2. Match the term with its definition.

1) porosity 2) composition 3) melting point 4) boiling point 5) electrical conductivity 6) density

a) the temperature at which a metal melts b) the electrical conducting power of a unit of cross sectional area c) the quality of containing pores is lack of denseness d) the temperature at which the metal boils under normal atmospheric pressure e) the manner of arrangement of metal atoms as to geometric form in solid crystals f) weight per unit of volume

3. Find in the text sentences containing the following words and translate them into Russian.

1. solid crystals

2. composition

3. surface

4. cooling

5. electrical resistance

6. lightweight metals

7. to leak

8. resistivity

9. the solidified mass

10. denseness

4. Find 13 words on the topic in the crossword-puzzle and give their Russian equivalents.

C	O	N	D	I	T	I	O	N	F
I	F	I	O	I	T	A	M	R	O
E	D	D	N	S	C	O	N	D	U
F	R	I	L	O	G	V	I	T	C
I	E	E	Z	I	N	I	T	Y	A
M	P	U	R	I	T	I	L	I	B
M	U	L	O	V	Y	T	Y	P	R
E	L	L	A	G	I	E	W	S	E
A	O	Y	T	H	T	S	B	U	S
R	T	E	C	N	A	E	R	U	S

Unit 3. Mechanical properties of metals and alloys

Strength. - The strength of a material is the property of resistance to external loads or stresses without incurring stru­ctural damage.

The strength of metals and alloys depends upon two factors, namely, the strength of the crystals of which the metals are constructed and the tenacity of adherence between these cry­stals.

Stress and Strain. - A stress is the force within a body which resists deformation due to an externally applied load. If this load acts upon a surface of unit area, it is called a unit force and the stress resisting it a unit stress.

When an external force acts upon an elastic material, the material is deformed and the deformation is in proportion to the load. This distortion or deformation is strain.

Elasticity. - Any material subjected to an external load is distorted or strained. Elastically stressed materials return to their original dimensions when the load is released if the load is not too great. The property of regaining the original dimen­sions upon removal of the external load is known as elasti­city.

The Nature of Elasticity. - The elasticity of a metallic sub­stance is a resistance of its atoms to separation or compres­sion or rotation about one another, and thus is a fundamental property of the material. So elasticity is demonstrated as a function of atomic forces.

Yield Point. - This is a point on the stress - strain curve at which the stress levels off or actually decreases while strain continues. The term is strictly applicable only to mild steels.

Ultimate Strength. - The greatest load that the specimen has supported divided by the original cross-sectional area is called the ultimate tensile strength or the ultimate strength of the piece.

Ductility. - Ductility is the capacity of a metal to be per­manently deformed in tension without breaking.

Toughness. - Toughness has been defined as the property of absorbing considerable energy before fracture. The tough­ness of a metal is indicated by the amount of slip which may occur within the crystals without resulting in rupture of the metal.

Malleability. - Malleability is the property of a metal which permits permanent deformation by compression without rup­ture.

Brittleness. - Brittleness implies sudden failure. It is the property of breaking without warning, i.e., without visible permanent deformation.

Failure of metals and alloys under repeated or alternating stresses, too small to produce even a permanent deformation when applied statically, is called fatigue failure.

Corrosion Fatigue. - Failure by corrosion fatigue is a fati­gue failure in which corrosion has lowered the endurance limit by the formation of pits that act as centers for the development of fatigue cracks.

Hardness. - The quality of hardness is a combination of a number of physical and mechanical properties.