Where are alloyed structural steels used?

The influence of alloying elements on the properties of steel. Types, grades and purpose of steels

Steel is one of the most sought after materials in the world today. Without it, it is difficult to imagine any existing construction site, engineering enterprises, and many other places and things that surround us in everyday life. At the same time, this alloy of iron and carbon can be quite different, therefore this article will consider the influence of alloying elements on the properties of steel, as well as its types, grades and purpose.

general information

Today, many steel grades are widely used in almost every area of ​​human activity. This is largely due to the fact that this alloy optimally combines a whole range of mechanical, physico-chemical and technological properties that no other materials have. The steel smelting process is continuously being improved and therefore its properties and quality make it possible to obtain the required performance indicators of the resulting mechanisms, parts and machines.

Classification by purpose

Each steel, depending on what it is created for, can necessarily be classified into one of the following categories:

• Structural.
• Instrumental.
• Special purpose with special properties.

The most numerous class is structural steels, designed to create a variety of building structures, instruments, and machines. Structural grades are divided into upgradeable, cemented, spring-spring, and high-strength.

Tool steels are differentiated depending on the tool for which they are produced: cutting, measuring, etc. It goes without saying that the influence of alloying elements on the properties of steel in this group is also great.

Special steels have their own division, which includes the following groups:

• Stainless (aka corrosion-resistant).
• Heat resistant.
• Heat resistant.
• Electrical.

Steel groups by chemical composition

Steels are classified according to the chemical elements that form them:

• Carbon steel grades.
• Alloyed.

Moreover, both of these groups are further divided according to the amount of carbon they contain into:

• Low carbon (carbon less than 0.3%).
• Medium carbon (carbon concentration is 0.3 - 0.7%).
• High carbon (carbon more than 0.7%).

What is alloy steel?

This definition should be understood as steels that contain, in addition to permanent impurities, also additives introduced into the structure of the alloy in order to increase the mechanical properties of the ultimately obtained material.

A few words about steel quality

This parameter of a given alloy implies a set of properties, which, in turn, are determined directly by the process of its production. Similar characteristics that alloy tool steels are subject to include:

• Chemical composition.
• Uniformity of structure.
• Manufacturability.
• Mechanical properties.

The quality of any steel directly depends on how much oxygen, hydrogen, nitrogen, sulfur and phosphorus it contains. The method of producing steel also plays an important role. The most accurate method from the point of view of falling into the required range of impurities is the method of steel smelting in electric furnaces.

Alloy steel and changes in its properties

Alloy steel, the grades of which contain in their markings the letter designations of forcedly introduced elements, changes its properties not only from these third-party substances, but also from their mutual action with each other.

If we consider carbon specifically, then according to their interaction with it, alloying elements can be divided into two large groups:

• Elements that form a chemical compound (carbide) with carbon are molybdenum, chromium, vanadium, tungsten, manganese.
• Elements that do not create carbides are silicon, aluminum, nickel.

It is worth noting that steels that are alloyed with carbide-forming substances have very high hardness and increased wear resistance.

Low alloy steel (grades: 20KhGS2, 09G2, 12G2SMF, 12KhGN2MFBAYU and others). A special place is occupied by the 13X alloy, which is hard enough to make surgical, engraving, jewelry equipment, and razors from it.

Decoding

Alloying elements in steel can be determined by its marking. Each of these components introduced into the alloy has its own letter designation. For example:

• Chromium – Cr.
• Vanadium –V.
• Manganese –Mn.
• Niobium – Nb.
• Tungsten –W.
• Titanium – Ti.

Sometimes there are letters at the beginning of the steel grade index. Each of them carries a special meaning. In particular, the letter “P” means that the steel is high-speed, “W” indicates that the steel is ball-bearing, “A” is automatic, “E” is electrical, etc. High-quality steels have a number and letter designation at the end the letter “A”, and especially high-quality ones contain the letter “Ш” at the very end of the marking.

Impact of alloying elements

First of all, it should be said that carbon has a fundamental influence on the properties of steel. It is this element that, with increasing concentration, provides an increase in strength and hardness while reducing viscosity and plasticity. In addition, increased carbon concentration guarantees deterioration in machinability.

chromium in steel directly affects its corrosion resistance. This chemical element forms a thin protective oxide film on the surface of the alloy in an aggressive oxidizing environment. However, to achieve this effect, the steel must contain at least 11.7% chromium.

Aluminum deserves special attention. It is used in the process of alloying steel to remove oxygen and nitrogen after purging it in order to help reduce the aging of the alloy. In addition, aluminum significantly increases impact strength and fluidity, and neutralizes the extremely harmful effects of phosphorus.

Vanadium is a special alloying element that gives alloyed tool steels high hardness and strength. At the same time, the grain in the alloy decreases and the density increases.

Alloy steel, the grades of which contain tungsten, is endowed with high hardness and red resistance. Tungsten is also good because it completely eliminates brittleness during the planned tempering of the alloy.

To increase heat resistance, magnetic properties and resistance to significant impact loads, steel is alloyed with cobalt. But one of those elements that does not have any significant effect on steel is silicon. However, in those grades of steel that are intended for welded metal structures, the silicon concentration must necessarily be in the range of 0.12-0.25%.

Magnesium significantly increases the mechanical properties of steel. It is also used as a desulfurizer in the case of off-furnace desulfurization of cast iron.

Low-alloy steel (its grades contain alloying elements less than 2.5%) very often contains manganese, which provides it with an inevitable increase in hardness and wear resistance while maintaining optimal ductility. But the concentration of this element must be more than 1%, otherwise it will not be possible to achieve the specified properties.

Carbon steel grades, smelted for various large-scale building structures, contain copper, which provides maximum anti-corrosion properties.

To increase red-hardness, elasticity, tensile strength and corrosion resistance, molybdenum is necessarily introduced into the steel, which also increases the resistance to oxidation of the metal when heated to high temperatures. In turn, cerium and neodymium are used to reduce the porosity of the alloy.

When considering the influence of alloying elements on the properties of steel, one cannot ignore nickel. This metal allows steel to achieve excellent hardenability and strength, increase ductility and impact resistance, and lower the cold brittleness limit.

Niobium is also widely used as an alloying additive. Its concentration, 6-10 times higher than the amount of carbon necessarily present in the alloy, eliminates intergranular corrosion of stainless steel and protects welds from extremely unwanted destruction.

Titanium allows you to obtain the most optimal strength and ductility indicators, as well as improve corrosion resistance. Those steels that contain this additive are very well processed with various special-purpose tools on modern metal-cutting machines.

The introduction of zirconium into a steel alloy makes it possible to obtain the required grain size and, if necessary, influence grain growth.

Random impurities

Extremely undesirable elements that have a very negative impact on the quality of steel are arsenic, tin, and antimony. Their appearance in the alloy always leads to the steel becoming very brittle along its grain boundaries, which is especially noticeable when winding steel strips and during the annealing process of low-carbon steel grades.

Conclusion

Nowadays, the influence of alloying elements on the properties of steel has been quite well studied. Experts carefully analyzed the impact of each additive in the alloy.

The theoretical knowledge obtained allows metallurgists, already at the stage of placing an order, to formulate a schematic diagram of steel smelting, determine the technology and the amount of required consumables (ore, concentrate, pellets, additives, etc.).

Most often, steelmakers use chromium, vanadium, cobalt and other alloying elements, which are quite expensive.

Source: https://FB.ru/article/288755/vliyanie-legiruyuschih-elementov-na-svoystva-stali-vidyi-marki-i-naznachenie-staley

Structural alloy steels: properties, grades, classification - Website about

17.12.2019

• Characteristic
• Properties
• Stamps

In the modern world there are a large number of varieties of steel. This is one of the most popular materials, which is used in almost all industries.

Characteristics of alloy steels

Alloy steel is steel that, in addition to the usual impurities, is also equipped with additional additives that are necessary for it to meet certain chemical and physical requirements.

Ordinary steel consists of iron, carbon and impurities, without which it is impossible to imagine this material. Additional substances are added to alloy steel, which are called alloying substances. They are used to ensure that steel has the properties that are necessary in certain situations.

In most cases, the following are added to iron, impurities and carbon as alloying elements: nickel, niobium, chromium, manganese, silicon, vanadium, tungsten, nitrogen, copper, cobalt. It is also not uncommon for such materials to contain substances such as molybdenum and aluminum. In most cases, titanium is added to add strength to the material.

This type of steel has three main categories. The relationship of alloy steel to a particular group is determined by how much steel and impurities it contains, as well as alloy additives.

Types of Alloy Steel

There are three main types of steel with alloying elements:

It is characterized by the fact that it contains about two and a half percent of alloying additional elements.

• Medium alloy steel.

This material contains from 2.5 to 10 percent of additional alloying substances.

• High alloy steel.

Purpose of alloy steel

Alloy steel is widely used in modern industry. It has a high level of strength, which allows it to be used to manufacture equipment for cutting and chopping rolled metal of various types.

According to their purpose, alloy steels can be represented by a large number of groups.

The main ones are:

• structural alloy steel,
• tool alloy steel,
• alloy steel with special chemical and physical properties.

The characteristics of alloy steels can be varied. They acquire them due to the ratio of the basic elements. Steels of this type are in any case more durable and resistant to corrosion.

Properties of alloy steel

The properties of alloy steels are varied. They are mainly determined by those additives that are used as alloying agents in the production of certain types of steel materials.

Depending on the added alloying components, steel acquires the following qualities:

• Strength. This property is acquired after adding chromium, manganese, titanium, and tungsten to its composition.
• Resistant to corrosion. This quality appears under the influence of chromium and molybdenum.
• Hardness. Steel becomes harder thanks to chromium, manganese and other elements.

Attention: It is worth noting that in order for alloy steel to be more durable and resistant to external environmental influences, the required chromium content should not be less than twelve percent.

Alloy steel, with the correct percentage of all elements included in it, should not change its quality when heated to temperatures up to six hundred degrees Celsius.

Alloy steel grades

Alloy steel grades vary. They are presented in a wide variety. Depending on the purpose of the steel, its marking is determined.

Today there are a large number of requirements for marking alloy steel. Numerical and alphabetic notations are used for this process. First, numbers are used for marking.

They are indicators of how many hundredths of carbon are contained in a particular type of alloy steel.

After the numbers there are letters, which indicate which alloying additives were used in the production of a particular type of alloy steel.

The letters may be followed by numbers indicating the amount of alloying substance in the steel material. If there is no digital designation after the designation of any alloying element, then it contains a minimum amount of it, not reaching even one percent.

Table 1. Comparison of steel grades of type Cm and Fe according to international standards ISO 630-80 and ISO 1052-82

Steel gradesStFeStFe

One hundred	Fe310-0	St4kp	Fe430-A
St1kp	St4ps	Fe430-B
St1ps	St4sp	Fe430-C
St1sp	—	—	Fe430-D
St2kp	St5ps	Fe510-B, Fe490
St2ps	St5Gps	Fe510-B, Fe490
St2sp	Sg5sp	Fe510-C, Fe490
StZkp	Fe360-A
StZps	Fe360-B	St6ps	Fe590
StZGps	Fe360-B	Stbsp	Fe590
StZsp	Fe360-C	Fe690
StZGsp	Fe360-C	—
Fe360-D

Table 2. Symbols of alloying elements in metals and alloys

ElementSymbolDesignation of elements in grades of metals and alloysElementSymbolDesignation of elements in grades of metals and alloysblackcoloredblackcolored

Nitrogen	N	A	—	Neodymium	Nd	—	Nm
Aluminum	A1	YU	A	Nickel	Ni	—	N
Barium	Va	—	Br	Niobium	Nb	B	Np
Beryllium	Be	L	Tin	Sn	—	ABOUT
Bor	IN	R	—	Osmium	Os	—	OS
Vanadia	V	f	To you	Palladium	Pd	—	front
bismuth	Bi	In and	In and	Platinum	Pt	—	Pl
Tungsten	W	IN	—	Praseodymium	Pr	—	Etc
Gadolinium	Gd	—	Gn	Rhenium	Re	—	Re
Gallium	Ga	Gi	Gi	Rhodium	Rh	—	Rg
Hafnia	Hf	—	Gf	Mercury	Hg	—	R
Germanium	Ge	—	G	Ruthenium	Ru	—	Pv
Holmium	But	—	GOM	Samarium	Sm	—	Myself
Dysprosium	Dv	—	DIM	Lead	Pb	—	WITH
Europium	Eu	—	Ev	Selenium	Se	TO	ST
Iron	Fe	—	AND	Silver	Ag	—	Wed
Gold	Au	—	Evil	Scandium	Sc	—	From km
Indium	In	—	In	Antimony	Sb	—	Cv
Iridium	Ir	—	AND	Thallium	Tl	—	Tl
Ytterbium	Yb	—	ITN	Tantalum	Ta	—	TT
Yttrium	Y	—	THEM	Tellurium	Those	—	T
Cadmium	Cd	CD	CD	Terbium	Tb	—	Volume
Cobalt	Co	TO	TO	Titanium	Ti	T	TPD
Silicon	Si	WITH	Kr(K)

Source: https://nzmetallspb.ru/osnastika/legirovannye-stali-konstruktsionnye-svojstva-marki-klassifikatsiya.html

Features of alloy steel - varieties, application

In the modern world there are a large number of varieties of steel. This is one of the most popular materials, which is used in almost all industries.

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.

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);

GOST 4543-71 will help you figure out which steels are called alloyed (structural metal). Structural low-carbon iron is manufactured in accordance with this document. Thus, the question “define alloy steels” comes down to the range of additives introduced into the metal to improve its characteristics. These are: nitrogen, chromium, silicon, boron, refractory metals. The range is complemented by nickel, copper, aluminum and other non-ferrous metals.

When considering structural alloy steels, you should pay attention to such a criterion as the total content of impurities. It sorts metal into three classes:

• highly alloyed – the proportion of additives is more than 10%;

• low impurity content - less than 2.5%.

In all cases, the mass percentage of the alloying additive is indicated.

Chemical composition is another classification factor. Classification of structural alloy steel, dividing it into high-quality, high-quality, marked with the letter “A” and electroslag remelted metal - a particularly high-quality variety with a leading “Ш” in the marking.

Similar to the quality of the chemical composition, three categories of alloy structural steel are distinguished, according to the quality of surface treatment. An additional sorting criterion in this case is the type of processing. This is, firstly, forged or hot-rolled steel, calibrated metal, as well as steel with a special surface finish.

The level of heat treatment is reflected by the marking of alloy steels. In particular, the letter “T” refers to heat-treated metal, “N” refers to cold-worked metal. The designation of alloying elements in steel is indicated after the carbon content (the first pair of numbers).

Cold-worked metal

Hardening is the hardening of metals and alloys due to changes in their structure and phase composition during plastic deformation at a temperature below the recrystallization temperature (definition from Wikipedia)

Additional designations for alloy steels indicate the following features:

1. According to the degree of deoxidation. The parameter directly depends on the percentage of silicon. Steels containing no more than 0.07% are called boiling, more than 0.12% are called calm. The interval 0.07 – 0.12% corresponds to semi-quiet grades of metal.
2. Direct marking. It is formed from several elements. The first is the letter designation B or B (group A is not designated) followed by “St”. For example, St1kp2; BSt2ps; VSt6sp3. The second is a figure corresponding to the GOST number. Third symbol: the letter “G”, the presence of which indicates a high manganese content. Next comes the degree of deoxidation of the metal and the steel category number.
3. Application. A parameter indicating where alloy structural steels are used. Markings St1, St2 are reserved for wire and rod products: nails or rivets. Fasteners are designated St3, St4, and axial elements or shafts under light load are designated St5, St6.

An alternative classification of structural steels by area of ​​use divides the metal into bearing, spring-type and heat-resistant. In the first two cases, the names speak for themselves, while the last option corresponds to a metal whose application sector is power engineering. Similar structural steels are used in the production of boilers, steam heaters or vessels.

Marking of alloy steels

In Russia and the CIS there is a brand designation system consisting of letters and numbers.

Designations of structural alloys

The marking of such steel consists of numbers and letters. The letters are the main alloying additives, the numbers after each letter show the content of the designated element, rounded to the nearest whole number (if the content of the alloying component is up to 1.5%, then the number behind the letter is not written). percentage of carbon, multiplied by 100, is written at the beginning of the name of the steel.

Marking of the main alloying components:

Element	Designation
Nickel	N
Cobalt	TO
Molybdenum	M
Chromium	X
Manganese	G
Bor	R
Copper	D
Zirconium	C
Phosphorus	P
Silicon	WITH
Niobium	B
Tungsten	IN
Titanium	T
Nitrogen	A (in the middle of the name)
Vanadium	F
Aluminum	YU
Rare earth metals	H

If steel with limited sulfur content S and phosphorus P

Source: https://tpspribor.ru/vidy-metalla/osobennosti-legirovaniya-stali.html

Classification and scope of alloy steels

The scope of application of alloy steels extends to the field of mechanical engineering. Due to their high strength and temporary resistance from 800 to 2000 MPa, they are used for the production of external structures operating at low negative and high positive temperatures, under the influence of alternating shock loads and aggressive working environments. Some types of such alloy steels are used in the reinforcement of reinforced concrete frames.

Composition of alloy steels

Alloy steels, in addition to traditional impurities, contain specific substances that are deliberately added in a regulated amount in order to ensure specific physical and mechanical characteristics. These elements are called alloying elements.

Alloying elements of steel significantly increase the strength properties of the metal, its corrosion resistance, and reduce brittleness. Among such additives, the most popular are chromium, nickel, copper, nitrogen (in a chemically bound state), vanadium, etc.

Mixing with iron, they change and destroy the symmetrical arrangement of the crystal lattice, since they have different atomic quantities and the shape of the outer electron shells.

Significant structural strength is acquired through rationalized selection of the chemical composition of alloy steel, its structure, thermal processing conditions, surface hardening methods, and increased metallurgical characteristics. The level of alloying elements content increases the cost of steel, this determines the strict validity of the range of additives.

The key role in the composition of alloy steel belongs to carbon, which increases its strength, but reduces its plastic and ductile qualities, which is why the cold brittleness threshold increases. In this regard, its content is limited within certain limits and only in exceptional cases is it higher than 60%. Based on the level of alloying, metals are classified into low-, medium- and high-alloy.

According to this classification, alloy steels in the first case contain less than 2.5% additives, in the second - 2.510%, in the third - 1050%.

In addition, a distinction is made between steel that is corrosion-resistant with respect to electrochemical and intergranular corrosion; scale- and heat-resistant surface relative to chemical decomposition at 550 °C and above; heat-resistant, which is characterized by significant heat resistance and the ability to work under load for a long time at 1000 ° C and above.

Heat-resistant high-alloy steel is a category of metal that can be used at the most critical temperatures (1/3 of the melting point) under the influence of a light load without obvious residual deformation and decay.

The main features of this type of metal are long-term plastic deformation and strength over time, which is expressed in resistance to decay under long-term influence of temperature.

Heat-resistant qualities are mainly determined by the melting point of the base element of the alloy, its alloy additive and the parameters of the previous heat treatment, which determine the structural phase of the alloy.

A significant increase in structural strength in alloyed iron is caused by high hardenability, a decrease in the critical hardening rate, and grain fragmentation. The use of strengthening heat treatment improves a number of mechanical properties. As a result of this, alloyed structural steels have improved mechanical characteristics (heat, heat and corrosion resistance) and significantly changed physicochemical and technical operational properties.

Main characteristics of alloy steels

The advantageous properties of alloy steels are the following:

• combination of significant strength and toughness parameters at positive and negative temperatures; • excellent technological qualities; • efficiency; • large production volumes; • serious parameters of resistance to plastic deformation; • alloying additives help stabilize austenite, which increases the hardenability of such steels; • the possibility of using lightweight coolers reduces the risk of defects due to cracks and warping during hardening, since the destruction of austenite is reduced; • the margin of plasticity and viscosity increases, which ensures high reliability of finished products;

• beneficial properties are revealed only after heat treatment of alloy steel, therefore manufactured products undergo a mandatory stage of thermal exposure.

An alphanumeric algorithm is used to describe alloy steel grades. Alloying additives correspond to a specific letter of the alphabet. The numbers indicated before the letters indicate the carbon level in tenths or hundredths of a percent, depending on the class of steel.

The numbers following the letters indicate the level of alloying additives as a percentage. When their level is more than 1.5%, the digital designation is not used.

Indicating the letter A at the end of the marking of alloy steels indicates that the metal is of high quality.

Low alloy steel is characterized by excellent ductility, sufficient weldability and strong resistance to brittleness. It obtains excellent mechanical qualities during hardening, normalization and further high tempering. It has a low carbon content.

High strength characteristics are obtained by introducing manganese, chromium, nickel or silicon additives. The influence of alloying elements on steel is manifested in excellent weldability and the ability to absorb mechanical stress during deformation and disintegration under impact load with a low cold brittleness limit. This steel has a fine-grained texture.

But high sensitivity to stress concentration causes reduced vibration stability.

Alloy steel welding process

The main welding parameters of low-alloy steels are their resistance to local intercrystalline cracks and brittle fracture. Indicators when choosing modes of welding operations are the maximum permissible maximum and minimum cooling rates of the heat-affected area of ​​the steel.

The maximum cooling rate is selected taking into account the prevention of cold cracks in this area. The current value of the welding process is taken in accordance with the type and thickness of the electrode, the location of the seam, the category of connection and the layer of iron being welded are also assessed.

Welding of technological zones should be carried out continuously, without cooling the seam below the initial heating temperature and preheating it above 200 °C before further passage.

Gas welding of such steels is characterized by a high degree of heating of the welded edges, low corrosion resistance and strong burnout of alloying elements, which significantly worsens the properties of the welded joints. To prevent negative moments during such welding, filler wire is used, forging at 800 °C with further normalization.

Structural low-alloy steels are used for the production of welded devices for various purposes. This category includes heat-resistant steel alloyed with molybdenum, tungsten or vanadium elements to increase the temperature at which the metal softens when heated and with chromium to increase heat resistance.

High-alloy steel is easily subject to intercrystalline corrosion, which precludes the use of gas welding. This connection option is allowed only if heat-resistant specimens are treated with a layer of up to 2 mm, but there is still a risk of warping.

Submerged arc welding of high-alloy steel is the optimal way to join metal up to 5 cm thick, since the processing ensures stable characteristics of the sheet composition throughout the entire seam.

Most alloyed tool steels belong to the pearlitic class. They contain a small number of alloying substances and are excellent for compression processing and cutting.

Tool type steel is in demand in the production of cutting tools and hot deformation forms with increased wear resistance. The metallurgical industry produces a wide range of products from such materials that comply with specific GOST standards.

The main purpose of alloy steels is to produce hot-rolled products.

Source: https://promplace.ru/vidy-metallov-i-klassifikaciya-staty/legiruyushie-stali-1487.htm

Profile pipe made of structural steel 390x150 mm 25Х2Н4МА GOST 8645 rectangular – KMI Company, LLP

Description

A steel rectangular pipe is an elongated product with a hollow profile of a constant rectangular cross-section. The profile pipe complies with GOST 8645 and is made of structural alloy steel.

Features of pipe material GOST 8645

Alloy structural steel is a durable material for critical and heavily loaded mechanism elements. Steel contains from 0.25 to 0.5% carbon. Alloying the metal increases hardenability, weldability, and machinability.

The composition of steel can be determined by markings. Two numbers at the beginning of the marking indicate the carbon content in hundredths of a percent, as well as whether the steel is structural. Further, the stamps contain letters and numbers - elements and their percentages, respectively. If the content is less than one percent, then the figure is not given. If the steel is high-quality, then the letter A is placed at the end of the mark. Elements and their letter designation:

• A - nitrogen;
• P - boron;
• F - vanadium;
• G - manganese;
• D - copper;
• K - cobalt;
• M - molybdenum;
• N - nickel;
• C—silicon;
• X - chromium;
• P - phosphorus;
• R - rare earth metals;
• B - tungsten;
• T - titanium;
• Yu - aluminum;
• B - niobium.

Structural high-quality carbon steel can be easily welded, stamped and machined. Electrodes of type E42, E42A are suitable for welding. Steel is marked with numbers indicating the average content

Rectangular pipes GOST 8645 made of structural alloy steel, due to their stiffening ribs and easy-to-install shape, are widely in demand in construction, the construction of various structures, fencing, the manufacture of furniture, outdoor advertising elements, etc.

Product characteristics

Parameter	Meaning
Material	Alloy structural steel
Brand	25Х2Н4МА
Size	390x150 mm
According to sectional shape	Rectangular
By wall type	Thick-walled
NTD	GOST 8645

You can buy a pipe made of structural steel at a competitive price from stock and to order directly from KMI Company LLP

The price is determined by the volume of products, payment terms, place and method of delivery. The minimum order amount is 28,000 tenge. Please check with the sales department for the final cost.

Advantages of working with KMI Company LLP

• KAZAKHSTAN METAL INDUSTRIAL COMPANY is part of a large international holding company operating in Russia, Kazakhstan, China, Uzbekistan and Kyrgyzstan for more than 10 years.
• Thanks to our network of warehouses in different countries, we offer the most favorable conditions for purchasing rolled metal products.
• We have created an extensive system of working with the largest manufacturers of metal products and have streamlined logistics so that you save time and money.

This price list is for informational purposes only and under no circumstances is it a public offer as defined by the provisions of Art. 447 of the Civil Code of the Republic of Kazakhstan.

Source: https://all.biz/uz-ru/truba-profilnaya-iz-konstrukcionnoj-stali-390h150-g3153556KZ

Alloyed structural steels, their grades and applications - Metals, equipment, instructions

Alloy steels are widely used in tractor and agricultural engineering, in the automotive industry, heavy transport engineering, and to a lesser extent in machine tool building, tool and other types of industry. This steel is used for heavily loaded metal structures.

Steels in which the total amount of alloying elements does not exceed 2.5% are classified as low-alloy, those containing 2.5-10% are alloyed, and more than 10% are high-alloy (iron content more than 45%).

Low-alloy steels are most widely used in construction, and alloy steels are most widely used in mechanical engineering.

Alloyed structural steels are marked with numbers and letters. The two-digit numbers given at the beginning of the brand indicate the average carbon content in hundredths of a percent; the letters to the right of the number indicate the alloying element. For example, steel 12Х2Н4А contains 0.12% C, 2% Cr, 4% Ni and is considered high quality, as indicated by the letter A at the end of the grade.

Construction low alloy steels

Low alloyed steels are those containing no more than 0.22% C and a relatively small amount of non-deficient alloying elements: up to 1.8% Mn, up to 1.2% Si, up to 0.8% Cr and others.

These steels include steels 09G2, 09GS, 17GS, 10G2S1, 14G2,15HSND, 10KHNDP and many others. Steels in the form of sheets and sections are used in construction and mechanical engineering for welded structures, mainly without additional heat treatment. Low-alloy low-carbon steels are well welded.

For the manufacture of large diameter pipes, steel 17GS is used (0.2 = 360 MPa, v = 520 MPa).

Reinforcing steels

To reinforce reinforced concrete structures, carbon or low-carbon steel is used in the form of smooth or periodically shaped rods.

Steel St5sp2 -в=50MPa,0.2=300MPa,=19%.

Cold forming steels

To ensure high formability, the ratio w/0.2 steel should be 0.5-0.65 at at least 40%. The stampability of steel is worse the more carbon it contains. Silicon, increasing the yield strength, reduces the formability, especially the ability of steel to be drawn. Therefore, for cold stamping, cold-rolled boiling steels 08kp, 08Fkp (0.02-0.04% V) and 08Yu (0.02-0.07% Al) are more widely used.

Structural (machine-building) cemented (nitro-carburized) alloy steels

For the manufacture of parts strengthened by carburization, low-carbon (0.15-0.25% C) steels are used. alloying elements in steels should not be too high, but should provide the required hardenability of the surface layer and core.

Chromium steels 15X, 20X are intended for the manufacture of small products of simple shape, cemented to a depth of 1.0-1.5 mm. Chromium steels, compared to carbon steels, have higher strength properties with some lower ductility in the core and better strength in the cemented layer, are sensitive to overheating, and have low hardenability.

Steel 20X - в=800MPa, 0.2=650MPa, =11%, =40%.

Chrome vanadium steels. Alloying with chromium steel vanadium (0.1-0.2%) improves the mechanical properties (steel 20HF). In addition, chrome vanadium steels are less prone to overheating. Used only for the production of relatively small parts.

Chromium-nickel steels are used for large parts of critical importance that experience significant dynamic loads during operation. Increased strength, ductility and viscosity of the core and cemented layer. Steels are insensitive to overheating during prolonged carburization and are not prone to oversaturation of surface layers with carbon

Steel 12Х2Н4А -в=1150MPa,0.2=950MPa,=10%,=50%.

Chrome-manganese steels are used in many cases instead of expensive chromium-nickel steels. However, they are less resistant to overheating and have lower viscosity compared to chromium-nickel ones.

In the automotive and tractor industries, and in machine tool construction, 18KhGT and 25KhGT steels are used.

Steel 25KhGM -v=1200MPv,0.2=1100MPa,=10%,=45%.

Chrome-manganese-nickel steels. Increasing the hardenability and strength of chromium-manganese steels is achieved by additional alloying them with nickel.

At VAZ, steels 20KhGNM, 19KhGN and 14KhGN are widely used.

After carburization, these steels have high mechanical properties.

Steel 15KhGN2TA -в=950MPa,0.2=750MPa,=11%,=55%.

Boron alloyed steels. Boron increases the hardenability of steel and makes steel sensitive to overheating.

In industry, 20KhGR steel and 20KhGNR steel are used for parts operating under friction wear conditions.

Steel 20KhGNR -в=1300MPa,0.2=1200MPa,=10%,=09%.

Source: https://spb-metalloobrabotka.com/legirovannye-konstruktsionnye-stali-ih-marki-i-primenenie/

Alloyed structural steels, their grades and applications

The scope of application of alloy steels extends to the field of mechanical engineering.

Due to their high strength and temporary resistance from 800 to 2000 MPa, they are used for the production of external structures operating at low negative and high positive temperatures, under the influence of alternating shock loads and aggressive working environments. Some types of such alloy steels are used in the reinforcement of reinforced concrete frames.

Alloy structural steels

Alloy steels are widely used in tractor and agricultural engineering, in the automotive industry, heavy transport engineering, and to a lesser extent in machine tool building, tool and other types of industry. This steel is used for heavily loaded metal structures.

Steels in which the total amount of alloying elements does not exceed 2.5% are classified as low-alloy, those containing 2.5-10% are alloyed, and more than 10% are high-alloy (iron content more than 45%).

Low-alloy steels are most widely used in construction, and alloy steels are most widely used in mechanical engineering.

Alloyed structural steels are marked with numbers and letters. The two-digit numbers given at the beginning of the brand indicate the average carbon content in hundredths of a percent; the letters to the right of the number indicate the alloying element. For example, steel 12Х2Н4А contains 0.12% C, 2% Cr, 4% Ni and is considered high quality, as indicated by the letter A at the end of the grade.

Where is alloy steel used?

Alloy steel is steel that, in addition to the usual impurities, contains elements specially introduced in certain quantities to ensure the required physical or mechanical properties. These elements are called alloying elements.

Alloying additives increase the strength and corrosion resistance of steel and reduce the risk of brittle fracture. Chromium, nickel, copper, nitrogen (in a chemically bound state), vanadium, titanium, etc. are used as alloying additives.

Alloy steel according to the degree of alloying is divided into:

• low-alloy (alloying elements up to 2.5%),
• medium alloyed (from 2.5 to 10%)
• highly alloyed (from 10 to 50%)

Marking [edit | edit code ]

Alloy steels are marked with numbers and letters indicating the approximate composition of the steel. The letter indicates which alloying element is included in the steel.

MarkingElement

G	manganese	Mn
C (from Latin “silicium”)	silicon	Si
X	chromium	Cr
N	nickel	Ni
D	copper	Cu
A	nitrogen	N
F	vanadium	V
B	niobium	Nb
IN	tungsten	W
E	selenium	Se
TO	cobalt	Co
L	beryllium	Be
M	molybdenum	Mo
R	boron	B
T	titanium	Ti
Yu (from "juvenile")	aluminum	Al
C	zirconium	Zr
P (from Latin “phosphorus”)	phosphorus	P
H	rare earth metals

The number following the letter indicates the average content of the element as a percentage. If the element contains less than 1%, then numbers are not placed after the letter. The first two digits indicate the average carbon content in hundredths of a percent; if there is one digit, then the carbon content is in tenths of a percent.

Additional designations at the beginning of the mark:

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

1. chromium content in ball bearing steels in tenths of a percent (for example, ШХ4 - Cr 0.4%);
2. in the grade of high-speed steel, the number after “P” is the tungsten content in%, and in all high-speed steels the chromium content is 4%.

The letter A in the middle of the steel grade shows the nitrogen content, and at the end - that the steel is pure in sulfur and phosphorus (the phosphorus and sulfur content in such steel does not exceed 0.03%).
Two letters A at the end - “AA” - mean that the steel is especially pure (even more pure in terms of sulfur and phosphorus).

• steel 18KhGT - 0.18% C, 1% Cr, 1% Mn, about 0.1% Ti;
• steel 38KhN3MFA - 0.38% C, 0.8-1.2% Cr; 3-3.5% Ni, 0.35-0.45% Mo, 0.1-0.18% V;
• steel 30KhGSA - 0.30% C, 0.8-1.1% Cr, 0.9-1.2% Mn, 0.8-1.25% Si;
• steel 03Kh13AG19 - 0.03% C, 13% Cr, 0.2-0.3% N, 19% Mn.

Today it is extremely difficult to overestimate the importance of metallurgical products, which are often used in construction, industry, and in the production of household appliances. However, alloy steels deserve special attention, because without them, many industries (food, oil, automotive, etc.) would not be able to fully fulfill their tasks.

A completely logical question arises: what is alloy steel? How are alloying components classified? What are the advantages of high-alloy material, and how is steel alloyed?

Description of metal

First you need to find out what this metal alloy is. So, this material is essentially an alloy of carbon and iron containing special elements that affect the physical and mechanical characteristics of the finished product. The components added to it are called alloying components. Copper, vanadium, manganese, nickel and chromium are the most common ones.

Types of alloy steel

Alloyed metal is classified according to the percentage of alloying elements in its composition:

• low alloy alloy - up to 2.5%;
• medium alloyed - from 2.5 to 10%;
• highly alloyed - from 10 to 50%.

There is another important point to consider. High-alloy steel and alloys based on it have their own classification and characteristics, and can also be used under different conditions:

• heat-resistant (heat-resistant) steels;
• resistant to corrosion.

Source: https://vi-pole.ru/gde-ispolzuetsja-legirovannaja-stal.html

Why are alloying elements introduced into steel?

• Characteristic
• Properties
• Stamps

In the modern world there are a large number of varieties of steel. This is one of the most popular materials, which is used in almost all industries.