Text С: «METHODS OF STEEL HEAT TREATMENT»

Text A: «METALS»

Metals are materials most widely used in industry because of their properties. The study of the production andproperties of metals is known asmetallurgy.

Theseparation between the atoms in metals is small, so most metals aredense. The atoms arearranged regularly and canslide over each other. That is why metals aremalleable (can be deformed andbentwithoutfracture) andductile (can bedrawn intowire). Metals vary greatly in their properties. For example,lead is soft and can be bent by hand, whileiron can only be worked by hammering at red heat.

The regular arrangement of atoms in metals gives them a crystalline structure. Irregular crystals are called grains. The properties of the metalsdepend on thesize, shape, orientation, andcomposition of these grains. In general, a metal with small grains will be harder and stronger than one withcoarse grains.

Heattreatment such asquenching, tempering, or annealing controls the nature of the grains and their size in the metal. Small amounts of other metals (less than 1 per cent) are often added to a pure metal. This is called alloying (легирование) and it changes the grain structure and properties of metals.

All metals can be formed by drawing,rolling, hammering andextrusion, but some require hot-working. Metals are subject to metalfatigue and tocreep (the slow increase in length understress) causing deformation and failure. Both effects are taken into account by engineers when designing, for example, airplanes, gas-turbines, and pressure vessels for high-temperature chemical processes. Metals can be worked using machine-tools such as lathe, milling machine, shaper andgrinder.

The ways of working a metal depend on its properties. Many metals can bemelted andcast in moulds, but special conditions are required for metals that react with air.

Vocabulary:

property — свойство

metallurgy — металлургия

separation — разделение, отстояние

dense — плотный

arrangement — расположение

regularly — регулярно, правильно

to slide — скользить

malleable — ковкий, податливый, способный деформироваться

bent pp ofbend — гнуть

to fracture — ломать

ductile — эластичный, ковкий

to draw — волочить, тянуть

wire — проволока

lead — свинец

iron — железо, чугун

grain — зерно

to depend — зависеть

size — размер, величина

shape — форма, формировать

composition — состав

coarse — грубый, крупный

treatment — обработка

quenching — закалка

tempering — отпуск после закалки, нормализация

annealing — отжиг, отпуск

rolling — прокатка

to hammer — ковать (напр. молотом)

extrusion — экструзия

metal fatigue — усталость металла

creep — ползучесть

stress — давление,

failure — повреждение, разрушение

vessel — сосуд, котел, судно

lathe — токарный станок

milling machine — фрезерный станок

shaper — строгальный станок

grinder — шлифовальный станок

to melt — плавить, плавиться расплавить

to cast — отливать, отлить

mould — форма (для отливки)

General understanding:

1. What are metals and what do we call metallurgy?

2. Why are most metals dense?

3. Why are metals malleable?

4. What is malleability?

5. What are grains?

6. What is alloying?

7. What is crystalline structure?

8. What do the properties of metals depend on?

9. What changes the size of grains in metals?

10. What are the main processes of metal forming?

11. How are metals worked?

12. What is creeping?

Exercise 1.1. Find the following words and word combinations in the text:

1. Свойства металлов

2. расстояние между атомами

3. правильное расположение

4. сильно отличаются по своим свойствам

5. кристаллическая структура

6. размер зерен

7. форма зерен

8. закалка

9. отжиг

10.волочение

11.прокатка

12.ковка

13.экструзия

14. структура и свойства зерна

15. горячая обработка

16. усталость металла

17. ползучесть металла

18. плавка и отливка в формы

19. способы обработки металлов

Exercise 1.2. Complete the following sentences:

1. Metals are...

2. Metallurgy is...

3. Most metals are...

4. The regular arrangement of atoms in metals...

5. Irregular crystals...

6. The properties of the metals depend...

7. Metals with small grains will be...

8....controls the nature of the grains in the metal.

9. Alloying is...

10. All metals can be formed by...

11. Creep is...

12. Metals can be worked using...

Exercise 1.3. Explain in English the meaning of the following words:

1. malleability

2. crystalline structure

3. grains

4. heat treatment

5. alloying

6. creep

Exercise 1.4. Translate into English:

1. Металлы — плотные материалы потому, что между атомами в металлах малое расстояние.

2. Металлы имеют кристаллическую структуру из-за правильного расположения атомов.

3. Чем меньше зерна, тем тверже металл.

4. Закалка и отжиг изменяют форму и размер зерен в металлах.

5. Легирование изменяет структуру зерен и свойства металлов.

6. Металл деформируется и разрушается из-за усталости и ползучести.

Text В: «STEEL»

The most important metal in industry is iron and its alloy — steel. Steel is an alloy of iron and carbon. It is strong and stiff, but corrodes easily through rusting, although stainless and other special steels resistcorrosion. The amount of carbon in a 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.

Theinclusion of other elementsaffects the properties of the steel.Manganese gives extra strength and toughness. Steel containing 4 per centsilicon is used for transformercores or electromagnets because it has large grains acting like small magnets. The addition of chromium gives extra strength and corrosion resistance, so we can getrust-proof steels. Heating in the presence of carbonor 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 andtungsten plus smaller amounts of vanadium, molybdenum and other metals.

Vocabulary:

alloy — сплав

carbon— углерод

stiff — жесткий

to corrode — разъедать, ржаветь

rusty — ржавый

stainless — нержавеющий

to resist — сопротивляться

considerably — значительно, гораздо

tough — крепкий, жесткий, прочный, выносливый

forging — ковка

welding — сварка

brittle — хрупкий, ломкий

cutting tools — режущие инструменты

surgical instruments — хирургические инструменты

blade — лезвие

spring — пружина

inclusion — включение

to affect — влиять

manganese — марганец

silicon — кремний

rust-proof — нержавеющий

nitrogen — азот

tungsten — вольфрам

General understanding:

1. What is steel?

2. What are the main properties of steel?

3. What are the drawbacks of steel?

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

5. 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?

Exercise 1.5. Find the following words and word combinations in the text:

1. сплав железа и углерода

2. прочный и жесткий

3. легко коррозирует

4. нержавеющая сталь

5. низкое содержание углерода

6. ковкость

7. листовое железо, проволока, трубы

8. конструкционные стали

9. пригодны для ковки и сварки

10. твердый и хрупкий

11. режущие инструменты

12. хирургические инструменты

13. инструментальная сталь

14.упрочнять

15. добавление марганца (кремния, хрома, вольфрама, молибдена, ванадия)

Text С: «METHODS OF STEEL HEAT TREATMENT»

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

Tempering is a heat treatmentapplied 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 re-heating to anintermediate 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 color of the oxide film produced on the surface of the heated metal often serves as the indicator of its temperature.

Annealing isa 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 withoutcracking).

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

Vocabulary:

to immerse— погружать

to apply — применять

intermediate — промежуточный

oxide film — оксидная пленка

annealing — отжиг, отпуск

cracking — растрескивание

General understanding:

1. What can be done to obtain harder steel?

2. What makes steel more soft and tough?

3. What makes steel more malleable and ductile?

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

5. What temperature range is used for tempering?

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

Exercise 1.6. Translate into English the following words and word combinations:

1. температура нормализации

2. мелкозернистая структура

3. быстрое охлаждение

4. закаленная сталь

5. состав стали

6. окисная пленка

7. индикатор температуры

8. медленное охлаждение

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