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IV. Прочтите, перепишите и переведите.
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METHODS OF STEEL HEAT TREATMENT
Metals are materials most widely used in industries because of their properties. It should be mentioned metals vary greatly in their properties that depend on the size, shape, orientation and composition of the metal grains. Heat treatment such as quenching, tempering and annealing control the nature of the grains and their size in metal.
Quenching is a heat treatment when metal at a high temperature is rapidly cooled by immersion in water or oil. Quenching makes steel harder and more brittle, with small grains structure.
Tempering is a heat treatment applied to steel and certain alloys. Hardened steel after quenching from a high temperature is too hard and brittle for many applications. Tempering, that is re-heating to an intermediate temperature and cooling slowly, reduces this hardness and brittleness. Tempering temperatures depend on the composition of the steel but are frequently between 100 and 650 °C. Higher temperatures usually give a softer, tougher product. The colour of the oxide film produced on the surface of the heated metal often serves as the indicator of its temperature.
Annealing is a heat treatment in which a material at high temperature is cooled slowly. After cooling the metal again becomes malleable and ductile (capable of being bent many times without cracking).
All these methods of steel heat treatment are used to obtain steels with certain mechanical properties for certain needs.
quenching - закалка
tempering - отпуск после закалки
annealing - отжиг, отпуск
V. Ответьте на вопрос: What do the properties of metals depend on?
КОНТРОЛЬНОЕ ЗАДАНИЕ №2 (Вариант 4) (“АВ”, “ИМ”)
I. Перепишите следующие предложения; подчеркните в каждом из них глагол-сказуемое и определите его видо-временную форму и залог. Переведите предложения на русский язык. В разделе (б) обратите внимание на перевод пассивных конструкций.
а) 1.. Thousands of researchers and scientists have taken part in the conference.
2. They are still looking for the suitable material for this purpose.
б) 1. Synthetic rubber products were developed between 1914 and the 1930s.
2. Many compounds can be decomposed when they are acted upon by different forms of energy.
II. Перепишите следующие предложения; подчеркните Particle I и Particle II и установите функцию каждого из них, т.е. укажите, является ли оно определением, обстоятельством или частью глагола-сказуемого. Переведите предложения на русский язык.
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1. Natural rubber is a thermoplastic material that becomes soft when heated and hard when cooled.
2. Matter composed of any chemical combination of elements is called a compound.
3. The machine-tool having some suitable for them characteristics required special lubricant.
4. To achieve a device with desired service life the engineers spent 2 years.
III. Перепишите следующие предложения; подчеркните в каждом из них модальный глагол или его эквивалент. Переведите предложения на русский язык.
1. These metal parts had to be subjected to X-ray examination.
2. You may use this device to analyze its exact composition.
3. These new materials should to withstand much higher temperatures than the metals.
4. Ethylene gas can be obtained by cracking petroleum.
IV. Прочтите, перепишите и переведите.
METALS
Metals are materials most widely used in industry because of their properties. 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's why metals are malleable and ductile. 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 a pure metal. This is called alloying and it changes the grain structure and properties of metals.
All metals can be formed by different metalworking processes, but some require hot-working. Both metal fatigue (усталость металла) and creep (ползучесть) are taken into account by engineers when designing, for example, airplanes, gas-turbines, and pressure vessels for high-temperature chemical processes. The ways of working a metal depend on its properties.
dense - плотный
grains - зерна
coarse- грубый, крупный
alloying - легирование
quenching - закалка
tempering - отпуск после закалки
annealing - отжиг, отпуск
V. Ответьте на вопрос: What changes the size of grains in metals?
КОНТРОЛЬНОЕ ЗАДАНИЕ №2 (Вариант 5) (“АВ”, “ИМ”)
I. Перепишите следующие предложения; подчеркните в каждом из них глагол-сказуемое и определите его видо-временную форму и залог. Переведите предложения на русский язык. В разделе (б) обратите внимание на перевод пассивных конструкций.
а) 1. The engineers have developed several types of metal treatment to harden it.
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2. The problem of achieving low-cost material with the longest service life is still occupying the minds of many scientists.
б) 1. As a rule one great discovery is generally followed by numerous others.
2. The material properties are determined by many factors.
II. Перепишите следующие предложения; подчеркните Particle I и Particle II и установите функцию каждого из них, т.е. укажите, является ли оно определением, обстоятельством или частью глагола-сказуемого. Переведите предложения на русский язык.
1. The smallest particle having all the characteristics of an element is called a compound.
2. Matter consists of one or more basic elements occurring in nature.
3. When heated to a certain temperature this alloy increases in volume.
4. Adding of some amount of carbon made it possible to obtain steel with desired properties.
III. Перепишите следующие предложения; подчеркните в каждом из них модальный глагол или его эквивалент. Переведите предложения на русский язык.
1. New types of plastics had to be obtained for this purpose.
2. To measure the clearance between these two parts you can use this device.
3. This material should find its applications in the industry.
4. That part may withstand much lower temperatures than this one.
IV. Прочтите, перепишите и переведите.
METALWORKING PROCESSES
Metals are important in industry because they can be easily deformed into useful shapes. A lot of metalworking processes have been developed for certain applications. They can be divided into five broad groups: rolling, extrusion, drawing, forging, sheet-metal forming.
Extrusion is pushing the billet to flow through the orifice of a die. Products may have either a simple or a complex cross section. Aluminium window frames are the examples of complex extrusion.
Tubes or other hollow parts can be also extruded. The initial piece is a thick-walled tube and the extruded part is shaped between a die on the outside of the tube and a mandrel held on the inside.
In impact extrusion (also called back-extrusion) the workpiece is placed in the bottom of a hole and a loosely fitting ram is pushed against it. The ram forces the metal to flow back around it with the gap between the ram and the die determining the wall thickness. The example of the process is the manufacturing of aluminium beer cans.
Drawing consists of pulling metal through a die. One type is wire drawing. The diameter reduction that can be achieved in one die is limited but several dies in series can be used to get the desired reduction.
Forging is the shaping of a piece of metal by pushing with open or closed die.
Sheet metal forming is widely used when parts of certain shape and size are needed.
rolling - прокатка
extrusion -выдавливание, экструзия
drawing -волочение
forging - ковка
sheet-metal forming - штамповка листового металла
back-extrusion - штамповка выдавливанием
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