Spain produces structural steel according to the European standard EN 10025, which includes a number of structural steel grades, such as S235, S275, S355, and more. Structural steel grades all share a common designations system, based upon the EN 10025 standard.
The S275, S355 and S420 structural steel grades all share the same designation, with each number indicating the minimum yield strength in N/mm2 (for example, S355 has a minimum tensile strength of 355 N/mm2). For example, S275 has a yield strength of at least 275 N/mm2.
Steel grades are also classified according to their chemical composition. The steels can be considered as carbon steels, low alloy steels, and high alloy steels. EN 10025 standard defines many of the most common alloy steels classes and designations, including S235, S275, S355, and S420.
S235 is an unalloyed carbon steel grade. It has a minimum yield strength of 235 N/mm2. S275 is a low carbon, high tensile strength structural steel with a minimum yield strength of 275 N/mm2. It offers good weldability and can be used in the fabrication of structures and machines.
S355 is a high strength, low alloy, manganese-containing structural steel. It has a minimum yield strength of 355 N/mm2 and good weldability. It is a formable and highly versatile structural steel that can be used for a range of applications.
S420 is a low alloy steel grade. It has a minimum yield strength of 420 N/mm2, and can be used in applications where elevated temperatures are encountered. It is also used in high strength applications and is resistant to corrosion.
Steel grades are also classified according to their manufacturing processes. There are hot rolled steels, and cold rolled steels. Hot rolled steel is manufactured in large, hot-rolled and cold-rolled sections, while cold rolled steel is manufactured in much smaller sections.
Hot rolled steel is produced through a process of hot rolling, which is carried out at high temperatures. It is then cooled, cut and formed into a variety of shapes. It is used mainly for forming structural members in buildings, bridges, and other constructions, as well as for various piping and tubing applications.
Cold rolled steel is produced through a process of cold rolling, which is carried out at low temperatures. This process is used mainly for producing sheet, strip and coil material, which is then used for the production of various industrial products, such as appliances, packaging materials and electronics components.
Steel grades are also classified according to their mechanical properties. The grades are divided into different classes, such as Normalized, Annealed, Tempered, Quenched and Tempered, Quenched and Tempered and Without Thermal Treatment. For example, Normalized steel has improved ductility, strength and dimensional accuracy, while Annealed steel has improved formability, ductility, and strength. Tempered steel has improved strength, toughness and wear resistance, while Quenched and Tempered steel has improved ductility, strength and wear resistance.
Steel is also classified according to its surface treatment. Common treatments include Galvanizing, Zinc-Coating, and Painting. Galvanizing is a process of coating steel with zinc, to enhance its corrosion resistance. Zinc-Coating is a process of coating steel with zinc-alloy based material, to improve its corrosion resistance. Painting is a process of coating steel with paint, to improve its appearance.
