION OF S275 AND S355 STRUCTURAL STEELS
The main chemical components of structural steel include iron, carbon, and manganese, other additives include phosphorus, silicon, chromium vanadium and Tungsten. After iron, carbon is the most important element in structural steel which is why they are sometimes called carbon steels. The presence of carbon in steel makes it stronger and reduces the ductility, but lower carbon content makes it easier to weld. Finding the perfect balance is key when choosing the correct material for your purpose.
Manganese is one of the most common additives in structural steel after iron and carbon. It is essential for good machinability and it helps to avoid cracking and splitting during the rolling process. Small amounts of phosphorus improves machinability and increases the tensile strength, but too much makes it brittle. Sulphur is mostly regarded as an impurity, it can adversely affect the properties of structural steel.