4.4. Connect the two matching parts of the sentences related to the blast furnace operation.

1. Hot air is blasted	a) iron ores.
2. Iron ore is mixed	b) to the furnace bottom.
3. Flux is needed	c) of three components in the proper proportions.
4. The molten iron and slag flow	d) abundant element on earth.
5. Oxygen is the most	e) nozzles through which air is forced into the blast furnace.
6. Tuyeres are	f) to absorb the impurities.
7. Charge consists	g) through the furnace.
8. Hematite and magnetite are	h) with coke and flux.

4.5. Read the headline of the following text and predict what kind of facts/information you could find in it. Then read the text and say what you guessed correctly and what you didn’t.

Vocabulary

iron-carbon alloy	—	железоуглеродистый сплав
wrought iron	—	ковкий чугун, кованое железо
machine v	—	обрабатывать механически
adjust v	—	регулировать, выверять, корректировать
content n	—	содержание
alloying element	—	легирующий элемент
texture n	—	текстура, структура
harmful a	—	вредный, опасный
effect n	—	влияние, воздействие, эффект
carbon steel	—	углеродистая сталь
low-alloy steel	—	низколегированная сталь
high-alloy steel	—	высоколегированная сталь
account for phr v	—	составлять
sheet iron	—	тонколистовой прокат
medium-carbon steel	—	среднеуглеродистая сталь
forging n	—	ковка
welding n	—	сварка
cutting n	—	резка
cutting tool	—	режущий инструмент, резец
spring n	—	пружина

Ferrous metals

Iron is the main component of iron-carbon alloys such as cast iron, wrought iron and steels. Because of their wide range of properties, iron-carbon alloys are widely used in engineering and are the most important of all the industrial metals.

Cast iron is one of the oldest ferrous alloys known to man. It is a general term applied to iron-carbon alloys containing more than 2% carbon. It is the cheapest of the ferrous metals and must be cast into shape as it does not possess the necessary plasticity when worked in the solid state. There are many variations in the structure and physical properties of cast iron that may be classified into three groups: grey cast iron, white cast iron and malleable cast iron.

Wrought iron is more or less pure iron hardened slightly by heat treatment and hammering. It is quite ductile and has high resistance to corrosion. The carbon content of wrought iron is generally less than 0.1%. Now wrought iron is used mostly for ornamental gates.

Steel is an iron-carbon alloy containing 0.003–2% carbon. Adjusting the carbon content is the simplest way to change the properties of steel since the many variations of steel’s basic microstructures depend on that content. Each particular microstructure has its specific degrees of hardness, strength, toughness, corrosion resistance and electrical resistivity.

The properties of a steel may be further modified by adding other alloying elements. Manganese comes directly after carbon in importance as a constituent of all types of steel. It deoxidizes the molten steel giving it the desired texture and is able to minimize the harmful effect of sulphur. Sulphur and phosphorus are the most harmful impurities of steel whose amounts should be limited. Based on the quantity of alloying elements, steels can be grouped into three major classes: carbon steels, low-alloy steels and high-alloy steels.

Carbon steels are the most widely used and account for 90% of the world’s steel production. Low-carbon steels are quite ductile, and are used in making sheet iron, wire and pipes. Medium-carbon steels being tougher and stronger, engineers design them as structural materials. Both low-carbon and medium-carbon steels are suitable for forging and welding. High-carbon steels are hard and brittle, and are used in cutting tools, surgical instruments, razor blades and springs.

4.6. Study Table 1 and answer the following questions.

Table 1

Carbon Content-Malleability and Carbon Content-Elasticity Relations for Ferrous Metals

FERROUS METAL	MALLEABILITY	ELASTICITY	CARBON CONTENT
Wrought iron	good	good	0.05%
Low-carbon steels	quite good	quite good	0.08–0.25%
Medium-carbon steels	not very good	not very good	0.25–0.65%
High-carbon steels	poor	poor	0.65–2%
Cast iron	very poor	very poor	2–5%

1. Which properties depend on the carbon content?

2. Which metal has the most carbon in it?

3. Which metal contains the least carbon?

4. Which metal is the least malleable?

5. Which metal has the most elasticity?

6. Which steels contain approximately 0.65–2% carbon?

7. Which steels are more malleable, medium or high-carbon steels?

8. Which steels have less elasticity, high or low-carbon steels?

4.7. Study the model below and make sentences relying on Table 1.

Model:

wrought iron/malleable →

Wrought iron contains about 0.05% carbon. Therefore, it is very malleable.

1. low-carbon steels/malleable

2. medium-carbon steels/elastic

3. high-carbon steels/malleable

4. cast iron/elastic

4.8. a) Read the text and fill in the correct words derived from the words in brackets. There is an example at the beginning (0). b) Reread the text and say what caused progress in steelmaking in the 19^th century.