Metal materials used in mechanical parts are various. In order to make production and management convenient and orderly, the relevant standards stipulate the method of representing their grades for different metal materials to show uniformity and ease of adoption and use. We will now give some brief introductions to the readers of the commonly used metal materials.
First, the steel product brand representation method (refer to GB/T221-2000)
1. Basic profile of the standard
The GB/T221-2000 standard was issued on April 1, 2000 after being revised with reference to the representation of foreign steel products and the indication of changes in the domestic steel product grades (such as Q345 instead of 16Mn), and on November 1, 2000. Started.
2. Changes in major technical content
(1) Since some steel product grades have their own special standards, the grades of iron alloys, cast alloys, high-temperature alloys, precision alloys, corrosion-resistant alloys, cast irons, cast steels, powder materials, etc. have been eliminated from the original standards.
(2) The emergence of some new steel products has further improved the original standards. The new standard adds grades such as decarburized low-phosphorus iron pellets, vanadium-containing pig iron JP2, cast wear-resistant pig iron, guaranteed hardenability steel, non-quenched and tempered mechanical structural steel, plastic die steel, and oriented silicon steel (for telecommunications).
(3) Some steel grades that do not adapt to the development of science and technology and are inconsistent with production have been completely changed or modified. Such as carbon structural steel A 3 changed to Q235, low alloy high strength structural steel 16Mn to Q345 and so on. Modifications have also been made to the designation of stainless steel, heat-resistant steel, and cold-rolled silicon steel.
(4) Table 3 of the “Example of Iron and Steel Product Number Representation†in the original standard was deleted because it does not apply to the new standard.
3. Basic principles for the representation of steel product grades
(1) The grades of steel products in national standards and industry standards should be written according to the grades specified in GB/T221-2000. Steel grades that are not complied with the requirements should be changed when the standard is revised. Some new steel products should also be branded according to their grades.
(2) The indication of the product's brand number is generally expressed in a combination of Chinese Pinyin letters, chemical element symbols and Arabic numerals.
(3) When the Chinese Pinyin letters are used to indicate the product name, purpose, characteristics, and process method, the first letter is generally selected from the Han Pinyin that represents the product name. When the letters selected for another product are repeated, the second letter or the third letter may be used instead, or the first of the two Chinese characters may be selected at the same time.
(4) For the time being there is no Chinese character or Pinyin that can be used, the symbol is the English alphabet.
4. Symbols (extracts) of steel product names, uses, characteristics, and process methods
The symbol for the names, uses, characteristics, and processes of steel products are shown in Table 1.
5. Example and description of steel product brand representation
(1) Pig iron grades indicate method The cast iron grades are represented by the symbols specified in Table 1 and Arabic numerals.
1 Arabic numerals represent the average silicon content (in parts per thousand). For example, a foundry pig iron containing 2.75% to 3.25% of silicon is designated "Z30", and a steelmaking pig iron having a silicon content of 0.85% to 1.25% is designated "L10".
2 Vanadium-containing pig iron and decarburized low-phosphorus ferrite, and Arabic numerals mean the average content of vanadium and carbon, respectively, in several parts per thousand. For example, vanadium-containing pig iron with a vanadium content of not less than 0.40% is designated “F40â€, and decarburized low-phosphorus grain iron with a carbon content of 1.20%-1.60% is designated “TL14â€.
(2) Grades of carbon structural steels and low-alloy high-strength structures. The above steels are generally classified into general steels and special steels.
1 General-purpose structural steel uses a phonetic letter “Q†that represents the yield point. The value of the yield point (in MPa) and the quality grade, deoxidation method, etc. specified in Table 1 consist of the grades in order. For example: Carbon structural steel grades are: Q235AF, Q235BZ; Low alloy high strength structural steel grades are: Q345C, Q345D.
In the composition of carbon structural steel, the symbol “Z†for the killed steel and the symbol “TZ†for the special killed steel can be omitted. For example: Q235 steel with quality class C and D respectively, and its grades indicate Q235CZ and Q235DTZ, However, it can be omitted for Q235C and Q235D.
Low-alloy high-strength structural steels have killed steels and special killed steels, but the designation of the deoxidation method is not written on the tail of the grade.
2 Dedicated structural steel is generally represented by the symbol “Q†representing the yield point of the steel, the yield point value, and the symbol for the use of the product specified in Table 1. For example, the steel grade for the pressure vessel is represented by “Q345Râ€; the grade of the weathering steel is Represented as: Q340NH.
3 According to requirements, the grade of general low-alloy high-strength structural steel can also be composed of two Arabic numerals (average carbon content in parts per thousand) and standard element symbols; the grade of special low-alloy high-strength structural steel, in addition to general In addition to the composition, the symbols used in Table 1 to represent the use of the product should be added.
(3) High-quality carbon structural steel and high-quality carbon spring steel brand representation
High-quality carbon structural steels are combined into two grades using two digits of Arabic numerals (average carbon content expressed in parts per million) or Arabic numerals and element symbols, and the symbols specified in Table 1.
1 Boiling steel and semi-static steel, with the symbols "F" and "b" at the end of the brand. For example, boiling steel with an average carbon content of 0.08% is graded as “08Fâ€; semi-killed steel with an average carbon content of 0.10% is graded as “10bâ€.
2 Static steel (S, P ≤ 0.035% respectively) is generally not marked. For example, a killed steel with an average carbon content of 0.45% is indicated by the designation “45â€.
3 High-quality carbon structural steels with higher manganese content, followed by the manganese element symbol after the Arabic numerals representing the average carbon content. For example: Steel with an average carbon content of 0.50% and a manganese content of 0.70% to 1.00% has its brand name “50Mnâ€.
4 High-quality high-quality carbon structural steel (S, P ≤ 0.030%, respectively), after the brand name plus "A". For example: High-grade high-quality carbon structural steel with average carbon content of 0.45%, its grade is denoted as "45A".
5Special grade high quality carbon structural steel (S≤0.020%, P≤0.025%), with the symbol "E" after the brand. For example, a special high-quality carbon structural steel with an average carbon content of 0.45% is indicated by the designation “45Eâ€.
The representation method of high-quality carbon spring steel grades is the same as that of high-quality carbon structural steel grades (65, 70, 85, and 65 Mn steels exist at the same time in both GB/T1222 and GB/T 699).
(4) Alloy 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 represent the average carbon content (in parts-per-million) on the brand's head.
The alloying element content is expressed as follows: when the average content is less than 1.50%, only the elements are marked in the grade, and the content is generally not marked; the average alloy content is 1.50% to 2.49%, 2.50% to 3.49%, 3.50% to 4.49%, and 4.50% to At 5.49%,..., after the alloy elements, they are written as 2, 3, 4, 5,...
For example, alloy steels with an average content of carbon, chromium, manganese, and silicon of 0 □ 30%, 0.95%, 0.85%, and 1.05%, respectively, are graded as “30CrMnSi†when the S and P contents are ≤ 0.035% respectively. .
Advanced high-quality alloy structural steels (S, P content ≤ 0.025% respectively) are indicated by the symbol “A†at the end of the grade. For example: "30 CrMnSiA".
Special grade high quality alloy structural steel (S ≤ 0.015%, P ≤ 0.025%), with the symbol "E" at the end of the grade, eg "30CrM nSiE".
Special alloy structural steel grades shall be added to the head (or tail) of the brand plus the symbol that indicates the use of the product in Table 1.
2 Alloy spring steel grades are indicated in the same way as alloy structural steels. For example: spring steel with an average content of carbon, silicon, and manganese of 0.60%, 1.75%, and 0.75%, respectively, whose designation is “60Si2Mnâ€. Premium high-quality spring steel, with the symbol "A" at the end of the grade, and the grade "60Si2MnA".
(5) Marking method of free-cutting steel The free-cutting steel adopts the symbols of standard chemical elements, the symbols specified in Table 1, and the Arabic numerals. Arabic numerals represent the average carbon content (in parts per thousand).
1 Vulcanized free-cutting steels and vulcanized, phosphorus free machining steels, without the symbol of free-cutting elements after the symbol “Y†and Arabic numerals.
For example, a free cutting steel with an average carbon content of 0.15% is indicated by the designation "Y15".
2 Sulfur-enriched or sulfur-enriched, phosphorus-free cutting steels with a higher manganese content are added with the manganese element symbol after the symbol "Y" and Arabic numerals. For example: Free cutting steel with an average carbon content of 0.40% and a manganese content of 1.20% to 1.55%. Its grade is “Y40Mnâ€.
3 Free-cutting steels that contain free-cutting elements such as calcium and lead, plus the free-cutting element symbol after the symbol "Y" and Arabic numerals. For example: "Y15Pb", "Y45Ca".
(6) Non-quenched and tempered mechanical steel grades are indicated in non-quenched and tempered mechanical structural steels. Symbols "YF" and "F" in the brand name denote free-cutting non-quenched and tempered mechanical structural steels and non-finishing machinery for hot forging Structural steels, grades indicate that the method is the same as the alloy structural steel. For example: "YF35V", "F45V".
(7) Tool Steel Grades Tool Steels are classified into three categories: carbon tool steels, alloy tool steels, and high-speed tool steels.
1 Carbon tool steels are represented by standard chemical element symbols, symbols specified in Table 1, and Arabic numerals. Arabic numerals represent the average carbon content (in parts per thousand).
a. Ordinary manganese-containing carbon tool steel, after the tool steel symbol "T", is an Arabic numeral. For example, a carbon tool steel with an average carbon content of 0.80% is graded as "T8".
b. Higher carbon content of the carbon tool steel, plus the manganese element symbol after the tool steel symbol "T" and Arabic numerals. For example: "T8Mn".
c. High quality carbon tool steel, add "A" to the end of the grade. For example: "T8MnA".
2 alloy tool steel and high speed tool steel
Alloy tool steel and high-speed tool steel grades are indicated in the same way as alloy structural steel grades. The standard alloy elements and Arabic numerals are used, but the average carbon content is not generally specified. For example, the average carbon content is 1.60%, and the chromium, molybdenum, and vanadium contents are 11.75%, 0.50%, and 0.22%, respectively. The alloy tool steel is graded as “Cr12MoVâ€; the average carbon content is 0.85%, and the high-speed tool steels containing tungsten, molybdenum, chromium, and vanadium contents of 6.00%, 5.00%, 4.00%, and 2.00%, respectively, are indicated by their grades. It is "W6Mo5Cr4V2".
If the average carbon content is less than 1.00%, an Arabic numeral can be used to indicate the carbon content (in parts per thousand). For example, an 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 “8MnSiâ€.
Low-chromium (average chromium content <1.00%) alloy tool steel with a number “0†before the chromium content (in parts per thousand). For example, an alloy tool steel with an average chromium content of 0.60% is indicated by the designation “Cr06â€.
(8) Representation methods of plastic die steel grades In addition to the symbol “SM†on the head of plastic die steel grades, the remaining indication methods are the same as the high-quality carbon structural steel and alloy tool steel grades. For example: carbon plastic mold steel with an average carbon content of 0.45%, its brand name is “SM45â€; alloy plastic mold steel with average carbon content of 0.34%, chromium content of 1.70%, and molybdenum content of 0.42% Its brand name is "SM3Cr2Mo".
(9) Bearing steel number designation 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.
1 High-carbon chromium bearing steel, add “G†to the head of the brand, but do not indicate the carbon content. Chromium content is measured in parts per thousand, and other alloying elements are expressed as the alloy content of the alloy structural steel. For example, bearing steels with an average chromium content of 1â–¡50% are graded as “GCr15â€.
2 Carburizing bearing steel, the use of alloy structural steel grades, the other at the head of the symbol plus the symbol "G". For example: "G20 CrNiMo".
High quality carburized bearing steel, add "A" to the end of the grade. For example: "G20CrNiMoA".
3 High-carbon chromium stainless bearing steel and high-temperature bearing steel are indicated by the grades of stainless steel and heat-resistant steel. No "G" is added to the head of the brand. For example: high carbon chromium stainless bearing steel "9Cr18" and high temperature bearing steel "10Cr14Mo".
(10) Grades of stainless steel and heat-resisting steels The grades of stainless steel and heat-resisting steel are indicated by the standard alloy element symbols and Arabic numerals, and “Y†is added to the cut stainless steel and easily-cut heat-resistant steel.
The average carbon content (in parts per thousand) is generally represented by an Arabic numeral; when the average carbon content is ≥ 1.00%, it is represented by two Arabic numerals; when the upper limit of carbon content is < 0.10%, “Indicates the carbon content; when the upper limit of carbon content is ≤0.03% and >0.01% (ultra-low carbon), the carbon content is expressed by “03â€; when the upper limit of carbon content (upper carbon content is less than 0.01%), "01" indicates carbon content. When there is no lower limit for the carbon content, Arabic numerals are used to indicate the upper limit of carbon content.
Alloy element content is expressed in the same way as alloy structural steel. For example, stainless steel with an average carbon content of 0.20% and a chromium content of 13% is graded as “2Cr13â€; the upper limit of carbon content is 0.08%, the average chromium content is 18%, and the nickel content is 9%. Chrome-nickel stainless steel whose grade is denoted as "0Cr18Ni9"; vulcanized free-cutting chromium stainless steel with an upper limit of 0.12% and an average chromium content of 17%; its grade is denoted as "Y1Cr17"; the average carbon content is 1.10% , High-carbon chromium stainless steel with 17% chromium content, whose grade is denoted as "11Cr7"; ultra-low carbon stainless steel with an upper limit of 0.03%, average chromium content of 19%, and nickel content of 10%; The grade is denoted as "03Cr19Ni10"; the ultra-low carbon stainless steel whose upper limit of carbon content is 0.01%, the average chromium content is 19%, and the nickel content is 11% is indicated as "01Cr19Ni11".
(11) Method of indicating steel grades for welding
Welding steels include carbon steels for welding, alloy steels for welding, and stainless steels for welding. They are indicated by the designation “H†on the head of each type of welding steel. For example: "H08", "H08Mn2Si", "H1Cr18Ni9".
Premium high-quality welding steel, with the symbol "A" at the end of the grade. For example: "H08A", "08Mn2SiA".
First, the steel product brand representation method (refer to GB/T221-2000)
1. Basic profile of the standard
The GB/T221-2000 standard was issued on April 1, 2000 after being revised with reference to the representation of foreign steel products and the indication of changes in the domestic steel product grades (such as Q345 instead of 16Mn), and on November 1, 2000. Started.
2. Changes in major technical content
(1) Since some steel product grades have their own special standards, the grades of iron alloys, cast alloys, high-temperature alloys, precision alloys, corrosion-resistant alloys, cast irons, cast steels, powder materials, etc. have been eliminated from the original standards.
(2) The emergence of some new steel products has further improved the original standards. The new standard adds grades such as decarburized low-phosphorus iron pellets, vanadium-containing pig iron JP2, cast wear-resistant pig iron, guaranteed hardenability steel, non-quenched and tempered mechanical structural steel, plastic die steel, and oriented silicon steel (for telecommunications).
(3) Some steel grades that do not adapt to the development of science and technology and are inconsistent with production have been completely changed or modified. Such as carbon structural steel A 3 changed to Q235, low alloy high strength structural steel 16Mn to Q345 and so on. Modifications have also been made to the designation of stainless steel, heat-resistant steel, and cold-rolled silicon steel.
(4) Table 3 of the “Example of Iron and Steel Product Number Representation†in the original standard was deleted because it does not apply to the new standard.
3. Basic principles for the representation of steel product grades
(1) The grades of steel products in national standards and industry standards should be written according to the grades specified in GB/T221-2000. Steel grades that are not complied with the requirements should be changed when the standard is revised. Some new steel products should also be branded according to their grades.
(2) The indication of the product's brand number is generally expressed in a combination of Chinese Pinyin letters, chemical element symbols and Arabic numerals.
(3) When the Chinese Pinyin letters are used to indicate the product name, purpose, characteristics, and process method, the first letter is generally selected from the Han Pinyin that represents the product name. When the letters selected for another product are repeated, the second letter or the third letter may be used instead, or the first of the two Chinese characters may be selected at the same time.
(4) For the time being there is no Chinese character or Pinyin that can be used, the symbol is the English alphabet.
4. Symbols (extracts) of steel product names, uses, characteristics, and process methods
The symbol for the names, uses, characteristics, and processes of steel products are shown in Table 1.
5. Example and description of steel product brand representation
(1) Pig iron grades indicate method The cast iron grades are represented by the symbols specified in Table 1 and Arabic numerals.
1 Arabic numerals represent the average silicon content (in parts per thousand). For example, a foundry pig iron containing 2.75% to 3.25% of silicon is designated "Z30", and a steelmaking pig iron having a silicon content of 0.85% to 1.25% is designated "L10".
2 Vanadium-containing pig iron and decarburized low-phosphorus ferrite, and Arabic numerals mean the average content of vanadium and carbon, respectively, in several parts per thousand. For example, vanadium-containing pig iron with a vanadium content of not less than 0.40% is designated “F40â€, and decarburized low-phosphorus grain iron with a carbon content of 1.20%-1.60% is designated “TL14â€.
(2) Grades of carbon structural steels and low-alloy high-strength structures. The above steels are generally classified into general steels and special steels.
1 General-purpose structural steel uses a phonetic letter “Q†that represents the yield point. The value of the yield point (in MPa) and the quality grade, deoxidation method, etc. specified in Table 1 consist of the grades in order. For example: Carbon structural steel grades are: Q235AF, Q235BZ; Low alloy high strength structural steel grades are: Q345C, Q345D.
In the composition of carbon structural steel, the symbol “Z†for the killed steel and the symbol “TZ†for the special killed steel can be omitted. For example: Q235 steel with quality class C and D respectively, and its grades indicate Q235CZ and Q235DTZ, However, it can be omitted for Q235C and Q235D.
Low-alloy high-strength structural steels have killed steels and special killed steels, but the designation of the deoxidation method is not written on the tail of the grade.
2 Dedicated structural steel is generally represented by the symbol “Q†representing the yield point of the steel, the yield point value, and the symbol for the use of the product specified in Table 1. For example, the steel grade for the pressure vessel is represented by “Q345Râ€; the grade of the weathering steel is Represented as: Q340NH.
3 According to requirements, the grade of general low-alloy high-strength structural steel can also be composed of two Arabic numerals (average carbon content in parts per thousand) and standard element symbols; the grade of special low-alloy high-strength structural steel, in addition to general In addition to the composition, the symbols used in Table 1 to represent the use of the product should be added.
(3) High-quality carbon structural steel and high-quality carbon spring steel brand representation
High-quality carbon structural steels are combined into two grades using two digits of Arabic numerals (average carbon content expressed in parts per million) or Arabic numerals and element symbols, and the symbols specified in Table 1.
1 Boiling steel and semi-static steel, with the symbols "F" and "b" at the end of the brand. For example, boiling steel with an average carbon content of 0.08% is graded as “08Fâ€; semi-killed steel with an average carbon content of 0.10% is graded as “10bâ€.
2 Static steel (S, P ≤ 0.035% respectively) is generally not marked. For example, a killed steel with an average carbon content of 0.45% is indicated by the designation “45â€.
3 High-quality carbon structural steels with higher manganese content, followed by the manganese element symbol after the Arabic numerals representing the average carbon content. For example: Steel with an average carbon content of 0.50% and a manganese content of 0.70% to 1.00% has its brand name “50Mnâ€.
4 High-quality high-quality carbon structural steel (S, P ≤ 0.030%, respectively), after the brand name plus "A". For example: High-grade high-quality carbon structural steel with average carbon content of 0.45%, its grade is denoted as "45A".
5Special grade high quality carbon structural steel (S≤0.020%, P≤0.025%), with the symbol "E" after the brand. For example, a special high-quality carbon structural steel with an average carbon content of 0.45% is indicated by the designation “45Eâ€.
The representation method of high-quality carbon spring steel grades is the same as that of high-quality carbon structural steel grades (65, 70, 85, and 65 Mn steels exist at the same time in both GB/T1222 and GB/T 699).
(4) Alloy 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 represent the average carbon content (in parts-per-million) on the brand's head.
The alloying element content is expressed as follows: when the average content is less than 1.50%, only the elements are marked in the grade, and the content is generally not marked; the average alloy content is 1.50% to 2.49%, 2.50% to 3.49%, 3.50% to 4.49%, and 4.50% to At 5.49%,..., after the alloy elements, they are written as 2, 3, 4, 5,...
For example, alloy steels with an average content of carbon, chromium, manganese, and silicon of 0 □ 30%, 0.95%, 0.85%, and 1.05%, respectively, are graded as “30CrMnSi†when the S and P contents are ≤ 0.035% respectively. .
Advanced high-quality alloy structural steels (S, P content ≤ 0.025% respectively) are indicated by the symbol “A†at the end of the grade. For example: "30 CrMnSiA".
Special grade high quality alloy structural steel (S ≤ 0.015%, P ≤ 0.025%), with the symbol "E" at the end of the grade, eg "30CrM nSiE".
Special alloy structural steel grades shall be added to the head (or tail) of the brand plus the symbol that indicates the use of the product in Table 1.
2 Alloy spring steel grades are indicated in the same way as alloy structural steels. For example: spring steel with an average content of carbon, silicon, and manganese of 0.60%, 1.75%, and 0.75%, respectively, whose designation is “60Si2Mnâ€. Premium high-quality spring steel, with the symbol "A" at the end of the grade, and the grade "60Si2MnA".
(5) Marking method of free-cutting steel The free-cutting steel adopts the symbols of standard chemical elements, the symbols specified in Table 1, and the Arabic numerals. Arabic numerals represent the average carbon content (in parts per thousand).
1 Vulcanized free-cutting steels and vulcanized, phosphorus free machining steels, without the symbol of free-cutting elements after the symbol “Y†and Arabic numerals.
For example, a free cutting steel with an average carbon content of 0.15% is indicated by the designation "Y15".
2 Sulfur-enriched or sulfur-enriched, phosphorus-free cutting steels with a higher manganese content are added with the manganese element symbol after the symbol "Y" and Arabic numerals. For example: Free cutting steel with an average carbon content of 0.40% and a manganese content of 1.20% to 1.55%. Its grade is “Y40Mnâ€.
3 Free-cutting steels that contain free-cutting elements such as calcium and lead, plus the free-cutting element symbol after the symbol "Y" and Arabic numerals. For example: "Y15Pb", "Y45Ca".
(6) Non-quenched and tempered mechanical steel grades are indicated in non-quenched and tempered mechanical structural steels. Symbols "YF" and "F" in the brand name denote free-cutting non-quenched and tempered mechanical structural steels and non-finishing machinery for hot forging Structural steels, grades indicate that the method is the same as the alloy structural steel. For example: "YF35V", "F45V".
(7) Tool Steel Grades Tool Steels are classified into three categories: carbon tool steels, alloy tool steels, and high-speed tool steels.
1 Carbon tool steels are represented by standard chemical element symbols, symbols specified in Table 1, and Arabic numerals. Arabic numerals represent the average carbon content (in parts per thousand).
a. Ordinary manganese-containing carbon tool steel, after the tool steel symbol "T", is an Arabic numeral. For example, a carbon tool steel with an average carbon content of 0.80% is graded as "T8".
b. Higher carbon content of the carbon tool steel, plus the manganese element symbol after the tool steel symbol "T" and Arabic numerals. For example: "T8Mn".
c. High quality carbon tool steel, add "A" to the end of the grade. For example: "T8MnA".
2 alloy tool steel and high speed tool steel
Alloy tool steel and high-speed tool steel grades are indicated in the same way as alloy structural steel grades. The standard alloy elements and Arabic numerals are used, but the average carbon content is not generally specified. For example, the average carbon content is 1.60%, and the chromium, molybdenum, and vanadium contents are 11.75%, 0.50%, and 0.22%, respectively. The alloy tool steel is graded as “Cr12MoVâ€; the average carbon content is 0.85%, and the high-speed tool steels containing tungsten, molybdenum, chromium, and vanadium contents of 6.00%, 5.00%, 4.00%, and 2.00%, respectively, are indicated by their grades. It is "W6Mo5Cr4V2".
If the average carbon content is less than 1.00%, an Arabic numeral can be used to indicate the carbon content (in parts per thousand). For example, an 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 “8MnSiâ€.
Low-chromium (average chromium content <1.00%) alloy tool steel with a number “0†before the chromium content (in parts per thousand). For example, an alloy tool steel with an average chromium content of 0.60% is indicated by the designation “Cr06â€.
(8) Representation methods of plastic die steel grades In addition to the symbol “SM†on the head of plastic die steel grades, the remaining indication methods are the same as the high-quality carbon structural steel and alloy tool steel grades. For example: carbon plastic mold steel with an average carbon content of 0.45%, its brand name is “SM45â€; alloy plastic mold steel with average carbon content of 0.34%, chromium content of 1.70%, and molybdenum content of 0.42% Its brand name is "SM3Cr2Mo".
(9) Bearing steel number designation 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.
1 High-carbon chromium bearing steel, add “G†to the head of the brand, but do not indicate the carbon content. Chromium content is measured in parts per thousand, and other alloying elements are expressed as the alloy content of the alloy structural steel. For example, bearing steels with an average chromium content of 1â–¡50% are graded as “GCr15â€.
2 Carburizing bearing steel, the use of alloy structural steel grades, the other at the head of the symbol plus the symbol "G". For example: "G20 CrNiMo".
High quality carburized bearing steel, add "A" to the end of the grade. For example: "G20CrNiMoA".
3 High-carbon chromium stainless bearing steel and high-temperature bearing steel are indicated by the grades of stainless steel and heat-resistant steel. No "G" is added to the head of the brand. For example: high carbon chromium stainless bearing steel "9Cr18" and high temperature bearing steel "10Cr14Mo".
(10) Grades of stainless steel and heat-resisting steels The grades of stainless steel and heat-resisting steel are indicated by the standard alloy element symbols and Arabic numerals, and “Y†is added to the cut stainless steel and easily-cut heat-resistant steel.
The average carbon content (in parts per thousand) is generally represented by an Arabic numeral; when the average carbon content is ≥ 1.00%, it is represented by two Arabic numerals; when the upper limit of carbon content is < 0.10%, “Indicates the carbon content; when the upper limit of carbon content is ≤0.03% and >0.01% (ultra-low carbon), the carbon content is expressed by “03â€; when the upper limit of carbon content (upper carbon content is less than 0.01%), "01" indicates carbon content. When there is no lower limit for the carbon content, Arabic numerals are used to indicate the upper limit of carbon content.
Alloy element content is expressed in the same way as alloy structural steel. For example, stainless steel with an average carbon content of 0.20% and a chromium content of 13% is graded as “2Cr13â€; the upper limit of carbon content is 0.08%, the average chromium content is 18%, and the nickel content is 9%. Chrome-nickel stainless steel whose grade is denoted as "0Cr18Ni9"; vulcanized free-cutting chromium stainless steel with an upper limit of 0.12% and an average chromium content of 17%; its grade is denoted as "Y1Cr17"; the average carbon content is 1.10% , High-carbon chromium stainless steel with 17% chromium content, whose grade is denoted as "11Cr7"; ultra-low carbon stainless steel with an upper limit of 0.03%, average chromium content of 19%, and nickel content of 10%; The grade is denoted as "03Cr19Ni10"; the ultra-low carbon stainless steel whose upper limit of carbon content is 0.01%, the average chromium content is 19%, and the nickel content is 11% is indicated as "01Cr19Ni11".
(11) Method of indicating steel grades for welding
Welding steels include carbon steels for welding, alloy steels for welding, and stainless steels for welding. They are indicated by the designation “H†on the head of each type of welding steel. For example: "H08", "H08Mn2Si", "H1Cr18Ni9".
Premium high-quality welding steel, with the symbol "A" at the end of the grade. For example: "H08A", "08Mn2SiA".