Representation method of steel grade in China (II): Carbon structural steel and low alloy high strength structural steel

Carbon structural steel and low-alloy high-strength structural steel are usually divided into general steel and special steel.

The brand representation method is composed of the Chinese phonetic alphabet of the yield point or yield strength of the steel, the value of the yield point or yield strength, the quality grade of the steel, and the deoxidation degree of the steel, which is actually composed of four parts.

① The Pinyin letter “Q” representing the yield point is used for general structural steel. The yield point value (unit: MPa), quality grade (a, B, C, D, e), deoxidation method (F, B, Z, TZ) and other symbols specified in Table 1 form the brand in sequence

For example, the grades of carbon structural steel are: q235af, q235bz; The grades of low alloy high strength structural steel are: Q345C, Q345D.

Q235bz refers to killed carbon structural steel with yield point ≥ 235mpa and quality grade B.

Q235 and Q345 are the most typical, most widely used and widely used grades of engineering steel. These two brands are available in almost all countries in the world.

In the brand composition of carbon structural steel, the symbol “Z” of killed steel and the symbol “TZ” of special killed steel can be omitted. For example, the brand representation of Q235 steel with quality grade C and D respectively should be q235cz and q235dtz, but Q235C and q235d can be omitted.

Low alloy high strength structural steel includes killed steel and special killed steel, but the symbol indicating deoxidation method is not added at the end of the brand.

② . special structural steel is generally represented by the symbol “Q” representing the steel yield point, the yield point value and the symbol representing the product purpose specified in Table 1. For example, the steel brand for pressure vessel is represented as “Q345R”; The grade of weathering steel is q340nh; Steel grade for q295hp welded gas cylinder; Q390g boiler steel; Q420q steel grade for bridge.

③ If necessary, the grade of general low-alloy high-strength structural steel can also be expressed in order by two Arabic numerals (indicating the average carbon content, in tens of thousands) and chemical element symbols; The grade of special low-alloy high-strength structural steel can also be expressed in order by two Arabic numerals (indicating the average carbon content, in tens of thousands) and chemical element symbols, as well as some specified symbols representing the purpose of the product.