Rupture, creep, alternating, external, fatigue, original, exceed, torsion, subjected, tension, stress, magnitude, failure

1. A … is the force within a metal which resists deformation due to an externally applied load.

2. Besides static loads many parts of machines are subjected to … loads.

3. As a result of the prolonged action of cyclic stresses, the metal gradually converts from the plastic to the brittle state, i.e. experiences ….

4. Deformations or strains in a metal can cause its ….

5. Alternating forces can change either in direction or in … or both.

6. Metals are … to various tests to obtain information on their mechanical properties.

7. Strength is the resistance of a metal to forces that tend to … it or cause deformation.

8. Elasticity is the ability of a metal to return to its … size and shape after the removal of the … forces.

9. If the forces acting on a metal … the elastic limit of this metal, it will fracture.

10. Under … a metal usually stretches.

11. Materials at high temperatures usually suffer from ….

12. When a metal is twisted, it is under the action of the … force.

1. Agree or disagree with the following statements. Prove your reason. Use the expression: It goes without saying that …

1. Technical progress depends on the quality of metals.

2. Metals are subjected to one type of loads.

3. It is important to know how metals respond to external forces.

4. Alternating loads change only in magnitude.

5. Deformation shows fatigue of a metal.

6. Compression increases volume.

7. The material ruptures if the external force exceeds its elastic limit.

8. Tensile and compressive forces cannot work simultaneously.

9. Under tension a material usually stretches.

10. Fatigue is the growth of cracks under stress.

8. Translate the following sentences paying attention to the Participle. Find the examples of the Parrticiple in the text:

1. When tin was added into molten copper, bronze was born.

2. Using only stone hammer and stone anvil people could work gold.

3. Being malleable and ductile gold can be easily worked.

4. When hammered copper becomes harder and stronger.

5. Ores are minerals bearing rock and metal.

6. Copper was one of the first metals known to people.

7. Metals do not melt until heated to a definite temperature.

8. Unless heated this metal cannot be liberated from its ore.

9. Nickel added to steel increases its strength.

10. We can harden steel heating it to a certain temperature and then quickly cooling in water.

11. Special steels must be used for parts requiring great wear resistance.

12. While determining the plasticity of metals a special rupture machine is used.

1. Translate the text in writing. Use a dictionary. Find answers to the questions:

1. What is strength?

2. What is hardness?

3. What is weldability?

4. What is malleability?

The mechanical properties of a metal indicate its strength, hardness, elasticity, and impact strength, or toughness. Strength is the resistance of a metal to forces that tend to rupture it or cause residual deformations.

The specific strength is the ratio of the ultimate strength to the density of a metal. The ultimate strength of steel is greater than that of aluminum, but the specific strength is lower. Hardness is the ability of a metal to resist surface deformation under the action of a harder substance. Elasticity is the ability of a metal to resume its original size and shape after removal of external forces. Impact strength (toughness) is the resistance of a metal to impacts. In addition to these properties we can mention such important properties as fatigue (endurance), creep, and ductility. Metals are subjected to various tests to get information on their mechanical properties.

In addition to mechanical properties of metals it is important to know their technological properties, such as weldability, malleability and workability. Weldability is the ability of metals to form strong permanent joints between metal pieces by heating the surfaces to be welded to the plastic or liquid state. Weldability is a very important property since it determines the productivity, economic efficiency, and the strength of the welded joints. Malleability is the property of a metal to be worked under pressure in forging, rolling, and stamping. This property enables a metal to acquire the desired shape in the cold or hot state. Workability is the ability of a metal to lend itself to any kind of metalworking. For example, machinability indicates the ease of machining (cutting) a metal as compared to a basic standard.

Unit 8

1. Memorize the following words and expressions:

solidify particle deposition pattern grain coarse-grained fine-grained fibrous space lattice body-centered face-centered random extend direction nucleus(nuclei)   proceed by means of convert consist (of)

затвердевать частица отложение модель зерно крупнозернистый мелкозернистый волокнистый пространство решетка объемно-центрированная гранецентрированная беспорядочный простираться направление ядро (ядра), центр кристаллизации продолжать(ся) посредством превращать состоять (из)

затвердіти частинка відкладення модель зерно крупнозернистий дрібнозернистий волокнистий простір решітка об’ємноцентрована гранецентрована безладний простягатися напрямок ядро (ядра), центр кристалізації продовжувати(ся), тривати за допомогою, через перетворювати складатися

1. Practise the reading of the following words:

Crystal, crystallize, crystalline, crystallization, solidify, lattice, uninterrupted, cube, cubic, numerous, collision, similarly, imperfect, fractured, surface, coarse, fibrous, geometrical, pattern, x-rays, entirely, homogeneous, nuclei, gradual.