What are steel grades. Explanation of designations

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Steels are the most numerous group of metals used, and their marking depends on the classification group.

What are steel grades

Deciphering a brand begins with the definition of its main group by 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. Toolboxes, as the name implies, are used to produce a machining tool. A special type of tool steels - high-speed, they are designed for processing at higher loads. Construction steels, used mainly for welded structures, have a low (up to 0.25%) carbon content. The composition is close to structural.

Structural steels

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

Group	Maximum harmful impurities	Marking
Regular quality	0.05 %	"St" at the beginning of designation
Quality	0.035 %	"Steel" before designation; most often not written
High Quality	0.025 %	"A" at the end of designation
Extra High Quality	0.015 %	"Ш" at the end of designation

At the end of the designation, the type of alloy deoxidation can be put down (deoxidation is the removal of oxygen from the steel composition): boiling (KP), semi-quiet (PS), calm (SP). The index "SP" 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 an element in the alloy is less than a percent, its quantity is not indicated. At presenttime for inclusions, the following designations are used: H - nickel, X - chromium, C - silicon, titanium - T, manganese - G, Yu - aluminum, etc. For example, steel 09G2S contains 0.09% carbon, 2% manganese and silicon in an amount of about 1%. In addition, there are some additional steel grade designations, their decoding is as follows:

1. "Ш" 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 allocate building steel grades. The decoding looks like this: the letter "C" is placed at the beginning, after which the yield strength is indicated. The letter "K" means a variant of the chemical composition, "T" - thermal hardening.

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

Tool steels

The letter "Y" is placed before the designation, followed by the proportion of carbon (the minimum amount of carbon must be at least 0.7%). Tool steels, like structural steels, are divided into carbon and alloy steels, but they 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 high-speed cutting is somewhat different. In the first place isthe designation of the entire group is the letter "P" (from the English term "rapid" - fast), then the amount of the main alloying component - tungsten is indicated (its letter designation is omitted).

Indicating the method of steel production

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