3. Find the answers to the questions.

1. Did Copper become one of the first engineering metals?

2. How can copper occur in nature? And how can mass copper be obtained?

3. What is the cost of copper today? Do you know the use of copper at householding?

4. Are copper and copper alloys indispensable engineering materials?

5. What is the difference between a brass and a bronze?

6. What other copper alloys do you know? And what are its principal alloying elements?

7. What do you think, is aluminum the second wide acceptable engineering material?

8. How does aluminum occur in nature?

9. What is the cost of aluminum?

10. What are the properties of aluminum that set it apart from other metals?

11. Why is aluminum considered to be the most widely used metallic material?

12. What are the most important alloying elements in aluminum alloy systems?

4. Complete the sentences.

1. Metals are generally tested according to …

2. Copper became one of the first engineering metals because it can occur in nature …

3. … are indispensable engineering materials.

4. A brass is a copper alloy containing …

5. The alloys of copper and nickel are now called …

6. … is the most abundant metal in nature

7. May rocks and minerals contain …

8. There are several properties that set aluminum …

9. … is lighter than all other engineering metals except magnesium and beryllium.

10. The most important alloying elements in aluminum alloy systems are …

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

1. indispensable a. той, що не містить заліза

2. alloy b. свинцева латунь

3. low-grade ore c. магній

4. non-ferrous d. застосування

5. magnesium e. необхідний, обов’язковий

6. Libra f. руда низької якості

7. yield strength g. сплав

8. leaded brass h. марганець

9. manganese i. фунт

10. application j. міцність на текучість

6. True or false statements.

1. There are five non-ferrous metals of primary commercial importance: copper, zinc, lead, tin and aluminum.

2. Copper can occur in nature in the metallic form as well as an ore.

3. Copper and copper alloys are indispensable engineering materials.

4. Copper and copper alloys don’t have electrical and thermal conductivity.

5. The term bronze means a copper alloy with zinc as the major alloying element.

6. Aluminum was first produced in 1925.

7. Aluminum occurs in nature in the metallic form.

8. Aluminum is heavier that all other engineering metals.

9. For application involving atmospheric corrosion resistance aluminum is the most widely used metallic material.

II. Retell the text “Non-ferrous metals and their alloys. Aluminum”.

III. Rendering

1. Read the text and translate it into Ukrainian using a dictionary. Other engineering metals and their alloys

Nickel. Nickel as an element was discovered in 1750 but had limited uses until this century, when it became an essential alloying element in stainless steels and high alloys. The ore is usually deep mined, and the normal flotation and concentration processes are used to arrive at the starting material for making metallic nickel.

Pure nickel is similar in many properties to an annealed low-carbon steel. It looks like steel; it is ferromagnetic, but not as much as steel.

The most important nickel alloy systems are the following:

1. Pure nickel alloys.

2. Nickel-copper alloys.

3. Nickel-chromium alloys.

4. Nickel-chromium-iron alloys.

The largest use of nickel is as an alloying element in stainless steel, steel, coppers, and other metals. The use of nickel-base alloys is really limited to special applications with corrosion resistance being a primary area of application. It is intended to let the designer know that there are nickel-base alloys available for corrosion problems where stainless steels and other alloys fail. Similarly, there are nickel-base alloys that have special properties useful in sophisticated magnetic and electrical devices.

Zinc. Zinc and its alloys are not often thought of as suitable materials for engineering design, but the largest use of zinc is for protective coatings on steels and other metals that are used in machine design. The second largest use for zinc is in die castings, and these also are used in machines.

Zinc was used for centuries before it was officially “discovered”. Zinc ores were combined with copper ores and refined to produce the alloy that we know today as brass. As a pure metal, zinc was identified in about 1750. Zinc occurs in nature primarily in sulfide ores that contain a few percent of zinc.

Titanium. Titanium is probably the newest engineering metal. As an element it was discovered in 1791, but it was not produced in metallic form until 1910. It remained a laboratory curiosity until commercial processes were developed for its manufacture in the 1940s. Titanium is abundant in nature; about 1% of the earth’s crust is titanium. As a pure metal, titanium has a melting point higher than steel, 3040˚F(1671˚C).

The physical properties of prime importance are its density and modulus. It weighs only about one half as much as steel. Its mechanical properties can be better than many alloy steels, and thus it has a very high specific strength. The same thing is true about stiffness. It has a much higher modulus than the light metals, magnesium and aluminum.

Production processes have been improved significantly, and metal costs are now down to about $4/lb; commercial use of this metal is becoming very common.

Titanium and its alloys are widely used in aircraft for their strength and fatigue resistance, and on industrial machines they can be used wherever mass effects must be reduced and high strength is needed: high-speed rolls, quick-acting latches, clutches, high-temperature springs, torsion bars, and the like. Titanium is no longer an exotic metal. It can be used by the average constructer.

Refractory metals. The refractory metals are used for even more specialized applications. No matter how infrequently a designer uses these metals, they should be part of his material repertoire. They can solve problems where the traditional metals may fail. Refractory metals are metals with very high melting points. Generally, this means higher than the melting point of steels (~2800˚F; 1540˚C). Ten or so metals may fulfill this requirement. Molybdenum, with a melting point of 4730˚F (2422˚C), can have usable strength up to temperatures as high as 3000˚F (1650˚C) in reducing atmospheres. An example where molybdenum has solved severe service problems is in aluminum die casting cavities. In some carburetor castings, aluminum entered the cavity at a core pin for a bolt hole. The hot-work tool steel core pin failed by thermal fatigue after a few thousand parts. The problem was solved by using TZM, a molybdenum, 0,1% zirconium, 0,5% tungsten alloy.

Tantalum can be called the most-corrosion-resistant metal. It is resistant many oxidizing and reducing acids up to their boiling points. It is used in a wide variety of applications where stainless steels, titanium, the super alloys of nickel, and molybdenum do not work. Its application must be judicious, however, because of its price of about $100/lb.

Tungsten, with a melting point of 6170˚F (3420˚C), is used in welding equipment for no consumable electrodes, in electrical equipment as an electron emitter, and of course it is the hot wire in incandescent lamps. In machines, tungsten-base alloys can be useful for quite another reason than their high melting point. Tungsten has a specific gravity of 19.4, almost twice that of lead (specific gravity 11,3). In a machine there is a need for a component with high inertia, for example, a flywheel. If there are space limitations and it is not possible to make a massive flywheel from steel, tungsten can be used with only one third the size of a steel component. Tungsten has very poor machinability (it is one of the hardest pure metals), but a number of tungsten manufacturers offer tungsten alloyed with copper to improve machinability. These alloys have been used to solve many machine dynamics problems.

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.

heal [hi:l] v лікувати, загоюватися

rash [ræ∫] n висип

scratch [skræt∫] n подряпина

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

3. True or false statements.

1. Magnesium is the third most commonly used structural metal.

2. Magnesium was found in 1718.

3. The water with magnesium heals scratches and rashes.

4. Magnesium in its purest form can not be compared with aluminum.

5. Magnesium has low weight, good mechanical and electrical properties.

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

1. Where does the term magnesium originate from?

2. Where is it found?

3. Why did the cows refuse to drink water from a well?

4. Why is magnesium widely used for manufacturing of mobile phones, laptop computers, cameras and other electronic components?

5. Magnesium is used in automotive and truck components, isn’t it?

V. Communicative skills.

• Analyze the table below.

Some of the effects, good and bad, of some alloying elements in aluminum

Alloying element	Effects
Iron	Naturally occurs as an impurity in aluminum ores; small percentages increase the strength and hardness of some alloys and reduce hot-cracking tendencies in castings.
Manganese	Used in combination with iron to improve castability; alters the nature of the intermetallic compounds and reduces shrinkage; the effect on mechanical properties is improved ductility and impact strength.
Silicon	Increases fluidity in casting and welding alloys and reduces solidification and hot-cracking tendencies; additions in excess of 13% make the alloy extremely difficult to machine; improves corrosion resistance.
Copper	Increases strength up to about 12%, higher concentrations cause brittleness; improves elevated temperature properties and machinability.
Magnesium	Improves strength by solid solution strengthening, and alloys with over about 6% will precipitation harden.
Zinc	Lowers castability; high-zinc alloys are prone to hot cracking and high shrinkage; percentages over 10% produce tendencies for stress corrosion cracking; in combination with other elements, zinc promotes very high strength; low concentrations in binary alloys (less than 3%) produce no useful effects.

A number of other elements are added for special purposes, but the above are the most important because of their roles in fabricability and strengthening.

• Answer the following questions.

1. What alloying element in aluminum increases the strength and hardness of alloys and reduces hot-cracking tendencies in castings?

2. What alloying element in aluminum reduces shrinkage and improves ductility and impact strength?

3. What alloying element increases fluidity in casting and welding alloys, reduces solidification and hot-cracking tendencies?

4. What alloying element increases strength up to about 12%, improves elevated temperature properties and machinability?

Topic for discussion: Some of the effects, good and bad, of some alloying elements in aluminum

Unit 7

Topic: Lathes. Machining of Metals

1. Pre-reading tasks.

a) You will read a text about lathes.

• What are lathes used for?

• What kinds of lathes do you know?

b) Read and remember the words in their specialized meanings.

bench lathe [leið] n настільний токарний верстат

boring mill n розточувальний верстат

chucking lathe n патронний токарний верстат

crankshaft [’kræŋk∫a:ft] lathe n карусельний токарний верстат

credit n значення

engine lathe n універсальний токарний верстат

gear [gie] n шестерня

lapping machine n полірувальний верстат

lathe n токарний верстат

lead-screw [skru:] n шляпка гвинта

machine tool n механічний інструмент; ріжучий інструмент

onward [’Ɔnwəd] adj спрямований (що рухається) уперед

pitch n відстань гвинта

planing-machine n стругальний верстат

slide-rest n супорт ковзання

thread n гвинтова різьба

turret [’tʌrit] lathe n револьверний верстат