Metals are materials most widely used in industry because of their properties. The study of the production and properties of metals is known as metallurgy

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 is why metals are malleable (can be deformed and bent without fracture) and ductile (can be drawn into wire). 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 than1 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 drawing, rolling, hammering and extrusion, but some require hot-working. Metals are subject to metal fatigue and to creep (the slow increase in length under stress) causing deformation and failure. Both effects are taken into account by engineers when designing, for example, airplanes, gas-turbines, and pressure vessels for high-temperature chemical processes. Metals can be worked using machine-tools such as lathe, milling machine, shaper and grinder.

The ways of working a metal depend on its properties. Many metals can be melted and cast in moulds, but special conditions are required for metals that react with air.

Вариант №2.

I. Перепишите предложения, определите степени сравнения прилагательных или наречий, переведите на русский язык.

1. The climate in India is hotter than in our country.

2. France is larger than England.

3. Moscow has the largest population in our country.

4. Autumn is the wettest season in the year.

5. It was the coldest day in winter.

II. Перепишите предложения, определите видовременные формы глаголов и укажите их инфинитив, переведите предложения на русский язык.

1. The weather changed yesterday.

2. The farmers will harvest crops in time.

3. Farm machinery has changed life and work on our farm.

4. Now I am reading a very interesting book about London.

5. Today it is not so cold as it was yesterday.

III. Перепишите предложения, подчеркните в каждом из них модальный глагол или его эквивалент, переведите предложения на русский язык.

1. They were able to do this work.

2. I am to see him tomorrow.

3. You must come tomorrow.

4. I had to read this book.

5. I can help you.

IV. Перепишите предложения. Подчеркните причастия, установите функции каждого из них (определение, обстоятельство, часть сказуемого). Переведите предложения на русский язык.

1. I am going to the library.

2. Building this house they used new materials.

3. He sat at the table playing chess.

4. The opened book is on the table.

5. The method used is important for the experiment

V. Прочитайте и устно переведите весь текст. Письменно переведите абзац 1.

Steel

The most important metal in industry is iron and its alloy - steel. Steel is an alloy of iron and carbon. It is strong and stiff, but corrodes easily through rusting, although stainless and other special steels resist corrosion. The amount of carbon in a steel influences its properties considerably. Steels of low carbon content (mild steels) are quite ductile and are used in the manufacture of sheet iron, wire, and pipes. Medium-carbon steels containing from 0.2 to 0.4 per cent carbon are tougher and stronger and are used as structural steels. Both mild and medium-carbon steels are suitable for forging and welding. High-carbon steels contain from 0.4 to 1.5 per cent carbon, are hard and brittle and are used in cutting tools, surgical instruments, razor blades and springs. Tool steel, also called silver steel, contains about 1 per cent carbon and is strengthened and toughened by quenching and tempering.

The inclusion of other elements affects the properties of the steel. Manganese gives extra strength and toughness. Steel containing 4 per cent silicon is used for transformer cores or electromagnets because it has large grains acting like small magnets. The addition of chromium gives extra strength and corrosion resistance, so we can get rust-proof steels. Heating in the presence of carbon or nitrogen-rich materials is used to form a hard surface on steel (case-hardening). High-speed steels, which are extremely important in machine-tools, contain chromium and tungsten plus smaller amounts of vanadium, molybdenum and other metals.

Вариант №3.

1. In spring the days are longer and warmer than in winter.

2. The Ob is one of the longest Siberian rivers.

3. This is the highest building in our town.

4. This collective farm is the richest in our region.

5. Baikal is the largest fresh-water lake in Europe and Asia.

1. We went to this farm last year.

2. He has made three experiments today.

3. I have seen this film.

4. We will begin our work next week.

5. They had finished their lessons by 7.

1. You must come tomorrow.