density, hardness, heat conductivity, electrical conductivity, weight.

softness, narrowly, passive, unknown, the lightest, heavy, more, temporary, above, least, the best.

1. Lithium is (light) metal and has the density of 0.534.

2. Osmium is (heavy) than platinum.

3. Copper is (good) conductor.

4. Chromium is (hard) metal, it can even cut glass.

5. Because of its physical properties cast iron is (important) for engineers than aluminium.

6. Knowledge of physical properties of metals is one of (important) skills of (good) engineer.

1. What are the uses of metals based upon?

2. What do the metals vary in?

3. Do metals vary in degree of chemical activity? How do they vary?

4. What light metals and heavy metals do you know?

5. Is osmium the lightest or the heaviest metal?

6. What is the most important mechanical property of metals?

7. Are all metals the conductors of electricity?

8. What is the resistance determined by?

Words and word combinations to be memorized:

доменна піч, металургійний завод, чавун у чушках, сировина, руда, тиск, опір, фурма, шихта, матеріали, що подаються, шахта (печі), вогнетривка цегла, тигель, зона плавлення, шлак, виливки, сірий чавун, вагранка, стальна оболонка, завантажувальний люк, подова плита, отвори, плавильна одиниця, холоста колоша (завалка), прошарок коксу, кільцева труба, необроблений матеріал, флюс, підтримувати процес згорання, залізні виливки, розплавлені продукти, хімічні реакції, споживати, продувати.

The modern blast-furnace constitutes the largest and most complicated type of metallurgical plant. Such a plant is capable of producing more than one thousand tons of pig iron a day. It consumes large quantities of raw materials. The material entering the blast furnace consists of the iron ore, the flux (limestone), and a fuel.

The blast-furnace derived its name from the fact that the air to support combustion must be forced into it under pressure, because of the resistance offered by the column of material within the shaft to passage of the combustion gases. The air is usually blown in the bottom through the tuyeres.

The term “charge” refers to the materials fed at the top and includes the fuel, the ore and the flux.

The blast-furnace is a circular shaft of varying dimensions made of fire brick. The furnace has cylindrical crucible at its base for the molten products to be collected. The diameter of the shaft is the biggest in the zone of fusion. Chemical reactions between carbon, oxygen, and iron and its oxides occur within the blast-furnace. As a result of these reactions pig iron and slag are produced.

The cupola is a small blast-furnace used to remelt pig iron for the purpose of making iron castings in the foundry.

Cupola Melting. Most of the gray cast iron produced in this country is melted in the cupola furnace. The cupola is a vertical cylindrical type of furnace, consisting of a steel shell lined with firebrick. Usually the charging door is located 15 to 25 ft above the bottom plate. At the lower end of the furnace is a wind box or air box. Air enters the cupola openings called tuyeres. Some cupolas are equipped with a single row of tuyeres; others have an auxiliary upper row of tuyeres. Opinion is divided as to whether a single or a double row is more desirable. A patented cupola known as the “balanced blast cupola”, developed by the British Cast Iron Research Association, has three rows of tuyeres. A number of furnaces of this type have been instal­led in this country.

The cupola is a simple and economical melting unit, because the fuel and the metal are in intimate contact with each other. Fuel, metal and flux enter the cupola through the charging door. The initial charge of coke is known as the “bed charge”. The metal is deposited on the coke. Then alternate layers of coke and iron are added.

Generally a flux is charged on the coke and the coke bed ignited by means of kindling wood or an oil torch. This bed usually extends from 36 to 60 in. above the top of the lower tuyeres. The make up of the charge and the charging are most important in obtaining uniform results in melting.

to constitute, to be capable, to produce, pig iron, large quantities, raw materials, to consist of, iron ore, limestone, fuel, to be forced into, passage, combustion gases, to blow, bottom, charge, to feed, to include, flux, blast-furnace, varying dimensions, fire brick, cylindrical crucible, molten products, to occur, slag, cupola, to remelt, castings, foundry, wind box, single row, " bed charge", coke, alternate layers, to add, kindling wood, oil torch, uniform results, melting.

equip produce blow include charge locate melt

1. Blast furnace _____ more than one thousand tons of pig iron a day.

2. The charge _____ the fuel, the ore and the flux.

3. Usually the air _____ in the bottom through the tuyeres.

4. Most of grey iron _____ in the cupola.

5. The charging door of the cupola _____ 15 - 25 ft above the bottom plate.

6. Some cupolas _____ with a single row of tuyeres; others - two or three rows.

7. A flux _____ on the coke.

1. What is the most complicated type of metallurgical plant?

2. List the materials entering the blast furnace.

3. How many tons of pig iron is the blast furnace capable to produce?

4. Give a detailed description of the blast furnace.

5. Give a detailed description of the cupola.

Words and word combinations to be memorized:

паливо, заливатися розплавленим, чавун, домна, утворювати шлак, прокат і кування, виливниця, вогнетривка цегла, нахилена ємність, глина, розплавлений метал, отвори, готова сталь, верхівка конвертера, дуплексна сталь, додатково очищати, оксид заліза, ківш, видалення вуглецю, мартенівська піч.

In the Bessemer process no fuel is used. The pig iron from the blast-furnace is poured molten into the converter, and a strong blast of air is sent up through it. The air first oxidises the silicon and manganese, which, together with some iron oxide, rise to the top and form a slag. The blowing is continued until the carbon content is lowered to about 0.05%. When the blow is completed the amount of carbon necessary to bring the carbon content to the specified percentage, together with manganese to counteract the influence of sulphur, and silicon to degasify, are added to the molten metal. The finished steel is then poured into a ladle, and hence it is poured into the ingot molds for subsequent rolling or forging.

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 there 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 considered to be inferior to steel produced by other methods. It is still used because of low cost of its production, 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.

Bessemer steel refined additionally in the open-hearth, or electric furnace, is called duplex steel.

to oxidize, to refine additionally, to charge, to discharge, to accomplish the stage, reddish-brown fumes, to emit a deep roar, low cost of production, to counteract, steel plates, vessel, ruddy flames, silicon, the amount of carbon, to pour the molten iron, the blast of air, dense cloud, low cost of production, steel plates, to be charged and discharged.

to pour, to refine, to consider, to continue

to oxidize, to use, to pour, to send, to add

1. The pig iron from the blast-furnace _____ into the converter, and a strong blast of air _____ up through it.

2. The air _____ the silicon and manganese, which, together with some iron oxide, rise to the top and form a slag.

3. The blowing _____ until the carbon content is lowered to about 0.05%.

4. Then some amount of carbon, manganese, and silicon _____ to the molten metal.

5. The finished steel _____ into a ladle.

6. Bessemer steel _____ to be inferior to steel produced by other methods.

7. Bessemer steel _____ because of low cost of its production, cost of the process.

8. Bessemer steel _____ additionally in the open-hearth or electric furnace.

1. Розплавлений метал заливається в конвертер, а потім продувається повітрям.

2. До вуглецю додається марганець з метою нейтралізації дії сірки.

3. Сталь можливо виготовити за допомогою складного Бесемерівського процесу.

4. Бесемерівський процес складається з підготовки шлаку, очищення, та видалення вуглецю.

Ø to use fuel

Ø to pour molten pig iron

Ø to send air through, to oxidize silicon and manganese, to form a slag

Ø to continue the blowing, to lower the carbon content

Ø to add the amount of carbon, silicon, and manganese

Ø to pour the finished steel (into a ladle, into the ingot molds)

Task 9. Make up 7 questions to the text “Bessemer process”.

Words and word combinations to be memorized:

прямокутна й досить низька, мілка ванна, склад, плавлення, очищення, обкладений вогнетривкою цеглою, складатися з, червоний залізняк, додаватись, попередньо нагріте повітря, легуючі елементи, завантаження, вимагати постійного нагляду, шкідливі домішки, випускати (сталь), нержавіюча й жаростійка сталь, переваги, плаский купол, додаткове очищення, тигельний процес, правильний склад, плавлення, розкислення, очистка, витримувати високі температури, чавун у чушках, металолом, легуючі елементи, шар, бокові стіни.

The open-hearth furnace is rectangular and rather low, holding from 15 to 200 tons of metal in a shallow pool. The purpose of this furnace is to convert various types of ferrous material into finished steel of proper composition and quality. The open-hearth process is a very versatile one, for it involves melting, refining and dioxidation.

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.

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.

Electrical furnaces are used in making high-grade steels from cold material; they are also used in additional refining of steel produced by the Bessemer and open-hearth processes. The electric furnace is now capable of making high-grade tool steels equal in quality to the steels produced by crucible process.

open-hearth furnace, to convert, ferrous material, quality, to involve, the hearth of the furnace, flames, to melt the steel, to withstand, charge, scrap, lime, steel desired, to locate, along with, occur, freely, ladle, to impart, generate, precise control, be regulated at will, resembling a huge tea-kettle, side walls, roof, to be shaped, to carry the current, high-grade steels, a strong blast of air, to form a slag, the specified percentage, rolling or forging, tilting vessel, clay, a shower of sparks, reddish-brown fumes, the refining action, proper composition and quality, the hearth of the furnace, to fa­cilitate combustion, the process of charging, melting down process, the period of refining, a circular steel shell, to be tilted to pour off molten metal and slag, refractory bricks, crucible process.

1. production, used, heat, The electric, is, stainless, for, and, resistant, of, furnace, steels.

2. is, because, The open-hearth, more, is, it, frequently, used, control, easier, process, to.

Task 5. Match the words in column A with their meanings from column B.

1. При виготовленні сталі Бесемерівським процесом паливо не застосовується.

2. Спочатку йде обробка, а потім готова сталь виливається в ківш.

3. Перетворювач обкладено вогнетривкою цеглою та глиною.

4. Після закінчення треба зменшити потік повітря та вийняти готову сталь.

5. Мартенівська піч використовується для перетворення чорних метал на сталь.

6. Піч працює при високих температурах, тому вона обкладена вогнетривкою цеглою.

7. Один з етапів роботи печі це процес очищення.

8. Сьогоднішні технології дозволяють підтримувати процес згоряння без використання кисню.

precise control, heat, heat resistant, ladle, method,

atmosphere, furnace, advantages, temperatures, steels

1. The finest grades of steel are produced by the electric furnace _______.

2. Stainless and _______ steels are made almost exclusively by that process.

3. Electricity is used only for the production of ______.

4. The electric furnace method gives certain _______ impossible in other melting processes.

2. The electric furnace generates extremely high _______.

3. The temperature is at all times under _______ and is easily regulated.

4. Electrical furnaces are used in making high-grade _______ from cold material.

5. The _______ within an electric furnace may be regulated at will.

1. What is the open-hearth furnace?

2. What is the purpose of the open-hearth furnace?

3. What were the reasons for the name “open-hearth”?

4. List the features of the open-hearth process?

5. Give the description of the open-hearth furnace and list the components of its charge.

6. Describe the stages of the open-hearth process.

7. What is the purpose of the electric furnace?

8. List the features of the electric furnace.

9. Give a description of the electric furnace.

10. Where is the electric furnace used?

Words and word combinations to be memorized:

To produce ferrous metals one must combine iron with carbon, silicon, other elements. 1) ___D___ Ferrous metals are used in industry in two general forms: steel and cast iron, which differ in the quantity of carbon content. These two ferrous alloys are derived from pig iron which is produced in a blast furnace in form of pigs. Metals are usually melted and poured into a form which is called a " mould". 2) _______ The cast metal is shaped in the mould where it cools and solidifies. Thus one can cast different objects known as castings. The shop where metals are cast is called a " foundry". Castings are used to produce different types of machinery.

Steel is a ferrous material with a carbon content from 0.1% to 1.0%, which makes it much stronger than iron and is therefore widely used in machine building. 3) _______ Therefore the carbon content in steel is confined to certain limits. Semisteel is a name to a metal made by melting 20 to 40% of steel scrap with cast iron in the cupola. Steel castings are more expensive but stronger and tougher.

Cast steel normally contains about 0.5% of carbon, and is used to replace cast iron when castings of considerable strength are required.

Forged steel is steel that has been hammered, drawn, pressed or rolled in the process of manufacturing of a particular part.

Alloy steels are those in which some alloying element in addition to the carbon is present in some appreciable quantity. The principal alloying elements used in steel are nickel, chromium, vanadium, molybdenum, manga­nese, and to lesser extent, copper, tungsten, cobalt, beryl­lium and boron.

Cast iron contains a higher percentage of carbon than steel does (more than 2.0 %). 4) _______. Cast iron without the addition of alloying elements is weak in tension and shear, strong in compression and has low resistance to impact. It is obtained from the cupola furnace where pig iron is remelted in contact with coke.

Grey cast iron has the carbon present in the free or graphite state and is soft, easily machined, and only moderately brittle.

White cast iron has most of the carbon in the combined state and is therefore hard and brittle.

Malleable cast iron is made by heating white iron castings for a period of several days in airtight pots filled with an oxide of iron. 5) _______.

Grey iron foundries are the most numerous because grey iron can be cast into almost any conceivable shape and size. Grey iron is also adapted to a great variety of castings, such as automobile, gas, steam, and hydraulic engine cylinders, bed plates for machines, car wheels, agricultural machinery parts, furnace and stove parts, water pipes, gears, etc. The nature of the metal used for grey iron castings is such that castings can be made so hard that ordinary tool steel will not cut them or, on the other hand, so soft that they can be readily-machined. 6) _______. The alloy of grey castings is composed of iron, carbon, silicon, phosphorus, manganese, and sulphur. These elements are used in different proportions depending on the grade of castings.

There is one more kind of ferrous materials - wrought iron. It is quite ductile and can be easily rolled, drawn, forged and welded. 7) _______. The carbon content is generally less than 0.1% and the material must contain not less than 1% slag.

кількість, вміст вуглецю, чушки, мульда, затвердівати, цех, крихкий, ливарний цех, обмежувати, вагранка, межа міцності, легована сталь, кокс, сплав, колізія, сірий чавун, дешевий, необхідні форма та розмір, опорні плити, труба, шестерня.

ferrous alloys, the quantity of carbon content, a blast furnace, melted and poured into, to cool and solidify, casting, brittle, weak in tension and shear, easily machined, airtight pots, stove parts, water pipes, soft, grade of castings, to be rolled, drawn, forged and welded.

to consist, to form, to have, to restrict

1. The cast metal _______ in the mould where it cools and solidifies.

2. The carbon content in steel _______ to certain limits.

3. Cast steel normally ______ about 0.5% of carbon.

4. The alloy of grey castings ________ of iron, carbon, silicon, phosphorus, manganese, and sulphur.

1. Вміст вуглецю допомагає визначити чорний метал.

2. Сталь та чавун виготовляються в доменних печах.

3. Метал плавиться та заливається в мульду, де він охолоджується та затвердіває.

4. Виливки виготовляються в ливарному цеху, а потім використовуються в різних видах машинного обладнання.

5. Сталь широко використовується в машинобудування оскільки вона міцніша за залізо.

6. Легована сталь містить в собі, окрім вуглецю, ще деякі легуючі елементи.

7. Чавун виготовляється в мартенівських печах з заліза в чушках.

8. Автомобільні колеса, газові та парові двигуни, труби та шестерні виготовляються з сірого чавуну.

brittle, to heat, weaker, cooling, scanty

Words and word combinations to be memorized:

Non-ferrous metals are more expensive than ferrous metals and are used only when some characteristic not possessed by iron or steel is essential or desirable in application. 1) A.

The metals most frequently used to make non-ferrous metal castings are copper, tin, zinc, nickel, gold, aluminium and lead. Some of the basic non-ferrous metals and their characteristics are described below.

Copper was used in prehistoric times for making weapons and tools and later was alloyed with tin to form bronze, which was the most important metal of the Greeks and Romans. 2) _______. Various grades of copper are used for engineering purposes. The great development of the electric industries has resulted in such extensive uses of the metal that it now ranks next to iron in importance.

We know copper to be a reddish-brown tough metal. Among non-ferrous metals copper is the most important. Because of its high electric conductivity about 60 % of all the copper produced is used in electrical work. It has high corrosion-resistant qualities. 3) _______.

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 anti-friction properties in others.

Aluminium is the typical metal in the third group in the periodic clas­sification of the elements. 4) _______. It is found in feldspars, micas, kaolin, clay, bauxite, cryolite, alunite, corundum and certain gems. Compounds of aluminium have been known for many years and they were recognised as being derived from a metal that had not been isolated. 5) _______. It is light in weight, has high corrosion-resistant qualities. Scientists suggest aluminium to be used for automobile and airplane parts. It can be used also for making different light-weight objects used in everyday life such as: frames, cooking utensils, chairs.

Aluminium has a very low density, 2.7; it is used in construction when a metal is required and weight is important. It is ductile, malleable, and can be rolled. Its tensile strength is low in comparison with that of iron; it cannot be machined and polished readily and does not yield good castings. These defects can be overcome by alloying it with other metals. The metals which alloy freely with aluminium are copper, zinc, and iron. Usually where aluminium alloys are made, aluminium predominates. 6) _______.

Zinc is a hard, brittle, bluish-white metal that is employed in the pure form as sheet zinc.

Lead is a very heavy bluish-grey metal which is very soft. We know lead to be supported by a core to strengthen it. Lead is used for lining pipes, acid tanks and coating electrical cables.

Tin is a silvery, corrosion-resistant metal. We suggest tin to be used as an alloying element. Tin is hardly used in pure form.

Nickel is a hard, tough, silvery metal. 7) _______.

There are many applications of non-ferrous metals in the unalloyed state, but in most cases, some alloying element is added.

електро- та термопровідність, корозійностійкий, олово, свинець, зброя, польовий шпат, слюда, глина, м’який, вага, межа міцності на розтягнення, у порівнянні з золотом, легко сплавляється, дроти, провідник, чиста форма, труби, міцний.

more expensive, desirable in application, non-magnetic qualities, light weight, most frequently used, metal castings, making weapons and tools, engineering purposes, extensive uses, the anticorrosive and anti-friction properties, the most abundant of the metals, the most widely distributed, automobile and airplane parts, ductile, malleable, unalloyed state.

to show, to possess, to give rise to, to beat

1. Copper _______ high corrosion-resistant qualities

2. These defects _______ by alloying it with other metals.

3. Some of the basic non-ferrous metals and their characteristics _______ below.

4. The great development of the electric industries _______ such extensive uses of the metal that it now ranks next to iron in importance.

1. Кольорові метали використовуються через їх фізичні властивості, такі як: корозійна стійкість, тепло- та електропровідність та інші.

2. Люди сплавили мідь з оловом, щоб утворити бронзу.

3. Мідь використовується для виготовлення дротів, електричних контактів, нагрівачів води, і т.п.

4. В автомобільній промисловості та літакобудуванні конструктори використовують алюміній через його легку вагу та антикорозійні властивості.

5. Олово найчастіше використовується як легуючий елемент.

6. Кольорові метали дуже рідко використовуються в чистому вигляді, дуже часто додається який-небудь легуючий елемент.

to consist, to form, to have, to restrict

1. The cast metal _______ in the mould where it cools and solidifies.

2. The carbon content in steel _______ to certain limits.

3. Cast steel normally ______ about 0.5% of carbon.

4. The alloy of grey castings ________ of iron, carbon, silicon, phosphorus, manganese, and sulphur.

1. Iron, like most metals, (to find) in the Earth's crust in an elemental state.

2. If a piece of copper (to heat) it becomes coated in black copper oxide.

3. Tensile strength (to measure) in units of force per unit area.

4. A malleable metal easily (to deform), especially by hammering or rolling, without cracking.

5. Hardness (to measure) on the Mohs scale or various other scales.

6. Blast furnaces (to use) for non-ferrous smelting processes, particularly in the production of lead.

Words and word combinations to be memorized:

певні характеристики, змінювати форму, зовнішні сили, обробляти, тривалість, пружність, згинання, прилад, примірник, показник ступеня гнучкості, властивість, зберігати, визначення пластичності металу, покращувати властивості металу, тепло обробка, охолодження.

Properties of engineering materials are known to affect manufacture and application of them. While using engineering materials we must know their physical characteristics. All engineering materials have definite characteristics which determine their abilities to assume external loads because of which materials change their shape. Metals are known to be subjected to the influence of external forces when they are treated. These forces are called " loads" and may have different characteristics: according to their value they may be small or large; according to the duration and character of their action they may be constant and impact. According to the influence of the load upon the metal causing different changes of its shape, loads are distinguished as compression, tensile, torsion, shearing and bending ones. By testing a metal under a load one can define what mechanical properties it has. In order to have a clear conception of the metal properties it is subjected to tests on special devices and machines. The determination of these properties is made in the laboratory using a specimen of the metal to be tested.

In studying engineering processes an engineer who is to build a machine must select suitable materials for each machine member. One must know the characteristics of engineering materials. These are as follows: strength, stiffness, ductility, toughness, elasticity, plasticity, fatigue resistance, shock resistance, corrosion resistance, wear resistance, hardness, frictional qualities, machinability, casting and forging properties. They depend upon the chemical composition and the physical structure of the material.

Strength is the property of hard materials to be subjected to the influence of external forces without incurring damage, without changing their shape. The ultimate tensile strength of a material is that unit stress developed in the material by maximum slowly applied load that material can resist without rupturing in a tensile test.

Special machines, called " rupture machines", are used to test metals for strength. When testing a specimen, the upper clamp remains fixed and the lower one is being slowly lowered, thus causing the extension of the specimen. The load upon the specimen may be easily determined at any moment by means of pointer indications on the dial.

Elasticity is the ability of a material to change its shape under the influence of external loads and return to its original form upon removal of the loads. All materials are elastic but the range of elasticity varies for different materials. Elasticity is evaluated by means of the modulus of elasticity. The modulus of elasticity is considered to be the ratio of the unit stress to the unit deformation within the proportional limit of the material to be tested. A rupture machine may be used to determine the elasticity of metals.

Plasticity is the property of a material when under the influence of loads, specimens of different materials may elongate while their cross-section decreases. Plasticity is the opposite of elasticity. So, plasticity is the ability of material to change its form without breaking under the influence of load and preserve this changed form after removal of the load. For determining the plasticity of metals a rupture machine may be used too.

There are some processes changing and improving the properties of metals. Heat-treatment is the process of controlled heating and cooling of metals to change their structural arrangement and to ensure certain desirable properties. Annealing consists of heating the metal to a temperature slightly above the critical temperature and then cooling slowly to produce an even grain structure, reduce the hardness, and increase the ductility. Normalising is a form of annealing in which the material is cooled in the air. Quenching or rapid cooling from above the critical temperature by immersion in bold water or some other cooling medium is a hardening treatment. Tempering consists of reheating