Steel grade knowledge

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Steel number expression method 1. Overview of my country's steel grade expression method. The steel grade is referred to as the steel number. It is the name given to each specific steel product and is a common language for people to understand steel. my country’s steel grade expression method is based on * * It is stipulated in the standard "Steel Product Grade Representation Method" (GB/T221-2000) and came into effect on November 1, 2000. Product brands are generally represented by a combination of Chinese pinyin letters, chemical element symbols and Arabic numerals. Right now: ①The chemical elements in the steel grade are represented by international chemical symbols, such as Si, Mn, Cr... etc. Mixed rare earth elements are represented by "RE" (or "Xt"). ②The product name, usage, smelting and pouring methods, etc. are generally represented by abbreviated Chinese pinyin letters. ③The content (%) of the main chemical elements in steel is represented by Arabic numerals. When Chinese pinyin letters are used to represent product names, uses, characteristics and process methods, the first letter is generally selected from the Chinese pinyin representing the product name. When the letters selected by another product are repeated, you can use the second letter or the third letter instead, or select the first pinyin letter of two Chinese characters at the same time. If there are currently no Chinese characters or Chinese pinyin available, the symbols will be English letters. 2. Classification description of the steel grade expression method in my country 1. Carbon structural steel and low alloy high-strength structural grade expression methods The steel used above is usually divided into two categories: general-purpose steel and special-purpose steel. The grade representation method consists of the Chinese pinyin letters of the steel's yield point or yield strength, the yield point or yield strength value, the quality grade of the steel, and the degree of deoxidation of the steel, which is actually composed of 4 parts. ①General structural steel uses the pinyin letter "Q" which represents the yield point. The yield point value (unit: MPa) and the symbols such as quality grade (A, B, C, D, E) and deoxidation method (F, b, Z, TZ) specified in Table 1 are used to form a grade in order. For example: The grade of carbon structural steel is expressed as: Q235AF，Q235BZ ； The grade of low alloy high strength structural steel is expressed as: Q345C，Q345D。 Q235BZ represents killed carbon structural steel with yield point value ≥235MPa and quality grade B. The two grades of Q235 and Q345 are the most typical grades of engineering steel, with the largest production and usage, and the most widely used grades. These two brands are available in almost all countries in the world. In the grade composition of carbon structural steel, the symbol "Z" for killed steel and the symbol "TZ" for special killed steel can be omitted, for example: The grades of Q235 steel with quality grades C and D respectively should be Q235CZ and Q235DTZ, but can be omitted as Q235C and Q235D. Low-alloy high-strength structural steel includes killed steel and special killed steel, but the symbol indicating the deoxidation method is not added at the end of the grade. ②Special structural steel is generally represented by the symbol "Q" representing the yield point of the steel, the yield point value and the symbol representing the product usage specified in Table 1, such as: The steel grade for pressure vessels is expressed as "Q345R” ； The grade of weathering steel is Q340NH ； Q295HP steel grade for welding gas cylinders ； Q390g boiler steel grade ； Q420q bridge steel grade. ③According to needs, the grade of general low-alloy high-strength structural steel can also be expressed in order using two Arabic numerals (indicating the average carbon content, in ten thousandths) and chemical element symbols. ； The grade of special low-alloy high-strength structural steel can also be expressed in sequence using two Arabic numerals (indicating the average carbon content in parts per ten thousand) and chemical element symbols, as well as the symbols specified in Table 1 to represent product uses. 2. High-quality carbon structural steel and high-quality carbon spring steel grade designation method: High-quality carbon structural steel uses two Arabic numerals (in ten thousandths to represent the average carbon content) or Arabic numerals and element symbols, and the symbols specified in Table 1 are combined to form a grade. ①For boiling steel and semi-killed steel, add the symbols "F" and "b" respectively at the end of the grade. For example: Boiling steel with an average carbon content of 0.08%, its grade is expressed as "08F” ； The grade of semi-killed steel with an average carbon content of 0.10% is expressed as "10b". ②Killed steel (S and P ≤ 0.035% respectively) is generally not marked with a symbol. For example: The grade of killed steel with an average carbon content of 0.45% is expressed as "45". ③For high-quality carbon structural steel with a higher manganese content, the manganese element symbol is added after the Arabic numeral indicating the average carbon content. For example: The grade of steel with an average carbon content of 0.50% and a manganese content of 0.70% to 1.00% is expressed as "50Mn". ④For high-grade high-quality carbon structural steel (S and P ≤ 0.030% respectively), add the symbol "A" after the grade. For example: The grade of high-quality carbon structural steel with an average carbon content of 0.45% is expressed as "45A". ⑤Special grade high-quality carbon structural steel (S≤0.020%, P≤0.025%), add the symbol "E" after the grade. For example: The grade of special-grade high-quality carbon structural steel with an average carbon content of 0.45% is expressed as "45E". The expression method of high-quality carbon spring steel grades is the same as the expression method of high-quality carbon structural steel grades (65, 70, 85, and 65Mn steel exist simultaneously in the two standards of GB/T1222 and GB/T 699). 3. Representation method of alloy structural steel and alloy spring steel grades ① Alloy structural steel grades are represented by Arabic numerals and standard chemical element symbols. Use two Arabic numerals to indicate the average carbon content (in parts per 10,000) and place it at the head of the grade. The expression method of alloy element content is:: When the average content is less than 1.50%, only the elements are indicated in the brand name, and the content is generally not indicated. ； When the average alloy content is 1.50% to 2.49%, 2.50% to 3.49%, 3.50% to 4.49%, 4.50% to 5.49%, etc., it is written as 2, 3, 4, 5... after the alloy elements. For example: For alloy structural steel with an average content of carbon, chromium, manganese and silicon of 0.30%, 0.95%, 0.85% and 1.05% respectively, when the S and P content are ≤0.035% respectively, the grade is expressed as "30CrMnSi". Advanced high-quality alloy structural steel (S and P content ≤0.025% respectively) is represented by adding the symbol "A" at the end of the grade. For example: “30CrMnSiA”。 For special grade high-quality alloy structural steel (S≤0.015%, P≤0.025%), add the symbol "E" at the end of the grade, for example: “30CrM nSiE”. For special alloy structural steel grades, the symbol representing the product use specified in Table 1 should be added to the head (or tail) of the grade. For example, the steel number of 30CrMnSi steel specially used for rivet screws is ML30CrMnSi. ②The expression method of alloy spring steel grades is the same as that of alloy structural steel. For example: Spring steel with an average content of carbon, silicon, and manganese is 0.60%, 1.75%, and 0.75% respectively, and its grade is expressed as "60Si2Mn". For high-grade high-quality spring steel, add the symbol "A" at the end of the grade, and its grade is expressed as "60Si2MnA". 4. Free-cutting steel grade representation method: Free-cutting steel is represented by standard chemical element symbols, symbols specified in Table 1 and Arabic numerals. Arabic numerals indicate average carbon content (in parts per 10,000). ①For sulfur-added free-cutting steel and sulfur- and phosphorus-added free-cutting steel, the free-cutting element symbol is not added after the symbol "Y" and the Arabic numeral. For example: The grade of free-cutting steel with an average carbon content of 0.15% is expressed as "Y15". ②For sulfur-added or sulfur- and phosphorus-added free-cutting steels with higher manganese content, the manganese element symbol is added after the symbol "Y" and the Arabic numeral. For example : Free-cutting steel with an average carbon content of 0.40% and a manganese content of 1.20% to 1.55% is designated as "Y40Mn". ③For free-cutting steel containing free-cutting elements such as calcium and lead, the free-cutting element symbol is added after the symbol "Y" and the Arabic numeral. For example: “Y15Pb”, “Y45Ca”. 5. The grade representation method of non-quenched and tempered mechanical structural steel. For non-quenched and tempered mechanical structural steel, the symbols "YF" and "F" are added to the head of the grade respectively to indicate easy-cutting non-quenched and tempered mechanical structural steel and non-quenched and tempered mechanical structural steel for hot forging. Other contents of the grade representation method are the same as those of alloy structural steel. For example: “YF35V", "F45V". 6. Tool steel grade representation method Tool steel is divided into three categories: carbon tool steel, alloy tool steel and high-speed tool steel. ①Carbon tool steel is represented by standard chemical element symbols, symbols specified in Table 1 and Arabic numerals. Arabic numerals indicate average carbon content (in parts per thousand). a. For ordinary manganese-containing carbon tool steel, the tool steel symbol "T" is followed by an Arabic numeral. For example: The grade of carbon tool steel with an average carbon content of 0.80% is expressed as "T8". b. For carbon tool steel with higher manganese content, add the manganese element symbol after the tool steel symbol "T" and the Arabic numeral. For example: “ T8Mn”。 c. For high-grade high-quality carbon tool steel, add “A” at the end of the grade. For example: “T8MnA”。 ②Alloy tool steel and high-speed tool steel The grades of alloy tool steel and high-speed tool steel are expressed in the same way as the grades of alloy structural steel. It is represented by alloy element symbols and Arabic numerals specified by the standard, but the average carbon content number is generally not marked, such as: The alloy tool steel has an average carbon content of 1.60%, chromium, molybdenum, and vanadium content of 11.75%, 0.50%, and 0.22% respectively. Its grade is expressed as "Cr12MoV” ； The high-speed tool steel with an average carbon content of 0.85% and a tungsten, molybdenum, chromium, and vanadium content of 6.00%, 5.00%, 4.00%, and 2.00% respectively has a brand name of "W6Mo5Cr4V2". If the average carbon content is less than 1.00%, one Arabic numeral can be used to express the carbon content (in thousandths). For example: The alloy tool steel with an average carbon content of 0.80%, a manganese content of 0.95%, and a silicon content of 0.45% is designated as "8MnSi". For low chromium (average chromium content <1.00%) alloy tool steel, add the number "0" before the chromium content (in parts per thousand). For example: The grade of alloy tool steel with an average chromium content of 0.60% is expressed as "Cr06". 7. The plastic mold steel grade indication method. Except for adding the symbol "SM" on the head, the plastic mold steel grade indication method is the same as the high-quality carbon structural steel and alloy tool steel grade indication method. For example: Carbon plastic mold steel with an average carbon content of 0.45%, its grade is expressed as "SM45” ； The alloy plastic mold steel with an average carbon content of 0.34%, a chromium content of 1.70%, and a molybdenum content of 0.42% is designated as "SM3Cr2Mo". 8. Bearing steel grade representation method Bearing steel is divided into four categories: high carbon chromium bearing steel, carburized bearing steel, high carbon chromium stainless bearing steel and high temperature bearing steel. ①For high carbon chromium bearing steel, the symbol "G" is added to the head of the grade, but the carbon content is not indicated. The chromium content is expressed in parts per thousand, and other alloying elements are expressed in terms of the alloy content of the alloy structural steel. For example: The grade of bearing steel with an average chromium content of 1.50% is expressed as "GCr15". ②Carburized bearing steel is represented by the grade of alloy structural steel, and the symbol "G" is added to the head of the grade. For example: “G20 CrNiMo”. High-grade high-quality carburized bearing steel, add "A" at the end of the grade. For example: “G20CrNiMoA”。 ③High-carbon chromium stainless bearing steel and high-temperature bearing steel are represented by grades of stainless steel and heat-resistant steel, without the symbol "G" at the head of the grade. For example: High carbon chromium stainless bearing steel "9Cr18" and high temperature bearing steel "10Cr14Mo". 9. How to express the grades of stainless steel and heat-resistant steel. The grades of stainless steel and heat-resistant steel are represented by the alloy element symbols and Arabic numerals specified by the standard. For cutting stainless steel and easy-cutting heat-resistant steel, add "Y" at the head of the grade. Generally, an Arabic numeral is used to express the average carbon content (in thousandths) ； When the average carbon content is ≥1.00%, use two Arabic numerals to express it. ； When the upper limit of carbon content is less than 0.10%, “0” is used to represent the carbon content. ； When the upper limit of carbon content is ≤0.03% and >0.01% (ultra-low carbon), the carbon content is expressed as “03” ； When the carbon content is upper limit (very low carbon when ≤0.01%), “01” represents the carbon content. When there is no lower limit for carbon content, Arabic numerals are used to indicate the upper limit of carbon content. The expression method of alloy element content is the same as that of alloy structural steel. For example: The grade of stainless steel with an average carbon content of 0.20% and a chromium content of 13% is expressed as "2Cr13” ； The upper limit of carbon content is 0.08%, the average chromium content is 18%, and the nickel content is 9% chromium-nickel stainless steel. Its grade is expressed as "0Cr18Ni9” ； The upper limit of carbon content is 0.12% and the average chromium content is 17%. The grade of sulfur-added free-cutting chromium stainless steel is expressed as "Y1Cr17"” ； High-carbon chromium stainless steel with an average carbon content of 1.10% and a chromium content of 17% is designated as "11Cr7"” ； The upper limit of carbon content is 0.03%, the average chromium content is 19%, and the nickel content is 10% ultra-low carbon stainless steel. Its grade is expressed as "03Cr19Ni10” ； The upper limit of carbon content is 0.01%, the average chromium content is 19%, and the nickel content is 11%. The grade of extremely low carbon stainless steel is expressed as "01Cr19Ni11". The current domestic standards for stainless and heat-resistant steel are revised with reference to JIS standards, but the method of expressing grades of stainless and heat-resistant steel is different from standards in Japan and other countries. We express it by alloy elements and average C content, while Japan expresses it by letters and Arabic numerals indicating the purpose. For example, stainless steel grades SUS202, SUS316, SUS430, S-steel (steel), U-use (purpose), S-stainless (stainless steel). For example, heat-resistant steel grades, SUH309, SUH330, SUH660, H-Heatresistins. Different numbers in the grade indicate various types of stainless and heat-resistant steel. Japan represents various types of stainless and heat-resistant steel products by adding corresponding letters after the brand name, such as stainless steel rod SUS-B, hot-rolled stainless steel plate SUS-HP; heat-resistant steel rod SUHB, heat-resistant steel plate SUHP. Britain, the United States and other Western countries * * The method of expressing stainless steel heat-resistant steel grades is basically the same as that in Japan. It is mainly expressed by Arabic numerals, and the numbers expressed are the same, that is, the grades are the same. Because Japan’s stainless and heat-resistant steel is sourced from the United States. 10. Welding steel grade indication method Welding steel includes welding carbon steel, welding alloy steel and welding stainless steel, etc. The way to indicate the grade is to add the symbol "H" to the head of each type of welding steel grade. For example: “H08", "H08Mn2Si", "H1Cr18Ni9". For high-grade high-quality welding steel, add the symbol "A" at the end of the grade. For example: “H08A", "08Mn2SiA". 11. The number of silicon steel for electrical purposes consists of numbers, letters and numbers. The letter symbols of non-oriented and oriented silicon steel are "W" and "Q" respectively. The thickness is placed in the front, the letter symbol is placed in the middle, and the iron loss value is placed in the back, such as 30Q113. In grain-oriented silicon steel, the letter symbols "G" and "Q" for high magnetic induction are placed together, for example, 30QG113. The number after the letter represents 100 times the iron loss value (W/kg). The letter "G" indicates that it is tested at high frequency. ； If "G" is not added, it means that it was tested at a frequency of 50 cycles. 30Q113 indicates that the maximum unit weight iron loss value of cold-rolled oriented silicon steel products for electrical applications at a frequency of 50 Hz is 1.13W/kg. The expression method of cold-rolled silicon steel is consistent with the Japanese standard (JISC2552-86), but the letter symbols are different. For example, the grade of oriented silicon steel is 27Q140, the corresponding JIS grade is 27G140, and the corresponding JIS grade of 30QG110 is 30P110 (G: Represents ordinary materials, P: indicates high orientation). The non-oriented silicon steel grade is 35W250, and the corresponding JIS grade is 35A250. 1． Austenitic steel (1) 1Cr17Mn6Ni15N ； (2)1Cr18Mn8Ni5N ； (3)1Cr18Ni9 ； (4)1Cr18Ni9Si3 ； (5)0Cr18Ni9 ； (6)00Cr19Ni10 ； (7)0Cr19Ni9N ； (8)0Cr19Ni10NbN ； (9)00Cr18Ni10N ； (10)1Cr18Ni12 ； (11) 0Cr23Ni13 ； (12)0Cr25Ni20 ； (13) 0Cr17Ni12Mo2 ； (14) 00Cr17Ni14Mo2 ； (15) 0Cr17Ni12Mo2N ； (16) 00Cr17Ni13Mo2N ； (17) 1Cr18Ni12Mo2Ti ； (18) 0Cr18Ni12Mo2Ti ； (19) 1Cr18Ni12Mo3Ti ； (20) 0Cr18Ni12Mo3Ti ； (21) 0Cr18Ni12Mo2Cu2 ； (22) 00Cr18Ni14Mo2Cu2 ； (23) 0Cr19Ni13Mo3 ； (24) 00Cr19Ni13Mo3 ； (25) 0Cr18Ni16Mo5 ； (26) 1Cr18Ni9Ti ； (27) 0Cr18Ni10Ti ； (28) 0Cr18Ni11Nb ； (29) 0Cr18Ni13Si4 2． Austenitic-ferritic steel (30) 0Cr26Ni5Mo2 ； (31)00Cr18Ni5Mo3Si2 ； 3. Ferritic steel (32) 0Cr13Al ； (33) 00Cr12 ； (34)1Cr15 ； (35)1Cr17 ； (36)1Cr17Mo ； (37)00Cr17Mo ； (38)00Cr18Mo2 ； (39)00Cr30Mo2 ； (40)00Cr27Mo 4． Martensitic steel (41) 1Cr12 ； (42)0Cr13 ； (43) ； 1Cr13 ； (44)2Cr13 ； (45)3Cr13 ； (46)4Cr13 ； (47)3Cr16 ； (48)7Cr17 5． Precipitation hardened steel (49) 0Cr17Ni7Al 4. Approximate comparison of commonly used stainless steel grades in my country and Japan 1. comparison table: Japan (JIS) China (GB) SUS304 0Cr18Ni9(0Cr19Ni9) SUS 304L 00Cr19Ni10(00Cr18Ni10) SUS 309S 0Cr23Ni13 SUS 310S 0Cr25Ni20(1Cr25Ni20Si2) SUS 316 0Cr17Ni12Mo2(0Cr18Ni12Mo2Ti) SUS 316L 00Cr17Ni14Mo2 SUS 321 1Cr18Ni9Ti(0Cr18Ni9Ti) SUS 430 1Cr17 SUS 403 1Cr12 SUS 410 1Cr13 SUS 420J1 2Cr13 SUS 420J2 3Cr13 SUS 431 1Cr17Ni2 2. The brand name is followed by NO. 1 means heat treatment, pickling or similar treatment after hot rolling ； NO. 2 means heat treatment, pickling or corresponding treatment after cold rolling ； NO. 2B means heat treatment, pickling or similar treatment after cold rolling, and finally cold rolling to obtain appropriate smoothness. Such as 304NO. 1 Stainless steel plate means hot-rolled stainless steel plate with grade 304. Another example is 321-2B, which represents the cold-rolled stainless steel plate with grade 321. The surface requires heat treatment, pickling or similar treatment after cold rolling, and finally cold rolling to obtain an appropriate smoothness. Comparison table between stainless steel grades and the United States, Japan and Europe Category China, United States, Japan and Europe Martensitic stainless steel Cr13 type 410SUS410SAF2301 1Cr17Ni2431SUS431SAF2321 9Cr18440CSUS440c 0Cr17Ni4Cu4Nb17-4PHSUH630 1Cr12Ni3MoWVXM32 DIN1.4313 2Cr12MoVNbN SUH600 2Cr12NiMoWV SUH616 Dual phase steel 00Cr18Ni5Mo3Si2S315003RE60 00Cr22Ni5Mo3NS31803329J3L1SAF2205 00Cr25Ni6Mo2N 329J1L1R-4 00Cr25Ni7Mo3NS31260329J4LSAF2507 00Cr25Ni6Mo3CuN S32550 Ferrite 0Cr13410SSUS410S 00Cr17Ti 00Cr18Mo2Ti Austenitic stainless steel 0Cr18Ni9Ti321SUS321SAF2337 00Cr19Ni10304LSUS304L 0Cr17Ni12Mo2316SUS316SAF2343 0Cr17Ni14Mo2316LSUS312L 00Cr19Ni13Mo3317LSUS317L ZG00Cr19Ni10CF3SCS19A ZG00Cr17Ni14Mo2CF3MSCS16A 0Cr25Ni20310SSUS310S 00Cr20Ni18Mo6CuNS31254 254SMO 00Cr20Ni25Mo4.5Cu904L 2RK65 00Cr25Ni22MoNS31050 2RE6 This post was last edited by devilztj on 2009-3-5 19:34 ]