Сборник заданий и упражнений по дисциплине «Английский язык» для развития лексических навыков в области профессионально-ориентированного общение по специальности «Металлургия цветных металлов»
учебно-методическое пособие по английскому языку на тему

ГОУ СПО Уральский государственный колледж им. И.И. Ползунова

Сборник текстов и упражнений

по дисциплине «Английский язык»

для развития лексических навыков в области профессионально-ориентированного общение по специальности

«Металлургия цветных металлов»

Екатеринбург, 2009 г.

Автор:  Готочкина Т.В. – преподаватель Уральского государственного колледжа им. И.И.Ползунова

Рецензент:  Малина Л.П. – преподаватель Уральского государственного колледжа им И.И. Ползунова

Пояснительная записка

Данное пособие предназначено для работы со студентами, обучающимися по специальности «Металлургия цветных металлов», и ставит своей целью подготовить их к чтению и переводу соответствующей технической литературы на английском языке, а также сформировать базовые навыки и умения для устного общения на языке по данной специальности.

Пособие содержит адаптированные и оригинальные тексты из иностранных журналов и научно-технической литературы, а также тексты, переведенные с русского на английский язык. Тематика текстов следующая: металлургия, литейное производство, специальные способы литья, виды печей, свойства металлов и сплавов. Содержание текстов соответствует программам специальных дисциплин, и по своей сложности данные тексты предназначены для студентов III курса, имеющих базовые знания по дисциплине «Английский язык».

Тексты снабжены упражнениями, рассчитанными на активизацию лексического и грамматического материала. Выбор упражнений и их последовательность обусловлены характером текстов. К текстам даются пояснения, облегчающие понимание и перевод отдельных мест, представляющих определенную языковую трудность.

Пособие может быть использовано для самостоятельной работы студентов.

Unit 1. METALLURGY

SOME WORDS ABOUT METALLURGY

Metallurgy is one of the oldest of arts but one of the youngest of sciences. Many of our metals were known in ancient times, but it is only within the last century or two that the knowledge of the properties of the metals has made it possible to apply them in any extended way for industrial purposes.

With the development of physics of metals, metallography, theory of heat treatment, and other phases of the science of metals, the field of metallurgy has broadened.

Metallurgy in this broader sense falls into three divisions: chemical or extractive, physical and mechanical. Chemical metallurgy includes the metallurgical processes involving chemical change and the methods of production and refining.

Physical metallurgy deals with the nature, structure, and physical properties of metals and alloys.

Mechanical metallurgy includes the processes of working and shaping metals — processes which do not involve chemical changes.

NOTES AND COMMENTARY

EXERCISES

1. Find in the text the English equivalents of these Russian word combinations.

1. в промышленных целях
2. применять
3. метод производства
4. очищение от примесей, улучшение качества
5. свойства металлов
6. теория термической обработки
7. в широком смысле
8. химическое изменение
9. включать
10. сплавы
11. обработка
12. извлекать

2. Answer the questions.

1. What phases of the science of metals do you know?
2. What does physical metallurgy deal with?
3. What does mechanical metallurgy include?

Unit 2. PHYSICAL PROPERTIES OF METALS AND ALLOYS

The word constitution used with reference to metallic substances does not have the same meaning as composition. Constitution denotes the manner of arrangement of the metal atoms as to geometric form in solid crystals, and the regular or ordered arrangement of different kinds of metal atoms and their relation to each other in such a crystal.

The pattern formed by this orderly arrangement of the atoms is known as the space lattice.

Most metals crystallize with one of the three following lattice structures:

Close-packed cubic: copper, nickel, lead, aluminium, cobalt, silver, gold, platinum.

Body-centred   cubic:   iron,   molybdenum,   tungsten,   chromium.

Hexagonal  close-packed:   zink,  cadmium,  magnesium,  beryllium, titanium.

This union of atoms into a geometric array is the physical difference between liquid and solid metal.        

The formation of metal crystals within  a melt begins at each cooling surface of the liquid mass and extends from the exterior to the interior as heat is lost from the mass. Every change in the conditions of cooling, such as increasing or decreasing the rate at which heat is conducted away from the freezing mass, will have an influence on the size and shape of the crystals and, therefore, on the constitution and properties of the solidified mass.

Melting and Boiling Points. - The temperature at which a metal melts, is called the melting point, the metals of lower melting points are generally the soft metals and those of high melting the hard metals.

The boiling point of a substance depends on the surrounding-pressure. The term "boiling point" refers to the temperature at which the metal boils under normal atmospheric pressure.

 Electrical   Conductivity. - The  electrical   conductivity of  a substance is the electrical conducting power of a unit length per  unit of cross-sectional  area.  The electrical  resistance  of metals or alloys is increased by decreasing the size of the crystals and, therefore, increasing the number of crystal boundaries. In general, all metals increase in resistivity with increase in  impurities.  The resistivity of metals  is  also  increased  in most cases by an increase in temperature.

Heat Conductivity. - Heat conductivity is measured as the heatconducting ability of a unit length or thickness of a substance per unit of cross-sectional area.

Magnetism. - Magnetism is measured as the magnetic force exerted by a unit volume of a substance under standard magnetizing force.  Iron, cobalt and  nickel  are the only metals possessing considerable magnetism at room temperature, and they become non-magnetic when heated to a certain temperature.  Strong permanent magnets have been  made chiefly of one of several  compositions of steel,  but in  recent years  a number of magnet alloys of much greater magnetism, able to exert   forces  many times  their  own  weights,   have  been   developed.

Density and Porosity. - Porosity, the quality of containing pores is lack of denseness. Density, on the other hand, denotes weight per unit of volume. The distinction will be manifest from the fact that some heavy metals, like grey cast ironware porous enough to leak under heavy hydraulic pressures, whereas some lightweight metals, like aluminium, are dense and compact.

Most metals expand on heating and contract on cooling.

Colour. - Most of the metals are silvery white or grey in colour. Copper is the only red metal, and gold the only yellow one, although a number of copper-base alloys are also yellow. All solid metals have metallic lustre, although the true colour and lustre of many metals are often obscured by a coating of oxide — which may be white, grey, red, brown, bluish, or black.

NOTES AND  COMMENTARY

EXERCISES

1. Answer the questions.

1. Name the main physical properties of metals and alloys.
2. What does the boiling point of a substance depend on?
3. When do most metals extend?
4. What is the difference between liquid and solid metal?
5. What metals possess considerable magnetism at room temperature?

2. Match the term with its definition.

3. Find in the text sentences containing the following words and translate them into Russian.

1. solid crystals
2. composition
3. surface
4. cooling
5. electrical resistance
6. lightweight metals
7. to leak
8. resistivity
9. the solidified mass
10. denseness

4. Find 13 words on the topic in the crossword-puzzle and give their Russian equivalents.

Unit 3. MECHANICAL PROPERTIES OF METALS AND ALLOYS

Strength. - The strength of a material is the property of resistance to external loads or stresses without incurring structural damage.

The strength of metals and alloys depends upon two factors, namely, the strength of the crystals of which the metals are constructed and the tenacity of adherence between these crystals.

Stress and Strain. - A stress is the force within a body which resists deformation due to an externally applied load. If this load acts upon a surface of unit area, it is called a unit force and the stress resisting it a unit stress.

When an external force acts upon an elastic material, the material is deformed and the deformation is in proportion to the load. This distortion or deformation is strain.

Elasticity. - Any material subjected to an external load is distorted or strained. Elastically stressed materials return to their original dimensions when the load is released if the load is not too great. The property of regaining the original dimensions upon removal of the external load is known as elasticity.

The Nature of Elasticity. - The elasticity of a metallic substance is a resistance of its atoms to separation or compression or rotation about one another, and thus is a fundamental property of the material. So elasticity is demonstrated as a function of atomic forces.

Yield Point. - This is a point on the stress - strain curve at which the stress levels off or actually decreases while strain continues. The term is strictly applicable only to mild steels.

Ultimate Strength. - The greatest load that the specimen has supported divided by the original cross-sectional area is called the ultimate tensile strength or the ultimate strength of the piece.

      Ductility. - Ductility is the capacity of a metal to be permanently deformed in tension without breaking.

      Toughness. - Toughness has been defined as the property of absorbing considerable energy before fracture. The toughness of a metal is indicated by the amount of slip which may occur within the crystals without resulting in rupture of the metal.

Malleability. - Malleability is the property of a metal which permits permanent deformation by compression without rupture.

Brittleness. - Brittleness implies sudden failure. It is the property of breaking without warning, i.e., without visible permanent deformation.

Failure of metals and alloys under repeated or alternating stresses, too small to produce even a permanent deformation when applied statically, is called fatigue failure.

Corrosion Fatigue. - Failure by corrosion fatigue is a fatigue failure in which corrosion has lowered the endurance limit by the formation of pits that act as centers for the development of fatigue cracks.

Hardness. - The quality of hardness is a combination of a number of physical and mechanical properties.

NOTES AND COMMENTARY

EXERCISES

1. Make words out of these letters and translate them into Russian.

1. tacesinser
2. ibsivel
3. ranetexl
4. canytiet
5. thgenrst
6. rooornisc
7. recendanu
8. larufei
9. guhsensot
10. lilelbaityma

2. Name the property according to its definition.

1. - the property of regaining the original dimensions upon removal of the external load.
2. - the property of breaking without warning.
3. - a combination of a number of physical and mechanical properties.
4. - a point on the stress - strain curve at which the stress levels off or actually decreases while strain continues.
5. - the capacity of a metal to be permanently deformed in tension without breaking.
6. - the property of resistance to external loads or stresses without incurring structural damage.
7. - the property of a metal which permits permanent deformation by compression without rupture.

3. Make up definitions out of these words and name the property.

1. separation, another, atoms, a resistance, or, or, of, to, rotation, one, about compression.
2. which, permanent, a metal, the property, of, deformation, without, by, compression, rupture, permits.
3. mechanical, a number, a combination, properties, of, of, and, physical.
4. before, absorbing, the property, fracture, considerable, of, energy.
5. due to, within, load, deformation, a body, which, an, applied, the force, externally, resists.

4. Finish the sentences according to the text.

1. Ductility is the capacity of a metal to be permanently deformed …
2. Elasticity is demonstrated as …
3. When an external force acts upon an elastic material …
4. Elastically stressed materials return to their original dimensions when …
5. The strength of metals and alloys depends upon two factors: …

Unit 4. Foundry equipment.

FOUNDARY

METAL CASTING

One of the basic processes of the metal-working industry is the production of metal castings. Numerous methods have been developed through the ages for producing metal castings, but the oldest method is that of making sand castings in the foundry. Primarily, work consists of melting metal in a furnace and pouring it into suitable sand molds, where it solidifies and assumes the shape of the mold. However, the operation of making sand castings is not as simple as it seems

Metal-castings methods may be classified into three groups depending upon the type of mold used and the manner in which the molten metal is introduced into the mold.

The mold may be made from heat-resisting material, such as sand, some suitable ceramic material, or plaster. The kind of material chosen to make the mold is, of course, determined primarily by the melting temperature of the cast metal. Molten metals may be poured into the mold by gravity or, on the other hand, pressure may be applied to force the liquid metal into the mold. The latter method is known as die casting. Die-casting pressure may be furnished by air, hydraulic means, mechanical means, or centrifugally.

Among the mold materials, sand is used more than all others, since it can be packed to any required shape with small effort.

This method of production is relatively simple, inexpensive, and is not limited to any particular type of metal or to certain sizes and shapes of castings. Of course, sand molds are used only once, and each casting requires a new mold.

Wider use of the permanent type of mold made from steel, iron or any other suitable metal, depending upon the melting temperature of the cast metal, is therefore greatly desired.

Bronze molds are employed at times for casting metals and alloys of very low melting temperature such as zinc-base and lead-base alloys.

Modern casting techniques also permit that steel molds, coated inside with refractory material, also be successfully used for production of iron and steel castings.

The metal molds are usually made in two parts which are either clamped together or closed by a screw or other suitable device. The molten metal may be introduced into the mold either by gravity or pressure.

The inner surfaces of the metal mold are in most cases finished smooth. They can be re-used. These qualities make them superior to sand castings.

NOTES AND COMMENTARY

EXERCISES

1. Learn the words and special terms on foundary.
2. Answer the questions.

1. What is the oldest method of casting?
2. How may metal-casting methods be classified?
3. Put the steps in the right order according to the technology:

• pouring the metal into suitable sand molds
• solidifying
• making sand molds
• melting metal in a furnace

4. Why is sand used as mold material?
5. What other mold materials do you know?
6. What methods of pouring molten metals into a mold do you know?
7. What does the melting temperature of the cast metal determine?

3. Write the English equivalents of these Russian words and make up sentences of your own with them.

1. литье
2. печь
3. форма
4. жидкий металл
5. использовать вторично
6. выливать
7. производство
8. в зависимости от
9. требуемая форма
10. подходящий

Unit 5. SAND  MOLDING   EQUIPMENT AND  MATERIALS

There are three principal methods of making sand molds. Green-sand or damp-sand molds are formed by mixing silica, 8 per cent or 15 per cent clay, and a small amount of water. Green-sand molds are recommended for cast iron.

Dry-sand molds are formed by mixing sand of somewhat coarse grain with a clay-bonding material and water, and then baking the mixture dry. These molds are used where heavy work is to be cast. Dry-sand molds are usually made up one day, baked overnight, and assembled and cast the next day. Dry-sand molds are recommended for steel castings.

A modified sand mold (also called a skin-dried mold) has been found suitable for certain types of sand castings. Silica sand (silicon dioxide) is mixed with a dry-sand bond. The mixture is packed around the pattern to a thickness of 1/2 inch thus forming a partial mold, which is permitted to dry out. When the partial mold is dry the remaining portion of the mold is completed with green sand.

There are three classes of materials for molding that are kept in stock in the foundry. Molding sands   (light, medium and heavy), facings (graphite for blacking or finely ground soft coal) and miscellaneous (fire clay, core binders and parting compounds).

Light sand is used for the castings such as stove plate. The sand should be very fine to bring out this detail; it must be strong; i.e., high in clay content, so that the mold will retain every detail as the metal rushes in. Fine sand can be used for such casting because the work will cool so quickly that after the initial escape of the air and steam there will be very little gas to come off through the sand.

Medium sand is used in bench work and light floor work-such as making machinery castings having from 1/1 to 2 sections. These castings are less fine than those molded in light sand. Therefore, the molding sand for this type of casting is coarser than in the case previously described.

Heavy sand is used for very large iron and steel castings. This sand is high in silica, low in lime, and its grain is coarse in order to resist the heat of the molten metal and enable the formed gases to pass through the molding sand for a long time after the molten metal is poured. This type of molding sand must be held firmly together by a large proportion of clay which makes a strong bond.

Foundry Facing Materials are either applied or mixed with the molding sand that comes in contact with the melted metal. The object is to give a smooth surface to the casting.

Different forms of carbon are used for facing purposes-because carbon will glow and give off gases, but it will not melt. The principal carbon facing is graphite.

NOTES AND COMMENTARY

EXERCISES

1. Read the sentences and say whether they are true or false.

1. There are four classes of materials for molding that are kept in stock in the foundry.
2. Medium sand is used for the castings such as stove plate.
3. Heavy sand is used for very large iron and steel castings.
4. Dry-sand molds are usually made up two days.
5. Dry-sand molds are recommended for aluminium castings.

2. Make up sentences out of these words.

1. carbon, facing, forms, are, different, purposes, used, of, for.
2. Sand, three, method, molds, making, are, principal, there, of.
3. With, portion, completed, green, when, the mold, mold, the, sand, the, partial, of, is, dry, remaining, is.
4. Are, overnight, molds, dry-sand, usually, baked.

Stove, for, light, such, sand, the, plate, castings, used, is, as.

3. What is the Russian for these words and word combinations?

1. facing materials
2. clay-bonding material
3. silicon dioxide
4. to resist the heat
5. graphite for blacking
6. to give a smooth surface
7. the remaining portion
8. mixed with dry-sand bond
9. glow and give off gases
10. small amount of water

Unit 6. TYPES OF MOLDING MACHINES

Modern molding machines successfully perform a considerable amount of work that was done by hand.

Those molding machines that are used primarily for packing sand in flasks can be classified as squeezer machines, jar (or jolt) machines, jolt squeezers, and sand slingers. Other types of machines employed in molding are pattern-draw machines (stripping-plate machines and stripper machines) rollover machines, combination machines, vibrators, and others.

The squeezer machine rams sand into the flask, which is placed between the machine table and an overhead plate, thus obtaining uniform density of the sand contained in the flask.

The jar or jolt machine consists of a rugged base cylinder and piston which is attached to the machine table. The table is lifted by air pressure directed against the piston from below, and is then permitted to drop. This action produces a jar which rams the molding sand evenly in the flask. The operation is very rapid, and some of the jolt machines used for small flasks give more than a hundred blows per minute.

The jar-squeezer machine, also called the jolt-squeezer machine, combines the operating principles of the jolt machine and the squeezer machine. A complete mold, drag and cope, is produced by means of this machine.

Machines called sand slingers are sand-filling and ramming devices used in the rapid molding of large castings. These machines can be used in combination with other molding devices such as the roll-over machine and the pattern-draw machine.

Machines of various kinds have been developed for the purpose of drawing pattern out of the mold. There are two types of pattern-drawing machines: the stripping-plate machine and the stripper.

In the stripping-plate machine, the pattern is fitted through a plate that fits accurately around the pattern. The patterns are drawn through the plate, either by moving the pattern supports down with a lever or by raising the plate and the mold half up, free from the pattern. The stripping-plate machine is best adapted to that class of work which offers difficulties in drawing the pattern from the sand.

A stripper is a machine that either lifts the mold away from the pattern or lifts the pattern away from the mold.

NOTES AND COMMENTARY

EXERCISES

1. Say what type of machine does this or that operation.

• rams sand into the flask
• molds rapidly large castings
• draws patterns out of the mold
• lifts the mold away from the pattern

2. Describe the work done by every machine.

Unit 7. CASTING METALS

Cast Iron.— The term cast iron is applied to ferrous alloys. Among the ferrous metals, cast iron occupies first place and is recognized as one of the cheapest materials used in the manufacture of everyday life products. Cast iron is not considered a very strong or tough structural material, but it is the most economical. Its low melting point, low shrinkage, good fluidity, and machinability are properties that recommend its use.

Pig Iron.— The chief raw material for cast iron is pig iron, which is produced in a blast furnace by smelting iron ore with coke and a flux (substances promoting fusion) such as limestone. The final analysis of the pig iron is substantially determined by the kind of iron ore used in the smelting process.

Pig iron got its name from the shape of the molds in which metal from the blast furnace was cast. Originally, the pigs were cast in sand molds.

Modern large-volume production of pig iron is carried out by casting blast-furnace metal by means of a large machine, which is in principle an endless conveyer chain of pig molds.

Some pig irons are used in gray-iron foundries, and are called foundary pig irons. Pig iron used for making steel by the acid Bessemer process or the acid open-hearth process is known as Bessemer pig iron. Basic pig iron is used for the basic open-hearth process.

Non-Ferrous Metals. — The non-ferrous metals used in the foundary are usually alloys of two or more metals. Non-ferrous castings include those composed of copper-base alloys (brass and bronze), aluminium-base alloys, zinc-base alloys, tin-base alloys, lead-base alloys, bearing metals, and some special alloys composed of magnesium or nickel and other metals.

NOTES AND  COMMENTARY

EXERCISES

1. Answer the questions.

1. What metal occupies the first place among the ferrous metals?
2. Where did pig iron get its name from?
3. What is pig iron used for?
4. What is the final analysis of iron determined by?
5. How is pig iron produced?

2. Find the sentences with these words in the text and translate them into Russian.

1. open-hearth
2. blast furnace
3. smelting
4. shrinkage
5. bearing metals

Unit 8. Types of furnaces.

Task:

     -    read the texts describing different types of furnaces

• make a plan to each text
• make up 5 questions to each of the texts
• retell any text you like

THE  CUPOLA  FURNACE

The cupola is the oldest type of furnace and the most economical. It may be obtained in different sizes and can be operated for as long a time as may be required to produce a given amount of melted metal. It is difficult to produce metal of precisely uniform quality in the cupola as compared to furnaces in which uniformity of the molten material can be controlled by frequent and periodic tests and adjustment. Cupola capacities vary from 1 to 15 tons of metal per heat (the amount of metal melted at one time).

The cupola is a cylindrical shell constructed from boiler plate and lined  with firebrick. The main furnace structure is usually supported on cast-iron legs, and the opening at the bottom of the furnace may be closed by cast-iron doors, which swing up into position and are held closed by an iron upright at the   center. Refractory sand protects these doors during the melting of the   charge, which is placed over the layer of sand. At the end of the   melting   operation,   the doors swing out of the way and materials remaining from the  charge drop down through the opening.

On one side of the cupola, level with the bottom, is the breast opening for lighting the fire. This opening is also used as the tap hole. Opposite the tap hole, and somewhat higher, is the slag hole. The charging door is located approximately halfway up the vertical shell. The top of the cupola is open except for a metal shield.

A single row of openings or tuyeres is arranged around the circumference of the shell's interior at its base as a means of introducing air to the coke bed. A wind box, externally circling the cupola at the level of the tuyeres, supplies the air.

Cupola Zones. — A foundry cupola is generally divided into a number of zones: the crucible zone, tuyere zone, combustion zone, melting zone, preheating zone, and the stack zone.

The crucible zone is located at the bottom of the cupola; it is situated in the space between the sand bottom of the furnace and the bottom of the tuyere openings. Molten iron and slag accumulate in this space between the burning pieces of coke.

The tuyere openings are above the cruicible and take up a space from 3 to 6 inches in depth depending upon the size of furnace.

The combustion zone is that section of the cupola which extends from the bottom of the tuyeres to the top of the coke bed.

The melting and preheating zones extend from the top of the combustion zone to the charging door. The location of the charging door depends upon the size of the cupola. High charging doors, however, are recommended for large cupolas which are run all day, since greater fuel efficiency can be gained from the use of such charging doors.

The purpose of the stack, which is another zone of the cupola, is to carry off the waste gases. It is located above the charging door. A roof hood is usually fastened to the stack to prevent leaks around the cupola.

Diagram of a Foundary Cupola for Melting Cast Iron

NOTES AND COMMENTARY

THE   BLAST   FURNACE

The modern blast furnace is a tall circular structure about 100 ft. high built of firebrick and reinforced by a steel shell on the outside. The interior form is circular. A heavy concrete and brick foundation is built either on bedrock or upon heavy pilings driven deep into the earth if bedrock is too far below the surface.

Iron is reduced from the ore in the furnace by means of coke charged with ore, and the impurities are fluxed or slagged by means of limestone also charged with the ore. The air blown through the furnace is heated by means of stoves that constitute an important part of the apparatus of the blast furnace. These stoves heat the brickwork in them to about 1150°C and the air pumped through the stoves is thus heated to about 900°C before it is blown into the furnace.

The ore, coke, and limestone are conveyed from the ground to the top of the furnace by means of two cars running on an inclined hoist. The cars dump the charge into a hopper from which it is then dropped into the furnace by lowering first the upper bell, then lowering the lower bell. The use of these two bells prevents gases and flame from being blown into the air from the top of the furnace every time it is charged. Hot air is blown into the furnace through the tuyeres in the hearth of the furnace.

As the iron and slag are formed, they drop to the hearth at the bottom of the furnace. Since the iron is heavier than the slag, it settles to the bottom while the slag floats on the top of the molten iron. There are two holes in the hearth of the blast furnace. The iron is tapped from the lower hole; the slag is tapped from the upper hole. Many of the impurities in the ore are collected and removed with the limestone in the form of molten slag.

The iron runs from the furnace into troughs which convey it to a ladle. The iron in the ladle is then cast into pigs or else taken while molten to the steel making furnaces.

NOTES AND  COMMENTARY

THE BESSEMER CONVERTER

In the Bessemer process of making steel air is blown through the molten pig iron, and the oxygen of the air combines with the carbon, manganese, and silicon of the pig iron. This action generates heat and frees the iron from the major part of its impurities thus converting the iron into steel.

The Bessemer converter, in which the process takes place, is a pear-shaped tilting vessel made of steel plates and lined with heat-resisting bricks and clay. The top of the converter is cut off to form a mouth through which molten metal is charged and discharged. In the bottom of the vessel are a number of holes through which air is blown.

When the air blast is turned on, a shower of sparks bursts from the mouth of the converter. Immediately thereafter appear short ruddy flames and a dense cloud of reddish-brown fumes caused by the burning of the silicon and manganese in the iron. In about five minutes this part of the refining action is accomplished, and the next stage, the removal of carbon, begins.

The ruddy flames become more luminous, changing to a

yellowish white.

For about ten minutes the glare continues, and during that time the converter emits a deep roar caused by the violent generation of gas within it.

Suddenly the flame drops, and the operator must diminish the blast of air and remove the metal from the converter.

Bessemer steel is used because of the low cost of the process.

Today we have a new, more perfect technology of converting pig iron into steel in which the blast of air is replaced by a jet of nearly pure oxygen.

NOTES AND  COMMENTARY

THE  OPEN   HEARTH   FURNACE

The name open hearth is given to it because the hearth of the furnace is exposed to the sweep of the flames which melt the steel.

The open-hearth process is one of the most important methods of making steel. It is much slower than the Bessemer but it is easier to control, and for that reason it is more frequently used.

The furnace is lined with firebrick to withstand the very high temperatures used. The charge consists of molten pig iron, scrap iron and steel and some hematite. Lime is added to the charge to take out the phosphorus and sulphur as slag. Manganese, carbon, nickel, vanadium, or other materials are added to make the kind of steel desired.

The fuel is blown into furnace through one of the two large openings, or ports, located on each end of the furnace. To facilitate combustion, previously heated air is blown through the port along with the fuel. Combustion occurs above the hearth, and the smoke and other products of combustion escape through the ports at the other end of the furnace.

Beneath the furnace are two large chambers through which air or gas flows freely.

There are three stages in the operation of this furnace. The first is known as the process of charging; the second — as the melting down process; the third — the period of refining. The period of refining is especially important and requires the constant supervision of the operator. The refining consists first in removing objectionable impurities and then controlling the elements other than iron which the final product must contain. Alloying elements are added to the steel before it is tapped or when it is in the ladle.

NOTES AND COMMENTARY

THE ELECTRIC FURNACE

The finest grades of steel are produced by the electric furnace method. Stainless and heat resistant steels are made almost exclusively by that process.

Electricity is used only for the production of heat and does not of itself impart any superior quality of steel. Nevertheless, the electric furnace method gives certain advantages impossible in other steel melting processes. The electric furnace generates extremely high temperatures. The temperature is at all times under precise control and is easily regulated.

The production of heat by electricity is unique, oxygen is not necessary to support combustion and the atmosphere within an electric furnace may be regulated at will.

The electric furnace is a circular steel shell resembling a huge tea-kettle in general appearance. It is mounted on rockers so that the furnace can be tilted to pour off molten metal and slag. The bottom of the furnace consists of a layer of heat resistant materials below which it is lined with refractory bricks. The side walls which are also lined with refractory bricks contain three or more openings.

The roof of the furnace is lined with 250 mm or more of refractory bricks and is shaped like a flat dome. Through this dome great columns of carbon reach into the furnace. These are the electrodes which carry the current to the steel charge.

NOTES AND COMMENTARY

Unit 9. Metals and their alloys.

Task for selfstudy:

• read the texts
• write down all special terms to each of the texts
• answer the questions
• make a report on any metal you like

ALLOYS

Pure metals are comparatively seldom used; in engineering, application is made chiefly of alloys which consist of two or more metals, or of metals and metalloids.

Alloys are metallic solids, complex in composition,
formed as a result of the freezing of the melt — the liquid
solution of two or more metals, or metals and metalloids.

Each constituent of an alloy is called a component. Alloys may be binary (two-component), ternary (three-component), etc.

The ability of various metals to form alloys differs greatly and, therefore, the structure of various alloys after solidification may also be very diverse.

In the liquid state, alloys are entirely homogeneous and from the physical point of view constitute a single phase. Nonhomogeneity may appear when an alloy is transformed from the liquid to the solid state, i.e. several solid phases are formed. After solidification, alloys may consist of one, two or more phases depending upon the nature of their components. Certain metals are not mutually soluble in the liquid stale; they form two layers with different specific weights (e.g., lead and iron, lead and zinc, etc.). It is difficult to form an alloy in such cases since it is necessary to mix the metals into each other.

            ALUMINIUM AND ITS ALLOYS

Next to oxygen, aluminium is the most abundant element in nature: about 7.45 per cent of the earth's crust consists of aluminium.

Aluminium is extracted from rock with a high alumina content. The most important sources are bauxite, kaolin, nepheline and alunile.

Bauxite is the principal source of aluminium. The less silica in a bauxite the higher its quality as an aluminium ore. Kaolin clays are very abundant in nature but the extraction of aluminium from these ores presents difficulties due to the considerable amount of silica present.

The most important properties of aluminium are its low specific gravity (2.7), high electrical and thermal conductivities, high ductility, and corrosion resistance in various media.

Pure aluminium has only few applications; it is used for the manufacture of electrical wire, chemical apparatus, household utensils and for coating other metals.

Aluminium alloys are more widely used in industry. Wrought aluminium alloys have a high mechanical strength which in some cases approaches the strength of steel. Wrought aluminium alloys are further classified as non-heat-treatable and heat-treatable alloys. .Wrought aluminium alloys also include complex alloys of aluminium with copper, nickel, iron, silicon and other alloying elements. Complex wrought aluminium alloys of the duralumin (dural) type and certain others have found most extensive application in many industries.

Several grades of duralumin are available in the Russia. They are identified by the Russian letter Д followed by a figure indicating the number of the alloy in the series. Duralumin, grade Д-1 can be obtained in the form of sheets, bar stock and tubing; grades Д-6 and Д-16 аre usually produced in the form of bars, and grade Д-ЗП is made as wire for rivets.

Answer the following questions:

1. What elements are the most abundant in nature?
2. What   are   the   most   important   sources   of   aluminium?
3. What are the most important  properties  of aluminium?
4. Is pure aluminium widely used?
5. Do  wrought aluminium  alloys  have a high  mechanical strength?
6. How are wrought aluminium  alloys  further classified?
7. What complex alloys do wrought aluminium alloys also include?
8. What aluminium alloys have found most extensiveapplication in many industries?
9. How are various grades of duralumin identified?

MAGNESIUM AND ITS ALLOYS

Magnesium has a specific gravity of approximately 1.7; its alloys are the lightest of all engineering metals employed.

The melting point of magnesium is 650° C; its boiling point is 1007° C. Magnesium is very inflammable and burns with a dazzling flame, developing a great deal of heat.

The mechanical properties of magnesium, especially the tensile strength, are very low and therefore pure magnesium is not employed in engineering.

The alloys of magnesium possess much better mechanical properties which ensure their wide application.

The principal alloying elements in magnesium alloys are aluminium, zinc and manganese. Aluminium, added in amounts up to 11 per cent, increases the hardness, tensile strength and fluidity of the alloy. Up to 2 per cent zinc is added to improve the ductility (relative elongation) and castability. The addition of 0.1-0.5 per cent manganese raises the corrosion resistance of magnesium alloys.

Small additions of cerium, zirconium and beryllium enable a fine-grained structure to be obtained, they also increase the ductility and oxidation resistance of the alloys at elevated temperatures.

Magnesium alloys are classified into two groups: wrought alloys, grades MA1, MA2, casting alloys, grades MЛ4, MЛ5.

Wrought magnesium alloys MA1 and MA2 are chiefly used for hot smith and closed-die forged machine pants. They are less frequently used as  sheets,  tubing or bar stock.

Magnesium casting alloys MЛ4 and MЛ5 are widely used as foundry material though their castability is inferior to that of aluminium-base alloys.

Answer the following questions:

1. What specific gravity has magnesium?
2. What is the melting point of magnesium?
3. Why is  pure  magnesium  not  employed  in  engineering?
4. What are the principal alloying elements in magnesium alloys?
5. How much aluminium is added to magnesium?
6. How much zinc is added to magnesium?
7. How much manganese is added to magnesium?                                          8. For what purpose are small  additions  of  cerium, zirconium and beryllium added to magnesium?

COPPER AND ITS ALLOYS

Copper is a valuable metal. Its wide application in many fields of engineering is due to its exceptionally high electrical and thermal conductivity, low oxidisability, good ductility and to the fact that it is the basis of the important industrial alloys, brass and bronze.

The raw materials for the production of copper are sulphide or oxide copper ores. Most of the copper is smelted from sulphide ores (about 80 per cent) while oxide ores account for only 15 to 20 per cent. Sulphide ores are more wide-spread in nature due to the higher affinity of copper for sulphur than for oxygen.

  The most abundant copper sulphide ore is copper pyrite containing the mineral chalcopyrite (Cu2Fe2S4). In some cases, the so-called copper glance is used; it contains the mineral chalcocite (Cu2S). All copper ores are very lean as they contain only from 1 to 5% Cu. Therefore, before smelting they must be concentrated by flotation. Flotation converts lean copper sulphide ores into a concentrate containing from 15 to 20% Cu.

Before smelting, the copper concentrate and rich copper sulphide ores are subjected to an oxidising roasting process at 600—900° C thereby part of the sulphur is removed in the form of a gas. This gas is trapped and utilised in the production of sulphuric acid.

Various grades of copper are used for engineering purposes. It must be noted that even a minute amount of impurities sharply alters the properties of pure copper.

The mechanical strength of pure copper is not high and depends upon the degree of deformation (reduction in working). Pure copper is used chiefly for electrical engineering products such as cables, busbars and wire.

The copper alloys are more widely employed. The alloying of copper with other elements increases the strength of the metal in some cases and improves the anticorrosive and antifriction properties in others. Copper alloys comprise two main groups — brasses and bronzes. Alloys of copper and zinc are called brasses. The addition of appreciable amount of tin, nickel, manganese, aluminium and other elements to copper-zinc alloys imparts higher hardness, strength and other desirable qualities. Complex copper-zinc alloys comprising three, four or more components are special brasses.

In Russia brasses are identified by means of the Russian letter Л (the first of the Russian word for brass) followed by letters designating the chief elements and numbers which indicate percentage content of these elements. Thus, grade ЛT 96 is the brass tombac (T) containing 96% Cu and Zn. The designation of gradе ЛЖМЦ-59-l-l indicates that the brass contains 59% Cu, 1 % Fe, 1 % Mn, the remainder is Zn.

Alloys of copper with a number of elements including tin, aluminium, silicon, manganese, iron and beryllium are called bronzes. Tin bronzes are divided into two groups: wrought bronzes, containing up to 6% Sn, and casting bronzes, containing over 6% Sn. Special bronzd are copper-base alloys in which the principal admixtures are Al, Ni, Mn, Si, Fe, Be and others. Special bronzes are fully equivalent substitutes for the more expensive tin bronzes and, therefore, have great economical value. These bronzes are designated on the same principle as brasses. The designation begins with the Russian letters Бp (the first two letters of the Russian for bronze) which are followed by letters indicating the main elements and numbers showing the average percentage of these elements.

Certain   grades   of   special   bronzes    deserve   more detailed consideration. Aluminium bronzes contain from 4 to 11% Al; their high mechanical  properties  and corrosion   resistance   considerably   surpass   those   of   tin bronzes    and   brasses.    The   castability    of   aluminium bronzes is good and the are frequently used in foundry practice. Sheets, strips, bars and wire are made of grades БpA5  and   БpA4  by  the   rolling   process.   Aluminiur bronzes with admixtures of iron and manganese, grades БpAЖ9-4,     БpAЖMЦ10-3-1.5 and БpAMЦ9-2, are suitable for castings and for working, especially for smith and closed-die forging.

Answer the following questions:

1. What are the raw materials for the  production   of copper?
2. Why must all copper ores be concentrated by flotation?

3. Whаt purpose is pure copper chiefly used for?
4. What properties does the alloying of copper with other elements increase?
5. What main groups do copper alloys comprise?
6. What alloys of copper are called bronzes?

7. Into what groups are bronzes divided?
8. Why are aluminium bronzes frequently used  in foundry practice?

TITANIUM AND ITS ALLOYS

As an engineering material titanium has been widely applied only in the last years.

Titanium is a silvery-white metal which melts at approximately 1668°C and has a specific gravity of 4.505. Commercially pure titanium possesses high strength properties. The tensile strength of most titanium alloys ranges from 100 to 140 kg/mm2, in conjunction with high elongation.

The hardness, tensile strength and yield point of titanium are increased with the degree of cold deformation. The elongation value drops rapidly when the degree of cold deformation (reduction) exceeds 50 per cent and becomes equal to 10 per cent. Impurities found in commercial titanium can be divided into two groups: elements which form interstitial solid solutions with titanium (O2, N, C and H2) and elements which form substitution solid solutions (Fe and other metallic elements). The first have a much greater effect on the mechanical properties than those in the second group.

Even very small amounts of oxygen and nitrogen in titanium alloys sharply reduce the ductility. A carbon content of more than 0.2 per cent reduces both the ductility and impact strength of a titanium alloy. It is supposed that the brittleness of titanium is a result of strain ageing and is connected with the presence of dissolved hydrogen in the beta-phase.

Titanium and its alloys are hardened either by a surface heat treatment followed by ageing at 400°—500° C or by producing a case which contains nitrogen, carbon and boron Industrial titanium alloys contain vanadium, molybdenum, chromium, manganese, aluminium, tin, iron or other elements, singly or in various combinations.

A combination of high mechanical properties with low   specific  weight   and  excellent  corrosion  resistance enables titanium to be used in building supersonic air craft.

Answer the following questions:

1. What is titanium?
2. What does the hardness, tensile strength and yield point of titanium depend upon?
3. Do very small amounts of oxygen and nitrogen in titanium alloys reduce the ductility?
4. How are titanium and its alloys hardened?
5. What constituents  do   industrial  titanium   alloys contain?

Литература

1. Алехина М.С. Английский для металлургов. М.: Русский язык, 2005.
2. Андреев Г.Я., Гураль Л.Л., Лев А.Л. Сборник технических текстов на английском языке. М.: Издательство «Высшая школа», 1972.
3. Иллюстрированный словарь английского и русского языка с указателями. М.: Живой язык, 2003.
4. Парахина А.В. Пособие по переводу технических текстов с английского языка на русский. М.: Издательство «Высшая школа», 1972.

Contents (Содержание)

Пояснительная записка…………………………………………………………...3

Unit 1. Metallurgy

(Глава 1. Металлургия)…………………………………………………………….4 Unit 2. Physical properties of metals and alloys

(Глава 2. Физические свойства металлов и сплавов)…………………………5

Unit 3. Mechanical properties of metals and alloys

(Глава 3. Механические свойства металлов и сплавов)……………………...8

Unit 4. Foundry equipment.

(Глава 4. Оборудование литейного завода)……………………………………10 Unit 5. Sand  molding equipment and materials

(Глава 5. оборудование и материалы для литейных форм из песка)……….13

Unit 6. Types of molding machines

(Глава 6. Типы машин для создания литейных форм)………………………15

Unit 7. Casting metals

(Глава 7. Литье металлов)……………………………………………………….17

Unit 8. Types of furnaces.

(Глава 8. Типы печей)…………………………………………………………...18

Unit 9. Metals and their alloys.

(Глава 9. Металлы и их сплавы)………………………………………………...24

Литература……………………………………………………………………….29