Here, the use classification of steel materials is used as a basis for the classification of indication methods:
Carbon structural steel
Representation method: Q+ number + (quality level symbol) + (deoxy method symbol) + (dedicated symbol)
1 The steel number is crowned with "Q", which represents the yield point of the steel;
2 The number following "Q" indicates the yield point value in MPa. For example, Q235 indicates that the yield point (σs) is 235
MPa carbon structural steel;
3 If necessary, symbols indicating the quality level and deoxidation method may be marked after the steel number. The quality grade symbols are A, B, C, and D, respectively.
Deoxidation method symbol: F for boiling steel; b for semi-static steel: Z for killed steel; TZ for special killed steel, killed steel may not be a symbol, that is, Z and TZ can not mark. For example, Q235-AF indicates Grade A boiling steel.
Special purpose carbon steels: For example, bridge steels, shipboard steels, etc. Basically, carbon structural steels are used, but the steel letters are added to the end of the steel.
2. High-quality carbon structural steel
Representation method: number + (element symbol) + (deoxy method symbol) + (dedicated symbol)
The two digits at the beginning of a steel number indicate the carbon content of the steel, expressed in parts per million of the average carbon content. For example, steel with an average carbon content of 0.45% and a steel number of “45” is not a sequential number, so it cannot be read as 45 steel.
2 High-quality carbon structural steel with high manganese content should be marked with manganese, such as 50Mn.
3 Boiling steel, semi-killed steel and special-purpose high-quality carbon structural steels shall be specially marked at the end of the steel grade. For example, semi-static steel with an average carbon content of 0.1% shall be 10b.
3. Carbon tool steel
Representation method: letter T + number + (element symbol) + (quality level symbol)
1 The steel is crowned with "T" to avoid mixing with other steels.
The number in the 2 steel indicates the carbon content, expressed as a few thousandth of the average carbon content. For example "T8" means that the average carbon content is 0.8%.
3 If the manganese content is higher, “Mn” is marked at the end of the steel number, such as “T8Mn”.
4 The phosphorus and sulfur content of the high-quality high-quality carbon tool steel is lower than that of ordinary high-quality carbon tool steel. The letter “A” is added at the end of the steel number to indicate the difference, such as “T8MnA”.
4. Cutting steel
Representation method: letter Y + number + (element symbol)
1 The steel is crowned with "Y" to distinguish it from high-quality carbon structural steel.
The number after the 2 letter "Y" indicates the carbon content, expressed in parts per million of the average carbon content, for example free cutting steel with an average carbon content of 0.3%, whose steel number is "Y30".
3 If the manganese content is higher, “Mn” is also marked after the steel number, for example “Y40Mn”.
5. Alloy structural steel
Representation: (Professional Symbols) + Numbers + Major Alloy Elements Symbols and Numbers + Trace Alloy Element Symbols + (Quality Grade Symbols) + (Professional Symbols)
The two digits at the beginning of a steel number indicate the carbon content of the steel, expressed as a fraction of the average carbon content, such as 40Cr.
2 The major alloying elements in steel, except for individual microalloying elements, are generally expressed in percent. When the average alloy content is less than 1.5%, only the symbol of the element is generally marked in the steel number, but the content is not marked, but in special circumstances, it is easy to cause confusion. After the element symbol, the number “1” may also be marked, for example, the steel number. "12CrMoV" and "12Cr1MoV", the former chromium content of 0.4-0.6%, the latter is 0.9-1.2%, the remaining components are the same. When the average content of alloying elements is ≥ 1.5%, ≥ 2.5%, ≥ 3.5%, etc., the content should be indicated after the element symbol, which can be expressed as 2, 3, 4...etc. For example 18Cr2Ni4WA.
3 Alloy elements such as vanadium V, titanium Ti, aluminum AL, boron B, rare earth RE, etc. in steel are microalloying elements. Although the content is very low, they should be marked in the steel number. For example, in 20MnVB steel: vanadium is 0.07-0.12%, boron is 0.001-0.005%.
4 High-quality steel should be added "A" at the end of the steel to distinguish it from ordinary high-grade steel.
5 special purpose alloy structural steel, steel crown (or suffix) represents the symbol of the steel use. For example, special 30CrMnSi steel for rivets, the steel number is ML30CrMnSi
6. Low alloy high strength steel
Representation: (Professional Symbols) + Numbers + Major Alloy Elements Symbols and Numbers + Trace Alloy Element Symbols + (Quality Grade Symbols) + (Professional Symbols)
Steel No. 1 is basically the same as the alloy structural steel.
2 For the professional use of low-alloy high-strength steel, should be marked at the end of the steel number. For example, for 16Mn steel, special steel grades for bridges are “16Mnq”, special grades for automobile girders are “16MnL”, and special steel grades for pressure vessels are “16MnR”.
7. Spring steel
Spring steel can be divided into two types according to the chemical composition of carbon spring steel and alloy spring steel. The steel number expresses the method. The former is basically the same as the high-quality carbon structural steel, and the latter is basically the same as the alloy structural steel.
8. Rolling bearing steel
display method:
High carbon chromium bearing steel: letter G+Cr element symbols and numbers
Carburizing bearing steel: letter G + number + major alloy element symbol and number + trace alloy element symbol + (quality grade symbol)
1 The steel crown is marked with the letter “G”, which indicates rolling bearing steel.
2 Carbon content of high carbon chromium bearing steel grades is not marked, chromium content is expressed in parts per thousand such as GCr15. Carburized bearing steel steel representation method is basically the same as alloy structural steel.
9. Alloy tool steel and high speed tool steel
1 When the average carbon content of the alloy tool steel grade is ≥ 1.0%, the carbon content is not marked; when the average carbon content is <1.0%, it is expressed in parts per thousand. For example, Cr12, CrWMn, 9SiCr, 3Cr2W8V.
2 The expression of alloying elements in steel is basically the same as that of alloy structural steels. However, for alloy steels with lower chromium content, the chromium content is expressed in parts per thousand, and “0” is added before the figure indicating the content, so that it is expressed as a percentage of the general element content. Differentiate. For example Cr06.
3 The steel number of high-speed tool steel is generally not marked with carbon content, only a few percent of the average content of various alloy elements. For example, the steel grade of tungsten high speed steel is expressed as "W18Cr4V". Steel grades with the letter "C" indicate that their carbon content is higher than that of the unbranded "C."
10. Stainless steel and heat-resistant steel
Carbon content in steel No. 1 is expressed in parts per thousand. For example, the average carbon content of “2Cr13” steel is 0.2%. If the carbon content in steel is ≤0.03% or ≤0.08%, the steel number is preceded by “00” and "0", for example 00Cr17Ni14Mo2, 0Cr18.
Ni9 and so on.
2 The major alloying elements in the steel are expressed in percent, while titanium, niobium, zirconium, nitrogen, etc. are marked according to the above-mentioned method of expressing the alloying steel to the microalloying elements.
11. Welding rod steel
Its steel number is preceded by the letter "H" to distinguish it from other steels. For example, stainless steel wire is "H2Cr13", which can be distinguished from stainless steel "2Cr13".
12. Silicon steel for electricians
1 The steel number consists of letters and numbers. The steel head letter DR indicates hot-rolled silicon steel for electricians, DW indicates cold-rolled non-oriented silicon steel for electricians, and DQ indicates cold-rolled grain-oriented silicon steel for electricians.
The number after 2 letters represents 100 times the iron loss value (W/kg).
3 The letter “G” at the end of the steel number indicates that it is tested at a high frequency; if it is not “G”, it is tested at a frequency of 50 cycles.
For example, steel number DW470 indicates that the maximum unit weight iron loss value of the cold-rolled non-oriented silicon steel products for electrical appliances at a frequency of 50 Hz is 4.7 W/kg.
13. Electric iron
1 Its brand name consists of the letters “DT” and numbers. “DT” indicates pure iron for electricians, and numbers indicate the serial numbers of different brands, such as DT3.
2 The letters added after the numbers indicate the electromagnetic properties: A - Advanced, E - Special, C - Super, such as DT8A.