What is alloy steel

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

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

Classification of alloy steels

Based on the carbon content of steel, it is divided into:

Depending on the total amount of alloying elements that alloy steel contains, it can belong to one of three categories:

1. low alloy (no more than 2.5%);
2. medium alloyed (no more than 10%);
3. highly alloyed (from 10% to 50%).

The properties of alloy steels are determined by their internal structure. Therefore, the classification of alloy steels implies division into the following classes:

1. hypoeutectoid - the composition contains excess ferrite;
2. eutectoid - steel has a pearlite structure;
3. hypereutectoid - their structure contains secondary carbides;
4. ledeburite - the structure contains primary carbides.

According to their practical application, alloyed structural steels can be: structural (divided into machine-building or construction), tool, and also steels with special properties.

Purpose of structural alloy steels:

• Mechanical engineering - used for the production of parts for various mechanisms, body structures, and the like. They differ in that in the vast majority of cases they undergo heat treatment.
• Construction - most often used in the manufacture of welded metal structures and are subjected to heat treatment in rare cases.

The classification of engineering alloy steels is as follows.

• Heat-resistant steels are actively used for the production of parts intended for work in the energy sector (for example, components for steam turbines), and they are also used to make especially important fasteners. Chromium, molybdenum, and vanadium are used as alloying additives. Heat-resistant steels refer to medium-carbon, medium-alloy, pearlitic steels.
• Improved steels (from the categories of medium-carbon, low- and medium-alloyed) steels, in the production of which hardening is used, are used for the manufacture of heavily loaded parts that experience variable loads. They differ in sensitivity to stress concentration in the workpiece.
• Case-hardened steels (from the categories of low-carbon, low- and medium-alloyed) steels, as the name suggests, are subject to carburization followed by hardening. They are used for the manufacture of all kinds of gears, shafts and other parts similar in purpose.

Dependence of the thickness of the cemented layer on temperature and processing time

The classification of construction alloy steels implies their division into the following types:

• Bulk - low-alloy steel in the form of pipes, shaped and sheet products.
• Bridge construction - for road and railway bridges.
• Shipbuilding cold-resistant, normal and high-strength - well resistant to brittle fracture.
• Shipbuilding cold-resistant high strength - for welded structures that will operate in low temperature conditions.
• For hot water and steam - operating temperatures up to 600 degrees are allowed.
• Low-cut, high-strength - used in aviation, sensitive to stress concentration.
• Increased strength using carbonitrite hardening, creating a fine-grained steel structure.
• High strength using carbonitrite hardening.
• Strengthened by rolling at a temperature of 700-850 degrees.

Application of tool alloy steels

Tool alloy steel is widely used in the production of various tools. But in addition to its obvious superiority over carbon steel in terms of hardness and strength, alloy steel also has a weak side - higher fragility.

Therefore, such steels are not always suitable for tools that are actively exposed to shock loads.

Nevertheless, in the production of a huge range of cutting, impact-stamping, measuring and other tools, alloy tool steels remain indispensable.

Separately, we can note high-speed steel, the distinctive features of which are extremely high hardness and red resistance up to a temperature of 600 degrees. Such steel is able to withstand heat at high cutting speeds, which allows you to increase the speed of metalworking equipment and extend its service life.

A separate category includes alloyed structural steels, endowed with special properties: stainless, with improved electrical and magnetic characteristics. Depending on what elements, as well as in what quantities, are predominantly contained in them, they can be chromium, nickel, chromium-nickel-molybdenum. They are also divided into three-, four- and more-component ones according to the number of alloying additives they contain.

Alloying elements and their influence on the properties of steels

The marking of alloy steels indicates what additives it contains, as well as their quantitative value. But it is also important to know exactly what effect each of these elements has on the properties of the metal separately.

Chromium

The addition of chromium increases corrosion resistance, increases strength and hardness, and is the main component in the creation of stainless steel.

Nickel

The addition of nickel increases the ductility, toughness and corrosion resistance of steel.

Titanium

Titanium reduces the graininess of the internal structure, increasing strength and density, improving machinability and corrosion resistance.

Vanadium

The presence of vanadium reduces the graininess of the internal structure, which increases fluidity and tensile strength.

Molybdenum

The addition of molybdenum makes it possible to improve hardenability, increase corrosion resistance and reduce brittleness.

Tungsten

Tungsten increases hardness, prevents grains from expanding when heated, and reduces brittleness when tempered.

Silicon

At contents of up to 1-15%, silicon increases strength while maintaining toughness. As the percentage of silicon increases, magnetic permeability and electrical resistance increase. This element also increases elasticity, corrosion resistance and oxidation resistance, but also increases fragility.

Cobalt

The introduction of cobalt increases impact resistance and heat resistance.

Aluminum

The addition of aluminum improves scale resistance.

Table of purpose of some types of steel

Separately, it is worth mentioning impurities and their effect on the properties of steels. Any steel always contains technological impurities, since it is extremely difficult to completely remove them from the steel composition. These types of impurities include carbon, sulfur, manganese, silicon, phosphorus, nitrogen and oxygen. Carbon

It has a very significant effect on the properties of steel. If it is contained up to 1.2%, then carbon helps to increase the hardness, strength, and yield strength of the metal. Exceeding the specified value contributes to the fact that not only strength, but also ductility begins to deteriorate significantly.

Manganese

If the amount of manganese does not exceed 0.8%, then it is considered a technological impurity. It is designed to increase the degree of deoxidation and also counter the negative effects of sulfur on steel.

Sulfur

When the sulfur content exceeds 0.65%, the mechanical properties of steel are significantly reduced, we are talking about a decrease in the level of ductility, corrosion resistance, and impact strength. Also, high sulfur content negatively affects the weldability of steel.

Phosphorus

Even a slight excess of phosphorus content above the required level is fraught with an increase in brittleness and fluidity, as well as a decrease in the toughness and ductility of steel.

Nitrogen and oxygen

When certain quantitative values ​​in the steel composition are exceeded, inclusions of these gases increase brittleness and also contribute to a decrease in its endurance and toughness.

Hydrogen

Too much hydrogen content in steel leads to increased brittleness.

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

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/

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

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.

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. Steel metallurgy 6 - low alloy steels

Low alloy steel grades Link to main publication

Source: https://metalloy.ru/stal/nizkolegirovannaya

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.

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

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.

More articles from this section: Low-carbon steel and its main characteristics

Low-carbon steel is an alloy that does not contain alloying elements and has

( 1 vote, average: 4 out of 5) Cast iron

Cast iron is an iron-carbon alloy. Percentage of carbon content (C) in

( 1 vote, average: 4 out of 5) Anti-friction cast iron, its properties, features, varieties and technical characteristics

Anti-friction cast iron is a casting iron that is used in critical

( 1 vote, average: 4 out of 5) Pig iron

Cast iron, which is intended for subsequent conversion into steel or smelting

( 1 vote, average: 5 out of 5) Carbon steel

Carbon steel is a tool steel containing 0.04-2% carbon

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

High carbon steel is steel that contains an increased amount of carbon,

( 1 vote, average: 5 out of 5) Grades of high-alloy cast iron

All grades of high-alloy cast iron have their own characteristic features, therefore they are used

( 1 vote, average: 5 out of 5) Nodular cast iron

Nodular cast iron is a high-strength structural material with

( 1 vote, average: 5 out of 5)

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

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.

Chemical composition

The quality of steel depends on the amount of carbon in it, which is one of the main elements included in the composition. Another essential element is iron.

Chromium, nickel, vanadium, copper and other elements are added to improve the properties of the material.

Let's take a closer look at the influence of alloying elements on the properties of steel:

• Nickel - allows you to make the material not only durable, but also ductile. It is this element included in the composition that is responsible for resistance to corrosion;
• Chromium is also responsible for resistance to corrosion, thanks to it stainless steel is obtained, making it hard and durable;
• Vanadium - thanks to this element, the steel structure becomes fine-grained and dense;
• Copper - in addition to corrosion resistance, resists acids;
• Tungsten - allows the material to remain solid when the temperature increases (heating);
• Manganese, which is part of the composition, is responsible for wear resistance;
• Silicon – makes the metal elastic, responsible for magnetism;
• If the composition includes aluminum, then it allows the material to become heat-resistant.

What happens to the structure when various impurities are added? When they are introduced, the crystal lattice collapses due to differences in the forms of electrons, as well as atomic quantities. The characteristics of steel may vary depending on the composition.

The composition may include two, three or more impurities. It depends on what kind of final product you want to get.

The composition may also include titanium, cobalt, molybdenum, which are responsible for the strength, hardness and ductility of the material, which acquires all of the listed properties mainly after heat treatment has been completed.

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.

IMPORTANT TO KNOW: How to make metal engraving with your own hands?

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.

IMPORTANT TO KNOW: How to phosphate metal at home?

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.

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.

IMPORTANT TO KNOW: Sandblasting and metal cleaning technology

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

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.

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.

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/