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    Common metal grade representation method for Hengshui steel structure

    author:Bohai Steel Structure Co., Ltd.

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    time:2019-08-23 09:51:20

    mechanical parts used in a variety of metal materials, in order to produce, easy to manage, orderly, different standards for a predetermined metal material representation thereof grade To show unity and ease of adoption and use. Now I will introduce some common methods of metal material grades to the reader.

       I. Steel product grade representation method (refer to GB/T221—2000)

      1. standard

      GB/T221—2000 The standard is revised on April 1, 2000 after the revision of the foreign steel product grade representation method and the domestic steel product grade representation method ( such as Q345 instead of 16Mn). And opened on November 1, 2000 Implementation.

      2. main technical content changes

       (1) due to some grades of steel products have their specific standard Therefore, the original standard iron alloy, casting alloy, high temperature alloy, precision alloy, corrosion resistant alloy and cast iron, cast steel, powder materials and other brand representation methods were eliminated.



       (2) new steel The emergence of products has improved the original standards. The new standard has added de-carbonized low-phosphorus iron, vanadium-containing pig iron JP2, cast wear-resistant pig iron, guaranteed hardenability steel, non-tempered mechanical structural steel, plastic mold steel, oriented silicon steel (for telecommunications) and other brand representation.



       (3) are not suited Technology Development and production of steel grades that are inconsistent with production have been completely changed or modified. For example, carbon structural steel A 3 is changed to Q235, and low alloy high strength structural steel 16Mn is changed to Q345. The method of indicating the number of stainless steel, heat-resistant steel and cold-rolled silicon steel has also been modified.

       (4) the original standard "grades of steel products for example representation" in Table 3, due to the new standard does not apply to be deleted .

      3. steel product grade representation basic principle of the method

       (1) Where the steel products of national standards and industry standards should be written according to the standard number representation method specified in GB/T221-2000. Steel product grades that are not in compliance with the regulations shall be changed when the standards are revised. For some new steel products, the grades shall also be graded accordingly.

      (2) representation of product grades, generally using Chinese pinyin letters, chemical element symbols and Arabic numerals method together to represent.

      (3) When using Chinese pinyin letters to indicate product name, purpose, characteristics and process, generally from the representative Select the first letter of the Chinese phonetic language product name. When repeating the letter selected for another product, you can use the second letter or the third letter, or select the first of the two Chinese characters.

       (4) Temporarily no Chinese characters and Chinese pinyin, the symbols are English letters.

      4. steel product name, purpose, characteristics and process methods that symbol (excerpt) 58 748xbr style="margin: 0px; padding: 0px; list-style: none; font-family: Microsoft elegant black, blackbody, Arial, Helvetica, sans-serif; font-size: 14.6667px; white-space: normal; "/>
       steel product name, purpose, characteristics and process methods that symbol table 1.

      5. grades of steel products representation examples and explanations

       (1) cast iron grade indicates that the cast iron grade is represented by the symbols and Arabic numerals specified in Table 1.

      1 Arabic numerals indicate the average silicon content (in thousands of parts). For example, the iron for casting with a silicon content of 2.75% to 3.25% is represented by "Z30"; the pig iron for steelmaking with a silicon content of 0.85% to 1.25% is represented by "L10".

      2 vanadium-containing pig iron and decarburized low-phosphorus iron, the Arabic numerals indicate the average content of vanadium and carbon, respectively. Few dollars). Example : vanadium-containing pig iron with vanadium content not less than 0.40%, the grade is expressed as "F40"; the carbon content is 1.20% ~ 1.60% of decarburized low-phosphorus iron for steelmaking, the grade is expressed as "TL14" ".

      (2) Carbon structural steel and low alloy high strength structural grade designation The above steel is usually divided into general steel and Steel two categories.

      1 general structural steel with the pinyin letter "Q" representing the yield point. The value of the yield point (in MPa) and the symbol of the mass of specified in Table 1, the deoxidation method, etc., are grouped in order. For example: carbon structural steel grades are expressed as: Q235AF, Q235BZ; low alloy high strength structural steel grades are expressed as: Q345C, Q345D.

       grade composition of carbon structural steel, killed steel symbol " The Z" and special killed steel symbol "TZ" can be omitted. For example, Q235 steel with grade grades of grade C and grade D, respectively, should be Q235CZ and Q235DTZ, but can be omitted as Q235C and Q235D.

       low alloy high strength structural steel with killed steel and special killed steel, but the tail of the grade is not written to indicate deoxidation symbol.

      2 special structural steel generally uses the symbol "Q" representing the yield point of steel, the value of the yield point and the values specified in Table 1. The symbol representing the product use , etc., for example, the pressure vessel is indicated by the steel grade as "Q345R"; the weathering steel is indicated by the grade: Q340NH.

      3, as required, the grade of general low alloy high strength structural steel can also use two Arabic numerals (in flat parts per meter average carbon content) and standard elemental symbols; special high-strength low-alloy structural steel grades, in addition to the general composition, there should be write specified in Table 1 symbol represents the product use.

       (3) high-quality carbon steel and carbon spring steel grades representation

    47401 The x  premium carbon structural steel is a combination of two Arabic numerals (average carbon content in parts per million) or Arabic numerals and elements , symbols specified in Table 1.

      1 boiling steel and semi-killed steel, with the symbols "F" and "b" at the end of the grade. For example: boiling Tenggang with an average carbon content of 0.08%, whose grade is indicated as "08F"; semi-killed steel with an average carbon content of 0.10%, whose grade is expressed as "10b".

      2 killed steel (S, P ≤ 0.035% respectively) is generally not marked. For example, a calming steel with an average carbon content of 0.45% is indicated by a grade of "45".

      3 high-quality carbon-structured steel with high manganese content, plus manganese after the Arabic numerals representing the average carbon content Symbol. For example: average carbon content is 0.50%, manganese content is 0.70% ~ 1.00% steel, the grade is expressed as "50Mn".

      ④ High quality carbon structural steel (S, P is ≤ 0.030%), and the symbol "A" is added after the grade. For example, an advanced high-quality carbon structural steel with an average carbon content of 0.45% is indicated by the grade "45A".

      5 premium quality carbon structural steel (S≤0.020%, P≤0.025%), with the symbol "E" after the grade. For example, a premium quality carbon structural steel with an average carbon content of 0.45% is indicated by the grade "45E".

       high quality carbon spring steel grades are expressed in the same way as high quality carbon structural steel grades (65, 70, 85, 65Mn steel exists in both GB/T1222 and GB/T 699 standards).

       (4) alloy structural steel and alloy spring steel grade representation method 58848x/span>

      1 alloy structural steel grades are represented by Arabic numerals and standard chemical element symbols.

       uses two Arabic numerals to indicate the average carbon content (in parts per million), placed at the head of the grade.

       alloy element content is expressed as: when the average content is less than 1.50%, only the elements are indicated in the grade, Not indicated; average alloy content is 1.50% ~ 2.49%, 2.50% ~ 3.49%, 3.50% ~ 4.49%, 4.50% ~ 5.49%, ..., after the alloying elements correspondingly written 2, 3, 4, 5 ....

       For example: carbon, chromium, manganese, silicon, the average content is 0 □ 30%, 0.95%, 0.85%, 1.05% Alloy steel, when S, P content were ≤0.035%, the grade is expressed as "30CrMnSi".

       high-quality alloy structural steel (S, P content ≤ 0.025%, respectively), with the symbol "A" at the end of the brandFor example: "30 CrMnSiA".

       premium quality alloy steel (S≤0.015%, P≤0.025%), the rear plus sign in Grade "E", for example: "30CrM nSiE" .

       special alloy structural steel grade should be specified in the head (or tail) of the grade plus the symbol for the use of the product .

      2 alloy spring steel grades are expressed in the same way as alloy structural steel. For example, the average content of carbon, silicon, and manganese is 0.60%, 1.75%, and 0.75%, respectively, and the grade is expressed as "60Si2Mn". High-quality spring steel, with the symbol "A" at the end of the grade, the grade is indicated as "60Si2MnA".

      (5) Free-cutting steel grade representation Free-cutting steel using standard chemical element symbols, symbols specified in Table 1 and Arab Digital representation. Arabic numerals indicate the average carbon content (in parts per million).

      1 vulcanized free-cutting steel and vulcanized, phosphorus free-cutting steel, not easy to cut after the symbol "Y" and Arabic numerals Element symbols.

       example : Free-cutting steel with an average carbon content of 0.15%, the grade is expressed as "Y15".

      2 higher manganese content vulcanized or vulcanized, phosphorus free-cutting steel with the symbol "Y" and Arabic numerals followed by manganese Symbol. For example, : free-cutting steel with an average carbon content of 0.40% and a manganese content of 1.20% to 1.55%, and its grade is expressed as "Y40Mn".

      3 Free cutting steel with free cutting elements such as calcium and lead, with easy cutting after the symbol "Y" and Arabic numerals Prime symbol. Example is as follows: "Y15Pb", "Y45Ca".

      (6) Non-tempered mechanical structural steel grade representation Non-tempered mechanical structural steel, respectively added in the head of the grade "YF" and "F" represents a non-heat cutting structural steel and non-heat hot forging steel, and the grades that other content of the alloy steel in the same manner. For example: "YF35V", "F45V".

      (7) Tool steel grade representation Tool steel is divided into carbon tool steel, alloy tool steel and high speed tool steel.

      1 carbon tool steel is indicated by the standard chemical element symbol, the symbols specified in Table 1, and the Arabic numerals. The Arabic numerals indicate the average carbon content of the (in thousands of parts).

      a. ordinary manganese-containing carbon tool steel, which is Arabic numerals after the tool steel symbol "T". For example, a carbon tool steel with an average carbon content of 0.80% is indicated by the grade "T8".

      b. higher manganese content carbon tool steel, with manganese in the tool steel symbol "T" and Arabic numerals symbol. For example: " T8Mn".

      c. high quality carbon tool steel, add "A" at the end of the grade. For example: "T8MnA".

      ② alloy tool steel and high speed tool steel

       alloy tool steel, high speed tool steel grades that the same method and alloy steel grades representation. It is expressed by the standard gold symbol and Arabic numerals, but generally does not indicate the average carbon content. For example, the average carbon content is 1.60?305x, and the content of chromium, molybdenum and vanadium is 11.75% and 0.50%, respectively. 0.22% alloy tool steel, the grade is expressed as "Cr12MoV"; the average carbon content is 0.85%, and the high-speed tool steel containing tungsten, molybdenum, chromium and vanadium contents are 6.00%, 5.00%, 4.00%, 2.00%, respectively. Its grade is expressed as "W6Mo5Cr4V2".

       If the average carbon content is less than 1.00%, an Arabic numeral can be used to indicate the carbon content (in thousands of parts) meter). For example, Ping has an alloy steel with a carbon content of 0.80%, a manganese content of 0.95%, and a silicon content of 0.45%, and its grade is expressed as "8MnSi".

       low chromium (average chromium content <1.00%) alloy tool steel, before the chromium content (in thousands of parts) plus the number " 0". For example, an alloy tool steel with an average chromium content of 0.60% is indicated by the brand "Cr06".

      (8) Plastic mold steel grade designation Plastic mold steel grade except the head with the symbol "SM", the other representations and high quality carbon structural steel It is the same as the alloy tool steel plate . For example: carbon plastic mold steel with an average carbon content of 0.45%, the grade is expressed as "SM45"; the average carbon content is 0.34%, the chromium content is 1.70%, and the alloy plastic mold steel containing 0.42% molybdenum is 0.42%. Its brand number is expressed as "SM3Cr2Mo".

      (9) bearing steel grade representation bearing steel is divided into high carbon chromium bearing steel, carburized bearing steel, high carbon chromium stainless bearing steel and high-temperature bearing steel four categories.

      1 high carbon chromium bearing steel, with the symbol "G" in the head of the grade, but does not indicate the carbon content. The chromium content is in parts per thousand, and the other alloying elements are expressed as the alloy content of the alloy structural steel. For example, a bearing steel with an average chromium content of 1 □ 50% indicates that the is “GCr15”.

      2 carburized bearing steel, using the alloy structural steel grade indication method, plus the symbol "G" in the head of the gradeFor example: "G20 CrNiMo".

       high quality carburized bearing steel, add "A" at the end of the grade. For example: "G20CrNiMoA".
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