What alloy is called steel

Steel: iron + carbon +

The “everyday” definition of steel goes something like this: “A hard and durable iron-based metal alloyed with a small amount of carbon and often other metals such as nickel, chromium, and manganese.” Although it cannot be said that this definition is completely incorrect, it hardly adequately reflects the concept of “steel”.

A more precise definition of steel might be: “An iron-based alloy that is highly deformable within a certain temperature range and contains carbon and often other alloying elements. In carbon and low-alloy steels the maximum carbon content is about 2%, in high-alloy steels - up to 2.5%. The dividing line between low-alloy and high-alloy steels is usually 5% metal alloying elements.  

Three phases of steel - ferrite, cementite and austenite

In principle, all steels are mixtures, or rather alloys, of iron and carbon. However, even the most common steels, so-called general purpose steels, have small but controlled amounts of manganese and silicon, as well as small and usually unavoidable amounts of phosphorus and sulfur. carbon in general purpose steels is usually from 0.05 to 1.0%.  

The mechanism of alloying iron with carbon differs from other alloy systems in that it is a two-stage process. In the first stage, iron combines with 6.67% carbon to form iron carbide, more commonly called cementite. Therefore, at room temperature, ordinary steel contains a mixture of cementite and ferrite. Both of them are phases.

A phase is a physically homogeneous and separated part of a material system. When steel is heated to 725 ºC, cementite, cementite, dissolves in the iron and a new phase is formed - austenite. Note that one should not confuse “steel phases” and “steel structures”.

Any steel can have only three phases, while there can be several structures, as well as mixtures of them.        

Steel classification

It is impossible to determine the exact number of steel compositions that currently exist. There are at least a thousand of them. There is no strict classification of steels. However, most often steel is divided into five groups, which suits most specialists who work with steel.

These five classes are:

carbon steels; alloy steels, sometimes called low-alloy steels; stainless steels - standards call them “corrosion-resistant”; tool steels;

special steels,

Special steels include steels with special properties that are needed for their use in specific operating conditions. In addition, these may be steels that are very similar to steels from the first four groups, but are still so different from them that they require a separate alloy designation.   

Why is steel the main one?

It would be unfair to claim that any one metal is more important than another. For example, without aluminum and titanium there would be no modern aircraft and spacecraft.

Steel, however, is much more widely used than any other metal. It is generally believed that the reason for steel's dominance is due to the abundance of iron ore and the ease with which iron can be extracted from the ore. Both are wrong. Iron is not the most abundant element. It is not so easy to extract it from ore, but copper, for example, is found in almost pure form in some areas of the world.  

What makes steel such an important material is its incredible flexibility in its processing and application. This flexibility is given to it by the variety of options for its structure and methods of deformation and heat treatment to achieve them.

Wide possibilities for the use of steel are provided by two of its important metallurgical phenomena:

1) iron is an allotropic element, that is, it can exist in more than one crystalline form;
2) the size of a carbon atom is only 1/30 of the size of an iron atom.

Iron is the basis of steel

All pure metals, as well as alloys, have individual phase diagrams, which are more often called phase diagrams. As a rule, the percentage of alloying element in the alloy is plotted along the horizontal axis. Temperature is plotted vertically. The diagram of pure iron is a straight line. When pure iron is cooled, it changes from one phase to another at a constant temperature.   

Pure iron solidifies at 1538ºC to form a crystalline structure called ferrite or delta iron. This phase has a body-centered cubic atomic lattice. With further cooling, reaching a temperature of 1395 ºС, the atoms are rearranged into a 14-atomic lattice, which is called gamma iron.

As cooling continues below 910°C, the iron structure returns to the 9-atomic lattice or alpha iron. The change at 770°C simply denotes a change from non-magnetic iron to magnetic iron and is not a phase change.

The entire field below 910 °C is ferrite down to room temperature and below.

Ferrite that forms above austenite is often called “delta ferrite,” while ferrite that forms below point A3 is called alpha ferrite, although structurally both are exactly the same.

The mechanism of allotropy is the most important property of iron, which provides it with the diversity of its structure and the flexibility of heat treatment of steels.

• Metastable iron-carbon phase diagram
• Austenite transformation

Source: https://steel-guide.ru/metallografiya-stali/stal-zhelezo-uglerod.html

5. What alloys are called steels and cast irons? Characterize their microstructures

Option25

1. Gears of rotary compressors, mud and oil pumps must have high wear resistance and good resistance to dynamic loads. Select marcus steel for the manufacture of gears with a maximum cross-section of 3540 mm. Give the chemical composition of steel, explain the purpose of alloying elements. Indicate a method for achieving high wear resistance of teeth and a heat treatment regime. Describe the final structure and mechanical properties in various parts of the gear cross-section.

2. The material of the pipes of some heat exchangers must have high thermal conductivity, corrosion resistance, and ductility. Select an alloy (в350 MPa, 45%) that satisfies the specified requirements. Give the grade, chemical composition, note its effect on the structure, mechanical and technological properties of the alloy.

3. Select grades of steel for pressing molds (operating temperature 200-250°C) of chemically active plastics containing mineral fillers with high hardness. Indicate the chemical composition and role of alloying elements. Give the heat treatment regime, final structure and hardness of the steel.

4. Select plastic for the manufacture of gears operating in aggressive environments. Indicate the classification group of plastic, describe its composition. Structure and physical and mechanical properties.

5. What are white, gray, ductile and ductile cast irons? How are they labeled and what properties differ from each other?

Option26

1. Assign a heat treatment regime for lightly loaded parts made of steel 40. Give its rationale and describe the structure and properties of the parts. Explain why satisfactory properties on products made from this steel can be obtained with a small cross-section.

2. Select grades of steel for critical fasteners (connecting rod bolts of piston compressors, bolts and studs of centrifugal pumps, flange connections of oil refining plants) that experience significant static and dynamic loads during operation. Indicate the chemical composition and purpose of alloying elements. Provide the heat treatment mode, final structure and mechanical properties of steel.

3. Select inexpensive steel for the manufacture of pipes and flanges and tube sheets welded to them for steam superheaters, steam pipelines operating up to a temperature of 550°C. Specify the steel grade, chemical composition, and alloying elements. Justify the heat treatment regime, bring the final structure and mechanical properties of steel.

4. Select high-strength plastic (b500600 MPa) for the manufacture of reaction apparatus bodies, main and pressure gas and oil pipelines, etc. Indicate the classification group of the material. Describe its structure and physical and mechanical properties.

5. What is steel annealing? Its types, purpose and microstructures depending on carbon content

Option27

1. Drilling of oil and gas wells is carried out using drill bits, the cutting tools of which (cones) are subject to significant shock loads and abrasive wear of the working teeth.

Formulate the requirements for mechanical properties for such a tool. Select the grade of steel for the manufacture of cutters, indicate the chemical composition and purpose of alloying elements.

Justify the technology and processing modes that provide the required complex of properties. Give the structure and hardness in different parts of the cutter section.

2. Select an alloy with strength b = 200300 MPa, from which a lightweight vessel for storing chemically active liquids can be made. Take into account that the manufacturing technology includes cold plastic deformation of the sheet blank with subsequent welding of the joints. Give the grade, chemical composition, structure, mechanical and technological properties of the alloy. Explain the influence of the method of forming the vessel on the mechanical properties of the alloy.

3. Select marcus steel with a strength of in1600 MPa for the manufacture of spring shock absorbers that reduce vibration of high-speed machines in chemical production (compressors, centrifuges, turbine units, etc.). Give the chemical composition of steel and the purpose of alloying elements. Indicate the heat treatment mode, final structure and mechanical properties of steel.

4. Select plastic for the manufacture of brake pads for lifting mechanisms of drilling rigs. Indicate the classification group of the plastic, describe its structure and characteristic properties.

Source: https://studfile.net/preview/5335883/page:3/

What alloy is called cast iron? — Metals, equipment, instructions

Cast iron is an alloy of iron and carbon. The percentage of iron contained is more than 90%. The amount of carbon ranges from 2.14-6.67%. Thanks to this element, the material has high hardness, but becomes brittle. This entails a deterioration in ductility and ductility. In some types, alloying elements are added to improve characteristics: aluminum, chromium, vanadium, nickel.

Characteristics of types of carbon metal

The iron-carbon diagram shows what cast iron is made of. In addition to iron, carbon is present in the form of graphite and cementite.

The composition of the cast iron alloy has varieties:

• White. The carbon present here is in a chemically bound state. The metal is strong, but brittle and therefore difficult to machine. In industry it is used in the form of castings. The properties of the material allow it to be processed with an abrasive wheel. The welding process causes difficulty, since there is a possibility of cracks due to the heterogeneity of the structure. Found application in areas related to dry friction. Has increased heat resistance and wear resistance.
• Half-hearted. It has increased fragility, so it is not widely used.
• Grey. GOST 1412–85 indicates what percentage of impurities this metal contains: 3.5% carbon, 0.8% manganese, 0.3% phosphorus, 0.12% sulfur and up to 2.5% silicon. The carbon present in the platelet form creates low impact strength. The characteristics of the type indicate that the material works better in compression than in tension. When heated sufficiently, it has good weldability.
• Malleable. A ferrite base of this type provides it with high ductility. When broken, it has a black, velvety color. It is obtained from white, which languishes for a long time at a temperature of 800-950 degrees.
• Highly durable. The difference from other types is the presence of spherical graphite. It is obtained from gray after adding magnesium to it.

Individual properties of metal

The material is characterized by certain characteristics. These include:

• Physical. Values ​​such as specific gravity or expansion coefficient depend on the carbon content of the metal. The material is heavy, so cast iron bathtubs can be made from it.
• Thermal. Thermal conductivity allows you to accumulate heat and retain it, distributing it evenly in all directions. This is used in the manufacture of frying pans or radiators for heating.
• Mechanical. These characteristics vary depending on the graphite base. The most durable is gray cast iron with a perlite base. A material with a ferrite component is more malleable.

Depending on the presence of impurities, a difference in the properties of the material appears.

These elements include sulfur, phosphorus, silicon, manganese:

• Sulfur reduces the fluidity of the metal.
• Phosphorus reduces strength, but makes it possible to manufacture products of complex shapes.
• Silicon increases the fluidity of the material, lowering its melting point.
• Manganese gives strength, but reduces fluidity.

Differences between cast iron and steel

To understand the difference between steel and cast iron, you need to consider their characteristics. A distinctive feature of cast iron is the amount of carbon. Its minimum content is 2.14%. This is the main indicator by which this material can be distinguished from steel.

iron in steel is 45%, and the percentage of carbon is up to 2. To determine the differences by eye, you need to pay attention to the color. Steel is light in color and cast iron is dark.

Only chemical analysis can determine the percentage of impurities. If we compare the melting point of cast iron and steel, then for cast iron it is lower and amounts to 1150-1250 degrees. For steel - around 1500.

To distinguish the material, you need to do the following:

• The product is lowered into water and the volume of displaced water is determined. Cast iron has a lower density. It is 7.2 g/cm3. For steel - 7.7−7.9 g/cm3.
• A magnet is applied to the surface, which attracts the steel better.
• The chips are rubbed using a grinder or file. Then it is collected in paper and wiped on it. Steel will not leave marks.

Pros and cons of the material

Like any material, cast iron has positive and negative sides. Positive qualities include:

• a wide variety of conditions.
• some types are highly durable;
• the ability to maintain temperature for a long time;
• environmentally friendly, which allows you to make dishes from it;
• resistance to acid-base environment;
• high hygiene;
• long service life and durability;
• harmlessness of the material.

However, there are also disadvantages. These include:

• when kept in water for a long time, the surface becomes covered with rust;
• high cost of material;
• low ductility of gray cast iron;
• fragility.

Cast iron is a metal characterized by a high carbon content. Thanks to this, it has qualities that are necessary for industrial and domestic purposes.

Source: https://spb-metalloobrabotka.com/kakoy-splav-nazyvaetsya-chugunom/

What alloys are called steels

There are several ways to classify alloys:

• by manufacturing method (cast and powder alloys);
• by the method of obtaining the product (casting, wrought and powder alloys);
• by composition (homogeneous and heterogeneous alloys);
• according to the nature of the metal - base (ferrous - Fe base, non-ferrous - base, non-ferrous metals and alloys of rare metals - radioactive elements base);
• by the number of components (double, triple, etc.);
• by characteristic properties (refractory, low-melting, high-strength, heat-resistant, hard, anti-friction, corrosion-resistant, etc.);
• by purpose (structural, instrumental and special).

Properties of alloys

The properties of alloys depend on their structure.

Alloys are characterized by structure-insensitive (determined by the nature and concentration of the elements that make up the alloys) and structure-sensitive properties (depending on the characteristics of the base).

The structurally insensitive properties of alloys include density, melting point, and heat of evaporation. thermal and elastic properties, coefficient of thermal expansion.

All alloys exhibit properties characteristic of metals: metallic luster, electrical and thermal conductivity, ductility, etc.

Also, all properties characteristic of alloys can be divided into chemical ones (the relationship of alloys to the effects of active media - water, air, acids, etc.

) and mechanical (the attitude of alloys to the influence of external forces).

If the chemical properties of alloys are determined by placing the alloy in an aggressive environment, then special tests are used to determine the mechanical properties.

So, in order to determine strength, hardness, elasticity, ductility and other mechanical properties, tensile, creep, impact strength, etc. tests are carried out.

Main types of alloys

Various steels, cast iron, alloys based on copper, lead, aluminum, magnesium, as well as light alloys are widely used among all kinds of alloys.

Steels and cast irons are alloys of iron and carbon, with the carbon content in steel up to 2%, and in cast iron 2-4%. Steels and cast irons contain alloying additives: steels – Cr, V, Ni, and cast iron – Si.

There are different types of steels; for example, structural, stainless, tool, heat-resistant and cryogenic steels are distinguished according to their intended purpose.

Based on their chemical composition, they are divided into carbon (low-, medium- and high-carbon) and alloyed (low-, medium- and high-alloy).

Depending on the structure, austenitic, ferritic, martensitic, pearlitic and bainitic steels are distinguished.

Steels have found application in many sectors of the national economy, such as construction, chemical, petrochemical, environmental protection, transport energy and other industries.

Depending on the form of carbon content in cast iron - cementite or graphite, as well as their quantity, several types of cast iron are distinguished: white (light color of the fracture due to the presence of carbon in the form of cementite), gray (gray color of the fracture due to the presence of carbon in the form of graphite ), malleable and heat resistant. Cast irons are very brittle alloys.

The areas of application of cast iron are extensive - artistic decorations (fences, gates), cabinet parts, plumbing equipment, household items (frying pans) are made from cast iron, and it is used in the automotive industry.

Copper-based alloys are called brasses; they contain from 5 to 45% zinc as additives. Brass containing 5 to 20% zinc is called red (tompak), and brass containing 20–36% Zn is called yellow (alpha brass).

Among lead-based alloys, two-component (lead alloys with tin or antimony) and four-component alloys (lead alloys with cadmium, tin and bismuth, lead alloys with tin, antimony and arsenic) are distinguished, and (typical of two-component alloys) with different contents of the same components different alloys are obtained. Thus, an alloy containing 1/3 lead and 2/3 tin - tertiary (ordinary solder) is used for soldering pipes and electrical wires, and an alloy containing 10-15% lead and 85-90% tin - pewter, was previously used for casting cutlery.

Aluminum-based two-component alloys – Al-Si, Al-Mg, Al-Cu. These alloys are easy to produce and process.

They have electrical and thermal conductivity, are non-magnetic, harmless in contact with food, and explosion-proof.

Aluminum-based alloys are used for the manufacture of lightweight pistons; they are used in carriage, automobile and aircraft construction, the food industry, as architectural and finishing materials, in the production of technological and household cable ducts, and in the laying of high-voltage power lines.

Examples of problem solving

Source: https://steelfactoryrus.com/kakie-splavy-nazyvayutsya-stalyami/

10 interesting facts about Kazan - the third capital of Russia

Kazan is called the fastest growing tourist destination. During its history, the city's territory has experienced many interesting events - from the foundations of the feudal khanate to gang wars that thundered throughout the country. But what has always distinguished Kazan from other cities is its originality and “separateness”.

Now Kazan is the capital of the Republic of Tatarstan, but during the Khanate it was a separate city that dreamed of capturing the Moscow Principality.

The unique culture of Kazan is associated with its multinationality and abundance of religions; this and some other curious and interesting facts explain the tourist love for the city.

10. Initially, the city served as a border fortress

The specific topographical location of the future Kazan predetermined its functions: initially the city existed as a border fortress .

There has previously been a lot of controversy surrounding the founding date of the city. Evidence from historians suggests that Kazan appeared back in 1005, but the first mention of the city dates back only to the 14th century.

Even more interesting is that the leadership of the Soviet Union in the 70s of the last century strongly opposed the idea that Kazan is older than Moscow itself, and even forbade celebrating the 800th anniversary of the city. Fortunately, by 2005 both the government and its mood had changed, and Kazan celebrated its 1000th anniversary.

The position of critics is explained precisely by the fact that for a long time Kazan did not function as a city, but was only an outpost in the north of Volga Bulgaria.

9. Capital of the former Kazan kingdom and khanate

After the collapse of the Golden Horde, one of the khans, Ulu-Muhammad, was thrown back to the Volga. He became interested in the fortified city of Kazan, from where he expelled the ruling prince there. Khan declared himself independent in 1438, creating his own feudal state - the Kazan Khanate, which later became known as the kingdom .

For more than a century, the Khanate existed autonomously. Inside it they were engaged in construction and architecture, stone carving. Eastern poetry and writing developed widely. They lived quite peacefully in the Khanate: warriors made a few forays into nearby cities only in times of troubles.

There were no people willing to approach Kazan - fortified and equipped with artillery - until Ivan the Terrible. He tried to subjugate the Khanate first through diplomacy, but then undertook a military campaign and forcibly annexed the territory to the Principality of Moscow.

8. One of the three oldest cities in Eastern Europe

The fact that in 2020 Kazan will be 1015 years old makes it not only the oldest city in Russia, but also one of the oldest settlements in what is now Eastern Europe . It is second only to Kyiv, founded according to various estimates in the 6th-10th centuries, and Prague, which appeared in the 8th century.

7. Was considered the largest city in the country

Kazan also has another record. Several times throughout its history, even after its inclusion in the Russian Empire, this particular city was called the largest in the country .

Thus, according to the census of 1798, Kazan could even then be considered a metropolis - 200 thousand people lived in it. For comparison, in Moscow at the same time there are 60 thousand less. Now the situation has changed: now the capital is 10 times ahead of Kazan in terms of the number of inhabitants.

6. The unfavorable situation in the city in the 80s - 90s was called the “Kazan phenomenon”

At the turn of the 80s and 90s, references to the “Kazan phenomenon” first appeared in the press . At that time, several gangs operated in the Tatar Autonomous Soviet Socialist Republic, terrorizing local residents. At the same time, the security forces tried not to notice them, fearing for the statistics.

It is curious that no so-called “concepts” existed in these gangs: young people were distinguished by boundless cruelty, they were not afraid of thieves in law or murderers who had already served time, and fights often ended in death.

Almost the entire city was divided into zones, each of which was “held” by a specific group. Often “Kazan” bandits went to Moscow for showdowns. The situation changed on its own under the influence of the new economic realities of perestroika.

5. The famous Kazan Cat - the hero of fairy tales and legends

Every tourist who comes to Kazan can immediately notice how loved cats are in the city. On the main street of the city - Bauman - there is even a monument to the famous Kazan Cat, with which many legends are associated .

According to one of them, popular prints with the image of the Kazan Cat with a mustache and bulging eyes were very popular in the past, because they could easily be seen as a parody of Peter I.

According to another fairy tale, a smart cat saved the Kazan Khan when soldiers of Ivan the Terrible were digging a tunnel in his palace.

And the last legend: it was cats from Kazan that were once taken to the Winter Palace so that they could exterminate the mice that were haunting Empress Elizabeth Petrovna. The descendants of many of them still “work” in the Hermitage.

4. A vibrant, cosmopolitan city

The multinational population of Kazan is what distinguishes the city from other territories of the country . Among the 1 million 177 thousand Kazan residents there are Tatars, Chuvash, Ukrainians, Russians, Mari, Udmurts, Bashkirs, and many others.

According to official statistics, there are 115 nationalities represented in the city, who live peacefully with each other. The diversity of traditions and customs makes Kazan a unique city with colorful holidays.

3. The city has 16 temples belonging to different religions

The multinationality of Kazan also shaped its unusual religiosity. In total, there are 16 temples in the city . The temple-museum, which is located in the village of Old Arakchino, deserves special mention. The sculptors gathered a synagogue, a pagoda, a mosque and an Orthodox church in one place, and the religious elements of the buildings directly refer to 16 world religions, some of which have already been forgotten.

Residents of the city consider the name “Kazan” symbolic, which, according to one version, comes from the word “cauldron” (“cauldron”). After all, here, like in a big cauldron, different religions and cultures are “cooked”.

2. A number of legends are associated with the coat of arms of Kazan

The coat of arms of Kazan depicts a creature that can be mistaken for both a snake and a dragon . A number of legends are also associated with this mythological creature. Thus, the Tatar land, rich in everything necessary, was always abundant in snakes, and they were ruled by the winged Zilant, who exterminated animals and people.

The sorcerers were able to drive Zilant to a nearby mountain, but even from there he annoyed people. Only with the help of magic was it possible to defeat the snake. In honor of this event, his image appeared on the coat of arms.

The towering Zilantova Mountain in Kazan also reminds us of the evil creature: during the time of Ivan the Terrible, the Assumption Monastery was built on it, which is now being restored.

1. The city is the third capital of Russia

Back in 2005, at the celebration of the 1000th anniversary of Kazan, Vladimir Putin called the city “the third capital of Russia,” and 4 years later the city authorities decided to patent this name .

It is interesting that the leadership of other cities did not like this news very much - many were indignant that Kazan, in terms of numbers and political influence, could not bear such a high-profile title.

The main rivals of the city for the right to be the “third capital” of the country are Nizhny Novgorod, Yekaterinburg, Omsk and others. But be that as it may, the new title attracted rivers of tourist flow to Kazan, which have not dried up to this day.

Source: https://top10a.ru/interesnye-fakty-o-kazani.html

Steel structure. Chemical, mechanical and physical properties

“Iron is not only the basis of the whole world, the most important metal of the nature around us,

it is the basis of culture and industry, it is an instrument of war and peaceful labor.”

 A.E.Fersman

Everyone knows that steel is the most important tool and structural material for all industries.

The metallurgical industry of Ukraine has more than 50 metallurgical plants and is strategically important for the country. Ukraine produces a wide range of rolled metal products, such as: rebar, circles, squares, rods, wires, strips, angles, beams, channels, sheets, pipes and hardware.

Steel

Considering this issue, let's start with the chemical composition.

Steel is a compound of iron (Fe) + carbon (C) + other elements dissolved in iron.

Iron in its pure form has very low strength, and carbon increases it.

Carbon improves some other indicators:

• hardness,
• elasticity,
• wear resistance,
• endurance.

 “Fe” in steel should be at least 45%, “C” - no more than 2.14% - theoretically, but in practice the % carbon concentration has the following range of values:

• Low carbon steels - 0.1-0.13%
• Carbon steels 0.14-0.5%
• High carbon – from 0.6%

The higher the percentage of carbon content in steel, the higher its strength and the lower its ductility. CARBON is a non-metallic element. Its density is 2.22 g/cm3, and melts at t -3500 °C. In nature, it is present in 2 polymorphic modifications - graphite (stable modification) and diamond (metastable modification), and in an alloy with iron:

• in free - graphite (in gray cast iron),
• when bound, it is a solid state - cementite.

Carbon in combination with iron is in the state of cementite , i.e. in a chemical bond with iron (Fe3C). The structure of cementite can be very different, and it depends on the formation process, carbon content and heat treatment methods.

Carbon is present in a free state in gray cast iron (GC), in the form of graphite. Gray cast iron has a porous metal structure and is very brittle; Cracks easily appear on it (especially during the welding process).

Chemical composition of carbon steels of ordinary quality (GOST 380-71)

Iron-carbon system

The structure of steel is studied using the state diagram of the iron-carbon system. It characterizes the structural transformations of steel and expresses the dependence of the structural state on temperature conditions and chemical composition.

State diagram of the iron-carbon system

The phase diagram contains critical points that are very important theoretically and practically for steel heat treatment processes and their analysis. Using the Fe-C diagram, you can determine the type of heat treatment, the temperature range of structure changes and predict the microstructure.

Steel structures

Iron-carbon alloys at different temperatures and different “C” contents have different structures and, accordingly, physical and chemical properties. One of these conditions is the cementite described above. And now about them:

Austenite – a solid carbon structure in gamma iron – contains “C” up to 1.7% (t > 723° C). As the temperature decreases, austenite decomposes into ferrite and cementite, and a lamellar structure—pearlite—appears.

Ferrite is a solid solution of “C” in α-iron - at t> 723-768°C, the concentration of “C” is 0.02%, and at t 20°C about 0.006% “C”. It is very plastic, not hard and has low magnetic properties.

Cementite is iron carbide Fe3C. Concentration "C" 6.63%. Cementite is brittle and its hardness is HB760-800.

Pearlite is a mechanical mixture of ferrite and cementite, formed during gradual cooling during the decomposition of austenite. Based on the size of the cementite particles, perlite has different mechanical properties. "C" -0.8%.

Ledeburite (cast iron structure) is a mixture formed from the crystallization of a liquid alloy of cementite and austenite. Ledeburite is very hard, but brittle. Concentration "C" -4.3%

Properties of steel

Of course, it is not only carbon that affects the properties of steel. The composition of additional elements and their quantity impart certain properties to steel. Impurities can be beneficial or harmful. Good impurities affect exclusively the crystals themselves, while harmful impurities negatively affect the connection of crystals with each other. Good impurities include: manganese (Mn), silicon (Si). The bad ones: phosphorus (P), sulfur (S), nitrogen, oxygen and others.

Physical and mechanical properties of steel

The main physical properties of steel are:

• heat capacity;
• thermal conductivity;
• elastic modulus.
• The concept of elastic modulus of steel (E) is the ratio of a solid to deform elastically when subjected to a force. This characteristic directly depends on stress, or more precisely, it is a derivative of the ratio of stress to elastic deformation.
•  shear modulus (shear elasticity) (G) – a value measured in Pascals (Pa), which determines the elastic properties of a body or material and their ability to resist shear deformations. It is used to calculate shear, shear, and torsion.
•  coefficient of linear and coefficient of volumetric expansion with a change in temperature is a value showing the relative change in the linear dimensions or volume of a material or body with increasing temperature at a constant pressure.

The main mechanical properties of steel are:

• strength
• hardness
• plastic
• elasticity
• endurance
• viscosity

Indicators of mechanical properties of carbon steels of ordinary quality (GOST 380-71)

The main chemical properties of steel are:

•  oxidation state
•  corrosion resistance
•  heat resistance
•  heat resistance

The quality of steel is determined by various indicators of all its properties and structure. The properties of products made from this steel are also taken into account.

According to the quality of steel, they are divided into:

• ordinary quality,
• quality steel,
• high quality steel.

In this article we consider only the structure of steel and related concepts. The quality of steel, the composition of additional impurities and their properties will be discussed in the next publication.

Source: https://vikant.com.ua/news/chto_takoe_stal

What alloy is called steel

Many people know that steel is a product obtained by melting other elements. But which ones? What does steel contain? Today, this substance is a deformable alloy of iron and carbon (its amount is 2.14%), as well as a small proportion of other elements.

General information

It is worth noting that steel is an alloy that contains up to 2.14% carbon in its composition. An alloy containing more than 2.14% carbon is already called cast iron.

It is known that the composition of carbon steel and ordinary steel is not the same. If a conventional substrate contains carbon and other alloying (improving) components, then the carbon product does not contain alloying elements. If we talk about alloy steel, then its composition is much richer.

In order to improve the performance characteristics of this material, elements such as Cr, Ni, Mo, Wo, V, Al, B, Ti, etc. are added to its composition.

It is important to note that the best properties of this substance are ensured precisely by adding doped complexes, and not just one or two substances.

The material we are considering can be classified according to several indicators:

• The first indicator is the chemical composition of the steel.
• The second is the microstructure, which is also very important.
• Of course, steel differs in its quality and method of production.
• Also, each type of steel has its own application.

The composition can be considered in more detail using the example of chemical composition. Based on this feature, two more types are distinguished - alloy and carbon steels.

Among carbon steels, there are three varieties, the main difference of which is the quantitative carbon content. If the substance contains less than 0.3% carbon, then it is classified as low-carbon. of this substance in the region of 0.3% to 0.7% transfers the final product to the category of medium-carbon steels. If the alloy contains more than 0.7% carbon, then the steel belongs to the high-carbon category.

With alloy steels the situation is approximately the same. If the material contains less than 2.5% of alloying elements, then it is considered low-alloyed, from 2.5% to 10% - medium-alloyed, and from 10% and above - highly alloyed.

Microstructure

The microstructure of steel differs depending on its condition. If the alloy is annealed, then its structure will be divided into carbide, ferritic, austenitic, and so on. With a normalized microstructure of the substance, the product can be pearlitic, martensitic or austenitic.

The composition and properties of steel determine whether a product belongs to one of these three classes. The least alloyed and carbon steels are the pearlitic class, the middle ones are martensitic, and the high content of alloying elements or carbon transfers them to the category of austenitic steels.

Production and quality

It is important to note that an alloy such as steel may also include some negative elements, a high content of which worsens the performance of the product. These substances include sulfur and phosphorus. Depending on the content of these two elements, the composition and types of steel are divided into the following four categories:

• The rank and file became. This is an alloy of ordinary quality, containing up to 0.06% sulfur and up to 0.07% phosphorus.
• High quality. of the above substances in these steels is reduced to 0.04% sulfur and 0.035% phosphorus.
• High quality. They contain only up to 0.025% of both sulfur and phosphorus.
• The highest quality alloy is assigned if the percentage of sulfur content is no more than 0.015, and phosphorus is no more than 0.025%.

If we talk about the process of producing an ordinary alloy, then most often it is produced in open-hearth furnaces or in Bessmer, Thomas converters. This product is bottled into large ingots. It is important to understand that the composition of steel, its structure, as well as quality characteristics and properties are determined precisely by the method of its manufacture.

Open hearth furnaces are also used to produce high-quality steel, but more stringent requirements are imposed on the smelting process in order to obtain a high-quality product.

Melting of high-quality steels is carried out only in electric furnaces. This is explained by the fact that the use of this type of industrial equipment guarantees an almost minimal content of non-metallic additives, that is, it reduces the percentage of sulfur and phosphorus.

In order to obtain an alloy of particularly high quality, they resort to the method of electroslag remelting. The production of this product is possible only in electric furnaces. After completing the manufacturing process, these steels are always only alloyed.

Types of alloys by application

Naturally, a change in the composition of steel greatly affects the performance characteristics of this material, which means that the scope of its use also changes. There are structural steels that can be used in construction, cold forming, and can also be case-hardened, tempered, high-strength, and so on.

If we talk about construction steels, they most often include medium-carbon and low-alloy alloys. Since they are mainly used for the construction of buildings, the most important characteristic for them is good weldability. Various parts are most often made from case-hardened steel, the main purpose of which is to work under conditions of surface wear and dynamic loading.

Other steels

Other types of steel include improveable steel. This type of alloy is used only after heat treatment. The alloy is exposed to high temperatures to harden it and then tempered in some environment.

The type of high-strength steels includes those in which, after selecting the chemical composition, as well as after undergoing heat treatment, the strength reaches almost a maximum, that is, approximately twice as much as that of the usual type of this product.

Spring steels can also be distinguished. This is an alloy that, as a result of its production, has received the best qualities in terms of elastic limit, load resistance, and fatigue.

Stainless steel composition

Stainless steel is an alloy type. Its main property is high corrosion resistance, which is achieved by adding an element such as chromium to the alloy composition. In some situations, nickel, vanadium or manganese may be used instead of chromium. It is worth noting that by melting the material and adding the necessary elements to it, it can obtain the properties of one of three grades of stainless steel.

The composition of these types of alloy is, of course, different. The simplest are considered to be ordinary alloys with increased resistance to corrosion 08 X 13 and 12 X 13. The next two types of this corrosion-resistant alloy must have high resistance not only at normal, but also at elevated temperatures.

Source: https://respect-kovka.com/kakoy-splav-nazyvaetsya-stalyu/

What is the difference between a metal and an alloy?

ALLOYS, materials having metallic properties and consisting of two or more chemical elements, at least one of which is a metal. Many metal alloys have one metal as a base with small additions of other elements.

The most common method of producing alloys is to solidify a homogeneous mixture of their molten components. There are other production methods, such as powder metallurgy. In principle, it is difficult to draw a clear boundary between metals and alloys, since even the purest metals contain “trace” impurities of other elements.

However, metal alloys are usually understood as materials obtained by purposefully adding other components to the base metal.

Almost all metals of industrial importance are used in the form of alloys ( see Tables 1, 2). For example, all smelted iron is almost entirely used for the production of ordinary and alloy steels, as well as cast irons. The fact is that by alloying with certain components the properties of many metals can be significantly improved.

If for pure aluminum the yield strength is only 35 MPa, then for aluminum containing 1.6% copper, 2.5% magnesium and 5.6% zinc, it can exceed 500 MPa. Electrical, magnetic and thermal properties can be similarly improved.

These improvements are determined by the alloy's structure—the distribution and structure of its crystals and the type of bonds between atoms in the crystals.

Many metals, say magnesium, are produced in high purity, so that you can accurately know the composition of the alloys made from it. The number of metal alloys used today is very large and is constantly growing. They are usually divided into two large categories: iron-based alloys and non-ferrous alloys. The most important alloys of industrial importance are listed below and their main areas of application are indicated.

Cast iron

Cast iron is an alloy of iron with 2–4% carbon. Silicon is also an important component of cast iron. A wide variety of very useful products can be cast from cast iron, such as manhole covers, pipeline fittings, and engine cylinder blocks. Properly executed castings achieve good mechanical properties of the material. See also BLACK METALS.

Copper alloys

These are mainly brass, i.e. copper alloys containing from 5 to 45% zinc. Brass containing 5 to 20% zinc is called red (tompak), and brass containing 20–36% Zn is called yellow (alpha brass).

Brasses are used in the production of various small parts where good machinability and formability are required. Alloys of copper with tin, silicon, aluminum or beryllium are called bronzes. For example, an alloy of copper and silicon is called silicon bronze.

Phosphor bronze (copper with 5% tin and trace amounts of phosphorus) has high strength and is used to make springs and membranes.

Lead alloys

Conventional solder (tertiary) is an alloy of approximately one part lead and two parts tin. It is widely used for connecting (soldering) pipelines and electrical wires. Antimony-lead alloys are used to make shells of telephone cables and battery plates. Alloys of lead with cadmium, tin and bismuth may have a melting point well below the boiling point of water (

70°C); They are used to make fusible plugs for valves in fire-fighting water supply sprinkler systems. Pewter, from which cutlery (forks, knives, plates) were previously cast, contains 85–90% tin (the rest is lead). Lead-based bearing alloys, called babbitts, typically contain tin, antimony and arsenic.

Light alloys

Modern industry needs high-strength light alloys with good high-temperature mechanical properties. The main metals of light alloys are aluminum, magnesium, titanium and beryllium. However, alloys based on aluminum and magnesium cannot be used at high temperatures and in aggressive environments.

Aluminum alloys

These include casting alloys (Al – Si), die-casting alloys (Al – Mg) and self-hardening high-strength alloys (Al – Cu). Aluminum alloys are economical, easily accessible, strong at low temperatures and easy to process (they are easily forged, stamped, suitable for deep drawing, drawing, extruding, casting, well welded and machined on metal-cutting machines).

Unfortunately, the mechanical properties of all aluminum alloys begin to deteriorate noticeably at temperatures above approximately 175 °C. But due to the formation of a protective oxide film, they exhibit good corrosion resistance in most common aggressive environments.

These alloys conduct electricity and heat well, are highly reflective, non-magnetic, harmless in contact with food (since the corrosion products are colorless, tasteless and non-toxic), explosion-proof (since they do not produce sparks) and absorb shock loads well.

Thanks to this combination of properties, aluminum alloys serve as good materials for lightweight pistons; they are used in carriage, automobile and aircraft construction, in the food industry, as architectural and finishing materials, in the production of lighting reflectors, technological and household cable ducts, and in the laying of high-voltage power lines.

The iron impurity, which is difficult to get rid of, increases the strength of aluminum at high temperatures, but reduces corrosion resistance and ductility at room temperature. Cobalt, chromium and manganese weaken the embrittling effect of iron and increase corrosion resistance.

When lithium is added to aluminum, the elastic modulus and strength increase, making the alloy very attractive to the aerospace industry.

Unfortunately, despite their excellent strength-to-weight ratio (specific strength), aluminum-lithium alloys have low ductility.

Magnesium alloys

Magnesium alloys are lightweight, characterized by high specific strength, as well as good casting properties and excellent cutting properties.

Therefore, they are used to make parts for rockets and aircraft engines, car body housings, wheels, gas tanks, portable tables, etc.

Some magnesium alloys, which have a high viscous damping coefficient, are used for the manufacture of moving machine parts and structural elements operating under conditions of unwanted vibrations.

Magnesium alloys are quite soft, have poor wear resistance and are not very ductile. They are easily formed at elevated temperatures, are suitable for arc, gas and resistance welding, and can also be joined by soldering (solder), bolts, rivets and adhesives. Such alloys are not particularly corrosion resistant to most acids, fresh and salt water, but are stable in air.

They are usually protected from corrosion by surface coating - chrome etching, dichromate treatment, anodizing. Magnesium alloys can also be given a shiny surface or clad with copper, nickel and chromium after being dipped into molten zinc. Anodizing magnesium alloys increases their surface hardness and abrasion resistance.

Magnesium is a chemically active metal, and therefore it is necessary to take measures to prevent the ignition of chips and welded parts made of magnesium alloys. See also WELDING.

Source: https://MyTooling.ru/instrumenty/chem-otlichaetsja-metall-ot-splava

What kind of steel is called boiling - Metalist's Handbook

Previously, we looked at the structure of steel (iron-carbon system), the deformation and destruction of metals, the influence of various impurities on its properties, etc.

In this publication we will consider types of steel according to the degree of deoxidation.

general information

So, steel is an alloy of Fe + C, (C – no more than 2%) + other elements. Steel is divided into carbon and alloy, taking into account the chemical composition, and based on the application - structural and instrumental . Special steels with specific characteristics are also produced for use in aggressive environments; such steels include heat-, corrosion-, and acid-resistant steels.

 The quality of steel is determined by the production method and the amount of bad impurities and is divided into ordinary, high-quality, enhanced and high quality.

Chemical composition of ordinary quality steels

There is a typification based on the nature of solidification in the mold and the geometric shape of the ingot (mold shape). There are calm, semi-calm and boiling .

Carbon steel

 Carbon steel is smelted without the addition of any alloying elements and is of ordinary and high quality.

Standard quality steels are usually divided into the following groups:

• group A – ensured by mechanical properties. Products made from steels of this group are used for subsequent welding, forging, etc. Moreover, the declared fur. properties may change. (St3, St5kp.).

• group B – steel is provided according to chemical requirements. composition. It is used for the manufacture of parts, during processing of which the mechanical characteristics determined by the composition may change.

Steel from group B is divided into 2 categories:

• 1st - the content of C, Si, Mn was established; limited content: S, P, N, As,
• 2nd - the amount of Cr, Ni, Cu is additionally limited.

 • group B - ensured by mechanical characteristics and content of chemical elements. Used in the production of welded parts.

Divided into six categories.

Group B is designated as follows: steel grade, degree of deoxidation, category number. 

 They have the same composition as steel of category 2, group B. 

Steel marking

Considering, as an example, the marking of steel St5ps (structural carbon steel of ordinary quality).

We determine that:

1.  this steel belongs to group A (since the category is indicated before the letters St (VSt1, VSt2), and only group A is not indicated).
2.  number 5 - determines the conditional number of the brand based on the chemical. composition and mechanical properties.
3.  ps is the degree of deoxidation.

If after the number defining the steel grade there is a letter G, then the steel contains a suspended amount of manganese. (St25G2S)

Degrees of steel deoxidation

 There are 3 degrees of steel deoxidation.

The deoxidation process allows you to restore iron oxide and bind dissolved oxygen, thus reducing its harmful effects.

Boiling steel

Boiling steel is not completely deoxidized. During casting into molds, it boils due to the abundant release of gas, so it is the most contaminated with gases and inhomogeneous. T.

The mechanical properties of the ingot may differ , since the distribution of chemical elements throughout the ingot is not uniform.

The head part of the ingot contains the largest amount of carbon and various bad impurities (such as sulfur or phosphorus), which requires removal of part of the ingot (5% of the total mass).

The accumulation of sulfur in certain areas can cause a crystallization crack to appear along the seam. In these areas, steel is less resistant to aging and is most brittle at sub-zero temperatures. silicon in boiling steel does not exceed 0.07%.

So, we can say about boiling steel that it is quite brittle, has poor weldability and is most susceptible to corrosion. Therefore, in order to improve the characteristics of steel, it is deoxidized with silicon (0.12-0.3%), aluminum (up to 0.1%) or manganese (deoxidation is also possible with other chemical elements that dynamically react with oxygen).

Boiling steel is quite brittle, has poor weldability and is most susceptible to corrosion. 

The deoxidation process allows you to restore iron oxide and bind dissolved oxygen, reduce its harmful effects, while maintaining a high temperature of the steel for a long time, which promotes maximum gas and slag removal, as well as obtaining a micro-grained structure due to the formation of crystallization areas. Due to the formation of these foci, the quality of steel improves.

  Liquation is the formation of a heterogeneous chemical structure of steel that occurs at the moment of crystallization. I distinguish two types of liquation: intracrystalline and dendritic. This phenomenon was first discovered by Russian metallurgists N.V. Kalakutsky and A.S. Lavrov in 1866.

Calm steel

The steel obtained as a result of deoxidation is called calm steel. silicon in mild steel is at least 0.12%, and the presence of non-metallic inclusions and slag is minimal.

Mild steel ingots have a dense, homogeneous structure and, accordingly, improved mechanical properties. Mild steel is excellent for welding and also has better resistance to impact loads. It is more homogeneous. It is suitable for the construction of supporting metal structures (due to its resistance to brittle fracture) that are subject to heavy loads.

Mild steel is excellent for welding and also has better impact resistance and is more uniform.

Semi-quiet steel

 Semi-quiet steel is intermediate in quality indicators.

It is semi-deoxidized and crystallizes without boiling, releasing a sufficient amount of gas and having fewer bubbles than boiling steel. Therefore, semi-quiet steel has average quality indicators (as close as possible to calm steel), and sometimes replaces calm steel.

The cost of semi-quiet steel is slightly lower than that of calm steel, and the yield of high-quality rolled products from such ingots is 8-10% better.

The quality indicators of semi-quiet became closer to calm.  

Semi-quiet steel hardens without boiling, but with the release of a large amount of gas. In such an ingot the content of bubbles is less than in a boiling ingot, but more than in a calm one.

 Since the production of boiling steel is cheaper than calm and semi-quiet steel, it is widely used for the production of the least critical rolled metal products, such as wire rod, strip, angle, and hardware.

: 11.03.2016

Source: https://ssk2121.com/kakuyu-stal-nazyvayut-kipyaschey/

Steel is the most common alloy in industry:

The durability and reliability of mechanisms depend on the material from which they were made, that is, on the totality of all its properties and features, which determine the performance characteristics. Today, most machine components and parts are made from various grades of steel. Let's look at this material in more detail.

What is steel

Steel is an alloy of two chemical elements: iron (Fe) and carbon (C), and the content of the latter should not exceed 2%. If there is more carbon, then this alloy belongs to cast iron.

But steel is not only a chemically pure compound of two elements; it contains both harmful impurities, such as sulfur and phosphorus, and special additives that impart the desired properties to the material - increase strength, improve workability, ductility, etc.

If the alloy contains less than 0.025% carbon and contains a small amount of impurities, then it is considered technical iron. This material differs from steel in all respects; it has high magnetic characteristics, and is used for the manufacture of electrical components. Pure iron does not exist in nature; it is very difficult to obtain it even in laboratory conditions.

Despite the fact that carbon is contained in a very small percentage, it has a significant impact on the mechanical and technical properties of the material.

An increase in this substance leads to an increase in hardness, strength increases, but at the same time ductility sharply decreases.

And, as a result, the technological characteristics change: with an increase in carbon, the casting properties decrease and the machinability deteriorates. At the same time, low-carbon steels are also difficult to cut.

Obtaining steel. Metallurgy

Steel is the most common alloy on the planet. It is produced industrially from cast iron, from which excess carbon and other impurities are burned off under the influence of high temperatures.

Steels are mainly produced in two ways: melting in open hearth furnaces and melting in electric furnaces. The material made in an electric furnace is called electric steel. It turns out to be cleaner in composition.

In addition, there are many special processes for producing alloys with special properties, such as vacuum arc melting or electron beam melting.

You can learn more about steels and other alloys by studying the science of metallurgy. It is considered one of the branches of physics and covers not only information about steel grades and their composition, but also contains information about the structure and properties of materials at the atomic and structural level.

Students of specialized universities take a special course “Industrial Steels”, where they examine in detail special-purpose alloys: construction, improveable, cemented, for cutting and measuring tools, magnetic, spring-spring, heat-resistant, steels for structures in cold climates, etc.

Classification of steels by quality

All steels are divided by quality into:

- ordinary quality steel;

- high quality;

— high quality steel;

- high quality.

The quality of steel directly depends on the percentage of harmful impurities (composition) and compliance with the declared mechanical and technological characteristics. All types are used in industry, but in different directions: steel of ordinary quality - for non-critical parts, steel of improved quality and high quality - in structures for which special requirements are imposed.

Steel according to GOST: classification

1. GOST 380-88. Ordinary quality carbon - St.1, St.2, St3ps, etc. Numbers from 0 to 6 indicate the grade; as the number increases, the carbon content increases. Letters ps, kp; cn – indices of the degree of deoxidation of the material: semi-calm, boiling, calm, respectively.
2. GOST1050-74. Carbon quality steel – 05; 08; 10; 20ps; 08 kp.

   Numbers up to 60 are the average C content in hundredths of a percent, letters ps, kp; sp – similar to step 1.

3. GOST 5632-72. High-alloy steels and alloys, corrosion-resistant, heat-resistant and heat-resistant – 30KhGSA, GN2; 50X; 20ХН3А. The first numbers are the carbon content: 30 – 0.3%; 40 - 0.4%; 45 - 0.45%, letters - the corresponding alloying element (X-chrome; G - manganese; T - titanium; A-nitrogen, etc.

   ), the number behind the letter is the percentage of the alloying element. If there is no number, then the proportion of the substance is 1.5%, the letter A at the end means that it is high-quality steel. This applies to both tool and alloy steels.

4. GOST1435-74. Carbon instrumental - U7, U8, U10A. Explanation: U7 – 0.7% C; U8 – 0.8% C; U – carbon; A - high quality.
5. GOST5950-73.

   Alloyed instrumental – 5ХГН; X12; 8X3, etc. The decoding of the brand is similar to point 3, but the C content is indicated in tenths of a percent. If carbon is less than 0.1%, then the numbers are not indicated - XB4; CHC; CHV, etc.

6. GOST801-78. Bearing – ШХ4; ШХ15; SHH15SG. ШХ – bearing, number – chromium content: ШХ4 – 0.4% chromium, ШХ15 – 1.5% chromium, other letters and numbers – content of additional alloying elements.
7. GOST 1414-75.

   Structural grades with increased and high cutting machinability - A12, A20, A30, A40G. Decoding of carbon content: A20 - 0.2% C, A12 - 0.12% C, A30 - 0.3% C.

Steel. Properties: tables for the most common brands with basic mechanical and technological characteristics

steel grade	Mechanical properties	Technological properties
σt, MPa	σв, MPa	δ, %	Machinability	Weldability	Plasticity during cold working
40X	786	980	10	IN	U	U
45G	372	569	15	U	N	N
25ХГТ	1080	1470	10	U	N	U
40ХС	1080	1225	12	U	N	N
30HMFA	932	1030	13	IN	N	U
ШХ15	410	715	21	U	N	U
12Х13	415	588	20	U	N	IN
A20hot rolled	510	600	15	IN	—	—

N - low;

U - satisfactory;

B – high;

σт – physical yield strength, MPa;

σв – tensile strength, MPa;

δ – relative elongation, %.

Source: https://www.syl.ru/article/205882/new_stal---eto-samyiy-rasprostranennyiy-splav-v-promyishlennosti

Difference between metal and steel

Metals are substances that have unique properties such as excellent electrical and thermal conductivity, light reflectivity, ductility and ductility. Sometimes the term metal is used to refer to chemical elements in group 1, group 2, and block d of the periodic table. It is also a general term used to refer to metal or metal alloys.

Steel is a metal alloy consisting of iron, carbon and some other chemical components. There are different types of steel manufactured to achieve the desired properties.

The main difference between metal and steel is that the term metal can be used to refer to a chemical element or substance with characteristic metallic properties, while the term steel is used to refer to a metal alloy consisting of iron, carbon and some other elements.

Key areas covered

1. What is metal
- definition, properties of metal
2. What is steel
- definition, different types
3. What is the difference between metal and steel
- Comparison of the main differences

Key words: corrosion, ductility, electrical conductivity, ductility, metal, metal alloy, light reflectivity, steel

What is metal

The term metal can be used to refer to a chemical element or substance with characteristic metallic properties. In general, we call substances with high strength, high electrical and thermal conductivity and high metal ductility.

Group 1 and group 2 elements in the periodic table of elements are known as metals. Group 1 elements are called alkali metals, and group 2 elements are known as alkaline earth metals. These elements can form cations by removing valence electrons. Additionally, d-block elements are also considered metals.

Substances made from these elements are known as metals. These metals have unique properties known as metallic properties. Some basic properties of metals are listed below.

• Metallic appearance (shine due to high light reflectivity)
• Very high melting and boiling points
• High density
• Excellent thermal and electrical conductivity
• stringiness
• stringiness

Figure 1: Gold is a metal

Metals and their applications

Some common useful metals are given in the following table with some of their uses.

metal	Applications
Iron (Fe)	Purpose of construction
Gold (Au)	Jewelry
Copper (Cu)	Electrical conductivity wires, statues, coins
Magnesium (Mg)	Car seats, laptops, cameras, etc.

Definition

Metal: Metal refers to a chemical element or substance with characteristic metallic properties.

Steel: Steel is a metal alloy consisting of iron, carbon and several other elements such as manganese, tungsten, phosphorus and sulfur.

Nature

Metal: A metal is either a chemical substance or a chemical element.

Steel: Steel is a metal alloy.

corrosion

Metal: All metals can corrode.

Steel: Steel can corrode (except stainless steel).

Weight

Metal: Some metals are light in weight (like magnesium), but some are heavy in weight (like iron).

Steel: Steel is a heavy metal.

Melting temperature

Metal: Some metals have lower melting points than steel.

Steel: Steel has a fairly high melting point.

Conclusion

Metals and metal alloys are very useful substances in construction. Steel is a metal alloy. The main difference between metal and steel is that the term metal can be used to refer to a chemical element or substance with characteristic metallic properties, while the term steel is used to refer to a metal alloy consisting of iron, carbon and some other elements.

Recommendations:

1. Helmenstine, Anne Marie. “What properties make metals unique?” ThoughtCo,

Source: https://ru.strephonsays.com/difference-between-metal-and-steel

Steel: composition, properties, types and applications. Stainless steel composition

Many people know that steel is a product obtained by melting other elements. But which ones? What does steel contain? Today, this substance is a deformable alloy of iron and carbon (its amount is 2.14%), as well as a small proportion of other elements.

Classification

The material we are considering can be classified according to several indicators:

• The first indicator is the chemical composition of the steel.
• The second is the microstructure, which is also very important.
• Of course, steel differs in its quality and method of production.
• Also, each type of steel has its own application.

The composition can be considered in more detail using the example of chemical composition. Based on this feature, two more types are distinguished - alloy and carbon steels.

Among carbon steels, there are three varieties, the main difference of which is the quantitative carbon content. If the substance contains less than 0.3% carbon, then it is classified as low-carbon. of this substance in the region of 0.3% to 0.7% transfers the final product to the category of medium-carbon steels. If the alloy contains more than 0.7% carbon, then the steel belongs to the high-carbon category.

With alloy steels the situation is approximately the same. If the material contains less than 2.5% of alloying elements, then it is considered low-alloyed, from 2.5% to 10% - medium-alloyed, and from 10% and above - highly alloyed.