I. Text A: «Metals», Text B: «Steel», Text C: «Methods of steel heat treatment»




II. Famous Scientists. Dmitry Ivanovlch Mendeleyev.

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 andbent withoutfrac­ture) 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 resist corro­sion. 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)





©2015-2017 poisk-ru.ru
Все права принадлежать их авторам. Данный сайт не претендует на авторства, а предоставляет бесплатное использование.
Нарушение авторских прав и Нарушение персональных данных

Обратная связь

ТОП 5 активных страниц!