7. Casting metals

Cast Iron.The term cast iron is applied to ferrous alloys. Among the ferrous metals, cast iron occupies first place and is recognized as one of the cheapest materials used in the manufacture of everyday life products. Cast iron is not con­sidered a very strong or tough structural material, but it is the most economical. Its low melting point, low shrinkage, good fluidity, and machinability are properties that recommend its use.

Pig Iron.The chief raw material for cast iron is pig iron, which is produced in a blast furnace by smelting iron ore with coke and a flux (substances promoting fusion) such as limestone. The final analysis of the pig iron is substantially determined by the kind of iron ore used in the smelting pro­cess.

Pig iron got its name from the shape of the molds in which metal from the blast furnace was cast. Originally, the pigs were cast in sand molds.Modern large-volume production of pig iron is carried out by casting blast-furnace metal by means of a large machine, which is in principle an endless conveyer chain of pig molds.Some pig irons are used in gray-iron foundries, and are called foundry pig irons. Pig iron used for making steel by the acid Bessemer process or the acid open-hearth process is known as Bessemer pig iron. Basic pig iron is used for the basic open-hearth process.

Non-Ferrous Metals.The non-ferrous metals used in the foundry are usually alloys of two or more metals. Non-fer­rous castings include those composed of copper-base alloys (brass and bronze), aluminium-base alloys, zinc-base alloys, tin-base alloys, lead-base alloys, bearing metals, and some special alloys composed of magnesium or nickel and other metals.

1) Mark these statements T or F according to the information in the text.

1. Among the ferrous metals, pig iron occupies first place and is recognized as one of the cheapest materials used in the manufacture of everyday life products.

2. The chief raw material for cast iron is pig iron.

3. Pig iron is not con­sidered a very strong or tough structural material, but it is the most economical.

4. The non-ferrous metals used in the foundry are usually alloys of two or more metals.

5. Pig iron used for making steel by the acid Bessemer process or the acid open-hearth process is known as Bessemer pig iron.

2) Match heads and tails

Pig iron got its name from the shape of the molds	the kind of iron ore used in the smelting pro­cess.
Among the ferrous metals, cast iron occupies first place and is recognized	in which metal from the blast furnace was cast.
The final analysis of the pig iron is substantially determined by	are usually alloys of two or more metals
The non-ferrous metals used in the foundry	and are called foundry pig irons
Some pig irons are used in gray-iron foundries,	as one of the cheapest materials used in the manufacture of everyday life products.

3) Match these terms with their definitions

1 fluidity	A. crude iron produced in a blast furnace and poured into moulds in preparation for making wrought iron, steels, alloys, etc
2 pig iron	B.a hard sedimentary rock, composed mainly of calcium carbonate or dolomite, used as building material and in the making of cement
3 cast iron	C.English engineer and inventor. By 1860 he had developed the Bessemer process, the first successful method of making steel in quantity at low cost
4 limestone	D.a hard, relatively brittle alloy of iron and carbon that can be readily cast in a mold and contains a higher proportion of carbon than steel (typically 2.0 - 4.3 percent)
5 Bessemer	E.the state of being fluid

4) Fill in the gaps

The term____1___ is applied to ferrous alloys. The chief ____2____for cast iron is pig iron, which is produced in_____3____ by smelting iron ore with coke and a flux (substances promoting fusion) such as____4____.got its name from the shape of the molds in which metal from the blast furnace was cast.

1. raw material

2. pig iron

3. cast iron

4. limestone

5. a blast furnace