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STEEL AND METHODS OF STEEL HEAT TREATMENT





сarbon –вуглець corrode – ржавіти rusting – ржавіння stainless– нержавіючий resist – опиратися tough – міцний, жорсткий core – серцевина, середина blade –лезо   spring – пружина inclusion – включення affect– впливати silicon– кремній rust-proof – той, що не ржавіє case-hardening – зміцнення цементуванням tungsten – вольфрам  

 

The most important metal in industry is iron and its alloy – steel. Steel is an alloy of iron and carbon. It is strong but corrodes easily through rusting, although stainless and other special steels resist corrosion. The amount of carbon in steel influences its properties considerably. Steels of low carbon content (mild steels) are quite ductile and are used in the manufacture of sheet iron, wire and pipes. Medium-carbon steels containing from 0.2 to 0.4 per cent carbon are tougher and stronger and are used as structural steels. Both mild and medium- carbon steels are suitable for forging and welding. High-carbon steels contain from 0.4 to 1.5 per cent carbon, are hard and brittle and are used in cutting tools, surgical instruments, razor blades and springs. Tool steel, also called silver steel, contains about 1 per cent carbon and is strengthened and toughened by quenching and tempering.

The inclusion of other elements affects the properties of the steel. Manganese gives extra strength and toughness. Steel containing 4 per cent silicon is used for transformer cores or electromagnets because it has large grains acting like small magnets. The addition of chromium gives extra strength and corrosion resistance, so we can get rust-proof steels. Heating in the presence of carbon or nitrogen-rich materials is used to form a hard surface on steel (case-hardening). High-speed steels, which are extremely important in machine-tools, contain chromium and tungsten plus smaller amounts of vanadium, molyb­denum and other metals.

Methods of steel heat treatment:

Quenching is a heat treatment when metal at a high temperature is rapidly cooled by immersion in water of oil. Quenching makes steel harder and more brittle, with small grains structure.

Tempering is a heat treatment applied to steel and certain alloys. Hardened steel after quenching from a high temperature is too hard and brittle for many applications and is also brittle. Tempering, that is reheating to an intermediate temperature and cooling slowly, reduces this hardness and brittleness. Tempering temperatures depend on the composition of the steel but are frequently between 100 and 650'C. Higher temperatures usually give a softer, tougher product. The colour of the oxide film produced on the surface of the heated metal often serves as the indicator of its temperature.

Annealing is a heat treatment in which a material at high temperature is cooled slowly. After cooling, the metal again becomes malleable and ductile (capable of being bent many times without cracking).

All these methods of steel heat treatment are used to obtain steels with certain mechanical properties for certain needs.

Ex. 17. Answer the questions:

1. What is steel?

1. What are the main properties of steel?

2. What are the drawbacks of steel?

3. What kinds of steel do you know? Where are they used?

4. What gives the addition of manganese, silicon and chromium to steel?

6. What can be made of mild steels (medium-carbon steels, high-carbon steels)?

7. What kind of steels can be forged and welded?

8. How can we get rust-proof (stainless) steel?

9. What is used to form a hard surface on steel?

10. What are high-speed steels alloyed with?

11. What can be done to obtain harder steel?

12. What makes steel more soft and tough?

13. What makes steel more malleable and ductile?

14. What can serve as the indicator of metal temperature while heating it?

15. What temperature range is used for tempering?

16. What are the methods of steel heat treatment used for?

 

Ex. 18. Find the following words and word combinations in the text B:

1. Сплав заліза та вуглецю

2. Міцний та жорсткий

3. Легко корозують

4. Нержавіюча сталь

5. Низький вміст вуглецю

6. Ковкість

7. Листове залізо, проволока, труби

8. Конструкційні сталі

9. Підходять для ковки та зварювання

10.Твердий і крихкий

11.Ріжучі інструменти

12.Хірургічні інструменти

13.Інструментальна сталь

14.Додавання марганцю (кремнію, хрому, вольф­раму, молібдену, ванадію)

15.Зміцнювати

16.Температурна нормалізація

17.Мілкозерниста структура

18.Швидке охолодження

19.Склад сталі

Unit 11

Text A. Liquids Text B. The Electrical Properties of Materials Grammar:The Gerund The Emphatic Construction

Text A

 

LIQUIDS

Shape– форма Layer– шар, пласт Dense – густий; щільний Disturb– турбувати, порушувати Flow– потік Viscous– в'язкий Viscosity– в'язкість Fluidity –текучість Average– середній Velocity– швидкість Escaping– вихід, випуск, витік

The liquid state occupies an intermediate position between the gaseous and solid states, liquid having a definite volume but no definite shape.

Like a gas, a liquid can take the shape of any vessel in which it is put, but in contrast to a gas, a definite quantity of liquid is required for filling the vessel. A liquid can't be compressed so much as a gas because its molecules are already close together, large pressure producing small changes in volume.

Increasing in temperature increases the kinetic energy of all molecules.

The change of a liquid into the gaseous or solid states being dependent upon the kinetic energy of the molecules, which in turn is dependent upon the temperature, there are definite temperature characteristics for most liquids at which these changes occur. They are known as transition temperatures.

If we place one liquid layer carefully on top of a layer of a more dense liquid in which it is soluble, and set the vessel where it won't be disturbed, we shall see that two liquids begin gradually mixing. It is also to be taken into consideration that all liquids do not flow with the same ease, water, alcohol, gasoline flowing easily, while heavy oil, glycerin flowing very slowly.

When a liquid flows, layers of molecules begin rubbing over each other, friction being generated by this rubbing of layers of particles. The greater the friction, the slower is the flow. A liquid, which resists flowing, or resists the action of any other deforming force upon it, results in a homogeneous solution. We give this example for illustrations that the molecules of a liquid diffuse, though much more slowly than do those of a gas.

The molecules of a liquid are much closer together than they are in a gas, because of the greater relative strength of attraction, the density of liquids being much greater. Naturally as the volume of a liquid begins varying with temperature its density will also start varying with temperature.

It should be noted that the closeness of the molecules also is known as viscous, the opposite of viscosity being fluidity. Viscosity diminishes and fluidity increases with temperature.

Evaporation

The molecules within the interior of a liquid have a definite average energy of motion, and thus a definite mean velocity at each temperature. Some of them, however, at any given instant have a velocity sufficiently greater than the average velocity and this enables them breaking through the surface layer of molecules and escaping. Escaping of molecules from a liquid into its vapour is called evaporation.

 

Ex.1. Answer the following questions:

1. What position does liquid state occupy? 2. What shape does liquid take? 3. Is it possible for a liquid to be compressed? 4. Why is it impossible? 5. What does the change of a liquid into the gaseous or solid states depend on? 6. What will happen if we place one liquid layer on top of a layer of a more dense liquid in which it is soluble? 7. Do all liquids flow with the same ease? 8. What is the friction generated by? 9. Why are the molecules of a liquid much closer together than
those of a gas? 10. What is evaporation?

 

Ex. 2. Translate the following sentences paying attention to the meanings of the words in bold type:

1. The temperature of the sun is intensely high. 2. This substance is highly insoluble in water. 3. The increase of energy stored in the gas, because of the rise in temperature, is called the increase of internal energy. 4. Solids that conduct
heat readily are called good conductors. 5. This reaction should be watched closely because it is very important for the final results. 6. If you close this container, the reaction will stop. 7. A solid body has a definite shape, its molecules acting as though they were closely bound to one another. 8. It is very important to remember that melting occurs without any change in temperature. 9. Any change in temperature influences the pressure. 10. The closer we bring two charged bodies together the more attraction or repulsion they will exercise on each other.

 

Ex. 3. Translate the following sentences paying attention to the meanings of "any":

1. At any temperature the molecules of gases can have the same kinetic energy. 2. Any body when heated to a sufficient high temperature becomes a source of light. 3. There is hardly anybody who doesn't know this law. 4. In any chemical compound the algebraic sum of the valence charges, or numbers, must be zero. 5. Give us any book on the history of Ukrainian culture. 6. Have you got any new devices in your laboratory? 7. They couldn't get any articles dealing with the development of rubber industry. 8. Any student who is interested in research work can take part in the work of our scientific society. 9. Many of the metals occur more extensively in silicates than in any other compounds, but the silicates are not used so extensively as ores because of difficulties involved in the production of the metals. 10. The classification of a particular element as a metal is based on a consideration of all its properties rather than any single property. 11. Having entered the laboratory, I couldn't see anybody at first as it was very dark there. 12. This substance is to be purified before using, at any rate.

 

Ex. 4. Find the pairs of antonyms and remember them:

Rapidly, liquid, definite, decrease, solid, indefinite, increase, ease, heavy, difficulty, light, slowly.

 

Ex. 5. Translate the sentences, mind the use of "for":

1. This new machine has been working for twelve hours without stopping. 2. This semiconductor was used for the first time at our plant. 3. The use of charcoal and other adsorbents for the removal of impurities from a substance in solution has long been common practice. 4. For this reason this material couldn't be used as a conductor. 5. There is one use for which the carbon lamp suits better than the tungsten lamp. 6. Photoelectric cells are known to be used for detecting flaws in certain products. 7. For centuries glass was used for jewelry, ornaments and mosaic.

 

Ex. 6. Remember the meaning of the following words:

feature – риса, особливість

future – майбутнє

thorough – ретельний, грунтовний

through – через

low – низький

law – закон

 

 

Ex. 7. Translate the following sentences according to the model:

Model: The higher the temperature, the greater is the amount of heat evolved.
Чим вищa температура, тим більшa кількість тепла, що виділяється.

1. The stronger the acid, the greater is the tendency to lose protons. 2. The stronger the magnification, the greater is the possibility to detect whether the body is homogeneous. 3. The faster an object moves, the greater is the air resistance. 4. The lower the atomic weight or atomic number of the inert gas, the lower are its boiling and melting points. 5. The larger the diameter, the smaller is the resistance and hence, the more current will flow through it. 6. The greater the difference in temperature between two points, the more heat will flow per second. 7. The greater the number of free electrons in a substance, the better that substance is a conductor of electricity.

 

Ex. 8. Translate the following sentences:

1. It is this article that shows the progress of our industry. 2. It was D. I. Mendeleyev who first classified the elements according to their atomic weights. 3. It is the development of chemical processes that his report deals with. 4. It was not until 1911 that the first theory of atomic structure was suggested 5. It was the Dutch physicist, Christian Huygens, who offered an explanation for this new phenomenon.

Ex. 9. Translate the following sentences:

1. Though these molecules are very small the examination under a very powerful electronic microscope may show that they do exist. 2. He did carry out this experiment without any outside help. 3. Water does dissolve some substances readily. 4. This metal does conduct electricity well. 5. Though this subject was very difficult for him he did master it well. 6. All of the weight relations in chemical reactions do depend upon the weights of the atoms of the elements. 7. The process of extraction does involve four steps. 8. These electrode reactions, like other chemical reactions, do occur in steps. Ido know this man very well.

 

GRAMMAR

 

The Gerund

Study and remember the following chart:

  ACTIVE PASSIVE
INDEFINITE asking being asked
PERFECT having asked having been asked

 

1. Before leaving the laboratory he cleaned his labo­ratory bench. 2. After finishing his work he left the Institute. 3. His work resulted in discovering this new pheno­menon

Ex. 10. Change the following sentences as in the models:

Model I: He will wash glassware before he leaves. He will wash glassware before leaving.

1. We shall discuss this plan before we begin our work. 2. Before I translate the article Ishall read it thoroughly.

Model II: After school he began to attend high courses. After school he began attending high courses.

1. As he was tired he stopped to read the report and left for home. 2. They started to make experiments in the second year. 3. They finished to look through the papers as soon as they had found the article concerned. 4. As I am very busy I can't continue to attend these lectures.

Model III: When he came into the laboratory he came up to me. (on)

On coming into the laboratory he came up to me.

1. You can get better results if you repeat the analysis. (by) 2. He will be able to translate the article after he repeats all the words, (after) 3. When he leaves the office he usually locks the door, (on) 4. Excuse me that I came so late, (for)

Ex. 11. Use the Gerund of the verbs in brackets:

1. On (to get) good results he will inform me. 2. He succeeded in (to find) the book he needed. 3. His work resulted in (to discover) new elements.

Ex. 12. Translate the sentences, mind the Gerunds:

1. Solid bodies have the property of keeping their shape without supporting of a vessel. 2. Upon being heated, the molecules begin moving very quickly. 3. If two glass rods are charged by rubbing them with silk, it is possible to watch a very interesting phenomenon. 4. Without being treated thissubstance cannot be used. 5. At last our research-workers succeeded in getting good results. 6. The teacher insists on carrying out this experiment in our laboratory. 7. Upon carrying out a number of experiments our students solved many interesting problems. 8. By using this law we define a unit charge of electricity. 9. Heating the wire from 0° to 100° increases its resistance approximately by 40%. 10. This experiment shows the increase of reaction velocity with increasing temperature.

Ex. 13. Replace the Subordinate Clauses by the Gerund according to the models:

Model I: After the student carried out his experiment he cleaned the laboratory bench. After carrying out his experiment the student cleaned the laboratory bench.

 

Model II: When they had finished their experimental work, they could write the report. After having finished their experimental work, they could write the report.

1. When they passed their last examination, they came to me. 2. After they had purified the water they could use it for drinking. 3. Before he began the translation of that article he had read it twice.4. When he discovered that new phenomenon he told us about it at once. 5. Before he left he had prepared everything for us.

Ex. 14. Translate the sentences, mind the Gerund and Gerundial Constructions:

1. One of the most common methods of dissolving precipitates is their chemical conversion into soluble products.2. Besides finding out the type of a given reaction a chemist wants to know what products of the reaction he'll receive. 3. After being recrystallized from ethyl alcohol the solid be gan melting. 4. In writing formulas, the symbol for the more positive element is written first, as in NaCl. 5. After having investigated this strange phenomenon they succeeded in solving this problem. 6. It is because of this reaction with water that sodium must be protected from the moisture of the air by being kept under kerosene. 7. You should stop speaking at the lectures. 8. We know of the new laboratory having been built in our Institute.

 

Ex. 15. Translate the following sentences, mind the "ing"-forms:

1. After melting, the average speed of the moleculesremains the same as before but the molecules are now free of each other. 2. The process of overcoming the attractive forces between the molecules of a substance is called melting. 3. The only difference between waves transmitting heat radiation and radio waves is the difference in the wave length. 4. Instead of increasing the temperature of the ice, the energy is used in decreasing the attraction between the ice molecules. 5. The temperature of the melted ice rising, the movement of its molecules is speeded up. 6. In the process of boiling heat is constantly added to the liquid. 7. When a liquid boils evaporation takes place throughout the volume of the liquid, small bubbles of vapour forming within the liquid. 8. By increasing the pressure, however, the substance can be obtained in a liquid state, provided the change from liquid to solid is accompanied by an expansion. 9. As we have seen, adding heat to a substance will not always cause a rise of its temperature. 10. It is only the fast moving molecules that are able to escape from a liquid surface. 11. When a liquid starts boiling at a certain temperature and under a given pressure, the heat causes the liquid to vaporize.12. Every liquid can have a definite vapour pressure, this pressure increasing with rising temperature. 13. The vapour pressure of a liquid becoming equal to atmospheric pressure, the liquid boils. 14. They succeeded in getting good resultsafter a number of tedious investigations. 15. The steam expanding its volume will increase. 16. This resulted in increasing' the temperature greatly. 17. The rate of evaporation also depends on evaporating surface. 18. Since gases expand on heating and contract on cooling, it is interesting toconsider, what will happen if we continue lowering their temperature. 19. A thermometer bulb exposed to direct sunlight becomes much hotter than the surrounding air. 20. Using a thermometer, it is possible to transform power at low voltage into power at high voltage, power at high voltage being also transformed into power at low voltage.

 

Ex. 16. Translate the following sentences, mind the words in bold type:

1. Having absorbed much heat, the aluminium when it is cooled can give up the same quantity of heat. 2. The energy lost by the hot water is equal to the energytransferred to the cold water. 3. The wire being very thin and the current being large, the amount of generated heat is greater than that in the thick wire. 4. The wire, being very thin, was very good for our experiment. 5. The melting point of pure iron is about 1,535°C, most steels melting at about 300 to 500°С. 6. A gas being heated at constant pressure, work is done by the gas when it expands. 7. The problem having been solved, we could go home.8. The vapour pressure of a solid at any temperature being greater than one atmosphere, the substance will pass directly from the solid to the vaporous condition. 9. A solid body having been melted, the change of state took place at a definite temperature. 10. Experiments using a constant source of heat show that heat must be supplied to melt the solid. 11.The quantity of heat required for the changing the unit mass of a substance from the solid to the liquid state without any change of temperature is called the latent heat. 12. The liquid, being lighter than mercury, rises. 13. The silicon atom, being only slightly heavier than the aluminium atom and a bit smaller in radius, is also very active. 14. Having four electrons in its outer level with light electrons in the next lower level, the atom may attain stability by either losing four lectrons or gaining four electrons. 15. The process of electrification is, therefore, not one of creating electricity but of transferring electrons from one material to another. 16. In passing through the metal electrons must collide with many ions. 17. In making up a condenser, one has to take into consideration its size, as the amount of charge that a condenser stores depends on its size.

 

Ex. 17. Translate the text using a dictionary. Analyse the "ing"-forms:

A liquid being cooled, its molecules lose energy. The cooling process being conducted slowly, the particles which constitute the solid may arrange themselves into definite positions. The solid itself will exist in a regular geometric form called a crystal. Crystals are of various forms and of varying degrees of strength and rigidity, both these properties depending upon the substance of which they are composed. Having learned this, we can state that the properties of matter in the gaseous state are determined largely by the motion of particles, while in the solid state they are determined largely by the rigidity of the structure formed and by the position which the particles occupy with respect to each other in the structure, these latter being dependent upon the magnitude of the forces of attraction and upon the size of the particles.

 

Ex. 18. Translate the following text analysing the functions of the Gerund:

A saturated solution of one of the numerous solids, which are more soluble at higher temperatures than at lower ones should, upon being cooled, deposit crystals of the solute until equilibrium is established at the lower temperature. If, however, the saturated solution at the higher temperature contains no undissolved solute and no particles of foreign matter, and if it is allowed to cool without being disturbed in anyway, it is often possible to cool it without crystallizing ofthe excess solute occurring. A solution which has been so cooled naturally contains more solute than can normally be dissolved in the given quantity of solvent at the existing temperature.

 

Text B







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