TOPIC 8. FORMING, WORKING AND HEAT-TREATING METAL

Text 1

1.Обратите внимание на перевод следующих слов и словосочетаний:

сasting - литье, отливка;

die - штамп (инструмент, металлическая форма для серийного изготовления изделий штамповкой, тиснением, давлением или чеканкой);

sintering - обжиг;

molten metal - жидкий металл, расплавленный металл;

solid mass -    твёрдая масса;

extrusion - выдавливание (на прессе);

shaping tool - фасонный инструмент, строгальный резец, фасонный резец.

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CASTING, SINTERING AND EXTRUDING METAL

Metal can be formed into shapes using heat and pressure. Casting involves heating metal until it becomes molten (liquid) and pouring it, or forcing it under pressure, into a mould called a die. Instead of being cast, metal components can be formed by sintering. This is done by using metal powder instead of molten metal. The powder is placed in a die and compressed into a solid mass. It is then heated (though not melted) until it becomes sintered - that is, the powder particles join together structurally, due to the heat.

Metal can also be shaped by extruding it into long lengths. Extrusion involves heating metal until it is molten, then forcing it at high pressure through a shaping tool- also called a die to form bars or tubes, for example. At the same time, the metal cools and becomes solid.

Text 2

1.Обратите внимание на перевод следующих слов и словосочетаний:

forge - кузница, горн;

hammering - ковка;

forging - ковка;

automated machines - станок-автомат;

drop forging - объёмная штамповка на падающем молоте;

hot rolled metal - горячекатаный металл;

cold rolled metal - холоднокатаный металл;

shot-peened - обдутый дробью.

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WORKING METAL

 Traditionally, many metal tools were made by heating iron bars in a fire, called a forge, until they were red hot or (hotter still) white hot. The metal was then worked- in other words, shaped by hammering it. Working metal using compression (for example, hammering) is also called forging. The same basic technique is still in use today, especially with steel. However, large, automated machines are now used. Metal is often worked (or forged) when hot (hot forged), but may also be worked when it is cold (cold forged).

 A common forging technique is drop forging, where a heavy hammer is dropped onto a piece of metal. A die fixed to the hammer compresses the metal into the required shape. Rollers can also be used to apply compression, with or without heat, to produce hot rolled or cold rolled metal.

 Forging also increases the hardness of metal. This is called work hardening. Metal becomes work hardened because its structure is changed by compression. The same result can be achieved without hammering or rolling - and therefore without changing the component's shape – by shot-peening. This involves firing small metal balls (metal shot) at the surface of components (when cold), at high speed. After components have been shot-peened, their surface is significantly harder.

Text 3

1.Обратите внимание на перевод следующих слов и словосочетаний:

heat treating - термическая обработка (металла);

quenching -     закаливание, охлаждение;

annealing - прокалка;

tempering -     закалка с последующим отпуском;

precipitation hardening - дисперсионное твердение;

case hardening - поверхностное упрочнение.

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HEAT TREATING METAL

The properties of a metal can be changed by heat treating it- that is, heating and cooling the metal. The table below, from the technical information section of a steel supplier's website, summarizes the main types of heat treatment.

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