4. Complete the sentences.

1. An understanding of the compositional and structural factors controlling hardening of iron or steel was not archived …

2. Heat treatment is the process of …

3. Steels can be heat treated to …

4. Structural components subjected to high operating stress need …

5. Most steels weld better in …

6. Stress relieving is used where …

7. … is frequently diffused into the surface of soft steels for …

8. … is a heat treatment that reduces the brittleness of a steel.

5. Match the following English words and word-combinations with their Ukrainian equivalents.

1. heat treatment a. гартування

2. to subject to b. охолодження

3. structural factors c. розсіювання

4. to weld d. відпускання (сталі)

5. relieving e. піддавати (чомусь)

6. alloying elements f. леговані елементи

7. cooling g. полегшення, зниження

8. hardening h. зварювати

9. tempering i. теплова обробка

10. diffusion j. структурні фактори

6. True or false statements.

1. The main reasons for heat treating are hardening, softening a hardened structure, stress relieving, diffusion of alloying elements, tempering.

2. Steels can not be heat treated to high hardness and strength level.

3. Cutting and forming devices need a hardened structure.

4. Stress relieving removes internal strains with lowering strength.

5. The criteria for hardening a steel is that it has sufficient boron content.

6. Carbon is frequently diffused into the surface of hard steels for surface softening.

7. Tempering is a heat treatment that increases the brittleness of a steel.

II. Retell the text “Heat Treatment of Steels”

III. Rendering

1. Read the text and translate it into Ukrainian using a dictionary. Heat-Treatment Operations

Heat-treatment. An operation, or combination of operations, involving the heating

and cooling of a metal or an alloy in the solid state, for the purpose of obtaining certain desirable conditions or properties.

Quenching. Rapid cooling by immersion in liquids or gases or by contact with metal.

Hardening. Heating and quenching certain iron-base alloys from a temperature either within or above the critical range for the purpose of producing a hardness superior to that obtained when the alloy is not quenched. Usually restricted to the formation of martensite.

Annealing is a heating and cooling operation implying usually a relatively slow cooling. The purpose of such a heat-treatment may be (1) to remove stresses; (2) to induce softness; (3) to alter ductility, toughness, electrical, magnetic, or other physical properties; (4) to refine the crystalline structure; (5) to remove gases; or (6) to produce a definite microstructure. The temperature of the operation and the rate of cooling depend upon the material being heat-treated and the purpose of the treatment. Certain specific heat-treatments coming under the comprehensive term annealing are as follows:

Fuel Annealing. Heating iron-base alloys the critical temperature range, holding above that range for a proper period of time, followed by slow cooling to below that range. The annealing temperature is generally about 100 F above the upper limit of the critical temperature range, and the time of holding is usually not less than 1 hr for each inch of section of the heaviest objects being treated. The objects being treated are ordinarily allowed to cool slowly in the furnace. They may, however, be removed from the furnace and cooled in some medium that will prolong the time of cooling as compared with unrestricted cooling in the air.

Process Annealing. Heating iron-base alloys to a temperature below or close to the lower limit of the critical temperature range followed by cooling as desired. This heat treatment is commonly applied in the sheet and wire industries, and the temperatures generally used are from 1020 to 1200 F.

Normalizing. Heating iron-base alloys to approximately 100 F above the critical temperature range followed by cooling to below that range in still air at ordinary temperature.

Patenting. Heating iron-base alloys above the critical temperature range followed by cooling below that range in air, in molten lead, or a molten mixture of nitrates or nitrites maintained at a temperature usually between 800 to 1050 F, depending on the carbon content of the steel and the properties required of the finished product. This treatment is applied in the wire industry to medium – or high-carbon steel as a treatment to precede further wire drawing.

2. Make up a plan in the form of questions.

3. Give the summary of the text according to your plan in a written form.

IV. Comprehensive skills

1. Read and remember.

adjacent [ə’dʒəis(ə)nt] adj суміжний

agitation [‚ædʒi’tei∫(ə)n] nзбовтування, перемішування

distortion [dis’tƆ: ∫(ə)n] n викривлення

fume [fju:m] n дим, кіпоть

hazard [’hæzəd] n ризик, небезпека

likelihood [’laiklihud] n імовірність

medium [’mi:djəm] n середовище

plunge [plʌndʒ] v занурювати

rinse off v змивати

spill n паперовий жмут, лучина

transition [træn’siʒ(ə)n] n перехід

vaporize [’veipəraiz] v випарювати

2. Listen to the text “Quenching” and try to understand it.

3. True or false statements.

1. Quenching can be done by plunging the hot steel in water.

2. As the water contacts and boils, a great amount of heat is not removed from the steel.

3. Water is a bad rapid quenching medium.

4. Oil doesn’t have a very high boiling point.

5. Water is corrosive with steel.

4. Listen to the text once again and answer the following questions.

1. What is quenching?

2. Why can the rapid cooling sometimes cause distortion or cracking?

3. Why must salt water be rinsed off immediately?

4. When is oil used?

5. What does oil quenching result in?

V. Communicative skills

Topic for discussion:

1. The main heat-treatment operations;

2. The reasons for heat treating;

3. The thermal cycles for annealing, normalizing, hardening and tempering.

Unit 6

Topic: Non-ferrous metals and their alloys