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II. Match the term with its definition.

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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

 

III. 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

 

IV. 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 strengthof amaterial 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 forceand 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.

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

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

   Toughness. - Toughnesshas 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. - Malleabilityis the property of a metal which permits permanent deformation by compression without rup­ture.

Brittleness. - Brittlenessimplies 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 corrosionfatigue 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.

 

NOTES AND COMMENTARY

depends upon -зависит of which the metals are constructed – из которых состоит металл tenacity of adherence –прочность сцепления force within a body– сила, действующая в теле due to – зд. в результате a unit force –единичная сила a unit stress- напряжение is in proportion to the load – пропорционален нагрузке subjected to –подвергнутый original dimentions –первоначальные размеры too great –слишком большой upon removal –после устранения about one another –один вокруг другого yield point– предел текучести strain curve –кривая деформации levels off– понижается (спадает) mild steels –малоуглеродистые стали ultimate tensile strength –предел прочности при растяжении, сопротивление разрыву ultimate strength –предел прочности to be permanently deformed in ten­sion –постоянно деформироваться в растяжении is indicated by the amount of slip which may occur within the cry­stals –определяется величиной сдвига, который может произойти в кристаллах breaking without warning –внезапный разрыв, разрыв без предупреждения under repeated or alternating stres­ses –при повторяющихся или чередующихся напряжениях fatigue failure –излом усталости number of physical and mechani­cal properties –ряд физических и механических свойств  

 

EXERCISES

I. Make words out of these letters and translate them into Russian.

1) tacesinser

2) ibsivel

3) ranetexl

4) canytiet

5) thgenrst

6) rooornisc

7) recendanu

8) larufei

9) guhsensot

10) lilelbaityma

 

II. Name the property according to its definition.

1) - the property of regaining the original dimen­sions upon removal of the external load.

2) - the property of breaking without warning.

3) - a combination of a number of physical and mechanical properties.

4) - a point on the stress - strain curve at which the stress levels off or actually decreases while strain continues.

5) - the capacity of a metal to be per­manently deformed in tension without breaking.

6) - the property of resistance to external loads or stresses without incurring stru­ctural damage.

7) - the property of a metal which permits permanent deformation by compression without rup­ture.

 

III. Make up definitions out of these words and name the property.

1) separation, another, atoms, a resistance, or, or, of, to, rotation, one, about compression.

2) which, permanent, a metal, the property, of, deformation, without, by, compression, rupture, permits.

3) mechanical, a number, a combination, properties, of, of, and, physical.

4) before, absorbing, the property, fracture, considerable, of, energy.

5) due to, within, load, deformation, a body, which, an, applied, the force, externally, resists.

 

IV. Finish the sentences according to the text.

1) Ductility is the capacity of a metal to be permanently deformed …

2) Elasticity is demonstrated as …

3) When an external force acts upon an elastic material …

4) Elastically stressed materials return to their original dimensions when …

5) The strength of metals and alloys depends upon two factors: …

 

Unit 4. Foundry equipment.

 

 

1-12 melting plant– плавильная установка 1 cupola furnace (cupola), a melting furnace –вагранка, плавильная печь 2 blast main (blast inlet, blast pipe) -воздухопровод 3 tapping spout –выпускной желоб 4 spyhole –смотровое отверстие 5 tilting-type [hot-metal] receiver –приемник расплавленного металла 6 mobile drum-type ladle –передаточный ковш барабанного типа 7 melter- плавильщик 8 founder (caster)-заливщик 9 tap bar (tapping bar) –лом для пробивания летки 10 bott stick (Am. hot stick) –глиняная пробка на стержне летки 11 molten iron – расплавленный чугун 12 slag spout –выпускной желоб для шлака 13 casting team –бригада заливщиков 14 hand shank –ручной литейный ковш 15 double handle (crutch) –хомут с ручками 16 carrying bar –хомут для переноски ковша 17 skimmer rod –лопата для перекачивания шлака 18 closed moulding (Am. molding) box –закрытая опока 19 upper frame (cope) –верхняя опока 20 lower frame (drag) –нижняя опока 21 runner (runner gate, down-gate) –литейная часть со стояком 22 iser (riser gate) -выпор 23 hand ladle – ручной литейный ковш 24-29 continuous casting –непрерывная разливка 24 sinking pouring floor –опускающийся пол разливочного пролета 25 solidifying pig –затвердевший чугун 26 solid stage –твердое состояние 27 liquid stage –жидкое состояние 28 water-cooling system –система водяного охлаждения 29 mould (Am. mold) wall –стенка литейной формы 30-37 moulding (Am. molding) department (moulding shop) –формовочное отделение 30 moulder (Am. molder) –формовщик 31 pneumatic rammer –пневматическая тромбовка 32 hand rammer –ручная тромбовка 33 open moulding (Am. molding) box –открытая формовочная опока 34 рattern -модель 35 moulding (Am. molding) sand –формовочная смесь 36 сore –литейный стержень 37 core print –стержневой знак 38-45 cleaning shop (fettling shop) –очистное отделение 38 steel grit or sand delivery pipe –распределительная труба для песка 39 rotary-table shot7blasting machine –дробеструйная машина с вращающимся столом 40 grit guard –ограждение от дроби 41 revolving table –вращающийся стол 42 casting -отливка 43 fettler -обрубщик 44 pneumatic grinder –пневматический шлифовальный станок 45 pneumatic chisel –пневматическое зубило

FOUNDARY

METAL CASTING

One of the basic processes of the metal-working industry is the production of metal castings. Numerous methods have been developed through the ages for producing metal castings, but the oldest method is that of making sand castings in the foundry. Primarily, work consists of melting metal in a furnace and pouring it into suitable sand molds, where it solidifies and assumes the shape of the mold. However, the operation of making sand castings is not as simple as it seems

Metal-castings methods may be classified into three groups depending upon the type of mold used and the manner in which the molten metal is introduced into the mold.

The mold may be made from heat-resisting material, such as sand, some suitable ceramic material, or plaster. The kind of material chosen to make the mold is, of course, determined primarily by the melting temperature of the cast metal. Molten metals may be poured into the mold by gravity or, on the other hand, pressure may be applied to force the liquid metal into the mold. The latter method is known as die casting. Die-cast­ing pressure may be furnished by air, hydraulic means, mecha­nical means, or centrifugally.

Among the mold materials, sand is used more than all others, since it can be packed to any required shape with small effort.

This method of production is relatively simple, inexpensive, and is not limited to any particular type of metal or to certain sizes and shapes of castings. Of course, sand molds are used only once, and each casting requires a new mold.

Wider use of the permanent type of mold made from steel, iron or any other suitable metal, depending upon the melting temperature of the cast metal, is therefore greatly desired.

Bronze molds are employed at times for casting metals and alloys of very low melting temperature such as zinc-base and lead-base alloys.

Modern casting techniques also permit that steel molds, coated inside with refractory material, also be successfully used for production of iron and steel castings.

The metal molds are usually made in two parts which are either clamped together or closed by a screw or other suitable device. The molten metal may be introduced into the mold either by gravity or pressure.

The inner surfaces of the metal mold are in most cases finished smooth. They can be re-used. These qualities make them superior to sand castings.

NOTES AND COMMENTARY

through the ages –в течение веков the oldest method is that of sand castings –древнейшим методом является метод литья в земляные формы assumes the shape of the mold –принимает форму изложницы depending upon the type of mold used –в зависимости от типа используемой формы introduced into –выливается в by gravity –силой тяжести on the other hand –с другой стороны die casting –литье под давлением may be furnished –может осуществляться   it can be packed to any required shape –ему можно придать любую нужную форму sand molds are used only once –воспользоваться земляными изложницами можно только один раз at times –иногда coated inside –покрытые внутри refrectory material –огнеупорный материал made in two parts –изготовляется из двух частей in most cases finished smooth –в большинстве случаев изготовляется гладкой

 

EXERCISES




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