3. Use the information from the text and complete the following table. C lassification of Engineering Materials

4. Define whether the following sentences are true or false.

1. Engineers must know the properties of engineering materials.

2. All materials can be classified as metals and non-metals.

3. Non-ferrous metals can contain iron.

4. Steels have to contain more carbon than cast iron.

5. Ceramics can resist high temperatures.

6. Thermosets may be machined.

7. Thermoplastics can be shaped and reshaped.

5. Answer the following questions.

1. What materials are used in engineering?

2. How are metals classified?

3. What’s the difference between ferrous and non-ferrous metals?

4. For what purpose are some elements (such as chromium and tungsten) added to steel?

5. What non-metals do you know?

6. What can you say about the classification and properties of plastics?

7. In what cases are ceramics used?

Metals

Word list:

metallurgy – металургія separation – відокремлення, відді-лення, роз'єднання; поділ; сепарація dense – щільний to arrange – розташовувати arrangement – розташування to slide – ковзати malleable – ковкий to bend (bent) – згинати(ся); гнути-(ся) fracture – тріщина ductile – гнучкий, ковкий to draw – тягти, волочити wire – дріт, провід to vary – різнитися, відрізнятися lead – свинець hammering – кування grains – зерна (металу) composition – утворення, побудова coarse – крупний, великозернистий heat treatment – термічна обробка

quenching – загартовування tempering – відпуск після загарто-вування, нормалізація annealing – відпалювання pure metal – чистий, бездомішко-вий метал alloying – легування drawing – волочіння rolling – прокатування extrusion – штампування видавлю-ванням hot-working – гаряча обробка subject – що підлягає (to) fatigue – втома (металу) creep – повзучість (металу) to cause – спричиняти, завдавати, викликати failure – пошкодження to melt – плавити(ся), розтоплюва-ти(ся)

Exercises to the subject:

1. Read the text and say why metals are widely used in industry.

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

The separation between the atoms in metals is small, so most metals are dense. The atoms are arranged regularly and can slide over each other. That is why metals are malleable (can be deformed and beat without fracture) and ductile (can be drawn into wire). Metals vary greatly in their properties. For example, lead is soft and can be bent by hand, while iron 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 metals depend on the size, shape, orientation, and composition of these grains. In general, a metal with small grains will be harder and stronger than one with coarse grains.

Heat treatment such as quenching, 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 the pure metal. This is called alloying and it changes the grain structure and properties of metals.

All metals can be formed by drawing, rolling, hammering and extrusion, but some require hot-working. Metals are subject to metal fatigue and to creep (the slow increase in length under stress) 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 and grinder.

The ways of working metal depend on its properties. Many metals can be melted and cast in moulds, but special conditions are required for metals that react with air.

2. Find the following words and word-combinations in English in the text: матеріали, які найбільш широко використовуються в промисловості; виробництво і властивості металів; мякий метал; кування у дуже розігрітому стані; повільне збільшення у довжину; поперечно-стругальний верстат; відливати у ливарні форми; особливі умови; контактувати з повітрям.