Low alloy steel what is it

Low alloy steel: main characteristics | Useful articles about rolled metal

Low-alloy steel gained popularity in the post-war years: according to statistics, its production increased 17 times between 1955 and 1970! Today its share in the total volume of steel produced is 13%.

This type of raw material is characterized by the content of alloying additives, thanks to which the steel acquires increased (improved) mechanical properties.

Structural low-alloy steels are saturated with nickel, chromium, and molybdenum to increase their hardenability. The process actively contributes to the optimization of viscosity and plasticity properties. In some cases, raw materials are alloyed to improve resistance characteristics.

The share of alloying elements in low-alloy steels is no more than 2.5%. Each element has its own influence on the properties of the raw material and, consequently, on the products made from it.

Classification

It is worth noting a wide range of low-alloy alloys. With a variety of chemical composition and processing options, they are quite broadly classified:

• and by chemical composition;
• and according to the heat treatment option;
• and according to the degree of weldability.

It is convenient for buyers to navigate based on the formation of alloys into 4 fairly large groups. This:

• so-called low-alloy martensitic steels;
• medium carbon high strength;
• heat-resistant (chromolybdenum);
• ball bearing.

The most popular today are low-alloy steel grades such as: 09G2, 09G2S, 17G1S, 0HSND, 16G2AF. Steels 10KhNDP, 15KhNDP, 15KhSND, 0KhSND are known as atmospheric corrosion-resistant (AKS). There are also substitutes. For example, instead of 09G2S they use 09G2, 09G2T or 09G2DT, instead of 10G2S, 10HSND - 16GAF).

Name and marking

In the name of steels, alloying components are indicated in descending order of their content (for example, chromium-molybdenum, chromium-silicon-manganese, chromium-nickel).

The marking contains both letters and numbers. The letters correspond to chemical alloying elements, the numbers, respectively, to their “% presence”. The most famous additives are:

Marking Element

X Cr – chromium

M Mo – molybdenum

Н Ni – nickel

C Si – silicon

D Cu – copper

In W – tungsten

Yu Al – aluminum

G Mn – manganese

T Ti – titanium

B Nb – niobium

K Co - cobalt

The initial numbers tell about the carbon content (tenths or hundredths). If the brand begins with a letter designation, then its share in the alloy composition is from 1% and higher. So, for example, 18ХГТ steel consists of 0.18% carbon and chromium, manganese, titanium (the share of each does not exceed 1%).

Sometimes at the beginning of the marking there are auxiliary symbols that characterize the purpose of the raw material: A - automatic steel, P - high-speed cutting, Ш - ball bearing, etc.

Welding Features

Steels of this type are characterized by good weldability. For the manufacture of products and metal structures, various technologies and welding options are used, including:

• electro-;
• gas;
• electroslag.

Like any work, welding low-alloy steels, each method has its own characteristics. There are a number of recommendations for optimizing modes, choosing technical conditions, and the necessary tools (electrodes).

Range and application

Low alloy steel is widely used today in many sectors of the economy. This includes construction, transport production, and agriculture.

In construction, products made from low-alloy carbon and low-carbon steels allow you to save metal and significantly reduce costs. At the same time, experts note the high reliability, structural strength, resistance to deformation and temporary wear of the objects being built.

Thus, low-alloy chromium-silicon-nickel-copper steel 15KHSND (GOST 5058-65) and steel 10KHSND, due to their good weldability and corrosion resistance, are indispensable for the installation of reliable welded metal structures, which is extremely in demand in shipbuilding.

For laying gas pipelines, erecting bridges, and other critical structures, silicon-manganese steel 10G2S1 (MK) (GOST 5058-65) is used. It also resists corrosion well, has reduced cold brittleness, and satisfactory weldability.

Steam turbines, pipelines, and boilers are built using heat-resistant molybdenum, chromium-molybdenum and chromium-molybdenum-vanadium alloys, which are also resistant to severe pneumatic loads.

Chrome-silicon-manganese steels have high strength, elasticity, and good resistance to impact deformation. Their use is justified when installing many critical structures. Sheets and pipes are usually used.

Source: https://spb-stal.ru/stati/nizkolegirovannaya-stal-osnovnye-kharakteristiki/

Alloy 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.

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.

This type includes steel materials, the amount of alloying additives in which exceeds ten percent. The amount of these components in such steel can reach fifty percent.

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: http://lkmprom.ru/clauses/materialy/legirovannaya-stal-i-ee-osnovnye-svoystva/

Low-alloy steel, properties, technical characteristics, processing features and types of low-alloy alloys

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Nikolaenko Dmitrij

Low-alloy steel, properties, technical characteristics, processing features and types of low-alloy alloys Low-alloy steel, properties, technical characteristics, processing features and types of low-alloy alloys ( 1 vote, average: 5 out of 5)

Low alloy steel contains alloying elements in small quantities, hence the name. Alloying components include chromium, nickel, molybdenum, etc., which give it special properties.

Thanks to the above elements, low-alloy steel acquires better strength, becomes more malleable and resistant to corrosion, although it remains quite vulnerable to weathering.

Alloying elements in the alloy composition should be less than 2.5% of the total volume, not counting carbon.

Low alloy steel grade

Low-alloy steel grades , which indicate the chemical composition of the alloy, are produced in a large number of types and names. The metal marking technology is structured as follows: the number before the letter corresponds to the average carbon content in steel in hundredths of a percent. The letters respectively indicate the name of the alloying element:

• G-manganese;
• C - silicon;
• X-chrome;
• N-nickel, etc.

If the component in the composition is less than 0.3% of the total volume of the material, then it is not included in the designation. Such steels have better mechanical properties, higher wear resistance, and better weldability than carbon steels, but all these grades require protection against corrosion.

Low-alloy steels grades 10ХСНД, 10ХНДП, 15ХСНД contain copper and tin alloying them, have excellent resistance to atmospheric influences, therefore they are used for building structures, power transmission supports, etc. Brands such as 18G2S, 25G2S are used in reinforced concrete structures as reinforcement.

Grades 16GS, 09G2S, containing silicon and manganese, are highly durable and very reliable; they are successfully used in the chemical industry. These steels have good ductility, toughness and weldability.

Low alloy steel application

Low-alloy steel, the use of which is quite extensive due to the combination of a number of positive characteristics. Thus, the mechanical strength of steel makes it possible to reduce the weight of structures, sometimes up to 30%, by using various rolled products.

In addition, the use of low-alloy steels makes it possible to increase structural reliability and service life, while reducing their cost.

Due to the good balance of alloying elements, the thickness of products is significantly reduced, so low-alloy steel is used in shipbuilding, main pipelines, bridge construction, and is also used in reinforced concrete plants to ensure the rigidity of reinforced concrete structures, for the manufacture of pressure vessels, mine equipment, earthmoving equipment, etc.

Marking of low alloy steels

The marking of low-alloy steels has letters and numbers. The letter indicates the alloying element contained, and the number indicates the average content of the element. Example: 18ХГТ alloy contains:

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

Low alloy steel grades may have additional designations:

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

Low alloy steel processing

Treatment of low-alloy steel can be thermal, to give the alloy increased strength, ductility, resistance to low temperatures and good corrosion resistance. For example, oil and gas pipeline pipes require special strength properties.

Processing of low-alloy steel can be mechanical-thermal. In this case, the workpiece undergoes cold forging and subsequent annealing. During forging, the necessary fine grain and nanocrystalline state are obtained, and annealing produces the necessary recrystallization processes with the appearance of a dispersed structure.

This procedure allows you to correct the smallest defects in the microstructure of the alloy and increases the resistance to brittle fracture.

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

Difference between low alloy steel and high alloy steel

The main difference between low alloy steel and high alloy steel is that low alloy steels contain less than 0.25% alloying element, whereas high alloy steels have more than 10% alloying element .

In addition to dividing into low-alloy and high-alloy steel, it is also divided according to the degree of alloying into medium-alloy. In this steel, the amount of alloying elements ranges from 2.5 to 10%)

An alloy is a mixture of two or more elements. It is produced by mixing a metal with some other elements (metals or non-metals or both) to produce a material that has improved properties over the original metal. Low alloy steel and high alloy steel are two types of iron alloys with alloying elements.

The most popular alloying elements in these steels are: nickel (Ni), copper (Cu), titanium (Ti) and vanadium (V), nitrogen (N), etc.

1. Overview and main differences
2. What is low alloy steel
3. What is high alloy steel
4. What is the difference between low alloy steel and high alloy steel
5. Conclusion

What is low alloy steel?

Low alloy steel is a type of alloy steel whose properties are improved compared to carbon steel. For example, this alloy has better mechanical properties and greater corrosion resistance than carbon steel. carbon in low alloy steel is less than 0.2%. The most common alloying elements in this steel are: Nickel (Ni), Chromium (Cr), Molybdenum (Mo), Tungsten (V), Boron (B), Tungsten (W) and Copper (Cu).

Sheet steel

In most cases, the manufacturing process of these alloy steels includes heat treatment and tempering (for normalization). But now, there is a tendency to harden and temper. In addition, almost all low alloy steel materials are weldable. However, the material sometimes requires treatment before or after welding (to avoid cracking).

Some advantages of low alloy steel:

1. Yield strength is higher
2. High tensile strength
3. Higher resistance to oxidation and corrosion
4. Low cold brittleness threshold

Source: https://raznisa.ru/raznica-mezhdu-nizkolegirovannoj-stalju-i-vysokolegirovannoj-stalju/

Application of alloy steels. Classification and marking of alloys

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.

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.

Marking of alloy steels

Due to the wide variety of alloys with improving additives, there is a need for their labeling. Alloy steels, the classification and marking of which will be given below, are very easy to identify by letter designation, as well as by indicating the percentage composition of certain substances in the metal.

Decoding

The marking includes letters that indicate the purpose of the metal.

1. Zh, X, E - designation of stainless, chromium and magnetic alloys.
2. I am chromium-nickel stainless steel.
3. Ш - ball bearing.
4. R - cutting.
5. A, Sh - high-quality and high-quality alloy steel.

Alloys may also contain the following elements:

• Nitrogen - A
• Aluminum - U
• Beryllium - M
• Bor - P
• Tungsten - B
• Vanadium - F
• Cobalt - K
• Silicon - C
• Manganese - G
• Copper - D
• Molybdenum - M
• Magnesium - Sh
• Niobium - B
• Nickel - N
• Selenium - E
• Titan - T
• Phosphorus - P
• Chrome - X
• Zirconium - C
• Rare earth metals - H

If alloy steels whose markings do not have numbers after the letters do not contain niobium, molybdenum, vanadium, aluminum, nitrogen, boron, titanium, zirconium and rare earth metals, then this will indicate that the alloying element content in the material is less than 1.5%. For the metals listed above, there is an exception to this rule, due to the influence of even tenths of a percent on the mechanical properties of the alloy.

If there is a number in front of the letter designation, then this is an indicator of silicon content, and the arrangement of numbers after the letter indicates the percentage of the designated chemical elements.

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.

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.

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.

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.

(3 4,67 out of 5)

Source: https://plavitmetall.ru/obrabotka/legirovannaya-stal-primenenie.html

Low-alloy structural steel for welded structures

Low-alloy steels contain from 0.2% C and up to 2-3% of mostly non-deficient alloying elements.

They are not much more expensive than carbon ones, but have a number of important advantages: a higher yield strength, which allows reducing metal consumption by 15-30%; reduced susceptibility to mechanical aging; increased cold resistance, better corrosion resistance and wear resistance; the ability to significantly increase, after quenching and tempering, strength, toughness, wear resistance and notch sensitivity. All this, combined with good weldability, has led to the widespread use of these steels in the manufacture of pipelines and apparatus, all kinds of welded structures in carriage building, automotive industry, agricultural engineering, etc.

The steels are not flake-sensitive and are not prone or have little tendency to temper brittleness. When using high-strength non-pearlite and low-pearlite steels with a very low content of carbon, sulfur and phosphorus, which results in very good weldability, high impact strength and a low cold brittleness threshold. The high strength of steels in this case is achieved through microalloying with niobium, vanadium and titanium and the use of controlled rolling during production.

As the experience of factories has shown, the use of low-alloy steel in apparatus construction makes it possible to improve the technical and economic indicators of production and achieve significant savings in metal due to the higher yield strength of a number of grades of low-alloy steel compared to conventional carbon steel.

The use of low-alloy steel in petroleum apparatus construction allows reducing the weight of structures by up to 25%, the labor intensity of manufacturing lightweight structures by 16%, the complexity of installation work by 15% and the cost by 20%.

An alphanumeric code is used to designate grades of low-alloy steel. The numbers at the beginning of the marking indicate the carbon content in hundredths of a percent (average content), and the letters indicate what alloying element is contained in the steel. When marking steel for various alloying elements, the following designations are used:

• N - nickel
• X - chrome
• G - manganese
• M - molybdenum
• C - silicon
• B - tungsten
• F - vanadium
• T - titanium
• K - cobalt
• Yu - aluminum
• D - copper

The numbers appearing in the brand after the letters indicate the approximate content of the corresponding alloying element, if the amount of this element exceeds 1.5%.

Below is a list of grades of low-alloy structural steel:

List of low alloy steel grades

1. Steel 09G2
2. Steel 14G2
3. Steel 12GS
4. Steel 16GS
5. Steel 17GS
6. Steel 17G1S
7. Steel 09G2S
8. Steel 10G2S1
9. Steel 10G2BD
10. Steel 15G2SFD
11. Steel 14G2AF
12. Steel 16G2AF
13. Steel 18G2AFps
14. Steel 14ХГС
15. Steel 15G2AFDps
16. Steel 20ХГ2Ц
17. Steel 10HSND
18. Steel 10KhNDP
19. Steel 15HSND
20. Steel 35GS
21. Steel 25G2S

Source: http://enginiger.ru/materials/nizkolegirovannye-stali/stal-konstruktsionnaya-nizkolegirovannaya-dlya-svarnyh-konstruktsij/

Low alloy steel

Alloying is the process of introducing one or more elements into an alloy in a certain percentage. This is done to improve certain characteristics of the metal. In low-alloy steel, the total share of alloying additives does not exceed 2.5%.

The composition of the alloy can be determined by the markings. Chemical elements used for alloying have letter designations:

• nitrogen – A (in the middle);
• cobalt – K;
• titanium - T;
• tungsten - B;
• niobium – B;
• nickel – N;
• vanadium – F;
• molybdenum – M;
• copper – D;
• boron – P;
• chromium – X;
• manganese – G;
• phosphorus – P;
• zirconium – C;
• selenium – E;
• silicon – C;
• aluminum – Yu;
• rare earth elements – Ch.

The number at the beginning of the marking indicates the amount of carbon in the alloy. Expressed as a percentage, in hundredths and tenths. If there is no number, then there is more than 1% carbon. The number after the letter indicates the proportion of the alloying additive, if it is more than 1%. For example, 18ХГТ - the alloy contains chlorine (1%), manganese (1%), titanium (1%), carbon content 0.18%.

Low-alloy steel grades may contain additional letter designations:

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

For example, AS35G2 is free-cut steel, alloyed with lead, containing 0.35% carbon and about 2% manganese.

Properties of low-alloy steel depending on the type of added metals

Thanks to the introduction of alloying additives, the characteristics of the alloy can be changed:

• silicon – improves the elasticity and magnetic properties of steel, introduced in combination with manganese; silicon-manganese steels are used in bridge construction, shipbuilding, and to create building structures;
• nickel – adds ductility, strength, corrosion resistance; Nickel steels are used in metallurgy;
• chromium – improves hardness, corrosion resistance, strength; chromium steel has a wide range of applications - the manufacture of rollers and bearings, automotive industry, tractor manufacturing, etc.;
• copper – adds ductility, resistance to acids and corrosion; copper steels are used in ship, crane and bridge construction;
• tungsten, molybdenum, titanium - make the metal harder, stronger, denser and more heat-resistant; used for the production of steam pipes and turbine parts;
• cobalt – improves ductility, strength, magnetic properties; scope of application – production of magnets, cutting tools;
• vanadium – added during complex alloying, creates a uniform structure; for example, chrome vanadium steel is used for the manufacture of shafts, gears, couplings, critical springs, etc.;
• manganese - makes steel harder without reducing its ductility; manganese steels are used in the manufacture of parts for construction equipment;
• nitrogen – improves strength and heat resistance; Nitrided steels are used in mechanical engineering.

Low alloy structural steel

Low-alloy structural steel is produced in accordance with GOST 19281-89. Depending on the properties, volume fraction of phosphorus and sulfur, it is classified into:

• ordinary quality steel (“St”) – up to 0.05% (volume of phosphorus and sulfur);
• high-quality steel (“Steel”) – up to 0.035%;
• high-quality steel (“A”, the last letter in the marking) - up to 0.025%;
• especially high-quality steel (“Ш”, the last letter in the marking) - up to 0.015%.

Low-alloy structural steel is used in carriage building, locomotive building, production of agricultural machinery and in the construction of engineering infrastructure structures that are forced to operate under the influence of temperature changes and dynamic loads.

Purchase of low-alloy rolled products from Trade House Areal LLC

The Areal trading house offers to purchase rolled products from low-alloy steel with delivery throughout Moscow, the Moscow region and the Central region of Russia. We have our own fleet of vehicles and load goods free of charge.

Our advantages:

• high quality low alloy steel. We have been cooperating with the best manufacturers in the country for more than 20 years. Products comply with domestic and international standards;
• a wide range of additional services. We select rolled products according to characteristics, cut them, stack them;
• affordable prices and individual approach. We take into account the client’s interests in the assortment, payment terms, delivery, etc.

Source: https://areal-metal.ru/spravka/nizkolegirovannaya-stal

Low alloy steel what is it?

To improve the technical characteristics of metals and alloys, a technological process called alloying is carried out.

It implies the introduction of additional additives into the composition of the material compound, which change its properties.

Depending on the percentage of additional components added, three groups of resulting materials are distinguished. Any metalworking master should know low-alloy steels and their grades.

Compound

Before you start understanding the properties, you need to know the composition of low-alloy steels. The amount of alloying additives should not exceed 5% (some sources indicate the maximum amount of additional components - up to 2.5%). Carbon is not considered an alloying component.

The most popular, inexpensive additional additives include:

1. Vanadium is responsible for the uniform structure.
2. Molybdenum - increases the resistance of the compound to high temperatures.
3. Niobium - increases strength.
4. Tungsten - increases heat resistance.
5. Titanium - increases wear resistance.
6. Nickel, silicon - increase shock resistance and current resistance.

Properties of low alloy steels

To understand the possibilities and areas of application of low-alloy materials, you need to understand their physical and chemical properties:

1. High wear resistance.
2. High corrosion resistance.
3. Improved mechanical properties.
4. High surface hardness.

Classification of alloy steels

With the development of new technologies and the emergence of different alloy steels, they needed to be classified.

Division by the amount of carbon contained in the alloy:

1. High carbon - more than 0.65%.
2. Medium carbon - from 0.25% to 0.65%.
3. Low carbon - less than 0.25%.

Separation by percentage of alloying additives:

1. Low alloyed - up to 5% (according to some sources up to 2.5%).
2. Medium alloyed - up to 10%.
3. Highly alloyed - 10–50%.

According to their internal structure, alloy steels are:

1. Eutectoid - pearlite structure.
2. Ledeburite - the presence of primary carbides in the structure.
3. Hypoeutectoid - the presence of excess ferrites saturating the composition.
4. Hypereutectoid - the presence of secondary carbides in the alloy.

Based on their purpose, these materials can be divided into two large groups:

1. Construction - for the manufacture of metal structures that will not be exposed to critical temperatures during subsequent operation.
2. Mechanical engineering - used in the manufacture of parts for various mechanisms and housings.

Engineering steels are:

1. Cemented - during manufacturing they undergo a process of carburization and then hardening.
2. Heat-resistant - medium-carbon steels. They are used in the manufacture of products used in the energy sector.
3. Improved - materials that undergo additional hardening. They are used to make parts that are subject to heavy loads.

Alloying elements and their influence on the properties of steels

Several alloying additives that are most often added to compounds have been described above. To understand how all the additional components affect the technical characteristics of the alloy, you need to understand them individually in more detail:

1. Titanium - the granularity of the structure decreases, density and strength indicators increase.
2. Sulfur - this component should not be more than 0.65% in the composition. Otherwise, corrosion resistance, ductility, and impact strength will decrease.
3. Carbon - content no more than 1.2% increases strength and hardness. If the quantity is increased, the technical parameters will decrease.
4. Phosphorus is not suitable as an alloying additive. An increase in its quantity in the composition leads to a sharp decrease in technical parameters.
5. Aluminum - to increase scale resistance, this component is added.
6. Nickel - helps to increase corrosion resistance, viscosity, and ductility.
7. Chromium - increases hardness, strength, and corrosion resistance.
8. Silicon - the content of this component should not exceed 15%. Increases electrical resistance and magnetic permeability.
9. Manganese - content up to 0.8% is considered one of the technological impurities. Reduces the negative impact of sulfur on the alloy.
10. Oxygen, nitrogen - a large number of gas bubbles in the composition makes the metal more fragile.
11. Hydrogen - metallurgists are trying to reduce the amount of this component in the composition to make the material more durable.

Marking

Metal marking carries a lot of information for buyers and people working with products. Low-alloy steel grades are indicated in accordance with GOST 4543-71. The marking is a set of letters and numbers, each of which has a specific meaning. Standard transcript:

1. The letter comes first. It determines the properties of the metal and assigns it to a certain subgroup. For example, the letter “F” indicates a stainless steel base.
2. The number following the first letter indicates the percentage of carbon in the composition. For example, 5 - 0.05%.
3. Next, alloying additives are designated according to the periodic table.
4. After the designations of additional components, numbers are indicated indicating their percentage in the compound.

Application of metal

Low alloy steels are used in various industries. Application area:

1. Manufacturing of lightweight metal structures.
2. Housings for household appliances.
3. Parts for industrial equipment.
4. Cutting tools.

Due to the high price of such materials, they are used in cases where analogues cannot cope with the tasks.

Welding

To connect parts made of low-alloy steel using welding, you need to take into account several nuances:

1. Make vertical, ceiling seams.
2. The welding rod must have a cross-section of at least 4 mm.
3. To reduce the cooling rate of the metal, it is necessary to make butt or side welds.
4. When welding workpieces with a thickness not exceeding 6 mm, only one pass is required.
5. To give the connection high ductility, you need to use E42A electrodes.
6. If the metal contains a small amount of carbon, it is necessary to use electrodes coated with fluorine and calcium.

To carry out welding work, it is necessary to use a special additive Sv-10G2.

Low-alloy steels have increased technical parameters due to the addition of additional components to the composition. They are used in those areas of industry where it is necessary to use parts and metal structures of high strength and wear resistance. To connect individual parts, you need to take into account a number of nuances of using welding equipment.

Low alloy steel grades Link to main publication

Source: https://varimtutru.com/nizkolegirovannaya-stal-chto-eto/

Alloy steels: classification and marking

Alloy steel is steel containing special alloying additives that can significantly change a number of its mechanical and physical properties. In this article we will understand what the classification of alloy steels is, and also consider their markings.

Alloy steel round bars

Use of alloy steels

Today it is difficult to find an area of ​​life and activity in which alloy steel would not be used. Almost any tool is made from tool and structural steels: cutters, milling cutters, dies, measuring devices, gears, springs, pendants, braces and much more. Stainless alloy steels are actively used in everyday life; they are used to make dishes, cases and other elements of many types of household appliances.

Due to their high cost, alloy steels are used only for the production of the most critical structures and parts, where products made from other metals simply cannot perform the tasks assigned to them.

Source: http://met-all.org/stal/legirovannye-stali-markirovka.html

Low alloy steels - definition, grades, properties

Low-alloy steels include steels with a carbon content of 0.2% and alloying elements with a total amount of up to 2.5%, examples: 09G2, 09G2S, HSND, 15HSND. Such alloys are slightly more expensive than unalloyed carbon alloys, but have a number of advantages over them.

Among them, increased ones include yield strength, cold resistance, corrosion resistance, wear resistance, and reduced susceptibility to mechanical aging.

The marking of low-alloy steels indicates numbers that indicate the carbon content in hundredths of a percent, and letters indicating which alloying elements were used in the alloy.

Classification

The group of low-alloy steels includes steels that differ in:

• Chemical composition . For alloying, various elements are used, often not scarce - nickel, molybdenum, chromium, aluminum, silicon.
• Heat treatment . The types of heat treatment used are quenching + tempering, normalizing + tempering, various types of annealing.
• Weldability . Grades with a low percentage of carbon have good weldability.

List of the most popular grades of low-alloy steels:

• 09G2S and alternative options - 09G2, 09G2T, 09G2DT, 10G2S;
• 17G1S;
• 10HSND and alternative – 16GAF.

The group of atmospheric-corrosion-resistant steel alloys (ACS) includes 10KhNDP, 15KhNDP, 15KhNDP, 15KhSND, 0KhSND.

Main characteristics

The production of low-alloy steels used in the production of high-strength long, thick sheet, strip, shaped, and pipe products is regulated by GOST 19281-89. From such metal products, welded, riveted, bolted structures are created, or products are made that do not require subsequent heat treatment.

The mechanical properties of low-alloy steels are improved by reducing the sulfur and phosphorus content. Such rolled products have good impact strength and a low threshold of cold brittleness, and, provided that the carbon content is low, they have good weldability. The strength characteristics of low-alloy steels are increased by producing rolled products using controlled rolling technology. The strength of steel alloys is also increased by microalloying with titanium, vanadium, and niobium.

Purpose of low alloy steel

The high performance characteristics of steels with alloying additives ensure their use in the following areas:

• Construction of pipeline systems for various purposes . The use of steel alloys with additions of chromium, silicon and manganese ensures high strength of structures and products, elasticity, and effective resistance to elastic deformation.
• Production of welded structures in the car, machine tool, automotive, and heavy engineering industries. These alloys are used to produce the bodies of railway and tram cars and agricultural machines.
• Petroleum apparatus engineering . The use of low-alloy steel in this area allows saving metal, reducing the weight of structures, labor costs for manufacturing and installation, and, consequently, cost.
• Construction of engineering structures that are operated under variable dynamic loads, under conditions of daily and seasonal significant temperature changes.
• Production of steam turbines . For these purposes, heat-resistant grades alloyed with molybdenum, chromium + molybdenum, chromium + molybdenum + vanadium are used. Such products are also resistant to significant pneumatic loads.

The most common grade - 09G2S - and its analogues are used in the production of rolled products capable of operating in a wide temperature range - from -70°C to +450°C.

Steam boilers, containers and devices operated at high pressure, and welded structures for critical purposes used in the chemical and oil industries and shipbuilding are made from such rolled metal.

Grade 09G2S is used in the production of hot-rolled seamless pipes, electric-welded pipes of significant diameters, and containers of significant carrying capacity.

Source: https://TreydMetall.ru/info/nizkolegirovannye-stali-info

Low alloy steel grades

To improve the technical characteristics of metals and alloys, a technological process called alloying is carried out. It implies the introduction of additional additives into the composition of the material compound, which change its properties. Depending on the percentage of additional components added, three groups of resulting materials are distinguished. Any metalworking master should know low-alloy steels and their grades.

Low alloy steel and its grades