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main body: 

  Part I: the steel product label representation method According to the national standard GB221-79 "steel product label representation method" in the requirements: the name of the product label, using Chinese pinyin letters, chemical element symbols and Arabic numerals combined method. In GB221-79 "The Method of steel Product label", the high quality carbon structural steel with high manganese content is marked with the manganese element symbol after Arabic numerals. For example, sedative steel with an average carbon content of 0.50% and manganese content of 0.70-1.0-1.00%, whose grade is indicated as "50 Mn". The replacement version of the above standard is GB221-2000 "Steel product Brand presentation Method", which changes the designation of carbon structural steel, low alloy high strength structural steel and related special steel, and the designation of some other products, such as stainless steel, heat resistant steel and cold rolled silicon steel has also been modified. In GB221-2000 "The Method of Steel Product Brand", the Chinese character for carbon structural steel and low alloy high strength structural steel is the "bend" representing yield strength, the Chinese pinyin is "QU", and the symbol is the capital letter "Q". Delivery point value (in Mpa) and quality grade, deoxy method and other symbols, and form signs in order. For example: carbon structural steel is: Q235AF, Q235BZ; low alloy high strength  steel is: Q345C, Q345D.

  Part two: the structure with the steel naming representation method Combined with the above summary of the designation method of steel products, continue to describe the evolution of the naming method in low alloy structural steel. In the standard GBT 1591-88 "Low Alloy Structural Steel", the name of metal grade is consistent with GB221-79 "Steel Product Grade presentation Method", and metals with carbon content of 0.12-0.20% and manganese content of 1.20-1.60% are named 16 Mn. The following metal names for the structural steel will be used as the protagonist of the brand changes. The alternative version of the above standard is GBT 1591-94 Low Alloy High Strength Structural Steel, where the grade of steel is arranged by three parts: the Chinese pinyin letter (Q), the yield point value, and the quality level symbol (A, B, C, D, E). For example: Q390A. In this version of the standard GBT

The alternative version of the above standard is GBT 1591-2018 "Low alloy High Strength Structural Steel", and the naming method of the metal brand is consistent with GBT 1591-2008 "Low alloy High Strength Structural Steel". With the adjustment of the chemical composition of the protagonist, the improvement of the manufacturing process and other changes. The chemical composition of the protagonist, his mechanical properties, such as his elongation rate, change. In addition, the yield strength representation method was changed from lower yield strength in GBT 1591-2008 Low Alloy High Strength Structural Steel to upper yield strength in GBT 1591-2018 Low Alloy High Strength Structural Steel. Combining these changes, this version of the standard with grade steel grade Q355 for steel grade Q345. Since then, the main character's brand name Q355 has been used.

  Part three: the pressure equipment with the steel naming representation method

After a brief description of the designation evolution of structural carbon steel, the designation of pressure vessel carbon steel and low alloy steel forgings was described. In the standard JB 4726-2000 "Carbon Steel and Low Alloy Steel Forgings for Pressure Vessel", the name of metal steel number is consistent with GB221-79 "Steel Product Brand Method", and the metal steel number with 0.12-0.20% carbon content and 1.20-1.60% manganese content is named 16 Mn.

The substitute version of the above standard is NB / T 47008-2010 "Carbon Steel and alloy Steel Forgings for Pressure Equipment". The naming method of metal steel number is consistent with JB 4726-2000 "Carbon Steel and Low alloy Steel Forgings for Pressure Vessel", and the steel number is 16 Mn.

The substitute version of the above standard is NB / T 47008-2017 "Carbon Steel and alloy Steel Forgings for Pressure Equipment", the naming method of metal grade is consistent with NB / T 47008-2010 "Carbon Steel and alloy Steel Forgings for Pressure Equipment", and the metal material grade is still 16 Mn.

  Part four: comparative examples

It should be noted that in the second and third parts of this paper, the steel number of 16 Mn is only in the structural steel part, which is called the "protagonist" in this paper. This name is not used in the part of the pressure equipment, but "16 Mn" is always used. As one of the composition of this paper, take the name "16 Mn" with the same steel number and grade plate in GBT 1591-88 and NB / T 47008-2017 "Carbon Steel and alloy Steel for Pressure Equipment" as a comparison, for example, if the steel number and grade number are only specified and the implementation standard and its version are not clearly specified, it may not only cause trouble, but may even lead to the wrong use of the material and then lead to the risk of failure of the equipment during the service.

In the following two figures, the labels and materials are 16 Mn, but they have not only different manufacturing methods, but also have different requirements for mechanical properties, especially impact performance.

  Figure 1: Screenshot from GBT 1591-88, Low Alloy Structural Steel

Figure 2: Screenshot from NB / T 47008-2017 Carbon Steel and Alloy Steel Forgings for Pressure Equipment

tag:

  Different standards of the named steel number & grade & material grade of the same metal, and the same standard in different versions of the same or similar metal, its chemical composition, mechanical properties and other data are not necessarily the same. In order to avoid possible troubles, the grade of metal materials mentioned in the contract or technical documents shall be complete, including the standard number, version, delivery status, etc.

Hammerchiae note:

  Except for the letter Q, yield strength, and quality grade. The steel number may also include the delivery status, the deoxygenation mode, etc. No relevant description was given in this article.

The main body of this paper is divided into four parts: 1. The evolution process of the marking method of steel products; 2. the evolution process of structural steel & steel grade; 3. the evolution process of steel & metal grade of steel for pressure equipment; 4. The comparison of "16 Mn and 16 Mn" in different standards, indicating that the metal products with the same steel number & grade & material grade may not refer to the only, or even quite different.