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КАТЕГОРИИ:






Answer the following questions




 

1) What types of molding sand is this text about?

2) What sands must be fine (coarse)?

3) Is bond used for light, medium and heavy sands?

4) What material is used as a band?

5) When is heavy sand used?

 

Find a suitable title for Text Е.

 

Read Text F, translate it and answer the following questions.

 

1) What are the two large groups of casting metals?

2) What alloys do ferrous alloys include?

3) What cast metal is the most important among the ferrous metals?

4) From what material is it made?

5) Is cast iron very strong? Why?

6) Is the melting point of cast iron low or high?

7) Is it economical to produce large machine parts from cast iron?

8) What alloys do the non-ferrous cast metals include?

 

Text F

CASTING METALS

There are two large groups of casting metals: the ferrous metals and non-ferrous metals. Foundries mix the relatively pure metals to produce necessary alloys. The ferrous or iron alloys include all the cast irons, carbon steels and alloy steels.

Among the ferrous metals cast iron is the most important cast material used in the manufacture of products necessary in everyday life. It is made from pig iron by remelting it in the cupola. When the pig iron has been remelted in the cupola, its carbon content is reduced. It contains already from 2 to 5 percent carbon. The more carbon the iron contains, the more brittle it is. That is why the brittleness of cast iron is very high.

So, cast iron is not a very strong material, it is not plastic. But it has a low melting point and is the cheapest, the most economical. It is often used for making objects and machine parts which are to be large but the strength of which is not very important.

The non-ferrous metals used in the foundry are usually alloys of two or more metals. They are copper-base, aluminium-base, zinc-base alloys and some others. All these metals have a lower melting temperature then iron alloys.

 

to include – включать, содержать в себе

alloy steel – легированная сталь

pig iron – доменный чугун, сырцовый (чушковый) чугун

to reduce - восстанавливать

percent - процент

brittle - хрупкий

base – основа

 




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