What is high alloy steel

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/

High-alloy steels: composition, classification, application | Useful articles about rolled metal

Special steels and alloys are distinguished either by their chemical composition or by the method of manufacturing and processing. Based on the chemical content, steels with a sufficient amount of alloying elements should be classified as special.

Fundamentally alloy steel is a human creation. In addition to carbon and natural impurities, metallurgists enrich the alloy with various chemical additives in a certain amount in order to obtain raw materials with the desired properties.

Thus, according to standard 5632-72K, high-alloy steels include alloys where the share of iron by weight is more than 45%. In this case, the upper limit of the total or total mass fraction of additives is not less than 10%. The lower limit of the mass fraction of one of the alloying elements is 8%.

Depending on the chemical composition, special steel is classified into classes according to its dominant component. So, alloys are divided into:

• iron-nickel base;
• nickel base.

Two chemical elements - nickel and chromium - are unique in their kind. When combined in the alloy in certain proportions, they give the latter elastic properties and corrosion resistance.

Steels of the first group are a solid solution in structure. Nickel and iron here are more than 65% (with the ratio of the former to the latter being 1:1.5).

Nickel-based special steels include raw materials with a predominant proportion of nickel - at least 50%. The structure is also a solid solution; chromium and selected alloying elements are present here.

Alloying Additives Mission

High alloy steels contain:

• carbon;
• silicon (provides elasticity);
• manganese (provides hardness);
• titanium (promotes the removal of nitrogen and the formation of a dense structure, is responsible for heat resistance);
• molybdenum (affects heat resistance);
• vanadium (strengthens the structure);
• tungsten (prevents grain growth, strengthens the molecular lattice);
• cobalt (increases mechanical strength).

In steels of this group, the content of sulfur, aluminum, phosphorus, boron, niobium, and copper is permissible.

High-alloy special steels and alloys are classified according to their structure into:

• martensitic and austenitic-martensitic;
• ferritic and austenitic-ferritic;
• austenitic.

In terms of properties, consumers are interested in:

• heat resistant;
• heat resistant;
• stainless (corrosion resistant).

The table below provides information about well-known grades of high-alloy steels and describes the chemical composition.

Application of high alloy steel

The metallurgy of special steels is developing. Rolled metal and structures made from high-alloy alloys are distinguished by special characteristics; they are planned to be purchased for work in extremely aggressive environments.

Experts note the greatest demand for products of this difficult rank in the oil and chemical industries, energy, and mechanical engineering.

Our company, cooperating with large Russian factories, sells rolled products made from various raw materials, including structural, alloyed and high-alloy alloys.

We guarantee low prices, will gladly accept orders and deliver purchases to addresses in St. Petersburg, Leningrad region, and regions.

Source: https://spb-stal.ru/stati/vysokolegirovannye-stali-sostav-klassifikatsiya-primenenie/

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/

Features of alloy steel - varieties, application

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

What is alloy steel

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

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

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

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

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

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

Structural alloy steels

Thick-walled structural steel pipes

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

• percentage mass of alloying elements;

• chemical composition and base admixture;

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

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

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

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

• low impurity content - less than 2.5%.

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

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

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

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

Cold-worked metal

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

Additional designations for alloy steels indicate the following features:

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

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

Marking of alloy steels

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

Designations of structural alloys

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

Marking of the main alloying components:

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

If steel with limited sulfur content S and phosphorus P

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

Marking of high-alloy steel, interpretation and features of alloying

By adding various chemical elements to alloys (alloying), their individual characteristics can be improved. For example, scale or corrosion resistance, malleability, heat resistance and a number of others. High-alloy steels include those in which the content of at least one of the additives exceeds 5%.  

All the necessary information about the product can be obtained from its designation, if you know how to correctly decipher the marking of high-alloy steel. This article will tell you about this.

Detailed data on the proportional composition of chemical elements, classification into groups of all grades of high-alloy steels are reflected in GOST No. 5632 of 1972. It also provides recommendations for their use.

Decryption procedure

Positions in the notation, from left to right.

• 1st – C (carbon) content, expressed in hundredths of a percent.
• 2nd – chemical element providing alloying.

Aluminum	Al, Yu	Copper	Cu, M	Vanadium	V, F
Chromium	X	Nitrogen	N, A	Tungsten	W, V
Niobium	Nb, B	Bor	V, R	Silicon	Si, C
Zirconium	Zr, C	Cobalt	Co, K	Tantalum	Ta
Selenium	Se, E	Iron	Fe, F	Titanium	Ti, T
Nickel	Ni, N	Molybdenum	Mo, M	Manganese	Mn, G

3rd – percentage of alloying additive in steel. If it is equal to or less than 1, then the number is not entered.

Examples of marking of high-alloy steels

 8Х18Н10Т – carbon (0.08), chromium (18), nickel (10), titanium (1).

 38Х12МУА – carbon (0.38); chromium (12); molybdenum and aluminum - 1% each. The last letter (A) indicates the high quality of the steel.

What properties do alloying elements impart to steel?

Many of the additives are similar in their effect on the material. For example, they increase its strength and corrosion resistance. Therefore, we note only those characteristics of steel on which a specific additive has the maximum impact. That is, it significantly improves them.

• Titanium – heat resistance; also promotes compaction of the structure by removing excess nitrogen.
• Cobalt – mechanical strength.
• Vanadium, tungsten, molybdenum - prevent grain growth and contribute to the invariability of the structure of high-alloy steel. Its cutting ability increases. In addition, Mo has a positive effect on the heat resistance of the material.
• Nickel – increases elasticity and rust resistance.
• Chromium – imparts many properties. In addition to those listed above, it ensures that steel is not susceptible to abrasion and its high-quality calcination.
• Manganese – hardness. However, as the temperature increases, the grain increases in size. This has a negative impact on impact strength.
• Silicon – gives steel elasticity.

One of the features of processing high-alloy steels is their hardening technology. It is produced not in water, but in oil.

Source: https://ismith.ru/metal/markirovka-vysokolegirovannoj-stali/

High-alloy steel - grades, characteristics, application

High-alloy steel, in addition to the main components - iron and carbon, also contains a number of additional additives, their total amount exceeds 10%. Alloying additives that are added to such steels are intended to significantly improve the physical as well as mechanical properties of the base alloy.

High alloy steel has excellent anti-corrosion properties

Types of steels with alloying additives

According to the provisions of the relevant GOST (5632-72), high-alloy steels are divided into two large categories: nickel-based and iron-nickel alloys. Alloys of the first category have a base containing at least 50% nickel.

In addition to nickel, the structure of such alloys, which are essentially a solid solution, contains chromium, as well as other elements. The structure of iron-nickel steels is based on iron and nickel, of which the alloy contains a total of more than 65%, and it also contains solid solutions of chromium and a number of other improving additives.

The amount of nickel and the mass fraction of iron in alloys of the second category is in an approximate ratio of 1:1.5.

High-alloy alloys are also classified according to the main characteristics they possess. So, they distinguish:

• scale-resistant steels, also called heat-resistant steels; a distinctive feature of such steels, products from which are used in an unloaded or lightly loaded state, is their increased resistance to chemical destruction of their surface layer at an external gaseous temperature exceeding 550 degrees;
• corrosion-resistant steels, also called stainless steels, are highly resistant to various types of corrosion: intergranular, salt, acid, alkaline, atmospheric, chemical, electrochemical, as well as corrosion developing under the influence of electrical voltage;
• heat-resistant, which differ from heat-resistant in that products made from these high-alloy steels are capable of operating at high ambient temperatures in a loaded state for a specified period of time.

Basic properties of common heat-resistant steels

Steels with a high content of alloying elements in their composition are also divided into several categories, depending on the nature of their internal structure. So, depending on the characteristics of the basic internal structure, they are classified into the following classes:

• martensitic, the main structure of which is formed by martensite;
• martensitic-ferritic: their structure contains martensite and, accordingly, ferrite (at least 10%);
• ferritic: their structure is formed by ferrite;
• austenitic-martensitic: the quantitative content of austenite and martensite that forms the structure of such high-alloy steels can vary;
• austenitic-ferritic: their structure is formed by austenite and ferrite, of which they contain more than 10%;
• austenitic: the structure is formed only by austenite.

It should be borne in mind that the classification of high-alloy steels according to the nature of their structure is quite arbitrary, and it is not even used to reject steel products if there are deviations from it in their structure.

High-alloy steel is assigned to one or another structural class depending on what basic structure is formed in it after the product is heated to a high temperature and cooled in the open air.

Conformity table between Russian and foreign standards - GOST (Russia), EN (Europe), AISI (USA) (click to enlarge)

Properties of certain types of high-alloy steels

Due to their unique characteristics, which can be formed by changing the chemical composition of the alloy, steels with a high content of alloying additives have found wide application in almost all sectors of modern industry.

Among the wide variety of types of high-alloy alloys, the most widely used are steels whose internal structure is based on austenite. The basic elements of the chemical composition of such steels are nickel, which they contain at least 8%, as well as chromium, the content of which exceeds 18%.

By varying the amount of other alloying additives in the composition of such steels, grades of alloys with the required characteristics are obtained.

Chemical composition of some alloy steels

Heat-resistant steels, which additionally contain tungsten and molybdenum (up to 7%), as well as boron, which is necessary to refine the grain of their internal structure, do not change the original mechanical characteristics even after being in a heated state for a long time.

A distinctive feature of high-alloy steel grades classified as corrosion-resistant or stainless steel is the low carbon content in their chemical composition (up to 0.12%).

Such steels, in addition to alloying with appropriate additives, are subjected to special heat treatment.

Thanks to this technological technique and the properties of the elements that form the composition of steels, they become very resistant to aggressive environments: acidic, salt, alkaline, gas, etc.

The influence of alloying elements on the properties of steel

Heat-resistant steels, which are able to withstand elevated ambient temperatures in an unloaded state, obtain their properties due to the fact that aluminum (up to 2.5%) and silicon are additionally introduced into their composition, due to which dense and durable materials are formed on the surface of products made from such alloys. oxides Such oxides become a kind of film that reliably protects the surface of the steel product from interaction with a heated gas environment.

In order to form the required mechanical characteristics (strength and ductility) of products made from high-alloy steels, they are subjected to special heat treatment, which consists of two stages:

• hardening, which involves heating the alloy to a temperature of 1150 degrees and its subsequent rapid cooling in water;
• stabilizing tempering, which involves heating high-alloy steel to a temperature of 850 degrees and its subsequent cooling in the open air to room temperature.

The final properties of a product made from a certain grade of high-alloy steel depend both on its chemical composition and on the modes and types of heat treatment used.

High alloy structural steel

Areas of application of products

The most popular brands of high-alloy alloys, belonging to different classes according to their structure, include:

• martensitic, which is characterized by the following chemical composition: chromium - 8-19%, manganese - no more than 1.2%, silicon - 0.6-3%, carbon - 0.12-0.7%; these are 07Х16Н4Б, 20Х17Н2, 65Х13, 13Х11Н2В2МФ, 25Х13Н2, 20Х17Н2, 11Х11Н2В2МФ, 40Х10С2М, 30Х13, 15Х11МФ, 40Х9С2, etc.;
• ferritic alloys, characterized by the following composition: chromium - 12-30%, manganese - up to 0.8%, silicon - 0.8-2%, carbon - 0.07-0.15%; these are 08Х18Тч, 12Х17, 15Х28, 10Х13СУ, 15Х25Т, 08Х17Т, 08Х13, etc.;
• martensitic-ferritic, having the following chemical composition: chromium - 11-18%, manganese - 0.5-0.9%, silicon 0.4-0.8%, carbon - 0.12-0.22%; these are 12Х13, 14Х17Н2, 15Х12ВНМФ, etc.;
• austenitic-martensitic, the composition of which contains: chromium - 14-18%, manganese and silicon - up to 0.8%, carbon - 0.05-0.9%; these are 07Х16Н6, 08Х17Н5М3, 08Х17Н6Т, 09Х15Н8У1, etc.;
• austenitic-ferritic, containing the following elements: chromium - 19-25%, manganese - 0.5-9%, silicon - 0.8-4.5%, carbon - 0.08-0.2%; these are 15Х18Н12С4ТУ, 12Х21Н5Т, 03Х22Н6М2, 03Х23Н6, etc.;
• austenitic, which includes: chromium - 10-19%, nickel - 2.8-25%, manganese - 0.6-15%, silicon - 0.4-0.8%, carbon - 0.05-0 .21%; these are 12Х18Н12Т, 20Х25Н20С2, 31Х19Н9МВБТ, 45Х14НМВ2М, 08Х10Н20Т2, 12Х25Н16Г7АР, etc.

To understand how important steels with a high content of alloying elements are in modern industry, we can give examples of the areas of application of individual grades of such alloys.

The popular grade 12X17 steel is widely used for the production of kitchenware and household items. A limitation of the use of such steel is that products made from it cannot be joined by welding.

Physical characteristics of steel grade 12Х17

High-alloy steel grades 12Х13, 08Х13 and 20Х13 are used to make parts of hydraulic devices, products that are subjected to shock loads during operation and operating in mildly aggressive environments.

Steel grade 95X18 has excellent wear resistance, so ball bearing elements for critical installations, bushings, knives and other tools are made from it.
30Х13 and 40Х13 are grades of high-alloy steels, from which compressor valve plates, parts of automobile carburetors, springs for various purposes, measuring and medical instruments are made.

This is just a small list of applications in which it is simply impossible to do without the use of high-alloy steels due to their unique characteristics.

Source: http://met-all.org/stal/vysokolegirovannaya-stal-marki-harakteristiki.html

High alloy steel

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

High-alloy steel contains from 10 to 50% alloying elements, which are introduced in order to impart the necessary physical and mechanical properties to the alloy. Alloying additives impart special resistance to corrosion, increase strength, and reduce the risk of brittle fracture. For the most part, the alloying elements of high-alloy steel are:

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

There are several types of high-alloy steels and this variety serves specific conditions in the design process. The purpose of creating a large number of alloy grades is the most accurate selection to create more advanced structures and mechanisms capable of withstanding the necessary loads. According to their properties, high-alloy steels are:

• heat resistant;
• corrosion-resistant;
• heat resistant.

This steel is very ductile, can be welded quite well, and is resistant to deformation under mechanical loads. Engineering steel has good elasticity and is non-magnetic. Of course, this is achieved through heat treatment and the introduction of the necessary alloying element, thanks to which it is possible to change the structure of the steel giving the necessary operational parameters.

High alloy steel grade

The grade of high-alloy steel in its short name contains a fairly long description of the composition, since such steel has many alloyed components. The technology for marking high-alloy steels is as follows: letters indicate the presence of an element that is present, and the number indicates the average percentage content of this element. For example, marking 40Х9С2 means:

• 0.35-0.45% C;
• 8.0-10.0% chromium;
• 2.0-3.0% silicon.

The grade of high-alloy steel shows the classification of the type of steel and allows you to accurately determine the best purpose for the alloy. There are several main classes:

• chromium;
• chromium-nickel;
• chromium-manganese steels.

Belonging to a certain class is reflected in the marking.

Grade 06Х16Н15М3Б is used for the manufacture of products subject to very high temperatures and loads - these are high-pressure steam pipelines and superheater pipes. Brand 08Х15Н24В4ТР is used for guide and working blades, fasteners, disks of long-term gas turbines at temperatures of 650-700%.

Grade 08Х16Н9М2 is used for the manufacture of reduced seamless pipes that have been subjected to cold deformation, thermal deformation, and hot pressing; these pipes are intended for steam boilers and pipelines of installations experiencing supercritical steam parameters.

High-alloy steel grade - 12Х8ВФ, is actively used for stove pipes, communications and equipment of oil plants, as well as structures and mechanisms designed to operate at temperatures of 5000C.

Properties of high alloy steels

The properties of high-alloy steels characterize them as a durable and at the same time ductile material. The alloy also combines corrosion and deformation resistance. If we compare this steel with carbon steel, high-alloy steel has significantly greater ductility. Without exception, all alloyed alloys can be used to create structures connected by welding seams.

High rates of metal weldability make it possible to achieve maximum strength of welds; therefore, steel is used for welded structures operating under high mechanical loads. Certain engineering grades are also distinguished by their non-magnetic properties, elasticity and increased thermal hardening. High mechanical strength is achieved through heat treatment of the alloy.

The listed properties of high-alloy steels allow them to be actively used in various fields of activity.

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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.

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.

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.

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.

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

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.

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.

High carbon alloy steel

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. Steel metallurgy 6 - low alloy steels

Low alloy steel grades Link to main publication

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

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