What is an iron-carbon alloy called?

State diagram of iron-carbon alloys

It is difficult to imagine modern industry without the use of various types of metal alloys, including steel. Metallurgists in different countries are developing their compositions, but to predict the properties of future alloys, most specialists are guided by the iron-carbon diagram. It gives a clear idea of ​​how most steel alloys and cast irons are structured.

State diagram

The diagram contains a number of lines and critical points indicating the state of the melt at a certain heating.

Classification of iron-carbon alloys

Various combinations of these elements lead to a large number of alloys, which can be divided into three large groups:

1. Technical hardware.
2. Become.
3. Cast iron.

Technical hardware

Technical iron includes materials containing less than 0.02% carbon. Steels include materials in which carbon is in the range from 0.02 to 2.14%. And the cast iron group includes materials in which the amount of carbon exceeds 2.14%.

Austenite

The atoms are placed in a face-centered cell. Austenite has a hardness of 200-250 Brinell. In addition, it has good ductility and is paramagnetic.

Iron

Iron is a material classified as a metal. Its natural color is silver-gray. In its pure form it is very plastic. Its specific gravity is 7.86 g/cc. cm. Melting point is 1539 °C. In practice, industrial iron is most often used, which contains the following impurities - manganese, silicon and many others. The mass fraction of impurities does not exceed 0.1%.

Iron

Iron has such a property as polyformism. That is, with the same chemical composition, this substance can have a different crystal lattice structure and, accordingly, different properties. Modifications of iron are called respectively - B, D, D. All these modifications exist under different conditions. For example, type B can only exist at a temperature of 911 °C. Type G can exist in the range from 911 to 1392 °C. Type D exists in the range from 1392 to 1539 °C.

Each type has its own crystal lattice shape, for example, type B has a cube-shaped lattice, type G lattice has a face-centered cubic shape. The D-type lattice has the shape of a volume-centered cube.

Another property is that at temperatures below 768, iron is ferrimagnetic, and as it increases, this property is lost.

The points of polymorphic and magnetic transformation are called critical. On the table they are designated as follows - A2, A3, A4. Digital indices indicate the type of transformation. To more fully distinguish the transformation of iron from one type to another, the indices c and r are added to the designation. The first one talks about heating, the second one talks about cooling.

Iron polymorphs

With high ductility parameters, iron does not have high hardness; on the Brinell scale it is equal to 80 units.

Iron has the ability to form solid solutions. They can be divided into two groups - substitution and implementation solutions. The former consist of iron and other metals, the latter of iron and carbon, hydrogen and nitrogen.

Another component of the system is carbon. It is a non-metal and has three modifications in the form of diamond, graphite and coal. It melts at 3500 °C.

Allotropic modifications of carbon

In an iron alloy, this element is found in the form of a solid solution, it is called cementite or in the form of graphite. In this form it is present in gray cast iron. Graphite is neither ductile nor durable.

Cementite

The carbon share is 6.67%. It has high hardness - 800 HB, but at the same time it lacks ductility. Does not have polymorphic properties.

It has the following property - when forming a substitution solution, carbon can be replaced by atoms of other substances, for example, chromium or nickel. This solution is called a doped solution.

Cementite

It is not stable; under certain conditions it can decompose, and carbon is transformed into graphite. This property has found application in the formation of cast irons.

By the way, in a liquid state, iron can dissolve impurities in itself, while forming a homogeneous mass.

Ferrite

This is the name given to the solid solution in which carbon is introduced into iron.

It dissolves with a certain variability; at normal (room) temperature, the volume of carbon is within 0.006%; at 727 °C, the carbon concentration will be 0.02%. Upon reaching 1392 °C, ferrite is formed.

Ferrite

carbon will be 0.1%. Its atoms are located in defective lattice sites.

Ferrite is close in its parameters to iron.

Austenite in steels

The presence of austenite in steel alloys gives them certain properties. Parts and assemblies made from such steels are intended to work in environments containing aggressive components, for example, in enterprises processing various acids.

Steels of this class are characterized by a high level of alloying; during crystallization, a face-centered lattice is formed. This structure is not subject to change even under the influence of deep cold.

Steels of this type can be divided into two types that differ from each other in composition. Firstly, they contain substances such as iron, nickel, chromium. In this case, the total number of additives cannot exceed 55%. The second group includes nickel and iron-nickel compositions. In nickel compositions, its content exceeds 55%. In iron-nickel compositions, the ratio of nickel to iron is 1:5, and the amount of nickel starts from 65%.

This amount of nickel provides increased ductility, and chromium, in turn, provides high corrosion resistance and heat resistance. The use of other alloying materials makes it possible to smelt alloys with unique performance properties. Metallurgists, when formulating alloys, are guided by the future purpose of the steels.

To produce alloy steels, ferritizers are used, which impart constancy to austenites; such substances include niobium, silicon and some others. In addition to them, carbon and manganese are used - they are called austenizers.

Cementite: forms of existence

This is the name given to the compound of carbon and iron. It is a component of cast iron and some steels. It contains 6.67% carbon.

Its crystal includes several octahedra; they are located with respect to each other at a certain angle. Inside each of them is a carbon atom. As a result of this construction, the following picture is obtained - one atom comes into contact with several atoms of iron, and iron, in turn, is connected with three atoms of this element.

Crystal lattice of cementite

This substance has all the properties that are inherent in metals - electrical conductivity, a peculiar shine, high thermal conductivity. That is, a mixture of iron and carbon behaves like a metal. This material has a certain fragility. Most of its properties are determined by the complex structure of the crystal lattice.

This material melts at 1600 degrees Celsius. But there are several opinions on this matter; some researchers believe that its melting point lies in the range from 1200 to 1450, others determine that the upper level is 1300 °C.

Primary cementite

Metallurgists distinguish three types of this substance - primary, secondary, tertiary.

Iron-cementite diagram

Primary, obtained from the liquid during hardening of alloys that contain 5.5% carbon. The primary one has the shape of large plates.

Secondary

This element is obtained from austenite when the latter is cooled. On the diagram, this process can be seen in the Fe – C diagram. Cementite is presented in the form of a grid placed along the grain boundaries.

Tertiary

This type is derived from ferrite. It is shaped like needles.

There are other forms of cementite in metallurgy, for example, Stead's cementite, etc.

Other structural components in the iron-carbon system

Perlite

Perlite is a mechanical mixture that consists of ferrite and cementite. Ledeburite is a variable solution.

Perlite

At temperatures from 1130 to 723 ° C, its composition includes austenite and cementite. At lower temperatures it consists of austenite replacing ferrite.

Ledeburite in steels

Steels based on ledeburite are classified as alloyed. During crystallization, ledeburite is formed. On the iron-carbon phase diagram, this process is indicated at point E, which is located on the Fe – Fe3C line.

The use of elements such as chromium, tungsten and some others lead to the formation of alloys such as R6M5. This steel and its analogues are used in the manufacture of tools, for example, metal-cutting ones.

Nodal critical points of the iron-carbon system state diagram

On the iron-carbon diagram there are a number of points called critical points. Each point carries information about temperature, carbon content and a description of what exactly is happening in that place.

There are 14 of these critical points in total.

For example, A, says that at a temperature of 1539 ° C and at zero carbon content, pure iron melts. D indicates that at a temperature of 1260 Fe3c can melt.

The points are located at the intersection of lines placed on the diagram.

The meaning of the lines of the state diagram of the iron-carbon system

Each line located on the diagram also carries a semantic load. For example, the PQ line shows the precipitation of tertiary cementite from ferrite.

All interpretations of the meanings of points and lines are always available in the appendices to the carbon-iron phase diagram.

Source: https://stankiexpert.ru/spravochnik/materialovedenie/diagramma-zhelezo-uglerod.html

Iron-carbon alloys - steel and cast iron

The most widely used in modern mechanical engineering are iron-carbon alloys - steel and cast iron .

Steel is an alloy of iron and carbon; The carbon content in steel does not exceed 2%.

Steels include:

• technical hardware,
• structural and
• tool steel.

Cast iron is an alloy of iron and carbon in which the carbon content exceeds 2%. The average carbon content in cast iron is 2.5-3.5%.

In addition to iron and carbon, steels and cast iron contain impurities:

• silicon and manganese in tenths of a percent (0.15-0.60%)
• sulfur and phosphorus in hundredths of a percent (0.05-0.03%) of each element.

Steel

Steel with a carbon content of up to 0.7% is used for the manufacture of:

• sheets,
• ribbons,
• wires,
• rails,
• T-iron and angle iron,
• various shaped profiles,
• as well as for numerous parts in mechanical engineering : gears, axles, shafts, connecting rods, bolts, hammers, sledgehammers, etc.

Steel with a carbon content of over 0.7% is used for the manufacture of various cutting tools :

• incisors,
• drill,
• taps,
• beards,
• chisels, etc.

The properties of steel depend on the carbon content. The more carbon, the stronger and harder the steel.

Cast iron

Machine-building cast iron is used for the production of castings of all kinds of machine parts.

Based on their composition and structure, cast irons are divided into:

Malleable iron

Malleable cast iron is obtained by special processing of white cast iron. In white cast iron, all carbon is in a chemically bonded state with iron (Fe 3 C - cementite), which gives this cast iron greater hardness and brittleness and poor machinability.

White cast iron

In mechanical engineering, white cast iron is used to make castings that are annealed into the so-called malleable cast iron.

During annealing, cementite decomposes into iron and free carbon, and the castings acquire low hardness and good machinability.

Gray cast iron

The most widely used in technology is gray cast iron , in which most of the carbon is in a free state, in the form of graphite. This is facilitated by the high silicon content .

This cast iron has good casting qualities and is used for the production of iron castings. Parts made from this cast iron are obtained by casting into earthen or metal molds (frames, gears, cylinders, blocks, etc.).

Due to the presence of free carbon (graphite), gray cast iron has low hardness and is easy to cut.

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Source: http://www.Conatem.ru/tehnologiya_metallov/zhelezouglerodistye-splavy-stal-i-chugun.html

Iron alloys

Alloys are materials consisting of several chemical elements, at least one of which is a metal.

In metallurgy, iron and all its alloys are called ferrous metals.

All iron alloys are divided into steel and cast iron.

In its pure form, iron is too soft, so carbon is added to it to increase its strength. And depending on its content, iron alloys are divided into steel and cast iron. If the alloy contains more than 2.14% carbon, then such an alloy is called cast iron. And if less than 2.14%, then it is steel.

Cast iron

Typically, cast iron contains 2.5-4% carbon, 0.2-1.5% manganese, 1-4.5% silicon, phosphorus and sulfur impurities.

According to their structure, cast iron is divided into white and gray.

In white cast iron, most of the carbon is in the form of cementite (iron carbide Fe3C). Such cast irons are very hard and brittle. They are used for the manufacture of parts and structures that do not require further processing.

In gray cast irons, carbon is contained in the form of structural free graphite. When fractured, such cast iron has a gray color. It is well welded and machined with cutting tools.

A very long time ago, when they first learned how to produce cast iron, it was considered a production waste, since due to its fragility it was impossible to forge products from it. But later they learned to pour molten cast iron into molds and began to produce finished cast iron products: cannonballs, dishes, grates, etc.

Pig iron is produced in blast furnaces from iron ore. Iron ore contains iron oxides. During smelting, they are reduced by carbon. The result is molten metal with a high carbon content (cast iron) and slag. Since the density of cast iron is 2.5 times higher than the density of slag, it is easily separated from the slag.

Cast iron is produced for further conversion into steel and for foundry production in iron foundries.

Engine parts, cylinders, bushings, frames, grilles, hatches, brake pads, etc. are made from cast iron.

Classification of iron-carbon alloys

All iron-carbon alloys, in accordance with the iron-carbon diagram, are divided into technical iron (carbon content in the alloy less than 0.02%), steel (carbon content in the alloy from 0.02% to 2.14%) and cast iron (carbon content more than 2.14%)

Characteristics of steels

Steels are alloys of iron (Fe) with carbon (C), with the latter content not exceeding 2.14%. Steels are characterized by a fairly high density (7.7 - 7.9 g/cm3) and other physical quantities:*

• Specific heat capacity at 20°C: 462 J/(kg °C)
• Melting point: 1450—1520°C
• Specific heat of fusion: 84 kJ/kg (20 kcal/kg, 23 Wh/kg)
• Coefficient of linear thermal expansion at a temperature of about 20°C: 11.5·10-6 1/°С
• Thermal conductivity coefficient at a temperature of 100°C: 30 W/(m K)

*These specifications represent average values. The actual value of the properties depends on the carbon content and alloying elements in the steel. To accurately determine it, it is worth using steel and alloy graders.

In practice, steels with a carbon content of no more than 1.3% are used, because with its higher content, fragility increases.

Steel classification

Steels are characterized or classified according to many characteristics:

Classification by chemical composition

• carbon steels - classified depending on the carbon content in%:
  • low carbon (<0.25%C)
  • medium carbon (0.25-0.65%C)
  • high carbon (> 0.65%C)

• alloy steels - classified depending on the total content of alloying elements in%:
  • low alloy (<2.5%)
  • medium alloyed (2.5-10%)
  • highly alloyed (> 10%)

If the Fe content is less than 45%, then it is an alloy based on the element with the highest content. If the Fe content is more than 45%, then it is steel.

Classification by purpose

• structural – used for the manufacture of machine parts and mechanisms, carbon content 0.8%;
• with special properties: electrical, with special magnetic properties, heat-resistant, wear-resistant, etc.

classification - according to structure at equilibrium

Initially, this classification contained only 4 types of steels:

• hypoeutectoid
• eutectoid
• hypereutectoid
• ledeburite (having eutectic in the cast state)

Later additions were made:

Equilibrium state - the state of an alloy or steel after slow cooling, most often after annealing

Guillet classification - according to structure after normalization (heating and cooling in air)

• pearlite
• martensitic
• ferritic
• austenitic
• carbide

There can also be mixed classes: ferrite-pearlite, austenite-ferritic, etc.

Classification of steels by quality

A quantitative indicator of quality is the content of harmful impurities - sulfur and phosphorus:

• ordinary quality (S≤0.05, P≤0.04)
• quality steels (S, P ≤0.035)
• high quality (S, P ≤0.025)
• especially high quality (S≤0.015, P≤0.025)

Classification by smelting method

• in open hearth furnaces
• in oxygen converters
• in electric furnaces: electric arc, induction, etc.

Classification by degree of deoxidation

• boiling (kp)
• semi-calm (ps)
• calm (sp)

For expanded characteristics and properties (technological, physical and chemical composition) of some steel grades, see here.

Classification and marking of cast iron

Cast irons are alloys of iron and carbon containing more than 2.14% carbon. They contain the same impurities as steel, but in larger quantities.

Classification of cast irons

Depending on the state of carbon in cast iron, it is divided into the following types:

• white cast iron, in which all the carbon is bound in the form of carbide

Such cast iron can be hypoeutectic and hypereutectic, and they are separated by eutectic cast iron (4.31% C). The structure of hypoeutectic cast iron is pearlite, secondary cementite and ledeburite, while hypereutectic cast iron is primary cementite with ledeburite.

• graphitized cast iron, in which carbon is largely or completely free in the form of graphite, which determines the strength properties of the alloy. Such cast irons are divided into:
  • gray - lamellar or worm-shaped form of graphite (PPG)
  • high-strength - with spherical graphite (ChShG)
  • malleable - flake graphite (FG)
  • cast iron with vermicular graphite (CVG) - has intermediate properties between midrange and high-frequency. The shape of graphite is similar to midrange, but has thicker and shorter plates with rounded ends

Cast irons are also classified according to the base in which the graphite is located. The base can be pearlite, ferrite, ferrite-pearlite.

Marking of cast iron

Cast irons are marked with two letters and two numbers corresponding to the minimum value of tensile strength δv in MPa-10. Gray cast iron is designated by the letters “SCh” (GOST 1412-85), high-strength - “VCh” (GOST 7293-85), malleable - “KCH” (GOST 1215-85).

Labeling example

SCh10 - gray cast iron with tensile strength of 100 MPa; VC70 - high-strength cast iron with sigma temporary tensile strength of 700 MPa;

KCh35 is malleable cast iron with a tensile strength of approximately 350 MPa.

To work in friction units with lubrication, castings from antifriction cast iron AChS-1, AChS-6, AChV-2, AChK-2, etc. are used, which is deciphered as follows: ACh - antifriction cast iron: C - gray, B - high-strength, K - malleable. And the numbers indicate the serial number of the alloy according to GOST 1585-79.

Cast irons for special purposes

This group of cast irons includes heat-resistant (GOST 7769-82), heat-resistant and corrosion-resistant (GOST 11849-76) cast irons. This also includes non-magnetic, wear-resistant and anti-friction cast irons.

Heat-resistant are gray and high-strength cast irons alloyed with silicon (ChS5) and chromium (4Х28, 4Х32). Austenitic cast irons have high thermal and heat resistance: high-alloy nickel gray ChN15D7 and nodular graphite cast iron ChN15DZSh.

Heat-resistant cast irons include austenitic cast irons with spherical graphite ChN19KhZSh and ChN11G7Sh.

Cast irons alloyed with silicon (ferrosilides) - ChS13, ChS15, ChS17 and chromium - 4X22, 4X28, 4X32 are used as corrosion-resistant ones To increase the corrosion resistance of silicon cast irons, they are alloyed with molybdenum (4S15M4, 4S17MZ - antichlors). Nickel cast irons, for example, austenitic cast iron 4N15D7, have high corrosion resistance in alkalis.

as non-magnetic cast irons .

Wear-resistant cast irons include half-and-bleached cast irons. Wear-resistant half-cast irons include, for example, gray cast iron grade I4NH2, alloyed with nickel and chromium, as well as cast irons I4HNT, I4N1MSh (with nodular graphite).

Source: https://HeatTreatment.ru/klassifikaciya-zhelezouglerodistyh-splavov

Khakassia assumes all risks associated with the production of electrolytic manganese

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The company "CHEK-SU.VK", which caused a stir with the construction of a ferroalloy plant, has decided for now to implement its plans in the territory of neighboring Khakassia. Moreover, investors have already secured the support of the authorities of the republic and the governor himself, who considers the new project “strategically important for the entire country.”

The intentions of "CHEK-SU.VK" to create a production facility near Krasnoyarsk were not crowned with success: the local authorities and the population opposed it, and the businessmen were unable to resolve the issue through the courts.

The construction of a plant for the production of electrolytic metal manganese is planned near the village of Tuim, Shirinsky district of Khakassia, Governor Viktor Zimin said during his annual address.

“Russia does not have its own production capacity for this product; we are entirely dependent on imports, including from Ukraine. That is why our project is strategically important not only for Khakassia, but also for the entire country,” the head of the republic emphasized.

The government emphasizes that the Khakass project “CHEK-SU.VK” differs from the one that the company intended to implement near Krasnoyarsk.

At the Yenisei Ferroalloy Plant, businessmen wanted to install and launch five furnaces for smelting 235 thousand tons of manganese ferroalloys per year: 115 thousand tons of silicomanganese and 120 thousand tons of ferromanganese. The production volume was planned to be increased to 600 thousand tons per year.

The entire project, including ore mining, transportation and processing, was estimated at 22 billion rubles. and was sold with money from Vnesheconombank, which opened a credit line to CHEK-SU. Investors wanted to deliver raw materials from the Usinsky deposit in the Kemerovo region. Khakassia was considered a kind of transit zone, where, according to plans, roads were to appear, as well as a transshipment terminal in Tuim.

The village is located in the northern part of the republic, about 20 km from the village of Shira, which every summer attracts a lot of tourists from all over Siberia, including the Krasnoyarsk Territory, to the lakes. About 4.2 thousand people live in Tuim, and here a non-ferrous metals plant - in fact, a city-forming enterprise - has recently gone down in history.

“CHEK-SU.VK” intends to build a plant in Tuim for the production of electrolytic metal manganese “using electrolysis technology, widespread in the world,” the government of the republic assures.

“This will be an ordinary metallurgical plant with a closed water supply system, eliminating the discharge of wastewater, with the creation of a sanitary protection zone (1000 m) and sludge storage facilities, as well as using high-tech systems to ensure industrial and environmental safety,” explains the government of Khakassia. — Electrolytic manganese is an alloying additive that is widely used in the production of steel and special alloys. According to experts, the need for it on the part of Russian industry is high and will only continue to grow.”

The republican administration says that a new concept for the development of Tuim is currently being developed. "CHEK-SU.VK" is already preparing documents to undergo an environmental impact assessment (EIA).

Based on the results of the study, the company will begin developing design documentation for the construction of the plant - this will happen no earlier than 2016-2017, the government notes. Then you will have to go through the procedures of the Main State Expertise and the State Environmental Expertise.

The capacity of the plant in Tuim in terms of product output will be lower than that of the yet unfulfilled Federal Federal Law - 80 thousand tons of finished products per year.

With reference to representatives of CHEK-SU.VK, the government says that the enterprise will have about 1,000 jobs, and the same number of people will be employed in auxiliary production units. Thus, one factory can provide employment to half the village.

“The volume of investment, as well as the main parameters of the facility will be calculated in the project. If we talk about the payback of this project, then, as a rule, such enterprises begin to pay for themselves 10-15 years after reaching full capacity,” adds Acting Minister of Industry and Natural Resources of Khakassia Ekaterina Gerasimova.

The head of the republic, Viktor Zimin, who gave a positive assessment of the company’s intentions, believes that “production according to the existing hazard classification of industrial facilities is similar to open-pit coal mines” (hazard classes III-IV). For comparison: experts classified the EFZ as first class, that is, among the most dangerous industries.

“Of course, the final decision on construction will be made only after the environmental impact assessment is completed and the entire range of necessary measures has been completed,” the governor said.

The plant in Khakassia initially existed as part of a large investment project for the development of the Usinsk field, but its construction was planned after the launch of the Federal Economic Zone, they say in the company “CHEK-SU.VK”.

However, the issue of creating production near Krasnoyarsk is largely up in the air. Although the court found the refusal of the Yemelyanovsky district administration to issue a construction permit illegal, the company still failed to achieve an acceptable measure to restore its rights.

The plaintiffs wanted officials to be required to issue a permit, but the court did not do so.

The case went through several instances - to the Supreme Court of the Russian Federation, which refused to consider the complaint from CHEK-SU. However, this decision is not final for CHEK-SU, the company emphasized.

“The decision to build a plant depends on one more document - this is a list of instructions from the President of the Russian Federation dated June 28, 2013, which the administration of the Krasnoyarsk Territory simply ignores and which is under the control of the presidential administration,” says a representative of CHEK- SU.VK" Alexander Sysolyatin. “Should we stop carrying out the president’s orders?”

He noted that now the company’s plans depend on “how the list of president’s instructions will be carried out”: “CHEK-SU” “wants” to implement its project in Krasnoyarsk, but “can’t yet.”

According to a company representative, the intentions of the regional authorities to move the oil depot from the city to the Krastyazhmash area have nothing to do with the EFZ site:

“There is indeed a facility not far from our site where petroleum products were either stored or produced. This is the object, in my opinion, that they want to use,” Sysolyatin suggested.

Road in Khakassia

"CHEK-SU" has already built part of the road in Khakassia to transport concentrate from the Usinsk deposit.

He explained that the construction of an electrolytic manganese plant in Khakassia was not a spontaneous decision, and it was planned at the very beginning. They wanted to implement the project after the completion of work at the EFZ, but “forced” because of the difficulties that arose, “it came ahead of the project for the production of manganese ferroalloys.”

“Money cannot hang around forever - it must be given back at some point,” Sysolyatin noted. “Moreover, we borrowed funds from Vnesheconombank and must repay them.”

At the moment, about 9 billion rubles have been invested in the implementation of the entire project for the development and processing of ores from the Usinsk deposit, he confirmed. At the same time, Sysolyatin said that CHEK-SU has already applied “to Vnesheconombank with a loan application for the implementation of a project for the construction of a plant for the production of electrolytic manganese” in Khakassia, dela.ru reports.

Among the arguments that led to the powerful opposition of Krasnoyarsk against the ferroalloy plant was the environmental approach of the CHEK-SU company to the organization of production.

According to one of the experts, during a study of the environmental approaches of the Chek-SU company, it turned out that in Russian conditions, it is easier for large businesses whose production facilities have a negative impact on the environment to pay a penny fine than to invest multimillion-dollar funds in environmental projects that preserve life and health of their fellow citizens.

The silence of the heads of Krasnoyarsk polluting companies regarding the environmental dangers of manganese production showed that they are aware of the negative consequences of such production.

For example, the managers of the Krasnoyarsk aluminum smelter are unlikely to have forgotten how, during the accident at the Sayano-Shushenskaya hydroelectric power station, Krasnoyarsk was plunged into darkness, because in order to preserve electrode production, waste was removed directly? At the same time, the management and shareholders of KrAZ were not punished even within the framework of existing legislation.

What will happen to Krasnoyarsk and its surroundings in the event of an accident at a manganese plant? Will someone really stop production and sacrifice key equipment?

The CHEK-SU company agreed to bear social responsibility to Krasnoyarsk residents. Then why didn’t she want to build production workshops and rotational camps next to the deposit, in an open field - there is no need to transport ore anywhere, and there is no need to worry about the environment during transportation either! The answer is simple - money, big money.

Let us remind you that the ex-governor of the Krasnoyarsk Territory and his team supported Krasnoyarsk residents in the fight for their health. The authorities of Khakassia easily agreed, taking over (the residents of the republic) a strategic object important for the entire country.

Reference

Ferroalloys are alloys of iron with other metals. In addition, ferroalloys include metals and alloys containing iron only as an impurity. Application of ferroalloys: as alloying elements and deoxidizing agents for steel in order to impart certain properties to the metal; to bind harmful impurities in the alloy; for the production of other ferroalloys.

Properties of ferroalloys: the melting point of ferroalloys is lower than the melting point of most metals, which means that ferroalloys dissolve faster during melting: steel is more easily absorbed by the melt, the leading element practically does not burn. Preparation of ferroalloys: in electric furnaces during heat treatment of iron-containing ores or concentrates. The cost of ferroalloys is lower than pure metal, which is due to the simple and fast process of processing raw materials.

Related news:

Construction of an electrolytic manganese plant in Khakassia is a resolved issue

Dirty and crumpled sheets: the administration of the Shirinsky district responded to opponents of the plant

"Chek-Su.VK" wants two manganese plants - near Krasnoyarsk and in Khakassia

Ferroalloy plant in Khakassia - here you go, God, it’s no good for us

Review of events from June 2 to June 9: parabola of elements and fatal mistakes

The probability of building a ferroalloy plant near Krasnoyarsk has decreased to less than 1%

Source: http://www.19rus.info/index.php/ekonomika-i-finansy/item/24077-ferrosplavnyj-zavod-v-khakasii?template=ia19012020&is_preview=on

Iron-carbon diagram. State diagram of the iron-carbon system

It is difficult to imagine modern construction, technology, mechanical engineering and other important industries without the use of the main metal alloys of steel and cast iron. Their production exceeds all others by tens of times.

If we consider steel and cast iron from the point of view of such a science as metallurgy, then the central figure is the state diagram of iron-carbon alloys, which allows us to obtain detailed ideas about the composition and structural transformations in these materials. And also get acquainted with their phase composition.

History of discovery

For the first time, the great metallurgist and inventor Dmitry Konstantinovich Chernov (1868) pointed out that there are certain (special) points in alloys (steels and cast irons). It was he who made an important discovery about polymorphic transformations and is one of the creators of the iron-carbon phase diagram. According to Chernov, the position of these points on the diagram is directly dependent on the percentage of carbon content.

And what is most interesting is that it is from the moment of this discovery that the science of metallography begins its life.

The diagram of iron-carbon alloys is the result of the painstaking work of scientists from several countries around the world. All letter designations of the main points and phases in the diagram are international.

A graphical representation of the processes occurring in an alloy with changes in temperature, concentration of substances, and pressure is called a phase diagram. It allows you to visually and volumetrically see all the transformations occurring in alloys.

Elements of the iron-carbon diagram

Brief information about each of these elements.

Iron is a silvery-gray metal. Specific gravity - 7.86 g/cm3. It has a melting point of 1539° C.

When iron and other metals interact, compounds called substitution solutions are formed. If with non-metals, for example with carbon or hydrogen, then - interstitial solutions.

Iron has the ability, being initially solid, to exist in several states, which in metallurgy are usually called “alpha” and “gamma”. This quality is called polymorphism. More on this later in the article.

Carbon is a non-metal. If it acts as graphite, then the melting point is 3500° C. If it is like diamond, it is 5000° C. The density of carbon is 2.5 g/cm3. It also has polymorphic properties.

In iron-carbon alloys, this element forms a solid solution that contains a ferrum called cementite (Fe3C). Also forms graphite in cast irons.

Iron-carbon alloy diagram

As a result of the interaction of the components of the diagram with each other, cementite is obtained - a chemical compound.

As a rule, when studying a diagram by metallurgical students, all stable connections are considered as components, and the graphic image itself is examined in parts.

Also in class, a cooling curve is plotted using the iron-carbon diagram: the percentage of carbon is selected, and then it is necessary to determine which phase corresponds to which temperature on the diagram.

To do this, in addition to the diagram itself, it is necessary to draw a coordinate system (temperature-time). And starting from the maximum degrees, move gradually downward, depicting the curve and areas of transition from one phase to another. In this case, it is necessary to name them and indicate the type of crystal lattice.

Next, let's take a closer look at the graphical representation of the iron-carbon phase diagram itself.

Firstly, it has two forms (parts):

• iron cementite;
• iron-graphite.

Secondly, alloys in which the main “actors” are ferrum and carbon are conventionally divided into:

If the carbon in the alloy is less than or equal to 2.14% (point E on the diagram), then it is steel, if more than 2.14% it is cast iron. For this reason, the diagram is divided into two phases.

Polymorphic transformations

More details about each phase are given below in the article. In short, the main transformations occur at special temperatures.

The state of iron is designated as α-ferrum (at a temperature less than 911 ° C). The crystal lattice is a volumetric face-centered cube. Or OCC. The distance between the atoms of such a lattice is quite high.

Iron acquires the gamma modification, that is, it is designated as γ-ferrum (911-1392° C). The crystal lattice is a face-centered cube (FCC). In this lattice the distance between atoms is lower than in bcc.

When α-ferrum transforms into γ-ferrum, the volume of the substance becomes smaller. The reason for this is the crystal lattice - its appearance. Because the fcc lattice has a more ordered state of atoms than the bcc lattice.

If the transition is carried out in the opposite direction - from γ-ferrum to α-ferrum, then the volume of the alloy increases.

When the temperature reaches 1392° C (but less than the melting point of iron 1539° C), then α-ferrum turns into δ-ferrum, but this is not its new form, but only a variety. In addition, δ-ferrum is an unstable structure.

Properties of commercially pure iron

Magnetic properties of iron at different temperatures:

• less than 768° C – ferromagnetic;
• more than 768° C – paramagnetic.

And the temperature point of 768° C is called the magnetic transformation point, or the Curie point.

Properties of technically pure iron:

• hardness – 80 HB;
• temporary resistance - 250 MPa;
• yield strength – 120 MPa;
• relative elongation 50%;
• relative narrowing – 80%;
• high modulus of elasticity.

Iron carbide

Graphical view of the constituent part of the iron-carbon diagram: Fe3C. The substance is called iron carbide, or cementite. It is characterized by:

1. carbon 6.67%.
2. Specific gravity - 7.82%.
3. The crystal lattice has a rhombic shape, consisting of octahedra.
4. Melting occurs at a temperature of ≈1260° C.
5. Low ferromagnetic properties at low temperatures.
6. Hardness – 800 HB.
7. Plasticity is practically zero.
8. Iron carbide forms substitutional solid solutions in which carbon atoms are replaced by non-metal atoms (nitrogen), and iron atoms by metals (chromium, tungsten, manganese). This solid composition is called alloyed.

As noted above, cementite is an unstable phase, and graphite is stable. Since the first substance is an unstable compound, decomposing under certain temperature conditions.

The iron-carbon diagram has the following states:

• liquid phase;
• ferrite;
• austenite;
• cementite;
• graphite;
• perlite;
• ledeburite.

Let's look at each of them in detail.

Liquid phase

Ferrum in the liquid state dissolves carbon well. This is regardless of what proportion they are in percentage terms. As a result, a homogeneous liquid mass is formed.

Austenite

Austenite is a solid solution of carbon (up to 2%) and alloying elements in α-iron. Its hardness is 2-2.5 times greater than that of ferrite, with high ductility. This structure is obtained by thermal and chemical-thermal treatment.

Ledeburite

Ledeburite is one of the main structural components of iron-carbon alloys. At the time of formation it consists of cementite and austenite, and after cooling - of cementite and pearlite. Contains 4.3% carbon and is highly hard and brittle.

Types and characteristics of iron alloys

Iron is considered the most popular material. It is used in all industries. People have been familiar with this metal since ancient times. When blacksmiths learned to obtain pure material, it surpassed the alloys known at that time and forced them out of production. Iron alloys appeared as a result of people's attempts to change the characteristics of this metal.

Composition and properties

The structure and properties of iron determine its popularity in various industries. The composition is a basic material with admixtures of other substances. The amount of additional metals does not exceed 0.8%. The main parameters include:

1. Melting point - 1539 degrees Celsius.
2. Brinell hardness - 350–450 MN/sq. m.
3. Specific gravity - 55.8.
4. Density - 7.409 g/cm3.
5. Thermal conductivity - 74.04 W/(m K) (at room temperature).
6. Electrical conductivity - 9.7·10-8 ohm·m.

We must not forget that iron is considered one of the most important elements in the human body. However, it is extremely difficult to absorb from food. The daily norm that a man should consume is 10 mg. Women should consume 20 mg of this substance for the body to function normally.

Areas of application

This material is used in various industries:

1. Mixtures and homogeneous metal are used in mechanical engineering. Internal parts, housings, and moving mechanisms are made from them.
2. Shipbuilding, aircraft manufacturing, rocketry.
3. Construction - production of fasteners, consumables.
4. Instrument making - manufacturing electronics for the home.
5. Radioelectronics - creation of elements for electrical appliances.
6. Medicine, machine tool building, chemical industry.
7. Making weapons.

If a homogeneous material is not suitable for something, compounds based on it, the characteristics of which differ significantly, will do.

Types of iron-based alloys

An iron alloy is a compound that consists of a base metal and additional impurities. Compounds based on this material are called ferrous metals. These include:

1. Steel is a combination of carbon with other elements. Carbon in the alloy can contain up to 2.14%. There are structural carbon, construction, special and alloy steels.
2. Cast iron is a mixture that is very popular. Compounds can contain up to 3.5% carbon. Additionally, the mixture contains manganese, phosphorus, and sulfur.
3. Perlite is an iron-based mixture. Contains no more than 0.8% carbon.
4. Ferrite is called a pure material. This is due to the low content of carbon and third-party impurities (about 0.04%).
5. Cementite is a chemical compound of iron and carbon.
6. Austenite is a compound with a carbon content of up to 2.14%. Additionally, it contains foreign impurities.

Composition and structure of alloys

Due to the large number of iron-based compounds, markings have been developed that can be used to separate steels with a high carbon content from less carbon ones, determine the presence of the main alloying elements in the composition of the material, and their quantity. Depending on the number of additional elements, the properties of the connections change. These include boron, vanadium, molybdenum, manganese, titanium, carbon, chromium, nickel, silicon, tungsten.

The characteristics of mixtures depend on their structure and composition. This changes strength, ductility, melting point, density, electrical conductivity and other parameters. For example, the structure of cast iron determines its fragility under impacts and heavy physical stress.

Properties and marking of alloys

Regarding labeling, the first numbers that appear on the label indicate the percentage of carbon in the composition. Next come the capital letters of the main alloying elements. Additional letters may begin the marking. They indicate the purpose of the alloy.

Plasticity and toughness will decrease as the amount of carbon in the alloy increases. Other properties of metals are influenced by the main alloying elements.

Production and processing of iron-based alloys

To understand how popular iron-based compounds are produced, we need to briefly talk about the technologies for producing cast iron and steel. You can get steel in several ways:

1. Direct technology. Iron ore pellets are blown through with a mixture of carbon monoxide, oxygen and ammonia. The procedure is carried out in a shaft furnace heated to 1000 degrees.
2. Martin's method. Solid cast iron is melted using open hearth furnaces. Before completing the procedure, the material is saturated with impurities.
3. Electric melting method. With its help, high-quality material is obtained. Processing is carried out in closed ovens at temperatures up to 2200 degrees.
4. Oxygen-converter method. The cast iron located in the furnace is blown with a mixture of oxygen and air, which speeds up the annealing process.

Iron production:

1. Ore preparation. It is crushed to a fine fraction.
2. Grinding of coke coal.
3. Flux crushing.
4. into the oven.

Blast furnaces are used to make cast iron.

In addition to the production processes of the mixtures, they are subjected to additional processing. These are annealing, normalizing, hardening and tempering. Characteristics are improving.

Iron alloys are used in various industries.
They have different characteristics, but do not lose the parameters of the base metal included in their composition. Steel metallurgy 1 - iron, solutions, ferrite, austenite, cementite and pearlite

Types and characteristics of iron alloys Link to main publication

Source: https://metalloy.ru/splavy/zheleza