1) carbon structural steel
① It consists of Q+ number+quality grade symbol+deoxygenation method symbol. Its steel grade is preceded by "Q", which represents the yield point of steel, and the number behind it represents the yield point value in MPa. For example, Q235 stands for 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 mode symbol: f stands for boiling steel; B stands for semi-killed steel; Z stands for killed steel; TZ stands for special killed steel, and killed steel can be left unmarked, that is, Z and TZ can be left unmarked. For example, Q235-AF stands for Class A boiling steel.
(3) Special-purpose carbon steel, such as bridge steel and marine steel, is basically represented by carbon structural steel, but the letter indicating the purpose is added at the end of the steel number.
2) High quality carbon structural steel
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. For example, the steel with an average carbon content of 0.45% has a steel grade of "45", not a serial number, so it cannot be read as 45 steel.
(2) High-quality carbon structural steel with high manganese content should be marked with manganese, for example, 50Mn.
(3) Boiling steel, semi-killed steel and special-purpose high-quality carbon structural steel shall be specially marked at the end of the steel grade, such as semi-killed steel with an average carbon content of 0. 1%, and the steel grade is 10b.
3) Carbon tool steel
① The steel grade is marked with "T" to avoid confusion with other steel grades.
(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 at the end of the steel number to indicate the difference, such as "T8MnA".
4) Free cutting steel
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 free-cutting steel with an average carbon content of 0.3% has a brand name of "Y30".
③ If the manganese content is high, the steel grade is also marked with "Mn", such as "Y40Mn".
V) alloy structural steel
① The two digits at the beginning of steel grade indicate the carbon content of 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
For example, "12CrMoV" and "12Cr 1MoV" have the same chromium content, which is 0.4-0.7%, the latter is 0.9- 1.2%, and other components are the same. When the average content of alloying elements is ≥ 1.5%, ≥2.5%, ≥ 3.5%, ..., the content should be indicated after the element symbol, which can be expressed as 2, 3, 4, etc. For example 18Cr2Ni4WA.
(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 marked 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) Alloy structural steel for special purposes, the steel grade is preceded by (or suffixed with) a symbol representing the purpose of the steel grade. For example, the steel grade of 30CrMnSi special for riveting screws is marked as ML30CrMnSi.
6) Low alloy high strength steel
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".
7) Spring steel
Spring steel can be divided into carbon spring steel and alloy spring steel according to chemical composition, and its steel number representation method is basically the same as that of high-quality carbon structural steel, and the latter is basically the same as that of alloy structural steel.
8) 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.
9) 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 indicate carbon content, but only indicates 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".
X) 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 is carried out according to the expression method of microalloyed elements in the alloy structural steel.
Xi) 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 used to distinguish stainless steel "2Cr 13".
12) electrical silicon steel
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 (W/kg) of the iron loss value.
(3) The letter "G" at the end of the steel number indicates high-frequency inspection; If "G" is not added, it means that the test is conducted at a frequency of 50 cycles. For example, 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.
13) pure iron for electrician
(1) Its brand consists of letters "DT" and numbers, where "DT" means pure iron for electrician and numbers represent serial numbers of different brands, such as DT3.
② The letters added after the numbers indicate the electromagnetic properties: A- advanced, E- super, C- super, such as DT8A.
Extended data:
Naming rules for steel types:
Steel grades, also known as steel brands, generally use Chinese phonetic alphabet, chemical element symbols and Arabic numerals to indicate the name, purpose, characteristics and technology of steel.
When using the letters of Chinese Pinyin to represent the product name, purpose, characteristics and technological methods, the first letter is usually selected from the Chinese Pinyin that represents the product name.
When it is duplicated with the letter taken by another product, select the second letter or the third letter, or select the first pinyin letter of two Chinese characters at the same time. In principle, only one Chinese phonetic alphabet is used, generally no more than two.
Reference source: Baidu Encyclopedia-Steel Types