Задание для студентов 205 группы на 25.12.2020

Задание 1. Прочитайте и переведите текст.

KINDS OF STEEL

There are two general kinds of steel: carbon steel and alloy steel. Carbon steel contains only iron and carbon, while alloy steel contains some other “alloying elements” such as nickel, chromium, manganese, molybdenum, tungsten, vanadium.

Each kind of steel is divided into several grades as follows:

1. Carbon steels.

a) low carbon steel containing from 0.05 to 0.15 per cent carbon; This steel is also known as machine steel;

b) medium steel containing from 0.15 to 0.60 per cent carbon;

c) high carbon steel containing from 0.6 to 1.50 per cent carbon; this steel is sometimes called “tool steel”.

2. Alloy steels.

a) special alloy steel, such as nickel steel, chromium steel;

b) high-speed steel also known as self-hardening steel.

Carbon steels are the most common steels used in. industry. The properties of these steels depend only on percentage of carbon they contain. Low carbon steels are very soft and can be used for rails, bolts and for machine parts that do not need strength.

Medium carbon steel is a better grade and stronger than low carbon steel. It is also more difficult to cut than low carbon steel.

High carbon steel may be hardened by heating it to a certain temperature and then quickly cooling in water. The more carbon the steel contains and the quicker the cooling is, the harder it becomes. Because of its high strength and hardness this grade of steel may be used for tools and working parts of machines.

But for some special uses, for example, for gears, bearings, springs, shafts, and wire, carbon steels cannot be always used because they have no properties needed for these parts. Some special alloy steels should be used for such parts because the alloying elements make them tougher, stronger, or harder than carbon steels.

Some alloying elements cause steel to resist rusting (corrosion), and such steels are called stainless steels. Stainless steels contain a high percentage of chromium. Chromium also makes steel harder. Nickel is used in steel to increase strength and toughness. Some alloying elements (such as chromium and tungsten make the grain of steel finer, thus increasing the hardness and strength of steel, because the finer the grain is, the stronger the steel becomes.

Heat-resistant steel is made by adding some tungsten and molybdenum, while manganese increases the wear resistance of steel. Vanadium steels resist corrosion and can stand shocks and vibration.

Tools made of high-speed steel containing tungsten, chromium, vanadium and carbon may do the work at much higher speeds than carbon tool steels.

Задание 2. Ответьте на вопросы к тексту. Ответы запишите в тетрадь на английском языке.

1. What are two general kinds of steel?

2. What is carbon steel?

3. What is an alloy steel?

4. What is the carbon content of medium-carbon steel?

5. Where are low-carbon steels used?

6. Where are high-carbon steels use?

7. What kind of steel can be hardened?

8. What steels are called stainless steels?

9. What parts are generally made of alloy steel?

10. Which alloying elements enable steel to resist trust?

Задание 3. Составьте план текста на английском языке и запишите его в тетрадь.

Задание 4. Поставьте глаголы, данные в скобках в правильную форму. Предложения запишите в тетрадь.

1. Metals (to use) by man after wood and stone.

2. Engineering metals (to use) in industry in the form of alloys.

3. Different metals (to produce) in different ways.

4. The first metal which (to produce) by people was copper.