How are alloy steels marked?

Alloy steels

Alloy steels are alloys whose properties are improved by adding additional components called alloying components. Their use is driven by the desire to achieve different properties from the resulting raw materials that are necessary in different situations.

Alloy steels

This alloy has increased strength and does not corrode longer. The areas of its application are quite diverse. Basically, these are pipes, parts and other products that will be subject to increased temperature changes during operation.

The composition of ordinary metal includes iron, carbon and various impurities. When doping, as mentioned earlier, other components are added to it, called alloying components. Among them: niobium, chromium, nickel, silicon, vanadium, etc. Aluminum and molybdenum are also often found. To increase the strength of the resulting raw material, titanium is often added.

Properties of alloy steel

Most often, its properties are determined by impurities added during production.

The qualities of steel depend on the alloying elements that are added to its composition:

• rust resistance occurs due to molybdenum and chromium;
• hardness occurs due to manganese, chromium and other components;
• strength is gained through the addition of titanium, manganese, chromium and tungsten.

Alloy steel becomes stronger and more resistant to environmental influences when it contains at least 12% chromium.

Steel, alloyed while maintaining the required percentage of all its elements, will not change its qualities up to a heating temperature of 600 degrees Celsius.

The quality of such material depends entirely on the amount of carbon in it, since this is one of the main components of its composition. It is also necessary to include iron in its composition. Nickel, chromium, copper, vanadium and other components are added to improve other properties of the raw material.

Now let’s look at how alloying elements affect the properties of the resulting raw material:

• Chromium, like nickel, is responsible for imparting rust resistance. With its help, the well-known stainless steel is obtained; the metal is made harder and stronger.
• Nickel adds not only strength, but also ductility.
• Copper, in addition to corrosion resistance, helps resist various acids.
• Vanadium compacts the structure and makes it fine-grained.
• Manganese is responsible for wear resistance.
• Tungsten maintains the hardness of the material when exposed to high temperatures.
• Silicon gives the metal its elasticity and also makes it magnetic.
• The presence of aluminum adds heat resistance to the resulting material.

How does the structure change when various impurities are added? As a result of their introduction, the crystal lattice is destroyed due to differences in the shape of electrons and atomic quantities. Therefore, the characteristics of alloy steel may fluctuate due to changes in the percentage of elements in its composition. The alloy gains hardness, strength and ductility after heat treatment.

Appearance of alloy steel

This metal usually differs in chemical composition. Therefore the classification will be as follows:

1. Low alloyed – the percentage of alloyed additives is no more than 2.5.
2. Medium alloyed - impurities are no more than 2.5-10%.
3. Highly alloyed - impurities can be more than 10% and increase to 50.

According to the classification, it is divided into: corrosion-resistant steel and heat-resistant steel (withstands above 1000 degrees).

According to chemical decomposition, the following are distinguished:

• scale-resistant (at 550 degrees);
• heat resistant.

There are two main types: alloy and carbon. Let's see what differences they have.

Carbon steel is an alloy containing, together with iron and carbon, silicon and manganese. Sulfur and phosphorus, also present in its composition, are considered negative additives, because because of them, its mechanical properties deteriorate.

Steel comes in low, medium and high carbon grades. The greater the proportion of carbon in such alloys, the less their ductility, but the harder the final material is.

Carbon steel is an alloy of iron with carbon up to 2%. Silicon, sulfur and phosphorus are also added to it. However, the main component is still carbon. The percentage of these elements is approximately the following: iron up to 99.0%, manganese - 03-0.8, sulfur up to 0.06 and silicon up to 0.15-0.35.

The main disadvantages of carbon steel:

• if it has good strength and hardness, then it lacks ductility;
• hardness and cutting ability are lost when heated to 200 degrees, and at higher temperatures strength is also lost;
• low resistance to rust when immersed in electrolyte, in aggressive environments, etc.;
• increased coefficient of thermal expansion;
• weighting of finished products;
• increase in the cost of the final product;
• difficulties in design due to the low strength of such steel.

Alloyed – steel, which, along with conventional additives, contains alloyed elements that significantly improve its quality. These are tungsten, molybdenum, nickel, etc. And also manganese and silicon in significant quantities. Impurities are added during melting. This metal is distinguished by its valuable qualities, which are absent in carbon steel, and is free from its disadvantages.

Use of alloy steel

Today it is almost impossible to name at least one sphere of human activity where there would not be a place for an alloy with such characteristics. Almost all tools are produced from structural and tool steels, for example, milling cutters, cutters, dies, etc. Stainless alloy steels are also used for the production of household products, for example, in the production of utensils and housings for household appliances.

Alloy steel also has many other qualities that guarantee its widest application. It increases the service life of a wide variety of products, ensures their reliability and even allows you to save money. After all, the longer this or that thing is used, the less often you have to purchase a new one.

By the way, products or their components made of alloyed material can be found not only in construction or mechanical engineering, but also in the hands of surgeons, for example, a scalpel, in the production of pipelines. If you make a knife from it, you won’t have to sharpen it often.

Alloy steel products

The scope of use of alloy steels is directly dependent on the heat treatment method to which it has been subjected. Previously, the classification of this material by purpose according to GOST was studied: tool, structural and steel with special qualities.

Low-alloy steels lend themselves well to welding, which is why pipes and other structures are most often made from them. Alloy tool steel is excellent as a raw material for products that will work under pressure.

According to GOST 5950-2000, alloy steel is a material for the production of medical instruments, knives, band saws, etc. This GOST includes all types of its designations and areas of use.

Stainless steel, containing a lot of chromium, is used for the production of pipe products. Pipes made from this material are characterized by increased resistance to rust, and they also perfectly withstand temperature fluctuations, especially high ones.

Marking of alloy steels

How is the marking of alloy steels deciphered? What is she talking about? According to GOST, it contains the following information: the letter deciphers the chemical element, and the number behind it indicates how much it is as a percentage. If the figure is not entered, then the percentage of a particular component is small (no more than 1%).

Various steels are classified as alloyed. As a result, the need arose to systematize their designations. This is reflected in GOST 4543-71, which states that in steel grades with special qualities, the letter should come first. It indicates that the metal, depending on its qualities, belongs to a specific group.

If the first letters are “F”, “X” or “E”, then the metal is classified as stainless with magnetic properties, or chromium. Chromium-nickel stainless steel is designated by the letter “I”. The letters “P” and “W” indicate alloys that belong to ball-bearing tool and high-speed cutting alloys.

If the steel is alloyed, then it can be either high quality or especially high quality. Then their stamp will end with the letters “A” or “W”. Ordinary steels are not designated this way.

Alloys produced by rolling also receive a special designation. Then the marking will contain the letter “N” (cold-hardened) or “TO” (heat-treated).

The ability to understand the markings will always allow you to easily and quite clearly determine the chemical composition of the presented metal, despite the fact that it is in the relevant literature. The first number is the percentage of carbon in hundredths.

Next, the number is followed by letters deciphering the alloying elements used as an impurity. Each letter indicates the amount of the named component, expressed in whole parts.

It happens that there is only a letter, which indicates the content of the element in an amount not exceeding 1.5%.

It is worth paying attention to the fact that the designation and classification of chemical elements using letters may not necessarily coincide with the initial letter in their name: aluminum (u), chromium (x), manganese (g), tungsten (v), nickel (n) , nitrogen (a), copper (d), vanadium (f), etc.

If there is a letter “A” (nitrogen) in the middle of the marking, then this indicates how much nitrogen is in the steel. If the letter “A” is at the end, then the phosphorus and sulfur in this brand are less than 0.03%, so it belongs to pure.

The double letter “A”, which appears first on the right in the designation, indicates the special purity of the material from the presence of the above components. How much sulfur it contains is also determined according to GOST. The marking may also begin with the following letters: “Ш” - ball bearing, “R” - high-speed, “E” - electrical, “A” - automatic, the letter “L” indicates that the steel was produced by casting.

Source: https://stankiexpert.ru/spravochnik/materialovedenie/legirovannye-stali.html

How are alloy steels marked?

For more than 3,000 years, humanity has been processing iron, making various tools, machines, and household utensils. Despite the relatively high mechanical properties of this metal, its destruction due to corrosion does not contribute to the long-term use of iron products in the open air.

Another significant limitation in the use of this metal is its low aesthetic qualities. To significantly improve these properties in the production of steel, additives are used that impart resistance to oxidation, the appearance of shine on its surface and a significant increase in the strength of the metal.

What is alloy steel

This is carbon steel, to improve its technological properties, special alloying elements have been introduced. The percentage of additives in the composition is small, but even with a small concentration, the physical properties of the metal improve several times.

Depending on the type of additives used in steel production, the metal acquires the following properties:

• resistance to corrosion;
• elasticity;
• infusibility;
• strength.

To impart the listed qualities, the following metals are added to the composition:

• chromium;
• nickel;
• molybdenum;
• tungsten;
• copper.

Often, it is enough to add 1 - 3% alloying elements to carbon steel to give it the necessary properties and qualities.

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Types of alloy steels

Based on the percentage of additives, steels are divided into:

1. Low alloyed - additive content less than 2.5%
2. Medium alloyed - 2.5 - 10%.
3. Highly alloyed - more than 10%.

Alloy steels are also divided into the following types:

• structural;
• instrumental;
• with special physical properties.

Structural and tool products are used in metal applications where increased strength is required. Alloy steels with special physical properties can be resistant to corrosion, high temperatures and chemically aggressive environments.

Application of alloy alloys

Due to its high performance characteristics, alloy steel is used in mechanical engineering, the manufacture of tools, pipes and building materials.

Machine parts are usually made from pearlitic metals. This category of materials includes low-alloy and medium-alloy steels, which, after annealing, have a structure that allows the metal to be easily processed using a cutting tool.

Low-alloy steels, due to their increased strength characteristics, can significantly save money during the construction of large-sized structures and machines. For example, in shipbuilding, thanks to the use of material, it is possible to reduce the thickness of the metal used.

Alloy steels with chromium additions are widely used for the production of products that are resistant to lactic and acetic acid, as well as the following parts operating under significant pressure:

1. Piston pins, universal joints and other products designed for use in conditions of increased wear.
2. Cam couplings, plungers and spline rollers.
3. Gearbox gears and worm shafts, as well as other products for low and medium speed operation.

High-alloy steel is widely used to produce parts that are resistant to corrosion. Such products are also resistant to high temperatures and can operate in conditions up to +1100 degrees.

Some types of alloys have special applications due to their special thermal properties, for example:

1. EN42 - the material has the same expansion coefficient as glass, therefore it is used as electrodes in incandescent lamps.
2. Х8Н36 - has constant elasticity, which does not change within temperature limits from minus 50 to +100 degrees.
   Due to its constant elasticity, this material is widely used for the production of springs for watch mechanisms and pointer measuring instruments.
3. I36 - the alloy has a zero coefficient of thermal expansion, so it is ideal for the manufacture of various standards and calibration products.

Welding alloy steels: features

Alloy alloys have good ductility, so complex structures can be made from them by welding. Due to the different content of additives, each type of alloyed products has its own characteristics.

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Welding low alloy steels

The peculiarity of welded joints of low-alloy steels is their high resistance to cold cracks and brittle fracture. But, such properties of the connecting seam can only be achieved with proper welding.

If the preheating process is disrupted or the weld is subjected to too rapid cooling, the metal may receive microscopic damage at the joints, which will significantly reduce the strength of the entire structure.

Low-alloy steels 10G2SD, as well as 14KhGS and 15KhSND are welded using a direct current machine with reverse polarity. Electrodes for welding must have a calcium fluoride coating.

The amount of welding current must exactly match the type of electrode, the thickness of the metal and the type of alloy.

Failure to comply with this requirement will also affect the quality of the weld and, as a result, the strength of the manufactured structure.

Welding of low-alloy steel must be carried out without interruption so that the entire seam is made without a metal temperature of at least 200 degrees. The average welding speed is 20 m/h, with a voltage of 40 V and a current of 80 A.

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Welding of medium alloy steels

When manufacturing structures from medium-alloy steels, it is necessary to use welding materials in which the content of alloying elements should be less than in the material being welded.

Only by using such materials can a seam with high resistance to deformation be achieved. If, in the manufacture of products from medium-alloy steels, the sheet thickness does not exceed 5 mm, then high quality joints can be achieved using argon arc welding.

If gas welding is used to connect parts, then acetylene mixed with oxygen should be used as a combustion source.

Welding of high alloy steels

If high-alloy steel is used for the production of metal parts, then welding equipment with minimal thermal entrainment of the material should be used. This is necessary to reduce the likelihood of metal warping during welding, due to the high content of various impurities in the metal composition.

Electric welding of high-alloy alloys is carried out using calcium fluoride coated electrodes. In this case, it is possible to achieve high levels of mechanical and chemical strength of the weld.

The use of gas welding in the manufacture of structures made of high-alloy steels is undesirable. In exceptional cases, it is possible to use gas welding to connect heat-resistant high-alloy steel sheets with a thickness of no more than 2 mm.

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Conclusion

The use of alloyed alloys in the manufacture of metal parts and structures makes it possible to give them the necessary physical qualities. When working with such metals, the designation of alloying elements in steel helps to select a workpiece with the required parameters, from which the structure will then be made.

When using such alloys, it is necessary not only to know their composition, but also the methods of joining by welding. Therefore, if you follow the recommendations outlined in this article, you can get a high-quality product with the specified parameters.

(24,50 out of 5)

Source: https://steelfactoryrus.com/kak-markiruyutsya-legirovannye-stali/

Chemical composition

The quality of such material depends entirely on the amount of carbon in it, since this is one of the main components of its composition. It is also necessary to include iron in its composition. Nickel, chromium, copper, vanadium and other components are added to improve other properties of the raw material.

Now let’s look at how alloying elements affect the properties of the resulting raw material:

• Chromium, like nickel, is responsible for imparting rust resistance. With its help, the well-known stainless steel is obtained; the metal is made harder and stronger.
• Nickel adds not only strength, but also ductility.
• Copper, in addition to corrosion resistance, helps resist various acids.
• Vanadium compacts the structure and makes it fine-grained.
• Manganese is responsible for wear resistance.
• Tungsten maintains the hardness of the material when exposed to high temperatures.
• Silicon gives the metal its elasticity and also makes it magnetic.
• The presence of aluminum adds heat resistance to the resulting material.

How does the structure change when various impurities are added? As a result of their introduction, the crystal lattice is destroyed due to differences in the shape of electrons and atomic quantities. Therefore, the characteristics of alloy steel may fluctuate due to changes in the percentage of elements in its composition. The alloy gains hardness, strength and ductility after heat treatment.

Appearance of alloy steel

This metal usually differs in chemical composition. Therefore the classification will be as follows:

1. Low alloyed – the percentage of alloyed additives is no more than 2.5.
2. Medium alloyed - impurities are no more than 2.5-10%.
3. Highly alloyed - impurities can be more than 10% and increase to 50.

According to the classification, it is divided into: corrosion-resistant steel and heat-resistant steel (withstands above 1000 degrees).

According to chemical decomposition, the following are distinguished:

• scale-resistant (at 550 degrees);
• heat resistant.

There are two main types: alloy and carbon. Let's see what differences they have.

Carbon steel is an alloy containing, together with iron and carbon, silicon and manganese. Sulfur and phosphorus, also present in its composition, are considered negative additives, because because of them, its mechanical properties deteriorate.

Steel comes in low, medium and high carbon grades. The greater the proportion of carbon in such alloys, the less their ductility, but the harder the final material is.

Carbon steel is an alloy of iron with carbon up to 2%. Silicon, sulfur and phosphorus are also added to it. However, the main component is still carbon. The percentage of these elements is approximately the following: iron up to 99.0%, manganese - 03-0.8, sulfur up to 0.06 and silicon up to 0.15-0.35.

The main disadvantages of carbon steel:

• if it has good strength and hardness, then it lacks ductility;
• hardness and cutting ability are lost when heated to 200 degrees, and at higher temperatures strength is also lost;
• low resistance to rust when immersed in electrolyte, in aggressive environments, etc.;
• increased coefficient of thermal expansion;
• weighting of finished products;
• increase in the cost of the final product;
• difficulties in design due to the low strength of such steel.

Alloyed – steel, which, along with conventional additives, contains alloyed elements that significantly improve its quality. These are tungsten, molybdenum, nickel, etc. And also manganese and silicon in significant quantities. Impurities are added during melting. This metal is distinguished by its valuable qualities, which are absent in carbon steel, and is free from its disadvantages.

Composition and application of alloy steel

[Alloy steel] is a material whose physical and chemical properties are improved by the addition of alloying elements to the composition.

It is durable, less susceptible to corrosion, and is used in various fields, including mechanical engineering, as well as to create various structures, pipes for various purposes, and parts that will subsequently be subject to high temperature fluctuations.

Types of metal

There are carbon and alloy steels. Let's consider the difference.

Carbon steel is an alloy containing, in addition to iron and carbon, silicon and manganese. Sulfur and phosphorus, also included in the composition, are considered harmful impurities that reduce mechanical properties.

Based on the amount of carbon, such steel is divided into high-, medium- and low-carbon. The more carbon the composition is equipped with, the harder and less ductile the final product will be.

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Carbon steel, in turn, is divided into structural and instrumental types. Structural steel finds its application in the creation of metal structures, pipes, reinforcement for reinforced concrete and other building materials.

Instrumental types - after hardening they become harder, but brittle, their processing requires caution (GOST 1435-54).

Steel also comes in structural, instrumental types, and another type with special chemical properties is added (according to GOST).

Structural alloy steel is also used in mechanical engineering and construction, but it contains alloying impurities that improve the properties of the material from which structures, pipes and other building materials will be made.

The chemical composition of the alloyed metal may vary, based on this, the classification is presented below:

1. Low alloyed – the composition of alloyed additives does not exceed 2.5%. Structural steel is presented in GOST 5958-57 (depending on composition);
2. Medium alloyed - additives included in the composition are in the range of 2.5-10%;
3. Highly alloyed - the percentage of impurities included in the composition exceeds 10% (up to 50%).

The classification is also divided into heat-resistant (more than 1000 degrees), corrosion-resistant, and according to chemical decomposition into heat-resistant and scale-resistant (at 550 degrees).

It should be noted that the GOST classification applies to properties, as well as to the scope of application.

Metal marking

What does the marking of alloy steels mean? Marking according to GOST says the following: the letter means the name of the chemical element, and the number that is located after it indicates the percentage content of this impurity.

If there is no number behind the letter, then the percentage of content of this element is small and does not exceed 1%.

How much carbon is contained in steel can be understood by the first two numbers; it is also indicated as a percentage, but in hundredths. If instead of two there is one digit, it means that the percentage is indicated not in hundredths, but in tenths.

Classification and designation of brands by chemical composition:

Back in the USSR, GOST was developed, according to which this marking system was adopted. The remarkable thing is that it still remains relevant.

It should be noted that the classification and designation of chemical elements by letters does not always correspond to the initial letter of their name: manganese (g), chromium (x), nickel (n), copper (d), vanadium (f), tungsten (v), aluminum ( u), nitrogen (a), etc.

If there is a letter “A” in the middle of the marking, indicating nitrogen, then it indicates the nitrogen content.

If the letter “A” is at the end, then, therefore, sulfur and phosphorus are contained in small quantities (less than 0.03%), such steel is considered pure.

The double letter “A” at the end indicates a particularly pure material containing the above elements. The amount of sulfur is also determined in accordance with GOST.

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Also at the beginning of the marking you can find an additional designation: high-speed steel is designated by the letter “P”, ball-bearing steel is designated by “W”, automatic steel is designated by “A”, electrical steel is designated by the letter “E”, the letter “L” indicates that the steel was produced by casting.

For example, steel marking: 18ХГТ – carbon content is 0.18%, contains chromium, manganese and titanium.

Application of metal

As mentioned earlier, alloy steel has a number of properties that ensure its wide application. It allows the product to increase its service life, ensure its reliability and even save money in some way.

The use of alloy steels can be found in various fields, not only in mechanical engineering and construction, but also in surgery (equipment), the production of pipes for various purposes, and even knives are made from it, which remain sharp for a long time.

The scope of application directly depends on the composition of the elements, what kind of heat treatment was applied, etc. Previously, the classification by purpose (according to GOST) was considered: structural, instrumental and with special properties.

Machine parts, as well as various structures, are often made from pearlitic steels.

Low-alloy materials are characterized by good weldability, therefore they are used to create structures, and pipes are also made from them.

Alloyed tool steels are used to create parts designed to work under pressure (for example, Kh12MF). In the manufacture of cutters, drills and milling cutters, tool steels are also used.

According to GOST 5950-2000, the alloyed material has found its application in the creation of scalpels and knives, band saws, stamps, dies, gear rollers, etc. This GOST specifies the designation of steel and its scope of application.

Stainless steel, which contains chromium (in large quantities), is used in the creation of pipes and pipelines.

Such pipes are resistant to rust and resistant to temperature changes.

Welding alloy steels

Welding of alloy steels and their processing must be carried out taking into account certain points, for example, some elements begin to burn out, the metal at the welding sites begins to self-harden, carbides are released, and cracks may also appear due to the low level of thermal conductivity.

By the way, the thermal conductivity of carbon steel is higher than that of alloy steel.

The welding process must proceed correctly, excluding the phenomena described above.

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To do this, the temperature regime must be observed, thus eliminating the possibility of overheating of the structure; fluxes of various compositions should also be used.

The quality of welding primarily depends on the carbon content: the lower this indicator, the better the quality of welding.

Chromium stainless steel has its own characteristics when welding: due to the low carbon content, the welding process proceeds well.

To prevent stainless chrome steel from fading, use protection for the surface of the future product, as well as electrodes that contain chromium.

To restore viscosity, it is advisable to heat the metal before the process itself (up to 300 degrees), and after welding, anneal the seam (up to 800 degrees). In this case, it is better to use an electric arc.

An important point is that heat treatment of alloy steel with chromium must be carried out at high temperatures. The temperature directly depends on the amount of this element: the more there is, the higher the heat treatment temperature should be.

Stainless chromium-nickel steel at high heat treatment temperatures loses chromium carbides, because of this, the steel’s ability to resist corrosion in the seams is reduced, which is not suitable for the operation of many metal structures and various types of pipes.

To ensure the preservation of stainless properties, niobium or titanium is introduced. Annealing, processing and hardening (cooling) of the weld will ensure resistance to rust.

Manganese metal seams may crack during the welding process. To avoid this, welding is carried out with electrodes whose composition does not differ from the composition of the metal being welded.

Welding and processing must be done quickly, and the seams must be cooled upon completion.

In order for the welding quality to be “at the level”, it is necessary to pre-clean the surface. All scale, slag, and grease must be removed.

It is necessary to clean not only the surface of the intended seam, but also the area next to it (about 10 cm).

Welding or otherwise - heat treatment of alloy steel must occur without interruption and very quickly.

If the material is prone to cracking, then welding (heat treatment) should be carried out indoors, the temperature limit is minus 40 degrees.

The current strength must be constant; condensation, frost, or snow should not form on the surface of the material. It is better to entrust this process to specialists.

Source: https://rezhemmetall.ru/legirovannaya-stal.html

How to decipher steel grade

Alloyed (stainless) steels , unlike unalloyed ones, have a slightly different designation, since they contain elements that are specially introduced in certain quantities to ensure the required physical or mechanical properties. Eg:

• chromium (Cr) increases hardness and strength
• Nickel (Ni) provides corrosion resistance and increases hardenability
• Cobalt (Co) improves heat resistance and increases impact resistance
• Niobium (Nb) helps improve acid resistance and reduces corrosion in welded structures.

That is why it is customary to include in the names of alloy steels the chemical elements present in the composition and their percentage content. Chemical elements in such steel grades are designated by Russian letters given in the table.

X-chrome	A-nitrogen
C-silicon	N-nickel
D-copper	M-molybdenum
T-titanium	K-cobalt
B-tungsten	B-niobium
G-manganese	E-selenium
F-vanadium	C-zirconium
R-boron	U-aluminum

There is also a marking H, which tells us that the alloy contains rare earth metals, such as cerium, lanthanum, neodymium and others. Cerium (Ce) affects the strength and ductility of steel, and neodymium (Nd) and lanthanum (La) reduce porosity and sulfur content in steel and refine the grain.

An example of decoding stainless steel 12Х18Н10Т

12Х18Н10Т is a popular austenitic stainless steel, which is used in welding machines operating in dilute acid solutions, in solutions of alkalis and salts, as well as in parts operating under high pressure and in a wide temperature range. So, what do these mysterious symbols in the name mean, and how to combine them correctly?

The two numbers at the very beginning of the alloy steel grade are the average carbon content in hundredths of a percent. In our case, the carbon content is 0.12%. Sometimes, instead of two numbers, there is only one: it shows how much carbon (C) is contained in tenths of a percent. If there are no numbers at the beginning of the steel grade, this means that there is a fairly decent amount of carbon in it - from 1% and above.

The letter X and the number 18 following it indicate that this brand contains 18% chromium. Please note: the ratio of an element in fractions of a percent expresses only the first number at the beginning of the mark, and this only applies to carbon! All other numbers present in the name express the number of specific elements as a percentage.

Combination H10 follows. As you may have guessed, this is 10% nickel.

At the very end there is the letter T without any numbers. This means that the content of the element is too small to pay attention to. As a rule, about 1% (sometimes up to 1.5%). It turns out that in this grade of alloy steel the amount of titanium does not exceed 1.5%.

If suddenly at the very end of the brand you find a modestly standing letter A, remember that it plays a very important role: this means high-quality steel, the content of phosphorus and sulfur in which is kept to a minimum.

Two letters A at the very end (AA) indicate that this grade of steel is especially pure, i.e. there is practically no sulfur and phosphorus here.

In the course of a simple analysis of combinations of letters and numbers, we found out that the steel grade 12Х18Н10Т (structural cryogenic, austenitic class) reports the following information about itself: 0.12% carbon, 18% chromium (X), 10% nickel (N) and a small content titanium (T), not exceeding 1.5%.

At the beginning of the alloy steel grade there may also be additional designations:

R - high-speed;

Ш - ball bearing;

A - automatic (do not confuse with the letter A at the end of the name, which indicates the purity of the steel!);

E - electrical.

It is also worth noting some features of these subtypes of alloy steels:

1. in ball bearing steels, the chromium content is indicated in tenths of a percent (for example, ShKh4 steel contains 0.4% chromium);

2. In high-speed steel grades, after the letter P there is immediately a number indicating the tungsten content as a percentage. Also, all high-speed steels contain 4% chromium (X).

To show the method of steel deoxidation, there are special letter designations:

• sp - mild steel;
• ps - semi-quiet steel;
• kp - boiling steel.

Now let’s take a closer look at how to decipher the grade of non-alloy steel, which is divided into ordinary and high-quality.

Ordinary unalloyed steel (St3, St3kp) has the letters St at the very beginning. This is followed by a number indicating the conditional number (grade) of steel: from 0 to 7. The higher the number, the higher the carbon content C.

At the end there may be special indices: for example, St3kp steel belongs to the boiling category, as indicated by the letters kp at the very end. The absence of an index means that this steel is calm. When it is necessary to reflect the guarantee of weldability in the marking, the lowercase letters St. are added at the end. For example: St3st.

High-quality unalloyed steel (St10, St30, St20, St45) contains a two-digit number in the marking, indicating the average carbon content in the steel in hundredths of a percent. Thus, steel grade St10 contains 0.1% carbon; St30 has 0.3% carbon; St20 - 0.2%; St45 contains 0.45% carbon.

Structural low-alloy steel 09G2S contains the following chemical elements: 0.09% carbon, 2% manganese and a small amount of silicon (approximately 1%).

Steels 10KhSND and 15KhSND differ only in different carbon content: 0.1% and 0.15%, respectively. There is very little chromium (X), silicon (C), nickel (H) and copper (D) here (up to 1-1.5%), so numbers are not placed after the letter.

High-quality steels are used for the production of steam boilers and high-pressure vessels. Their markings have the letter K at the end: 20K, 30K, 22K.

If the steel is structural casting, then the letter L is placed at the end of the marking. For example: 40ХЛ, 35ХЛ.

Non-alloy tool steels are designated by the letter U. This is followed by a number expressing the average carbon content in the steel: U10, U7, U8. If the steel is also high-quality, this is also noted in the marking: U8A, U10A, U12A. If it is necessary to emphasize the increased manganese content, an additional letter G is used. For example, there are U8GA and U10GA steels.

Tool alloy steels have the same designation as structural alloy steels. For example, the HVG brand indicates the presence of three main alloying elements: chromium (X), tungsten (B) and manganese (G). There is approximately 1% carbon here, and therefore the number is not written at the beginning of the stamp. Another type of steel, 9KhVG, has a lower carbon content compared to KhVG: here there is 0.9% carbon.

High-speed steels are marked with the letter P, followed by the tungsten content in %. Let's take steel R6M5F3 as an example. It is high-speed (P), contains 6% tungsten, 5% molybdenum (M) and 3% vanadium (F).

Unalloyed electrical steel (ARMCO) has a very low electrical resistivity. This is achieved due to the minimal amount of carbon in the composition (less than 0.04%). Such steel is also commonly called technically pure iron. The marking of electrical non-alloy steels consists only of numbers. For example: 10880, 21880, etc.

Each number contains important information. The very first digit shows the type of processing: 1 - forged or hot-rolled; 2 - calibrated. The second digit indicates the presence/absence of a normalized aging coefficient: 0 - without a coefficient; 1 - with a coefficient. The third digit is the group according to the main standardized characteristic.

The last two are associated with the values ​​of the main standardized characteristic.

Structural steel is marked with the letter C, followed by the minimum yield strength of the steel. Additional designations are also used: K - increased corrosion resistance (S390K, S375K); T - heat-strengthened rolled products (S345T, S390T); D - increased copper content (S345D, S375D).

Aluminum casting alloys are designated by the letters AL at the beginning of the marking. Here are some examples: AL4, AL19, AL27.

Aluminum alloys for forging and stamping contain the letters AK, and then the conditional number of this alloy: AK6, AK5.

There are also wrought alloys containing aluminum. Avial alloy: AB, aluminum-magnesium alloy: AMg; aluminum-manganese alloy: AMts.

Now you have learned how to decipher the grade of steel containing various chemical elements. This steel marking was developed back in the USSR and is still in effect not only in the Russian Federation, but also in the CIS countries.

European steel markings are subject to the EN 100 27 standard. Japan and the United States have their own standards. There is currently no single world classification of steels.

Understanding the general rules for designating grades of unalloyed and alloyed steels, as well as by correctly deciphering steel grades, you can easily determine what kind of steel a particular part is made of. 

Source: https://kst21.ru/info/stati/kak-rasshifrovat-marku-stali/

Steel marking: what it depends on and how it is marked, a table with a breakdown of metals and alloys

December 25, 2019 7 minutes to read524

Any craftsman who works with metal products knows what a “steel grade” is. Deciphering it allows you to get an idea of ​​the chemical composition and physical parameters, which is fundamental information for creating any objects made of metal.

Many people believe that marking steel and rolled metal products is a complex process that requires special knowledge. However, despite the apparent complexity, it is quite simple to understand.

To do this, you only need to know the principle of its compilation and how it is classified, which this article will tell you about.

The alloy is marked with letters and numbers, making it possible to determine the presence of chemical elements and their volume as accurately as possible. Based on this data, as well as knowledge of how different chemicals interact with the metal base, it is possible to understand with maximum accuracy what technical properties relate to a particular steel grade.

Types of steels and features of marking

Steel is an iron-carbon alloy, the amount of which does not exceed 2.14%. The carbon component is necessary to achieve hardness, but it is extremely important to monitor its concentration. If it exceeds 2.2%, the metal will become very brittle, making it almost impossible to work with.

By adding any alloying elements, the required characteristics can be achieved. It is by combining the type and volume of additives that grades are obtained that have better mechanical properties and resistance to corrosion. Of course, quality indicators can be improved through heat treatment, but the use of alloying additives significantly speeds up this process.

The basic classification criteria are the following indicators.

• Chemical composition.
• Purpose.
• Quality.
• Structure.
• Degree of deoxidation.

What does the marking show?

In order to decipher the specified information, you do not need to have professional skills or special knowledge. Structural steel, which is of normal quality and also does not contain alloying elements, received the “St” mark.

The number below reflects the amount of carbon. After them there may be the letters “KP”, which indicate unfinished deoxidation in the furnace, therefore such an alloy is considered boiling.

If there is no such abbreviation, then he is considered a calm type.

Marking and classification of steel by chemical composition

As mentioned earlier, one of the main divisions of this metallic material is based on its chemical composition. The basic components of the material are reinforced concrete and carbon (its concentration is less than 2.14%). Based on the concentration and proportions of additives used, iron accounts for at least half the volume.

Based on the level of carbon content, steel products are divided.

1. Low-carbon - carbon no more than 0.25%.
2. Medium carbon - from 0.25 to 0.6%.
3. High carbon - from 0.6%.

Increasing the carbon component helps to increase metal hardness, but at the same time reduces its strength. To improve the performance of alloys, various chemical elements are added to them, after which they are converted into alloy steels. They come in three types.

1. Low alloyed - the volume of additives is less than 2.5%.
2. Medium alloyed - 2.5-10%.
3. Highly alloyed - can reach 50%.

steel grade

WITH%

Source: https://www.cleverence.ru/articles/auto-busines/markirovka-stali-ot-chego-zavisit-i-kak-markiruetsya-tablitsa-s-rasshifrovkoy-metallov-i-splavov/

Alloy steel - types, characteristics, alloy scrap

Everyone knows the difference between steel structures and their cast iron counterparts. In fact, the two types of ferrous metal differ in the concentration of carbon relative to iron. The limiting value of carbon concentration is 2.14% and was not chosen by chance.

This is the threshold value of the solubility of element C in austenite, a high-temperature modification of Fe with a face-centered lattice. Modern technologies make it possible to overcome the limit: the carbon content in high-carbon steels is up to 3.4%.

However, the essence of the epilogue is different: steel is iron alloyed with carbon, and the addition of other metals allows you to control the properties of the ferrous metal.

The process is similar to a child playing with a construction set, when, often, only practical experiment allows one to determine the effectiveness of alloying. Indeed, the influence of alloying elements on the properties of steel often remains at an empirical level and does not follow a certain logic.

The only exception is, perhaps, Vanadium, an element whose addition to steel improves characteristics such as ductility and hardness.

Alloy steels classification and marking

Basic sorting of low-carbon iron allows it to be divided into two varieties. In fact, the main classification of alloy steels is based on the method of their use:

1. Structural . Steel used in the manufacture of parts, assemblies and structures.
2. Instrumental . The metal is characterized by a carbon content of 0.9 – 1.4%. Additional alloying elements in tool steels: chromium, vanadium, tungsten, silicon, manganese and others. The total concentration of impurities, excluding carbon, does not exceed 5%. Used in the production of impact and cutting tools.

Classification of alloy steels by purpose

The first general question is what does alloy steel mean? Already received the answer above. This is a type of low-carbon iron that has other metals incorporated to improve certain parameters. This term also provides an answer to the following question: why are alloying elements introduced into steel? Thus, having understood what alloyed and unalloyed steel is, we can move on to consider the two basic varieties of this metal.

Marking of alloy steels

Structural alloy steels

Thick-walled structural steel pipes

The classification of this type of low-carbon iron is quite extensive. Among the parameters that determine the sorting of structural steel are:

• percentage mass of alloying elements;

• chemical composition and base admixture;

• quality of the metal, its surface (two different categories);

Source: http://xlom.ru/spravochnik/legirovannyj-stali-vidy-xarakteristika-legirovannyj-metallolom/

Classification and marking of alloy steels

Purpose of the work : familiarize yourself with the classification and marking of alloy steels.

General instructions

Alloyed steels are steels that contain, in addition to iron and carbon, specially introduced elements that can change its structure, and therefore its properties.

In accordance with the generally accepted classification, all chemical elements contained in rose can be divided into four groups:

1. Permanent or ordinary impurities. This group includes manganese, silicon, aluminum, titanium, which enter the steel during deoxidation and are present in the steel in small quantities. Permanent impurities include sulfur and phosphorus.

2. Hidden impurities. These are oxygen, hydrogen and nitrogen, present in all steel in very small quantities.

3. Random impurities. This group includes impurities that enter steel from charge materials or due to any accidental reasons (for example, when remelting scrap metal - tinned, galvanized).

4. Alloying elements. These are elements that are specially introduced into a plant in certain quantities in order to change its structure and properties.

For steel alloying, chromium, nickel, manganese, silicon, tungsten, vanadium, molybdenum, titanium, copper, etc. are most often used.

Classification of alloy steels

Classification by purpose. Depending on the purpose, steel can be combined into the following groups.

I. Structural steel used for the manufacture of machine parts, structures and structures.

II. Tool steel used for the production of cutting, measuring, stamping and other tools.

III. Steels and alloys with special physical and chemical properties. These include steels that have some clearly defined properties: stainless, heat-resistant, heat-resistant, wear-resistant, with features of thermal expansion, special magnetic and electrical properties, etc.

Classification by chemical composition. Depending on the composition, alloy steels are classified as nickel, chromium, chromium-nickel, chromium-nickel-molybdenum and the like. The classification feature is the presence of certain alloying elements in the steel.

Letter	Element	Letter	Element	Letter	Element
A	nitrogen	TO	cobalt	T	titanium
B	niobium	N	nickel	F	vanadium
IN	tungsten	M	molybdenum	X	chromium
G	manganese	P	phosphorus	C	zirconium
D	copper	R	boron	H	rare earth
E	selenium	WITH	silicon	YU	aluminum

The chemical composition of alloy steel is the basis for establishing its grade according to GOST.

Alloy steels are marked with numbers and letters. Alloying elements are designated by letters:

Each grade of steel is made up of a combination of letters and numbers. In structural steels, the first two numbers indicate the average carbon content in hundredths of a percent. In tool steels, the first digit indicates the average carbon content in tenths of a percent, if its content is 1%. If the carbon content of tool steels is more than 1%, then the figure is often missing.

The letters indicate alloying elements, and the following numbers indicate the average content (in whole percent) of the corresponding alloying element; the absence of a number indicates that it is 1 1.5% or less. The exception is expensive and highly scarce carbide-forming elements: Mo, W, V, Ti.

These elements are added in small quantities (for example, up to 0.3% Vi and 0.1% Ti), therefore, in the brand decoding it is necessary to indicate that the content of these elements is up to 1%.

Carbon content classification:

a) low-carbon (0.025 0.25% C);

b) medium-carbon (0.25 0.6% C);

c) high-carbon (0.6% C).

Classification according to the content of alloying elements:

1. Low alloy steel – alloying elements up to 2.5%.

2. Alloy steel – alloying elements 2.5 ÷ 10%.

3. High-alloy steel – alloying elements more than 10% (with Fe content > 45%).

Classification by quality. The quality of steel is determined by the content of harmful impurities in them: sulfur and phosphorus. Based on quality, alloy steels are divided into three groups.

The bulk of alloyed steels are smelted of high quality (0.035% P and 0.035% S).

High-quality steels contain fewer harmful impurities (0.025% P and 0.025% S) and are designated by the letter A placed at the end of the brand.

Particularly high-quality steels contain a minimum amount of harmful impurities (up to 0.015% S, up to 0.025% P). Such steels are designated by the letter Ш, placed through a hyphen at the end of the mark.

Classification by structure. The classification of steels is most often considered according to the structure obtained after cooling in air at 900 0C. In accordance with this classification, alloy steels are divided into five classes: ferritic, pearlitic, martensitic, austenitic and carbide (ledeburite).

Source: https://studfile.net/preview/5056482/page:4/

Structural alloy steels markings and applications - Metals, equipment, instructions

Alloy structural steel is indispensable for production in construction and mechanical engineering. This is due to the fact that it has certain mechanical, physical and chemical properties. A certain property is specified by the content of a particular element, due to the content of which it will be endowed with a certain quality.

Steel composition

Alloy steel uses the following elements in its composition:

Manganese (Mn) - G; silicon (Si) - C; chromium (Cr) - X; nickel (Ni) - H; copper (Cu) - D; nitrogen (N) - A; vanadium (V) - F; niobium (Nb) - B; tungsten (W) - B; selenium (Se) - E; cobalt (Co) - K; beryllium (Be) - L; molybdenum (Mo) - M; boron (B) - P; titanium (Ti) - T; aluminum (Al) - Yu.

In addition to the basic elements included, the following have been added:

• Chroma.
• Nickel.
• Cobalt.
• Aluminum.
• Vanadia

The main one of the most important parameters by which steel is divided into various classes is their chemical composition of elements.

The remaining additions give the metal its distinctive qualities. The added chromium gives the alloy an increased level of strength and fluidity, despite this, maintaining an acceptable level of toughness. The addition of tungsten provides the alloy with normal hardness and sets a good level of stability during tempering. The addition of molybdenum sets the level of hardenability and increases the level of ductility and viscosity.

Composition differences vary based on the total percentage of alloying elements:

• For highly alloyed ones – more than 10%.
• For medium alloyed ones – more than 2.5 – 10%.
• For low-alloyed ones – no more than 2.5%.

Structural alloy steels have a certain advantage after heat treatment, in contrast to carbon steels. This suggests that alloying elements significantly influence the diffusion processes that occur during heat treatment. A larger number of alloying elements have been added to the material, which is why they come in the guise of rolled products, these are round, square, hexagonal, and sometimes as calibration sheets, forgings and other semi-finished products.

How is structural alloy steel marked?

Grades of structural alloy steels consist of letters and numbers. Letters are alloying elements, each of which is included in the composition. The number indicates the quantitative presence of carbon and alloying element.

They are marked this way. A two-digit number is placed at the beginning, which expresses the approximate average level of carbon contained, which is indicated in hundredths of a percent. Letters indicate alloying elements. The current markings are: X-Cr, N - Ni, M-Mo, G - Mn, D - Cu, B-W, F-V, B - Nb, P - B, K-Co, C-Si, T - Ti, C - Zr, Yu - A1, P - P, A-N. The numbers after the letter indicate the average occurrence of the specified element as a percentage.

In the case where the contained element has a content of less than 1%, the number is not given. If there is an “A” at the end, it means the steel is of high quality. This means that the amount of sulfur and phosphorus contained is no more than 0.02%.

Where is structural alloy steel used?

Since the scope of application of structural steel is very wide, it is important to know the area of ​​​​use of the material, and what grade is used for what.

• 60С2(A) – for springs, for the production of which strip steel with a thickness of 3 to 16 mm is used. Spring bands, thickness from 0.08 to 3 mm. Twisted springs made of 16 mm wire.
• 70SZA – for heavily loaded springs with critical purposes. Steel prone to graphitization.
• 50ХГ(А) – for springs, the production of which requires strip steel from 3 to 18 mm in thickness.
• 50HFA (HGFA) - for critical springs and springs that operate at elevated temperatures, which do not exceed 300 degrees, or for those subjected to frequent variable loads.
• 60C2XA – for large, highly loaded springs and springs with critical applications.
• 60C2H2A(C2BA) – for critical, highly loaded springs and springs, which are made of spring bands and calibrated steels.
• 20X – for claw couplings, bushings, spindles, guide bars, plungers, mandrels, copiers, spline rollers, etc.
• 40X – for gears, spindles and shafts in rolling bearings, worm shafts.
• 45X, 50X - for gears, spindles, shafts in rolling bearings, worm and spline shafts, as well as other parts that operate at medium speed and medium pressure.
• 38ХА - for gears that operate at medium speed and medium pressure.
• 45G2, 50G2 - for large lightly loaded parts, including shafts, gears on heavy machines, etc.
• 18ХГТ - for parts that operate at high speed under high pressure and load.
• 20ХГР – for heavily loaded parts that operate at high speed and load.
• 15ХФ - for small parts that are subjected to carburization and hardening with low tempering.
• 40ХС – for small parts that have a high level of strength.
• 40HFA - for critical and high-strength parts that are subject to hardening and high tempering. For small and medium-sized parts with complex shapes that are subject to wear. Also critical welded structures that operate under alternating load conditions.
• 35ХМ – for shafts, turbine parts and fasteners that operate at elevated temperatures.

Read also: How to produce steel from cast iron in modern production

Since each type of steel has its own specific advantages, it is important to understand which will be most suitable for what. As the main parts that experience severe loads and have a high level of wear, alloyed structural steels of their grade and application are indispensable.

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Source: https://spb-metalloobrabotka.com/konstruktsionnye-legirovannye-stali-markirovka-i-primeneniya/

Alloy steel

Kashtanovy lane 8/14 51100 Magdalinovka village

Nikolaenko Dmitrij

Alloy steel Alloy steel ( 1 vote, average: 4 out of 5)

Alloy steel is steel that includes various alloying elements that give the steel the desired mechanical and physical properties.

These elements also significantly increase corrosion resistance, resistance to brittleness and increase strength.

Elements of alloy steel can be included in the following list:

• nitrogen;
• copper;
• nickel;
• chromium;
• vanadium.

These are classic additives that are used as much as possible in production. Alloy steel is divided into three main classes:

• low alloy;
• highly alloyed;
• medium alloyed.

The classification of alloyed steels is based on the percentage of alloyed elements. Each of these types of steel is produced by metallurgical means, however, in some cases, alloying can be done only on a certain surface in order to impart the necessary strength properties to products and parts.

Alloy steel acquires its properties at various stages of metal production, as alloying elements are added. Alloy steel may include one to several alloying elements that increase the structural strength of the alloy.

Alloy steel is produced in several main types:

• instrumental;
• structural;
• steel having special chemical and physical properties.

Marking of alloy steels

Marking of alloyed steels is carried out using letters that indicate which alloying element is contained in the alloy, and numbers that determine the average content of this element as a percentage. The numbers at the beginning of the brand name indicate how much carbon the material contains. If two digits are specified, hundredths of a percent are included, if one digit is specified, tenths. Marking of alloy steels may have additional designations. For example, there are common notations:

• R - high-speed;
• Ш – ball bearing;
• A - automatic;
• L - obtained by casting;
• E - electrical.

The nitrogen content is indicated by the letter A located in the middle of the mark. Two letters A (AA) indicate the composition of extra pure steel and these letters appear at the end. Especially high-quality steel has the letter Ш at the end of the mark. Examples of marking alloy steels:

18HGT means:

• 0.18% C;
• 1% Cr;
• 1% Mn;
• 0.1% Ti.

Steel 30KhGSA contains:

• 0.30% C;
• 0.8-1.1% Cr;
• 0.9-1.2% Mn;
• 0.8-1.25% Si.

Purpose of alloy steels

The purpose of alloyed steels is very diverse, since, having the appropriate alloying additives in its composition, such steel is able to withstand various types of loads, unlike conventional steel. Most indicators can be adjusted by adding the desired alloying elements.

The main purpose of alloy steels is the manufacture of surgical instruments, jewelry equipment, various metal structures, construction fittings, industrial machines, and mechanisms that experience heavy loads during operation. Tool grades of alloy steels are used for the manufacture of parts that operate under high pressure; they are also used in the manufacture of standard gears, rollers of complex shapes, sections of forging dies, etc.

etc. Other grades are used for parts with increased wear resistance, good bending strength, contact load, and the required excellent elasticity.

Types of Alloy Steel

Types of alloy steel are distinguished according to the percentage of alloying elements in the alloy. This is how they are classified:

• low-alloy and contain up to 2.5% alloying elements;
• medium alloyed, having from 2.5 to 10% alloyed elements;
• highly alloyed ones have 10 - 50% of such elements.

types of alloy steel . They are classified depending on the percentage of highly effective components, for example: zirconium, vanadium, tantalum, other chemical elements, such as carbon, as well as structural specifics:

• ledeburite – the presence of primary carbides;
• eutectoid – pearlitic metal structure;
• hypereutectoid – the presence of secondary carbides;
• hypoeutectoid - there is excess ferrite.

Depending on the degree of use and purpose, steels can be classified into: structural, instrumental, and with special properties.

Types of alloy steel also include stainless steel, which have excellent properties of resistance to chemical and electrochemical corrosion.

Special heat-resistant, having good resistance to chemical destruction in a gas environment at temperatures above 500 C, but at the same time they operate in a lightly loaded state or not loaded.

Heat-resistant steels that work under heavy loads for a sufficient time and at the same time maintain sufficient heat resistance. Types of alloy structural steel are:

• quality;
• high quality;
• very high quality.

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Source: https://metallsmaster.ru/legirovannaya-stal/

Types and interpretation of alloy steel markings

To improve technical characteristics, alloying substances are added to the metal. In addition to improving physical properties, appearance may change. Due to the many alloying components, it is impossible to understand the material without symbols. For this purpose, marking of alloy steels is used.

• Description of metal
• Why label?
• Designation
• Examples
• Decoding

Description of metal

Alloy steel is an alloy of iron and carbon that contains impurities. Depending on the additives and time of manufacture, the material can acquire different properties:

• resistance to rust formation;
• high strength index;
• elasticity, refractoriness.

The most popular additives are copper, chromium, tungsten, molybdenum, and nickel.

Depending on the amount of additives, alloys are divided into three groups:

• low-alloyed - the amount of impurities does not exceed 2.5%;
• medium alloyed - additives contain from 2.5 to 10%;
• highly alloyed - impurities more than 10%.

The composition of medium-alloy steels is often diluted with particles of molybdenum, tungsten, vanadium, and nickel. Thanks to this, optimal indicators of plasticity, viscosity, and strength are achieved. The main additional components of high-alloy alloys are nickel and chromium. The material becomes corrosion resistant and heat resistant.

Why label?

Alloys are marked according to GOST. The brand indicates their purpose, basis, and the presence of impurities. For example, they can be instrumental (used to make working parts of various tools), structural (used to create metal structures, car bodies). Additional letters may denote materials that have special physical properties (magnetic, heat-resistant, corrosion-resistant).

The quality of the alloy is determined by the percentage of additives in the composition. For example, the content of phosphorus and sulfur should be minimal. The components are indicated by capitalizing the element letters.

Source: https://metalloy.ru/stal/markirovka-legirovannoy-stali