METALS AS ENGINEERING MATERIALS
People began to use metals after wood and stone, but now metals are more important for our industry than these two old materials.
Metals have such great importance because of their useful properties. Metals are much stronger and harder and that is why some engineering constructions and machines were impossible when people did not know how to produce and how to use metals. Metal is not so brittle as stone which was the first engineering material for people. Strength, hardness and plasticity of metals are the properties which made metals so useful for industry.
It is possible to find some very plastic wood, but it will be much softer than any metal; stone may be very hard, but it is not plastic at all. Only metals have a combination of these three most useful engineering properties.
But it is much more difficult to get the metals from the earth in which they are found than to find some stone or wood. That is why people began to usе metals as engineering materials after stone and wood. The first metal which was produced by people was copper; iron was produced much later.
It is known that metals are very important in our life. Metals have the greatest importance for industry. All machines and other engineering constructions have metal parts. Some of them consist only of metal parts.
About two thirds of all elements found in the earth are metals, but not all metals may be used in industry. Those metals which are used in industry are called engineering metals. The most important engineering metal is iron (Fe) which, in the forms of alloys with carbon (C) and other elements, finds greater use than any other metal.
It should be noted that engineering metals are usually used in modern industry in the form of alloys because the properties of alloys are much better than the properties of pure metals. Only aluminium may be largely used in the form of a simple metal.
So we see that metals form the most important and largest group of engineering materials because they have desirable mechanical and physical properties, can be easily worked into various shapes.
5. What sentences have a predicative in Passive Voice? Compare the translation of sentences with and without Passive Voice.
1) Metals are very important in our life.
2) About two thirds of elements found in the earth are metals.
3) Most elements are found in the earth.
4) Metals consisting of iron and some other elements are called ferrous metals.
5) The most important non-ferrous metals are copper, aluminium, lead and others.
6) They are used much less than ferrous metals.
7) Ferrous metals are much cheaper than non-ferrous metals.
8) Different metals are produced in different ways.
6. What sentences have Participle as an attribute? Translate them.
1) Alloys consist of a simple metal combined with some other elements.
2) People combined a simple metal with some other elements to get an alloy.
3) Only aluminium may be used in the form of a simple metal.
4) Of all 100 % metals produced by the world's metallurgical industry during one year the production of ferrous metals is about 94 % (per cent).
5) Metals called ferrous contain iron.
6) People used metals after wood and stone.
7) The plant produced engineering metals for industry.
Read Text E again. Answer the questions without looking into the text.
1) When did people begin to use metals?
2) Why are metals the most important engineering materials?
3) What three most useful engineering properties do metals combine?
4) What was the first metal produced by people?
5) How will you call metals which are used in industry?
6) What is the most important engineering metal?
7) In what form are engineering metals most often used in industry?
8) What metal is largely used in the form of a simple metal?
Independent tasks