Steel is a vital material in modern society, used for heavy-duty construction, automotive and consumer goods production, and a wide range of industrial applications. In China, steel is produced in various grades according to Chinese national standards (GB/T). The grades are usually denoted by four-digit numbers, such as GB/T 8162-2008 (structural steel grades) and GB/T 3273-2005 (hot rolled low alloy steel grades). While the numbers may appear intimidating and difficult to understand, they are actually quite easy to decipher.
The first two digits of the GB/T number represent the steel category, with the first digit describing the type and the second the quality grade. For instance, GB/T 8162-2008 is a low-medium carbon steel grade suitable for welding and cold forming; the grade includes various types such as 65, 75 and 85 for carbon steel (65 stands for 0.06% Carbon 0.5% Manganese); and other grades for alloy steel.
The second two digits, in this case “08”, indicate the year or revision, so that in this case the steel grade was first specified in 2008.
Within a quality grade, there may be several types of steel and each type will have its own designation. For example, the 65 type of carbon steel within the GB/T 8162-2008 grade has a designation of 08Mn2 (08 stands for the year of revision, Mn2 stands for Manganese). Each type of steel has its own characteristics and properties.
Beyond the steel grades, there are other specifications to consider when selecting a steel grade, such as the standard associated with the grade, delivery condition, surface treatment, chemical and physical properties, size, packaging and characteristics for heat treatment.
Grade GB/T 4171 Q235NH— Q355NH is a type of weather resistant steel with low carbon content, excellent resistance to atmospheric corrosion, and is typically used in the production of vehicles and machinery exposed to extreme weather or other hazardous environments. It can be used for applications such as bridges, containers, ships and other parts exposed to harsh conditions. The chemical composition of this grade includes elements such as manganese, silicon, titanium, phosphorus, chromium, and vanadium.
The higher the grade of steel, the higher the tensile strength it is likely to possess. Steel grades are usually indicated by numbers, such as 40Cr or 40CrNiMoA, which indicates the percentage of Cr and Ni content respectively. For example, an alloy steel grade such as 40CrNiMoA indicates an alloy containing 40% Chromium, 5% Nickel and 4% Molybdenum.
In conclusion, China produces steel according to different grades as given in the national standard (GB/T). Each steel grade is indicated by four-digit numbers, the first two digits indicating the steel category, the last two indicating the year or revision. Within a grade, there may be several types of steel, with each type having a specific designation. There are also other specifications such as standard, delivery condition, surface treatment, chemical and physical properties, size, packaging and characteristics for heat treatment that need to be considered when selecting a steel grade.
