Childrens Illustrated Encyclopedia

287

Huge structures like

oil tankers and bridges and

tiny objects like nuts and

bolts are all made from steel.

the world produces more

than 1.5 billion tons of steel

every year; it is the most widely

used of all metals. steel is made

from iron, one of the most common

metals in earth’s crust, and carbon,

which comes from coal. Iron has many

uses, including making car engine parts

and magnets. Our bodies also need iron

to work properly. A healthy diet

must include foods such as

green vegetables, which contain

iron. Pieces of iron fall to earth

in meteorites from space. Most

iron, however, comes from iron

ore in rock. Heat ing the ore with

coke (from coal) produces iron.

the Hittites of turkey perfected

iron smelt ing about 1500 bce.

this was the beginning of the

Iron Age, during which iron

gained wide spread use for

making weapons and tools.

MAkIng

Iron and steel

Making metals

by heating their

ores is called

smelting. Huge

factories smelt iron ore

by heating it with coke

to produce iron,

which is rich

in carbon.

removing most

of the carbon

produces steel.

steels of different

quality are made by

adding metals,

such as nickel.

uses Of steel

different kinds

of steel are made

by varying the amount of carbon and other metals

in it. low-carbon steel goes into car bodies; stronger

medium-carbon steel is used for making ships and

steel beams that support structures. High-carbon steel

is very strong but difficult to shape, and is used for

springs and rails that get much wear. steel containing

tungsten metal resists heat and is used in jet engines.

sHAPIng steel

Passing a hot slab

between rollers

presses the soft steel

into plates or sheets.

A forge presses the

steel into more

complex shapes.

casting uses a mold,

in which molten

steel cools and sets

into shape.

rAw MAterIAls

Ironmaking starts with iron ore, coke (a form

of carbon from coal), and limestone. they are

mixed and treated to make lumps called sinter.

BlAst furnAce

the ingredients enter the top of the blast

furnace and move down inside. A blast of

very hot air flows up the furnace. the heat

produces molten iron

from the ore and coke.

limestone removes

impurities, which form

a layer called slag.

stAInless steel

Adding the metals

chromium and nickel

produces stainless

steel, which does

not rust. cutlery

and cookware are often

made of stainless steel. this

metal is also used to make

equipment that must be kept

very clean in places such

as hospitals and dairies.

Rolling

Forging

steel cOnverter

Molten iron from the

blast furnace is poured into

a steel converter where hot

air or oxygen is blown over

it. the heat burns up most

of the carbon from the

iron, leaving molten steel.

steel from old cars and

other waste can be recycled

by adding it to the

converter.

Iron and steel

rust

Iron and steel

objects get rusty

when they are left

outside in damp

conditions. Moist air causes

rust. It changes iron into

iron oxide, a reddish-brown compound

of iron and oxygen. rusting weakens the

metal so that it crumbles away.

Casting uses

molten steel

from the

converter.

Oxygen is blown

through a pipe

on to the surface

of pig iron.

Molten steel

from converter

Continuous

casting

Find out more

coal

Industrial revolution

Iron age

Metals

Iron and steel were

once used to make

weapons and armor,

such as this

16th-century helmet.

Limestone

Iron

ore Coke

Blast

furnace

Slag floats

above the

molten iron.

Molten iron is drained

from the furnace into

large ladles.

Sinter

After blowing with

oxygen, the converter

tilts to discharge

molten steel.

The molten steel

may be cast into

large blocks

called ingots.

cOntInuOus

cAstIng

Molten steel from the

converter sets as it cools

and is held in shape by

rollers. the long slab is then

cut up into lengths and

rolled into steel products.

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