Special steel brand

There are nearly 2000 special steel grades and about 50000 varieties and specifications in the world. In addition to a wide variety of special steels, they also show different characteristics from ordinary steels in specifications. Besides plates, pipes, wires, strips, bars and special-shaped materials, there are also composite materials, surface alloying materials, surface treatment materials, precision forging materials, precision castings, powder metallurgy products and so on. Summary of steel grade representation methods in China

The brand of steel, referred to as steel number for short, is the name of each specific steel product, and it is a * * * same language for people to understand steel. In China, according to the national standard "Representation of Steel Product Brand" (GB22 1-79), the method of combining Chinese phonetic alphabet, chemical element symbols and Arabic numerals is adopted. Namely: ① Chemical elements in steel grades are represented by international chemical symbols, such as Si, Mn, Cr, etc. The mixed rare earth elements are represented by "re" (or "Xt"). ② The product name, use, smelting and pouring methods are generally expressed by Chinese phonetic abbreviations. ③ The content (%) of main chemical elements in steel is expressed in Arabic numerals. Carbon structural steel ① consists of Q+ number+quality grade symbol+deoxidation method symbol. There is a "Q" in front of the steel grade, which represents the yield point of steel, and the number behind it represents the yield point value, in MPa. For example, Q235 represents a carbon structural steel with a yield point (σs) of 235 MPa.

(2) When necessary, symbols indicating quality grade and deoxidation method can be marked behind the steel grade. The quality grade symbols are a, b, c and d respectively. Deoxidation method symbol: f stands for boiling steel; B stands for semi-killed steel; Z stands for killed steel; TZ stands for special killed steel, which can be unmarked, that is, Z and TZ can be unmarked. For example, Q235-AF stands for Class A boiling steel.

(3) Special-purpose carbon steels such as bridge steel and marine steel are basically represented by carbon structural steel, but the letter indicating the purpose is added at the end of the steel number. High-quality carbon structural steel ① The two digits at the beginning of the steel number indicate the carbon content of the steel, which is expressed as a few ten thousandths of the average carbon content. For example, for steel with an average carbon content of 0.45%, the steel grade is "45", which is not a serial number, so it cannot be read as 45 steel.

(2) High-quality carbon structural steel with high manganese content shall be marked with manganese, for example, 50Mn.

(3) Boiling steel, semi-killed steel and high-quality carbon structural steel for special purposes should be specially marked at the end of the steel grade. For example, the steel grade of semi-killed steel with an average carbon content of 0. 1% is 10b. Carbon tool steel ① The steel grade is marked with "T" to avoid mixing with other steels.

(2) The number in the steel grade indicates the carbon content, which is expressed as a few thousandths of the average carbon content. For example, "T8" means that the average carbon content is 0.8%.

③ If the manganese content is high, mark "Mn" at the end of the steel grade, such as "T8Mn".

④ The phosphorus and sulfur content of high-quality carbon tool steel is lower than that of ordinary high-quality carbon tool steel, and the letter "A" is added after the steel number to indicate the difference, such as "T8MnA". ① Steel grade is marked with "Y" to distinguish it from high-quality carbon structural steel.

② The number after the letter "Y" indicates the carbon content, which is expressed as a few ten thousandths of the average carbon content. For example, the grade of free-cutting steel with an average carbon content of 0.3% is "Y30".

③ For steel grades with high manganese content, the steel grade is also marked with "Mn", such as "Y40Mn". ① The two digits at the beginning of the steel grade indicate the carbon content of the steel, which is expressed as a few ten thousandths of the average carbon content, such as 40Cr.

② The main alloying elements in steel, except a few microalloyed elements, are generally expressed as a few percent. When the average alloy content is

(3) Vanadium V, titanium Ti, aluminum AL, boron B, rare earth re and other alloying elements in steel are all microalloyed elements. Although the content is very low, they should still be indicated in the steel grade. Such as 20MnVB steel. 0.07-0. 12% vanadium and 0.00 1-0.005% boron.

④ High-quality steel should be marked with "A" at the end of the steel grade to distinguish it from ordinary high-quality steel.

(5) Special-purpose alloy structural steel, the steel grade is preceded by (or suffixed with) a symbol representing the purpose of the steel grade. Such as 30CrMnSi steel for riveting screws, the steel number is indicated as ML30CrMnSi. The expression of (1) steel grade is basically the same as that of alloy structural steel.

(2) For professional low-alloy high-strength steel, it shall be marked at the end of the steel grade. For example, 16Mn steel, the steel grade for bridges is "16Mnq", the steel grade for automobile girders is "16MnL" and the steel grade for pressure vessels is "16MnR".

spring steel

According to chemical composition, spring steel can be divided into carbon spring steel and alloy spring steel, and its steel type expression method is basically the same as that of high-quality carbon structural steel, and the latter is basically the same as that of alloy steel.

rolling bearing steel

① There is a letter "G" in front of the steel grade, indicating rolling bearing steel.

② The carbon content of high-carbon chromium bearing steel brand is not marked, and the chromium content is expressed in parts per thousand, such as GCr 15. The steel grade of carburized bearing steel is basically the same as that of alloy structural steel.

Alloy tool steel and high-speed tool steel

① When the average carbon content of alloy tool steel is ≥ 1.0%, the carbon content is not marked; When the average carbon content

② The expression method of alloy element content in steel is basically the same as that of alloy structural steel. However, for alloy tool steel grades with low chromium content, the chromium content is expressed in thousands, and "0" is added before the number indicating the content, which is different from the general method of expressing the element content in percentage. Such as Cr06.

③ The steel grade of high-speed tool steel generally does not represent carbon content, but only represents a few percent of the average content of various alloying elements. For example, the steel grade of tungsten high-speed steel is expressed as "W 18Cr4V". A steel grade with the letter "C" indicates that its carbon content is higher than that of a general steel grade without a crown "C".

Stainless steel and heat-resistant steel

① The carbon content of steel grade is expressed in parts per thousand. For example, the average carbon content of "2Cr 13" steel is 0.2%; If the carbon content in steel is ≤0.03% or ≤0.08%, the steel grade is represented by "00" and "0" respectively, such as 00Cr 17Ni 14Mo2, 0Cr 18 Ni9, etc.

(2) The main alloying elements in steel are expressed in percentage, while titanium, niobium, zirconium, nitrogen, etc. Marking shall be carried out according to the expression method of microalloyed elements in the above alloy structural steel.

Covered electrode steel

Its steel grade is distinguished from other steels by the letter "H" in front of it. For example, stainless steel welding wire is "H2Cr 13", which can be distinguished from stainless steel "2Cr 13".

Silicon steel for electrical purposes

① Steel grade consists of letters and numbers. The letter DR at the beginning of the steel number stands for hot-rolled silicon steel for electrical purposes, DW stands for cold-rolled non-oriented silicon steel for electrical purposes, and DQ stands for cold-rolled oriented silicon steel for electrical purposes.

② The number after the letter represents 100 times of the iron loss value (W/kg).

③ If the letter "G" is added at the end of the steel grade, it means that the inspection frequency is high; If "G" is not added, it means that the test is conducted at a frequency of 50 cycles. For example, the steel grade DW470 shows that the maximum iron loss per unit weight of cold-rolled non-oriented silicon steel products for electrical purposes is 4.7W/kg at 50 Hz frequency.

Pure iron for electrical use

(1) Its brand consists of letters "DT" and numbers, where "DT" stands for pure iron for electrical engineering and numbers stand for serial numbers of different brands, such as DT3.

② Letters added after numbers indicate electromagnetic properties: A- advanced, E- super, C- super, such as DT8A.