What are the grades of steel. Explanation of symbols

Steel is the largest group of metals used, and their marking depends on the classification group.

What are the grades of steel

Decoding of the brand begins with the definition of its main group for the purpose. The following groups of steels are distinguished: structural, construction, tool, with special properties (heat-resistant, heat-resistant and high-strength).

Machine parts, rolled products, welded structures are made from structural steels . Instrumental, as the name implies, is used to manufacture a processing tool. A special type of tool steels is high-speed, they are designed for processing at higher loads. Building steels, used mainly for welded structures, have a low (up to 0.25%) carbon content. The composition is close to structural.

Structural steels

By their composition, they are divided into alloyed and carbon, that is, with special impurities and without them. Alloy steel should contain at least 45% iron. An important property is the presence of extraneous non-metallic impurities in the resulting alloy — sulfur, phosphorus, and others. The less they are contained, the better metal is considered. There are 4 quality groups in total:

At the end of the designation, the type of deoxidation of the alloy can be affixed (deoxidation is the removal of oxygen from the steel): boiling (KP), semi-quiet (PS), calm (SP). The JV index is usually not indicated.

In the general case, the decoding of steels belonging to the alloyed group can be represented as follows:

- [carbon content] [alloying elements] [deoxidation method] [additional characteristics], where the carbon content is written in hundredths of a percent.

Alloying elements are indicated as a combination of their letter designations and percentages. If the content of the element in the alloy is less than a percent, its quantity is not indicated. Currently, the following notation is used for inclusions: H - nickel, X - chromium, C - silicon, titanium - T, manganese - G, Yu - aluminum, etc. For example, 09G2S steel has 0.09% carbon, 2% manganese and silicon in an amount of about 1%. In addition, there are some additional designations of the steel grade, their interpretation is as follows:

1. "" at the beginning - bearing steel.

2. "L" at the end - foundry steel.

3. "A" at the beginning - automatic steel.

4. "E" at the beginning - electrical steel.

Separately distinguish building grades of steel. The decoding looks like this: at the beginning the letter “C” is put, after which the yield strength is indicated. The letter "K" means a variant of the chemical composition, "T" - thermal hardening.

Marking of steels with special properties is similar to marking of structural alloyed.

Tool steels

The letter “U” is placed before the designation, followed by the proportion of carbon (the minimum amount of carbon should be at least 0.7%). Tool steels, like structural steels, are divided into carbon and alloy steels, but have only 2 quality groups - high-quality and high-quality. In the second case, the letter "A" is placed in the name at the end of the designation. The letter "G" indicates an increased content of manganese. The decoding of steel grades related to tool quick cutting is somewhat different. In the first place is the designation of the entire group - the letter "P" (from the English term "rapid" - fast), then the amount of the main alloying component - tungsten (its letter designation is omitted) is indicated.

Indication of the method of steel production

For high-quality alloys, the method of production of the steel grade is indicated at the end of the designation, a description of the manufacturing methods is presented below. These codes are placed at the end of the designation: VD - vacuum-arc; - electroslag; EL - electron beam; VI - vacuum induction.