08 transcript. Steel marking according to Russian, European and American systems

Steel is a metal in which various elements are joined. The dominant ones are iron and carbon. Additional components (Si, P, Mn and S) are added to the structure of such an alloy to increase the coefficient of its physical, technological, chemical and mechanical data. This metal has a fairly large output, but at the same time, a relatively low cost.

Constant improvement of the manufacturing procedure for such material guarantees the uninterrupted operation of equipment produced from it that operates under high loads.

Steel classification

Based on the characteristics of certain parameters, this material can be divided into separate varieties.

Chemical composition

Here it is customary to distinguish 3 varieties. The main difference between them is the percentage of such a substance as carbon (C) in them. Thus, according to GOST 380-71 and 1050-75, the following are distinguished:

The first type can be easily subjected to gas and electric welding. If you increase the level of C concentration in a given metal, its strength will increase. Accordingly, it is more susceptible to deformation.

In addition to the above varieties of steel, its alloyed versions are also widely used. In this case, the metal composition is supplemented by Si, Mo, Ni, Cr, Mn, W, V and Ti. This is done in order to increase the strength coefficient of products made from such an alloy. Depending on the degree of saturation with impurities, such steel grades are divided:

Purpose

By this indicator It is customary to distinguish several types of steel:

• instrumental. It corresponds to the specific purpose of the manufactured products: hot or cold forged, cutting or measuring. This type of metal is widely used in the production of machine structures;
• structural. This steel is widely used to form various devices and equipment. Thus, the alloy can be cemented, improved, spring-spring or high-strength;
• special purpose. This includes stainless steel, as well as alloys with increased strength and resistance to heat, heat-resistant and electrical steel.

Structure

Based on this characteristic, there are 2 main types of steel:

• in a state of balance;
• normalized.

Based on the structural indicators of the alloy, it can be classified as austenitic, cementite, ledeburite, pearlite, ferritic and other types.

Production quality level

In accordance with the characteristics of the steel manufacturing process: manufacturability, uniformity of structure, chemical and physical characteristics, the percentage of saturation of the composition with additional elements (P and S) and gases, the material is classified into one of 4 groups:

The first of the above groups can also be divided into 3 subgroups that are directly dependent on metal supplies:

1. “A” – in this case, phosphorus and carbon indicators are overestimated. Thus, the supply of an alloy of this subgroup is carried out according to mechanical characteristics;
2. "B". Unlike “A”, the chemical composition plays the main role here;
3. "IN". A combined subgroup, representing both the first and second options.

Deoxidation index

This process is a procedure for removing oxygen from a metal that is in a liquid state. According to this indicator, it is customary to distinguish 3 types of this material:

• calm. In this case, the process is carried out thanks to the participation of aluminum, silicon and manganese. This type has the designation “sp”;
• semi-quiet - a link located between the first and third varieties. Species marking: “ps”;
• boiling. This type of steel is characterized by a reduced level of deoxidation. It is spelled "kp".

An increase in the strength coefficient of the metal is achieved by heating it under the influence of maximum high temperatures. Due to such external influence, steel ceases to be viscous and ductile. Under this condition, the possibility of an easier process of cutting the material disappears.

Marking of steel types according to international standards

In some countries, it is customary to use their own rules for marking steel.

System used in the Russian Federation

For each separate group of the above material, its own special abbreviation is used:

1. Ordinary quality. Steels of this group are written with the letters “St”, to which is added the number of its marking (0-6), corresponding to the mechanical and chemical characteristics of the declared alloy. The higher the strength coefficient and percentage C of the metal, the higher the corresponding figure is indicated. The indication of the symbol “G” after the marking indicates an increased presence of manganese impurities in this alloy. Usually the corresponding group is written before the marking number, with the exception of “A”. The material quality category is added to the end of the digital designation of the brand. Category No. 1 is not displayed. Example: St1kp2 - supplies of this carbon steel with an ordinary level of quality are carried out according to its mechanical characteristics. It is boiling, strength marking is 1, the alloy belongs to the second category of group A.
2. High quality steel. First of all, a marking is indicated indicating its percentage carbon saturation. In cases in which this indicator does not cross the threshold of 0.65%, the last 2 digits after the decimal point of the percentage value (“05kp” is carbon boiling quality steel, with a carbon content of 0.05%) are taken to indicate its grade. In the case when the steel belongs to the industrial group (symbol “U”), to indicate the content of C in this metal, take the tenth part indicated after the decimal point (“U7” - tool steel, mild, high-quality, carbon. Its composition is 0, 7% carbon). Alloying components of the metal are written in Russian letters. In cases where it is necessary to indicate their percentage, the required figure is written after it. If it is not there, then it is conventionally considered that the alloy element in the steel composition varies in the range of 0.8-1.5% (with the exception of boron, molybdenum and vanadium). Example: “14G2” – calm, high-quality, low-alloy steel. It contains 14% C and less than 2% manganese.

High and especially high quality steels. Their marking is carried out in the same way as the previous group. The only difference is that at the end of it, for a high-quality alloy, the symbol “A” is written (indicating the presence of a nitrogen compound in the steel), and for a particularly high-quality metal – “Ш”. Example: “U8A” – high quality carbon tool steel with a C content of 0.8%.

Marking of other types of steel

It is done as follows:

• ball bearing alloys are assigned the symbol “ШХ”, after which tenths of the percentage of chromium content are prescribed;
• automatic steels are marked with the letter “A” indicating hundredths of the percentage of carbon;
• high-speed. Their designation is in the form of the symbol “P” with the corresponding figure (up to a whole number) of the content of tungsten impurities in a given metal;
• non-alloy steels of the structural group, used to create containers capable of withstanding increased levels of pressure, according to GOST 5520-79 are designated “K”;
• In the digital designation of alloy structural steel, it is customary to display the amount of chemical additive in it. This number will not be indicated if the content of such impurities does not exceed 1.5%. Letter symbols – “A”, “W”.
• “L” – cast steel;

• “C” – construction steel.

Steel designation in other countries

In the United States, various methods of marking steel alloys are used: ASME, AWS, ACJ, ASTM, AJS, ANSI, AMS, SAE and AISI. The last of these systems also applies to Europe. It is used to designate stainless steels. In accordance with AISI, the alloy is marked with three numbers (with rare exceptions, alphabetic symbols are written after them). The 1st is the metal class, and the next two are the numbering of the material in order in a certain group. Moreover, if 2 or 3 is written in place of the first digit, then this is an austenitic type of steel, and if 4, then it is martensitic or ferritic. Alphabetic characters can mean the following:

• “F” – high level of concentration of S and P impurities;
• “N” – indicates the presence of N;
• “S” – carbon content does not exceed 0.08%;
• “LN” – minimum carbon concentration supplemented with nitrogen;
• “Se”, “Cu”, “B” - the designation indicates the presence of selenium, copper or silicon in the metal;
• “L” – mass fraction of C does not exceed 0.03%.

EN is also considered the European steel designation system. Its main difference from Russian labeling is that initially all alloying elements are listed, and then their mass fraction is written down in numbers. The 1st digit is hundredths of the percentage of carbon in steel. Sometimes the symbol “X” is indicated in front of it, indicating that the metal contains more than 5% of at least one alloying component.

For Japan, it is typical to indicate the steel group in the form of alphabetic symbols, and in the form of numbers - the sequential number in a certain group with its parameters.

Due to the lack of a unified steel designation system on the market, difficulties often arise. A table is widely available that helps you easily compare the labeling of different countries.

Types and designation of cast iron

This material is a compound of C and Fe, with the content of the first element exceeding 2.14%. Cast iron is characterized by the presence of elements in the form of impurities absolutely identical to those contained in steel.

The division into types of a given metal is made taking into account the state of the carbon present in it:

In addition to letter symbols, cast iron is designated by 2 numbers, characterizing the minimum tensile strength δv in tension in MPa -10.

Steel is a product of ferrous metallurgy, the main one. It is used to produce construction fittings, rolled metal of various profiles, pipes, parts, mechanisms and tools.

Steel production

Ferrous metallurgy also deals with steel. Cast iron is a hard, but not durable material. Steel is strong, reliable, ductile, prone to be used in foundry, rolling, forging and stamping.

There are several ways to smelt steel:

1. Converter. Equipment: Batch (raw materials): scrap steel, limestone. Only carbon steels are produced.
2. Martenovsky. Equipment: open hearth furnace. Charge: liquid iron, scrap steel, iron ore. Universal for both carbon and alloy steels.
3. Electric arc. Equipment: electric arc furnace. Charge: scrap steel, cast iron, coke, limestone. Universal method.
4. Induction. Equipment: induction furnace. Charge: steel and cast iron scrap, ferroalloys.

The essence of the steel production process is to reduce the amount of negative chemical inclusions in order to obtain a metal that is popularly called “iron”, or more precisely, an iron-carbon alloy with a carbon content of no more than 2.14%.

Deoxidation processes

At the final stage of smelting, steel is characterized by a boiling process, which is influenced by the nitrogen, hydrogen, and carbon oxides inherent in it. Such an alloy in the solidified state has a porous structure, which is removed by rolling. It is soft and flexible, but not strong enough.

The deoxidation process consists of deactivating boiling impurities by introducing ferromanganese, ferrosilicon, and aluminum into the alloy. Depending on the amount of residual gases and deoxidizing elements, the steel can be semi-quiet or calm.

Finished steel of the required degree of deoxidation is poured into molds for crystallization and use in subsequent technological stages of manufacturing finished steel products.

Carbon steel classification

All steel existing on the world market can be divided into carbon and alloy. All grades of carbon steel are divided into different classifier groups and designation features.

Based on the main classification characteristics, the following are distinguished:

1. Carbon structural steels. They contain less than 0.8% carbon. They are used for the manufacture of fittings, rolled products and castings.
2. Carbon tool steels that contain carbon in an amount from 0.7% to 1.3%. They are used for tools and instrument equipment.

By deoxidation methods:

• boiling - deoxidizing elements (DE) in the composition of less than 0.05%;
• semi-quiet - 0.05%≤RE≤0.15%;
• calm - 0.15%≤RE≤0.3%.

By chemical composition:

• low-carbon (0.3%≤С);
• medium carbon (0.3≤С≤0.65%);
• high-carbon (0.65≤С≤1.3%).

Depending on the microstructure:

• hypoeutectoid - such steel contains less than 0.8% carbon in its composition;
• eutectoid - these are steels with a carbon content of 0.8%;
• hypereutectoid - steels with a carbon content of over 0.8%.

By quality:

1. Regular quality. Sulfur here contains less than 0.06%, phosphorus - no more than 0.07%.
2. High quality steel. They do not contain sulfur and phosphorus more than 0.04%.
3. High quality. The amount of sulfur here does not exceed 0.025%, and phosphorus - no more than 0.018%.

According to the main standard, carbon steel grades are divided into:

• structural ones of ordinary quality;
• structural quality;
• instrumental qualitative;
• instrumental high quality.

Features of marking of structural steel of ordinary quality

Ordinary quality steels contain: C - up to 0.6%, S - up to 0.06%, P - up to 0.07%. Let's look at how this carbon steel is marked. GOST 380 defines the following designation nuances:

• A, B, C - group; A - not indicated in stamps;
• 0-6 after the letters “St” - a serial number in which the chemical composition and (or) mechanical properties are encrypted;
• G - presence of Mangan Mn (manganese);
• kp, ps, sp - degree of deoxidation (boiling, semi-calm, calm).

The numbers from 1 to 6 after indicating the degree of deoxidation through a dash are categories. However, the first category is not designated in any way.

The letters M, K at the beginning of the brand can mean a metallurgical production method: open-hearth or oxygen-converter. By the way, carbon steels of ordinary quality are represented by a quantitative composition of grades, approximately 47 pieces.

Classification of structural steels of ordinary quality

Carbon steels of ordinary quality are divided into groups.

• Group A: steels that must precisely meet specified mechanical properties. They are supplied to the consumer most often in the form of sheet and multi-profile products (sheets, T-bars, I-beams, fittings, rivets and housings). Brands: St0, St1 - St6 (kp, ps, sp), categories 1-3, including St3Gps, St5Gps.
• Group B: steels that must be regulated by the required chemical composition and properties. Castings and rolled products are produced, which will be subjected to additional machining by pressure in a hot state (forging, stamping). Brands: BSt0, BSt1 (kp-sp), BSt2 (kp, ps), BSt3 (kp-sp, including BSt3Gps), BSt4 (kp, ps), BSt 6 (ps, sp), categories 1 and 2.
• Group B: steels that must meet the required chemical, physical, mechanical and technological properties. This group is characterized by a variety of grades from which ductile sheet metal is made, durable fittings for working in areas of significant temperature changes, and critical parts (bolts, nuts, axles, piston pins). All products of various compositions, properties and brands of this group are united by good technological weldability. Brands: VSt1-VSt6 (kp, ps, sp), VSt5 (ps, sp), including VSt3Gps, categories 1-6.

Structural steels of ordinary quality are alloys that have a wide variety of uses in industry.

Carbon Quality Steel Marking

High-quality carbon steels contain no more than 0.04% S and P, respectively.

Marking (GOST 1050-88):

• numbers 05-60 - encrypted presence of carbon (minimum - 0.05%, maximum - 0.6%);
• kp, ps, sp - degree of deoxidation (“sp” is not indicated);
• G, Yu, F - contain manganese, aluminum, vanadium.

Labeling exceptions

Carbon quality steels have exceptions in their markings:

• 15K, 20K, 22K - high-quality steels, applicable in boiler making;
• 20-PV - carbon - 0.2%, steel is applicable in the manufacture of pipes by hot rolling, in boiler building and installation of heating systems, contains copper and chromium;
• OSV - steel for the manufacture of carriage axles, contains nickel, chromium, copper.

All grades of high-quality steel are characterized by the possible need to use thermal (for example, normalization) and chemical-thermal treatment (for example, carburization).

Classification of carbon quality steels

This type of carbon steel can be divided into 4 groups:

1. Highly plastic material, suitable for cold machining (rolling), sheet and tube products. Grades - steel 08ps, steel 08, steel 08kp.
2. A metal used in hot rolling and stamping that will operate under thermally aggressive conditions. Grades - from steel 10 to steel 25.
3. Steel that has found application in the manufacture of critical parts, including springs, leaf springs, couplings, bolts, and shafts. Grades - from steel 60 to steel 85.
4. Steels that require reliable operation in aggressive conditions (for example, the chain of a caterpillar tractor). Grades steel 30, steel 50, steel 30G, steel 50G.

It is also possible to divide into 2 groups all known grades of carbon steel from the quality class: conventional structural steel and manganese-containing structural steel.

Applications of Carbon Structural Steel

Carbon tool steels are characterized by high strength and toughness. They must undergo multi-stage heat treatment.

Brand designation (GOST 1435-74):

• U - carbon instrumental;
• 7 -13 - carbon content in it is 0.7-1.3%, respectively;
• G - presence of manganese in the composition;
• A - high quality.

Exceptions to the basic principles of marking carbon tool steels are the material for watch movement parts A75, ASU10E, AU10E.

Requirements for carbon tool steels

In accordance with GOST, tool steels must meet a number of characteristics.

Necessary physical, chemical and mechanical properties: quality indicators of hardness, impact strength, strength, resistance to temperature changes during operation (during cutting, drilling, shock loads), corrosion resistance.

Specified technological properties:

• resistance to negative processes of cutting technology (chip adhesion, hardening);
• good machinability by turning and grinding;
• flexibility to heat treatment;
• resistance to overheating.

To improve the quality of mechanical and technological parameters, tool steels are subjected to multi-stage heat treatment:

• annealing of the starting material before making tools;
• hardening (cooling in salt solutions) and subsequent tempering of finished products (mainly low tempering).

The resulting properties are determined by the chemical composition and the resulting microstructure: martensite with cementite and austenite inclusions.

Use of carbon tool steels

The described steels are used for the manufacture of all kinds of tools: cutting, impact, auxiliary.

• Steel U7, U7A - hammers, chisels, axes, chisels, sledgehammers, chisels, fishhooks.
• Steel U8, U8A, U8G - saws, screwdrivers, punches, countersinks, cutters, pliers.
• Steel U9, U9A - metalworking tools, tools for cutting wood.
• U11, U11A - rasps, taps, auxiliary tools for stamping and calibration.
• U 12, U12A - reamers, taps, measuring tools.
• U13, U13A - files, razor and surgical instruments, stamping punches.

A rational choice of carbon steel grade, its heat treatment technology, an understanding of its properties and features is the key to long service life of manufactured, processed or used structures or tools.

Steel grade: 08ps (replacement: 08).

Class: high-quality carbon structural steel.

Industrial use: for gaskets, washers, forks, pipes, as well as parts subjected to chemical-thermal treatment - bushings, eyes, rods.

Hardness: HB 10 -1 = 131 MPa

Weldability of material: without restrictions, except for chemically and thermally treated parts; welding methods: RDS, ADS submerged arc with gas protection, KTS.

Forging temperature, o C: beginning 1250, end 800. Workpieces with a cross-section of up to 300 mm are cooled in air.

Flock Sensitivity: not sensitive.

Tendency to temper brittleness: not inclined.

Type of delivery:

• Long products, including shaped steel: GOST 2590-2006, GOST 2879-2006, GOST 8509-93, GOST 10702-78.
• Calibrated rod GOST 7417-75, GOST 8560-78, GOST 10702-78.
• Polished rod and silver steel GOST 10702-78, GOST 14955-77.
• Thin sheet GOST 16523-97, GOST 19903-74, GOST 19904-90, GOST 9045-93.
• Tape GOST 503-81, GOST 10234-77.
• Strip GOST 1577-93, GOST 82-70.
• Pipes GOST 10704-91, GOST 10705-80.
• Thick sheet GOST 4041-71, GOST 19903-74, GOST 1577-93.

Steel 08ps

Our website presents a variety of metal products that can be purchased to order in any quantity. Also on the Atlant Metal portal you will find a lot of useful information about various products, compositions and grades of steel. From this article you will learn facts about steel grade 08ps, which is a high-quality structural carbon steel. On our website it is easy to order products made from this material, as well as from steel grades 08ps5 and 08ps6.

In the name St08ps “St” is steel. The numbers that follow conventionally indicate the amount of carbon in the composition (in percent, in tenths)

The “PS” in the name stands for semi-tempered steel, one of three methods for deoxidizing steel. There is also boiling and calm.

Steel 08ps and its characteristics

This grade can be replaced with steel 08.

St08ps is widely used in industry. Various elements are made from it, which will subsequently experience chemical and thermal effects, for example, cylindrical parts with an axial hole, parts with a regular hole, suspension parts. Also, the characteristics of 08ps allow this steel to be used to create gaskets, fasteners, forks, and pipes.

For welding, the methods used are manual arc welding, submerged argon arc welding (gas protection required), and resistance spot welding. There are no restrictions on weldability. The only exception is elements subjected to chemical and thermal treatment.

Hardness of steel St08ps: HB 10 -1 = 131 MPa. The material is not sensitive to flakes. Not prone to temper brittleness.

If you are going to forge a product from this material, you must first work at a temperature of 1,250 degrees Celsius. In the end, it should drop to 800. Objects with a cross-section of up to 300 millimeters can be cooled in air.

Products made from steel grade 08ps

We offer you to purchase long and shaped rolled products, which are made from this material. Find out more details from our managers.

This steel is used to create rods with various types of surface treatment, silver, strips and tapes, metal sheets of different thicknesses.

Structural carbon steels have become quite widespread and can be used to produce high-strength load-bearing elements. An example is steel 08PS. It is characterized by high performance characteristics, which can be improved by heat treatment.

Chemical composition and characteristics

The quantity of all elements in the composition is regulated by GOST 1050-88. That is why only the mass fraction of carbon is indicated when labeling. The composition is as follows:

1. The carbon concentration can vary from 0.05% to 0.11%. This element determines the hardness of the surface layer and the strength of the structure, as well as the degree of weldability of 08PS. During heat treatment, the structure is rebuilt, becoming more dense.
2. Silicon is also added to the composition, the mass fraction of which is from 0.05% to 0.17%. It also defines the main characteristics of 08PS.
3. Manganese is also considered a major chemical, with about 0.35-0.65%.
4. Chromium is usually included in the composition to provide corrosion resistance. Carbon structural steel, during long-term operation at high humidity, becomes covered with corrosion due to the low concentration of the alloying substance in question, the mass fraction is 0.1%.

Download GOST 1050-88

The chemical composition of 08PS steel is characterized by the presence of harmful chemical elements sulfur and phosphorus, an increase in the concentration of which leads to a decrease in the strength and hardness of the surface.

In general, steel grade 08PS shows good strength characteristics and hardness.

Its advantages include the following:

1. When using a similar brand, the created load-bearing elements can withstand various loads. If the applied load is maintained within the required range, then the manufactured parts retain their shape.
2. The yield strength is quite high, due to which the metal can withstand elastic deformation.
3. Grade 08PS is characterized by high weldability. A variety of technologies can be used to carry out welding operations. However, after heat treatment it will not be possible to weld the elements, which is due to the saturation of the surface layer with carbon. This substance significantly reduces the degree of weldability of the material.

If necessary, the performance characteristics of the metal can be significantly improved by heat treatment.

Among the features of its implementation, the following points can be noted:

1. When heat treated, there is no need to add other chemicals to improve performance.
2. After hardening, the strength of the melt increases significantly. Often such processing is carried out to obtain load-bearing structures that are designed to withstand high loads.
3. The most common types of heat treatment are hardening, tempering and annealing. Tempering is carried out to eliminate stresses that arise inside the alloy. Annealing aligns the internal structure and eliminates too high ductility of the 08PS alloy.
4. Attention is paid to how the workpiece is cooled. Oil or water can be used for this. It is worth considering that oil significantly improves the quality of the metal and eliminates the possibility of serious defects due to uneven cooling.

To perform heat treatment, special equipment is required that can heat the alloy to the desired temperature and maintain it for the required period.

Decoding

When marking, certain standards may be applied that allow one to determine the basic performance characteristics of the metal. Steel 08PS (GOST is used to designate metal produced in the CIS countries) is deciphered as follows:

1. 08 indicates the amount of carbon - 0.8%. The main qualities of 08PS depend specifically on this chemical element. Therefore, it is indicated when marking the material
2. SP indicates the degree of deoxidation of the alloy; in the case under consideration, it is semi-calm.

St08PS stands for structural carbon metal. It can be characterized by three degrees of deoxidation. Semi-quiet metal, which is characterized by the positive qualities of boiling and calm alloys, has become quite widespread. Decoding in this case does not allow determining the concentration of other chemicals; their quantity is regulated by GOST.

Purpose and application of steel 08PS

Carbon steel 08 PS is characterized by properties that determine an extremely wide range of its application. Grade 08PS can be used in the manufacture of the following parts:

1. Washers.
2. Forks.
3. Pipes for various purposes.

The most varied types of blanks are available for sale. An example is rods and shaped, long products. In addition, sheets and strips are supplied to production sites.

You may also be interested in the following articles:

Steel 35 structural carbon quality
Steel 10 (carbon quality)

Any specialist who deals with metal is familiar with the concept of “steel grade”. Deciphering the markings of steel alloys makes it possible to get an idea of ​​their chemical composition and physical characteristics. Understanding this marking, despite its apparent complexity, is quite simple - it is only important to know on what principle it is compiled.

The alloy is designated by letters and numbers, which can be used to accurately determine which chemical elements it contains and in what quantities. Knowing this, as well as how each of these elements can affect the finished alloy, it is possible to determine with a high degree of probability exactly what technical characteristics are characteristic of a particular grade of steel.

Types of steels and features of their markings

Steel is an alloy of iron and carbon, the content of the latter in it being no more than 2.14%. Carbon gives the alloy hardness, but if it is in excess, the metal becomes too brittle.

One of the most important parameters by which steels are divided into different classes is the chemical composition. Among the steels according to this criterion, alloyed and carbon steels are distinguished, the latter are divided into low-carbon (carbon up to 0.25%), medium-carbon (0.25–0.6%) and high-carbon (they contain more than 0.6% carbon).

By including alloying elements in the steel, it can be given the required characteristics. It is in this way that, by combining the type and quantitative content of additives, grades with improved mechanical properties, corrosion resistance, magnetic and electrical characteristics are obtained. Of course, it is possible to improve the characteristics of steels using heat treatment, but alloying additives make it possible to do this more effectively.

Based on the quantitative composition of alloying elements, low-, medium- and high-alloy alloys are distinguished. In the first alloying elements there is no more than 2.5%, in medium alloyed elements - 2.5–10%, in highly alloyed ones - more than 10%.

Steels are classified according to their purpose. Thus, there are instrumental and structural types, grades distinguished by special physical properties. Tool types are used for the production of stamping, measuring, and cutting tools, structural ones - for the production of products used in construction and mechanical engineering. Alloys with special physical properties (also called precision) are used to make products that must have special characteristics (magnetic, strength, etc.).

Steels are also contrasted with each other based on their special chemical properties. Alloys of this group include stainless, scale-resistant, heat-resistant, etc. Typically, they can be corrosion-resistant and are different categories.

In addition to useful elements, steel also contains harmful impurities, the main ones of which are sulfur and phosphorus. It also contains gases in an unbound state (oxygen and nitrogen), which negatively affects its characteristics.

If we consider the main harmful impurities, phosphorus increases the brittleness of the alloy, which is especially pronounced at low temperatures (the so-called cold brittleness), and sulfur causes cracks in metal heated to high temperatures (red brittleness). Phosphorus, among other things, significantly reduces the ductility of heated metal. Based on the quantitative content of these two elements, steels are divided into ordinary quality (no more than 0.06–0.07% sulfur and phosphorus), high-quality (up to 0.035%), high-quality (up to 0.025%) and especially high-quality (sulfur - up to 0.015%, phosphorus - up to 0.02%).

The marking of steels also indicates to what extent oxygen has been removed from their composition. According to the level of deoxidation, steels are divided into:

• calm type, designated by the letter combination “SP”;
• semi-calm - “PS”;
• boiling - “KP”.

What does the steel marking mean?

It has become quite easy to decipher the brand; you just need to have certain information. Structural steels of ordinary quality and not containing alloying elements are marked with the letter combination “St”. By the number following the letters in the name of the brand, you can determine how much carbon is in such an alloy (calculated in tenths of a percent). The numbers may be followed by the letters “KP”: from them it becomes clear that this alloy has not completely gone through the deoxidation process in the furnace, and accordingly, it belongs to the boiling category. If the brand name does not contain such letters, then the steel corresponds to the calm category.

Structural, belonging to the category of quality, has two numbers in its designation; they are used to determine the average carbon content in it (calculated in hundredths of a percent).

Before we begin to consider the grades of those steels that include alloying additives, you should understand how these additives are designated. Marking of alloy steels may include the following letter designations:

Designation of steels with alloying elements

As mentioned above, the classification of steels with alloying elements includes several categories. The marking of alloy steels is compiled according to certain rules, knowledge of which allows one to quite simply determine the category of a particular alloy and the main area of ​​its application. In the initial part of the names of such brands there are numbers (two or one) indicating the carbon content. Two numbers indicate its average content in the alloy in hundredths of a percent, and one – in tenths. There are also steels that do not have numbers at the beginning of the brand name. This means that the carbon content in these alloys is within 1%.

The letters that can be seen behind the first digits of the brand name indicate what the alloy is made of. The letters that give information about a particular element in its composition may or may not be followed by numbers. If there is a number, then it determines (in whole percentages) the average content of the element indicated by the letter in the alloy, and if there is no number, it means that this element is contained in the range from 1 to 1.5%.

At the end of the marking of certain types of steel there may be the letter “A”. This suggests that this is high quality steel. These grades may include carbon steels and alloys with alloying additives in their composition. According to the classification, this category of steels includes those in which sulfur and phosphorus amount to no more than 0.03%.

Examples of marking steels of various types

Determining the grade of steel and assigning an alloy to a certain type is a task that should not cause any problems for a specialist. You don’t always have a table at hand that gives a breakdown of brand names, but the examples given below will help you figure it out.

Structural steels that do not contain alloying elements are designated by the letter combination “St”. The numbers following are the carbon content, calculated in hundredths of a percent. Low-alloy structural steels are marked somewhat differently. For example, 09G2S steel contains 0.09% carbon, and alloying additives (manganese, silicon, etc.) are contained within 2.5%. 10KhSND and 15KhSND, which are very similar in their markings, differ in different amounts of carbon, and the share of each alloying element in them is no more than 1%. That is why there are no numbers after the letters indicating each alloying element in such an alloy.

20Х, 30Х, 40Х, etc. – this is how structural alloy steels are marked; the predominant alloying element in them is chromium. The number at the beginning of such a mark is the carbon content in the alloy in question, calculated in hundredths of a percent. The letter designation of each alloying element can be followed by a number, which is used to determine its quantitative content in the alloy. If it is not there, then the specified element in the steel contains no more than 1.5%.

You can consider an example of the designation of chromium-silicon-manganese steel 30KhGSA. According to the labeling, it consists of carbon (0.3%), manganese, silicon, and chromium. It contains 0.8–1.1% of each of these elements.

How to decipher steel markings?

To make deciphering the designations of different types of steels easy, you should know well what they are. Certain categories of steel have special markings. They are usually designated by certain letters, which allows you to immediately understand both the purpose of the metal in question and its approximate composition. Let's look at some of these brands and understand their designation.

Structural steels specially intended for the manufacture of bearings can be recognized by the letter “Ш”; this letter is placed at the very beginning of their marking. After it in the brand name there is a letter designation of the corresponding alloying additives, as well as numbers by which the quantitative content of these additives is determined. Thus, steel grades ShKh4 and ShKh15, in addition to iron and carbon, contain chromium in amounts of 0.4 and 1.5%, respectively.

The letter “K”, which appears after the first digits in the brand name, indicating the quantitative carbon content, denotes structural non-alloy steels used for the production of vessels and steam boilers operating under high pressure (20K, 22K, etc.).

High-quality alloy steels, which have improved casting properties, can be recognized by the letter “L” at the very end of the marking (35ХМЛ, 40ХЛ, etc.).

Deciphering the grades of construction steel can cause some difficulty if you do not know the specifics of the markings. Alloys of this category are designated by the letter “C”, which is placed at the very beginning. The numbers following it indicate the minimum yield strength. These brands also use additional letter designations:

• letter T – heat-strengthened rolled products;
• letter K – steel, characterized by increased corrosion resistance;
• letter D is an alloy characterized by a high copper content (S345T, S390K, etc.).

Unalloyed steels belonging to the tool category are designated by the letter “U”; it is affixed at the beginning of their marking. The number following this letter expresses the quantitative carbon content in the alloy in question. Steels of this category can be high-quality and high-quality (they can be identified by the letter “A”, it is placed at the end of the brand name). Their marking may contain the letter “G”, which means a high content of manganese (U7, U8, U8A, U8GA, etc.).

The marking of those steels that are included in the high-speed cutting category begins with the letter “P”, followed by numbers indicating the quantitative content of tungsten. Otherwise, brands of such alloys are named according to the standard principle: letters denoting the element, and, accordingly, numbers reflecting its quantitative content. The designation of such steels does not indicate chromium, since its standard content in them is about 4%, as well as carbon, the amount of which is proportional to the vanadium content. If the amount of vanadium exceeds 2.5%, then its letter designation and quantitative content are affixed at the very end of the marking (З9, Р18, Р6М5Ф3, etc.).

Unalloyed steels belonging to the electrical category are marked in a special way (they are also often called pure technical iron). The low electrical resistance of such metals is ensured due to the fact that their composition is characterized by a minimum carbon content - less than 0.04%. There are no letters in the designation of grades of such steels, only numbers: 10880, 20880, etc. The first digit indicates the classification by type of processing: hot-rolled or forged - 1, calibrated - 2. The second digit is associated with the category of the aging coefficient: 0 - non-standardized, 1 - normalized The third digit indicates the group to which this steel belongs according to the standardized characteristic taken as the main one. The value of the standardized characteristic itself is determined from the fourth and fifth digits.

The principles by which the designation of steel alloys is carried out were developed back in the Soviet period, but to this day they are successfully used not only in Russia, but also in the CIS countries. Having information about a particular grade of steel, you can not only determine its chemical composition, but also effectively select metals with the required characteristics.