关于我国钢号表示方法概述
Modern steel products are usually labeled with a number to indicate their steel grade or type. This is because different steel grades have different properties and applications. This number is commonly known as the Steel Number or Steel Code.
In China, steel designation is based on the BOF (Basic Oxygen Furnace) or EAF (Electric Arc Furnace) method of steel manufacture. Steel grades are further designated with a four-digit number following the GB (GOST), YB (YB/T), or any other individual national standards.
The first digital of the steel number indicates the steel’s type, while the other three indicate its grade.
The first digit of the steel grade indicates the alloying elements. The second digit indicates the impact strength of the steel and the last two digits show the yield strength in MPa (Mega Pascal).
For instance, 20Mn (H) or 25Mn (H) are carbon steel used in cold drawn bars for general engineering purposes. Both have high yield points of about 270 MPa, which allows for the addition of alloying elements such as Mn, Si, and Cr. These steel grades are often used in the production of axles, crankshafts, and other parts.
Another example is 30Mn (H) steel, which is used in machinery and tools. It is stronger than 20Mn (H) and 25Mn (H) steel, with a yield of up to 350MPa and a hardness of around 24HRC (Rockwell Hardness). This type of steel is primarily used in the production of drills, drills, and other tools that require high strength and durability.
The fourth digit of the steel number may also be used to indicate the amount of alloying elements present, such as manganese, chromium, nickel, and other elements. For instance, 40Mn is low-carbon steel which contains almost no alloying elements. While 40Cr contains 0.4% chromium, 40Mn2 contains 0.2% manganese, and 40Ni3 contains 0.3% nickel.
Steel numbers can be written in either numerical or alphabetical order, depending on the system that the manufacturer is using. For example, 20Mn (H) is usually written in numerical order as 20MnH, while 40Cr is usually written in alphabetical order as 40Cr.
The Chinese steel designation system is a great tool for identifying different steel grades and their properties. Understanding this system can help manufacturers and steel purchasers choose the right steel grade for their application. Steel numbers can also help buyers and sellers quickly identify what kind of steel they are dealing with.
