The achievements of domestic science in metallurgy and metalworking constitute a reliable foundation for large-scale modernization of industry.
Justifying the need for accelerated industrialization of the country, Stalin said in 1931: “We are 50-100 years behind the advanced countries. We must cover this distance in ten years. Either we do this, or we will be crushed.”
Industrialization was aimed at creating powerful and most modern metallurgy. After all, metal, especially high-quality steel, is the basis of any production.
It would be wrong to say that advanced Soviet metallurgy was created from scratch. Ural factories once supplied cast iron and steel to the whole of Europe. Sabers made of Zlatoust steel were not inferior to the famous damask ones. Chrysostom was compared to Solingen. And at the turn of the 19th and 20th centuries, modern South Russian metallurgy arose on the basis of high-quality Krivoy Rog iron ore and the best Donetsk coal in the world.
Russian metallurgical science and invention had something to be proud of. Speaking about the scientific and technical achievements of our country, we need to remember Polzunov, who back in the 18th century was the first in the world to build a blast furnace blower driven by steam power. It is necessary to say about Anosov, who created the metallurgy of alloy steels, about Chernov, who founded the science of metallurgy and developed the theory and technology heat treatment metals It is necessary to name Sobolevsky, who created powder metallurgy, in which Russia later became so successful, and the Goryainov brothers, who developed and introduced into production the advanced technology of open-hearth smelting on liquid cast iron. The list could be expanded.
In just a few years of industrialization, the selfless labor of the Soviet people erected gigantic and most modern metallurgical plants at that time - Magnitogorsk, Kuznetsk, and the Chelyabinsk Alloy Steel Plant was built.
Alloy steels were given special importance. This was justified a hundredfold during the Second World War.
* The famous "thirty-four" - the Soviet medium tank T-34, generally recognized as the best tank of the war - had exceptional maneuverability. Maneuverability was explained by the fact that the “thirty-four” was much lighter in weight than German combat vehicles. The armor of the Soviet tank was thinner, but at the same time much stronger - due to alloy steel.
* Alloy armor saved the lives of thousands and thousands of tankers. The armor of German tanks was cracking when hit by shells - there was a shortage of alloying metals in the steel. In the armor of the "thirty-four" the shell only left a dent - the steel was "soft" precisely thanks to the alloying metals.
After the war, the metallurgy of the USSR continued to develop rapidly. Already with an emphasis on the quality side. One after another, factories of all kinds of special steels and alloys came into operation. Especially titanium ones, which have exceptional strength. The metallurgy of Soviet Russia took the lead and is still not losing ground.
After the war, the USSR became a world leader in the development of advanced technologies in metallurgy. The base for scientific research and development in the industry was the Novotulsky Metallurgical Plant.
* Fact. Of the 13 largest innovations in metallurgy of the post-war period, 8 belonged to the USSR.
* Fact. Scientists and engineers at the Novotulsky plant developed and introduced into production the technology of continuous casting of steel, which revolutionized the steel industry. Today, over 90% of all steel in the world is produced using this technology.
* Fact. In Japan, the so-called self-hardening molding mixtures invented by Soviet socialists were called a “revolution in foundry production.” A fundamentally new technology has improved the quality of castings by an order of magnitude, which has sharply increased labor productivity. In addition, the innovation minimized manual labor, noise and dust in foundries.
* Fact. It was in the USSR that oxygen injection methods were first used in blast furnaces, converter furnaces, and electric furnaces. They, too, are generally recognized by experts, revolutionized metallurgical production.
RUSSIAN PATENTS AND LICENSES
Among the Soviet priorities, John Kaiser, US President Reagan's adviser on science and technology, named "metal and materials processing technologies."
The list of the largest Russian scientific and technical achievements includes the heat treatment of metals, in which our outstanding metallurgist Chernov succeeded. He led his Scientific research and development work in the first half of the 19th century. Chernov's work was continued by a galaxy of his talented students. Russian "thermists" excelled in their field.
But Russia began to achieve fundamental success in metalworking later - when its modern machine-building plants In Petersburg, Nizhny Novgorod, Bryansk, others industrial centers. At these factories, the ingenuity inherent in Russian craftsmen was combined with modern European equipment and technology.
In the USSR, the fleet of metalworking equipment became the largest in the world. The factories of the Ivanovo Machine Tool Association produced high-precision computer-controlled metalworking machines, which were in exceptional demand on the world market. Foreign customers stood in line behind them.
Russia is a recognized leader in the production of heavy metalworking equipment. In Japan, the USA, Germany, France, England, Italy and other countries, for example, there are giant rotary lathes manufactured by the Kolomna Heavy Engineering Plant. These 20-meter machines process hundreds of tons of workpieces with micron precision.
Russia was especially successful in the manufacture of heavy presses. Perhaps, in this area it has no serious competitors at all. One specific example. In 1977, a giant hydraulic press with a force of 65 thousand tons was delivered from the USSR to France. French specialists and engineers speak about the Russian press in the most flattering way. Almost half a century has passed, and this press remains the most powerful in Europe.
And recently, in 1999, Russia supplied a heavy press to the United States. Its force is much less - 15 thousand tons. Nevertheless, he also amazed the Americans with his power. They nicknamed him "Big Bear".
The field of processing metals and other materials is extremely wide and multifaceted. And the further high technologies develop, in particular in electronics, the more important the miniaturization of processing becomes for industry.
Among the largest scientific and technical achievements of Russia is one of the great discoveries of our time -.
revolutionized the processing of metals and materials. Just one fact. Laser drilling of diamonds reduces processing time from 48 hours to... 2 minutes, i.e. 1500 times!
Among Russia's scientific and technical achievements are a number of discoveries in physics and chemistry. It would seem how they can be connected purely theoretical work in Nuclear Physics with Industrial Practice. But life again and again confirms the paradoxical thought: there is nothing more practical than a good theory.
The priority research of our scientists in the field of plasma physics naturally led to the development of industrial technologies for plasma processing of metals and materials. In this area, the USSR and Russia also achieved impressive results.
Russia is still a leader in the field of plasma metal processing. To consolidate leadership, a special inter-industry scientific and technical complex was created, and a program for the accelerated introduction of plasma technologies into industry was developed. The main thing is that they built a powerful plant for the production of plasma equipment.
Successes were not slow to appear. For example, at the Elektrostal Heavy Engineering Plant, the processing of all large and critical parts has long been associated with plasma technology. Economic effect turned out to be huge. The quality of processing has improved by an order of magnitude. A lot of electricity, high-grade steel, and most importantly, human labor are saved.
The long-standing recognition by John Kaiser, Advisor to the President of the United States, of our country's leadership in the processing of metals and materials was later confirmed a hundredfold by other foreign reviews. In particular, reviews from the USA.
The American company "Multi Ark" at one time acquired the right to produce the Soviet vacuum-plasma installation "Bulat" for hardening the coating of tools. Company executives gave the following assessment of the installation: “This is not just an improvement. This is a technological revolution. This is technology tomorrow for today's industry."
There are many similar examples. And today the potential of the Russian economy remains very high. Russia has the largest “portfolio of ideas” that determine development high technology and the most advanced technology, they will become in demand when real industrial modernization begins in the country.
Metallurgy today, like 30 years ago, is divided conditionally according to its purpose into two groups: the first works for mass production, the second is special metallurgy. Accordingly, materials are divided into those for which there is no requirement special requirements except the price. And those for which special characteristics are very important. One of the main tasks of special materials is not to be structural in the traditional sense, since their load-bearing capacity is not very important, but to be a part or basis for a resource product.
The functional characteristics of steel materials are largely based on the coatings that are applied to them. They impart new properties to materials - heat resistance and tribological qualities.
Another one important feature modern metallurgy is that it should serve as the basis for recycling, that is, it is necessary to take into account all life cycle materials. Today, more complex and expensive ore bases are used as raw materials than before. Therefore, it is necessary to involve in processing other sources of resources that have been recovered from non-traditional raw materials, primarily secondary ones. At the same time, the quality requirements for materials obtained from recycled materials remain very high.
One of the main trends in modern metallurgy is the struggle for the “purity” of the material - the removal of coarse contaminants and harmful impurities, and the elimination of the appearance of cracks during operation. Introduced in the late 1970s and early 1980s, the term “clean steel” disappeared for a while, but is now reappearing. But if earlier we talked about inclusion sizes of 20-40 microns, now it is no more than 2-3 microns, and more often than not, a zero level of contamination. As a result, even traditional alloys become new in their performance properties.
The classic modern metal material has two main characteristics. First, it is a structural material that is predictable both in its properties and in its cost, which can be controlled. Economic considerations, of course, indicate that the metal is not losing its position.
Over the past few years, metal processing technology has undergone two subtle revolutions. One of them was based on the advent of five-axis machines and carbide tools based on tungsten carbide. The second is associated with the emergence of so-called additive technologies, based on completely new principles for metallurgy. Five-axis machines have become commonplace today. And here additive technologies will manifest themselves in the next three to five years.
And this significantly changes traditional metallurgy. One can imagine that many high-quality products and high-quality materials may change their form of existence - they will mainly be produced in powder form. And the parts will be made from them using a virtually direct method. Confirmation of the seriousness of such trends is the information published a few days ago that General Electric is going to invest $1.4 billion in the merger famous companies, specializing in 3D printing: Swedish Arcam AB and German SLM Solutions Group AG. The stated goal of the association is to begin producing products for the engine and energy industries based on 3D technologies. There is no doubt that this will greatly shake up the market and give additional impetus to the development of these technologies.
Scientists are developing materials that can operate in extreme temperatures
When talking about new materials, one cannot fail to mention polymers. Carbon fiber has long been known: the body of the Boeing 787 aircraft is made entirely of this material. In products that require both good mechanical properties and lightness, of course, such materials will replace metals, especially if they are used in extreme conditions. But now the interpenetration of metal and polymer in structural materials is so strong that it is already difficult to say what it really is: in terms of thickness it is a polymer, in terms of properties it is a polymer on metal.
Today the industry operates in several directions. The first is the development of materials that can operate in extreme temperatures. Secondly, important work is going on to extend the life of materials that can be guaranteed to last 100 years. This is relevant, for example, for nuclear power. Also, many companies and research teams are developing biocompatible materials and especially composites, since we have already learned to combine metals with non-metals and obtain new durable materials. They are required by modern medicine for the production of implantable devices, prosthetics, etc.
By the way
A material has been created that is not inferior in strength to metal, and at the same time is 100 times lighter than expanded polystyrene. The material, known as "microgrid", was developed by scientists from HRL Laboratories (USA), which is owned by Boeing and General Motors. It is 99.9 percent air and is organized into a network of tiny hollow tubes. The thickness of their walls is only 100 nanometers - 1000 times thinner than a human hair. The video shown by the developers shows that a fragment of the microlattice lies on a pubescent dandelion, without crushing it.
The microlattice was made from the well-known metal nickel-phosphorus, but with an unusual architecture and using an innovative manufacturing process based on the principle of 3D printing. This technology has great prospects in aircraft construction, creation spaceships and in other areas of production where ultra-light, but at the same time very durable materials are required. The properties of the microlattice are based on the same principles that made it possible to create the Eiffel Tower - a structure 324 meters high, but incredibly light. And Eiffel and his engineers, as you know, applied knowledge of how human bones are structured in their masterpiece. Modern technologies made it possible to translate the same principles onto a very small scale.
Today, rolled metal is the mainstay of a huge number of industries. Reinforcement, channel, sheet steel, angle - all this is absolutely indispensable in construction, automotive industry, furniture and door production. If you spend a little time and try to compile a list of areas where rolled metal products are used, it becomes clear that this list is actually endless.
Accordingly, it is not surprising that the metalworking industry is trying in every possible way to introduce the achievements of science and technology into the metal processing process in order to speed up and improve production. This also applies to metal cutting. For example, if your company manufactures metal structures, then it is not enough to just buy reinforcement; often it needs to be cut correctly. The most common machines for such cutting are lathes and milling machines. However, recently laser technologies have become increasingly popular.
Laser machines allow you not only to obtain a high-quality cut, but also to produce a part of a very complex shape. This becomes possible because the process is controlled through a computer system. As a result, the stages of “finishing” the part and finishing are eliminated, which overall reduces the cost of production.
Another advantage of laser cutting is the ability to work with volumetric or sheet workpieces. For example, cutting pipes refers to volumetric workpieces. And what’s most important is that you can make as many parts as you like, and they will all be identical appearance, and in size.
Of course, laser machines also differ in their parameters, characteristics and power. This is quite justified, since the sale of rolled metal products also varies in intensity and range. If a company sells only sheet steel, then there is no point in purchasing a laser machine for volumetric cutting at an increased price. It is much more efficient to purchase a machine for laser sheet cutting, on the one hand, saving money, and on the other, significantly expanding the range of services for customers.
Today, laser technology makes it possible to quickly obtain the required number of parts at quite adequate costs for their production. And since control occurs at the computer level, only one specialist monitoring the process is enough.
General information. Ferrous and non-ferrous metals. Basic metallurgical processes.
Metallurgy
General information about metals and alloys
Metals are crystalline substances whose characteristic properties are high strength, ductility, thermal and electrical conductivity, and a special luster called metallic. The properties of metals are determined by the presence of a large number of moving electrons in their crystal lattice. Metals make up about 75% of the elements of D.I. Mendeleev’s periodic table.
Typically, metals are not used for pure form, but in the form of alloys.
Metal alloys are substances formed as a result of the solidification of liquid melts consisting of two or more components. The components that form an alloy include chemically individual substances or their stable compounds. Metal alloys consist either only of metals (for example, an alloy of copper and zinc - brass), or of metals with a small content of non-metals (alloys of iron and carbon - cast iron and steel). By changing the components and the relationships between them, alloys with a wide variety of physical, mechanical or chemical properties. After solidification, solid solutions, chemical compounds or mechanical mixtures can form in the alloy composition.
Solid solutions arise as a result of the penetration of atoms of another metal or non-metal (soluble component) into the crystal lattice of the base metal (solvent). Based on the type of arrangement of the atoms of the soluble component in the crystal lattice of the solvent, substitutional and interstitial solid solutions are distinguished.
A substitutional solid solution occurs as a result of the replacement of part of the atoms in the crystal lattice of the base metal with atoms of the soluble component. Examples of substitutional solid solutions are alloys of copper with nickel, iron with nickel, chromium, silicon, and manganese.
In an interstitial solid solution, the atoms of the dissolved component are located in the free spaces between the atoms of the base metal. Typically, an interstitial solid solution occurs in a system consisting of a metal and a nonmetal, for example, in an alloy of iron and carbon. When solid solutions of metals are formed, the strength, hardness and electrical resistance, but ductility decreases in comparison with the base metal. Solid solutions form the basis of technical alloys: structural, stainless and acid-resistant steels, brasses, bronzes.
Chemical compounds are formed at a strictly defined quantitative ratio of components. Chemical compounds include, for example, iron carbide (cementite), which is part of iron-carbon alloys:
3Fe + C = Fe3C.
Cementite has high strength and hardness, but is very fragile. Chemical compounds of metal with metal are called intermetallic. This includes, for example, compounds of aluminum with copper CuAl2, magnesium with zinc MgZn2, etc. Intermetallic compounds most often do not obey the rule of normal valency. The presence of chemical compounds strengthens the alloys, but at the same time reduces their ductility.
Mechanical mixtures arise as a result of the accretion of crystals of components that simultaneously precipitate from the liquid melt as it cools. In the crystals that make up the mechanical mixture, the crystal lattice of the original alloy components is preserved. Thus, each of the components retains its specific properties. Mechanical mixtures can consist of pure components, solid solutions or chemical compounds.
All metals and alloys are divided into ferrous and non-ferrous.
Ferrous and non-ferrous metals
Cast iron contains carbon from 2 to 4.3%; in special cast irons (ferroalloys) the amount of carbon can reach 5% or more.
Pig iron is smelted in blast furnaces from iron ores. Iron ores are a natural mixture of iron oxides and a mineral component called gangue (silica, alumina). In the process of smelting ore, iron is reduced from oxides, freed from harmful impurities and separated from waste rock.
Depending on the composition and purpose, cast iron obtained from blast furnace is divided into gray, white and malleable.
Gray, or foundry, cast iron is obtained as a result of the slow cooling of liquid cast iron with a significant content of carbon and silicon in the ore. This type of cast iron has from 1.7 to 4.2% carbon and up to 4.25% silicon. Gray cast iron fills molds well and is easy to process with cutting tools. After cast iron is melted in a furnace, it is suitable for pouring into pre-prepared molds.
In gray cast iron, carbon is in a free state in the form of graphite flakes. This structure of cast iron gives it a gray color at fracture points.
White, or pig iron, contains up to 4.5% carbon. Depending on the production method, the following additives are added to cast iron; silicon, manganese, phosphorus, sulfur. This type of cast iron is obtained by quickly cooling liquid cast iron. Carbon is found in white cast iron in a bound state in the form of cementite. In places of fracture, cast iron has White color. White cast iron is hard and brittle; it is used mainly as a raw material for steel production.
Ductile iron contains 2 to 2.2% carbon. It is made from white cast iron. The castings are placed in steel boxes with clean sand and simmered in ovens, that is, they are subjected to prolonged heating and then slowly cooled.
Steel (GOST 5157-53) contains carbon up to 2%. Steel has high mechanical properties and technological properties.
Steel is made from cast iron different ways. Regardless of the method, the essence of the steelmaking process is the oxidation of undesirable impurities contained in cast iron and the reduction of its content of carbon, silicon, manganese, phosphorus, and sulfur.
The Bessemer converter method of producing steel from cast iron is carried out in a converter.
In the converter, compressed air is blown through the thickness of the cast iron. atmospheric air at a pressure of up to 2.5 kgf/cm2, as a result of which carbon is burned out and cast iron turns into steel. The heat released in this case increases the temperature of the metal to 1600 ° C. Recently, in many metallurgical plants, air enriched with oxygen or pure oxygen is blown through cast iron in converters. This improves the quality of the steel produced.
The open-hearth process for producing steel from cast iron is as follows. Solid or molten cast iron with the addition of scrap1 or ore is smelted on the hearth of an open-hearth furnace. The required temperature is created due to the combustion of the heated mixture gaseous fuel and air.
The purpose of the open-hearth process is to remove (burn out) from the molten metal those elements that should not be in the finished steel and that enter the molten metal from the charge or from the gaseous environment, as well as to reduce the content of those elements to the required standard elements that are a necessary component of steel. If necessary, the process is completed by introducing alloying elements into the steel.
Open hearth steel is of higher quality than converter steel, but the converter method is more productive.
The electric melting method for producing steel is the most advanced in comparison with the methods described above. In terms of the essence of the processes occurring, the electric melting method does not differ from the open-hearth method. But electric melting makes it possible to obtain high-quality steel and simplify the smelting process. The widespread use of this method is still limited by the high cost of electricity.
According to the chemical composition, steels are divided into carbon and alloy; both of these types of steel are used in construction. Carbon steels include: machine-building (structural) steel with a manganese content of up to 1.1% with a carbon content of up to 0.75%, tool steel with a reduced manganese content (up to 0.4%) with a carbon content above 0.6%. Alloy steels are low alloyed with an alloying element content of no more than 2.5%, medium alloyed with a total alloying element content from 2.5 to 5.5%, high alloyed with a total alloying element content of more than 5.5%.
Depending on the purpose, steel has four classes: construction - used in the form of rolled products without heat treatment for the structures of bridges, buildings, cars, etc.; mechanical engineering - used for the manufacture of machine parts; instrumental—for the manufacture of various metal-cutting and other tools; special purpose— stainless, acid-resistant, heat-resistant, scale-resistant, etc.
Ferrous metals include iron and alloys based on it - steel and cast iron. Ferrous metals account for about 95% of the world's metal products. In order to impart specific properties to ferrous metals, improving or alloying additives (nickel, chromium, copper, etc.) are introduced into their composition. Ferrous metals, depending on their carbon content, are divided into steel and cast iron.
Steel is a malleable iron-carbon alloy with a carbon content of up to 2%. It is one of the main structural building materials. Steel is used to make building structures, pipelines, and reinforced concrete fittings.
According to the method of production, hoists are divided into open-hearth, converter and electric steels. According to the chemical composition, depending on the chemical elements included in the alloy, steels are classified as carbon and alloyed.
Carbon steel, along with iron and carbon, contains up to 1% manganese, up to 0.4% silicon, as well as impurities of sulfur and phosphorus. If the amount of impurities does not exceed a specified upper limit, they are called normal.
Cast iron is an iron-carbon alloy with a carbon content of 2...4.3%. It also contains manganese, sulfur, and silicon phosphorus. The bulk of pig iron is used for steel production. In addition, it is used as an independent structural material. Depending on the form of carbon bonding, white and gray cast iron are distinguished.
White cast iron contains carbon in a chemically bonded state in the form of iron carbide Fe3C.
In gray cast iron, carbon is in a free state in the form of graphite.
Ferrous metallurgy
The heavy industry sector, which includes a complex of interrelated sub-sectors: metallurgical production itself (blast furnace, steelmaking, rolling), pipe and hardware production, mining, beneficiation and agglomeration of ore raw materials, coke production, production of ferroalloys and refractories, extraction of non-metallic raw materials for ferrous metallurgy and secondary processing of ferrous materials. metals The most important types of ferrous metallurgy products: hot-rolled and cold-rolled steel, steel pipes and metal products.
Ferrous metallurgy is the basis for the development of most industries National economy. Despite the rapid growth of production chemical industry, non-ferrous metallurgy, building materials industry, ferrous metals remain the main structural material in mechanical engineering and construction. So, specific gravity Ferrous metals in the total volume of structural materials consumed by the leading branches of mechanical engineering of the USSR exceeded 96% in 1976. The industry consumes approximately 20% of the country's fuel and energy resources.
For thousands of years, the development of human society has been inextricably linked with the use of iron as the main material for the manufacture of tools. V.I. Lenin called iron one of the foundations of civilization, one of the main products of modern industry.
Iron production in Russia has been known since ancient times. Iron ores were first smelted in cheese furnaces, then (from about the 9th century) in special above-ground furnaces blown by hand bellows. Factory production of cast iron and iron began in 1632–37, when the first plant with a blast furnace that smelted up to 120 pounds of cast iron per day was built near Tula. In 1700, about 150 thousand pounds of pig iron were smelted. Having increased during the first quarter of the 18th century. its smelting increased 5 times, Russia took first place in the world in the production of ferrous metals and until the beginning of the 19th century. held him. However, in subsequent years, the growth rate of iron and steel decreased, and by 1913 the country occupied only 5th place in the world, and its share in the world production of iron and steel was 5.3%.
Industrial steel production technology
Iron is one of the most common elements in nature. The earth's crust contains about 5%. However, it is not found in its pure form, as it easily combines with oxygen to form oxides. The most famous iron ores from which iron is obtained are magnetite FeeCU (containing more than 70% iron), hematite Fe3C>3 (30-50%), limonite FeO(OH), etc. Along with pure iron, the ore contains carbon, other metals, as well as harmful impurities - sulfur, phosphorus, nitrogen, etc.
The primary product obtained from ore is cast iron (an alloy of iron and carbon). Cast iron is produced in blast furnaces by smelting iron ore at T=1600°C with the addition of coke and limestone; In the process of burning coke, iron is reduced, while at the same time limestone is intended to more easily separate non-metallic impurities along with the slag. Molten cast iron as heavier component It is collected at the bottom of the furnace and then released into special molds. The resulting gray cast iron with a coarse-grained structure with a 4% carbon content is used for casting, white cast iron with a fine-grained structure is used for steel production.
Steel is an alloy of iron and carbon, the percentage of which, due to special processing (alloying), is reduced to an amount not exceeding 1.2%. In modern metallurgy, three methods are used to produce steel from cast iron: Open-hearth, Bessemer and Thomas. The main raw materials for producing steel are white cast iron, scrap metal and waste (steel scrap), as well as additives in the form of silicon, manganese, chromium, nickel, copper, etc. to obtain steel grades with predetermined properties.
The most common way to obtain construction steels— open-hearth.
This method consists in the fact that molten cast iron, placed in a special furnace lined with refractories, is supplied with a continuous stream of air with hot gas maintaining t = 2000 ° C. Under the influence of this temperature, carbon is burned from the molten mass within 4-12 hours (depending on the required quality of steel), the percentage of which is strictly controlled.
The oxygen-converter method of producing steel, which has recently become increasingly widespread in world practice, consists of blowing a hot mixture of air and oxygen under pressure through molten cast iron. As a result, carbon and harmful impurities burn in the molten cast iron. Depending on the composition of the internal refractory lining of the converter, the method is called Bessemer (acid lining) or Thomas (basic lining). The Thomas method of steel smelting does not guarantee the required qualities, therefore this steel is not used for building structures in the country.
The highest quality multi-alloy steels are produced in special electric furnaces. The maximum temperature of about 2200 °C is achieved using an electric arc that occurs between two carbon electrodes. The advantage of this method is that harmful elements from air and gas do not reach the molten metal, as is the case in the first two methods. Steel obtained by any method is cast into special molds and sent in this form for further processing to produce rolled products, castings and other products.
Non-ferrous metals. Nonferrous (non-ferrous) metals include all metals except iron. Most often, metals and alloys based on aluminum, copper, zinc and titanium are used in construction.
Metals are very technological: firstly, products from them can be produced by various industrial methods (rolling, drawing, stamping, etc.), secondly, metal products and structures are easily connected to each other using bolts, rivets and welding.
However, from a builder's point of view, metals also have disadvantages. The high thermal conductivity of metals requires thermal insulation of metal structures of buildings. Although metals are non-flammable, metal structures of buildings must be specially protected from fire. This is explained by the fact that when heated, the strength of metals sharply decreases and metal structures lose stability and deform. Corrosion of metals causes great damage to the national economy. And finally, metals are widely used in other industries, so their use in construction must be economically justified.
Metallurgy (from the Greek "metallon" - "mine", "metal" and "ergon" - "work") - in the original, narrow meaning of "the art of smelting metals from ores." In its modern meaning, it is a field of science and technology and a branch of industry that covers all processes for producing metals and alloys and giving them certain forms and properties.
Historically, metallurgy has been divided into non-ferrous and ferrous. Ferrous metallurgy includes iron-based alloys - cast iron, steel, ferroalloys (ferrous metals account for about 95% of all metal products produced in the world). Non-ferrous metallurgy includes the production of most other metals. In addition, metallurgical processes are also used to produce non-metals and semiconductors (silicon, germanium, selenium, tellurium, etc.). In general, modern metallurgy covers the processes of producing almost all elements of the periodic table, with the exception of halogens and gases.
The science of metals, metallurgy, is rapidly developing, the foundations of which were laid by Russian scientists P. P. Anosov and D. K. Chernov. Metal scientists understand the structure of metals, find ways to improve their properties, create new alloys that allow designers to develop fundamentally new machines - especially light, especially strong, etc.
The basis of modern iron and steel industry is made up of factories, each of which is the size of a small city in terms of territory and number of employees. The metal passes through a complex path here. First, ore is enriched at mining and processing plants (GOK), then at ferrous metallurgy plants it is roasted, turning it into agglomerate or pellets. Pig iron is smelted from them in blast furnaces. The cast iron then goes to the steel shop, where it is melted into steel in open hearth furnaces, oxygen converters, or electric furnaces (see Electrometallurgy). Steel ingots are transported to rolling shops, where they are used to make metal products: rails, beams, sheets, pipes, wire (see Rolling, rolling mill). Between the workshops there are rails on which people walk trains, delivering ore and liquid iron, steel ingots and finished rolled products.
The same, and in some cases even more complex, path is followed by metals at non-ferrous metallurgy plants. Technological process The production of some non-ferrous metals involves dozens of operations.
What does the future hold for metallurgy? Will humanity really have to constantly build giant factories to satisfy its needs for metal? After all, we should not forget that metallurgy mainly deals with fire: in order to melt ore or steel, they must be heated to a high temperature. And pyrometallurgy (this is the name of the branch of metallurgy that uses heating of metal: from the Greek word “pyre” - “fire”) burns oxygen in the air, pollutes the atmosphere with combustion waste, and wastes a lot of fresh water on cooling units. In short, it harms nature. Therefore, scientists have developed new ways to develop metallurgy. This is, first of all, the direct reduction of iron from ore, bypassing the blast furnace process. Direct reduction plants, which are fully automated and tightly sealed, will smelt ore into metal ingots or pure iron powder. And then the ingots or powder, packaged in containers, will be delivered to machine-building factories, where they will be used to make products either by the conventional method or by powder metallurgy. These factories do not have to be as huge as the existing ones. On the contrary, they will be small and, as scientists suggest, sometimes mobile, that is, mobile. They will be transported by barges or by helicopter to small ore deposits, the development of which is currently considered unprofitable. Mini-plants, fully automated, will make the development of these deposits economically feasible.
Electrometallurgy is developing rapidly, and electricity is increasingly used in all subsequent stages of metal processing. Next in line is the creation of fully automated metallurgical production, controlled by a computer—automatic metallurgical workshops.
Metal corrosion
The processes of destruction of materials caused by the action of various chemicals on them are called corrosion. Chemicals that destroy Construction Materials, are called aggressive. An aggressive environment can be atmospheric air, water, various solutions of chemicals, and gases.
Atmospheric corrosion occurs under normal atmospheric conditions through the interaction of air oxygen, moisture and metal. Products with a large surface area, such as roofs, metal trusses, rafters, and bridges, are subject to this corrosion.
Various structures located in water are subject to underwater corrosion, and the process is enhanced by the presence of even a small amount of acids or salts in the water.
Soil corrosion occurs when soil interacts with the metal of water and sewer lines. Corrosion increases with the presence of salts in soil water and fluctuations in groundwater levels.
Depending on the nature of the aggressive environment, metal corrosion can occur chemically and electrochemically.
The chemical corrosion process occurs when metals are exposed to dry gases at high temperatures or liquid non-electrolytes (liquids that do not conduct electric current). Chemical corrosion also includes the destruction of metal by oxygen in dry air and other gases (carbon dioxide, sulfur dioxide).
The electrochemical corrosion process is caused by the action of electrolytes on the metal - liquids that carry electric current. In electrochemical corrosion, the destruction of metal is associated with the emergence and flow of electric current from one area of the metal to another. When solutions of acids and alkalis act on a metal, the metal gives up its ions to the electrolyte, and itself is gradually destroyed. The electrochemical corrosion process can also occur when two dissimilar metals come into contact. For example, when iron comes into contact with chromium, chromium will be destroyed, and iron with copper will destroy iron.
In some cases, the corrosion process is caused by stray currents spreading in the ground from electrified rails railways and passing through the thickness of the earth, as well as through various metal devices laid in the ground (electrical cables, water pipes). Stray currents reaching metal pipelines and other underground devices located in moist and salty soil create conditions for electrolysis. Ions (electrically charged metal particles) pass into the soil solution (electrolyte); As a result of the loss of elementary metal particles, corrosion pits appear on underground cables, water and sewer pipes.
The corrosion process can be local, when the destruction of the metal occurs in some areas, uniform, when the metal is equally destroyed over the entire surface, and intergranular, when the destruction occurs along the grain boundaries of the metal. A clean, unprotected metal surface is in most cases subject to corrosion processes. various types. The oxide film formed on the surface of some metals can stop the development of the corrosion process. Such protective films appear on the surface of copper, bronze, aluminum. Steel belongs to the metals that poorly resist the corrosion process; destruction of the surface of steel products caused by the corrosion process quickly spreads to the inner layers of the metal,
Losses from corrosion processes cause great material damage to the national economy. This phenomenon can be combated by various means.
Where possible, metals are replaced with other materials that are less susceptible to corrosion. If metal structures cannot be replaced, they are covered with varnishes and enamels. The resulting film protects the metal from the action external environment. To protect against corrosion, metal structures are painted, galvanized, tin-plated, and chrome-plated. In addition, for the manufacture of structures, metals are used that are most resistant to this aggressive environment. For example, low-alloy steels are used in conditions of low humidity and exposure to alkalis, high-alloy steels are used in conditions of high humidity and highly aggressive gases. Alloying with nickel dramatically increases the resistance of steel against atmospheric and underwater corrosion.
Metal building structures are protected from corrosion processes by flame spraying powdered plastic polymers onto their surface, including polyethylene, polypropylene, nylon, as well as special compositions from these materials with or without the addition of powdered fillers and dyes.
The history of mankind goes back more than one thousand years. Throughout the entire period of the existence of our race, there has been stable technological progress, in which man’s ability to handle, create and mine metal played an important role. Therefore, it is quite logical that metallurgy is something without which it is impossible to imagine our life, the normal performance of work duties and much more.
Definition
First of all, it is worth understanding what the modern sphere of production is called scientifically, from a technical point of view.
So, metallurgy is a branch of science and technology that covers the process of obtaining various metals from ore or other materials, as well as all processes related to the transformation of the chemical composition, properties and structure of alloys.
Structure
Today metallurgy is the most powerful branch of industry. In addition, it is a broad concept that includes:
- Direct production of metals.
- Processing metal products both hot and cold.
- Welding.
- Application of various metal coatings.
- Branch of science - materials science. This direction in theoretical study physical and chemical processes focuses on understanding the behavior of metals, alloys and intermetallic compounds.
Varieties
There are two main branches of metallurgy around the world - ferrous and non-ferrous. This gradation has developed historically.
Ferrous metallurgy consists of the processing of iron and all alloys in which it is present. This industry also involves the extraction from the depths of the earth and subsequent beneficiation of ores, steel and iron foundries, rolling of billets, and production of ferroalloys.
Non-ferrous metallurgy includes working with ore of any metal except iron. By the way, they are conditionally divided into two large groups:
Heavy (nickel, tin, lead, copper).
Lightweight (titanium, magnesium, aluminum).
Scientific solutions
There is no doubt that metallurgy is an activity that requires implementation innovative technologies. In this regard, many countries on our planet are actively pursuing research papers, the purpose of which is to study and put into practice a wide variety of microorganisms that would help solve, for example, such a pressing issue as cleaning Wastewater, which are an essential component of metallurgical production. In addition, processes such as biological oxidation, precipitation, sorption and others have already become a reality.
Separation by process
Metallurgy plants can be roughly classified into two main groups:
Pyrometallurgy, where processes take place at very high temperatures (smelting, roasting);
Hydrometallurgy, which consists of extracting metals from ores using water and other aqueous solutions using chemical reagents.
The principle of choosing a site for building a metallurgical plant
In order to understand on the basis of what conclusions a decision is made to build an enterprise in a particular location, it is worth considering the main factors for the location of metallurgy.
In particular, if the question concerns the location of a non-ferrous metallurgy plant, then the following criteria come to the fore:
- Availability of energy resources. Production related to the processing of light non-ferrous metals requires a colossal amount of electrical energy. Therefore, such enterprises are built as close as possible to hydroelectric power plants.
- Required amount of raw materials. Of course, the closer the ore deposits are, the better.
- Environmental factor. Unfortunately, the countries of the post-Soviet space cannot be classified in the category where metallurgical enterprises are environmentally friendly.
Thus, the location of metallurgy is a complex issue, the solution of which should be given the closest attention, taking into account all kinds of requirements and nuances.
To form the most detailed picture in the description of metal processing, it is important to indicate the key areas of this production.
Ferrous metallurgy enterprises include several so-called processing stages. Among them: sinter blast furnace, steelmaking, rolling. Let's look at each of them in more detail.
Blast furnace production
It is at this stage that iron is released directly from the ore. This happens in a blast furnace and at temperatures above 1000 degrees Celsius. This is how iron is smelted. Its properties will directly depend on the course of the smelting process. By regulating the melting of ore, you can ultimately obtain one of the two: processing (used later for steel production) and foundry (iron billets are cast from it).
Steel production
By combining iron with carbon and, if necessary, with various alloying elements, the result is steel. There are a lot of methods for smelting it. We especially note the oxygen-converter and electric melting plants, which are the most modern and highly productive.
Converter melting is characterized by its transience and the resulting steel with the required chemical composition. The basis of the process is the blowing of oxygen through a tuyere, as a result of which the cast iron is oxidized and transformed into steel.
Electric steel-melting method is the most effective. It is thanks to the use of arc furnaces that the highest quality alloy steels can be smelted. In such units, heating of the metal loaded into them occurs very quickly, and it is possible to add the required amount of alloying elements. In addition, the steel obtained by this method has a low content of non-metallic inclusions, sulfur and phosphorus.
Alloying
This process consists of changing the composition of steel by introducing into it calculated concentrations of auxiliary elements to subsequently impart certain properties to it. Among the most commonly used alloying components are: manganese, titanium, cobalt, tungsten, aluminum.
Rental
Many metallurgical plants include a group of rolling shops. They produce both semi-finished and fully finished products. The essence of the process is to pass metal in the gap between the mill rotating in opposite directions. Moreover, the key point is that the distance between the rolls should be less than the thickness of the workpiece being passed. Due to this, the metal is drawn into the lumen, moves and ultimately deforms to the specified parameters.
After each pass, the gap between the rolls is made smaller. Important point- often the metal is not sufficiently ductile when cold. And therefore, for processing, it is preheated to the required temperature.
Consumption of recycled materials
In modern conditions, the market for the consumption of recyclable materials, both ferrous and non-ferrous metals, is steadily developing. This is largely due to the fact that ore resources, unfortunately, are not renewable. Each year of their extraction significantly reduces reserves. Considering the fact that the demand for metal products in mechanical engineering, construction, aircraft manufacturing, shipbuilding and other sectors of the national economy is steadily growing, the decision to develop the processing of parts and products that have already exhausted their service life seems quite reasonable.
It is safe to say that the development of metallurgy is to some extent explained by the positive dynamics of the industry segment - the use of secondary raw materials. At the same time, both large and small companies are engaged in recycling scrap metal.
World trends in the development of metallurgy
In recent years, there has been a clear increase in the output of rolled metal, steel and cast iron. This is largely due to the real expansion of China, which has become one of the leading global players in the metallurgical production market.
At the same time, various metallurgy factors allowed the Celestial Empire to win almost 60% of the entire world market. The rest of the top ten major producers were: Japan (8%), India and the United States of America (6%), Russia and South Korea (5%), Germany (3%), Turkey, Taiwan, Brazil (2%).
If we consider 2015 separately, then there is a downward trend in the activity of metal product manufacturers. Moreover, the largest decline was noted in Ukraine, where a result was recorded that was 29.8% lower than last year.
New technologies in metallurgy
Like any other industry, metallurgy is simply unthinkable without the development and implementation of innovative developments in practice.
Thus, employees of Nizhny Novgorod state university developed and began to put into practice new nanostructured wear-resistant hard alloys, which are based on tungsten carbide. The main direction of application of the innovation is the production of modern metalworking tools.
In addition, in Russia the grate drum with a special ball nozzle was modernized in order to create new technology processing of liquid slag. This event was carried out on the basis of a state order from the Ministry of Education and Science. This step fully justified itself, since its results ultimately exceeded all expectations.
The largest metallurgical enterprises in the world
- ArcelorMittal- a company with its head office in Luxembourg. Its share is 10% of total global steel production. In Russia, the company owns the Berezovskaya, Pervomaiskaya, Anzherskaya mines, as well as the Severstal Group.
- Hebei Iron & Steel- a giant from China. It is completely owned by the state. In addition to production, the company is engaged in the extraction of raw materials, their transportation and research and development. The company's factories use exclusively new developments and the most modern technological lines, which allowed the Chinese to learn how to produce ultra-thin steel plates and ultra-thin cold-rolled sheets.
- Nippon Steel- Representative of Japan. The management of the company, which began operations back in 1957, is seeking to merge with another company called Sumitomo Metal Industries. According to experts, such a merger will allow the Japanese to quickly take first place in the world, ahead of all their competitors.
