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In our country, the use classification of steel is used as the basis for the classification of the representation method. SGS / TUV factory cnc machining parts CNC metal cutting service
1 carbon structural steel
Representation method: Q + number + (quality grade symbol) + (deoxidation method symbol) + (special purpose symbol)①The steel grade is prefixed with “Q”, which represents the yield point of the steel;
②The number after “Q” indicates the value of the yield point, and the unit is MPa. For example, Q235 means carbon structural steel with a yield point (σs) of 235MPa;
③If necessary, the symbol indicating the quality level and deoxidation method can be marked behind the steel number. The quality grade symbols are A, B, C, D respectively.
Deoxidation method symbol: F means boiling steel; b means semi-killed steel; Z means killed steel; TZ means special killed steel, and killed steel can be free from symbols, that is, both Z and TZ can be omitted. For example, Q235-AF means Grade A boiling steel. SGS / TUV factory cnc machining parts CNC metal cutting service
Carbon steel for special purposes: such as bridge steel, marine steel, etc., basically use the expression method of carbon structural steel, but add the letter indicating the purpose at the end of the steel number.
2 High-quality carbon structural steel
Representation method: number + (element symbol) + (deoxidation method symbol) + (special purpose symbol)① The two digits at the beginning of the steel number indicate the carbon content of the steel, expressed in ten-thousandths of the average carbon content. For example, for steel with an average carbon content of 0.45%, the steel number is “45”. It is not a serial number, so it cannot be read as 45 gauge steel.
② For high-quality carbon structural steel with high manganese content, the manganese element should be marked, such as 50Mn.
③The boiling steel, semi-killed steel and special-purpose high-quality carbon structural steel should be marked at the end of the steel number. For example, the steel number of semi-killed steel with an average carbon content of 0.1% is 10b. SGS / TUV factory cnc machining parts CNC metal cutting service
3 carbon tool steel
Representation method: letter T + number + (element symbol) + (quality grade symbol)
①The steel number is prefixed with “T” to avoid mixing with other steel types.
②The number in the steel number indicates the carbon content, expressed in thousandths of the average carbon content. For example, “T8” means that the average carbon content is 0.8%.
③ For those with higher manganese content, “Mn” is marked at the end of the steel number, such as “T8Mn”.
④The phosphorus and sulfur content of high-grade high-quality carbon tool steel is lower than that of general high-quality carbon tool steel. The letter “A” is added at the end of the steel number to show the difference, such as “T8MnA”. SGS / TUV factory cnc machining parts CNC metal cutting service
4 free cutting steel
Representation method: letter Y+number+(element symbol)
①The steel number is crowned with “Y” to distinguish it from high-quality carbon structural steel.
②The number after the letter “Y” indicates the carbon content, expressed in ten-thousandths of the average carbon content. For example, the free-cutting steel with an average carbon content of 0.3% has a steel grade of “Y30”.
③ For those with higher manganese content, “Mn” is also marked after the steel number, such as “Y40Mn”.
5 alloy structural steel
Representation method: (special-purpose symbol) + number + main alloy element symbol and number + trace alloy element symbol + (quality grade symbol) + (special-purpose symbol)
① The two digits at the beginning of the steel number indicate the carbon content of the steel, expressed in ten-thousandths of the average carbon content, such as 40Cr. SGS / TUV factory cnc machining parts CNC metal cutting service
②The main alloying elements in steel, except for a few microalloying elements, are generally expressed in a few percent. When the average alloy content is less than 1.5%, generally only the element symbol is marked in the steel number, but not the content. However, if it is easy to cause confusion under special circumstances, the number “1” can also be marked after the element symbol, such as steel number “12CrMoV” and “12Cr1MoV”, the chromium content of the former is 0.4-0.6%, the latter is 0.9-1.2%, and the rest of the ingredients are all 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. accordingly. For example 18Cr2Ni4WA.
③Alloying elements such as vanadium V, titanium Ti, aluminum AL, boron B, and rare earth RE in steel are microalloying elements. Although the content is very low, they should still 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-grade high-quality steel should add “A” at the end of the steel number to distinguish it from general high-quality steel.
⑤ For alloy structural steels for special purposes, the steel number is prefixed (or suffixed) with a symbol representing the use of the steel type. For example, the 30CrMnSi steel specially used for riveting screws, the steel number is expressed as ML30CrMnSi. SGS / TUV factory cnc machining parts CNC metal cutting service
6 low alloy high strength steel
Representation method: (special-purpose symbol) + number + main alloy element symbol and number + trace alloy element symbol + (quality grade symbol) + (special-purpose symbol)
①The expression method of steel grade is basically the same as that of alloy structural steel.
② For low-alloy high-strength steel for professional use, it should be marked at the end of the steel number. For example, 16Mn steel, the special steel grade used for bridges is “16Mnq”, the special steel grade for automobile beams is “16MnL”, and the special steel grade for pressure vessels is “16MnR”.
7 spring steel
According to the chemical composition, spring steel can be divided into two types: carbon spring steel and alloy spring steel. The steel number representation method is that the former is basically the same as high-quality carbon structural steel, and the latter is basically the same as alloy structural steel.
8 rolling bearing steel
display method:High carbon chromium bearing steel: letter G+Cr element symbol and number
Carburized bearing steel: letter G + number + main alloy element symbol and number + trace alloy element symbol + (quality grade symbol)
①The steel number is prefixed with the letter “G”, which means rolling bearing steel.
②The carbon content of high-carbon chromium bearing steel steel grades is not marked, and the chromium content is expressed in thousandths, such as GCr15. The steel number representation method of carburized bearing steel is basically the same as that of alloy structural steel. SGS / TUV factory cnc machining parts CNC metal cutting service
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 thousandths. For example Cr12, CrWMn, 9SiCr, 3Cr2W8V.
②The 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 thousandths, and “0” is added before the number indicating the content, so that it can be expressed in a few percent with the general element content. Distinguished, such as Cr06.
③The steel grade of high-speed tool steel generally does not indicate the carbon content, but only indicates a few percent of the average content of various alloying elements. For example, the steel grade of tungsten-based high-speed steel is expressed as “W18Cr4V”. The steel number with the letter “C” means that its carbon content is higher than that of the general steel number without “C”.
10 stainless steel and heat-resistant steel
① The carbon content in the steel grade is expressed in thousandths. For example, the average carbon content of "2Cr13" steel is 0.2%. If the carbon content in the steel is ≤0.03% or ≤0.08%, the steel number is preceded by "00" and "0" respectively, such as 00Cr17Ni14Mo2, 0Cr18Ni9, etc. SGS / TUV factory cnc machining parts CNC metal cutting service②The main alloying elements in the steel are expressed in percent, while titanium, niobium, zirconium, nitrogen…etc.
11 welding rod steel
Its steel number is preceded by the letter “H” to distinguish it from other steels. For example, stainless steel welding wire is “H2Cr13”, which can be distinguished from stainless steel “2Cr13”.
12 Electrical silicon steel
①The steel number is composed of letters and numbers. The first letter of the steel number DR means hot-rolled silicon steel for electrical use, DW means cold-rolled non-oriented silicon steel for electrical use, and DQ means cold-rolled oriented silicon steel for electrical use.
②The number after the letter indicates 100 times the iron loss value (W/kg).
③The letter “G” at the end of the steel number indicates that it is tested at a high frequency; the one without “G” indicates that it is tested at a frequency of 50 cycles. SGS / TUV factory cnc machining parts CNC metal cutting service
For example, the steel grade DW470 indicates that the maximum iron loss per unit weight of cold-rolled non-oriented silicon steel products for electrical purposes at a frequency of 50 Hz is 4.7W/kg.
13 pure iron for electricians
① Its grade is composed of the letter “DT” and numbers. “DT” means pure iron for electricians, and the number means the sequence number of different grades, such as DT3.
②The letters added after the number indicate the electromagnetic performance: A—advanced, E—extra, C—super, such as DT8A. SGS / TUV factory cnc machining parts CNC metal cutting service