Read text B again to decide if the statements are “True” or “False”. Correct the false ones using facts from the text.

1) Tempering is seldom performed after hardening.

2) Very hard tools are often tempered at high temperatures.

3) The reduction in hardness is accompanied by an increase in ductility.

4) Precise control of time and temperature during the tempering process isn’t crucial to achieve the desired balance of physical properties.

5) Many steels with high concentrations of alloying elements behave like precipitation hardening alloys.

6) Tempering is also performed on normalized steels and cast irons, to increase ductility, machinability, and impact strength.

Ask 5 questions to text B in writing. Let your classmates answer them.

Give a summary of text B (in 8-9 sentences).

Read the text “Tempering colors”. Translate it in writing. Use a dictionary if necessary.

Tempering colors

Pieces of through-tempered steel flatbar. The first one, on the left, is normalized steel. The second is quenched, untempered martensite. The remaining pieces have been tempered in an oven to their corresponding temperature, for an hour each. "Tempering standards" like these are sometimes used by blacksmiths for comparison, ensuring that the work is tempered to the proper color.

If steel has been freshly ground, sanded, or polished, it will form an oxide layer on its surface when heated. As the temperature of the steel is increased, the thickness of the iron oxide also increase.

 

Although iron oxide is not normally transparent, such thin layers do allow light to pass through, reflecting off both the upper and lower surfaces of the layer. This causes a phenomenon called thin film layer, which produces colors on the surface. As the thickness of this layer increases with temperature, it causes the colors to change from a very light yellow, to brown, then purple, then blue. These colors appear at very precise temperatures, and provide the blacksmith with a very accurate gauge for measuring the temperature. The various colors, their corresponding temperatures, and some of their uses are:

· Faint-yellow – 176 °C (349 °F) – engravers, razors, scrapers

· Light-straw – 205 °C (401 °F) – rock drills, metal-cutting saws

· Dark-straw – 226 °C (439 °F) – scribers, planer blades

· Brown – 260 °C (500 °F) – taps, dies, drill bits, hammers, cold chisels

· Purple – 282 °C (540 °F) – surgical tools, punches, stone carving tools

· Dark blue – 310 °C (590 °F) – screwdrivers, wrenches

· Light blue – 337 °C (639 °F) – springs, wood-cutting saws

· Grey-blue – 371 °C (700 °F) and higher – structural steel

Beyond the grey-blue color, the iron oxide loses its transparency, and the temperature can no longer be judged in this way. The layer will also increase in thickness as time passes, which is another reason overheating and immediate cooling is used. Steel in a tempering oven, held at 205 °C (401 °F) for a long time, will begin to turn brown, purple or blue, even though the temperature did not exceed that needed to produce a light-straw color. Oxidizing or carburizing heat sources may also affect the final result. The iron oxide layer, unlike rust, also protects the steel from corrosion through passivation.

 

10. a) What do you know about the Bessemer process of steel production? Prepare a presentation and tell your classmates about:

1) Henry Bessemer’s biography.

2) Henry Bessemer’s first inventions.

3) The Bessemer process of steel production.

b) Use the following cliches:

1. First …

2. Then … / Secondly …

3. After that …

4. Later …

5. Finally …

Part III

Learn the words.

annealing	отжиг
alter	изменять, превращать
bond	1) связь, соединение, сцепление 2) крепитель; связующее вещество
coarsen	укрупнять
decarburation	обезуглероживание
dislocation	дислокация
forming	1) штамповка, гибка листового металла 2) формовка
forming gas	газ для (взрывной) формовки
lattice	кристаллическая решетка
quenching	1) закалка, резкое охлаждение 2) гашение, тушение (напр. кокса)
recrystallization temperature	температура рекристаллизации
shaping	формование, формовка
stamping	листовая штамповка; чеканка
stress relief	снятие напряжения
workable	обрабатываемый; годный для обработки; деформирующийся