How does carbon content affect the properties of steel?

Pros, cons and features of xv5 steel for knives - Website about

03.01.2019

It is difficult to imagine a hunter, fisherman or tourist without a knife. The blade helps out in the most unexpected situations. To choose a good product, you need to familiarize yourself in advance with the properties of the material from which the blade is made. One of the best alloys is considered to be xv5 steel for knives, the pros and cons of which must be taken into account by every hunter and traveler.

Chemical composition of the material

In metallurgical reference books, chrome tungsten steel xv5, due to its high hardness, received the additional name Almazka. This alloy is considered the most suitable for making knives. Diamond steel contains several chemical elements that affect its properties:

1. Chromium (0.4-0.7%) – compacts the crystal lattice. Used for the production of anti-corrosion material (stainless steel). If its concentration does not reach 10.5%, the hardenability of steel improves.
2. Carbon (1.25-1.45%) - has a direct effect on the hardness of the metal. The HRC of diamond steel is 63-68 Rockwell units.
3. Tungsten (4.5-5%) – increases the strength of steel when heated to 250 degrees or more.

The production of the xv5 alloy began in the 19th century. In the USSR, this metal was used to create diamond cuts. A special technological process was developed for its production.

First, a cast iron mold is made into which the hot mass is poured. It is then cooled with ice water.

As a result of the operations performed, the metal becomes very durable, which makes it possible to manufacture high-quality products from it.

Advantages and disadvantages

Diamond steel knives are considered quite hard. The blade does not require frequent sharpening. The NKVD knife made of diamond steel was capable of cutting soft metals. This tool could even remove chips. Chrome, which is part of knives made of steel xv5, protects the product from corrosion. However, due to the insufficient concentration of this substance, the metal cannot be called completely stainless.

Any knife made of xv5 diamond steel differs from others in a number of positive qualities:

• long service life;
• attractive appearance;
• sharp sharpening;
• practically does not dull;
• the blade is highly durable;
• Capable of cutting hard materials.

Diamond knives also have disadvantages:

• high cost (5000-15000 rubles);
• steel is difficult to sharpen in the field;
• fragility, the blade does not tolerate lateral loads.

A knife made of diamond steel xv5 should not be kept in a humid environment for a long time. The blade may begin to rust.

Scope of use of diamond steel

Hard blades made from this alloy are used for various purposes. Since xv5 steel has increased hardness, it is used in the industrial sector for metal processing.

Diamond steel is used to make magnificent, very durable knives that are used by hunters and travelers. With a Almazka blade you can easily skin a carcass, cut a skin, or open a tin can. Almazka is not suitable for use in the kitchen.

This metal does not tolerate high humidity; the blade may begin to corrode.

Among other things, souvenir and gift knives are produced from xv5 steel. The handle of such products, made of valuable wood, is often decorated with special engraving.

Spontaneous, intricate patterns sometimes appear on the blade, which give the blade even greater aesthetic value.

Such decoration is made possible due to the uneven distribution of metal and carbon in the alloy.

What to look for when choosing

The design of any knife includes two parts: the handle and the blade. To prevent your hand from getting tired while working, the product should have a comfortable handle. Its material affects the most important characteristics of the knife:

• maneuverability;
• strength;
• comfort;
• balancing;
• resistance to pollution.

It is important to choose a knife with a handle made of practical material. The handle made from birch bark is especially valued. It has a number of positive qualities:

1. Low thermal conductivity. Can work at sub-zero temperatures.
2. Moisture resistance. Birch bark contains tar, which repels water. In addition, it gives the pen disinfectant properties.
3. Birch bark never rots, which ensures long-term operation.
4. Increased electrical insulation. Will protect your hand in case of accidental contact of the knife with a live object.

When choosing a folding knife, you need to pay special attention to its mechanism. The product should be easy to open with one hand and close freely without injuring your fingers. Today, several types of locks are used, which have their advantages and disadvantages:

1. Liner Lock is the most common mechanism. The heel of the blade is fixed due to a certain position of the spring. The blade is retracted after pressing the bar. This is inconvenient for lefties.
2. Axis Lock – This system is easy to use for both left and right handed people. The working position of the blade is fixed with a pin. A small movement is enough to close or open the knife.
3. Compression Lock – this design has appeared recently, reminiscent of the Liner lock. It features a reliable mechanism designed for left and right hands. A special safety device prevents the knife from folding unexpectedly.

The quality of a knife largely depends on its manufacturer. In our country, products made in several regions are very popular:

1. Kizlyar - Dagestan is famous for the production of cold blades. Today, the company of the same name produces universal and folding knives of various designs.
2. Vorsma is a company operating in the Nizhny Novgorod region that manufactures hunting knives equipped with special pommels, mounted handles, and cast forges. The best blades are considered to be Zavyalov's blades, as well as folding knives made by Marychev.
3. Zlatoust - in this small Ural town, damask steel began to be smelted back in the 19th century. Today, products from the AIR company are very popular. It produces hunting and camping knives made of durable steel.

On the domestic market you can find a large assortment of Chinese copies of knives from Almazka. They have nothing to do with real blades made of this alloy.

This is a poorly made fake that does not have the qualities of diamond steel. To protect yourself from purchasing a low-quality blade, it is better to purchase such products only from trusted manufacturers.

It is important to understand that a knife made of xv5 steel cannot be cheap.

Rules of use and care

After use, the blade is washed well and wiped thoroughly. The blade is then coated with a thin layer of oil.

If the knife is used in conditions of high humidity, it is better to carry out this procedure several times.

In the field, it is sometimes necessary to wash the knife with sea water; in such cases, it is necessary to rinse it again in fresh water, wipe it dry and lubricate it with any animal fat.

Most knife owners try to use special cases for storage. There is no need to do this. The sheath quickly accumulates moisture. They cause corrosion.

To protect the product from excess moisture, you need to store it wrapped in an oily cloth. To prevent the wooden handle from drying out and maintaining its water-repellent properties, it must be regularly lubricated with oil.

Copper finials can be rubbed with ordinary polishes.

Knives made of diamond steel xv5 should be used only as a cutting tool. When traveling, the back of the handle can be turned into a hammer, and the blade can be used to open canned food. When working with a Almazka knife, you should avoid chopping blows. For example, when cutting a carcass carelessly, a blow to a large bone can cause damage to the cutting edge of the knife.

Sometimes pitting corrosion, so-called “freckles,” appears on the blade. It can be easily removed with a stationery eraser. You can also use a fine abrasive car polish.

 If the blade is severely damaged by corrosion, to correct this defect it is necessary to remove the factory surface treatment of the blade. For this purpose, special abrasive sponges are used, and sometimes fine-grained sandpaper is used. The cleaned blade is polished again to a shine.

There should be no scratches or marks left on the surface that could cause a new source of corrosion.

You can only wipe with a dry cloth.
Rust can be removed with a stationery eraser.

What determines the hardness of xv5 steel for knives, the pros and cons of the alloy Link to the main publication

Source: https://narobraz.ru/remont-i-stroitelstvo/plyusy-minusy-i-osobennosti-stali-hv5-dlya-nozhej.html

Materials Science

Carbon steels are the main ones. Their properties are determined by the amount of carbon and the content of impurities that interact with iron and carbon.

Carbon influence

The effect of carbon on the properties of steels is shown in Fig. 10.1

As the carbon content in the steel structure increases, the amount of cementite increases, while the proportion of ferrite decreases. Changing the ratio between the components leads to a decrease in ductility, as well as an increase in strength and hardness. Strength increases up to a carbon content of about 1%, and then it decreases as a coarse network of secondary cementite is formed.

Carbon affects viscous properties. Increasing the carbon content increases the threshold of cold brittleness and reduces toughness.

Electrical resistance and coercive force increase, magnetic permeability and magnetic induction density decrease.

Carbon also affects technological properties. An increase in carbon content worsens the casting properties of steel (steels with a carbon content of up to 0.4% are used), workability by pressure and cutting, and weldability. It should be taken into account that steels with low carbon content are also difficult to cut.

Impact of impurities

Steels always contain impurities, which are divided into four groups.

1. Permanent impurities : silicon, manganese, sulfur, phosphorus.

Manganese and silicon are introduced during the steelmaking process for deoxidation; they are technological impurities.

manganese does not exceed 0.50.8%. Manganese increases strength without reducing ductility, and sharply reduces the red brittleness of steel caused by the influence of sulfur. It helps reduce the content of iron sulfide FeS , as it forms a compound with sulfur, manganese sulfide MnS . Manganese sulfide particles are located in the form of separate inclusions, which are deformed and appear elongated along the rolling direction.

silicon does not exceed 0.350.4%. Silicon, by degassing the metal, increases the density of the ingot. Silicon dissolves in ferrite and increases the strength of steel, especially the yield strength increases. But there is a slight decrease in ductility, which reduces the ability of steel to draw

phosphorus in steel 0.0250.045%. Phosphorus, dissolving in ferrite, distorts the crystal lattice and increases the tensile strength and yield strength, but reduces ductility and toughness.

Being located near the grains, it increases the temperature of transition to a brittle state, causes cold brittleness, reduces the work of crack propagation. An increase in phosphorus content by every 0.01% increases the threshold of cold brittleness by 2025 o C.

Phosphorus has a tendency to segregate, so in the center of the ingot, individual areas have a sharply reduced viscosity.

For some steels, it is possible to increase the phosphorus content to 0.100.15% to improve machinability.

S – ductility, weldability and corrosion resistance decreases. P– distorts the crystal lattice.

sulfur in steels is 0.0250.06%. Sulfur is a harmful impurity that gets into steel from cast iron.

When interacting with iron, it forms a chemical compound - sulfur sulfide FeS , which, in turn, forms a low-melting eutectic with iron with a melting point of 988 o C.

When heated for rolling or forging, the eutectic melts and the bonds between grains are broken. During deformation, tears and cracks appear at the locations of the eutectic, and the workpiece is destroyed - the phenomenon of red brittleness .

Red brittleness – increased brittleness at high temperatures

3. Special impurities - specially introduced into steel to obtain specified properties. Impurities are called alloying elements, and steels are called alloyed steels.

Purpose of alloying elements

The main alloying element is chromium (0.81.2)%. It increases hardenability and helps to obtain high and uniform hardness of steel. The threshold for cold brittleness of chromium steels is (0-100)oC.

Additional alloying elements.

Boron - 0.003%. Increases hardenability and also increases the threshold of cold brittleness (+20-60 o C. )

Manganese - increases hardenability, but promotes grain growth, and increases the cold brittleness threshold to (+40-60) o C.

Titanium (~0.1%) is introduced to refine the grain in chromium-manganese steel.

The introduction of molybdenum (0.150.46%) lowers the cold brittleness threshold to –20-120 o C. Molybdenum increases the static, dynamic and fatigue strength of steel and eliminates the tendency to internal oxidation. In addition, molybdenum reduces the tendency of steels containing nickel to become temper brittle.

Vanadium in an amount of (0.10.3)% in chromium steels refines the grain and increases strength and toughness.

The introduction of nickel into chromium steels significantly increases strength and hardenability, lowers the threshold of cold brittleness, but at the same time increases the tendency to temper brittleness (this disadvantage is compensated by the introduction of molybdenum into the steel). Chromium-nickel steels have the best range of properties. However, nickel is scarce and the use of such steels is limited.

A significant amount of nickel can be replaced with copper, this does not lead to a decrease in viscosity.

When chromium-manganese steels are alloyed with silicon, steels are obtained - chromansil (20KhGS, 30KhGSA) . Steels have a good combination of strength and toughness, and are well welded, stamped and machined. Silicon increases impact strength and temperature reserve viscosity.

The addition of lead and calcium improves machinability. The use of hardening heat treatment improves the complex of mechanical properties.

Alloying elements dissolve in the main phases of iron-carbon alloys (ferrite, austenite, cementite), or form special carbides.

The dissolution of alloying elements occurs as a result of the replacement of iron atoms with atoms of these elements. These atoms create stresses in the lattice, which cause a change in its period.

Changing the dimensions of the lattice causes a change in the properties of ferrite - strength increases, ductility decreases. Chromium, molybdenum and tungsten strengthen less than nickel, silicon and manganese. Molybdenum and tungsten, as well as silicon and manganese in certain quantities, reduce viscosity.

In steels, carbides are formed by metals located in the periodic table to the left of iron (chromium, vanadium, titanium), which have a less complete d - electron band.

In the process of carbide formation, carbon donates its valence electrons to fill the d -electron band of the metal atom, while in the metal the valence electrons form a metallic bond, which determines the metallic properties of carbides.

When the ratio of the atomic radii of carbon and metal is more than 0.59, typical chemical compounds are formed: Fe 3 C , Mn 3 C , Cr 23 C 6 , Cr 7 C 3 , Fe 3 W 3 C - which have a complex crystal lattice and, when heated, dissolve in austenite.

When the ratio of the atomic radii of carbon and metal is less than 0.59, interstitial phases are formed: Mo 2 C , WC , VC , TiC , TaC , W 2 C - which have a simple crystal lattice and are difficult to dissolve in austenite.

All carbides have high hardness and melting point.

4. Random impurities.

Source: https://moodle.kstu.ru/mod/book/view.php?id=27869

How does industry affect the environment and which enterprises harm the environment?

Human impact on nature is rapidly increasing and has become global. Industrial production facilities are powerful sources of environmental pollution. Damage is caused to the animal and natural worlds, air, water, soil, and human health.

Impact of enterprises on the environment

Industrial enterprises of metallurgy, mechanical engineering, energy and oil refining industries have a negative impact on the environment.

Metallurgy

Metallurgical enterprises belong to the category of the most environmentally “dirty”. Among all environmental pollution, they account for almost 35%. The greatest harm is caused by man-made emissions from operating workshops. Stored waste and the discharge of waste into natural water bodies have a negative impact. Emissions from metallurgical production into the natural environment cause:

• accumulation of heavy metals in soils adjacent to enterprises;
• alkalization and acidification of fertile lands;
• destruction of vegetation;
• geochemical anomalies;
• soil erosion;
• pollution of fresh water sources;
• formation of man-made wastelands around factories;
• deterioration of public health.

Did you know that metallurgical plants take a quarter of public water and pollute surface waters?

Not really

Depending on the stage of the metallurgical cycle, enterprises emit dust, slag, sludge, and gases. Main pollutants:

• mercury;
• benzopyrene;
• hydrogen sulfide;
• carbon dioxide;
• fluorides;
• Nitric oxide;
• sulfur oxide;
• heavy metals (chrome, lead, molybdenum, copper, nickel, cobalt);
• compounds of manganese, vanadium;
• graphite dust.

Sulfur dioxide contributes to acid rain.

Anthropogenic and natural factors of air pollution in cities

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Negative consequences resulting from contamination of the Earth's soil layer

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Types of environmental pollution affecting human health

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What measures can be used to protect soil from pollution?

Further

Energy industry

Energy enterprises (thermal power plants, hydroelectric power plants, nuclear power plants) account for 27% of the total level of environmental pollution.

Thermal power plants (TPP) have the greatest negative impact. This:

• toxic and radiation contamination of the environment;
• thermal pollution of the cooling pond.

Pollutants from thermal power plants include:

• fine solid fractions of ash;
• nitrogen oxides;
• sulfur oxides.

Natural and anthropogenic sources of radioactive contamination

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Impact of old and new nuclear power plants on the environment

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Hydroelectric power plants built on rivers cause problems associated with reservoirs:

• flooding of large areas;
• accumulation of large amounts of pollution;
• change in the microclimate of the region;
• development of eutrophication processes;
• disturbance of natural spawning grounds;
• flooding of agricultural land;
• change in groundwater level.

Man in relation to nature: destroyer or preserver?

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Chemical pollution of the atmosphere, hydrosphere, soil resources

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Environmental pollution of hydroelectric power stations is considered to be the presence of a flow of electromagnetic radiation that occurs during the transmission of electricity by high-voltage lines over long distances. Radiation affects both animals and people.

Before the Chernobyl accident, nuclear power plants were considered the most environmentally friendly. Given the possible contamination of the environment with radiation, this will be the most dangerous type of production. The biggest problem is the disposal of radioactive waste . When they are neutralized, the radiation effect is not destroyed, but if the repository is disturbed, it can lead to contamination of the natural environment.

Proper disposal of hazardous waste: what you need to know

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Recycling waste and garbage is the main direction of ecology in the fight for a clean planet

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We recycle waste and get energy resources. Effective waste recycling methods

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Mechanical engineering

The mechanical engineering complex is involved in the production of a variety of products, the production of which requires the use of raw materials and technological resources that can cause environmental problems. Main negative manifestations:

• air pollution due to emissions from enterprises;
• soil contamination with harmful waste;
• negative impact on flora, fauna and humans;
• pollution of natural water bodies with wastewater.

Technogenic environmental pollution

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Mechanical engineering in Russia and its harmful production affecting the environment

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Major environmental disasters in Russia

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Harmful components of emissions from engineering enterprises:

• carbon monoxide;
• sulfur dioxide;
• acids;
• chromium;
• phosphorus;
• cadmium;
• heavy metal salts;
• mercury;
• lead;
• cyanides, chlorides, sulfates.

Heavy metals are the most dangerous elements that can pollute the soil

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Is it possible to solve modern environmental problems on a global scale?

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Slag, sawdust, ash, and shavings get into the soil. Working solutions of electrolytes from electroplating production are discharged into rivers.

Oil refining

Petroleum refining is used to produce different types of fuels and chemicals. All stages of the technological process of oil production and refining pose a danger to the environment. Possible negative manifestations:

• rock subsidence;
• earthquakes;
• groundwater and surface water pollution;
• changing of the climate;
• soil pollution with changes in its properties.

Hazardous components released during oil refining:

• hydrocarbons;
• Nitric oxide;
• sulfur compounds;
• ammonia;
• resins;
• acids.

Oil fields of the world: reserves and production volumes

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Shale oil production - impact on the ecology of the planet

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The largest coal deposits in Russia

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Possible measures to reduce the environmental impact of production

Main events:

1. Changing the sectoral structure of industrial enterprises , including the creation of low-waste industries.
2. Improvement of technological equipment.
3. Recycling of waste.
4. Introduction of technologies aimed at preserving natural resources.
5. Creation of new types of products with a longer service life and the ability to be recycled.
6. Application of modern cleaning technologies.
7. Integrated use of raw materials and waste.
8. In the energy industry - the development of new non-traditional environmentally friendly types of energy.
9. Optimization of thermal and electrical energy consumption.

Source: https://greenologia.ru/eko-problemy/proizvodstvo.html

Carbon, sulfur and phosphorus analysis

Steel is the most common alloy of iron and carbon, which includes a number of inevitable impurities (Mn, Si, S, P, O, N, H, etc.). All of them affect the properties of steel, so chemical analysis is a mandatory element of the quality system at the enterprise.

• Carbon analysis. Carbon is the main component of steel, which is presented in different forms and determines its grade and basic properties.
• Analysis for sulfur and phosphorus. Sulfur and phosphorus are difficult-to-remove elements that come mainly from cast iron during steel smelting. They are considered harmful impurities, as they deteriorate the quality of steel. The maximum permissible sulfur content is no more than 0.06%, and phosphorus - 0.05%. During metal smelting, efforts are made to carry out desulfurization and dephosphorization measures to reduce the influence of these elements.

The influence of carbon, sulfur and phosphorus on steel quality

The determination of carbon, sulfur and phosphorus in steel is of primary importance for metallurgists, foundries and machine builders. This allows you to obtain high-quality products and eliminate irreparable defects. State standards regulate the content of impurities in steel and methods for determining their content.

Carbon in steel

Carbon is a polymorphic non-metallic element that can dissolve in iron in liquid and solid states to form solid solutions - ferrite and austenite. In addition, it creates a chemical compound with iron - cementite (Fe3C), and can be presented in high-carbon steels in the form of graphite.

Depending on the carbon content, steels are classified into:

• low carbon (up to 0.3% C);
• medium carbon (0.3-0.6% C);
• high-carbon (more than 0.6% C).

carbon affects the structure of steel, the quantity and ratio of phases, and therefore determines the hardness and ductility of the metal. As the carbon content increases, the impact strength decreases and the cold brittleness threshold increases. An increase in the concentration of C leads to a change in electrical properties: resistance and coercive force increase, magnetic permeability and magnetic induction density decrease.

As carbon increases, casting properties, workability, cutting and weldability deteriorate. Cutting low-carbon steels is also difficult.

Sulfur in steel

Sulfur is a harmful impurity, the main sources of which are pig iron and ore used in steel smelting. It is able to dissolve in liquid iron, and during crystallization it forms FeS.

Iron sulfide forms a eutectic with iron with a low melting point, which is located along the grain boundaries. When technologically heated to the temperature of metal pressure treatment, it melts, and when deformed, it becomes the cause of tears and cracks.

This phenomenon is called red brittleness, since steel at a temperature of 900-1000℃ becomes bright red.

An increase in sulfur content has a nonlinear effect on the cold brittleness threshold: first it increases, and with an increase in the MnS content it decreases. Sulfur has a negative effect on weldability and corrosion resistance.

Phosphorus in steel

Phosphorus is one of the harmful impurities of steel, the source of which is charge materials, mainly cast iron. It is capable of dissolving in significant quantities in ferrite, which leads to distortion of the crystal lattice. At the same time, there is an increase in tensile strength and yield strength, a decrease in ductility and viscosity. An increase in phosphorus content causes an increase in the cold brittleness threshold and a decrease in the work of crack development.

Phosphorus is highly susceptible to segregation, which leads to a sharp decrease in viscosity in the central part of the ingot. Currently, there is no technology for deep purification of steel from phosphorus.

Optical emission spectral analysis C, S, P

Optical emission spectrometers are universal instruments that can solve a wide range of analytical problems. Their work is based on the principles of atomic emission spectral analysis of the elemental composition of matter:

• the spectrum of excited atoms and ions is individual for each element;
• the intensity of the spectral line depends on the concentration of the element in the test sample.

Emission spectral devices are widely used in metallurgy, due to the following advantages of the method:

• Possibility of studying samples in different states of aggregation.
• The analysis is non-destructive.
• The number of elements studied is practically unlimited. These include carbon, sulfur and phosphorus, which are of particular interest to metallurgists.
• To conduct a test, a small amount of a substance is sufficient as a sample.
• High sensitivity and accuracy.
• Expressiveness.
• Possibility of conducting certification analysis.

To analyze carbon, sulfur and phosphorus using emission spectrometers, certain conditions must be created in the device, namely: an oxygen-free atmosphere. Otherwise, it is not possible to determine elements whose wavelength is shorter than 185 nm. Currently, oxygen removal in the device is carried out in two ways:

• by pumping with inert gas;
• vacuuming.

Each deoxygenation system has certain operating and maintenance features, so when choosing a device for analyzing carbon, sulfur and phosphorus, their advantages and disadvantages should be taken into account. This will allow you to select a spectrometer that optimally matches the analytical task, the requirements for the accuracy of research results, and has satisfactory economic indicators.

Optical emission devices involving pumping with inert gas

Argon is most often used in spectral instruments for deoxygenation. To remove oxygen, one of the following systems is provided:

• Open. As a result of purging, oxygen is displaced, and inert gas is removed from the device into the surrounding atmosphere.
• Closed. When the inert gas passes through, oxygen is captured, which is subsequently purified using a filter. The gas continues to move through a closed system, the pressure in which is provided by the pump.

Devices with an open deoxygenation system are characterized by simple design and lower cost. However, in this case, the degree of purification is at a low level, and argon is consumed irrevocably. The use of such spectrometers is advisable when requirements for analytical characteristics are reduced, both on the part of the consumer and on the part of the manufacturer.

The design of devices with a closed deacidification system becomes more complicated, since additional components and their maintenance are required to ensure functionality:

• Pump with power supply.
• Gas cylinder to compensate for losses.
• Additional filter element.

Each of these instrument components requires maintenance and consumables require replacement, which is associated with additional costs. In addition, as a result of unprofessional actions of maintenance personnel, there is a risk of air in the system when replacing the filter. Eliminating the consequences of this requires not only additional material costs, but also time.

Optical emission devices with a vacuum system

The vacuum system allows to obtain a low residual oxygen concentration, which is many times lower than in an open deoxygenation system and comparable to the best results obtained in closed ones. It should be noted that there is no need to use inert gas.

This oxygen removal system is used in the most advanced spectral instruments. They are equipped with an oil pump, which is complemented by special oil traps. In addition, a valve is provided that, in the event of an emergency power outage, prevents damage to the spectrometer by oil as a result of its penetration into the vacuum line.

Two-stage oil foreline pumps are the most preferred equipment compared to oil-free diaphragm models. They have a comparable cost, but at the same time are tens of times superior to the latter in terms of oxygen removal, and also have a significant service life and are much easier to maintain.

Universal desktop and stationary spectrometers Iskroline 100/300 are excellent examples of devices in which a vacuum system is implemented to remove oxygen. They are capable of determining more than 70 elements, which include carbon, sulfur and phosphorus, with a detection limit of up to 0.0001%. The devices allow for quick and accurate spectral analysis of steels, and are characterized by high spectral resolution, high accuracy of measurement results and high quality manufacturing.

Source: https://www.iskroline.ru/analysis/analiz-csp/

Iron (Fe) and its compounds, production and use of iron

There are several theories about the origin of the word “iron,” which largely depend on the region and dialect.

The Russian name, to which we are all accustomed, has Proto-Slavic roots “želězo”, which in turn apparently came from the Greek “χαλκός”, which translated means “iron and copper”.

But be that as it may, there is one indisputable fact - the use of iron was carried out back in the 4th millennium BC, because It was from this period that ancient products made from this material were found.

Popular historical items include jewelry from Egyptian tombs (over 3000 BC) and a dagger from the ancient city of Ur (Sumer), from where, according to the Holy Scriptures, God called Abraham to come out.

The first people who began to smelt Fe were the Hutts, who lived in the territory of today's Southeast Turkey around 2000 BC. Archaeologists received this information from the ancient texts of the Hittite king Anitta, who conquered the Hattians with his people.

The first information about the production of steel from iron appeared in the writings of Aristotle, from the legend of the Argonauts. The Khaliba people carefully washed the river sand, sifting out heavy fractions of hematite and magnetite, which were then melted in a furnace to obtain a silvery stainless metal.

iPhone XS vs iPhone XR - does it make sense to pay more?

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Total information

Location on the periodic table D.I. Mendeleev: in the old version - IV period, IV row, VIII group, in the new version of the table - 8 group, 4 period.

• Atomic number – 26
• Atomic mass – 55.845
• Electronic configuration – [Ar] 3d6 4s2
• Melting point (°C) – 1538.85, or 1812 K.
• Boiling point (°C) – 2861, or 3134 K.
• CAS: 7439-89-6

Physicochemical characteristics. Iron is a silvery-white metal with a grayish tint, which in its pure form is highly ductile, but when combined with carbon it becomes harder and at the same time brittle. It has the property of being magnetized and changing its crystal structure (polymorphism) depending on the melting temperature.

The physical properties of Fe are very similar to two other metals - nickel (Ni) and cobalt (Co), which is why their combination is called the “iron triad”.

Upon contact with air, provided that the ambient temperature is not higher than 200 ° C, iron is covered with a dense oxide film, which prevents the further process of its oxidation. In a humid environment, the metal is covered with a layer of rust, which has a loose nature in its structure, which is why Fe is constantly exposed to moisture and oxygen, gradually destroying it.

Fe oxidation states: 2 and 3.

Biological role and functions of iron in the body

The body of an average adult person contains approximately 3-4 g of iron. Fe is the most abundant in blood plasma – about 3.5 mg. In addition, in percentage terms, ferrum in the body is present in the following forms - hemoglobin (68%), ferritin (27%), myoglobin (4%), transferrin (1%).

One of the main functions of iron in humans is as a catalyst for air exchange. We already wrote about this at the beginning of the article - hemoglobin, which mainly consists of the trace element considered today, binds to oxygen and delivers it to all parts of the body through the bloodstream; after delivery, it binds to carbon dioxide and carries it back to the lungs, and then , we exhale it.

Ferrum performs many other useful functions, including:

• Participates in the process of hematopoiesis - without it hemoglobin and myoglobin cannot be formed;
• Ensures the functioning of the endocrine system, maintaining the functioning of the thyroid gland;
• Indirectly participates in DNA synthesis, because is part of various enzymes, for example, ribonucleotide reductase;
• Provides the activity of interferons and other immune cells, due to which it participates in protecting the body from infection and various unfavorable factors;
• Being part of the liver cells, it takes part in cleansing the body of toxins, which can be spoiled foods, alcohol, medications, waste products of pathogenic microflora (bacteria and other infections), etc.;
• It has a beneficial effect on the metabolism (absorption) of B vitamins, which are directly involved in the performance of the cardiovascular and nervous system;
• Participates in the processes of formation and normal growth of the body, which is important for children;
• Maintains healthy hair, nails, and skin;
• Participates in many redox processes, being part of various oxidation enzymes;
• Prevents the development of anemia (anemia) and other diseases of the circulatory system;
• Takes part in intracellular metabolic processes;
• If we take into account the fact that ferrum takes part in the transport of oxygen throughout the body, not the last such organ is the brain, oxygen starvation of which negatively affects the mental and nervous function of a person or animal.

More on the topic Camera failure on Samsung: what to do with any Galaxy model

iPhone XS vs iPhone XR - case materials, colors, design

These three things are different in smartphones. Although, at a superficial glance at the iPhone XS and iPhone XR, the difference between them in terms of design is not particularly noticeable, but it is there. Firstly, the budget iPhone has a larger notch and dark frames. This is neither bad nor good - it just is, but you pay attention to it if you look at the two flagships lying next to each other.

Secondly, phones have different body materials. Yes, both devices are clad in a glass body, but the iPhone XR has two pieces of glass held together by a matte aluminum frame, while the iPhone XS has a polished steel frame. Thirdly, smartphones are available in different color variations: iPhone XR is available in black, white, blue, yellow, coral and red, and iPhone XS in silver, black and gold. In this regard, the budget iPhone is in a better position.

Daily requirement

Recommended daily doses of potassium depending on gender and age:

• Children and adolescents under 18 years of age – 4-18 mg;
• Adult men – 10 mg;
• Adult women – 20 mg;
• During pregnancy (in the second half and 3 months after birth) - up to 30-35 mg.

The daily dose of iron increases with heavy physical activity (sports, hard work, high physical activity), bleeding (menstruation, trauma, postoperative period), strict diets, diseases of the circulatory system (anemia, blood donation).

iPhone XS vs iPhone XR - dimensions, protection

An important factor when choosing a new smartphone is its size. Shovel smartphones have already fed up buyers: people want comfort, which is why we must talk about the differences in size and weight of Apple's new top-end smartphones:

• iPhone XS: 143.6x70.9x7.7 mm, 177 g
• iPhone XR: 150.9x75.7x8.3 mm, 194 g

The conclusion from this section is simple: if you need a compact smartphone, buy the iPhone XS.

The comfort of contact with a smartphone is affected not only by its dimensions, but also by peace of mind for its safety. In this regard, the more preferable option is iPhone X. It has protection against dust and moisture according to standard IP68. By the way, this gadget model was equipped with the ability to withstand salt water - this is a serious innovation and an argument in favor of buying an iPhone XS. What about the iPhone XR? The budget iPhone is protected according to the IP67 standard (immersion up to 1 meter for 30 minutes). Nothing special here.

Iron deficiency - symptoms

Iron deficiency in the body is expressed by the following symptoms and conditions:

• Development of anemia;
• Weakness, increased fatigue, dizziness, constant desire to sleep;
• Deterioration of mental function and other brain functions;
• Neurological disorders, depression;
• Dry and pale skin;
• Increased dryness and brittleness of nails;
• Dryness, fragility, hair loss and accelerated graying of hair;
• At the slightest drop in temperature, a person feels severe cold;
• Rapid weight gain, development of obesity;
• Inflammatory processes in the oral cavity – stomatitis, gingivitis;
• Impaired taste;
• Digestive dysfunction, accompanied by lack of appetite, nausea, flatulence;
• Geophagy – the desire to eat chalk, earth and other substances unusual for humans;

iPhone XS vs iPhone XR – screen comparison

The weakest point of the iPhone XR is its screen. Despite all the compliments from Apple, the quality level of the iPhone 10R display is 2013. Not only the type of matrix plays a role here: the iPhone XR has high-quality Super Retina, and the iPhone XR has Liquid Retina, but also the resolution. Of course, on the XR you won’t see individual pixels, but when compared to the XS, the difference will be noticeable - that’s a fact.

Application of iron

The use of Fe depends on its form, but generally speaking, it is advisable to use it for medicinal purposes in the following cases:

• Various diseases - anemia, malaria, hookworm and other helminthic infestations, enteritis, hypochlorhydria, malabsorption syndrome, chronic renal failure (CRF), cachexia, celiac disease, Crohn's disease;
• In case of heavy blood loss - trauma, menstruation, postoperative rehabilitation;
• Pregnancy and breastfeeding;
• When playing sports;
• Rapid weight loss;
• Hemodialysis;
• A period of rapid child growth or puberty.

Industrial iron is produced by smelting iron and steel.

Cast iron is an alloy of iron with impurities of silicon, manganese, sulfur, phosphorus, and carbon. carbon in cast iron exceeds 2% (in steel less than 2%).

Pure iron is obtained:

• in oxygen converters made of cast iron;
• reduction of iron oxides with hydrogen and divalent carbon monoxide;
• electrolysis of the corresponding salts.

Cast iron is obtained from iron ores by reduction of iron oxides. Iron smelting is carried out in blast furnaces. Coke is used as a heat source in a blast furnace.

Source: https://bonus-mts.ru/cem-otlicaetsya-ipone-r-ot-s/

The benefits and harms of feijoa for the male body, how does the fruit affect potency?

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An oblong green fruit with an unusual taste contains a lot of iodine and vitamins. The beneficial properties of feijoa for men include the prevention of vitamin deficiency, kidney problems, colds, gastrointestinal diseases, and impotence of various etiologies. But the product should be used with caution, as it has contraindications and, moreover, a large amount of the fruit can cause harm.

Compound

The taste of the exotic berry is reminiscent of a combination of pineapple and strawberry with the sourness characteristic of kiwi or gooseberry. The fruit is distinguished by its low calorie content - only 9 g of carbohydrates and 60 kilocalories per 100-gram serving. The health benefits of feijoa are explained by its vitamin and mineral composition.

Vitamin	Amount mg/100 g	% Daily Value for Men
C	33	36,7
B9	0,024	5,8
B5	0,23	4,6
B6	0,068	3,4
K	0,0035	2,9
PP	0,3	1,5
B2	0,018	1
H	0,0004	0,8
B1	0,007	0,5
Microelement
Cobalt	0,0014	14
Chromium	0,007	14
Iodine	0,02	13,4
Molybdenum	0,006	8,6
Manganese	0,085	4,2
Copper	0,004	4
Selenium	0,002	3,4
Iron	0,14	0,8
Fluorine	0,03	0,8
Zinc	0,06	0,5
Macronutrients
Silicon	14	43,6
Potassium	174	7
Phosphorus	19	2,3
Magnesium	9	2,4
Calcium	18	1,8
Sulfur	0,5	5
Chlorine	8	0,3
Sodium	3	0,2

In addition, it contains many amino acids:

• glutamic and aspartic acids;
• alanine;
• lysine;
• leucine;
• arginine;
• valine;
• glycine;
• tyrosine;
• threonine

As well as Omega-3 and 6 fatty acids. It should be borne in mind that the peel is the most saturated with nutrients, so it is recommended to consume the whole fruit.

11 factors why feijoa is beneficial for the male body

vitamins, amino acids and other elements allows the fruit to act as a therapeutic or prophylactic agent.

The benefits of feijoa for men are as follows:

• elimination of hypovitaminosis;
• strengthening the immune system, fighting colds;
• normalization of hormonal levels, and consequently - improvement of libido and potency;
• positive effect on the nervous, digestive and cardiovascular systems;
• improvement of blood circulation and metabolism, which has a beneficial effect on the speed of recovery and maintaining shape;
• prevention of the occurrence of cancer cells, combating their spread;
• relieving inflammation;
• replenishment of iodine deficiency;
• regulation of cholesterol levels;
• removal of toxins and waste;
• preventing the development of kidney pathologies.

The aromatic fruit will improve your well-being in case of many problems:

When used externally, it treats acne and nail fungus.

To get the maximum amount of nutrients from the berry, it is recommended to consume it whole. The peel contains iodine, antioxidants, and tannins. The pulp contains ascorbic acid. Those who like to eat the fruit with a spoon, choosing only the pulp, should save the skin and brew tea with it.

Contraindications and harm

Like any other fruit, the described fruit is not always healthy. Feijoa has the following contraindications:

• allergy to berries or individual intolerance;
• hyperthyroidism - overactive thyroid gland;
• diabetes;
• gastritis caused by high acidity;
• the presence of calcium oxalate in the urine;
• gout.

It is not recommended to combine the berry with milk or consume it unripe. If you are obese, you should be careful due to the content of easily digestible carbohydrates.

Failure to comply with the consumption norm can cause an increase in the level of thyroid hormones and unpleasant reactions from the nervous system: increased excitability or apathy. The optimal amount is 3–5 pieces per day.

The effect of feijoa on potency

The product indirectly affects the reproductive system. The benefits of feijoa for potency are explained:

The beneficial substances of the fruit have a cumulative effect - to feel the effect on potency, you will need to include it in your diet for at least a month.

Where to buy, how to choose?

You can buy exotic berries in supermarkets and food markets from October to the end of winter. The green skin should be smooth, without dents or dark spots. When pressing, press down, but not too much.

Only ripe fruits are useful, but it is not always possible to determine ripeness when purchasing. If the cut flesh is white and hard, you should wait a few days - the remaining feijoas will ripen (the proximity to bananas will speed up the process). Brown color indicates the opposite situation; it is not recommended to eat such fruits (they are overripe). The “correct” berry will be soft, translucent, and yellowish inside.

Feijoa for male power: effective recipes

Since the product has a positive effect on the body only when regularly included in the diet, the question arises of how best to eat it.

The tropical fruit can be consumed not only in its pure form: many recipes allow you to increase the usefulness of feijoa for male power.

Jam without cooking

A quick preparation that retains its beneficial properties and can be stored for several months. You will need:

The ingredients are taken in equal proportions and crushed in a blender to a puree. If desired, add lemon (1:1 to the total mass). It is recommended to place the resulting jam in sterilized jars with tight lids and store them in the refrigerator.

Ice cream

To make an unusual but healthy ice cream you need several ingredients:

• feijoa - 150 g;
• sugar + glucose - 50 g each;
• lemon juice - 10 g;
• pistachios - 50 g;
• powdered sugar - 20 g.

Combine the main component with sugar, glucose and juice in a blender, freeze in molds. Mix ground nuts with powder, roll the finished ice cream in the sprinkles. Glucose is needed for softness.

Feijoa with honey

Individually useful products complement each other well. The finished dish increases the amount of B vitamins, microelements, enzymes, and antibacterial substances. To feijoa with honey you can add:

• nuts - rich in healthy fats and vegetable protein, have a positive effect on men's health;
• citrus fruits (orange, tangerine and others) - will increase the content of vitamins;
• ginger - will further strengthen the immune system and improve potency.

Traditionally, all ingredients are crushed, the proportions are to taste, the minimum amount of honey is a quarter of the volume.

Green smoothie

A nutritious shake will be a tasty and healthy snack or addition to a meal. Recipe ingredients:

• 2 feijoas and kiwi each;
• mint sprig;
• 150–200 ml yogurt;
• a teaspoon of honey or sugar.

The products must be mixed in a blender bowl. Yogurt can be replaced with another fermented milk drink (kefir or fermented baked milk, for example).

Chutney

Fruit sauce, prepared according to Indian traditions, goes well with vegetable and meat dishes and has an exotic taste. To prepare you will need:

• feijoa - 1 kg;
• onion - 300 g;
• vinegar - 40 g, preferably apple or wine;
• garlic - medium head;
• salt - 10 g;
• cloves, cinnamon, ginger, black and cayenne pepper - to taste (traditionally, a pinch).

Recipe: chop feijoa, garlic and onion with a knife, cook over low heat for an hour and a half. Add vinegar, salt, spices, cook for another 20 minutes. Chutney can be stored in sterile, sealed jars for up to six months.

Reviews

Those who try feijoa for the first time often complain about the specificity of taste and smell, explained by the iodine content. It should be remembered that acidity and astringency are a sign of immaturity; a ripe fruit has sweet, tender pulp. An unpleasant taste for some can be masked with honey, nuts, and other additives. By the way, despite the fact that large “specimens” are more expensive, the size does not affect the content of useful nutrients. So you can get it cheaper.

Men seeking to lose weight (it is a proven fact that excess weight negatively affects potency) achieved good results by replacing other sweets with tropical fruit. A positive effect can only be obtained by following a healthy diet for a long time and engaging in physical activity.

The greatest benefits of feijoa for the male body are noted in regions characterized by low iodine content. Most of those who used it noticed a decrease in susceptibility to colds, increased tone, activity, increased libido, and erection. The fruit also helps with problem skin - ingestion helps remove toxins, and applying the crushed mass to acne helps relieve inflammation and reduce the secretion of the sebaceous glands.

Most men who have consumed the described exotic product answer affirmatively to the question of whether this berry is good for health. But you shouldn’t expect instant results - during the season you need to regularly include fresh fruit in your diet, not forgetting to prepare some for the rest of the year. If you don’t want to waste time on cooking, you can simply freeze it.

Kirill, 38 years old:

“I have problems with potency since early youth. It all started with psychological erectile dysfunction and gradually developed into a weak erection. I fight in every possible way. In the first years I took Sildenafil SZ, Viagra, Cialis, Levitra for a long time, but my health began to suffer. I went to the doctor, he said that I couldn’t stay on synthetic stimulants any longer, otherwise I wouldn’t live long.

In general, I switched to folk remedies, few of which really help. A populist friend advised me to include feijoa in my diet on a regular basis, and also try M-16 spray, which is also natural, applied to the penis before sex. The situation began to improve, now everything is more or less normal. At the same time, I signed up for the gym, go to the pool a couple of times a month, and gave up bad habits.

Maximum, a glass of champagne on New Year’s Eve or the birthday of loved ones.”

Vitaly, 45 years old:

“If you judge like this, then literally every product is useful. This may be true, but the effect is also the same, that is, minimal, and only if it is constant. Feijoa began to “eat” when he undermined his immunity, at the same time, he lost almost completely his attraction to his wife. In addition, I took a bunch of vitamins, supplements and other herbal products. My health improved, but it took more than six months. But without chemicals!!!”

Source: https://malepotency.ru/fejhoa-dlya-muzhchin.html

Stainless steels: how composition affects properties

Alloy steels occupy a significant share of the metallurgical products market. These include the so-called “stainless steels” - a group of alloys characterized by increased resistance to corrosion. Since their appearance, the range of such steels has expanded to several hundred items. Therefore, a system for their classification and labeling was developed.

It is worth noting that the name “stainless steel” does not entirely correctly reflect its properties. Any iron-carbon alloy is exposed to oxygen and aggressive substances, but for this to affect its performance properties, it takes different times. Therefore, stainless steels are more correctly called corrosion-resistant.

By composition

Chromium, nickel, vanadium, molybdenum, titanium and some others are used as alloying additives that increase the resistance of the iron-carbon alloy to rust formation.

Corrosion resistance is also increased by manganese and silicon introduced to deoxidize and neutralize sulfur. Based on the main alloying elements, stainless steels are classified as chromium, manganese, etc.

Some additives are used to impart special structural or technological properties to steels, for example, to crush carbides and increase impact toughness.

The basic alloying elements of stainless steel are chromium and nickel. They both enter into solid solution with iron and increase corrosion resistance.

When oxidized, they form a thin oxygen-impermeable film on the surface of a steel product, resistant to chemical, electrochemical and atmospheric influences. Nickel expands the austenite region in iron-carbon alloys.

Chromium narrows it, but is a carbide-forming element and binds carbon. The ratio of nickel and chromium has a decisive influence on impact strength, weldability and ability to withstand cold deformation.

Carbon, as one of the essential components of steels, negatively affects corrosion resistance. However, the hardness and wear resistance of steel depends on its content. For example, 95Х18 has less pronounced corrosion-resistant properties compared to 40Х13, despite its higher chromium content.

By properties

A more clear idea of ​​alloys is given by dividing them into groups according to properties:

• Corrosion resistant. Steels are highly resistant to atmospheric corrosion and can be used under normal conditions in a loaded state. Examples include stainless steel used for the manufacture of utensils and equipment for the food industry: 08Х18Н10, 20Х13, 30Х13.
• Heat resistant. A distinctive feature of such alloys is their high resistance to scale formation at high temperatures. Heat-resistant stainless steels are used for the manufacture of heat exchangers for boiler and pyrolysis plants (15Х28), valves for automobile and aircraft engines (40Х10С2М), parts for heating metallurgical furnaces (10Х23Н18).
• Heat resistant . A number of alloys have been developed that can operate under load at high temperatures without significant deformation and destruction. They use complex alloying systems (05Х27У5, 15Х12ВН14Ф, 37Х12Н8Г8МФБ). Steel type 20Х13 also has moderate heat resistance.

By structure

Based on their microstructure, stainless steels are divided into the following classes:

• austenitic;
• ferritic;
• martensitic;

In addition to them, there are intermediate groups:

• austenitic-ferritic;
• martensitic-ferritic;
• martensitic-carbide.

Heat treatment has a great influence on corrosion resistance, since it affects the phase composition of most stainless steels. Stability decreases when carbide heterogeneity occurs. This phenomenon is caused by the so-called intercrystalline corrosion.

When steels are heated to temperatures in the range of 500 – 800 °C, chains of carbides and areas with a reduced chromium content are formed at the grain boundaries. In the body of the grain, the content of alloying elements remains high. This type of corrosion is often observed in weld areas.

To combat this phenomenon, the steel composition is stabilized by introducing a small amount of titanium.

Austenitic steels

During crystallization, austenitic steels form a single-phase system with a face-centered crystal lattice. One of the most prominent representatives of the class is alloy 08Х18Н10.

Due to the high nickel content in stainless steels of this class (up to 30%), the austenite phase remains stable down to – 200 °C, and the carbon content does not exceed 0.12%. Steels with this structure are characterized by the absence of magnetic properties.

Most of them have good machinability.

Austenitic steels are necessarily subjected to heat treatment - hardening, tempering or annealing. The cooling rate practically does not change the hardness, but it affects the resistance to liquid and gaseous aggressive media, stabilizes the grain size and resistance to deformation.

Additional elements are introduced into the alloying systems of austenitic chromium-nickel steels:

• molybdenum – to prevent pitting and operation in reducing atmospheres
• titanium and niobium – for protection against intercrystalline corrosion.
• silicon – to increase acid resistance;
• manganese - to improve casting qualities.

Ferritic steels

This class includes chromium steels with low carbon content. They have a body-centered cubic lattice, which determines their magnetic properties.

Ferritic steels have lower corrosion resistance compared to austenitic steels and cannot be strengthened by heat treatment, but have higher technological properties. They are easier to machine and weld better, and their cost is significantly lower.

At temperatures of 300 – 400 °C, steels acquire high ductility, and they can be used to produce volumetric stamped parts of complex shapes.

chromium in such steels reaches 27%. Molybdenum, titanium and aluminum are used as stabilizing additives.

Martensitic steels

Alloys of this class contain at least 0.15% carbon and 11% chromium. Martensite has a microscopic needle-like structure and, when magnified, looks the same as carbon steel after hardening.

The crystal lattice has a tetragonal shape and is characterized by high internal stresses. This determines high strength properties and hardness. For example, for 40X13 it is up to 52 - 55 HRC.

Molybdenum, niobium, vanadium and tungsten are introduced as additional alloying elements. Martensitic steels, due to their high hardness, are difficult to cut and have low ductility.

One of the main technological properties of corrosion-resistant steels with this structure is the ability to self-harden. Martensitic transformation occurs upon cooling in air. To increase heat resistance, steel after hardening is tempered with sorbitol or troostite.

Source: https://acea-spb.ru/stati/nerzaveusie-stali-kak-sostav-vliaet-na-svoistva

The influence of carbon on the structure of steels

The maximum solubility of carbon in alpha iron is observed at a temperature of 721 C and is 0.018%. In the case of quenching, carbon may remain for some time in the alpha solution, but very soon phase separation begins through the aging mechanism.

In a solid alpha solution, carbon can form either a homogeneous solution, which happens very rarely, or, most likely, an inhomogeneous solution with the formation of clusters in places of distortion of the atomic lattice (grain boundaries, dislocations).

The latter option is the most possible state of an alpha solid solution.

Components of the structure of iron-carbon alloys

To analyze the effect of carbon content on iron-carbon alloys, it is necessary to characterize each of their structural elements. After slow cooling, steels consist of ferrite and cementite or ferrite and graphite.

 Ferrite

Ferrite is ductile. In the annealed state, ferrite has a high elongation (about 40%). Its Brinell hardness ranges from 65 to 130 C depending on grain size and it is highly magnetic up to a temperature of 770 ˚C. At a temperature of 723 °C, ferrite dissolves 0.02% of carbon, and at room temperature, only thousandths of a percent of carbon remains in solution.

 Cementite

Cementite is brittle and very hard. Its Brinell hardness is about 800. Cementite is a weak conductor of electric current and heat. It has a complex rhombic atomic lattice. Usually divided:

• primary cementite, which crystallizes from the liquid phase along the CD line;
• secondary cementite, which is released from the solid gamma solution along the ES line;
• tertiary cementite, which is released from the alpha solid solution along the PQ line.

Graphite

Graphite is soft. It is a poor conductor of electric current, but a good conductor of heat. Graphite does not melt even at a temperature of 3000-3500 ˚C. It has a hexagonal atomic lattice with an axial ratio greater than 2.

Austenite

Austenite is soft (but harder than ferrite) and ductile. The elongation of austenite is 40-50%. It has lower conductivity of heat and electricity than ferrite. Austenite is paramagnetic. It has a face-centric cubic lattice.

Change in steel structure with increasing carbon content

Let’s “walk” along the carbon content axis in the section of the state diagram of the iron-carbon system, which corresponds to steels (Figure 1): from 0 to 2% carbon.

Figure 1 – Double iron-carbon phase diagram

Ferrite and pearlite

A further increase in carbon content leads to the appearance of a new structural component - eutectoid ferrite and cementite (pearlite). First, pearlite appears as a separate inclusion between ferrite grains, and then, with a carbon content of 0.8%, it occupies the entire volume. Perlite is a two-phase mixture that usually has a lamellar structure (Figure 3).

Figure 3 – Microstructure of pearlite in steel

Perlite and cementite

When the carbon content rises above 0.8%, secondary cementite is formed along with perlite. Secondary cementite is released in the form of needles (Figure 4).

Figure 4 – Microstructure of steel: secondary cementite (needles) and pearlite

The amount of cementite increases with increasing carbon content. At a carbon content of 2%, cementite occupies 18% of the microscope's field of view. When the carbon content is more than 2%, a eutectic mixture is formed.

Ledeburite

Alloys with a carbon content of 3.6% contain ledeburite. Ledeburite is a eutectic mixture of austenite with dissolved carbon and cementite. These high-carbon alloys are no longer considered steels, but hypoeutectic white cast irons.

Source: https://steel-guide.ru/metallografiya-stali/vliyanie-ugleroda-na-strukturu-stalej.html